Chemistry and Physics. 153 



tration. This seems to be the case in the absorption of hydrogen 

 by palladium, the gas being at first absorbed under a constant 

 pressure of 225 mm. until 600 parts by volume have been taken 

 up, producing Pd 2 H. After this the-amount of hydrogen absorbed 

 is proportional to the pressure. Again analogy with liquid solu- 

 tions would lead us to expect a redaction in the vapor-pressure of 

 a solid when it takes any other substance into solution ; and we 

 find that many isomorphous mixtures are more stable and do not 

 effloresce as readily as their constituents. Moreover, this reduc- 

 tion of the vapor pressure of a solid by the introduction of foreign 

 material is of importance in considering the effect which the 

 separation of a solid solution in place of the pure solvent has on 

 the lowering of the fusing point. For since the freezing point of 

 a solution is the point at which the vapor-pressure of the solution 

 and of the separating solid is the same, the smaller the vapor- 

 pressure of the solid the higher will be the melting or freezing 

 point of the solution. Hence the separation of a solid solution 

 from a solvent in place of th© pure solvent, would make the fall 

 in the freezing point too high or would cause too small a depres- 

 sion of the freezing point. This occurs most often in those cases 

 in which we might expect the formation of a solid solution from 

 the union of solvent and dissolved substances as in a solution of 

 metacresol and parabromophenol in phenol, of aldoxime in acetox- 

 ime and of thiophene and pyridine in benzene. Evidently if the 

 Raoult methods are applicable to solid solutions, these should be 

 available for determining molecular mass. From the proportion- 

 ality, for example, between the amount of hydrogen absorbed by 

 palladium and the gas-pressure, it would seem that the conclusion 

 that free hydrogen has the same molecular composition as that 

 held in solution by palladium, is a rational one. — Zeitschr. Phys- 

 ikal. Chem., v, 322; J. Chem. JSoc, lviii, 1044, October, 1890. 



G. E. B. 



4. On the Properties of Liquid Chlorine. — Knietsch has 

 made an extended investigation upon the physical properties of 

 liquefied chlorine. He finds that from its melting point, given by 

 Olsewski at —102°, its pressure increases from 37*5 mm. of mer- 

 cury at —88° to 560 mm. at —40°, its mean expansion-coeffi- 

 cient between these limits being 0*001409. At — 33*6°, its vapor- 

 pressure is 760 inms.; and this is therefore its boiling point. From 

 this temperature to —10°, under a pressure of 2 "6 3 atmospheres, 

 its expansion-coefficient is 0*001793. At 0°, its pressure is 3*66 

 atmospheres and its coefficient of expansion is 0*001978. At 20°, 

 the pressure is 6*62 atmospheres and its coefficient 0*002190. At 

 60°, its pressure is 18*6 atmospheres and its coefficient 0*003460. 

 At 100°, its pressure is 41*7 atmospheres and at 146°, its critical 

 temperature, it is 93*5 atmospheres. — Lieb. Ann., cclix, 100 ; Per. 

 Perl. Chem. Ges. } xxxii, Ref. 629, November, 1890. g. f. b. 



r>. On the Preparation of Chromium by means of Magnesium, 

 — Glatzel has experimented successfully to obtain metallic 

 -chromium by reduction with magnesium, using for the purpose 



