RENNET AND ITS PROPERTIES. 209 



As mentioned, the rennet required was formerly prepared in the 

 cheese factory itself. In such cases it was made from dried calves' 

 stomachs, which had been allowed to stand for some hours, partly in pure 

 water and partly in water which had been rendered sour with acid whey, 

 citric acid, or wine vinegar, at a temperature of from 20 to 35 C. Occa- 

 sionally, in order to preserve them, there was added to such preparations, 

 if they were made on a large scale, salt, spirits of wine, pepper, salt- 

 petre, aromatic herbs, nutmeg blossom, cinnamon blossom, laurel leaves, 

 ethereal oils, and such like. Under certain circumstances, calves' stomachs, 

 which were specially preserved and kept in the form of balls, or packed 

 in stone jars, were utilized for the preparation of the necessary rennet 

 solutions. These were obtained as follows: The calves' stomachs dried 

 in the air were first of all thoroughly separated from the fat, then 

 finely minced, and treated with 5 per cent of salt and pepper. The mass 

 was then dipped in vinegar, made into a ball, and after lying for eight 

 to twelve hours, was mixed with a quantity of butter-milk sufficient to 

 make it into a paste, and to admit of its being conveniently made into 

 balls as large as the fist. These balls were left for from three to four 

 weeks in a moderately warm, dry place, slightly smoked, and then kept 

 for use. 



Soxhlet's prescription for the preparation of good keeping rennet solu- 

 tions is as follows : 



The fresh stomach is emptied, blown up quickly, dried in the air, and 

 kept for at least three months. After the portion devoid of folds has been 

 removed, it is cut into pieces about a square centimetre in size; for every 

 100 grams of stomach 1 litre of water, 50 grams of salt, and 40 grams of 

 boracic acid are taken. It is then left to stand at the ordinary temperature 

 of the room for five days, with frequent shaking. To every litre of water 

 used, 50 grams of salt are added, and the solution is then filtered. For 1 

 litre of water there should be obtained 800 c.c. of filtrate, which should be 

 made up to a litre by the addition of 200 c.c. of a 10-per-cent salt solution 

 saturated with boracic acid. Such rennet possesses a strength of about 

 1 to 10,000, and that after lying for two months. Per litre it costs as 

 follows : 



From 3 to 3'5 calves' stomachs at 20 pfennig, 60 to 70 pfennig. 



50 grams of boracic acid at 2 marks per kilo., 10 



Salt and filter-paper, 5 



Total, .' 75 to 85 pfennig. 



Instead of boracic acid, alcohol may be used, but the rennet solution 

 obtained possesses poor keeping properties. 100 grams of calves' stomach 



(M175) O 



