202 



one contained 3.07 and the other 4.75 per cent of fat. The average 

 per cent of fat found in the milk furnished by sixty-three patrons of the 

 DeKalb factory was 3.83 ; in that from sixty patrons of the Malta factory, 

 3.70; and in that from sixty one patrons of the Shabbona factory, 3.G6. 

 The average of fat as sho.wn by 101 tests made of 35,017 pounds of milk 

 furnished by these one hundred and eighty-four patrons was 3.73 per 

 cent, showing that in large quantities of milk the tendency is to ap- 

 proach the average composition. 



Milk of different coics of the same herd. — In the milk of a herd of sixty- 

 four cows which " had been selected and bred with more than average 

 intelligence, the average per cent of fat found was 4.21 ; the high- 

 est, 5.85; the lowest, 2.75 — a variation of 3.10 i)er cent. The average 

 often cows was 5.41; often others, 3.2. Dividing the herd into four 

 equal lots, the average of one lot of sixteen was 5.18; of another lot of 

 the same number, 3.38." 



Milk from different breeds. — Analyses were made by the chemist of 

 this station of milk from prize cows competing at the Chicago Stock and 

 Dairy Show in 1889. The milk of three Holsteius averaged 3.17 per 

 cent of fat ; of two Ayrshires, 4.04 per cent, and of three Jerseys, 5.26 

 per cent. The first prize was awarded to a Holsteiu cow, giving in one 

 day 65 pounds 7 ounces of milk, containing 3.45 per cent of fat. 



The analyses illustrate anew and in a striking manner the importance 

 of testing the milk of individual cows in a herd. They also emphasize 

 the facts that the variation in milk of different cows may be greater 

 than that of different lierds, and that the larger the herd the greater is 

 the tendency of the mixed milk to approach the average composition. 



Composition of butter. — While chemical analysis can not determine 

 with certainty the comparative excellence of two samples of butter, the 

 determination of the composition of what is considered good butter in 

 American markets is of interest. " By co-operation of the Illinois State 

 Board of Agriculture and the Association of American Agricultural 

 Colleges and Experiment Stations, five samples were taken by Drs. 

 Babcock and Manns, chemists of the Wisconsin and Illinois Experi- 

 ment Stations, from each of nine lots of butter to which first prizes had 

 been awarded, in as many classes, at the American Dairy Show, held in 

 Chicago, in is^ovember, 1889, under the auspices of the Illinois State 

 Board of Agriculture." Samples were analyzed by five chemists, of 

 whom Dr. Manns was one. The report of the comiiiittee of the Asso 

 elation of Colleges and Stations is printed in this bulletin. The prize 

 samples averaged 85.74 per cent of fat, 10.23 per cent of water, 3.05 per 

 cent of ash, and 0.9G per cent of curd. An analysis of creamery butter 

 from Connecticut by E. H. Farrington, assistant chemist of the station, 

 is also given. 



3Iil]c tests: Determination of percentages of fat. — The use of cream 

 tubes and optical methods in determining the fat in milk are discussed 

 and the sources of error pointed out. Short's method and the lacto- 



