16 EXPERIMENT STATION RECOED. [Vol.36 



The detection of natural and artificial pigments in oleomargarine and 

 butter, L. S. Palmer and W. E. Thrun (Jour. Indus, and Engin. Chem., 8 

 {1916), No. 7, pp. 614-618). — Because of the oleomargarine laws of many States 

 it has been found necessary to detect the presence of carotin (the natural 

 yellow pigment of animal fat) in this product. The authors have shown Cor- 

 nelison's test (E. S. R., 20, p. 910) to be A^Tongly quoted by Leach (E. S. R., 

 29, p. 204). The relation between Martin's test^ for artificial pigments in fat 

 and Moore's test^ for carotin added artificially to fat, as given in Leach's 

 Food Inspection and Analysis, is shown to be confused, and the true relation 

 is pointed out. Moore's test for carotin in fat or oleomargarine is specific not 

 alone for carotin added artifically but is also for the carotin natural to animal 

 fats. In this test carotin is not dissolved out of the fat, but is merely decolorized 

 by the ferric chlorid added. The reaction involved is a reduction of the iron 

 and the simultaneous oxidation of the carotin. 



The possibility of determining whether carotin has been added to butter 

 fat or oleomargarine is discussed. 



Separation and estimation of polysulphids and thiosulphate in lime-sul- 

 phur solutions, S. D. Averitt (Jour. Indus, and Engin. Chem., 8 (1916), No. 7, 

 pp. 623-621). — The author, at the Kentucky Experiment Station, submits an- 

 alytical data obtained from a comparative study of the direct iodin titration 

 procedure of Harris (E. S. R., 25, p. 414), the method described by Thompson 

 and Whittier (E. S. R., 32, p. 410), and two modified procedures, both of which 

 are similar to the method of Harris, excepting that in the one tenth-normal 

 hydrochloric acid is used instead of iodin for the monosulphur equivalent titra- 

 tion and in the other no attention is paid to the monosulphur equivalent titra- 

 tion. 



" The experiments described and data presented in this paper afford new 

 proof that calcium polysulphid in solution can be quantitatively decomposed by 

 iodin solutions and thus eliminated from a solution containing thiosulphate, 

 preparatory to the accurate determination of the latter." 



The same result may be accomplished by means of dilute hydrochloric acid 

 and elimination of the hydrogen sulphid formed by boiling. Sodium nitro- 

 prussid can be used as an internal indicator to show the end point of the dis- 

 appearance of the sulphid in the titration with iodin. The accuracy of the 

 iodin-titration method of Harris is confirmed. 



A rapid and accurate procedure for weighing the precipitated sulphur in the 

 iodin and hydrochloric-acid titrations of a lime-sulphur solution is proposed. 



Sulphur fungicides, G. P. Gray (OU. Rpt. Sess. Internat. Cong. Vit., 1915, 

 pp. 160-17 Jf). — The author discusses the subject under the following topics: 

 Source of the world's supply of sulphur, refining methods, kinds of sulphur, use 

 of dry sulphur, soluble compounds of sulphur, decomposition of sulphlds and 

 thiosulphates after application to the foliage, the home preparation of some 

 sulphur fungicides, commercial preparations of the alkali polysulphids, and the 

 compatibility of the sulphur fungicides. 



Methods of preparation and relative value of Bordeaux mixtures, O. Butleb 

 (Off. Rpt. Scss. Internat. Cong. Yit., 1915. pp. 151-160). — This is a general re- 

 view of the subject, with some special reference to use on the grapevine. Some 

 experimental data on the effect of temperature, strength in cupric sulphate, and 

 ratio of CuSO* to CaO on the rate of deterioration of Bordeaux mixtures ; the 

 relative toxicity of neutral and alkaline Bordeaux mixtures to the spores of 

 Phytophthora infestans and Plasmopara viticola; the effect of the method of 

 mixing on the adhesiveness of Bordeaux mixture; and the relative rate of 



1 Analyst, 12 (1887), p. 70. 



* Analyst, 11 (1886), pp. 163, 164. 



