132 



CHEMISTRY. (CHEMICAL PHYSICS.) 



this is not the case. They liquefy together. In 

 evaporation, however, the nitrogen boils off be- 

 fore the oxygen. Between the poles of the mag- 

 net all the" liquefied air goes to the poles ; there 

 is no separation of the oxygen and nitrogen. 

 Liquid air has the same high insulating power 

 as liquid oxygen. The phenomena presented by 

 liquefied gases offer an unlimited field for in- 

 vestigation. At 200 C. the molecules of mat- 

 ter have only one half of their ordinary velocity, 

 and have lost three fourths of their energy. At 

 such low temperatures they seem to be drawing 

 near what might be called " the death of matter," 

 so far as chemical action is concerned ; liquid 

 oxygen, for instance, has no action on a piece of 

 phosphorus, or potassium, or sodium dropped 

 into it. The author once thought, and pub- 

 licly stated, that at such temperatures all chem- 

 ical action ceased. That statement requires some 

 qualification, because a photographic plate placed 

 in liquid oxygen can be acted upon by radiant 

 energy, and at a temperature of 200 C. is still 

 sensitive to light. 



In H. E. Baker's experiments on the influence 

 of moisture on chemical action, ammonia was 

 dried as completely as possible by freshly ignited 

 lime ; on then subjecting it to the action of phos- 

 phoric anhydride very little of the gas was ab- 

 sorbed. Hydrogen chloride was dried first by 

 sulphuric acid and finally by a week's contact 

 with phosphoric anhydride. On mixing am- 

 monia and hydrogen chloride, dried in this way, 

 no ammonium chloride fumes were produced, 

 and no contraction was indicated by the mercury 

 gauge attached to the apparatus ; it was there- 

 fore concluded that ammonia and hydrogen chlo- 

 ride do not combine when dry. Union at once 

 occurs, however, on introducing a small quantity 

 of moist air. In like manner sulphur trioxide 

 would not unite with lime, barium monoxide, or 

 copper oxide. Furthermore, no brown fumes 

 were produced on mixing dry nitric oxide with 

 dry oxygen. 



While making his experiments on the pro- 

 duction of alloys by contact of the constituent 

 metals, W. Hallock applied his method to some 

 chemical reactions the common freezing mix- 

 ture of salt and ice, sodium and potassium ni- 

 trate, potassium, calcium and ammonium chlo- 

 ride, and sodium and potassium hydrate the 

 materials all having first been cooled far be- 

 low the centigrade zero so as to assure perfect 

 dryness. The result was always the same lique- 

 faction and union at temperatures below the 

 melting point of either substance, but above that 

 of the product. The questions were suggested : 

 Wherein do the results differ from the new 

 method of forming alloys ? and, Are the metals 

 combining to form alloys in the new way a freez- 

 ing mixture ? The result of a test made with 

 potassium and sodium indicated an affirmative 

 answer to the latter question. In experiments 

 in which ice is used it is hardly safe to suppose 

 a chemical action between solids, but rather that 

 the vapor from the ice attacks the metal, form- 

 ing the hydrate which unites with other ice, 

 forming a solution, which is then further acted 

 upon by the metal. In view of these and other 

 considerations, it is suggested that perhaps many 

 substances have a slight vapor tension at tem- 

 peratures considerably below their melting 



points, and are surrounded by a thin atmosphere 

 of their own Yapor over their clean surfaces, and 

 that it is only necessary to bring two such at- 

 mospheres to interpenetration in order to initiate 

 the reaction, which will then continue, provided 

 the product escapes easily and does not clog the 

 operation. Mr. Hallock believes that chemical 

 action may take place between solids wherever 

 the product or products are liquid or gaseous, 

 even though the reagents are solid, with perhaps 

 the added condition that both the reagents be 

 soluble in the liquid produced. If this be true, 

 his new method of forming alloys is simply a 

 special case of this general principle. 



The power of different metals to occlude hy- 

 drogen has been determined by G. Neumann 

 and P. Streinz, as follows : Palladium is capable 

 of absorbing hydrogen to the extent of 502-35 

 times the volume of the metal ; platinum sponge, 

 49-30 times its volume a figure that varies con- 

 siderably from that found by Graham ; gold, in 

 different experiments, from 37-31 times to 46-32 

 times its volume a value higher than that ascer- 

 tained by Graham ; silver, according to the au- 

 thors' experiments, none according to Graham, 

 0-211 times its volume: iron, in a state of fine 

 division, 19-17 times its volume ; copper, 4-J 

 times its volume; nickel, 17-57 volumes. The 

 absorption of hydrogen by cobalt is rather large, 

 and the metal, when charged with hydrogen, 

 becomes incandescent in a current of oxygen. 

 The occlusive power of some metals for hydro- 

 gen decreases on a repetition of the experiments. 

 The attention of the authors was called to this 

 subject by the view that lead, as the negative 

 pole of a secondary element, is capable of oc- 

 cluding hydrogen. On testing the metal, it oc- 

 cluded, in one experiment, 0-15 time, and in the 

 other, O'll time its volume of the gas. Neu- 

 mann has examined the behavior of the precious 

 metals with oxygen. Silver absorbed 4'09 vol- 

 umes; while Graham found the absorption to be 

 from 6 - 15 to 7'4 volumes; gold absorbed 48-49 

 volumes, while Graham observed no absorption 

 a difference attributed by Neumann to the tem- 

 peratures of the experiments; platinum occluded 

 77-14 volumes. With palladium the author 

 found a formation of suboxide, since the residue, 

 after treatment with oxygen, contained 6-99 per 

 cent.; while Pd a O contains 7-33 per cent. He 

 believes that the absorptions of oxygen depend 

 on a power of the metals to become oxidized at 

 about 450 C., the temperature of the experiment. 



The observation of A. S. Johnson, made in 

 1876 and 1879, that hydrogen gas, occluded in 

 copper turnings, is a source of error on the side 

 of excess in hydrogen determinations, is con- 

 firmed by Neumann. Mr. Johnson found that 

 metallic copper occludes varying quantities of 

 hydrogen, according to the state of its surface ; 

 that alternate oxidation and reduction of the 

 same copper tends gradually to diminish the 

 weight of the occluded hydrogen ; that copper, 

 which has occluded hydrogen, parts with its oc- 

 cluded gas when heated to redness in pure nitro- 

 gen, but does not part with it when heated to 

 redness in a vacuum ; that pure copper occludes 

 no hydrogen ; and that the presence of sulphur 

 tends to increase occlusion. 



It is well known that the amount of gas capa- 

 ble of being held in solution by a given liquid is 



