DAIRY FARMING DAIRYING AGROTECHNY. 173 



"(e) For farrow cows when their condition does not follow abortion: any 

 combination of the fourth or fifth month's test with that of either the thirteenth 

 (•r foiu'teenth month linked with that of any month from the seventh to the 

 eleventh inclusive. The outcome is likely to be within 0..'>0 per cent fat of the 

 truth seven times in eight. 



•' In each case add the results and divide by the number of tests, two or three 

 as the case may be, for calculated average test for the year." 



The bulletin contains the summarized data and discussions upon which the 

 above conclusions are based and also gives suggestions concerning weighing, 

 sampling, and testing milk. 



Milk yield and breast girth, E. Schnabel {Milch. ZUj., 36 {1901), \o. ,?6, 

 pp. SO.'i, 303). — A maximum yield of milk was associated with a maximum breast 

 measure in 27 out of 40 comparisons and with a minimum circumference in 8 

 comparisons. Five comparative tests sh«)\'\ed no difference. 



Report of the dairy institute at Hameln, 1906, P. Vieth {Bcr. Mllcliir. 

 I list. Ha Did n, 1906, pp. 39). — The results of the various lines of work are briefly 

 summarized and determinations of the fat content of the milk of 346 herds 

 and comparative determinations of the fat in milk by the Gottlieb and Gerber 

 methods are reported in full. 



The action of dilute acids upon casein when no soluble compounds are 

 formed, L. L. and U. D. Van Slyke {Xeiv York >Sfatc Sfo. Tech. Bill. 3, pp. 7J- 

 1-J3. fii/s. l'>). — The authors started out to determine the amount of acid which 

 would combine with casein to form a definite compound insoluble in water, but 

 failing to find a simple chemical combination they investigated the behavior of 

 casein when brought into contact with different acids. The general scope of the 

 work and the jtrincipal conclusions reached are summarized by the authors as 

 follows : 



"The behavior of casein was -studied (1) with four acids of different, dissoci- 

 ating power (hydrochloric, sulphuric, lactic, and acetic) ; (2) with N-12.5, X-.500, 

 N-1000, and X-2()00 concentrations of these acids; (3) for contact of different 

 periods of time, ranging from 5 minutes to 48 hours; (4) at different tempera- 

 tures (U°, 2.j°, and 4.j° C. ) ; and (.")) with dilute solutions of neutral salts 

 (potassium chlorid and magnesiiun sulphate). . . . 



" It was necessary first to ascertain conditions under which casein forms 

 soluble compounds with dilute acids in order to avoid such solution. Evidence 

 of solution was shown (1) by viscosity of solution, (2) by l)ehavinr of solution 

 on adding alkali, such as opalescent or milky appearance or precipitation, (3) 

 by the xanthoproteic reaction, and (4) by deviation between results obtained 

 by condvictivity and by titration methods. In case of solution, titration results 

 are untrustworthy for measuring the amount of free acid in solution because 

 the dissolved proteid neutralizes per se part of the alkali used for titration, 

 and also gives up to the alkali any acid with which the proteid may have coni- 

 l)ined. Little or no solution of casein occurs even on several hours' contact 

 at 0° ('. with solutions not stronger than N-500, or at 2.5° V. with solutions not 

 stronger than X-IOOO. Degree of solution is increased (a) by concentration of 

 acid, {h) by increase cf temperature, and (c) by prolongation of contact. The 

 solvent action of the four acids studied was in the following order, from 

 strongest to weakest: Ilydroc-hloric, lactic, sulphuric, and acetic. The rate at 

 which casein dissolves in different acids of the same normality is not propor- 

 tional to tlie concentx'ation of the 11+ ion., or to the dissociation, but is dis- 

 proportionately great for the weak organic acids. From solutions of e(iual 

 strength, the dis'solved proteid takes up a larger proportion of acid than <loes 

 tlie undissolved. . . . 



