36 Composition of Cheese. 



Result : Curd separated in 20 minutes ; whey had the same 

 reaction as milk. 



The experiment was repeated, and found correct. 



It will thus appear that too high a temperature is not so favour- 

 able to the coagulation of the milk as a less elevated one. 

 The separation, which at 120 took place in 10 minutes, at 130 

 occupied 20 minutes. 



9^ Exp. Heated 1 pint of milk to 150, added ounce of 

 rennet. 



Result : Milk did not coagulate after 24 hours. 



Wth Exp. Heated milk to 140, added rennet. 

 Result : No coagulation. 



llth Exp. Heated milk to 135, added rennet. 



Result: No coagulation took place, even after 3 hours. 1 then 

 added another J ounce; the milk by this time had cooled 

 down, and the fresh quantity of rennet caused the separa- 

 tion of curd in less than 20 minutes. 



Thus, at 120, milk coagulates most readily ; at 130, it takes 

 a somewhat longer time ; and at 135, and upwards, it ceases to 

 coagulate. 



12th Exp. Heated 1 pint of milk to boiling-point, added Jounce 



of rennet. 



Result : No curd had separated when examined, after 24 hours' 

 standing. 



13th Exp. Heated another pint of milk to boiling-point, and 



added J ounce of rennet. 



Result : Milk did not coagulate after 24 hours. 1 then 

 added a little more fresh rennet to the cooled milk, and 

 again gently heated it, when the curd separated in less 

 than J hour. 



Thus the temperature of boiling water, and even a much lower 

 heat, destroys the action of rennet, but does not so permanently 

 change the casein of milk that it cannot be separated. 



The whey in the last experiment, again, was neutral, like the 

 milk. 



Exp. To 1 pint of fresh milk I added 10 grains of car- 

 bonate of potash, raised the temperature to 88 Fahr., and 

 added J ounce of rennet. 



Result : Curd separated in ^ hour. The milk and the whey 

 were strongly alkaline. After 24 hours the whey was 

 neutral, and then it became acid by degrees. 



Exp. To 1 pint of milk I added 20 grains of carbonate of 

 potash, heated to 90 Fahr., and added J ounce of rennet. 



