22 



just removed from curd may vary from 0.10 to 0.15, and this will 

 increase up to the end of the cheese-making process. Fresh whey 

 shows less acid than the milk from wliich it conies, because the whey 

 does not contain the calcium, casein of the milk, this compound by 

 itself showing an apparent acidity of 0.08 or 0.09 per cent. 



15. Composition of cheese, — The following figures give the average 

 composition of cheese when green and when ripened : 



Water 

 Solids. 

 Fat... 



In green 

 cheese. 



Per cent. 

 36. 80 

 63.20 

 33.75 



In 

 ripened 

 cheese. 



Per cent. 

 31.75 

 68.25 

 36.75 



Paracasein, etc. 

 Ash, acid, etc.. 



In green 

 cheese. 



Per cent. 



23.75 



5.70 



In 

 ripened 

 cheese. 



Per cent. 



25.50 



6.00 



16. The value of cheese as food. — Cheese is one of our most concen- 

 trated and cheapest forms of food and furnishes a large amount of 

 protein (reference No. 3, p. 98). 



EXPERIMENT AND PRACTICE WORK, SECOND LECTURE. 



Time required for experiments. — The actual work required in getting 

 the experiments started may not occupy more than half an hour, if 

 one determines solids in only one sample of milk and whey, but the 

 work can not be completed until three or four hours later, when evap- 

 oration is complete. It will be well to make several different deter- 

 minations either on the same or on different samples. 



Apparatus required. — (1) Testing scale with set of metric weights 

 weighing to 10 milligrams. (2) Small, flat-bottomed evaporating 

 dishes 2^ or 3 inches in diameter. Small, granite-iron or tin dishes 

 will answer. (3) An arrangement for heating these dishes directly 

 over boiling water or live steam. A pail could be used provided with 

 a close-fitting cover, in which are cut holes nearly as large in diameter 

 as the small evaporating dishes used. 



1. Approximate determination of milk solids. — Weigh a small 

 granite-iron or bright tin basin, run in 10 cubic centimeters of milk 

 and weigh again. (Weigh to within 10 milligrams.) Then heat the 

 dish over live steam or boiling water for three or four hours. After 

 wiping dry and cooling weigh again. Subtract the weight of the dish 

 from the last weight, which gives weight of dried milk or milk solids. 

 Divide this by weight of milk used. The result is the per cent of 

 solids in milk. While the appliances used will not give accurate 

 results, it is desirable to go through the work to know something of 

 the method of determining solids. 



