124 



MANUAL OF MILK PRODUCTS 



Cream test bottles (Figs. 28, 29) 



Use standard 9-gram 50 per cent cream test bottles. The 

 divisions represent .5 per cent, 1 per cent, and 5 per cent. The 

 t 5 per cent divisions bear a figure to the left of 



the graduation. Two, styles 

 of these bottles may be used, 

 short-neck bottles and long- 

 neck bottles. For further de- 

 tails regarding standard cream 

 test bottles see Agricultural 

 Experiment Station Circular 

 No. 41. 



IS 



I 



Adding the acid 



Commercial sulfuric acid, 

 specific gravity 1.82 to 1.83, 

 should be used. The amount 

 of acid to be used varies with 

 the temperature and richness 

 of the cream, averaging about 

 8 to 12 c.c. The most satis- 

 factory guide, indicating the 

 amount of acid needed, is the 

 color of the mixture of acid 

 and cream immediately after 

 shaking. Add acid until, when 

 properly shaken and all the white curd has 

 disappeared, the mixture has a coffee-brown 

 color. A light brown color shows that more 

 acid is needed. A black color immediately 

 after shaking indicates too much acid. 



When adding the acid, the bottle should 

 be held in an inclined position and should 



Fig. 28. — The 

 50 per cent nine- 

 gram short-neck 

 standard cream 

 test bottle. 



9S* 



Fig. 29. — The 

 50 per cent nine- 

 gram long-neck 

 standard cream 

 test bottle. 



