470 Mr. S. B. Schryver. Investigations on the [Mar. 6, 



'•■ •• 



N in filtrate. 



-L ci UCUtitgC 

 UX Cl/1 LflUttt'Cd. 



10 c.c. casemogenate solution — 









28 -0 







+ 10 ce N/50 CaCL, 



27 - 4 



2 -2 



+ 10 c.c. N/25 ., 



1 -2 



95 -7 



+ 10 c.c. N/20 „ 



1 -o 



96 -4 



+ 10 c.c. N/15 ., 



1 2 



95 -7 



+ 10 c.c. N/10 „ < 



1 "8 



93 -6 



+ 10 c.c. 3N/20 „ 



3-0 



89-3 



+ 10 c.c. N/4 „ 



28 -0 







+ 10 c.c. N/2 , 



28 -0 







It will be seen from the above table that nearly complete precipitation 

 takes place only when the concentration of the calcium salt in the mixture 

 lies between N/50 and 3N/20. When the concentration reaches N/4 no 

 precipitation takes place. If, however, a drop of rennet extract is added to 

 the mixture containing the higher concentrations of the calcium salt, 

 precipitation takes place after the interval of a few minutes. Without such 

 addition, no precipitation occurs even after prolonged standing. 



The product obtained by the above described reaction appears to be a 

 calcium salt produced by double decomposition between the sodium caseino- 

 genate and calcium chloride. For analysis, the precipitate was washed with 

 50-per-cent. alcohol, till free from chloride, and then with alcohol and ether, 

 and air-dried. It is a true precipitate which lacks the characteristic physical 

 properties of a clot, which are described below. 



Other Methods of Inhibiting Precipitation. — The formation of the pre- 

 cipitate can also be inhibited when the optimal proportions of calcium salt 

 are present by the addition of other substances. In view of the conceptions 

 advanced in the introduction to this paper, it was of importance to 

 investigate more especially the inhibitory action of the substances contained 

 in the milk serum. This was prepared by the addition of sufficient rennet 

 to skimmed milk. As soon as the formation of the clot was complete it 

 was broken up, and the serum was filtered off through muslin, boiled, and 

 again filtered from the protein coagulum. In addition to the action of 

 milk serum, the inhibitory action of Witte's peptone and of glycine were 

 investigated. 



Some of the results are recorded in the following table : — 



