TEROXIDE OF PROTEIN. 389 



in reference to its composition and its properties. It appears from 

 the investigations of Ortloff* and Buckland W. Bullf that the 

 emulsin or synaptase obtained from almonds is not a protein- 

 compound ; indeed this is sufficiently obvious from the large 

 quantity of oxygen (26'56) which it contains. 



There are several animal substances pertaining to the protein- 

 compounds of which we have no more accurate knowledge than 

 we have of the above named vegetable substances ; in this category 

 we may place keratin, the substance deposited in horny tissue, 

 (which, according to Mulder, is the same oxide of protein as exists 

 in fibrin, but combined with a far larger quantity of sulphamide,) 

 the substance termed mucin, peculiar to mucus, and the pyin, 

 existing in pus and morbid tumours, of which full notice will be 

 taken when we treat of the chemical theory of the tissues and 

 juices. In the same manner we shall treat of pepsin and the 

 peptones when we enter into the special consideration of the 

 digestive process. 



TEROXIDE OF PROTEIN (PROTEINTRITOXYD.) 

 Chemical Relations. 



Properties. When dried, this substance is brittle, and easily 

 pulverisable, but when moist it is tough, viscid, capable of being 

 drawn out in threads, and when warmed has an odour resembling 

 that of gelatin ; it is soluble in water, but insoluble in alcohol and 

 ether, and in the fatty and volatile oils ; it has no reaction on 

 vegetable colours. It is precipitated from its solution by dilute 

 mineral acids, chlorine water, tannic acid, corrosive sublimate, the 

 salts of the oxides of lead, silver, zinc, and iron, but not by ferro- 

 cyanide of potassium, the alkaline salts, or chloride of barium. 

 With alkalies it forms neutral compounds, from which it is also 

 precipitated by metallic salts. When boiled with caustic alkalies 

 it developes ammonia, and becomes converted into a substance, 

 which, according to Mulder, is the true teroxide of his protein, 

 in accordance with his latest formula, C 36 H 25 N 4 O 10 + 3O + 3HO. 

 Composition. This body was discovered and analysed by 



* Arch.d. Pharra; Bd. 48, S. 12-27. 



t Ann. d. Ch. u. Pharm. Bd. 69, S. 145-162. 



