1918] AGRICULTURAL CHEMISTRY AGROTECHNY. 413 



or alizarin. To 50 cc. water extract of the flour, 2 cc. of an alcoholic sol-ution 

 of the dye is added, and the solution heated to boiling. If the flour is pure, a 

 white or cream-colored coagulum is formed from the soluble protein. The 

 presence of alum causes the formation of the color lake characteristic of the 

 dye used. 



Tables are given showing the characteristic colors with cochineal and alizarin 

 in the presence of different percentages of alum and also of zinc, copper, 

 and lead. 



Research on th.e detection of added water in milk, H. Durand and R. Stev- 

 enson {Jour. Indus, and Enr/in. Chem., 10 (1918), No. 1, pp. 26-30, fig. 1). — This 

 is a report of new methods for the detection of added water in milk proposed 

 in an earlier article (E. S. R., 36, p. 807). The first two methods were based 

 on the theory that water would increase the solubility of organic salts in the 

 serum of milk. In one case lead subacetate was used and in the second silver 

 nitrate. Both methods proved unrelial^le. The third method, the determina- 

 tion by the electrical conductivity method of Kohlrausch of the whole milk 

 and of the serum after coagulation with electrolytes and nonelectrolytes, was 

 tried out in an elaborate series of experiments but with no uniformity of results. 



One of the authors proposes to continue the research, making use of the 

 osmotic pressure of milk in a cell constructed to measure the differential 

 osmotic pressure between milk and a standard saline solution. 



The differentiation of coconut oil and palm-kernel oil in mixtures, G. D. 

 Elsdon (Analyst, Jt2 {1911), No. 498, pp. 298-300).— The author states that it is 

 possible to distinguish between coconut and palm-kernel oils in mixtures of 

 various fats, such as margarin, by obtaining both the Polenske and Shrewsbury- 

 Knapp values and assuming the presence of palm-kernel oil in those cases in 

 which the percentage of coconut oil calculated from the Polenske figure is less 

 than that from the Shrewsbury-Knapp figure. This may, however, indicate the 

 presence of coconut stearin which has practically the same composition as palm- 

 kernel oil. He emphasizes the importance of the Shrewsbury-Knapp process in 

 preventing incorrect conclusions being drawn from the Polenske process. 



A combined Reichert-Polenske and modified Shrewsbury-Knapp process, 

 G. D. Elsdon {Analyst, 42 (1917), No. 498, pp. 295-298, fig. i).— This article 

 gives the results of a combination of the modified Shrewsbury-Knapp process 

 previously noted (E. S. R., 37, p. 618) with the Reichert-Polenske process for the 

 estimation of coconut oil in mixtures. The process is carried out as follows : 



The flask containing the residual acids after the distillation of 110 cc. in the 

 Reichert-Polenske method is cooled in water until the acids have become a solid 

 cake. The cake is broken and the liquid strained through a fine wire sieve. 

 The fatty acids are washed with 50 cc. of cold water, drained, returned to the 

 flask, and dried in the oven. One hundred cc. of alcohol (sp. gr. 0.9200 at 

 60° F.) is then added and the process continued as given in the previous paper. 



The method is much more rapid than the Shrewsbury-Knapp process. The 

 results of analyses of various mixtures of coconut oil with butter and with 

 margarin are given in tabular form and also in the form of curves from which 

 the percentage of coconut oil in a given mixture may be read off. In using this 

 combined process on butters, high figures for alcohol-soluble acids are invariably 

 found in conjunction with high Reichert values. Consequently a high alcohol- 

 soluble acid figure with a low Reichert value would indicate the presence of 

 coconut oil while neither the Reichert nor the Polenske number alone would 

 cause suspicion. 



Variation in the ether extract of silag^e, L. D. Haigh (Jour. Indus, and 

 Engin. Chem., 10 (1918), No. 2, p. 127). — Analyses are reported showing the 



