CHEMISTRY. 611 



remained clear at 40 to 50°; coutainiug- 1.5 gm. or more, at GO'^; and 4 

 gm. or more, at 70 to 80°. Duplicate determinations of phosphoric 

 acid in steel with niolybdic solutions containing G gm. tartaric acid per 

 100 cc. gave closely concordant results. The tartaric acid was suc- 

 cessfullj^ used to prevent the precipitation of niolybdic acid and iron 

 oxid on warming. 



Contribution to milk analysis, E. Beckmann {Milch Zf{j., 23 

 {189-1), No. 14, pp. 702, 703). — Fat determination. — The author proposes 

 to determine the fat as follows: 25 cc. of milk is placed in a stoppered 

 glass cylinder with an equal volume of water, 2.5 cc. of standard 

 acetate of lead added (5 cc. if milk is sour), shaken, and then suffi- 

 cient sodium bicarbonate to separate the serum. The serum is then 

 filtered off, the precipitate returned to the cylinder, mixed with glass 

 pearls or bits of glass rods, and sliaken with ether (3 or 4 times with 

 20 cc. each). The hlter is also placed in a separate cylinder and shaken 

 with ether. The ether layer is then poured oft' from the precipitate, 

 the ether evaporated, and the fat weighed. The method is claimed to 

 be equally safe for wliole or skim millv, sweet or sour, and to require 

 only 20 minutes. In G comparisons of tlie metjiod with Soxhlet's aero- 

 metric method by different i)ersons the largest dift'erence was 0.07 per 

 cent of fat. 



Freezing point. — The author has found that the freezing point of whole 

 milk is 0.54 to 0.58° C. (average 0.554°) lower than that of water, and 

 that the depression of the freezing point below zero is iiroi)ortional to 

 the water added to the milk. He suggests this as a means of detecting 

 water. The addition of 10 per cent of water depresses the freezing- 

 point 0.055°, which is believed to be a sufficient difference for prac- 

 tical discrimination. 



Milk analysis, Lescoeue, (i^ey. Tnteniat. Falsi/., 8, p, 12; ahs. in 

 Gheni. Centbh, 1801, II, No. 19, p. 816).— To detect the addition of 

 water, a little pulverized rennet is added to the milk sample. This 

 coagulates the milk and the specific gravity of the serum is taken, 

 which may vary from 1.029 to 1.031, and tlio total solids of the serum 

 determined, which may vary from G7 to 71 gm. per liter. The addition 

 of 4 i)er cent of water is said to decrease the siiecific gravity at 15° C. 

 0.001 and the solids 2 gm. per liter. 



Examination of composite samples of milk, M. Weibull {Chem. 

 Zt(j., 18 {1894), iVo. 81, pp. I'j(i7, 15(is). — In previinis articles (E. S. E., G, 

 p. 189) the author has advocated the addition of anunonia to milk that 

 was sour or curdled in testing it for fat and specific gravity. He now 

 sets forth the application of this in testing composite samples by 

 mechanical or gravimetric methods. He refers to Farriugton's jn'opo- 

 sition to add powdered lye to soured samples (E. S. E., 3, p. 150), but 

 suggests that this would hardly be practicable where gravimetric 

 methods were to be followed. 

 13788— No. 7 3 



