APOSEPEDIN. 93 



tains ammonia, crystallin, and several other substances. The 

 crystallin may he obtained by the following process : 



Mix the oil with sulphuric acid, which dissolves it, leaving the 

 other substances behind. Mix the acid liquid with another base, 

 and distil. The crystallin passes over. 



Crystallin is a colourless oil, which is heavier than water. Its 

 odour is strong, and has some resemblance to that of new honey. 

 It does not react sensibly as an alkali. It is but little soluble in 

 water, yet it may be distilled over with that liquid. When ex- 

 posed to the air it becomes red, and then communicates a yellow 

 colour to water when dissolved in it. 



Sulphate of crystallin crystallizes, whether it be neutral or con- 

 tain an excess of acid. When the neutral salt is evaporated, it 

 is converted into a supersalt. It is insoluble in absolute alco- 

 hol. Its aqueous solution becomes gradually brown, and then it 

 contains sulphate of fuscin. When supersulphate of crystallin is 

 heated, it melts and concretes on cooling into a crystalline mass. 

 When exposed to a stronger heat it undergoes decomposition, and 

 there are formed sulphate of crystallin, sulphate of odorin, and a 

 great quantity of sulphate of ammonia. The charcoal remaining 

 leaves no residue when burnt. 



Phosphate of crystallin crystallizes readily, when it is neutral ; 

 but the superphosphate does not crystallize at all. Alcohol se- 

 parates the crystals by removing the excess of acid and the water.* 



CHAPTER VIII. 



OF APOSEPEDIN. t 



THIS substance was first noticed by M. Proust in 1818, J who 

 gave it the name of cheesy oxide. It was again examined, and 

 its properties ascertained by Braconnot in 1827, who distin- 

 guished it by the name of aposepedin, because it is formed when 

 casein undergoes a species of putrefaction. 



Cheese, as every body knows, consists essentially of coagulat- 

 ed casein, || from which the great quantity of liquid which it ori- 



* Unverdorben, Poggendorfs Annalen, viii. 397. 



f From. dLTtot and o-Hirtfeev, putridity. 



$ Ann. de Chim. et de Phys. x. 40. Ibid., xxxvi. 161. 



H This substance will be described in a subsequent chapter of this volume. 



