22 Journal of Agrictdtural Research voi. xvu. No. i 



representative total peld of milk. The milk samples for the analysis 

 were obtained as follows: After the 24-hour period was concluded for 

 the total >neld of milk the lamb was kept away from the ewe until a 

 sufficient quantity of milk was in the udder; then the lamb '..^as allowed 

 to suckle one side, while the other was milked dry. In this manner a 

 uniform sample was obtained without causing undue nervousness on the 

 part of the ewe. 



CONSTITUENTS DETERMINED IN THE MILK 



The samples of milk were analyzed for the following constituents: 

 Total nitrogen, casein, albumin, fat, lactose, specific gravity, and ash. 

 The ash was then analyzed for the calcium and phosphorus content. 



METHODS USED 



Total nitrogen. — A quantity of milk (approximately 5 gm.) was weighed accu- 

 rately and the nitrogen determined by the Kjeldahl method. 



Casein. — Casein was precipitated by acetic acid on a weighed quantity of milk 

 according to the official method. The nitrogen deuermined by the Kjeldahl method 

 and the results multiplied by tlie factor 6.38. 



Albumin. — After neutralizing the filtrate obtained after removing the casein, with 

 sodium hydroxid, and adding acetic acid of the proper strength and quantity, accord- 

 ing to the official methods,' the nitrogen was determined by the Kjeldahl method 

 and the result multiplied by 6.38. 



Nonprotein nitrogen. — The sum of the nitrogen of the casein and albimiin was 

 subtracted from the total nitrogen. The result gave the nonprotein nitrogen. 



Fat. — The fat was determined by the Babcock method. 



Lactose. — A portion of milk (approximately 10 gm.) was weighed accurately 

 in a flask and 25 cc. of distilled water were added. The proteins were precipitated 

 with a sufficient quantity of colloidal ferric hydroxid as described b)^ Hill.- They 

 were then filtered off and the clear filtrate collected in a volumetric flask. The 

 proteins were washed ^vith distilled water until free from lactose. The combined 

 filtrate and washings were made up to a definite volume and the lactose determined 

 by the volumetric method of Benedict.* The colloidal ferric hydroxid proved to 

 be a very efficacious clarifier, as it is very simple to use and insures thorough clarifi- 

 cation and a clear solution. 



Specific GRA\^TY. — Specific gravity was determined by the Westphal balance. 



Ash. — The ash was made upon composite samples of the four samples of milk by 

 the official methods. 



Calcium and phosphorus. — Calcium and phosphorus were determined from the 

 ash residues by the methods described by Richmond.* 



DISCUSSION OF RESULTS 



In Table I is found the percentage composition and total yield of 

 roiik of each ewe for the entire series taken every 10 days during a 

 period of 24 hours. In all cases the first results upon the total weight 



'Association of Opfioai. Agricctltdrai, Chemists, peport op committee on' editino methods 

 OP ANALYSIS, p. 287-Z89. Baltimore, Md., 1916. (Jour. Assoc. Off. Agr. Chem., v. 2, no. 3, pt. 2.) 



- Hni,, Reuben L. note on the use op colloidai, iron in the determination op lactose in 

 MTLK. /rt Jour. Biol. Chem., V. JO, no. 3, p. 175. 176. 1915. 



' Benedict, Stanley R. the detection and estimation of glucose in itrine. In Jour. .\mer. 

 Mtd. Assoc., V. 57, no. 15, p. 1193-1194. 1911. 



^ Richmond, Henry Droop, dairy chemistry, p. 8i-8a. London. iS<^. 



