110 



CHEMISTRY. 



various salts. Ho conduces tliat the phenomenon 

 of deliquescence ill certain salts, and possibly in 

 other substances, is due to a tendency on their 

 part to form definite hydrates. 



M. Henri Moissan has proved that a great num- 

 ber of metals, such as aluminium, platinum, chro- 

 mium, uranium, vanadium, etc.. can dissolve carbon 

 when the temperature is sufficiently high, and 

 abandon it again in the nature of graphite. On 

 studying the conditions under which graphite is 

 formed 'in one and t lie same metal, iron, and by vary- 

 ing the temperature and the pressure, he has 

 reached the following results: 1. At the ordinary 

 pressure graphite is the purer the higher the tem- 

 perature at which it is formed. 2. It is more stable 

 ' in presence of nitric acid and potassium chlorate, 

 as the temperature at which it has been produced is 

 higher. II Under the influence of pressure the 

 crystals and the masses of graphite take the aspect 

 of a fused matter. 4. The small quantity of hy- 

 drogen which graphites always contain decreases 

 distinctly as their purity increases. 5. On attack- 

 ing cast iron with acids there are produced hydrog- 

 enous and oxygenous compounds which resist a 

 dull-red temperature, and which, like graphite, are 

 destroyed on combustion. 



II. B. Dixon and H. B. Baker have investigated, 

 with negative results, the question whether Ront- 

 gen rays are able to influence chemical change, 

 either by starting it or by accelerating or diminish- 

 ing it after it has been started by ordinary light. 



Discussing the subject of " Low-Temperature Re- 

 search," Prof. Dewar observes that, owing to the 

 relative pressures of oxygen and nitrogen in the 

 air, these two gases, although possessing different 

 boiling points, condense at almost exactly the same 

 temperature when air is cooled. The method em- 

 ployed for measuring low temperatures consists in 

 using a system of five thermo-junctions so arranged 

 that three of them are kept at 0, while the other 

 two are of the same metals in inverse order, so that 

 when one of them is cooled the other must be heat- 

 ed in order to preserve equilibrium. The low tem- 

 perature to be observed is thus balanced by a high 

 temperature which can easily be read off. Helium 

 appears to be less easily condensible than hydrogen, 

 and, moreover, possesses an abnormally low refrac- 

 tivity and real molecular volume. It is a remarka- 

 ble fact that fluorine, the most active of all the 

 chemical elements, in this respect resembles helium, 

 the least active of all. The ratio of the refractivity 

 of hydrogen to that of chlorine is almost the same 

 as that of helium to argon, and it is quite possible 

 that a substance may yet be discovered which will 

 be intermediate between these two elements, just as 

 fluorine is intermediate between hydrogen and chlo- 

 rine. 



In the Helmholtz memorial lecture, delivered be- 

 fore the Chemical Society, London, Jan. 23, Prof. 

 G. F. Fitzgerald contended that the. fundamental 

 conceptions underlying many of the physico-chem- 

 ical theories, such as those of osmotic pressure and 

 electrolytic dissociation, are dynamically unsound, 

 so tliat all attempts to gain an insight into what 

 occurs in solution by their aid are necessarily un- 

 successful. His language suggested that he consid- 

 ered that an unyielding adhesion to these theories 

 had led to an illogical habit, of thought upon such 

 matt 



New Substances. //<//</// and Argon. A. de- 

 scription of the remarkable physical properties pos- 

 ! by helium, which, besides its great chemical 

 apathy, distingul h it from all other gases, was given 

 by I'n.f. Ramsay in the British Association. When 

 the g;,,, j, allowed to diffuse through a porous tube 

 , Into two portions, one of which is lighter 

 than 'he other. Both give the same spectrum. These 



two portions, moreover, diffuse much more rapidly 

 than would be expected from their density, and have 

 refractive indexes which are proportional to their 

 densities, a relation which does not hold for other 

 gases. These facts are difficult to explain by the as- 

 sumption that what is called helium is a mixture of 

 two gases. The author suggested that the abnormal 

 behavior of the gas may be best explained by sup- 

 posing that all its molecules are not of exactly the 

 same weight, and that in the two portions of the 

 gas which he has obtained by diffusion a partial 

 separation of the lighter from the heavier molecules 

 has been effected. 



Prof. Ramsay and Dr. J. Norman Gallic have 

 given a list of experiments on the power of helium 

 and argon to combine with other substances, all of 

 which were attended with negative results. As- 

 suming that any compound of helium capable of 

 existence will be endothermic, the authors tried two 

 methods of producing endothermic compounds 

 where no extraneous exothermic reaction was pos- 

 sible exposure to a high temperature and the influ- 

 ence of the silent induction coil. The experiments 

 included treatment of the gas with caustic soda and 

 a solution of ammoniacal cuprous chloride, from 

 the result of which it seemed clear that argon does 

 not combine with carbon ; treatment of a product 

 rich in barium cyanide in such a way as to re- 

 cover all the nitrogen, when, no residue being left, 

 it was concluded that no argon entered into the 

 combination ; and treatment with the vapor of car- 

 bon tetrachloride under exposure to the discharge 

 from the. induction coil when the argon did not 

 enter into the reaction, and was recovered without 

 loss of volume. A larger number of experiments 

 related to attempts to produce compounds of heli- 

 um. The plan of operation was to circulate helium 

 over the reagent at a bright heat, and to observe 

 whether any alteration in volume occurred or 

 whether any marked change was produced in the 

 reagent employed. Experiments with sodium, sili- 

 con, beryllium, zinc, cadmium, boron, yttrium, 

 thallium, titanium, thorium, tin, lead, phosphorus, 

 arsenic, antimony, bismuth, sulphur, selenium, 

 uranium, chlorine, cobalt, platinum, soda lime and 

 potassium nitrate, and benzene vapor, all give 

 negative results. The authors conclude from the 

 whole that there is every reason to believe that the 

 elements helium and argon are nonvalent that is, 

 are incapable of forming compounds. 



It has, however, been found by M. P. Villard that 

 argon combines with water to form a dissociable 

 crystalline hydrate similar to the hydrates of gas 

 already known, and originating under the same 

 conditions as the others. Compressing argon with 

 about 150 atmospheres in the presence of water 

 near the freezing point, if the tube be cooled so as 

 to congeal the water on its walls, a crystallization 

 will be seen to take place, which propagates itself 

 from the cooled point ; the layer of water adhering 

 to the tube becomes transformed into colorless crys- 

 tals, visible in the lens and probably constituted 

 of a hydrate of argon. The reaction may also be 

 brought about by the presence of a crystal of the 

 hydrate obtained in a preceding experiment ; but 

 the crystals are not formed when argon is simply 

 compressed with cold water. The phenomena are 

 precisely the same as those observed with all gases 

 susceptible of yielding a hydrate. 



Experiments made by Dr. Gallic and Prof. Ram- 

 say on the behavior of argon and helium when sub- 

 mitted to the electrical discharge indicate that at 

 high pressures a discharge passes much more readily 

 through helium than through other gases ; but at a 

 low pressure, if passage of current can be inferred 

 from luminosity of spectrum, all other gases con- 

 vey current more readily than helium does, and 



