858 Milk and Its Products 
lub and the temperature maintained as nearly as possible at 98° F. for 
six to twelve hours, when they may be examined. A solid, firm curd, 
without disagreeable odor or flavor, shows that the milk is pure and 
clean and has been properly handled. Impurities in the different sam- 
ples are indicated by the presence of small round holes (gas cells) seen 
in the curd when it is cut across with a knife, or by various disagree- 
able odors that may be detected when the covers to the jars are removed. 
The apparatus for this test in an improved form is now furnished by 
most of the dairy supply houses. 
Monrap Raennet Test 
This test is figured and described on page 241. It is used as fol- 
lows: To determine the ripeness of milk for cheese making, put 5 c. 
e. commercial rennet in a 50 c. c. flask and fill with water to the mark. 
Put 200 c. c. of milk at 86° F. in a suitable tin cup, and allow it to float 
in the vat. Add 5c. c. of the diluted rennet, and note carefully the time 
required for the first appearance of coagulation. The time required 
will depend upon the amount of milk and rennet used, the strength 
of the rennet, the temperature and the ripeness of the milk. All except 
the last remaining constant from day to day, the degree of ripeness is 
measured by the time required for coagulation. The riper the milk the 
shorter the time; ordinarily from one and one-half to two minutes will 
be required. The diluted rennet must be made fresh every day. 
MarscHatt Renner TEst 
For a description and cut of this test, see page 242. Directions for 
its use: To determine the ripeness of milk for cheese making, fill the 
vessel to the 0 mark with milk, add a pipette full of commercial ren- 
net, stir quickly, and place in such a position that the milk may flow 
freely from the orifice. When the milk ceases to flow, note the number 
of graduations exposed. The riper the milk the less the number of 
exposed graduations. 
Hor Iron Trst 
A test used to indicate the maturity of curd in cheese making. The 
maturity is usually coincident with the amount of lactic acid present, 
so that the test is commonly called the hot iron test for acid. 
The test is made by heating a bar of iron just short of redness, or 
so that it will hiss readily. A mass of curd is squeezed in the hand till 
all the whey possible is pressed out. The curd is then applied to the 
