Mr. W. K. Sullivan on the nature of Lactic Fermentation. 2'05 



formed. A very small portion of the caseine would be sufficient 

 to perform the function of ferraentj so that the great mass might 

 have been changed into albumen. 



With a view to ascertain whether the relative quantity of albu- 

 men was in accordance with this view of the case, and also 

 whether there remained any dissolved caseine not converted into 

 albumen, I added, as Lehmann recommends, a strong solution of 

 chloi'ide of ammonium to the acid solution, and boiled it for some 

 minutes, so ag to wholly coagulate the albumen ; the boiled liquor 

 was filtered, and a solution of sulphate of magnesia added, and 

 again boiled : no precipitate was formed. It is usually considered 

 that if, in such a case, caseine be present, it would be precipi- 

 tated. But, although no substance having the properties usually 

 attributed to caseine was present, the whole of the azotic matter 

 was not precipitated by the addition of the alkaline salts. A 

 considerable quantity of some other substance or substances 

 remained in solution. Whatever this substance was, it putrefied 

 very rapidly on exposure to the air, the liquor becoming in two 

 or three days full of fungi and infusoria. 



This easily putrescent substance may, however, have been 

 formed after the metamorphosis of the caseine into albumen. 

 But, on the other hand, it is stated that in the putrefaction of 

 fibrine there is produced, among other things, a substance which, 

 according to Strecker, has the composition and all the characters 

 of albumen* ; and, again, some chemists have been led to believe 

 that caseine, as it is extracted from milk, is really a mixture of 

 two different bodies. Schlossbergerf digested well- washed 

 caseine with dilute hydrochloric acid, and obtained a solution 

 which, on neutralization with carbonate of ammonia, gave a 

 white slimy body, which filtered with difficulty, Avhile another 

 body remained dissolved and was precipitated by hydrochloric 

 acid in excess. Schlossberger found that the first body con- 

 tained sulphur, and the second not. But, even after the sepa- 

 ration of the second body, another substance appeared to have 

 been left behind. Gerhardt did not think the experiments of 

 Schlossberger and others conclusive : undoubtedly it may with 

 truth be objected, that the diffei'ent substances just described 

 were pi'oducts of the decomposition of the true caseine resulting 

 from the action of the hydrochloric acid. This objection does 

 not, perhaps, apply with the same force to the following experi- 

 ment of Mulder^. Having freed milk as much as possible from 

 blood-globules, by the addition of common salt, he coagalatcd 

 the milk with dilute hydrochloric acid ; on separating the coa- 



* Gerhardt, Chimie Ortjanique, vol. iv. p. 462. 

 t Ann. der Chem. und Pharm. vol. Iviii, p. 92. 

 X Uerzelius's Juhresbericht, vol. xxvi. 



