WEBVTT 1 00:00:00.240 --> 00:00:04.719 Section fifteen of the Science History of the Universe, Volume four. 2 00:00:05.480 --> 00:00:09.960 This is a LibriVox recording. All LibriVox recordings are in 3 00:00:10.039 --> 00:00:14.839 the public domain. For more information or to volunteer, please 4 00:00:14.960 --> 00:00:20.239 visit LibriVox dot org. Recording by Lawrence Trask, Mount Vernon, 5 00:00:20.280 --> 00:00:26.760 Ohio interface audio dot com. The Science History of the Universe, 6 00:00:26.920 --> 00:00:34.000 Volume four, edited by Francis Rolt Wheeler. Chemistry, Chapter eleven, 7 00:00:34.280 --> 00:00:39.840 Bersilius and the development of the atomic theory. Complete success 8 00:00:39.960 --> 00:00:44.000 had rewarded the exertions of Lavossier, and through the efforts 9 00:00:44.000 --> 00:00:48.880 of Praust Richter, Dalton, gayla Sac and Davy, the spirit 10 00:00:48.920 --> 00:00:52.240 of order was creeping in on all sides. But it 11 00:00:52.320 --> 00:00:56.560 was exceedingly fortunate for chemistry that an investigator with the 12 00:00:56.640 --> 00:01:01.079 sense of coordination that Bersilius possessed should have made his 13 00:01:01.280 --> 00:01:05.920 advent just at this time when laws required confirmation and 14 00:01:06.040 --> 00:01:12.280 theories nourishment. The foundations of the new system required extension 15 00:01:12.400 --> 00:01:17.000 and generalization, And how opportune was the appearance of one 16 00:01:17.200 --> 00:01:22.000 who could illumine the whole domain of chemistry. Brasilius ruled 17 00:01:22.040 --> 00:01:25.120 as an autocrat for over a quarter of a century, 18 00:01:25.640 --> 00:01:30.000 and the modern chemist can hardly over extol his obligation 19 00:01:30.200 --> 00:01:37.719 to him John's Jacob Bersilius was born at Walversunda in Ostergotland, Sweden, 20 00:01:38.040 --> 00:01:42.239 on August twentieth, seventeen seventy nine. His father was a 21 00:01:42.239 --> 00:01:46.519 schoolmaster in Linkoping and died four years after the birth 22 00:01:46.560 --> 00:01:49.920 of his son, who for some time afterward had to 23 00:01:50.159 --> 00:01:57.760 endure many privations. Brasilius studied medicine at Uppsala and subsequently practiced, 24 00:01:58.200 --> 00:02:01.079 but he had early acquired it a vote to chemistry 25 00:02:01.400 --> 00:02:04.359 and kept in close touch with it. He was but 26 00:02:04.480 --> 00:02:09.000 twenty when he undertook his first extensive chemical research, an 27 00:02:09.000 --> 00:02:13.159 investigation of the medical springs at mediev in the neighborhood 28 00:02:13.159 --> 00:02:17.360 of his birthplace. A short time after, in eighteen oh two, 29 00:02:17.400 --> 00:02:21.960 in conjunction with Heisinger, he commenced the examination of the 30 00:02:22.000 --> 00:02:26.280 action of the electric current on varioussaults, with the most 31 00:02:26.360 --> 00:02:32.159 far reaching results for chemistry and for himself. For almost immediately. 32 00:02:32.439 --> 00:02:35.759 The desire to keep so promising a student in Stockholm 33 00:02:36.120 --> 00:02:40.280 induced the authorities to create for him a new academic position, 34 00:02:41.000 --> 00:02:45.639 that of Assistant Professor of Medicine, Botany and Pharmacy at 35 00:02:45.639 --> 00:02:50.080 the University of Stockholm. In eighteen oh seven he was 36 00:02:50.080 --> 00:02:53.719 installed in the chair of Medicine and Pharmacy, and also 37 00:02:53.759 --> 00:02:57.479 taught chemistry at the Military College from the year eighteen 38 00:02:57.520 --> 00:03:01.439 oh six. In eighteen fifteen he accepted the chair of 39 00:03:01.520 --> 00:03:05.919 Chemistry in the Scherergico Medical Institute of Stockholm, where he 40 00:03:05.960 --> 00:03:10.000 accomplished the researches which made him famous, and where his 41 00:03:10.120 --> 00:03:13.919 lectures enabled him to impress his views upon the rising 42 00:03:14.000 --> 00:03:18.960 generation of chemists. Among his pupils may be mentioned Heinrich 43 00:03:19.000 --> 00:03:25.560 and Gustav Rose, Mitcherlich, Whohler, Christian gautleb Melen, Magnus, Mozander 44 00:03:25.919 --> 00:03:30.759 Zanberg and Cefstrom. From the year eighteen eighteen, when he 45 00:03:30.840 --> 00:03:35.120 was nominated permanent secretary to the Stockholm Academy, of which 46 00:03:35.159 --> 00:03:37.560 he had been a member since eighteen o eight, and 47 00:03:37.759 --> 00:03:42.479 more particularly after eighteen thirty two, when Mozender succeeded him 48 00:03:42.560 --> 00:03:47.240 in his chair. Brazilius devoted himself to literary work with 49 00:03:47.319 --> 00:03:51.319 a subservience which has hardly been equalled from a utilitarian 50 00:03:51.400 --> 00:03:56.560 standpoint by any chemist before or after him. He died 51 00:03:56.599 --> 00:04:01.159 on the seventh of August eighteen forty eight. Brasilius was 52 00:04:01.199 --> 00:04:06.240 an exceptional observer and a most accurate and operose investigator, 53 00:04:06.919 --> 00:04:11.400 exhibiting very close attention to details. It is difficult to 54 00:04:11.479 --> 00:04:15.159 render an account of his achievements, as they extended over 55 00:04:15.280 --> 00:04:19.639 almost the entire field of chemistry and produced reforms of 56 00:04:19.720 --> 00:04:24.480 great importance. And one must not forget that the laboratory 57 00:04:24.560 --> 00:04:29.199 in which Brasilius accomplished his famous researches was small and 58 00:04:29.399 --> 00:04:34.319 imperfectly equipped. To give Wohler's description of his first visit 59 00:04:34.399 --> 00:04:38.639 to it, no water, no gas, no hoods, no oven 60 00:04:38.879 --> 00:04:42.879 were to be seen. A couple of plain tables, a blowpipe, 61 00:04:43.199 --> 00:04:47.839 a few shelves with bottles, a simple apparatus, and a 62 00:04:47.959 --> 00:04:52.480 large water barrel whereat. Anna, the ancient cook of the establishment, 63 00:04:53.040 --> 00:04:57.160 washed the laboratory dishes, completed the furnishings of this room, 64 00:04:57.399 --> 00:05:00.800 famous throughout Europe for the work which had been done 65 00:05:00.800 --> 00:05:05.199 in it. In the kitchen, which adjoined and where Anna cooked, 66 00:05:05.759 --> 00:05:09.560 was a small furnace and a sand bath for heating purposes. 67 00:05:10.399 --> 00:05:15.639 Brasilius introduced many improvements in analytical chemistry. It was he 68 00:05:15.720 --> 00:05:19.680 who first employed fall smaller amounts of substances than the 69 00:05:19.800 --> 00:05:24.360 large quantities recommended by Claproth, who introduced the spirit lamp 70 00:05:24.439 --> 00:05:28.759 which bears his name, thereby rendering the incineration of filter 71 00:05:28.879 --> 00:05:33.439 paper and the ignition of precipitates facile, and who worked 72 00:05:33.480 --> 00:05:37.920 out many new methods of analysis. Among the latter were 73 00:05:38.000 --> 00:05:42.120 his plan of decomposing silicates by the aid of chlorine. 74 00:05:43.079 --> 00:05:47.879 He enriched mineralogy by many analyses of minerals and mineral waters, 75 00:05:48.399 --> 00:05:51.279 and in a number of these, for example those of 76 00:05:51.360 --> 00:05:57.480 platinum ores, he devised new methods of separation. Brasilius was 77 00:05:57.600 --> 00:06:01.639 the first to characterize minerals as being in every respect 78 00:06:01.959 --> 00:06:08.079 chemical compounds, and he classified them similarly to substances prepared artificially. 79 00:06:09.000 --> 00:06:11.680 He was also able to demonstrate that the doctrine of 80 00:06:11.800 --> 00:06:17.959 chemical proportions and consequently the atomic theory, was applicable to minerals. 81 00:06:18.920 --> 00:06:23.319 The close attention which Bersilius gave to details resulted in 82 00:06:23.399 --> 00:06:28.720 the discovery of selenium eighteen seventeen, therhea eighteen twenty eight, 83 00:06:29.120 --> 00:06:33.319 and in conjunction with Heisinger and independent of Klaproth, he 84 00:06:33.360 --> 00:06:37.560 discovered seria eighteen o three. He also discovered many new 85 00:06:37.720 --> 00:06:42.199 chemical compounds, among which were the compounds of selenium with 86 00:06:42.399 --> 00:06:48.040 hydrogen and oxygen, and some molydenum compounds. Isolated the elements 87 00:06:48.120 --> 00:06:53.560 silicon eighteen ten, zirconium and tantalum eighteen twenty four, and 88 00:06:53.800 --> 00:06:58.240 extended the knowledge of the platinum metals. Passages in the 89 00:06:58.279 --> 00:07:02.399 work of Brasilius indicate that he regarded the firm establishment 90 00:07:02.920 --> 00:07:07.000 of the doctrine of chemical proportions, and in conjunction with 91 00:07:07.040 --> 00:07:10.399 this the determination of the atomic weights of the elements 92 00:07:10.759 --> 00:07:14.720 and the constitution of chemical compounds, as his main task. 93 00:07:15.839 --> 00:07:20.920 To quote from his Leerbruck Derkschemie fifth edition, I resolved 94 00:07:20.920 --> 00:07:24.160 to make the analysis of a number of salts, whereby 95 00:07:24.360 --> 00:07:28.920 that of others might become superfluous. I soon convinced myself 96 00:07:28.959 --> 00:07:32.959 by new experiments that Dalton's numbers were wanting in that 97 00:07:33.079 --> 00:07:38.319 accuracy which was requisite for the practical application of his theory. 98 00:07:38.800 --> 00:07:42.600 I recognized that if the newly arisen light was to spread, 99 00:07:43.120 --> 00:07:46.920 it would be necessary to ascertain with the utmost accuracy 100 00:07:47.360 --> 00:07:52.560 the atomic weights of all elementary substances, and particularly those 101 00:07:52.680 --> 00:07:57.000 of the more common ones. Without such work, no day 102 00:07:57.079 --> 00:08:00.759 would follow the dawn. This was their for the most 103 00:08:00.759 --> 00:08:05.240 important object of chemical investigation at the time, and I 104 00:08:05.279 --> 00:08:10.240 devoted myself to it with unresting labor, after work extending 105 00:08:10.319 --> 00:08:14.120 over ten years I was able in eighteen eighteen to 106 00:08:14.279 --> 00:08:18.480 publish a table which contained the atomic weights, as calculated 107 00:08:18.519 --> 00:08:23.759 from my experiments of about two thousand simple and compound substances. 108 00:08:24.720 --> 00:08:29.279 In the years eighteen twelve to eighteen sixteen, Brazilius investigated 109 00:08:29.279 --> 00:08:32.519 the stages of oxidation of most of the metals and 110 00:08:32.600 --> 00:08:38.080 metalloids than known, and by determining the composition of these oxides, 111 00:08:38.559 --> 00:08:43.919 confirmed the law of multiple proportions. His analytical work greatly 112 00:08:43.960 --> 00:08:48.399 surpassed that of Dalton, and in the rules established for 113 00:08:48.480 --> 00:08:51.799 his guidance in deciding the number of atoms in a 114 00:08:51.840 --> 00:08:57.399 given compound or molecule, he exhibited a far greater knowledge. Still, 115 00:08:57.519 --> 00:09:03.679 his rules were in some respects arbitrary and unsatisfactory. He 116 00:09:03.720 --> 00:09:07.919 took oxygen equals one hundred as his standard, giving as 117 00:09:07.960 --> 00:09:11.960 his reason for this preference. The following to refer the 118 00:09:12.000 --> 00:09:15.480 other atomic weights to that of hydrogen offers not only 119 00:09:15.600 --> 00:09:20.639 no advantages, but has in fact many inconveniences, seeing that 120 00:09:20.720 --> 00:09:24.919 hydrogen is very light and is seldom a constituent of 121 00:09:25.120 --> 00:09:30.200 inorganic compounds. Oxygen, on the other hand, unites all the 122 00:09:30.279 --> 00:09:34.799 advantages in itself. It is, so to speak, the center 123 00:09:34.879 --> 00:09:39.320 point round which the whole of chemistry revolves. This view 124 00:09:39.600 --> 00:09:43.000 is again at the present time held by many chemists, 125 00:09:43.360 --> 00:09:47.440 who take sixteen as the atomic weight of oxygen, and 126 00:09:47.639 --> 00:09:51.039 base the atomic weights of all the other elements upon 127 00:09:51.240 --> 00:09:56.320 this number. Brasilius began his work at the time when 128 00:09:56.440 --> 00:10:00.559 Wallaceton was attempting, by his use of the term equivalents 129 00:10:00.799 --> 00:10:05.240 to eliminate the question of atoms. Thompson was employing the 130 00:10:05.279 --> 00:10:10.200 standard oxygen equals one, considering that this number would give 131 00:10:10.360 --> 00:10:13.879 more of the atomic weights as whole numbers, and failing 132 00:10:13.919 --> 00:10:17.759 to perceive that the law of volumes had any particular 133 00:10:17.879 --> 00:10:24.080 significance from the atomic standpoint. Brazilius, however, perceived in the 134 00:10:24.159 --> 00:10:28.159 law of volumes a corroboration of the atomic theory, and 135 00:10:28.320 --> 00:10:31.240 allowed himself to be guided by it in his views 136 00:10:31.399 --> 00:10:35.840 upon the number of atoms in chemical compounds, and consequently 137 00:10:36.279 --> 00:10:41.080 upon the numerical values of the atomic weights. His volume 138 00:10:41.159 --> 00:10:45.320 Theory contained the attempt to combine gay Lussac's law with 139 00:10:45.480 --> 00:10:50.480 the atomic theory. He set forth the atomistic view, which 140 00:10:50.519 --> 00:10:53.639 he had himself put into shape under the influence of 141 00:10:53.840 --> 00:10:58.600 the law of volumes, definitely and conclusively in two papers. 142 00:10:59.360 --> 00:11:02.039 He started with the assumption that in the case of 143 00:11:02.120 --> 00:11:05.960 every simple substance, when it was in the gaseous form, 144 00:11:06.360 --> 00:11:11.039 one volume corresponded with one atom, and therefore made use 145 00:11:11.080 --> 00:11:17.559 of the designation volume atoms for those smallest particles. Wherever 146 00:11:17.639 --> 00:11:21.200 it was practicable, he attempted to measure the volumes of 147 00:11:21.240 --> 00:11:26.000 the combining substances, and from these deduced the atomic numbers. 148 00:11:26.639 --> 00:11:29.919 The analysis of the compound in which the volumes of 149 00:11:29.960 --> 00:11:34.159 the elementary constituents were known led him to the true 150 00:11:34.240 --> 00:11:39.000 determination of the atomic weights of the latter. For example, 151 00:11:39.039 --> 00:11:41.759 from the fact that water consists of two volumes of 152 00:11:41.840 --> 00:11:46.360 hydrogen and one of oxygen, he deduced the atomic composition 153 00:11:46.440 --> 00:11:49.919 of water, which holds at the present day, together with 154 00:11:50.080 --> 00:11:54.440 the relative atomic weights of oxygen and hydrogen. And from 155 00:11:54.519 --> 00:11:58.720 the mode of formation of carbonic oxide and carbonic acid 156 00:11:59.320 --> 00:12:02.879 he arrived at the true composition of these compounds, and 157 00:12:03.000 --> 00:12:06.759 at the atomic weight of carbon, and so forth. Still, 158 00:12:06.879 --> 00:12:11.240 the use which Bersilius made of gay Lussac's law was 159 00:12:11.279 --> 00:12:14.679 too limited to free him from the necessity of employing 160 00:12:14.799 --> 00:12:19.559 rules for deciding the number of atoms in compounds. In 161 00:12:19.639 --> 00:12:23.840 eighteen eighteen, Brasilius gave a table of atomic weights which 162 00:12:23.960 --> 00:12:28.559 contained values which compare favorably with those of other observers. 163 00:12:29.559 --> 00:12:33.279 Nine years later he published another table which brought his 164 00:12:33.360 --> 00:12:38.679 atomic weights still closer to those now current. The reason 165 00:12:38.799 --> 00:12:42.840 given by Brasilius for having in eighteen twenty six many 166 00:12:42.879 --> 00:12:45.679 of the atomic weights assigned to the metals in eighteen 167 00:12:45.759 --> 00:12:50.320 eighteen was as follows. It is known that the oxide 168 00:12:50.360 --> 00:12:55.440 of chromium contains three atoms of oxygen. Chromic acid, for 169 00:12:55.519 --> 00:12:59.720 the same number of chromium atoms, contains twice as much oxygen, 170 00:13:00.120 --> 00:13:03.559 which would be six atoms, but in its neutral salts, 171 00:13:03.679 --> 00:13:08.000 chromic acid neutralizes an amount of a base containing one 172 00:13:08.120 --> 00:13:12.360 third as much oxygen as it contains itself, a relation 173 00:13:12.519 --> 00:13:15.639 found to hold in the case of all acids with 174 00:13:15.879 --> 00:13:20.879 three atoms of oxygen, for example, sulphuric acid and sulfates. 175 00:13:22.000 --> 00:13:25.600 In order to harmonize the multiple relation between the amount 176 00:13:25.639 --> 00:13:29.679 of oxygen in the oxide and in the acid, it 177 00:13:29.759 --> 00:13:33.399 is most probable that the acid contains three atoms of 178 00:13:33.480 --> 00:13:38.120 oxygen to one atom of chromium, and the oxide three 179 00:13:38.159 --> 00:13:43.159 atoms of oxygen to two of chromium. Isomorphous with the 180 00:13:43.200 --> 00:13:48.080 oxide of chromium are those of manganese, iron, and aluminum. 181 00:13:49.120 --> 00:13:52.360 Those also we know to contain three atoms of oxygen, 182 00:13:52.919 --> 00:13:57.240 and consequently must represent them as containing two atoms of 183 00:13:57.320 --> 00:14:01.480 the radical. But if the fire feric oxide consists of 184 00:14:01.519 --> 00:14:06.039 two fe plus three oxygen, the ferrous oxide is fe 185 00:14:06.240 --> 00:14:10.080 plus oxygen. But if the ferric oxide consists of two 186 00:14:10.080 --> 00:14:15.320 ferric plus three oxide, the ferrous oxide is ferric plus oxide, 187 00:14:15.840 --> 00:14:20.440 and the whole series of oxides isomorphous with it contains 188 00:14:20.559 --> 00:14:24.600 one atom of the radical and one atom of oxygen. 189 00:14:26.679 --> 00:14:30.960 Thus we see that E. Mischerlich's law of isomorphism that 190 00:14:31.159 --> 00:14:35.440 compounds of analogous composition and containing the same number of 191 00:14:35.519 --> 00:14:40.840 atoms crystallize in the same crystalline form, announced in eighteen nineteen, 192 00:14:41.360 --> 00:14:45.159 and which berzelis regarded as the most important since the 193 00:14:45.279 --> 00:14:49.639 establishment of the doctrine of chemical proportions, was an aid 194 00:14:49.720 --> 00:14:54.120 in testing his atomic weight determinations, for according to him, 195 00:14:54.360 --> 00:15:01.279 isomorphism indicated similarity in atomic constitution. Brazilium further showed that, 196 00:15:01.360 --> 00:15:04.759 with the exception of cobalt and silver, the law of 197 00:15:04.840 --> 00:15:08.919 specific heat justified the change made in eighteen twenty six. 198 00:15:09.840 --> 00:15:13.399 This law was advanced in eighteen nineteen by P. L. 199 00:15:13.559 --> 00:15:18.159 De Long and TA. Pettitt, who in investigating the specific 200 00:15:18.240 --> 00:15:21.799 heats of the metals and other bodies, reached the important 201 00:15:21.840 --> 00:15:26.840 conclusion that these were very nearly inversely proportional to their 202 00:15:26.879 --> 00:15:31.679 atomic weights. Multiplied by their atomic weights, the specific heats 203 00:15:31.799 --> 00:15:35.759 gave a constant quantity. This resulted in the law as 204 00:15:35.799 --> 00:15:39.679 stated by them, the atoms of the different elements have 205 00:15:39.799 --> 00:15:43.600 the same capacity for heat. It is not difficult to 206 00:15:43.639 --> 00:15:47.080 perceive that by means of the specific heat, one could 207 00:15:47.159 --> 00:15:51.120 readily approximate the true atomic weight and arrive at a 208 00:15:51.159 --> 00:15:54.480 decision as to which of the two or more possible 209 00:15:54.519 --> 00:16:00.799 figures represented the true weight. There were exceptions to the law, 210 00:16:00.879 --> 00:16:05.039 which have been explained only in late years. However, the 211 00:16:05.120 --> 00:16:09.639 law was extended to simple chemical compounds and proved of 212 00:16:09.759 --> 00:16:15.480 great assistance after it was more fully understood. Brasilius opposed 213 00:16:15.480 --> 00:16:18.799 the acceptance of it at first, in part because it 214 00:16:18.840 --> 00:16:22.399 would necessitate a revision of his table of atomic weights 215 00:16:23.039 --> 00:16:26.519 and might endanger the accepted views as to some of 216 00:16:26.559 --> 00:16:31.519 the atomic relations. He gradually gave up this position, however, 217 00:16:31.840 --> 00:16:35.639 when the law was confirmed by other workers and more 218 00:16:35.679 --> 00:16:39.759 accurate determinations were made than the first ones of DeLong 219 00:16:39.840 --> 00:16:45.240 and Petit, Brazilius substituted for Dalton's geometrical symbols a more 220 00:16:45.320 --> 00:16:49.759 convenient system of chemical notation, which to give his own words, 221 00:16:49.919 --> 00:16:54.799 might facilitate the expression of chemical proportions. Showed briefly and 222 00:16:54.919 --> 00:16:59.240 clearly the number of elementary atoms in each compound, and, 223 00:16:59.320 --> 00:17:03.440 after the determin termination of their relative weights, present the 224 00:17:03.519 --> 00:17:07.960 results of each analysis in a simple and easily retained manner. 225 00:17:09.319 --> 00:17:12.559 The atom of each element was represented by the initial 226 00:17:12.640 --> 00:17:16.880 letter of its latinized name, a second letter being added 227 00:17:16.960 --> 00:17:20.480 when two elements had names beginning with the same capital. 228 00:17:21.440 --> 00:17:24.759 An index number was added when more than one atom 229 00:17:25.039 --> 00:17:29.559 was present. A compound was thus represented by placing the 230 00:17:29.599 --> 00:17:33.519 proper number of these symbols side by side. Thus H 231 00:17:33.640 --> 00:17:39.400 is hydrogen cl is chlorine and HCl is hydrogen chloride. 232 00:17:40.640 --> 00:17:44.880 Brazilius assumed the existence of certain double atoms. Where two 233 00:17:44.960 --> 00:17:49.079 atoms of an element occur together. These were indicated by 234 00:17:49.160 --> 00:17:52.559 a mark across the symbol. Thus H with a stroke 235 00:17:52.599 --> 00:17:56.519 through it followed by O was water, or as it 236 00:17:56.559 --> 00:18:00.680 is now written H two O for it can venient's sake. 237 00:18:01.079 --> 00:18:04.599 An atom of oxygen was often indicated by a point 238 00:18:04.880 --> 00:18:09.480 or dot. Thus, carbon dioxide C with two dots above it, 239 00:18:10.200 --> 00:18:14.680 nitrous acid N with four dots above it, potassium nitrate 240 00:18:14.920 --> 00:18:19.359 k N with three dots above the N. These symbols 241 00:18:19.440 --> 00:18:23.319 were a great advance over those suggested by Dalton, which 242 00:18:23.359 --> 00:18:29.039 were diagrammatic and quite unpractical. Dalton, however, criticized the system 243 00:18:29.079 --> 00:18:33.799 of notation of Berzelius, saying that brazilius symbols are horrifying. 244 00:18:34.440 --> 00:18:37.559 A young student in chemistry might as soon learn Hebrew 245 00:18:37.960 --> 00:18:43.400 as make himself acquainted with them. Brasilius adopted dualism as 246 00:18:43.480 --> 00:18:47.240 the basis of his chemical system. He extended the term 247 00:18:47.319 --> 00:18:51.559 atom so that it included what he regarded as compound atoms, 248 00:18:52.000 --> 00:18:55.079 which were built up of two parts, each of which 249 00:18:55.240 --> 00:18:59.119 might be a simple atom or a single simple atom. 250 00:18:59.480 --> 00:19:03.519 This was the dual structure which dominated all his views 251 00:19:03.559 --> 00:19:07.200 with regard to chemical phenomena, and far more than a 252 00:19:07.240 --> 00:19:12.319 decade held a pre eminent position in chemistry. Brazilius seemed 253 00:19:12.359 --> 00:19:16.519 to have formed this idea of dualism from his observations 254 00:19:16.599 --> 00:19:20.519 upon the volumes of gases. For a certain number of 255 00:19:20.559 --> 00:19:25.240 these gases, the equivalent is formed of two atoms. This 256 00:19:25.400 --> 00:19:29.440 was true not only of hydrogen, but of nitrogen, chlorine, 257 00:19:29.559 --> 00:19:34.480 and others in the form of vapor. The atomic weights 258 00:19:34.519 --> 00:19:38.440 of these bodies represent also the specific gravities or the 259 00:19:38.480 --> 00:19:42.359 weights of one volume compared with one volume of the standard. 260 00:19:43.039 --> 00:19:47.039 But since it requires two volumes of nitrogen two volumes 261 00:19:47.039 --> 00:19:49.920 of chlorine, et cetera to form the first stage of 262 00:19:49.960 --> 00:19:55.000 oxidation with oxygen, two volumes of nitrogen et cetera, represent 263 00:19:55.119 --> 00:20:00.000 the equivalents of these bodies compared with oxygen. Berzelius consider 264 00:20:00.319 --> 00:20:04.559 that these atoms therefore were united two and two, and 265 00:20:04.680 --> 00:20:10.079 called them the double or compound atoms. A uniform method 266 00:20:10.240 --> 00:20:15.240 of considering compounds dualistically became possible to a still greater 267 00:20:15.359 --> 00:20:20.160 degree in the light of electrical chemical phenomena, and Brasilius 268 00:20:20.160 --> 00:20:25.559 introduced this into chemistry and established it. Davy had inclined 269 00:20:25.599 --> 00:20:29.519 to the assumption that electrical processes and the phenomena of 270 00:20:29.599 --> 00:20:35.559 chemical affinity arose from a common cause. His electrochemical theory 271 00:20:35.839 --> 00:20:39.720 was characterized by the axiom that the small particles of 272 00:20:39.839 --> 00:20:43.839 substances which have an affinity for one another only become 273 00:20:44.000 --> 00:20:50.440 oppositely electrified upon contact. The researches of Brasilius, however, caused 274 00:20:50.480 --> 00:20:54.839 the abandonment of this principle, while otherwise many of Davey's 275 00:20:54.920 --> 00:21:00.359 original ideas were retained. Davy advanced ideas as to the 276 00:21:00.400 --> 00:21:04.079 manner in which he considered chemical and electrical phenomena to 277 00:21:04.119 --> 00:21:07.839 be related, but he never succeeded in producing a theory 278 00:21:07.880 --> 00:21:11.839 which might serve as the basis of a chemical system. 279 00:21:12.240 --> 00:21:16.400 This was accomplished by Brasilius, and therefore his views are 280 00:21:16.480 --> 00:21:20.240 of greater importance in the development of chemistry than those 281 00:21:20.279 --> 00:21:24.200 of Davy are. To quote from A. Leydenberg's lectures on 282 00:21:24.279 --> 00:21:28.279 the History of chemistry. According to Brasilius, it is not 283 00:21:28.319 --> 00:21:32.279 only when two substances are brought into contact that electricity 284 00:21:32.400 --> 00:21:36.039 is generated, but it is a property of matter, and 285 00:21:36.160 --> 00:21:41.359 in every atom two oppositely electrical poles are assumed. These 286 00:21:41.480 --> 00:21:45.680 poles do not, however, contain equal quantities of electricity. The 287 00:21:45.759 --> 00:21:50.440 atoms are unipolar, the electricity of the one pole predominating 288 00:21:50.559 --> 00:21:53.960 over that of the other. And thus every atom and 289 00:21:54.039 --> 00:21:59.720 therefore every element, appears to be either positively or negatively electrical. 290 00:22:00.880 --> 00:22:04.359 In this respect, it is possible to arrange the elementary 291 00:22:04.400 --> 00:22:08.799 substances into a series, so that each member is always 292 00:22:08.920 --> 00:22:14.200 more electronegative than the next. Succeeding one. Oxygen stands at 293 00:22:14.240 --> 00:22:18.920 the top and is absolutely electronegative, while the other substances 294 00:22:18.960 --> 00:22:23.279 are only relatively positive or negative according as they are 295 00:22:23.319 --> 00:22:27.200 compared with elements which come before them or after them 296 00:22:27.359 --> 00:22:32.079 in the electrical series. This series does not constitute a 297 00:22:32.119 --> 00:22:36.480 table of affinities in the Jeffrey Bergmann sense, and it 298 00:22:36.559 --> 00:22:40.920 does not express the affinity of the individual substances. For oxygen, 299 00:22:41.079 --> 00:22:47.519 for example, Brazilius has not forgotten Berthelet's teaching that affinity 300 00:22:47.640 --> 00:22:51.079 is not of a constant character and independent of the 301 00:22:51.160 --> 00:22:56.319 physical conditions, as he supposes this unipolarity to be, and 302 00:22:56.440 --> 00:23:00.000 he is also well aware that oxygen can be removed 303 00:23:00.000 --> 00:23:04.440 moved from metallic oxides by carbon or sulfur, that is 304 00:23:04.480 --> 00:23:09.720 to say, by other electronegative substances. With him, affinity depends 305 00:23:09.759 --> 00:23:13.759 principally upon the intensity of the polarity, for example, upon 306 00:23:13.880 --> 00:23:17.599 the quantity of electricity which is contained in the two poles. 307 00:23:18.759 --> 00:23:22.839 This is variable, however, especially with changes of temperature, and 308 00:23:23.079 --> 00:23:28.039 generally speaking is increased by furnishing more heat, which explained 309 00:23:28.079 --> 00:23:33.519 why certain combinations only occurred at a high temperature. Chemical 310 00:23:33.559 --> 00:23:38.160 combinations of the elements or compounds consisted, according to Brasilius, 311 00:23:38.720 --> 00:23:41.759 in the attraction of the dissimilar poles of the small 312 00:23:41.839 --> 00:23:46.920 particles and in the consequent neutralization of the different electricities. 313 00:23:47.920 --> 00:23:52.759 When positive electricity predominated in the original substance, then an 314 00:23:52.799 --> 00:23:58.759 electro positive compound resulted, and vice versa. If the electricities 315 00:23:58.799 --> 00:24:05.519 neutralized one another, then an electrically indifferent product was the result. Oxygen, 316 00:24:05.680 --> 00:24:10.000 as the most electronegative element, served Brasilious here as the 317 00:24:10.039 --> 00:24:13.559 standard by which to determine the kind of polarity of 318 00:24:13.599 --> 00:24:18.920 the various elements. Those elements which yielded basic compounds with oxygen, 319 00:24:19.319 --> 00:24:23.319 even although only their lowest oxides were basic, were classed 320 00:24:23.319 --> 00:24:29.200 as electropositive, and those whose oxides were acids as electronegative. 321 00:24:30.240 --> 00:24:33.880 Following this principle, he arranged the simple substances in a 322 00:24:34.000 --> 00:24:38.480 series in which oxygen as the first member, was followed 323 00:24:38.519 --> 00:24:42.440 by the other metalloids, while hydrogen formed the bridge between 324 00:24:42.559 --> 00:24:46.519 the latter and the metals, the whole ending with sodium 325 00:24:46.680 --> 00:24:53.240 and potassium. Such conceptions form the substance of his electrochemical theory, 326 00:24:53.759 --> 00:24:58.359 which constituted the basis of the dualistic theory of chemical composition. 327 00:24:59.400 --> 00:25:05.200 Brasilius established it as follows. If the electrochemical views are accurate, 328 00:25:05.640 --> 00:25:09.799 it follows that every chemical combination depends wholly and solely 329 00:25:09.880 --> 00:25:15.160 upon two opposite forces, namely the positive and the negative electricities, 330 00:25:16.039 --> 00:25:19.880 and that every compound must be composed of two parts 331 00:25:20.000 --> 00:25:24.759 united by the effects of their electrochemical reactions. Since there 332 00:25:24.839 --> 00:25:28.720 is not any third force. From this, it follows that 333 00:25:28.799 --> 00:25:33.039 every compound substance, whatever the number of its constituents may be, 334 00:25:33.640 --> 00:25:36.759 can be divided into two parts, of which the one 335 00:25:36.839 --> 00:25:42.599 is positively and the other is negatively electrical. Thus, for example, 336 00:25:42.759 --> 00:25:48.119 sulfate of soda is not composed of sulfur oxygen and sodium, 337 00:25:48.599 --> 00:25:52.319 but of sulfuric acid and soda, each of which can 338 00:25:52.720 --> 00:25:56.839 in turn be separately divided into an electropositive and an 339 00:25:56.880 --> 00:26:02.160 electronegative constituent in the same way. Also, alum cannot be 340 00:26:02.200 --> 00:26:06.359 regarded as immediately composed of its elementary constituents, but is 341 00:26:06.359 --> 00:26:08.759 to be looked upon as the product of the reaction 342 00:26:08.960 --> 00:26:13.400 of sulfate of aluminum as negative element, with sulfate of 343 00:26:13.519 --> 00:26:19.079 potash as positive element. And thus the electrochemical view justifies 344 00:26:19.119 --> 00:26:22.240 what I have said with respect to compound atoms of 345 00:26:22.319 --> 00:26:28.480 the first, second, third, etc. Orders. In the year eighteen nineteen, 346 00:26:28.920 --> 00:26:34.160 when Brazilius contributed a complete exposition of his electrochemical theory, 347 00:26:34.240 --> 00:26:38.839 he was convinced that all acids contained oxygen. In his view, 348 00:26:39.000 --> 00:26:42.039 water assumed in hydrated acids the role of a weak 349 00:26:42.160 --> 00:26:46.799 electropositive constituent, and in metallic hydroxides that of a weak 350 00:26:46.880 --> 00:26:51.640 electronegative one. The hydrates of sulfuric acid and of cupric 351 00:26:51.720 --> 00:27:02.680 oxide therefore receive the formula H two so three CuO two. 352 00:27:03.000 --> 00:27:06.960 The binary conception, which had already been applied by Levosier 353 00:27:07.480 --> 00:27:11.599 to acids and bases, and even by Ruelle to salt, 354 00:27:12.160 --> 00:27:16.519 thus received the strongest support from the electrochemical theory and 355 00:27:16.880 --> 00:27:22.319 was materially developed as a result. Finally, however, the theory 356 00:27:22.400 --> 00:27:26.079 of the oxygen acids based on the tenet established by 357 00:27:26.119 --> 00:27:31.000 Levosia was abandoned by chemists during the second decade of 358 00:27:31.039 --> 00:27:35.319 the nineteenth century as a knowledge of facts in opposition 359 00:27:35.400 --> 00:27:39.839 to it augmented, and at last Brasilius convinced himself of 360 00:27:39.880 --> 00:27:43.759 the existence of acids free from oxygen, at which time 361 00:27:43.880 --> 00:27:48.440 the unadaptable system of dualism began to decline in favor. 362 00:27:49.799 --> 00:27:54.000 It had explained, however, the mysterious chemical force, even though 363 00:27:54.039 --> 00:27:59.119 the identification of chemical affinity with electrical polarity was one 364 00:27:59.240 --> 00:28:03.519 not justified by the facts at hand, and dominated chemistry 365 00:28:03.599 --> 00:28:08.400 for two decades. As a result of the efforts of Brazilius, 366 00:28:08.920 --> 00:28:12.480 chemistry was now in the possession of a comprehensive theory 367 00:28:12.519 --> 00:28:18.000 of chemical reaction, a rational and systematic nomenclature, and a 368 00:28:18.079 --> 00:28:22.960 large quantity of experimental data. He was responsible for a 369 00:28:23.000 --> 00:28:27.480 solid basis in the laws of constant proportions and multiples, 370 00:28:27.519 --> 00:28:30.039 and the table of atomic weights, which he published in 371 00:28:30.079 --> 00:28:35.400 eighteen twenty seven, was remarkably accurate the determinations approaching the 372 00:28:35.440 --> 00:28:40.039 more exact work of the present time. These contributions equipped 373 00:28:40.079 --> 00:28:43.799 chemistry for the period of remarkable extension in the accumulation 374 00:28:43.960 --> 00:28:47.359 of data and in the formulation of theory, which the 375 00:28:47.400 --> 00:28:51.880 past eighty years have witnessed. Mention has been made of 376 00:28:51.920 --> 00:28:55.359 the law of DeLong and Petit and of the law 377 00:28:55.440 --> 00:29:00.400 of Mischelik. The exceptions to the former exhibited by many 378 00:29:00.480 --> 00:29:03.680 of the non metals in a greater or lesser diminuation 379 00:29:03.839 --> 00:29:06.920 of the atomic heats, have only in some measure been 380 00:29:06.960 --> 00:29:10.480 explained in recent years by the proof that the specific 381 00:29:10.559 --> 00:29:15.480 heats of such elements vary greatly with the temperature. In 382 00:29:15.519 --> 00:29:19.240 the case of simple chemical compounds, a relation was soon 383 00:29:19.319 --> 00:29:23.400 found between their specific heats and atomic weights by Newman 384 00:29:23.599 --> 00:29:27.359 in eighteen thirty one, who said, I find that for 385 00:29:27.559 --> 00:29:32.119 compound substances a simple relation exists between the specific heats 386 00:29:32.559 --> 00:29:37.440 and the stoichiometric quantities. And I call storchiometric quantities the 387 00:29:37.480 --> 00:29:40.920 amounts of substances which, as for instance, in the case 388 00:29:40.960 --> 00:29:44.759 of the anhydrous carbonates, contain the same amount of oxygen, 389 00:29:45.279 --> 00:29:48.640 while in the case of sulfur compounds, the amount of 390 00:29:48.680 --> 00:29:53.480 sulfur is the measure of the stoichiometric quantity. For chemically 391 00:29:53.519 --> 00:29:58.240 similar substances, the specific heats are inversely proportional to the 392 00:29:58.279 --> 00:30:02.920 storchiometric quantities, or what comes to the same thing, the 393 00:30:02.960 --> 00:30:08.160 storrecheometric quantities of chemically similar substances have the same heat capacity. 394 00:30:09.000 --> 00:30:12.079 The investigation of the carbonates first led me to the 395 00:30:12.160 --> 00:30:17.519 discovery of this law. Renault, who extended the empirical basis 396 00:30:17.559 --> 00:30:21.039 of the law of constant atomic heat in eighteen forty 397 00:30:21.440 --> 00:30:26.000 while engaged in investigations on the specific heats of compounds 398 00:30:26.039 --> 00:30:30.440 corroborated Newman's results, but it was reserved for copp in 399 00:30:30.480 --> 00:30:34.960 eighteen sixty five to definitely prove that the connection between 400 00:30:35.000 --> 00:30:39.319 the specific heat and the composition of a compound holds 401 00:30:39.319 --> 00:30:43.119