The Marschall Rennet Test consists of a graduated cup (a) with a fine hole for an outlet in the bottom. One cubic centimeter of a standard rennet extract is diluted with water in the glass bottle (c). The cup is filled with milk and placed on the corner of the cheese vat, the milk being allowed to run through the fine hole in the bottom of the cup. The moment the surface of the milk reaches the upper mark of the graduation in the cup the diluted rennet extract is added and quickly stirred into the milk with the spattle (d). When the milk begins to curdle it stops running out. The sweeter the milk is the more will run out before coagulation stops it and the mark on the scale at which it stops indicates the degree of acidity or ripening. The point is to have the milk alike every day and if, for instance, the cheesemaker has found that his cheese is best if he adds the rennet to the milk in the vat when the test shows 2½, he wants to ripen the milk to that degree every day. So, if the test shows 3 or 4, it indicates that the milk is not sufficiently ripened and it should be allowed to stand warm for a longer time before it is set with rennet. Footnote 7: The Acidemeter for making an Acid Test is described in Chapter I. Footnote 8: Rennet (see under “Ferments” in Chapter I) is prepared from the third division of the stomach of the suckling or milk-fed calf. Fifty years ago cheesemakers used to make their own rennet by soaking salted calves’ stomachs in sour whey, and our grandmothers used a piece of a dry, salted stomach to make Junket or “Curds and Whey.” About 1868, Christian Hansen, of Copenhagen, Denmark, began the preparation of Commercial Rennet Extract which soon supplanted the home-made rennet in all countries wherever cheese was made. Nowadays rennet in liquid or powder or tablet form for cheesemaking, and Junket Tablets for milk puddings, are prepared pure and of known strength in laboratories and handled by druggists and dealers in dairy supplies. The fresh stomachs are saved by the farmers or butchers and are either blown up and dried in the air protected from sunlight and rain, or split lengthwise and spread out flat and salted on both sides. In the laboratory the ferment is extracted by chemicals and a pure, clear liquid extract is prepared, of uniform strength and good keeping quality. Or the extract is condensed into a powder which again is compressed into tablets of great strength.