CONVENTION OF OFFICIAL AGRICULTURAL CHEMISTS. 18') 



Obsei'vatious on the changes in the specific gravity of sweet milk by 

 Iveeping show that the variations were not nniform nor very great. 



Acomparison of the calcnlation of millv solids by Fleischmann's, Bab- 

 cock's, Hehner and Riclimond's, and Richmond's fornudas with gravi- 

 metric results is reported for 15 samples of m ilk. The Hehner and Rich- 

 mond formula gave results most closely agreeing with the gravimetric 

 determinations. The other formulas, especially Babcock's, gave results 

 which were too high. 



An account of examinations by C. H. D. Richmond of 75 samples of 

 milk in the lines suggested by the reporter on dairy products is embodied 

 in the report to the Association. 



Tests of 2 samples of milk are reported which show no loss of fat on 

 souring. In another case where milk was mixed with sand and allowed 

 to stand, the solids and fat decreased from day to day. This decrease 

 was less when asbestos was substituted for sand. 



A paper entitled " Does cream lose fat by keeping for a long time 

 with and without bichromate of potash"?" was presented by A. L. Win- 

 ton. Treated and untreated samples showed practically the same per- 

 centage of fat at the end of 3 months as at the beginning of the experi- 

 ment. 



A paper •' On the determination of the rise in specific gravity on allow- 

 ing milk to stand after milking," by 0. H. D. Richmond, was presented 

 to the convention. Very slight variations were observed in the specific 

 gravity of samples of milk determined at the end of 1, 6, 18, and 21: 

 hours after milking, although in previous observations by the author in 

 autumn and winter a distinct rise in specific gravity had always been 

 noticed. The results indicate that the slight variation observed could 

 not have been due to change in milk sugar. Salicylic acid appeared to 

 prevent variation. 



In a paper "On the determination of albumen in cows' milk,'' L. L. 

 Van Slyke described the following method: The filtrate from the casein 

 l)recipitate' is heated in a covered beaker in a boiling water bath for 

 10 to 15 minutes, filtered, the precipitate of albumen washed, removed 

 to the digestion fiask, and treated by the Kjeldahl method. In connec- 

 tion with this method, brief directions for determining the total nitrogen 

 compounds in milk, the casein, the albumen, and other nitrogen com- 

 pounds are given, and attention is called to tlie crude nomenclature of 

 the nitrogenous constituents of milk now in vogue. 



A method of determining the butter fat in milk and cream by difter- 

 ence was described in a paper by S. W. McKeown. The method is as 

 follows: Weigh out 2 gm. of the milk or cream in a crucible lid 1^ to 2 

 iii. in diameter, dry at 212° F., weigh, and immerse in l.">0 cc. of petroleum 

 naphtha in an upright ])Osition for 1 hour or more. Remove from the 

 solution, dry at 212'^ F. i'ov .'30 minutes, and weigh. The results agree 

 closely with those by the Adams method. 



' U. S. Dept. Agr., Div. of Chcm. Biil. 38, p. 109. 

 G210— No. 3 2 



