208 EXPERIMENT STATION RECORD. 



Las a constant electrical conductivity. When the milk is watered tlie elcc- 

 ti-ical conductivity diminishes. Sodium bicarbonate, sodium carbonate, borax, 

 and boracic acid increase tbe conductivity, and in proportion to the amount of 

 electrolytes added. 



The method is described as easy and rapid of execution. The constants 

 established for 30 samples of milk were the following: Sheep's, 49.43 to 51.72 

 (average K25=r)0.40X10— ') ; goat's, 47.01 to 49.96 (average K25=49X10— ') ; 

 cow's, 47.97 to 49.78 (average K25=48.70X10— '). 



Table for obtaining the specific gravity of milk from the milk-ammonia 



mixture, W. D, Kooper { Milch lo. Zcnihl., 6 (1910), No. 12, pp. 5)0 -5. ',3). —The 



specific gravity of curdled milk is determined by adding a definite amount of 



ammonium hydrate and determining the specific gravity of the liquid. The spe- 



„ (M+A) • S'— A-S" 

 eific gravity of the original milk is found by the formula S= ^ , 



where S is the specific gravity of the milk, S' the specific gravity of the milk- 

 ammonia mixture, S" the specific gravity of the ammonia, M the volume of 

 milk in cubic centimeters, and A the volume of ammonia in cubic centimeters. 



A table is appended for shortening some of the calculations involved. See. 

 also a previous note (E. S. R., 2.3, p. 308). 



Testing for the calcium sucrate in sterilized milk and cream, W. EiCH- 

 HOLz {Blilcliw. ZentU., 6 (1910), No. 12, pp. 536, 537).— The author believes the 

 best method to be the determination of the so-called lime residue figure, 

 because tlie Cotton number as modified by Baier and Neumann (E. S. R., 21, 

 p. 12) is unreliable. 



Determination of fat in cheese by the hydrochloric acid method, H. Hoft 

 (Clicm. Ztg., 3-'i {1910), No. 150, pp. 13'i3, iS'/'/).— The comparative results 

 obtained in these tests show that neither the concentration of the acid used, 

 nor whether alcohol was employed or not, had any influence on^ the ultimate 

 results. The cheeses examined were Tilsiter, Gouda, Edam, Camembert, Lim- 

 burger, Romadour, and Wilstermarsch. See also previous notes (E. S. R., 6, 

 pp. 15, 109; 16, p. 440; 24, p. 14). 



The determination of sucrose in beet-sugar factory products by Clerget's 

 process, using invertase as hydrolyst, .7. P. Ogilvie {Jour. Soc. Cheni. Indus., 

 SO {1911), No. 2, pp. 62-64). — After discussing the various sources of error 

 with the method, particularly when the saccharine substance is improperly def- 

 ecated, the author concludes that "if in determining the sucrose in beet 

 molasses by Clerget's process invertase be used as hydrolyst, distinctly higher 

 results are then obtained than with the ordinary Herzfeld modification in which 

 concentrated hydrochloric acid is used as hydrolyst. But if in operating the 

 Herzfeld process the error due to the influence of the optically active non sugar 

 substances be obviated by using the direct acid polarization instead of the usual 

 alkaline (basic lead acetate) polarization, then the results do not differ ap- 

 preciably from those obtained by means of invertase. From this the fact would 

 appear to be established that invertase is a selective hydrolyst, inverting only 

 the sucrose' (and raffinose also, if present), without at all affecting the non- 

 sugar bodies. 



" The Pellet method of obviating the erior due to the influence of the optic- 

 ally active nonsugars, by taking the direct polarization in a solution made acid 

 by sulphui'ous acid, gives the same results as the method proposed by Andrlik 

 and Stanek in which the concentrated hydrochloric acid and urea are used, be- 

 sides having certain other apparent advantages. As a practical method, Pel- 

 let's sulphurous process is now recommended as preferable to the Andrlik and 

 Stanck procedure, by reason of its greater ease of manipulation and several 

 other apparent advantages." 



