314 EXPERIMENT STATION RECORD. 



milk out of a churn into another churn and bacli again 3 successive times, is a 

 good one. The plunger method with proper mixing may give good results. 



A new formula for the calculation of the per centum of added water in 

 cow's milk, F. J. Slataper (Bill. Tex. Bd. Health, 5 {1911), No. 9, pp. 17,18).— 

 A refractometric method of determining added water is given, which according 

 to the author is new. The refractometer reading is subtx-acted from 42.4 (the 

 figure for whole milk). This equals the number of degrees the reading is 

 lowered by the added water, and divided by 0.274 gives the percentage of added 

 water. 



The value of chemical constants for detecting watered milk, G. Cornalba 

 (Riv. Sci. Latte, 1 {1911), Nos. 2, pp. 45-52; 3, pp. 65-77). — Continuing pre- 

 vious work (E, S. R., 20, p. 419; 21, p. 614) the author again shows the value 

 of determining the soluble substances of milk serum (6 parts or thereabouts 

 per 100 of milk) for detecting the watering of milk. This is deemed better 

 than either the refraction or cryoscopic test. 



Detection of watered milk, Ledent {Bui. Soc. Chim. Belg., 25 {1911), No. 3, 

 pp. 133, 13-'t; ahs. in Jour. Soc. Chem. Indus., 30 {1911), No. 7, p. .}-'/^)-— The 

 Cornalba method (see above) yielded very satisfactory results for detecting 

 watered milk. 



The superficial tension of milk and milk adulteration, E. Carapelle and 

 G. Chimera {Rev. Hyg. et Med. Infant., 9 {1910), No. 2, pp. 167-178; ahs. vn 

 Rev. Sci. [Paris], 49 {1911), I, No. 1, p. 20; Ann. Falsif., 4 {1911), No. 29, p. 

 160). — ^According to these authors the superficial tension of milk (cow's, goat's, 

 and ass's) is greater in milks in which the cream has been removed or where 

 water has been added to the milk. 



The electrical conductivity of milk, R. Binaghi {Biocliem. Ztschr., 29 

 {1910). No. 1-3, pp. 60-79).— Noted from another source (E. S. R., 25, p. 207). 



The alcohol test and the acidity of milk, G. Fendler and C. Borkel {Ztschr. 

 Vntersuch. Nahr. u. Genussnitl., 21 {1911), No. 8, pp. 477-Jf80; ahs. in Jour. 

 Soc. Chem. Indus., 30 {1911), No. 10, p. 643) . — ^This test, which has been pro- 

 posed for ascertaining the freshness of milk, consists of mixing milk with 

 twice its volume of alcohol (50 per cent by volume). It is claimed that if the 

 milk is fresh it will not curdle, and, therefore, its acidity is not more than 8 

 Soxhlet degrees. When the acidity is higher, coagulation takes place. 



As a result of examining many hundred samples of milk the authors declare 

 that while the test may serve as a preliminary one no definite relation seems to 

 exist between the acidity of milk and the results obtained with the alcohol test. 



Determination of iron by the colorimetric method (cow's milk), H. Lachs 

 and H. Friedenthal {Biochem. Ztschr., 32 {1911), No. 2, pp. 130-136) .—This 

 procedure is based on the fact that the blood-red coloration which is caused by 

 the union of iron and sulphocyanogen is produced by the undissociated iron 

 sulphocyanate (ferric sulphocyanid) and reaches its greatest intensity in the 

 presence of an excess of sulphocyanogen at a definite hydrogen ion concentra- 

 tion. Iron sulphocyanate can be extracted from the solution with ether. 



The procedure is as follows: Five cc. of cow's milk are dried and ashed in a 

 deep platinum crucible. The ash is dissolved in 1 cc. of a 6 times normal 

 hydrochloric acid standard solution and 1 cc. of water. To the solution is 

 added 1 cc. of a concentrated solution of potassium sulphocyanate and the 

 mixture shaken up with 1 cc. of ether. The mixture after separation is com- 

 pared as regards color with standard solutions of iron sulphocyanate in ether. 

 With this method a milk sample was found to contain 1.3 mg. of iron per 

 liter, and a comparative test with the same milk but with 500 cc. for ashing 

 gave 1.4 mg. per liter. The test is affected by trichloracetic, sulpho-salicylic. 



