Speaker 1: Section fourteen of the Science History of the Universe, Volume four.
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Speaker 1: Anne Crosby the Science History of the Universe, Volume four,
Speaker 1: edited by Francis Rolt Wheeler. Chemistry, Chapter ten, The Atomic
Speaker 1: Theory and the work of Davy. A desire injinite in
Speaker 1: the human mind to find an explanation of natural phenomena
Speaker 1: by the aid of speculations respecting the ultimate constituents of
Speaker 1: matter resulted in guesses and ideas concerning Adams in olden times, without, however,
Speaker 1: the evolution of an exact chemical atomic theory. With respect
Speaker 1: to the hypothesis of the ancient philosophers regarding the constitution
Speaker 1: of matter, the following estimate by Clifford will suffice in
Speaker 1: this connection. From the earliest times that man began to
Speaker 1: form any coherent idea in the world at all, they
Speaker 1: began to guess, in some way or other, how it
Speaker 1: was that it all began, and how it was all
Speaker 1: going to end. Modern speculations are attempts to find out
Speaker 1: how things began and how they are to end, by
Speaker 1: consideration of the way in which they are going on. Now,
Speaker 1: a great number of people appeared to have been led
Speaker 1: to the conclusion that the modern theory of the molecular
Speaker 1: constitution of matter was very similar to the guesses which
Speaker 1: we find in ancient writings Democratus and Lucratus. It so
Speaker 1: happens that these ancient writers did hold a view of
Speaker 1: the constitution of things which in many striking respects agrees
Speaker 1: with the view which we hold in modern times. The
Speaker 1: difference between the ancient and modern views is mainly this.
Speaker 1: The atomic theory of Democratus was a guess, and no
Speaker 1: more than a guess. Everybody around him was guessing about
Speaker 1: the origin of things, and they guess in a great
Speaker 1: number of ways to make a guess which was more
Speaker 1: near the right thing than any of the others end.
Speaker 1: The conception of Adams had up to the close of
Speaker 1: the eighteenth century been almost entirely the property of the
Speaker 1: metaphysician and the mathematical physicist, and had assisted in extending
Speaker 1: their sciences. With the exception of Serenate and Boyle, chemists
Speaker 1: had aided little in its formation, and less in its establishment,
Speaker 1: nor had they derived inspiration from it for the proper
Speaker 1: founding of their own science. For more than a century
Speaker 1: they had been following the igneous fatuus of a false
Speaker 1: theory of combustion and a most elusive hypothetical Phlogiston. The
Speaker 1: close of the eighteenth century found them engaged in a
Speaker 1: bitter strife over these theories, and who fully occupied to
Speaker 1: think of much else than the destruction of the old
Speaker 1: beliefs and the adaptation of the new. The mastermind of Levoisier,
Speaker 1: who had brought this revolution, was busied with the greater
Speaker 1: work of reconstruction, and dealing a little with the hypothesis,
Speaker 1: which could not be directly proved by experiments in his laboratory,
Speaker 1: was laying broad and strong foundations of the new chemistry. Consequently,
Speaker 1: the works of Bergmann, Shiel, Priestley, Black, Cavendish, Macker, and
Speaker 1: others did not treat of atoms in their moving forces,
Speaker 1: except in an occasional indefinite reference to some sort of particle.
Speaker 1: Yet the chemists were the very one required to undertake
Speaker 1: the scientific development of the atomic hypothesis and to establish
Speaker 1: it as a theory, by discovering a series of facts
Speaker 1: which were connected together by it, and found in it
Speaker 1: a simple explanation. In seventeen eighty three, the English chemist
Speaker 1: Kurwan went so far as to refer to affinity as
Speaker 1: the force which holds atoms so intimately together that simple
Speaker 1: mechanical means are insufficient to separate them, while as Countryman Higgins,
Speaker 1: writing in seventeen ninety on the composition of sulfurous in
Speaker 1: sulfuric acid, expresses the opinion that the atom of sulfur
Speaker 1: is with one atom of oxygen in the first but
Speaker 1: with two atoms in the second. It is in the
Speaker 1: view of this statement and others similar to it, that
Speaker 1: some have regarded Higgins as the real originator of the
Speaker 1: modern atomic doctrine. However, Higgins restricted his attention to a
Speaker 1: small number of compounds. His conceptions were not consistent with
Speaker 1: the fact he regarded those weights of elements which combine
Speaker 1: to form the simplest compounds as in general equal, and
Speaker 1: he made no attempt to seek confirmation for any theory
Speaker 1: he had in the laboratory. For long, the common consent
Speaker 1: of the public opinion was given the undivided honor due
Speaker 1: to the discoverer of the great atomic generalization in its
Speaker 1: modern aspect to John Dalton. Before the establishment of the
Speaker 1: chemical atomic theory could be brought to completion, however, it
Speaker 1: became necessary to fix the significance of the term chemical proportions,
Speaker 1: according to which simple substances unite to form compound bodies,
Speaker 1: and an important part of this question was solved by
Speaker 1: two chemists prior to Dalton, Richter and Proust. Jeremiah Benjamin
Speaker 1: Richter seventeen sixty two eighteen oh seven, published in his
Speaker 1: de Yusu mattheos in Shumia seventeen eighty nine, Alfans Grunde
Speaker 1: der stokem itri Uda meskunst Schimisha Stelemanta seventeen forty two
Speaker 1: seventeen ninety four and uberdainyrin gegenstande Dayershumi seventeen ninety one
Speaker 1: eighteen oh two. The results of researches made mainly Well
Speaker 1: employed as a works chemist in Berlin. The last two
Speaker 1: mentioned trustees contained the conclusion which he drew from his
Speaker 1: work upon the proportions by weight in various compounds. Richter
Speaker 1: looked upon chemistry as a branch of applied mathematics and
Speaker 1: exhibited all the distressing qualities of a person possessed by
Speaker 1: a fixed idea. He spent his life in seeking a
Speaker 1: rethmetical regularities and the weights of acids and alkalis, neutralizing
Speaker 1: each other, and finding them in spite of their non existence. Nevertheless,
Speaker 1: he managed to make discoveries of the highest importance. He
Speaker 1: not only noticed but also correctly interpreted the fact that
Speaker 1: when two neutral salts decompose one another, the resulting salts
Speaker 1: are neutral. To quote his conclusions concerning that very common
Speaker 1: experience that two neutral salts on decomposition again produce neutral compounds,
Speaker 1: I could draw no direct inference other than that fixed
Speaker 1: quantitative relations must exist between the constituents of the neutral salts.
Speaker 1: If a solution of two compounds is so constituted that
Speaker 1: neither of them, as long as it remains in the solution,
Speaker 1: exhibits the peculiar characteristics it had before solution example, given
Speaker 1: the reactions of an acid or of an alkali, then
Speaker 1: such a solution is called saturated or neutral, or also
Speaker 1: a neutral compound. When two neutral solutions are mixed and
Speaker 1: a decomposition ensues, the newly formed products are also, almost
Speaker 1: without exception neutral. Hence, it follows that if the combining
Speaker 1: ratios in the original compounds be known. Those in the
Speaker 1: newly formed compounds are also known end cf. Wenzel, seventeen
Speaker 1: forty seventeen ninety three. At an earlier date, seventeen seventy
Speaker 1: seven had demonstrated that acids and bases combine in constant proportions,
Speaker 1: but it failed to note the persistency of the neutrality
Speaker 1: in the double decomposition of the neutral salts. Richter deduced
Speaker 1: from the maintenance of neutrality when one metal precipitates another
Speaker 1: from a neutral solution, a relation Bergmann had observed, by
Speaker 1: which he interpreted in terms of another theory, that the
Speaker 1: quantities of two metals which dissolve in the same amount
Speaker 1: of acid also unite in their oxides with the same
Speaker 1: amount of oxen. Therefore, he established that quantities of two
Speaker 1: substances which were equivalent in one reaction are also equivalent
Speaker 1: in the others. He was the originator of stoiccheometry, or
Speaker 1: the art of chemical measurement, which had to deal with
Speaker 1: the laws according to which substances unite to form chemical compounds.
Speaker 1: Nonwithstanding the fact that Richter's trustees contained such important discoveries,
Speaker 1: these remained unrecognized until Fischer published a table of the
Speaker 1: relative affinities of bases and acids, founded on the values
Speaker 1: Richter had obtained in his translation of Bertola's Richersch made
Speaker 1: in eighteen o two. Bertoll accepted the law of proportionality
Speaker 1: and gave an account of it in his Assay de
Speaker 1: Statique Chemik, in which he reprinted Fisher's note. Thus, Richter's work,
Speaker 1: which at the time of its publication had been almost
Speaker 1: completely ignored, became more widely known and appreciated. Louis Jose
Speaker 1: Prauss seventeen fifty five eighteen twenty six, although a Frenchman
Speaker 1: by birth, conducted his most important researches in Madrid, where
Speaker 1: he settled after seventeen ninety one. The work for which
Speaker 1: he has celebrated was the result of a series of
Speaker 1: questions which Bertolai had advanced. The two works of Bertolas
Speaker 1: on affinity Richerche surlet luis de la finiti and Essay
Speaker 1: don Statique Chemique were particularly directed against false views of
Speaker 1: affinity and a misuse of the so called affinity tables
Speaker 1: of Geoffrey Bergman and others. He contended that affinity was
Speaker 1: by no means a simple force, an easy to determine
Speaker 1: or measure, but was influenced by temperature, physical state cohesion,
Speaker 1: and especially by mass, the latter largely determined the course
Speaker 1: of chemical reactions. He went further, however, and from the
Speaker 1: correct premises of the influence of mass on the chemical
Speaker 1: effort produced, Bertolas drew the erroneous inference that mass had
Speaker 1: an influence not only on the amount of change, but
Speaker 1: also on the kind, producing a continuous variation in the
Speaker 1: ratio in which the constituents are united in a compound.
Speaker 1: He asserted the variability of the composition of chemical compounds,
Speaker 1: the possibility of combination between constituents, and all sorts of
Speaker 1: continuously varying ratios. None of the other leading chemists of
Speaker 1: the day were able to concur with his views as
Speaker 1: to the lack of any fixity or constancy of proportion
Speaker 1: in chemical compounds. Yet they raised no objection, probably owing
Speaker 1: to Bertolai's reputation, and it remained for Pross to attack
Speaker 1: the theoretical conclusions of his eminent contemporary, Praus. Numerous papers
Speaker 1: in his controversy with Bertolai appeared in the journal Deficique
Speaker 1: between the years eighteen oh two and eighteen oh eight.
Speaker 1: The lucidity of the arguments employed, the variety of the
Speaker 1: experimental work described, and the freedom and keenness of the
Speaker 1: style entered. These papers, which deal exclusively with the distinctly
Speaker 1: dry subject of quantitative analysis most interesting reading even now.
Speaker 1: Prousse proves that substances formed under the most varied conditions
Speaker 1: have a fixed composition, and he shows that Bertille's examples
Speaker 1: of variable composition were all cases of mixtures. This involves
Speaker 1: him in the necessity of discriminating between mixtures and compounds,
Speaker 1: and undertaking the difficulties of which he fully realized and
Speaker 1: with which he dealt in a manner very much like
Speaker 1: that still resorted to for the same purpose von Meyer.
Speaker 1: In seventeen ninety nine. Prouss had proved the constant composition
Speaker 1: of native and artificial carbonate of copper, and had enunciated
Speaker 1: the general principle of which this constituted. An example of
Speaker 1: greater importance than these, where observations he made upon the
Speaker 1: two compounds iron forms with sulfur and the two stages
Speaker 1: of oxidation shown by tin. He father investigated the compounds
Speaker 1: of many cobalt, nickel, and copper, and throughout he found
Speaker 1: that vary the conditions and relative masses at pleasure. The
Speaker 1: oxides and sulfides produced always have a definite composition. To
Speaker 1: be sure, an element might combine with oxygen or sulfur
Speaker 1: in two proportions, but each has a compound of definite proportions.
Speaker 1: Prowse showed the air which underlay the old method of
Speaker 1: determining the quantity of oxygen and oxides, of estimating the
Speaker 1: metal and calculating the oxygen by difference, proving that in
Speaker 1: many cases the bodies so examined were not oxides at all,
Speaker 1: but compounds containing hydrogen hydrooxides we now call them. He
Speaker 1: moreover demonstrated that many of the bodies on analysis of
Speaker 1: which Bertolt had based his generalizations were not simple at all,
Speaker 1: but mixtures of substances themselves of perfectly definite composition. So
Speaker 1: accurate were his analytical investigations and zoological his reasoning that
Speaker 1: Bertolu was overcome at every point. The law of definite
Speaker 1: chemical proportions as we now have it, was the fruit
Speaker 1: of his preserving labors. This law is one of the
Speaker 1: fundamental principles of chemistry. It is expressed by the greatest
Speaker 1: teacher of chemistry as follows quote. If one substance is
Speaker 1: transformed into another, then the masses of these two substances
Speaker 1: always bear a fixed ratio to each other. If several
Speaker 1: substances react together, then their masses, as well as those
Speaker 1: of the new bodies formed, always bear fixed proportions to
Speaker 1: each other. End quote Oswald Outlines of General Chemistry and dubtedly.
Speaker 1: If Prousts had calculated the results of experiments on the
Speaker 1: composition of binary compounds sulfide's oxides in another manner from
Speaker 1: what he did, he would have discovered the law of
Speaker 1: multiple proportions. But the propounding of this is due to Dalton.
Speaker 1: John Dalton seventeen sixty six eighteen forty four was born
Speaker 1: at Eaglesfield in Cumberland, the son of a poor weaver.
Speaker 1: Endowed with natural aptitude in an ende domitable will, he
Speaker 1: used all possible opportunities for the study of mathematics and
Speaker 1: natural philosophy. From seventeen eighty one to seventeen ninety three
Speaker 1: he taught school, instructed and lectured at Kendall, devoted all
Speaker 1: the time and energy he could spare to scientific investigations,
Speaker 1: chiefly meteorological. In seventeen ninety three he went to Manchester
Speaker 1: as tutor of mathematics and natural philosophy at a Presbyterian college.
Speaker 1: Though he resigned his post six years later, he remained
Speaker 1: in Manchester to the end of his life, earning his
Speaker 1: living as a private teacher and devoting himself uninterruptedly and
Speaker 1: earnestly to scientific research. The earliest researches of Dalton on
Speaker 1: the expansion of gases by heat and their absorption by
Speaker 1: liquids were of considerable influence on his later chemical work,
Speaker 1: as it was through them that he acquired the experimental
Speaker 1: skill which led to the discovery of the law of
Speaker 1: multiple proportions, which with the conception of the atomic theory
Speaker 1: which arose from it from eighteen oh two. On November twelfth,
Speaker 1: eighteen oh two, Dalton read a paper entitled an Experimental
Speaker 1: Inquiry into the properties of the several gases or elastic
Speaker 1: fluids constituting the atmosphere, on which he found the first
Speaker 1: example of the law in determining the amount of oxygen
Speaker 1: in the air. The following experiment was performed quote, if
Speaker 1: one hundred measures of common air be put to thirty
Speaker 1: six pure nitrous gas and a tube three sixteenth of
Speaker 1: an inch wide and five inches long. After a few minutes,
Speaker 1: the whole will be reduced to seventy nine or eighty
Speaker 1: measures and exhibit no signs of either oxygeness or nitrous gas.
Speaker 1: If one hundred measures of common air be admitted to
Speaker 1: seventy two of nitrous gas in a wide vessel over water,
Speaker 1: such as to form a thin stratum of air, and
Speaker 1: an intermediate momentary agitation be used, there will, as before
Speaker 1: be found seventy nine or eighty measures of pure asiotic
Speaker 1: gas nitrogen for a residuum. If in the last experiment
Speaker 1: less than seventy two measures of nitrous gas be used,
Speaker 1: there will be a residuum containing oxygenous gas. If more
Speaker 1: than some residuary nitrous gas will be found, These facts
Speaker 1: clowly point out the theory of the process. The elements
Speaker 1: of oxygen may combine with a certain portion of nitrous gas,
Speaker 1: or with twice that portion, but with no intermediate quantity.
Speaker 1: In the former case, nitric acid is the result in
Speaker 1: the latter nitrous acid. But as both these may be
Speaker 1: formed at the same time, one part of the oxygen
Speaker 1: going to one of the nitrous gas and another to two,
Speaker 1: the quantity of nitrous gas absorbed should be variable from
Speaker 1: thirty six to seventy two percent for common air end quote.
Speaker 1: With regard to this experiment, Rosco says, quote and the
Speaker 1: memorable case in which Dalton announces the first instance of
Speaker 1: combination in multiple proportions, the whole conclusion is based upon
Speaker 1: an erroneous experimental basis. If we repeat the experiment as
Speaker 1: described by Dalton, we do not obtain the results he
Speaker 1: arrived at. We see that Dalton's conclusions were correct, although
Speaker 1: in this case it appears to have been a mere
Speaker 1: chance that his experimental results rendered such a conclusion possible
Speaker 1: end quote. The first that the observations of Dalton, which
Speaker 1: furnished the experimental basis for the atomic theory, consisted in
Speaker 1: the determination of the composition of two hydrides of carbon
Speaker 1: Dalton rites quote. It was in the summer of eighteen
Speaker 1: oh four that I collected, at various times and in
Speaker 1: various places, the inflammable gas marsh gas, obtained from Pods
Speaker 1: end quote. He found that marsh gas, like ollefiant gas ethylene,
Speaker 1: contains nothing but carbon and hydrogen, and that these substances,
Speaker 1: termed light and heavy carbureted hydrogen, respectively, showed a simple
Speaker 1: multiple ratio between the weights of the constituent elements, namely
Speaker 1: and carbureted hydrogen from stagnant water. Four point three of
Speaker 1: carbon were combined with two of hydrogen. An oleefant gas
Speaker 1: four point three of carbon were combined with one of hydrogen.
Speaker 1: This regularity induced him to investigate other compounds in the
Speaker 1: same direction. Thus, in the case of carbonic oxide and
Speaker 1: carbonic acid, he found that for the same amount of carbon,
Speaker 1: the ratios of oxygen present, and these were again respectably
Speaker 1: as one to two. His convictions that there must be
Speaker 1: a law underlying these simple relations scarcely nesitated any further
Speaker 1: accretion after he had encountered similar simple numeric proportions, and
Speaker 1: the results of his analysis of nitrous oxide, nitric oxide,
Speaker 1: nitrous acid, and nitric eas aid in essence the anhydrates
Speaker 1: of the last two and the oxygen compounds of sulfur.
Speaker 1: He had therefore demonstrated that when different quantities of one
Speaker 1: element combined chemically with one of the same quantity of another,
Speaker 1: these amounts stood in a simple relation to one another,
Speaker 1: a relation which could be expressed with whole numbers. The
Speaker 1: law of multiple proportions was thus discovered. It had indeed
Speaker 1: been deduced from experiments, which were of necessity not very exact,
Speaker 1: but this was to be expected from the condition of
Speaker 1: analytical chemistry at that time. Dalton next sought an explanation
Speaker 1: of the numerical relations he had discovered, and this was
Speaker 1: afforded him by the atomic hypothesis. For instance, he had
Speaker 1: but to assume that in carbon monoxide one atom of
Speaker 1: carbon was combined with one of oxygen, and in carbonic acid,
Speaker 1: one atom of carbon was united to two of oxygen.
Speaker 1: Upon his base, systoletly erected is atomic theory, which may
Speaker 1: be detailed from statements in his new System of chemical
Speaker 1: philosophy eighteen oh eight eighteen ten. As follows number one,
Speaker 1: all bodies of sensible magnitude are constituted of a vast
Speaker 1: number of extremely small particles or atoms of matter, bound
Speaker 1: together by a force of attraction, which, as it endeavors
Speaker 1: to prevent their separation, is called attraction of cohesion, but
Speaker 1: as it collects them from a dispersed state, is called
Speaker 1: attraction of aggregation, or more simply affinity. Number two. The
Speaker 1: ultimate particles of all homogeneous bodies are perfectly like in
Speaker 1: weight figure et cetera. In other words, every particle of
Speaker 1: water is like every other particle of water. Every particle
Speaker 1: of hydrogen is like every other particle of hydrogen, et cetera.
Speaker 1: Number three, No new creation or destruction of matter is
Speaker 1: within the reach of chemical agency. All ye elements we
Speaker 1: can produce consist in separating particles that are in a
Speaker 1: state of cohesion or combination and joining those that were
Speaker 1: previously at a distance. Number four. The ultimate particles of
Speaker 1: all simple bodies are atoms, incapable of feather division. These atoms,
Speaker 1: at least viewed along with their atmospheres of heat, are
Speaker 1: all spheres, and are possessed of particular weights, which may
Speaker 1: be denoted by numbers number five. If there are two
Speaker 1: bodies which are disposed to combine, then their combination takes
Speaker 1: place by atoms number six. In an elastic gas, each
Speaker 1: particle occupies the center of a comparatively large sphere and
Speaker 1: supports its dignity by keeping all the rest which, by
Speaker 1: their gravity or otherwise are disposed to encroach upon it
Speaker 1: at a respectful distance. The methods by which Dalton determine
Speaker 1: the relative atomic weights from the proportions by weight in
Speaker 1: which the elements unite to form compounds falls next to
Speaker 1: be described. To accomplish this, the first thing necessary was
Speaker 1: to settle the number of atoms in a compound. According
Speaker 1: to Dalton, this number is to be sought for in
Speaker 1: general in the simplest possible ratios. In estimating it, he
Speaker 1: started from the following principles. Number one, When only one
Speaker 1: compound of two elements is known, this is composed of
Speaker 1: an atom of the second order. Number two. When two
Speaker 1: compounds are known, the one consists of an atom of
Speaker 1: the second and the other of an atom of the
Speaker 1: third order. Number three. When three compounds are known, one
Speaker 1: atom of the second and two atoms of the third
Speaker 1: order must be assumed. How did Dalton, I'll proceed to
Speaker 1: the determination of the atomic weights, in essence, the relative
Speaker 1: weights of the smallest particles. In the first place, it
Speaker 1: was necessary to choose a unit for comparisons. Unit He
Speaker 1: assumed hydrogen, but the atomic weight equals one, and he
Speaker 1: referred all the other atomic weights to this. To fix
Speaker 1: the others. He then applied his first principle. At that time,
Speaker 1: only one compound each of oxygen and if nitrogen with
Speaker 1: hydrogen was known, namely water and ammonia, respectively. Therefore, the
Speaker 1: atomic weights of oxygen and nitrogen can be determined directly
Speaker 1: from the composition of these compounds. In this way, Dalton
Speaker 1: found them to be seven and five, respectively. He checked
Speaker 1: the numbers so obtained by the proportions of the oxygen
Speaker 1: and nitrogen. In the oxygen compounds. Of nitrogen, he was
Speaker 1: acquainted with four of the latter. In nitrogoxide, he found
Speaker 1: seven parts of oxygen for five of nitrogen. Its atom
Speaker 1: was therefore the atom of the second order derived from
Speaker 1: these elements. In nitric acid, according to his view, there
Speaker 1: were fourteen parts of oxygen for five of nitrogen, or
Speaker 1: two atoms of the former gas for one of the latter.
Speaker 1: In nitrous oxide, seven parts of oxygen were combined with
Speaker 1: ten parts of nitrogen, and in this he therefore assumed
Speaker 1: two atoms of nitrogen and one of oxygen. Nitrous acid, however,
Speaker 1: is supposed to contain ten and a half parts of
Speaker 1: oxygen for five of nitrogen, and in it he might
Speaker 1: have assumed two atoms of nitrogen and three of oxygen.
Speaker 1: He preferred, however, to regard the substance as a compound
Speaker 1: of nitric acid and nitric oxide. Likewise, he found an
Speaker 1: ethylene five point four parts of carbon for one of hydrogen,
Speaker 1: and in marsh gas the same quantity of carbon for
Speaker 1: two of hydrogen. On this account, he regarded ethylene as
Speaker 1: consisting of atoms of the second order, and assumed the
Speaker 1: atomic weights of carbon to be five point four. Carbonic
Speaker 1: Oxide likewise consisted of atoms of the second order, since
Speaker 1: he found in it seven parts of oxygen for five
Speaker 1: point four of carbon, while carbonic anhydride and atoms of
Speaker 1: the third order because it contains fourteen parts of oxygen
Speaker 1: for five point four of carbon. As the analytical methods
Speaker 1: of Dalton employed reliable to many sources of error, it
Speaker 1: was out of the question that the results he obtained
Speaker 1: could be accurate. However, it was he who propounded the
Speaker 1: principle of the determination of the combining weights of the elements,
Speaker 1: and this work brought him everlasting fame. Dalton's atomic theory,
Speaker 1: generally speaking, was favorably received by chemists. Thomas Thompson seventeen
Speaker 1: seventy three eighteen fifty two, who founded the first chemical
Speaker 1: laboratory for general instructions in Great Britain while professor in
Speaker 1: the University of Glasgow, became its devouted supporter, and his
Speaker 1: system of chemistry eighteen o seven made it known to
Speaker 1: the general public. In eighteen oh eight, Thompson supplied an
Speaker 1: observation of his own in support of the law of
Speaker 1: multiple proportions. Dalton's attempts at a graphic presentation of the
Speaker 1: ultimate particles of various substances must not be forgotten. The
Speaker 1: symbols he used to represent the atoms of the elements
Speaker 1: and to indicate the constitution of chemical compounds, as well
Speaker 1: as his relative weight values, are here given. This system
Speaker 1: of notation never came into general use, owing to the
Speaker 1: introduction of a simpler system by Brazilius sometime afterward. To
Speaker 1: quote his own inference, it appears that there are two
Speaker 1: oxalates of strontium, the first obtained by saturating hogxalic acid
Speaker 1: with strontium water, the second by mixing together oxalate of
Speaker 1: ammonia and mariate chloride of strontium. It is remarkable that
Speaker 1: the first contains just doubled the proportion of base contained
Speaker 1: in the second. End quote. He also investigated the potash
Speaker 1: salts of oxalic acid. Quote. Oxalated potash readily crystallizes in
Speaker 1: flat rhomboids, commonly terminated by dihedral summits. The lateral edges
Speaker 1: of the prism are usually beveled. At the temperature of
Speaker 1: sixty degrees, it dissolves and thrice its weight of water.
Speaker 1: This salt combines with an excess of acid and forms
Speaker 1: a superoxalate, long known by the name of saltosoril. The
Speaker 1: acid contained in this salt is very nearly double of
Speaker 1: what it contained in oxalated potash. Suppose one hundred parts
Speaker 1: of potash. If the weight of the acid necessary to
Speaker 1: convert this quantity into oxalate b x, then two x
Speaker 1: will convert it into superoxalate end quote. Similar research was
Speaker 1: done by W. H. Wallaston seventeen sixty six eighteen twenty eight,
Speaker 1: who by experiment found that in and the two compounds
Speaker 1: termed subcarbonate of potash and carbonate of potash, the proportions
Speaker 1: of carbonic acid relative to the same amount of potash
Speaker 1: were one to two. He also showed that supersulfate bisulfate
Speaker 1: of potash contains quote exactly twice as much acid as
Speaker 1: is necessary for the mere saturation of the alkali present
Speaker 1: end quote. These contributions prove the applicability of the law
Speaker 1: for salts and the importance of the relation thus made
Speaker 1: evident was in general realized by the chemists of the day.
Speaker 1: Figure twenty Dalton's graphic presentation of the elements simple figure one.
Speaker 1: Hydrogen relative weight one two, azot relative weight five three,
Speaker 1: carbon or charcoal relative weight five four, oxygen relative weight
Speaker 1: seven five, phosphorus relative weight nine six, sulfur relative weight
Speaker 1: thirteen seven, magnesia relative weight twenty eight, lime relative weight
Speaker 1: twenty three nine, soda relative weight twenty eight ten, potash
Speaker 1: relative weight forty two eleven, stron type relative weight forty
Speaker 1: six twelve, bar tea relative weight sixty eight thirteen, iron
Speaker 1: relative weight thirty eight fourteen, Zinc relative weight fifty six fifteen,
Speaker 1: copper relative weight fifty six sixteen, lead relative weight ninety
Speaker 1: five seventeen, silver relative weight one hundred eighteen, platina relative
Speaker 1: weight one hundred nineteen, gold relative weight one hundred and
Speaker 1: forty twenty mercury relative weight one sixty seven. Binary number
Speaker 1: twenty one. An atom of water or steam composed of
Speaker 1: one of oxygen and one of hydrogen, retained in physical
Speaker 1: context by a strong affinity, and supposed to be surrounded
Speaker 1: by a common atmosphere of heat relative weight eight twenty two.
Speaker 1: An atom of ammonia composed of one of azote and
Speaker 1: one of hydrogen, relative weight six twenty three. An atom
Speaker 1: of nitrous gas one azote plus one oxygen relative weight
Speaker 1: twelve twenty four. An atom of olefiant gas one carbon
Speaker 1: plus one hydrogen relative weight six twenty five, an atom
Speaker 1: of carbonic oxide one carbon plus one oxygen relative weight
Speaker 1: twelve ternary twenty six. An atom of nitrous oxide two
Speaker 1: azote plus one oxygen relative weight seventeen twenty seven, an
Speaker 1: atom of nitric acid one azote plus two oxygen relative
Speaker 1: weight nineteen twenty eight, an atom of carbonic acid one
Speaker 1: carbon plus two oxygen relative weight nineteen twenty nine. An
Speaker 1: atom of carbureated hydrogen one carbon plus two hydrogen relative
Speaker 1: weight sixteen quaternary number thirty. An atom of oxynitric acid
Speaker 1: one azote plus three oxygen twenty six thirty one. An
Speaker 1: atom of sulfuric acid one sulfur plus three oxygen relative
Speaker 1: weight thirty four thirty two. An atom of sulfurated hydrogen
Speaker 1: one sulfur plus three hydrogen relative weight sixteen thirty three.
Speaker 1: An atom of alcohol three carbon plus one hydrogen relative
Speaker 1: weight sixteen quinquinary and sextenary number thirty four. An atom
Speaker 1: of nitrous acid one nitric acid plus one nitrous gas
Speaker 1: relative weight thirty one, thirty five. An atom of acetous
Speaker 1: acid two carbon plus two water relative weight twenty six,
Speaker 1: Septenary number thirty six, an atom of nitrate of ammonia
Speaker 1: one nitric acid plus one ammonia plus one water relative
Speaker 1: weight thirty three, thirty seven. An atom of sugar one
Speaker 1: alcohol plus one carbonic acid, relative weight thirty five. It
Speaker 1: is now necessary to discuss the position which Davy and Gaylussat,
Speaker 1: among others, held respecting Dalton's atomic theory, as well as
Speaker 1: to narrate their services to chemistry in general. Humphrey Davy,
Speaker 1: the son of an engraver, was born at Penzance in
Speaker 1: seventeen seventy eight. The family circumstances were somewhat impecunious, and
Speaker 1: at the age of seventeen he was apprenticed to a
Speaker 1: surgeon apothecary in his native town Fig. Twenty one preparation
Speaker 1: of nitrous oxide. At the age of twenty he was
Speaker 1: placed in charge of the laboratory of the Pneumatic Institute
Speaker 1: at Bristol, founded by beatos for the application of gases
Speaker 1: to the treatment of diseases. Davy's environments here were most
Speaker 1: propitious for a successful career of scientific research. His laboratory
Speaker 1: was well furnished and was supported by the subscriptions of
Speaker 1: scientific men. He had plenty of time at his disposal,
Speaker 1: and the age was one of discovery and rapid progress
Speaker 1: in science. His experiments were related chiefly to nitrogen monoxide
Speaker 1: or nitrous oxide, and in a short time he published
Speaker 1: his quote Researches Chemical and Philosophical, chiefly concerning nitrous oxide
Speaker 1: and its respiration endquot His courage and determination were well
Speaker 1: proved by these experiments. The effect of this gas, supposed
Speaker 1: to be poisonous, were tried upon himself. He discovered its
Speaker 1: anesthetic action. He then subjected himself similarly to the action
Speaker 1: of hydrogen, nitrogen, and carbonic acid. In eighteen oh one,
Speaker 1: Davy left Bristol to become a lecturer at the Royal Institution,
Speaker 1: and two years later was elected Fellow of the Royal Society.
Speaker 1: He was soon a necessary figure in the fashionable life
Speaker 1: of the day. His auditors of the Royal Institution were
Speaker 1: numbered by the thousand. His name was on everybody's lips.
Speaker 1: It was Cooleridge who said, quote, I attended Davy's lectures
Speaker 1: to increase my stock of metaphors end quote. He was
Speaker 1: knighted in eighteen eleven and created baronet in eighteen twelve.
Speaker 1: A terrible mining disaster at Felling brought him an invitation
Speaker 1: from the governors of the Mind to investigate the conditions
Speaker 1: of such occurrences, and after an extended investigation into the
Speaker 1: nature of marsh gas in its different admixtures with air,
Speaker 1: he projected his well known safety lamp. This is about
Speaker 1: one instance out of many of his scientific insights being
Speaker 1: turned to material advantage. Davy was elected President of the
Speaker 1: Royal Society in eighteen twenty and died at Geneva in
Speaker 1: eighteen twenty nine. At the Royal Institution, Davy had at
Speaker 1: his command an excellent electric battery, and as he had
Speaker 1: for some time considered that the most needed step in
Speaker 1: chemistry was the decomposition of some of the substances them
Speaker 1: regarded as elementary, he thought that this was the most
Speaker 1: promising means for the solution of the question. In seventeen
Speaker 1: ninety Galvani made his well known experiment, and ten years
Speaker 1: later Volta invented his electric cell. These were important elements
Speaker 1: in the inquiry which went to correlate chemical and electrical phenomena,
Speaker 1: and the perception that a close relation existed between electrical
Speaker 1: force and chemical reaction spread rapidly at the beginning of
Speaker 1: the nineteenth century, after the decomposition of water into its
Speaker 1: constituents by the galvanic current had been proved by Nicholson
Speaker 1: and Carlisle in eighteen hundred, and that of salts into
Speaker 1: their bases and asses by Verzelius and Hissinger in eighteen
Speaker 1: o three. The most important of the many and varied
Speaker 1: observations on the deportment of chemical compound when subject to
Speaker 1: the actions of the current, however, were made by Davy,
Speaker 1: and his discoveries entitled him to be regarded as the
Speaker 1: pioneer of electrochemistry, as well as one of the most
Speaker 1: brilliant chemists the world has ever seen. Davy was among
Speaker 1: the first to investigate the question of the decomposition of water.
Speaker 1: This work was begun in eighteen hundred in his Mecarrion
Speaker 1: lecture delivered before the Royal Society in eighteen o six,
Speaker 1: the subject of which was on some chemical agencies of
Speaker 1: electricity is found an investigation concerning the products of the
Speaker 1: electrolysis of water. Besides hydrogen and oxygen, there was also
Speaker 1: formed acid and alkali. Davy states this is a fact. Quote.
Speaker 1: The appearance of acid and alkaline matter and water acted
Speaker 1: on by a current of electricity at the opposite electrified
Speaker 1: metallic surfaces was observed in the first chemical experiments made
Speaker 1: with a column of volta end quote. The problem requiring solution,
Speaker 1: then was to ascertain whether the acid and alkali were
Speaker 1: derived from the water, and if not, whence they came.
Speaker 1: Davy therefore proceeded to carry out as electrolysis in vessels
Speaker 1: of various materials, and to show that the products mentioned
Speaker 1: the acid and the alkali were due to the glass,
Speaker 1: or to the matter dissolved in the water, or to
Speaker 1: the air itself. If the water distilled in silver was
Speaker 1: electrolyzed in gold vessels in an atmosphere of hydrogen, the
Speaker 1: acid and alkali did not appear. To give his own description, quote,
Speaker 1: I repeated the experiment under more conclusive circumstances. I arranged
Speaker 1: the apparatus as before gold cones and water distilled in
Speaker 1: silver vessels. I exhausted the receiver and filled it with
Speaker 1: hydrogen gas from a convenient air holder. I made a
Speaker 1: second exhaustion and again introduced hydrogen that had been carefully prepared.
Speaker 1: The process was conducted for twenty four hours, and at
Speaker 1: the end of this time neither of the portions of
Speaker 1: the water altered in the slightest degree the tint of litmus.
Speaker 1: It seemed evident that that water chemically pure is decomposed
Speaker 1: by electricity into gaseous matter, into oxygen and hydrogen. He
Speaker 1: next investigated the decomposition of salt solutions and found confirmation
Speaker 1: of the statements of Brazilius and his singer. But he
Speaker 1: proceeded with still greater circumspection and sought to follow up
Speaker 1: the phenomena more exactly. All the means were at his command,
Speaker 1: and he did not hesitate to avail himself of them. Fig.
Speaker 1: Twenty two Davy's Apparatus for electrolysis of water A and
Speaker 1: B electrodes c strands of asbestos. Direct observations proved to
Speaker 1: Davy the hydrogen, the alkali, the metals, et cetera, are
Speaker 1: separated by means of the current at the negative pole
Speaker 1: and oxygen and the acids at the positive pole. From this,
Speaker 1: he concluded that the former substances possess a positive while
Speaker 1: oxygen and the acids possess a negative electrical energy, that
Speaker 1: in this case, as usual, the oppositely electrified bodies attract
Speaker 1: each other, and that in consequence, the positive substances separate
Speaker 1: at the negative pole, and vice versa. In this assumption,
Speaker 1: Davy had arrived at an explanation of the phenomena of
Speaker 1: decomposition observed in the galvanic circuit. But he proceeded a
Speaker 1: step further and endeavored to refer all chemical combinations and
Speaker 1: decomposition to similar causes. According to him, the heat observed
Speaker 1: in certain cases of decomposition were manifestations of electricity. On
Speaker 1: November nineteenth, eighteen o seven, Davy delivered an account to
Speaker 1: the Royal Society of his most recent work on the
Speaker 1: nature of the alkalies. He had made an attempt to
Speaker 1: decompose them by the electrolysis of their aqueous solutions, but
Speaker 1: without success. He had then passed a powerful current through
Speaker 1: solid potash fused of flame, and had observed a most
Speaker 1: intense light at the negative pole, due probably to the
Speaker 1: combustion of the element he was seeking, and his next
Speaker 1: experiment was decisive to give his own description. Quote. A
Speaker 1: small piece of pure potash, which had been exposed for
Speaker 1: a few seconds to the atmosphere so as to give
Speaker 1: conducting power to the surface, was placed upon an insulated
Speaker 1: dish of platina connected with the negative side of a
Speaker 1: powerful battery. The positive pole was brought in contact with
Speaker 1: the upper surface of the alkali. Unpassing the current, the
Speaker 1: potash began to fuse at both its points of electrical action.
Speaker 1: There was a violent effervescence at the upper surface. At
Speaker 1: the lower negative surface, there was no liberation of elastic fluid,
Speaker 1: but small globules having a high metallic luster appeared end quote.
Speaker 1: And he had treated soda in the same manner with
Speaker 1: similar results. Quote. It appears he said that in these
Speaker 1: facts there is evidence for the decomposition of potash and
Speaker 1: soda into oxygen and two peculiar substances. To these two
Speaker 1: peculiar substances, he gave the names potassium and sodium. In
Speaker 1: eighteen oh eight, Davy had decomposed hydrochloric acid by means
Speaker 1: of potassium, and in this way had obtained hydrogen and
Speaker 1: potassium chloride, the latter of which he had also prepared
Speaker 1: by burning potassium and chlorine. He proved in eighteen oh
Speaker 1: nine that the chlorides, myriates other metals are not decomposed
Speaker 1: by heating them with calcium metaphosphate or with silicic anhydride,
Speaker 1: but the decomposition at once begins when aqueous vapor is
Speaker 1: conducted over the mixture. Davy considered that Henry's hypothesis furnish
Speaker 1: the explanation of these experiments, and the hydrochloric acid could
Speaker 1: only be separated as soon as the quantity of water
Speaker 1: necessary for its existence was supplied. About the same time,
Speaker 1: Galuszacinthanid showed that water is produced as well as silver
Speaker 1: chloride by the action of this acid upon silver oxide,
Speaker 1: and as formerly they assumed that this water was already
Speaker 1: present in the hydrochloric acid. They then affected the synthesis
Speaker 1: of the acid by exposing a mixture of chlorine and
Speaker 1: hydrogen to sunlight. On this occasion, they advanced a complete
Speaker 1: theory regarding hydrochloric acid and chlorine, by means of which
Speaker 1: they were able to explain all their experiments. According to them,
Speaker 1: hydrochloric acid was a compound of an unknown radical maraticum
Speaker 1: with oxygen and water. Chlorine, on the other hand, was
Speaker 1: anhydrous hydrochloric acid combined with more oxygen. Davinext sought to
Speaker 1: find the oxygen which was assumed to be present in
Speaker 1: oxymeriatic acid, but by no means whatever could he abstract
Speaker 1: the oxygen from this compound. A succession of electric sparks
Speaker 1: produced no effect. Needed it strongly ignited carbon. If the
Speaker 1: gas were oxidide meriatic acid, phosphorus and sulfur might be
Speaker 1: expected to combine with the oxygen and aliberate the meriatic acid.
Speaker 1: No such result had been obtained, however, and the oily
Speaker 1: liquids which were produced only yielded mariatic acid. On the
Speaker 1: addition of water, the oxymeyriatic acid. When past ever, oxides
Speaker 1: of potassium, barium, and other metals produced meriates with evolution
Speaker 1: of precisely that amount of oxygen contained in the oxides.
Speaker 1: Referring to this experiment, Davy remarks, quote it is contrary
Speaker 1: to some logic to say that the exact quantity of
Speaker 1: oxygen is given off from a body not known to
Speaker 1: be compound when we are certain of its existence. In
Speaker 1: another end quote, He therefore explained these facts by regarding
Speaker 1: oxidized mariatic acid as an elementary substance and mariatic acid
Speaker 1: as its compound with hydrogen. But chemists hesitated upon accepting
Speaker 1: his views. Davy maintained that this element to which he
Speaker 1: gave the name chlorine, resembled oxygen in many respects, and
Speaker 1: in a limited sense was also to be regarded as
Speaker 1: an acidifier and supporter of combustion. The work of Davy
Speaker 1: was clear and brought conviction, and by eighteen twenty his
Speaker 1: theory of the nature of chlorine was generally accepted, but
Speaker 1: oxygen could no longer be regarded as the sole acid
Speaker 1: making principle, and this necessitated a new theory of acids.
Speaker 1: A French saltpeter manufacturer Courtois in eighteen eleven discovered a
Speaker 1: particular substance in the soda obtained from sea plants. He
Speaker 1: related his observation to Clement, who showed the body in
Speaker 1: question to Davy. Davy soon demonstrated its elementary nature and gayalisac,
Speaker 1: after a complete investigation of iodine as he termed it
Speaker 1: and its compounds, succeeded in showing its marked likeness to chlorine.
Speaker 1: Bromine was discovered by Rillard in eighteen twenty six in
Speaker 1: the mother liquid of sea water. Hydrofluoric acid resisted all
Speaker 1: attempts to isolate its radical, but Anpure's suggestion that it
Speaker 1: was constituted similarly to meratic acid found general acceptance. From
Speaker 1: his observation, the iotic anahydride was devoid of acid properties
Speaker 1: that acquired them after combination with water. Davy arrived at
Speaker 1: the conclusion that hydrogen and at oxygen was the acidifying
Speaker 1: principle in the latter compound. Hydrogen, in his opinion, was
Speaker 1: an essential constituent of all acids. The assumption that hydrated
Speaker 1: acids and salts contained water or metallic oxides together with
Speaker 1: acid anhydrides, he held to be unproven and unnecessary. The
Speaker 1: French chemist de Long expressed himself in a like manner
Speaker 1: after an investigation of oxolic acid and its salts, and
Speaker 1: the former he looked upon as a compound of hydrogen
Speaker 1: with carbonic acid, while in the latter he assumed in
Speaker 1: an analogous combination of metals with the elements of carbonic acid.
Speaker 1: The principles of a new theory of acids was therefore
Speaker 1: included in the discussion of Davy and Doulong, but it
Speaker 1: is to be deplored that they did not follow them
Speaker 1: up sufficiently, as otherwise they might have prevented the distinction
Speaker 1: which now began to be drawn between acids containing the
Speaker 1: oxygen and those which did not. With regard to Davy's
Speaker 1: attitude to the atomic theory of Dalton, it should first
Speaker 1: be mentioned that he asserted in eighteen oh nine that
Speaker 1: William Higgins was the originator of this doctrine. The latters
Speaker 1: a comparative view of the flogistic and antiflogistic theories with
Speaker 1: inductions seventeen eighty nine, Davy maintained contained use similar to
Speaker 1: those of Dalton, but later he recognized Dalton's service. Davy
Speaker 1: regarded Dalton's atomic weights as simply the proportion numbers of
Speaker 1: the elements, and maintained that there was no positive basis
Speaker 1: upon which to proceed for the determination of the atomic weights.
Speaker 1: Two other investigators of this time, Walistan and gay Lusac,
Speaker 1: also refused to admit that Dalton's atomic weights were really such.
Speaker 1: Previous to Davie, Walliston had asserted that there was the
Speaker 1: chemical equivalence of the elements, while Gayalisak could not concede
Speaker 1: that the ratio of one element to another was fixed
Speaker 1: by analytical and synthetical determinations. His laws of combining volumes
Speaker 1: had a definite bearing on the atomic theory, however, and
Speaker 1: this generalization, along with his work and analytical chemistry and
Speaker 1: numerous researches in inorganic chemistry, rendered further notice of him necessary.
Speaker 1: Joseph Luis gay Lussac seventeen seventy eight eighteen fifty was
Speaker 1: a student of Bertolat and in eighteen oh nine became
Speaker 1: professor of chemistry at the Ecole Polytechnique, at the same
Speaker 1: time holding the chair of physics at the Suborne. In
Speaker 1: eighteen thirty two he accepted the chariff chemistry at the
Speaker 1: Jaudine des Plante. Gay Lussac was a masterly investigator, capable
Speaker 1: of the most accurate analytical work and exact in observation,
Speaker 1: and enriched chemistry with many valuable researches. Of especial importance
Speaker 1: was his work on idine and its compounds, on cyanogen,
Speaker 1: which he characterized as the first compound radical, on sulfur
Speaker 1: and its compounds, on the oxides of nitrogen, on the
Speaker 1: isolation of boron, and his conjoint investigation with LJ. Thanard
Speaker 1: on the alkali metals and with Libig on the fulminates.
Speaker 1: He also introduced improved methods of inorganic and organic analysis,
Speaker 1: and is to be regarded as having laid the foundation
Speaker 1: of volumetric analysis. His name is particularly associated, however, with
Speaker 1: his investigations on the combining volumes of gases. In eighteen
Speaker 1: oh five, Gala Sac and Alexander von Humboldt published in
Speaker 1: mamoir entitled Experiments in the Ratio of the Constituents of
Speaker 1: the Atmosphere, in which they announced that they had found
Speaker 1: the volume ratio hydrogen to oxygen two hundred to one hundred.
Speaker 1: This led Gayli Sac to extend his investigations to the
Speaker 1: volume relationships of other gaseous substances, which are compounds of
Speaker 1: gaseous constituents, and by the close of the year eighteen
Speaker 1: oh eight he was able to announce results which showed
Speaker 1: the existence of a simple and general law. He summarizes
Speaker 1: his results as follows quote. I have shown in this
Speaker 1: memoir that the compounds of gaseous substances with which other
Speaker 1: are always formed in very simple ratios, so that representing
Speaker 1: one of the terms by unity, the other is one
Speaker 1: or two or at most three. These ratios by volume
Speaker 1: are not observed with solid or liquid substances, nor when
Speaker 1: we consider weights, and they form a new proof that
Speaker 1: is only in the gaseous state, that substances are in
Speaker 1: the same circumstances and obey regular laws. The apparent contraction
Speaker 1: of volume suffered by gases on combination is also very
Speaker 1: simply related to the volume of one of them, and
Speaker 1: this property likewise is peculiar to gaseous substances end quote.
Speaker 1: This law of combining volumes as stated by Oswald in
Speaker 1: his Outlines of General chemistry, as follows quote. If gaseous
Speaker 1: substances enter into chemical combinations, their volumes are in simple
Speaker 1: rational proportions, and if a gaseous substance is formed by
Speaker 1: their union, its volume also is rationally related to the
Speaker 1: volumes of the original gases end quote. Gaylasak was himself
Speaker 1: inclined to conjoin his law of volumes with the atomic theory, indeed,
Speaker 1: he reckoneded in it as support for the latter. A
Speaker 1: similar molecular condition was essential, however, in order that all
Speaker 1: gases should deport themselves alike toward pressure and changes of temperature,
Speaker 1: and besides obey his law of volumes. In other words,
Speaker 1: equal volumes of gases must contain equal numbers of molecules.
Speaker 1: Galu sc drew no distinction between these molecules and atoms,
Speaker 1: recognizing but one kind of final particle. Dalton opposed this
Speaker 1: reasoning and stated that he had held the same view
Speaker 1: as to combining volumes at one time, but finally saw
Speaker 1: that it was untenable to quote from his a new
Speaker 1: system of chemical philosophy. At the time I formed the
Speaker 1: theory of mixed gases, I had a confused idea, as
Speaker 1: many have. I supposed at this time that the particles
Speaker 1: of elastic foods were all of the same size, that
Speaker 1: a given volume of oxygenous gas contained just as many
Speaker 1: particles as the same volume as hydrogens. But I became
Speaker 1: convinced that different gases have not their particles of the
Speaker 1: same size, and that the following may be adopted as
Speaker 1: a maxim till some reason appears to the contrary, namely,
Speaker 1: that every species of pure elastic fluid has its particles
Speaker 1: globular and all of a size, but no two species
Speaker 1: agree in the size of the particles, the pressure and
Speaker 1: temperature being the same end quote. He also maintained that
Speaker 1: gases do not combine exactly by volumes, but frequently by
Speaker 1: fractions of volumes. He said, quote, The truth is, I
Speaker 1: believe that gases do not unite in equal or exact
Speaker 1: measures in any one instance. When they appear to do so,
Speaker 1: it is owing to the inaccuracy of our experiments. In
Speaker 1: no case, perhaps is there a nearer approach of mathematical
Speaker 1: exactness than in that of one measure of oxygen to
Speaker 1: two of hydrogen. But here the most exact experiments I
Speaker 1: have ever made gave one point ninety seven hydrogen to
Speaker 1: one oxygen end quote. His argument may be illustrated as follows.
Speaker 1: Taking hydrochloric acid as an example, one atom of hydrogen
Speaker 1: chloride consists of one atom of hydrogen and one atom
Speaker 1: of chlorine. Then if equal volumes of gases contain equal
Speaker 1: numbers of molecules, one volume of hydrogen and one volume
Speaker 1: of chlorine should produce one volume of hydrogen chloride, but
Speaker 1: they really form two. Consequently, each one of these can
Speaker 1: contain only half as many atoms as the original volumes
Speaker 1: of the constituents. Such ratios nation is manifestly conclusive as
Speaker 1: far as the theory of the volumes containing the same
Speaker 1: number of atoms is concerned unless some different definition of
Speaker 1: atoms is assumed. The connection between Gales Sax law of
Speaker 1: volumes and Dalton's atomic theory was shown by the U
Speaker 1: Italian physicist Amideo Avogadro seventeen seventy six eighteen fifty six.
Speaker 1: In eighteen eleven, Avagadro discarded Dalton's artificial distinction between the
Speaker 1: ultimate particles of a compound and those of an element,
Speaker 1: and made a distinction between what he termed molecules integrants
Speaker 1: and molecules elementaire or molecules in atoms, the former being
Speaker 1: compound particles made up of the indivisible atoms. The researches
Speaker 1: of Galusac indicate then that a molecule of water consists
Speaker 1: of one molecule of hydrogen and one half molecule of oxygen.
Speaker 1: A molecule of hydrogen chloride consists of one half molecule
Speaker 1: of hydrogen and one half molecule of chlorine, and so
Speaker 1: the difficulty pointed out by Dalton was efface from chemical literature.
Speaker 1: Av Agadro's assumption that equal volume of gases elementary or
Speaker 1: at the same temperature and pressure contain equal number of molecules.
Speaker 1: Although only a hypothesis is generally referred to as Avogadro's law,
Speaker 1: it is of fundamental importance to chemistry. He also stated
Speaker 1: that the relative weights of gaseous molecules may be determined
Speaker 1: by the measurement of the relative weights of equal volumes
Speaker 1: of the gaseous substances, that is, by comparison of gaseous densities,
Speaker 1: and that the number of gaseous volumes interacting indicates the
Speaker 1: relative number of molecules interacting, and similarly, the volume of
Speaker 1: the compound gas formed, when compared with that of the constituents,
Speaker 1: gives the number whole or fractional of elementary molecules entering
Speaker 1: into the composition of one compound molecule. Avigadro's conclusions produced
Speaker 1: practically no effect at the time they were promuligated, and
Speaker 1: fifty years passed by before they were received with due recognition.
Speaker 1: These conclusions of Avogadro are sometimes add to the French
Speaker 1: mathematician Ampier seventeen seventy five eighteen thirty six, but the
Speaker 1: memoir of the latter did not appear until eighteen fourteen
Speaker 1: and is much less important than that of Avogadra while
Speaker 1: Davy and Gali Sik were conducting their valuable investigations. An
Speaker 1: important literary chemical event, most impressive and attractive in nature,
Speaker 1: occurred when William Prout seventeen eighty five eighteen fifty advanced
Speaker 1: his hypothesis of the genesis of the elements. In eighteen fifteen,
Speaker 1: in a paper upon the relations between specific gravities of
Speaker 1: bodies in the gaseous state and their atomic weights, Pratt
Speaker 1: stated that he had often observed the close approximation to
Speaker 1: round numbers of many of the weights of the atoms
Speaker 1: from the table at his command. He further deduced that
Speaker 1: all elementary numbers hydrogen being considered as one, are divisible
Speaker 1: by four, except carbon, nitrogen, and barium, and these are
Speaker 1: divisible by two, appearing therefore or to indicate that they
Speaker 1: are modified by a higher number than unity of hydrogen.
Speaker 1: He considered the other numbers might be sixteen or oxygen,
Speaker 1: and that possibly all substances were composed of these two elements.
Speaker 1: A short time after, in eighteen sixteen, he expressed the
Speaker 1: following views quote. If the views we have ventured to
Speaker 1: advance be correct, we may almost consider the protely of
Speaker 1: the ancients to be realized in hydrogen, an opinion by
Speaker 1: the Bye not altogether new if we actually consider this
Speaker 1: to be the case, and further consider the specific gravities
Speaker 1: of bodies in their gaseous states to represent the number
Speaker 1: of volumes condensed into one or in other words, the
Speaker 1: number of the absolute weights of a single volume of
Speaker 1: the first matter protely which they contain, which is extremely probable.
Speaker 1: Multiples in weight must also indicate multiples in volume, and
Speaker 1: vice versa, and the specific gravities or absolute weights of
Speaker 1: all bodies in the gaseous state must be multiples of
Speaker 1: the specific gravity or absolute weight of the first matter,
Speaker 1: because all bodies in a gaseous state which unite with
Speaker 1: one another unite with reference to this volume. En Prout's
Speaker 1: conjecture was taken up by Thomas Thompson, who, being carried
Speaker 1: away by the attraction of simplicity, became the advocate of
Speaker 1: a philosophical speculation contrary to experimental facts, and even perceived
Speaker 1: in it a fundamental law of chemistry. Other chemists, too,
Speaker 1: showed a predilection for Prout's hypothesis, and notwithstanding the fact
Speaker 1: that Brazilius and Turner demonstrated its unattainability. Some exact investigators
Speaker 1: as late as eighteen forty betrayed an inclination to some
Speaker 1: of Prout's views. In fact, some writers of the present
Speaker 1: day consider that there may be a kernel of truth
Speaker 1: concealed in it, and although it has suffered numerous reversals,
Speaker 1: it is still revived at intervals. End of Chapter ten