Chemistry and Phyiu 2'M 



that it is a mixture; although DO separation of its constituents 

 k place on keeping a column of it in fusion for 48 hoars, the 



composition of the alloy being substantially the same throughout, 

 With thallium, 4*884 atomic units of mass lowered the solidify- 

 ing point of 100 atomic mass-units of sodium nearly twenty de- 

 grees ; being a tall for one atomic unit of mass of 4*468 degr< 

 The point of saturation was not determined. In the case of 

 mercury, although there is a considerable evolution of heat and 

 light on mixing it with the sodium, yet the atomic falls produced 

 by the successive additions do not indicate the formation of a 

 definite compound as would be expected. The addition of 3*228 

 atomic mass-units of mercury to 100 atomic units of sodium 

 lowered the solidifying point 14-12°; being 4*374° for each atomic 

 mass-unit. When thallium and mercury were both added to 

 sodium, while the atomic fall due to the Ug was 4*4 and that due 

 to the Tl was from 4-09 to 4-2 7, that produced by both was from 

 4-16 to 4*26, substantially the same. At the temperature of 

 95*43° 3*05 per cent cadmium was found to saturate sodium; this 

 quantity being 0*0475 atomic units of mass to 100 atomic mass- 

 units of sodium; the atomic fall resulting being 3*173°. The 

 addition of 3*455 atomic mass-units of potassium to 100 atomic 

 mass-units of sodium lowered the freezing point 11*56°; corres- 

 ponding to an atomic fall of 3*345°. In the case of lithium the 

 atomic fall was 1*11°, in that of lead 4*6°, and in that of indium 

 3*49, at the saturating point. — J. Chem. Soc. t lv, 666, November, 

 1889. G. F. B. 



2. On the Chlorides of Selenium. — Chabrie has subjected the 

 chlorides of selenium to investigation and has observed that the 

 tetrachloride may be obtained in large and well formed crystals 

 by heating the ordinary product to 190°-200° in the end of a 

 led tube. The vapor density of this chloride could not be 

 determined by Victor Meyer's method at 360°, even in an atmos- 

 phere of nitrogen, two molecules of this substance dissociating at 

 this point into one molecule of Se 2 Cl 2 and three molecules of 

 chlorine. Selenous chloride, however, is quite stable, distills 

 unchanged at 360° and has a vapor density of 7*95, approxi- 

 mately. With regard to the chemical reactions of the tetra- 

 chloride, the author finds that the action of benzene upon it is 

 precisely the same as that which is produced by heating to 360° ; 

 the selenium being left in the form of selenous chloride and the 

 chlorine forming chlor-benzene. If, however, the mixture is made 

 in presence of aluminum chloride, the reaction is quite different. 

 So that on treating the resulting solution with water, and frac- 

 tioning the oily product three substances are obtained: one, boil- 

 ing at 131°-133°, consisting of monochlor-benzene C 6 H 6 C1; a 

 second, passing over, under a pressure of a few millimeters of 

 mercury, at 227°-228° consisting of phenyl selenide (C 6 H 6 ) 2 Se, 

 and appearing as a yellow oil having a density of 1*45 at I960; 

 and a third, boiling under the above reduced pressure at 245°- 



Am. Jour. Scl— Third Series. Vol. XXXIX. No. 231.— March, 1890. 

 16 



