192 



EXPERIMENTAL FAR3IS 



9-10 EDWARD VII., A. 1910 



As pointed out in our discussion of this subject in the last annual report, rain is 

 very much richer in nitrogen compounds than snow, but comparing the above with 

 similar data for the year previous, the present results show a much greater difference. 

 This is due to the smoke-laden atmosphere of the autumn months to which we have 

 already referred. The largest increase is in the free ammonia, which, taking the 

 average for twelve months, is between three and four times that recorded for the year 

 ending March, 1908. 



The average composition of the snow is remarkably close to that of the preceding 

 winter, though, the snowfall (96-25 inches) being less than that of 1907-8 (133 inches), 

 the total amount of nitrogen thus furnished is not as large. 



HART'S CASEIN TEST. 



This method for determining the percentage of casein in milk was devised at the 

 Wisconsin Experiment Station, and has for its object the valuation of milk, presum- 

 ably in conjunction with the results of the Babcock test, for cheese-making purposes. 

 It is stated to be ' accurate, simple, and requiring but a shore time to make the test.'* 



The principle of the test lies in the precipitation of the casein or curd by acetic 

 acid while the fat is kept in solution by chloroform. A centrifuge is required to make 

 the separation complete, and the amount of curd, appearing as a small, white pellet, 

 is, subsequent to a whirling of 7 or 8 minutes, read off in the graduated tube in which 

 the test is made. 



Our purpose in examining this process was to merely ascertain how closely it 

 might give the percentage of casein or curd in fresh milk and milk to which preserva- 

 tives had been added; no attempt was made to learn how far the method might be 

 useful in the practical valuation of milk for cheese making. 



Results with Hart's Casein Tester. 



1908. 



June 26. , 



July 6 . , 



July 8... 



Fat, by Babcock 



Total protein, by chemical analysis 



Casein, by chemical analysis. . 



Curd, by Hart's Tester, in fresh milk 



It II in milk, preserved 



with formaldehyde 



Fat, by Babcock 



Protein, by chemical analysis 



Casein « h 



Curd, by Hart's Tester, in frpsh milk 



II II in milk pre.served 



with corrosive sublimate 



Curd, by Hart's Tester, in milk preserved 



with bichromate of potash 



Fat, by Babcock 



Protein, by chemical analysis 



Casein • <i .... .... 



Curd, by Hart's Tester, in Ire.sh milk . . 



II 11 in milk pre .served 



with formaldehyde 



Curd, by Hart's Tester, in milk preserved 



with bichromate of potash 



Curd, by Hart's Tester, in milk preserved 



with corrosive sublimate . ....... 



Illuminata. 



3 8 

 2-65 

 1-95 

 2 20 



2-3 



Alice. 



4 



78 

 95 

 00 



4 



35 

 91 

 92 



80 



2 



4 



92 



88 







QueeTiie. 



0-2 

 3 68 

 2 89 

 2-90 



3-4 

 15 

 3-90 



2-83 



2 50 



3 8 



5 

 15 



89 

 79 

 



3-7 

 3-3 

 3 5 



•This method is fully described in Bulletin 156, Wisconsin Experiment Station, and the 

 necessary instructions for conducting the test are issued by the Fargo Creamery Supply 

 House, St. Paul, Minn., who have the apparatus for sale. 



