102 Milk and Its Products 
it will frequently be noticed that the cream is not 
thoroughly broken up. Under such conditions, extra 
precautions must be taken to secure perfect sam- 
pling. 
Composite sampling.—In testing milk at factories, 
it is more convenient to take a sample every day, 
and make one test of the mixed samples at the end 
of a week, ten days or two weeks. In order to do 
this, it is necessary to provide a suitable receptacle 
for the milk of each patron. (Pint lightning-top 
fruit jars or milk bottles, or glass-stoppered sample 
bottles, are most convenient.) To these bottles is 
added each day a small portion of each patron’s 
milk, together with some preservative for preventing 
the milk from souring. The preservatives in com- 
mon use are bichromate of potash, corrosive subli- 
mate, and milk preservaline.. Caustic potash and 
soda may also be used. Neumann* claims to have 
had as good results with sodium nitrate as with 
bichromate of potash. Most of these substances are 
poisons, and render the milk unfit for use; the jar 
should, therefore, be plainly labeled. For this purpose 
colored corrosive sublimate is now in almost universal 
use. It gives a distinct color to:the milk, and only a 
small quantity of it is necessary to prevent the milk 
from souring. Whatever preservative is employed 
should only be used in quantity sufficient to keep 
the milk from thickening. Of the bichromate of 
potash, an amount sufficient to color the milk a bright 
lemon yellow is all that is necessary. In taking 
*Milch Zeitung, vol. xxii. p. 526. 
