WEBVTT 1 00:00:00.960 --> 00:00:05.320 Section eighteen of the Science History of the Universe, Volume four. 2 00:00:06.200 --> 00:00:10.039 This is a LibriVox recording. All LibriVox recordings are in 3 00:00:10.080 --> 00:00:14.400 the public domain. For more information or to volunteer, please 4 00:00:14.480 --> 00:00:19.600 visit LibriVox dot org. The Science History of the Universe, 5 00:00:19.839 --> 00:00:25.320 Volume four, edited by Francis Rolt Wheeler. Chemistry, Chapter fourteen, 6 00:00:25.960 --> 00:00:32.520 Modern inorganic chemistry. Progress in inorganic chemistry during the modern period, 7 00:00:33.600 --> 00:00:37.759 a rapid growth in inorganic chemistry ensued after the introduction 8 00:00:37.920 --> 00:00:42.479 of the new chemistry by Levoisier. A massive information concerning 9 00:00:42.520 --> 00:00:46.079 the nature of the elements and their compounds was accumulated, 10 00:00:46.479 --> 00:00:50.359 and many new bodies were discovered. However, even now, after 11 00:00:50.439 --> 00:00:54.280 the accurate study of the chemical behavior of mineral substances 12 00:00:54.600 --> 00:00:58.079 by many careful investigators, we are still far from a 13 00:00:58.079 --> 00:01:00.960 definite knowledge of the nature of all the elements and 14 00:01:01.000 --> 00:01:04.200 their compounds, and new bodies are from time to time 15 00:01:04.400 --> 00:01:08.079 added to the extensive series already known. In the case 16 00:01:08.079 --> 00:01:12.120 of the elements, for example, Loisier in his Trey de 17 00:01:12.280 --> 00:01:16.359 Chemi mentioned twenty six while eighty one are at the 18 00:01:16.359 --> 00:01:20.519 present time accepted and endeavor to sketch. The important advantages 19 00:01:20.560 --> 00:01:24.120 in inorganic chemistry since the time of davy and gay 20 00:01:24.239 --> 00:01:28.840 lusac will be made in this chapter. Cadmium was discovered 21 00:01:28.840 --> 00:01:32.400 by Stromyer in eighteen seventeen and about the same time 22 00:01:32.480 --> 00:01:37.239 by Hermann. It was named by Stromeyer Cadmia fornicum or 23 00:01:37.319 --> 00:01:40.640 furnace zinc because it was found in the zinc furnace, 24 00:01:41.040 --> 00:01:45.159 Cadmia being the original name for zinc. In the same year, 25 00:01:45.519 --> 00:01:50.040 Lithium was discovered by Arvedsen in petolite in spotumine. The 26 00:01:50.079 --> 00:01:53.519 medal was first obtained by Bunsen and Matheson in eighteen 27 00:01:53.560 --> 00:01:57.079 fifty five. The name is Greek and means stony, and 28 00:01:57.120 --> 00:01:59.760 the metal was so called because it was then supposed 29 00:01:59.799 --> 00:02:02.439 to be found only in rocks and not in the 30 00:02:02.480 --> 00:02:07.359 plant in animal bodies. Silicon was first isolated in eighteen 31 00:02:07.480 --> 00:02:12.039 ten by Brasilius by fusing together iron, carbon and quartz, 32 00:02:12.439 --> 00:02:15.719 and Woolar showed that it exists in the chrystalline form 33 00:02:15.919 --> 00:02:19.639 as well as in the amorphous state. In eighteen twenty seven, 34 00:02:20.000 --> 00:02:24.680 Wooler isolated aluminum by the action of potassium upon its chloride, 35 00:02:24.919 --> 00:02:28.199 and eighteen years later Saint clair Deville prepared the metal 36 00:02:28.280 --> 00:02:32.039 on a large scale by using sodium while Bunsen effected 37 00:02:32.039 --> 00:02:36.719 its preparation by electrolytic means, aluminium is now prepared in 38 00:02:36.800 --> 00:02:42.199 quantity by the electrolytic decomposition of the oxide Alumina dissolved 39 00:02:42.199 --> 00:02:47.039 in cryolite. Beryllium or glucinum was also obtained by Wooler, 40 00:02:47.479 --> 00:02:51.120 who effected its isolation in eighteen twenty eight by the 41 00:02:51.159 --> 00:02:55.400 action of potassium upon the chloride. Bromine was isolated by 42 00:02:55.439 --> 00:02:58.599 Bollard in eighteen twenty six from the mother liquor of 43 00:02:58.680 --> 00:03:03.039 sea salt, and was further investigated three years later by Lowig. 44 00:03:03.520 --> 00:03:07.240 Along with iodine, which was discovered by Courtois in eighteen 45 00:03:07.319 --> 00:03:11.039 eleven in the ashes of sea plants and chlorine, it 46 00:03:11.159 --> 00:03:15.879 constituted the group of halogen elements of Berzelius, since fluorine 47 00:03:15.960 --> 00:03:19.759 was then unknown. The latter was first isolated in eighteen 48 00:03:19.800 --> 00:03:23.960 eighty six by Moi Sau by the electrolysis of hydrogen 49 00:03:24.039 --> 00:03:29.120 fluoride in the presence of potassium fluoride. Tellurium, which had 50 00:03:29.159 --> 00:03:32.639 been discovered by Mueller van Reckenstein in seventeen eighty two, 51 00:03:33.360 --> 00:03:38.039 was thoroughly investigated by Berzelius, who discovered an element chemically 52 00:03:38.120 --> 00:03:43.560 analogous to it selenium in eighteen seventeen. The isolation of 53 00:03:43.599 --> 00:03:47.639 the metals comprising the serrium and yttrium groups has presented 54 00:03:47.719 --> 00:03:52.319 numerous difficulties. Although the discovery of yttria, impure it is 55 00:03:52.400 --> 00:03:56.520 true from admixture with other earths, was accomplished by Godolin 56 00:03:56.719 --> 00:04:00.719 in seventeen ninety four, and investigators have busy themselves with 57 00:04:00.759 --> 00:04:04.039 the question. The chemistry of the serium metals is not 58 00:04:04.080 --> 00:04:08.639 even yet completely elucidated, and may possibly remain unsolved for 59 00:04:08.759 --> 00:04:13.360 considerable time to come. After claw Proth and Berselius had 60 00:04:13.439 --> 00:04:18.240 independently prepared serrium sesqua oxide from serite, and the latter 61 00:04:18.279 --> 00:04:22.120 had identified this as the oxide of a metal, Mozander 62 00:04:22.160 --> 00:04:26.160 discovered two new oxides in crude yttria, the metals of 63 00:04:26.199 --> 00:04:31.399 which lanthanum eighteen thirty four and didium eighteen forty one 64 00:04:31.759 --> 00:04:36.279 he isolated. Two years later, eighteen forty three, he added 65 00:04:36.319 --> 00:04:40.639 to these two others erbium and terbium, whose existence in 66 00:04:40.759 --> 00:04:44.680 nature is not yet, however definitely settled. In spite of 67 00:04:44.680 --> 00:04:47.639 the admirable work which has been done on the subject. 68 00:04:48.199 --> 00:04:51.839 This has given us a better knowledge of yttrium, while yttria, 69 00:04:51.920 --> 00:04:55.399 which was formerly held to be a homogeneous substance has 70 00:04:55.480 --> 00:04:58.680 proved itself a mixture of the oxides of various metals, 71 00:04:58.920 --> 00:05:02.720 of which, however, only one or two has yet been isolated, 72 00:05:02.959 --> 00:05:06.759 for example, the discovery of scandium by Nilsen and Cleeve 73 00:05:06.920 --> 00:05:11.800 in eighteen seventy nine and terbium by Mariak. The most 74 00:05:11.800 --> 00:05:14.720 recent additions to the knowledge of chemistry of this group 75 00:05:14.759 --> 00:05:24.600 of elements and their compounds have been made by Wellsbach, Drosbach, Cruz, Winkler, Crooks, Brauner, Baskerville, Urbane, 76 00:05:24.680 --> 00:05:30.920 and others. Wellsbock separated didium into praso and neoddium. An 77 00:05:30.959 --> 00:05:34.759 analytical method has been elaborated for the separation of the 78 00:05:34.839 --> 00:05:40.199 various constituents of serrium, terbium, and thorium earths, which has 79 00:05:40.279 --> 00:05:43.959 been of help in the manufacture of mantles for incandescent 80 00:05:44.040 --> 00:05:48.959 light burners. Quite recently, Urbane has separated etbium into two 81 00:05:49.040 --> 00:05:55.360 other elements, neo eterbium and lucium. In spectrum analysis, chemistry 82 00:05:55.399 --> 00:06:00.000 now possesses an exceedingly valuable instrument for investigating rare mentas 83 00:06:00.319 --> 00:06:03.120 and earths, and its use in the last five decades 84 00:06:03.279 --> 00:06:07.439 has been extensive. Spectrum analysis has grown out of some 85 00:06:07.480 --> 00:06:13.839 apparently insignificant and disconnected observations made by Margrov, Shiel, Herschel 86 00:06:13.920 --> 00:06:17.480 and others upon the light emitted by flames colored by 87 00:06:17.519 --> 00:06:21.639 certain salts. The spectra of such flames were investigated by 88 00:06:21.720 --> 00:06:27.480 various scientists, among whom Talbot, Miller, Altar, and Swann deserved 89 00:06:27.519 --> 00:06:30.959 first mentioned. But it was only after Kerkhoff in eighteen 90 00:06:31.040 --> 00:06:35.360 sixty proved the definite statement that every glowing vapor emits 91 00:06:35.439 --> 00:06:39.360 rays of the same degree of refrangibility that it absorbs 92 00:06:39.839 --> 00:06:43.759 that spectrum analysis became developed by Bunsen and himself into 93 00:06:43.800 --> 00:06:47.240 one of the great branches of our science. Its importance 94 00:06:47.279 --> 00:06:51.680 for analytical chemistry, especially in the discovery of new elements, 95 00:06:51.800 --> 00:06:54.639 is almost beyond mention, and it opened up a new 96 00:06:54.680 --> 00:07:00.399 era in chemistry. Roscoe once said, the spectroscope, next to 97 00:07:00.439 --> 00:07:03.800 the balance, is the most useful and important instrument which 98 00:07:03.839 --> 00:07:08.399 the chemist possesses. Crooks has remarked, if I name the 99 00:07:08.439 --> 00:07:12.199 spectroscope as the most important scientific invention of the latter 100 00:07:12.240 --> 00:07:14.720 half of this century, I shall not fear to be 101 00:07:14.839 --> 00:07:19.800 accused of exaggeration. The very importance of the subject prevents 102 00:07:19.800 --> 00:07:23.279 an entrance into any long discussion of it. Here it 103 00:07:23.319 --> 00:07:26.120 has come to form a distinct branch of chemical science. 104 00:07:26.560 --> 00:07:29.040 In the hands of men like Bunsen and Crooks. It 105 00:07:29.120 --> 00:07:32.319 has explored the recesses of the rocks for minute traces 106 00:07:32.319 --> 00:07:36.560 of hidden treasures, while with it workers like Miller, Huggins 107 00:07:36.560 --> 00:07:40.319 and Locheer have fathomed the abysses of space and determined 108 00:07:40.319 --> 00:07:44.360 the constitution of the stars. Among the elements discovered by 109 00:07:44.399 --> 00:07:48.160 the use of the spectroscope were rubidium and caesium in 110 00:07:48.240 --> 00:07:52.920 lepidolite and in the Durkheim mineral water by Bunsen and Kerkhoff, 111 00:07:53.519 --> 00:07:57.160 Indian by Reich and Richter in eighteen sixty three as 112 00:07:57.199 --> 00:08:01.959 a constituent of Freyburg, zinc, blend, gallium in eighteen seventy 113 00:08:02.000 --> 00:08:06.519 five by Les Coc des Bois bas Drawn, and thallium 114 00:08:06.600 --> 00:08:10.079 by Crooks in eighteen sixty one. The chemical nature of 115 00:08:10.120 --> 00:08:13.079 the last mentioned metal was established by Lamy in the 116 00:08:13.120 --> 00:08:16.600 same year. The knowledge of the metals discovered in the 117 00:08:16.639 --> 00:08:21.600 preceding era was greatly enlarged by investigations conducted during this period. 118 00:08:22.000 --> 00:08:27.319 The analogues of nitrogen, phosphorus, arsenic, antimony, and bismuth were 119 00:08:27.360 --> 00:08:31.480 carefully examined, and the atomic weight which Berselius determined for 120 00:08:31.560 --> 00:08:35.360 phosphorus was confirmed by Duma, while his atomic weight for 121 00:08:35.480 --> 00:08:39.399 arsenic was corroborated by Pelus and Duma. The metals of 122 00:08:39.440 --> 00:08:44.879 the alkaline earths barium, strontium, calcium, and magnesium, which were 123 00:08:44.960 --> 00:08:50.200 isolated by Davy, were investigated by Berselius, Mariac and Duma, 124 00:08:50.600 --> 00:08:55.480 who determined their atomic weights. Recently, Winkler found that magnesium 125 00:08:55.679 --> 00:08:59.799 is an excellent reducing agent for metallic oxides. Cobalt and 126 00:08:59.840 --> 00:09:02.480 n Nickel have been the subject of researches of an 127 00:09:02.480 --> 00:09:06.480 important nature, mainly because of the remarkable compounds they form, 128 00:09:06.879 --> 00:09:12.720 for example, nickel tetracarbonyl and the ammonio cobolic compounds. Nickel 129 00:09:12.840 --> 00:09:16.559 is now extensively used in metallurgy, especially in the production 130 00:09:16.759 --> 00:09:21.159 of nickel steel. The rarer metals have of course received 131 00:09:21.200 --> 00:09:25.720 considerable attention. Uranium, which was discovered by claw Proth in 132 00:09:25.799 --> 00:09:30.320 seventeen ninety eight, was investigated further by Pelago, Roscoe and 133 00:09:30.440 --> 00:09:36.519 lately by Zimmermann. Molybdenum and tungsten, isolated respectively by Helm 134 00:09:36.600 --> 00:09:40.000 and del Huriar have become better known, and the acids 135 00:09:40.039 --> 00:09:45.320 and the complicated salts of these have been studied by Scribbler, Mariac, Friedheim, 136 00:09:45.440 --> 00:09:50.759 and Gibbs. Uranium and particularly tungsten and molybdenum, are now 137 00:09:50.879 --> 00:09:56.039 employed extensively as steel hardening materials. Uranium compounds are also 138 00:09:56.200 --> 00:10:01.960 used in dyeing and ceramics. Titanium, zirconium, and thorium have 139 00:10:02.159 --> 00:10:06.320 now become in the form of various compounds, particularly the 140 00:10:06.360 --> 00:10:11.559 oxide of practical importance. Thorium was discovered by Berselius in 141 00:10:11.639 --> 00:10:15.840 eighteen twenty eight. Its oxide Thoria, is applied in the 142 00:10:15.879 --> 00:10:20.480 manufacture of Wellsbock gas mantles, which consists essentially of a 143 00:10:20.519 --> 00:10:24.919 web of ninety nine percent thoria and one percent serium oxide. 144 00:10:25.360 --> 00:10:29.120 Titanium is employed for the manufacture of special alloys, and 145 00:10:29.240 --> 00:10:33.639 zirconium Azirconia is made use of both in gas and 146 00:10:33.679 --> 00:10:39.320 electric illumination. Germanium, an element which resembles these in some respects, 147 00:10:39.799 --> 00:10:42.720 was discovered by Winkler in eighteen eighty six in a 148 00:10:42.759 --> 00:10:47.480 Freiberg silver ore. The element Vanandium, which was discovered by 149 00:10:47.519 --> 00:10:51.080 del Rio in eighteen oh one, was isolated by Roscoe 150 00:10:51.240 --> 00:10:55.960 in eighteen sixty seven. He also investigated its compounds, carefully 151 00:10:56.000 --> 00:11:00.480 determining its different stages of combination with oxygen and cline. 152 00:11:01.039 --> 00:11:04.679 This metal, which is widely distributed, is utilized in the 153 00:11:04.679 --> 00:11:08.879 production of sheet and toul steel and armor plates. Tantalum, 154 00:11:08.960 --> 00:11:13.360 a related metal, which along with columbium or neobium, was 155 00:11:13.399 --> 00:11:18.279 examined exhaustively by Blomstrand and Mariac, is used in alloys 156 00:11:18.320 --> 00:11:21.559 to make small springs and anvils, and in the metallic 157 00:11:21.600 --> 00:11:26.519 form to make special incandescent electric light filaments. The metals 158 00:11:26.519 --> 00:11:31.759 of the platinum group platinum, palladium wolston in eighteen O three, 159 00:11:32.120 --> 00:11:37.360 rhodium wolston in eighteen o four, iridium tenant in eighteen 160 00:11:37.360 --> 00:11:42.159 O three, osmium tenant in eighteen O three, and ruthenium 161 00:11:42.480 --> 00:11:46.320 klaus in eighteen forty four have been given careful consideration 162 00:11:46.399 --> 00:11:50.919 by chemists. Platinum is used extensively in making chemical apparatus, 163 00:11:51.320 --> 00:11:55.960 especially crucibles and stills, and osmium and iridium have recently 164 00:11:56.000 --> 00:12:00.919 come into use as filaments for incandescent lamps. About fifteen 165 00:12:01.000 --> 00:12:04.200 years ago, the number of the chemical elements was enlarged 166 00:12:04.279 --> 00:12:08.559 by two gases of great theoretical interest, argon and helium. 167 00:12:09.120 --> 00:12:13.080 As early as seventeen eighty five, Cavendish had noticed that 168 00:12:13.159 --> 00:12:16.960 a residue of about zero point six percent remained when 169 00:12:16.960 --> 00:12:20.399 the nitrogen and oxygen were removed from air, and in 170 00:12:20.480 --> 00:12:24.720 eighteen ninety four Raleigh discovered that nitrogen from the atmosphere 171 00:12:25.120 --> 00:12:29.200 was zero point five percent heavier than nitrogen prepared chemically. 172 00:12:29.919 --> 00:12:33.600 Raleigh and Ramsey then prepared large quantities of this atmospheric 173 00:12:33.679 --> 00:12:37.039 residue and found it to be a gas different from nitrogen. 174 00:12:37.240 --> 00:12:40.840 They called it argone, from the Greek argos for lazy. 175 00:12:41.799 --> 00:12:45.200 Helium was discovered by Ramsey in eighteen ninety five in 176 00:12:45.240 --> 00:12:48.919 the mineral clevite. It had already been found to exist 177 00:12:49.000 --> 00:12:52.200 in the chromosphere of the Sun by Jansen in eighteen 178 00:12:52.240 --> 00:12:56.720 sixty eight, and his observations were confirmed by Franklin and Lockier. 179 00:12:57.320 --> 00:13:02.080 Helium primarily obtained by heating clean with sulfuric acid, and 180 00:13:02.159 --> 00:13:06.360 since found in small quantity, often together with argon found 181 00:13:06.440 --> 00:13:10.720 in the mineral's uraniite, malacone, et cetera, as well as 182 00:13:10.720 --> 00:13:14.320 in the gases from some mineral water springs, is like argon, 183 00:13:14.679 --> 00:13:18.919 inert and indifferent. Up to now, in spite of persistent effort, 184 00:13:19.360 --> 00:13:22.960 no compound of either argone or helium has been prepared 185 00:13:23.480 --> 00:13:27.600 and Further, Although many diffusion experiments with both gases have 186 00:13:27.720 --> 00:13:30.679 been carried out with the object of seeing whether they 187 00:13:30.720 --> 00:13:35.120 were really elementary, the densities of both have remained unaltered. 188 00:13:35.320 --> 00:13:39.120 For example, it has been found impossible to subdivide them 189 00:13:39.399 --> 00:13:43.120 by diffusion into two or more components. From the ratio 190 00:13:43.240 --> 00:13:46.759 of the specific heats at constant volume and constant pressure, 191 00:13:47.200 --> 00:13:50.519 it follows that the molecule and atom are identical in 192 00:13:50.600 --> 00:13:55.159 both argon and helium, for example, that the gases are monatomic, 193 00:13:55.559 --> 00:13:58.759 and this applies also to the more recently discovered gases 194 00:13:58.840 --> 00:14:04.080 of the airton neon and xenon. These were separated from 195 00:14:04.120 --> 00:14:07.840 liquid air in eighteen ninety eight by Ramsey and Traverse. 196 00:14:08.200 --> 00:14:11.000 The atomic weights of these gases and the proportions in 197 00:14:11.039 --> 00:14:14.200 which they are present in the air are as follows. 198 00:14:14.679 --> 00:14:18.960 Helium atomic weight four one part by volume in air 199 00:14:19.440 --> 00:14:24.320 two thousand, four hundred and fifty volumes. Neon atomic weight 200 00:14:24.559 --> 00:14:29.840 twenty one part by volume in air, eight hundred eight volumes. 201 00:14:30.559 --> 00:14:34.799 Rgon atomic weight thirty nine point nine one part by 202 00:14:34.879 --> 00:14:39.840 volume in air, one hundred and five volumes. Krypton atomic 203 00:14:39.919 --> 00:14:43.240 weight eighty one point eight one part by volume in 204 00:14:43.320 --> 00:14:48.559 air seven hundred and forty six thousand volumes, xenon atomic 205 00:14:48.600 --> 00:14:52.080 weight one hundred and twenty eight one part by volume 206 00:14:52.159 --> 00:14:56.440 in air three million, eight hundred and forty six thousand volumes. 207 00:14:57.320 --> 00:15:00.519 Since the interest attached to these gases has been recently 208 00:15:00.559 --> 00:15:04.679 augmented by the discovery of Ramsey and Saudi that radium 209 00:15:04.720 --> 00:15:09.320 emanation eventually changes, at least in part into helium, and 210 00:15:09.360 --> 00:15:12.720 since Ramsey has shown that when the radium emanation decays 211 00:15:12.879 --> 00:15:16.279 in the presence of water, neon is produced, and that 212 00:15:16.480 --> 00:15:19.320 argone results when the decay takes place in the presence 213 00:15:19.360 --> 00:15:23.799 of water containing a copper salt in solution. The radioactive 214 00:15:23.799 --> 00:15:28.840 elements may be conveniently referred to here. Nribeckerrel found in 215 00:15:28.919 --> 00:15:34.399 eighteen ninety six that compounds of uranium spontaneously and continuously 216 00:15:34.519 --> 00:15:39.159 emit some radiation, which, among other properties, has that of 217 00:15:39.240 --> 00:15:43.759 making air a conductor of electricity. This effect, the quantity 218 00:15:43.879 --> 00:15:47.480 of which can be determined with great accuracy, was used 219 00:15:47.480 --> 00:15:51.159 by Madame Sklodowska Curie to measure the amount of radiation 220 00:15:51.279 --> 00:15:55.720 produced by various compounds of uranium and of thorium, which 221 00:15:55.799 --> 00:15:58.559 latter had been found by Schmidt to emit the same 222 00:15:58.679 --> 00:16:02.559 kind of radiation. She subsequently tested a large number of 223 00:16:02.639 --> 00:16:05.799 rocks and minerals and found that certain minerals which contain 224 00:16:06.000 --> 00:16:11.639 uranium and thorium, for example, pitchblend, oxide of uranium, calcolite, 225 00:16:11.919 --> 00:16:16.919 double phosphate of copper and uranium, possess radioactivity much greater 226 00:16:17.000 --> 00:16:20.600 than that theoretically due to the amount of uranium present. 227 00:16:21.240 --> 00:16:27.279 Madame Curie therefore inferred that it appeared probable that if pitchblend, calcolite, 228 00:16:27.360 --> 00:16:31.200 et cetera possessed so great a degree of activity, these 229 00:16:31.240 --> 00:16:35.600 substances contain a small quantity of a strongly radioactive body, 230 00:16:36.120 --> 00:16:40.360 differing from uranium and thorium and the simple bodies actually known. 231 00:16:40.879 --> 00:16:43.440 I thought that if this were indeed the case, I 232 00:16:43.559 --> 00:16:46.279 might hope to extract this substance from the ore by 233 00:16:46.320 --> 00:16:52.559 the ordinary methods of chemical analysis. The investigation was consequently pursued, 234 00:16:52.919 --> 00:16:55.960 and with the assistance of her husband, Pierre Curie and 235 00:16:56.000 --> 00:17:00.159 Gustav Beamont, Madame Curie commenced the la warious treatment of 236 00:17:00.200 --> 00:17:04.640 the residue remaining after the extraction of the uranium from pitchblend, 237 00:17:05.119 --> 00:17:07.640 a large quantity of which had been placed at her 238 00:17:07.680 --> 00:17:11.799 disposal by the Austrian government and finally separated the salts 239 00:17:11.839 --> 00:17:16.319 of radium in eighteen ninety eight. While endeavoring to isolate radium, 240 00:17:16.559 --> 00:17:22.000 Madame Curie discovered polonium, and other investigators De Bierney, Gazelle, 241 00:17:22.160 --> 00:17:26.519 mark Wald, and Hoffmann have given the names of actinium, imanium, 242 00:17:26.920 --> 00:17:31.720 radio tellurium, and radio led to similar substances, the two 243 00:17:31.839 --> 00:17:35.680 last being possible products of the spontaneous change in radium. 244 00:17:36.039 --> 00:17:39.039 Among those who have worked with success upon the problem 245 00:17:39.200 --> 00:17:44.920 of radioactivity, Elster and ghettl Rutherford, Saudi, and Ramsay may 246 00:17:44.920 --> 00:17:49.440 be mentioned here. Radium maintains a temperature one or more 247 00:17:49.480 --> 00:17:52.960 degrees above that of the atmosphere, injures the eyes and 248 00:17:53.039 --> 00:17:57.160 disorganizes the flesh when kept long in contact with it. 249 00:17:57.160 --> 00:18:00.720 Its peculiar properties have been explained in various ways. The 250 00:18:00.720 --> 00:18:04.599 most plausible suggestion is that atoms of high atomic weight 251 00:18:04.920 --> 00:18:09.200 slowly disintegrate into ultimate corpuscles or particles, and that this 252 00:18:09.319 --> 00:18:14.160 decomposition is attendant with the development of great energy. The 253 00:18:14.200 --> 00:18:18.039 successive disintegration of the radium atom, as exemplified by the 254 00:18:18.119 --> 00:18:22.039 disintegration of products, is shown in the following table, which 255 00:18:22.119 --> 00:18:26.640 represents according to Ernst Rutherford. The complete radium series as 256 00:18:26.680 --> 00:18:33.960 at present known. Radium radiation emitted alpha particles period two 257 00:18:34.079 --> 00:18:37.960 thousand years. Range of alpha particles in air at normal 258 00:18:38.000 --> 00:18:44.240 pressure three point five centimeters. Radium emanation radiation emitted alpha 259 00:18:44.240 --> 00:18:49.000 particles period thirty eight days. Range of alpha particles in 260 00:18:49.079 --> 00:18:53.839 air at normal pressure four point three centimeters. Radium A 261 00:18:54.759 --> 00:18:59.960 radiation emitted alpha particles period three minutes. Range of ALCA 262 00:19:00.200 --> 00:19:04.000 particles in air at normal pressure four point eight centimeters. 263 00:19:04.839 --> 00:19:10.880 Radium B radiation emitted beta particles period twenty six minutes. 264 00:19:11.680 --> 00:19:17.599 Radium C radiation emitted alpha and beta particles, gamma rays 265 00:19:17.920 --> 00:19:22.359 period nineteen minutes. Range of alpha particles in air at 266 00:19:22.359 --> 00:19:29.079 normal pressure seven point zero six centimeters. Radium D radiation 267 00:19:29.240 --> 00:19:36.920 emitted unknown period forty years. Radium E radiation emitted unknown 268 00:19:37.319 --> 00:19:44.839 period six days, Radium F radiation emitted beta particles period 269 00:19:45.119 --> 00:19:51.480 four point five days. Radium G radiation emitted alpha particles 270 00:19:52.039 --> 00:19:55.960 period one hundred and forty days. Range of alpha particles 271 00:19:55.960 --> 00:19:59.440 in air at normal pressure three point eight six centimeters. 272 00:20:00.720 --> 00:20:03.599 It appears that uranium is the source of radium, and 273 00:20:03.680 --> 00:20:07.920 Boltwood has recently announced the immediate parent of radium ionium. 274 00:20:08.599 --> 00:20:13.319 Radium represents barium chemically, and according to Madame Curi and Thorpe, 275 00:20:13.480 --> 00:20:16.160 it has an atomic weight of two hundred and twenty 276 00:20:16.279 --> 00:20:20.759 six point five. Several observers have demonstrated that it possesses 277 00:20:20.799 --> 00:20:27.079 a characteristic spectrum, and consequently, notwithstanding its disintegration and peculiar conduct, 278 00:20:27.559 --> 00:20:31.000 radium is regarded as a chemical element, owing to an 279 00:20:31.039 --> 00:20:34.640 affidation among chemists to recognize a body as a chemical 280 00:20:34.680 --> 00:20:39.240 element when under proper conditions it possesses a definite atomic 281 00:20:39.279 --> 00:20:43.640 weight and exhibits a spectrum containing characteristic and novel lines. 282 00:20:44.559 --> 00:20:48.480 In eighteen twenty three, Miskerlik discovered the existence of sulfur 283 00:20:48.640 --> 00:20:53.000 in two different chrystaline varieties, rhombic and oblique, and a 284 00:20:53.000 --> 00:20:57.839 third variety of plastic form was also known. Frankenheim learned 285 00:20:57.839 --> 00:21:02.359 that by heating and cooling, these varieties could, at definite temperatures, 286 00:21:02.720 --> 00:21:06.440 be converted into one another, and in describing these phenomena, 287 00:21:06.680 --> 00:21:11.359 the term isomerism was employed, to which, however, bersellia Is 288 00:21:11.400 --> 00:21:15.160 published an objection in eighteen forty one, to quote from 289 00:21:15.200 --> 00:21:20.160 his jahresbirict for that year, I feel compelled to call 290 00:21:20.200 --> 00:21:23.640 attention to the fact that the word isomerism, which is 291 00:21:23.680 --> 00:21:26.799 applied to different substances composed of an equal number of 292 00:21:26.839 --> 00:21:30.279 atoms of the same elements, is not compatible with the 293 00:21:30.359 --> 00:21:33.480 view as to the cause of the different properties exhibited 294 00:21:33.680 --> 00:21:37.960 by the various modifications of sulfur, carbon, silicon, et cetera. 295 00:21:38.759 --> 00:21:41.640 While the term still lends itself to the expression of 296 00:21:41.680 --> 00:21:45.680 the relation between ethyl formate and methylacetate, it is no 297 00:21:45.720 --> 00:21:49.160 longer suitable in the case of simple substances which assume 298 00:21:49.240 --> 00:21:52.759 different properties, and it might be desirable to substitute for 299 00:21:52.799 --> 00:21:58.359 a better chosen term, for example allotropy or allotropic modifications. 300 00:21:58.799 --> 00:22:01.240 In accordance with these views use there can be more 301 00:22:01.279 --> 00:22:05.079 than one cause for that which we call isomerism, namely 302 00:22:05.720 --> 00:22:09.799 one allotropy, in which case the difference between the sulfides 303 00:22:09.839 --> 00:22:12.279 of iron is due to the fact that they contain 304 00:22:12.559 --> 00:22:17.480 different modifications of sulfur. Two differences in the relative position 305 00:22:17.559 --> 00:22:20.039 of the atoms in the compound of which the two 306 00:22:20.160 --> 00:22:24.079 kinds of ether, ethyl formate and methyl lacetate are so 307 00:22:24.200 --> 00:22:28.279 striking a proof three a combination of one and two. 308 00:22:30.039 --> 00:22:33.079 Since then, the term allotropy has been in constant use, 309 00:22:33.319 --> 00:22:37.759 and numerous allotropic phenomena have been observed, particularly among the 310 00:22:37.799 --> 00:22:41.880 non metals. The allotropism of carbon was the first observed 311 00:22:41.920 --> 00:22:46.920 example seventeen seventy three, and its modifications exhibit marked points 312 00:22:46.920 --> 00:22:52.880 of difference. For instance, comparing diamond and graphite. Carbon diamond 313 00:22:53.359 --> 00:23:00.839 crystallographic system, cubic optical properties, colorless, transparent, high refractive index 314 00:23:01.359 --> 00:23:06.039 MEW equals two point four one seven, chemical and physical properties. 315 00:23:06.480 --> 00:23:11.119 Non conductor of heat and electricity not attacked by oxidizing agents. 316 00:23:11.519 --> 00:23:15.599 Ignition temperature seven hundred and sixty degrees to eight hundred 317 00:23:15.599 --> 00:23:20.160 and seventy five degrees, specific gravity three point five two 318 00:23:20.400 --> 00:23:31.279 hardness ten. Carbon graphite crystallographic system hexagonal or oblique optical properties, opaque, 319 00:23:31.680 --> 00:23:36.000 chemical and physical properties. Good conductor of heat and electricity 320 00:23:36.200 --> 00:23:41.039 oxidized to gryphytic acid. Ignition temperature five hundred and seventy 321 00:23:41.039 --> 00:23:45.279 five degrees and above, specific gravity two point twenty five 322 00:23:45.640 --> 00:23:53.119 hardness one. When amapherous carbon, coal, peat, lampblack, et cetera, 323 00:23:53.519 --> 00:23:57.279 and diamond are heated, they pass into the graphitic variety, 324 00:23:57.759 --> 00:24:00.759 and graphite is now produced in large amounts by heating 325 00:24:00.799 --> 00:24:05.359 carbon to a high temperature four thousand degrees celsius by 326 00:24:05.400 --> 00:24:10.039 an alternating electric current. En Remoisson eighteen fifty two to 327 00:24:10.160 --> 00:24:14.519 nineteen o seven, an eminent French chemist, succeeded in preparing 328 00:24:14.559 --> 00:24:18.920 synthetic diamonds by dissolving pure sugar charcoal in molten pure 329 00:24:18.960 --> 00:24:22.480 iron and suddenly cooling the mass by plunging it into water. 330 00:24:22.920 --> 00:24:27.119 And three English chemists, Sir F. A. Abel, W. H. 331 00:24:27.200 --> 00:24:31.279 Noble and Sir William Crooks, obtained diamonds by exploding some 332 00:24:31.359 --> 00:24:34.799 of the high explosives and steel bombs. The liquid carbon 333 00:24:34.839 --> 00:24:39.400 produced crystallizing as it cooled. However, no diamonds have thus 334 00:24:39.400 --> 00:24:44.000 far been produced of commercial size or amount. The most peculiar, 335 00:24:44.160 --> 00:24:48.079 as well as noteworthy example of allotropism is afforded by 336 00:24:48.079 --> 00:24:52.160 the conversion of oxygen into ozone. Ozone was first noticed 337 00:24:52.200 --> 00:24:56.119 by Van Marum in seventeen eighty five in electrified air. 338 00:24:56.599 --> 00:25:00.319 In eighteen forty, C. F. Schauenbein called attention again to 339 00:25:00.400 --> 00:25:04.480 this substance, discovering its oxidizing action, and showed that it 340 00:25:04.599 --> 00:25:07.640 was produced in the electrolysis of water and in the 341 00:25:07.680 --> 00:25:11.079 slow combustion of phosphorus and sulfur. He gave it the 342 00:25:11.160 --> 00:25:15.839 name ozone, which means a smell The investigations of Mariac 343 00:25:16.200 --> 00:25:21.119 des la Revee, Becquerel, Tait, Fremi, Andrews and Brodie have 344 00:25:21.279 --> 00:25:25.119 proved it to be modified oxygen. Its density was determined 345 00:25:25.119 --> 00:25:29.160 by Suret in eighteen sixty. The latter and before him, 346 00:25:29.279 --> 00:25:34.240 Andrews proved that the ozone molecule contains three atoms of oxygen, 347 00:25:34.759 --> 00:25:37.359 while a molecule of the latter is made up of 348 00:25:37.400 --> 00:25:41.640 two atoms. Ozone is now used in the sterilization of water. 349 00:25:42.559 --> 00:25:47.240 Among other allotropic modifications, those of selenium and phosphorus are 350 00:25:47.319 --> 00:25:52.279 of interest. Berzelius investigated the allotropes of selenium, and those 351 00:25:52.319 --> 00:25:57.039 of phosphorus were studied by Berselius, Stroder, Hittorf and schend 352 00:25:57.680 --> 00:26:00.880 Stroder discovered the red variety in anais eighteen forty five, 353 00:26:01.279 --> 00:26:03.759 and Hittor found that it could be transformed into a 354 00:26:03.799 --> 00:26:09.039 metallic modification. Several additional allotropes of sulfur have been discovered 355 00:26:09.079 --> 00:26:11.799 in late years, and the fact that many metals can 356 00:26:11.880 --> 00:26:16.440 exist in allotropic forms has been clearly demonstrated, for example, 357 00:26:16.759 --> 00:26:21.319 colloidal gold, silver, platinum, and mercury. The list of the 358 00:26:21.359 --> 00:26:24.599 compounds of the elements was greatly extended from the time 359 00:26:24.640 --> 00:26:28.880 of Laoissier. Particularly with the discovery of new acids and 360 00:26:28.960 --> 00:26:32.680 the growing knowledge of the different basity of the various acids, 361 00:26:33.000 --> 00:26:36.319 it is important to mention some of the discoveries of moment. 362 00:26:37.039 --> 00:26:40.720 In eighteen eighteen, one of the most interesting of inorganic 363 00:26:40.799 --> 00:26:44.640 compounds was discovered by Thienard. He proved that water is 364 00:26:44.680 --> 00:26:48.839 not the sole oxide of hydrogen, but that another peroxide 365 00:26:48.880 --> 00:26:53.400 of hydrogen, but which he termed oxygenated water, may be prepared. 366 00:26:54.039 --> 00:26:57.759 This compound plays a prominent role in many processes of nature, 367 00:26:58.039 --> 00:27:01.920 and is now prepared in quantities by treating barium dioxide 368 00:27:02.119 --> 00:27:07.319 with sulfuric acid for disinfecting and bleaching purposes. The list 369 00:27:07.359 --> 00:27:10.680 of the halogen acids was completed prior to eighteen twenty. 370 00:27:11.440 --> 00:27:16.400 Gay Lusac and Bollard study hydriotic and hydrobromic acids. The 371 00:27:16.480 --> 00:27:22.720 former Davi and Faraday investigated hydrochloric acid, while Thinard, gay Lusac, 372 00:27:22.759 --> 00:27:27.880 and Bresalius contributed greatly to an intimate knowledge of hydrofluoric acid. 373 00:27:28.359 --> 00:27:32.400 In eighteen sixty nine, Gore and Nicholas continued the investigation 374 00:27:33.079 --> 00:27:36.960 of anhydrous hydrofluoric acid, and the latter lost his life 375 00:27:36.960 --> 00:27:41.200 through its action, Gore and Fermi established its composition, but 376 00:27:41.440 --> 00:27:45.240 as before mentioned, the element fluorine was not isolated until 377 00:27:45.279 --> 00:27:49.880 eighteen eighty six. The oxygen compounds of chlorine, iodine, and 378 00:27:49.920 --> 00:27:53.079 bromine have been given much attention since the commencement of 379 00:27:53.119 --> 00:27:56.839 the nineteenth century. The work of gay Lusac on chloric acid, 380 00:27:57.359 --> 00:28:02.519 Ballard on hypochlorous acid, on chlorous acid, and Davy and 381 00:28:02.559 --> 00:28:07.240 Stadion on chlorine peroxide was exceedingly valuable and led to 382 00:28:07.319 --> 00:28:11.759 researches which firmly established the composition of these bodies. The 383 00:28:11.799 --> 00:28:16.240 oxygen compounds of iodine receive careful attention in the hands 384 00:28:16.279 --> 00:28:20.039 of Davy and Magnus, and the latter discovered iodic acid, 385 00:28:20.240 --> 00:28:25.279 the principal compound of that halogen. Following gay lusax discovery 386 00:28:25.519 --> 00:28:30.359 of hyposulfurrous acid in eighteen thirteen and dithionic acid in 387 00:28:30.440 --> 00:28:33.960 eighteen nineteen, little attention was given to the compounds of 388 00:28:34.000 --> 00:28:38.200 sulfur and oxygen until the fourth decade, when the thio acids, 389 00:28:38.400 --> 00:28:41.599 which contain more sulfur and are more closely related to 390 00:28:41.640 --> 00:28:46.839 sulfuric acid, were recognized. More recently, the early known oxides 391 00:28:46.880 --> 00:28:51.799 of sulfur, sulfur dioxide and sulfur trioxide have received several 392 00:28:51.839 --> 00:28:57.400 additions in sulfur cesqua oxide, sulfur tetroxide, and sulfur heptoxide. 393 00:28:57.720 --> 00:29:01.799 Sulfuric acid, the most important of all chemicals, is used 394 00:29:01.799 --> 00:29:05.799 in enormous quantities in the industries, and its manufacture has 395 00:29:05.839 --> 00:29:09.359 been immensely developed. Over two million tons were used in 396 00:29:09.400 --> 00:29:13.480 the United States in nineteen o eight. The very poisonous 397 00:29:13.519 --> 00:29:19.359 compounds of hydrogen with phosphorus, arsenic and antimony. Phosphine, arsine, 398 00:29:19.440 --> 00:29:23.400 and stibene were given considerable attention during the first and 399 00:29:23.480 --> 00:29:28.039 second decades of the modern period. Phosphine or hydrogen phosphid 400 00:29:28.440 --> 00:29:32.759 discovered in seventeen eighty three by Jenjibray, and its composition 401 00:29:32.920 --> 00:29:36.559