108 



Frederick Guthrie on Salt- Solutions 



For curve see fig. 2. Although the temperature here 

 shown for the cryohydrate is distinctly below zero, proving 

 that the oxalate is not, like a colloid, molecular ly free from the 

 water, yet I am not assured that I have been able to form a 

 true cryohydrate in the solid form. The ice and salt separate 

 apart, the former adhering to the glass, and the microscopic 

 transparent crystals of the latter remaining in suspension in 

 the solution. The first analysis, indeed, showed greater per- 

 centage of salt at — 0°*4 than at 0°, the difference amounting 

 to about 0*28 per cent, on the highest. This is an impossible 

 result. The state of things clearly arose from the circum- 

 stance that the liquid cryohydrate was enriched by the sus- 

 pended crystals. The solution at 0° was also abnormally rich 

 from the same cause. It was only on keeping the solution in 

 ice for twenty-four hours that the zero amount above given 

 was obtained, and by keeping the zero solution for twelve 

 hours in a weak freezing-mixture (nitre and ice) that the 

 cryohydrate (in a liquid form) was got. 



§ 247. Salicylate of Aniline* '.—-The above remarks are again 

 applicable to this salt. So sparingly is it soluble in water at 

 all temperatures, and so close below 0° is the cryohydrate, that 

 no examination of this region was practicable. Of a solution 

 at 0°, 10'3720 grams gave 0-0295 gram, or 0'28 per cent. 

 The cryohydrate formed at -0°*05 or -0°*07. Of it, 10*0310 

 grams gave 0*0245 gram, or 0*24 per cent. A solution satu- 

 rated at 6°*2 gave 0*0710 gram salt out of 10*9270 grams 

 solution, that is 0*65 per cent. Even at 16°* 8 there was only 

 obtained 0*0800 gram from 10*3450 grams, or 0*77 per cent. 



Table LIV. 



Per cent, of 

 salicylate 

 of aniline 

 by weight. 



Per cent, of 



water 

 by weight. 



Temperature 



at which 



solidification 



begins. 



Nature of 

 solid. 



0-24 



0-28 

 065 

 0-77 



9976 

 99-22 

 99-35 

 99-63 



- 006 





 + 6-2 

 + 16-8 



Cryohydrate. 

 Salt. 



For the graphic representation of these numbers see fig. 2. 



* The salicylate of aniline has not, I believe, been previously described. 

 It is obtained by mixing an alcoholic solution of aniline with the acid. 

 It fuses at about 150°, and cannot be distilled without decomposition. It 

 is slightly soluble in bisulphide of carbon ; soluble in ether, hot or cold ; 

 soluble in alcohol, hot or cold; soluble in hot benzol, very sparingly in 

 cold. 



