DAIRYING. 341 



The reasons urged for a legal distinction between whole -milk and 

 skim milk cheese are that in the eyes of the food laws of the State 

 skim milk cheese is an adulterated food; that the motive which lies at 

 the basis of its manufacture is wrong, "because it expects to gain 

 something from selling an adulterated article for more than it is 

 worth; '' that it is of less value than whole milk cheese, is much less 

 digestible, and is more rapidly perishable; and that its manufacture 

 and sale tends to demoralize dealers and to injure the growth and 

 prosperity of the cheese industry. 



The arguments for and against the proposed change in the law are 

 considered. 



The behavior of milk to rennet, and the "rennet test" of milk, 

 R. Leze and E. Hilsont {Compt. Rend., 118 {1894), p. 1069, and Jour, 

 de VAgr., 1894, May; ahs. in Milch Ztg., 23 {1894), .A^o. 23, pp. 303, 363, 

 and Chem. CenthJ., 1894, II, Xo. 5, p. 259). — The authors studied the 

 action of rennet on milk with a view to applying the results in testing 

 milk for freshness and quality. They used a solution of 1 part com- 

 mercial rennet extract to 10 parts of water, adding 1 cc. of this to 

 100 cc. of milk, and observing the length of time required to curdle 

 the milk at 35° C. Aerated milk curdles more slowly, and milk treated 

 with carbonic acid more rapidly. The efl'ect of carbonic acid was also 

 apparent in the fresh milk, which curdled more quickly than after 

 standing 2 or 3 hours. The milk solids, and esjiecially the fat, were 

 found to accelerate the action of rennet. Thus skim milk curdled in 6 

 minutes and 4 seconds, milk mixed with 20 per cent of cream in 4 

 minutes and 24 seconds, and milk with 50 per cent of cream in 2 minutes 

 and 48 seconds. The addition of starch or sawdust to milk also has- 

 tened the action. Previous heating, on the other hand, especially 

 above 70^ C, delayed the action, and boiled milk curdled very slowly 

 and imperfectly. The addition of water to milk retarded curdling 

 somewhat. Pure milk which curdled in 3 minutes and 11 seconds 

 curdled in 3 minutes and 14 seconds when 5 per cent of water was 

 added, in 3 minutes and 14 seconds with 10 per cent, in 3 minutes and 

 20 seconds with 20 per cent, iii 4 minutes and 8 seconds with 30 per 

 cent, and in 5 minutes and 49 seconds with ."50 per cent of water. Sour- 

 ing shortened the time required for curdling with rennet, as might be 

 expected. 



The authors draw the following conclusions as to the indications of 

 the quality of milk from the rennet test: Milk of good quality curdles 

 in 3h to 4 minutes, the curd being clean, homogenous, and a clear por- 

 celain white. If a longer or shorter time than this is required, or if the 

 curd is crumbly, tough, or dull-colored, the milk is of doubtful quality, 

 and should be submitted to closer analysis. Too slow curdling indi- 

 cates the addition of water or an alkaline preservative, or possibly 

 previous heating. Very rapid curdling indicates the addition of foreign 

 substances, or that the milk has commenced to sour, A milk which 



