446 OSMOTIC PRESSURE. 



of water, the depressions observed would be i'857; '^y2\ 

 5-569 and 7-36. 



Sugar gives one ion per molecule, potassium chloride two, 

 barium chloride three, and potassium ferricyanide four ions. 

 Tlie numbers given above are equal to i'857 x i, 2, 3 and 4. 

 i.e., the observed depression is proportional to the number of 

 ions formed on solution. 



The above results are typical of hundreds of others, and we 

 may consider that the ionic theory of solution is now estab- 

 lished upon a sound basis, that the theory of osmotic pressure 

 is intimately connected with the theory of electrolytic conduc- 

 tion, so that one is practically dependent upon the other. It 

 has been of the greatest use to the chemist in enabling him to 

 find the molecular weight of bodies such as starch, which could 

 not be heated without decomposition, and metals which could 

 not readily be vaporised; but both these bodies, by dissolving 

 in suitable solvents, produce a depression of the freezing point 

 or a rise of the boiling point, and knowing that the molecular 

 depression is constant with a particular solvent, a molecular 

 weisrht could be calculated. 



THE TERCENTENARY OF THE TELESCOPE. 



By H. B. Austin, F.R.A.S. 

 (Not printed.) 



STATE SOCIALISM OR NATIONALISATION 



By J. R. Leech, M.D. 

 (Not printed.) 



NITRIDES AND ARGIDES.— In Vol. 43, No. 8, of 

 Bcrichtc der Dcutschcn Chemischen GeseUschaft, Eischer and 

 Schroter give an account of their recent researches into the 

 possibilities of effecting chemical combination between the 

 metals and nitrogen or argon. A number of unstable nitrides 

 were formed from the metals in the right hand vertical rows 

 of the columns in the Periodic Table, those of higher atomic 

 weight — the Cadmium, Mercury, Lead, and Bismuth nitrides, 

 for instance — being explosive, and the others slightly so or 

 else readily decomposed on g'ently warming. No argon com- 

 pounds could be formed in arc discharges in pure liquid argon 

 between metallic electrodes, and it is inferred that, if they 

 exist at all, they must be even more explosive than Cadmium 

 nitride, inasmuch the method used for the production of the 

 latter compound fails to effect chemical combination in the 

 case of argon. The action of forty-five metals on liquid argon 

 was investigated under the arc produced by Eischer and 

 Iliovici's apparatus. Some of the metals were unaffected, 

 while others were reduced to black powders, the latter in- 

 variably representing the right hand vertical rows of the 

 columns in the Periodic Table. 



