186 ANIMAL AMIDES. 



agulum by acids falls to the bottom of the serum, but that by al- 

 kalies swims on the surface.* 



Neumann also made some experiments on cheese, a well-known 

 preparation of curd. He tried the action of water, nitric acid, 

 sulphuric acid, muriatic acid, and caustic alkalies, both fixed and 

 volatile ; and found that they dissolved cheese either partially or 

 completely. 



Scheele examined milk and curds in 1780, and was the first 

 person who compared curds with coagulated white of egg. He 

 showed that the properties of both were the same. Milk is coa- 

 gulated by acids, and the coagulum formed is a compound of the 

 acid employed and curd. The mineral acids when used in ex- 

 cess dissolve a portion of the precipitate, but the vegetable acids 

 dissolve little or nothing. Hence the reason why more curd is 

 obtained when milk is coagulated by vegetable than by mineral 

 acids.f 



The first attempt to make a regular analysis of milk was by 

 Parmentier and Deyeux, in a memoir which gained the prize of- 

 fered by the Society of Medicine of Paris, for the year 1790.J 

 These chemists examined the curd of milk in considerable detail, 

 and determined many of its properties, though they did not ob- 

 tain it in a state of purity. They distinguished it by the name 

 of matiere caseeuse. 



Fourcroy in his Systeme des Connoissances Chimiques, pub- 

 lished about the beginning of the present century, gives a pretty 

 detailed account of the curdy part of milk, chiefly taken from the 

 Memoir of Parmentier and Deyeux. He distinguishes it, as these 

 chemists did, by the name of caseous matter. 



In 1808, the second volume of the Animal Chemistry of Ber- 

 zelius was published in Stockholm. It contains an excellent 

 analysis of milk, || and a detailed examination of the characters 

 of the curdy portion, which he distinguishes by the name of ost, 

 (cheese). He pointed out some difference in the characters of 



* Lewis's Neumann's Chemistry, p. 573. 

 f Scheele's Chemical Essays, p. 265. 



\ See an abstract in Ann de Chim. vi. 183. The memoir itself was publish- 

 ed in Paris in 1800. 



Vol ix. p. 515 of the English translation. 

 II Forelassningor i Djuskemier, ii. 409. 



