336 EXPERIMENT STATION RECORD. 



eessively with dilute hydrochloric acid, alcohol, ether, and water, and drying. The 

 weight of the sponge then remains practically constant, the maximum loss in the 

 subsequent operations being placed at 1 mg. The piece of sponge is weighed, mois- 

 tened with distilled water, and made to absorb 5 cc. of milk. It is then dried at 80° 

 C. to a constant weight, 3 hours being generally sufficient, 



The total solids are then ascertained by loss in weight. The fat is then extracted 

 in a Soxhlet apparatus and also determined by the loss in weight, The sponge con- 

 taining the solids-not-fat is then subjected to fumigation with formaldehyde gas to 

 render the proteids insoluble, and is then thoroughly washed with 50 per cent alcohol 

 containing 5 per cent acetic acid and with distilled water to remove the milk sugar 

 and mineral matter. The sponge is then dried and weighed, the loss in weight rep- 

 resenting the proteids and also about 2 mg. of ash for an original sample of 5 <•<•. of 

 milk. Ash is determined on a separate sample and milk sugar calculated by 

 difference. 



Analyses by the method described are given of 7 samples of cow's milk and a num- 

 ber of samples of human milk from normal and diseased subjects. 



Chemical analysis and cryoscopy of milk, H. Lajoux (Ann. Chim. Ahalyt., 

 10 {1905), No. 6, pp. 219-231). — Cryoscopic determinations were made on 24 samples 

 in the municipal laboratory at Reims. 



The freezing point averaged about —0.55° C. and was apparently not influenced 

 by the kind of food, the breed of cows, nor the density and fat content of the milk. 

 The freezing point is, however, affected by the addition of water, and it is for the 

 detection of this that the method is considered a valuable supplement to chemical 

 analysis. For market milk a legal standard of —0.55 to —0.57° is suggested. For 

 individual cows the freezing point may exceptionally be —0.54°. A freezing point 

 between —0.55 and 0° would, therefore, serve to indicate approximately the propor- 

 tion of water added, bearing in mind, however, that pathological conditions of the 

 milk or the addition of soda or other substances may affect the reading. 



The Sichler "sin-acid" butyrometry, W. Schneider (Client. Ztg., 29 (1905), 

 No. 51, p. 690). — Comparative tests of the Gerber and Sichler methods were made on 

 goat's milk and cow's milk during a period of 6 months. In its present form the 

 Sichler method is not considered equal to the Gerber method. 



Sulphuric acid for the determination of milk fat by the Gerber method, 

 M. Siegfeld (Molk. Ztg., 19 (1905), No. 29, p. 7S8).— While pure acid is not neces- 

 sary for this purpose, badly contaminated acid was found to be very unsatisfactory. 



The estimation of fat, L. Liebermann (Arch. Physiol. \_Pfluger~], 108 (1905), No. 

 10-12, pp. 481-488). — According to the author, simple extraction with alcohol and 

 ether does not give results w T hich are comparable with the saponification method, 

 unless the alcohol extraction is continued for days. Indeed, a complete extraction 

 of the fat is hardly possible. 



The estimation of fat in infant and invalid foods, C. B. Cochran (Jour. Amer. 

 Chem. Soc, 27 (1905), No. 7, pp. 906-909). — The method proposed consists in treat- 

 ing the sample of milk or milk products under suitable conditions with equal vol- 

 umes of 80 per cent acetic acid and concentrated sulphuric acid, warming until the 

 substance turns a coffee color, cooling, mixing with a small amount of ether, and heat- 

 ing with hot water until the ether vapor is removed. The layer of supernatant fat 

 can then be measured and the proportion of fat calculated from the amount of mate- 

 rial used. 



The use of the centrifuge in the analysis of cocoa and chocolate, F. Bordas 

 and Touplain (Rev. Soc. Sci. Hyg. Atiment., 2(1905), No. 1, pp. 92-110). —Methods 

 of analyzing cocoa and chocolate are described and analyses reported. The use of a 

 centrifugal machine for determining fat and materials insoluble in water and insolu- 

 ble in a mixture of water, alcohol, and ether is recommended. According to parallel 

 determinations, the centrifugal method for determining fat (ether, carbon disulphid, 



