-}.'5 1 RioroKr ok the Depaktjmeat of Ciiemistiiv ok the 



The percentage of phosphorus would give n(^^:TT) 100 = n 4372 — . 

 The value of n appears to be 1 and each molecule of paracasein 

 would contain one atom each of sulphur and phosphorus. 



Theoretically, it should be possible to make a series of four salts 

 of paracasein with bases. We have prepared three, those in which 

 one, two and four valencies are satisfied. 



ACTION OF RENNET ENZYM ON CASEIN IN FORMING PARACASEIN. 



The action of the principal enzym contained in rennet-extract in 

 splitting casein into two molecules of paracasein is further shown 

 by the following experiment: Five grams of casein are dissolved 

 in 250 cc. of ^ KOH. Using the volumetric method given on page 13, 

 it was found that 44.5 cc. of ^ HCl could be added to 50 cc. of the 

 caseinate solution, containing 1 gram of casein, before a permanent 

 precipitate begins to appear. To another 50 cc. of caseinate solu- 

 tion a few drops of neutral rennet-extract are added. Under the 

 conditions of the experiment, no precipitate or curd is produced by 

 the action of the rennet-enzym. After a few minutes ^ HCl is 

 added and it is found that a permanent precipitate begins to form 

 as soon as we add only 39 cc. -j^ HCl. 



We have in hand a more extended investigation relating to the 

 action of rennet-enzym upon casein, the results of which will be 

 published later. 



PART III. COMPOSITION OF THE BRINE-SOLUBLE COM- 

 POUND IN CHEESE. 



During the manufacture and ripening of cheddar cheese and of 

 many other kinds of cheese there is always found a protein that is 

 soluble in a warm 5 per ct. solution of sodium chloride. The exis- 

 tence of such a substance in cheddar cheese was first brought to 

 attention by work done at this Station.^ The presence of this 

 brine-soluble protein was shown to be associated in some way with 

 the formation of acid in the cheese and, on the basis of some early 

 experiments. Van Slyke and Hart were led to conclude erroneously 

 that the substance consists of a combination of paracasein and 

 lactic acid (called by them paracasein mono-lactate) , which by the 

 addition of more lactic acid becomes insoluble in dilute brine solution, 

 forming a compound which they mistakenly regarded as paracasein 

 di-lactate. As a result of later work^ they changed their first views 

 and came to the conclusion that the so-called paracasein mono- 

 lactate is simply the uncombined protein, paracasein, and that the 

 so-called paracasein di-lactate is a compound of paracasein and 



1 N. Y. Agr. Exp. Sta. Bui. No. 214, 1902. 



2 N. Y. Agr. Exp. Sta. Bui. No. 261, 1905. 



