38 CHEESE MAKING. 
79. J. B. Harris Discovers the Rennet Test. 
In the middle of the eighties J. B. Harris conceived this 
idea, and used a teacupful of milk from the vat, to which he 
added a teaspoonful of rennet and noted the number of seconds 
required to coagulate the milk. When the milk was ripened 
down to a certain number of seconds, he. found that he could 
foretell approximately the time that it would take for acid to 
develop. 
80. Rennet a Powerful Agent. 
Rennet is a very powerful agent. If four ounces of extract 
is used to one thousand pounds of milk, it is one part of rennet 
to four thousand of milk, and sometimes the proportion will be 
Fig. 19.—Glass Graduates. 
as wide as one to sixteen thousand. It will te easily seen that 
since the rennet is such a powerful agent, it is not likely to be 
an entirely accurate test where a teaspoon is used for measuring 
the rennet, for then it would be difficult to measure exactly 
twice alike. Therefore, in place of the teaspoon, a minim or 
dram graduate was substituted, and for the teacup an eight- 
ounce glass graduate such as druggists use. This was much bet- 
ter than the first crude apparatus for making the test. 
