XeW YoUK AgRICULTUKAL ExPEKIMEiST SxATIOX. 327 



On the basis of 8 representing the true number of valencies satis- 

 fied in the basic-calcium caseinate molecule, the molecular weight 

 of casein is Trrs^s-rrcr-T or 8888 + . Robertson^ reaches similar 

 results by deducing the molecular weight of casein in several 

 different ways. This would also make the equivalent weight of 

 casein equal to --^ or 1111. This value is in close agreement with 

 the equivalent weight assigned by other workers to casein prepared 

 from cow's milk. Laqueur and Sackur^ give about 1135; Mat- 

 thaiopoulos^ gives 1131.5; Long' gives 1124. 



As a result of the work here reported, it would seem possible, 

 theoretically, to prepare a series of not less than eight combinations 

 of casein with each of the basic elements studied. 



According to what we have reason to believe at the present time, 

 not less than four of these combinations have been prepared. 

 Using the calcium compounds, we have the following series: 



Name of compound. I Grams Ca for 100 grams of casein. 



Mono-calcium caseinate . . . 



Di-calcium caseinate 



Neutral calcium caseinate. 

 Basic calcium caseinate. . . 



0.22 (equal to 0.31 CaO) , 

 0.44 (equal to 0.62 CaO), 

 1.07 (equal to 1.50 CaO), 

 1.78 (equal to 2, 50 CaO), 



Valencies 

 satisfied. 



1 

 2 

 5 



It is noticeable that in this series compounds arc absent repre- 

 senting valencies of 3, 4, 6 and 7. Whether such compounds can 

 be prepared no one can say at present. 



PART II. PARACASEIN AND SOME OF ITS COMPOUNDS. 



Tlie term paracasein is generally applied to the precipitated 

 protein compounds formed by treating milk with rennet-extract. 

 The relations between casein and paracasein are not satisfactorily 

 understood as yet. Little study has been given to the compounds 

 formed by paracasein. Van Slyke and Hart^ have shown that 

 paracasein combines with calcium to form a compound neutral to 

 phenolphthalein, containing about 2.40 per ct. CaO (1.71 per ct. Ca), 

 or 1 gram of paracasein combines with 8.55 x 10'^ gram equivalents 

 of calcium. They also found a compound neutral to litmus, in 

 which there was about 1.50 per ct. CaO (1.07 per ct. Ca), or 1 gram 

 of paracasein combines with 5.35x10'* gram equivalents of cal- 

 cium. According to their results, the compound containing the 



^Jour. Physical Chem., 15: 179, 1911. 



-Hofmeistefs Beiirdge, .3: 193, 1902. 



■'Ztsch Analyt. Chem., 47: 492. 1908. 



*Jour. Am. Chem. Soc., 28: 372, 1906. 



5 N. Y. Agr. Exp. Sta. Bull. No. 201, and Am. Chem. Jour., 33: 472, 1905. 



