112 EXPEEIMENT STATIOF EECOED. [Vol. 85 



The determination of the iodin number of essential oils, R. Mabcille (Ann. 

 Falsif., 9 {1916), No. 87, pp. 6-11, figs. 2).— Experimental data as to the iodin 

 numbers of various essential oils and oils used as adulterants, together with 

 their refractive indexes, are submitted in tabular form. The effect of light on 

 the iodin absorption vpas studied and the results are expressed graphically. 



The iodin value of the oils in liqueurs can be determined without first distilling 

 the alcohol, and is a valuable method for detecting adulteration in such 

 products. 



The detection and determination of benzoic acid in animal foodstuffs, K. 

 Baumann and J. Geossfeld {Ztschr. Untersuch. Nahr. u. Genussmtl, 29 {1915), 

 No. 10. pp. 897-409). — After reviewing the methods commonly used for the detec- 

 tion and determination of benzoic acid the authors outline a procedure for 

 which they claim excellent results. This, method consists essentially of con- 

 verting any free benzoic acid in the material to the alkali salt by treatment 

 with dilute alkali, precipitation of the alkali soaps thus formed with calcium 

 chlorid, precipitation of the protein with phosphotungstic acid, extraction 

 of the benzoic acid from the clear filtrate, and, finally, determining the acid 

 either colorimetrically or by titration with standard alkali. Carbon tetra- 

 chlorid was found to yield excellent results as an extraction agent. 



Experimental data obtained from the application of the method to the de- 

 termination of benzoic acid in milk, lard, butter, margarin, and cacao fat are 

 submitted which indicate the accuracy of the method. 



Critical observations on the qualitative and quantitative determination of 

 saccharin and a new procedure for its qualitative determination, M. Klostee- 

 MANN and K. Scholta {Ztschr. Untersuch. Nahr. u. Genussmtl., 31 {1916), No. 

 S, pp. 67-78). — Earlier methods used for the determination of saccharin are 

 briefly reviewed. A proposed procedure is described in detail and the theory 

 of the reaction discussed. The reaction is sensitive to 1 mg. of saccharin and 

 is more specific than the others commonly used. 



The quantitative determiration of urea, C. P. Mom {Chem. Weekbl., IS 

 {1916), No. S, pp. 72-75).— A method for the determination of urea in urine, 

 using TJrobacillus pasteurii, is described. The urea-splitting power of the soy 

 bean is not attributed to the presence of a urease, but rather to bacterial 

 action. 



The chemical composition and evaluation of lime-sulphur solutions, J. 

 Bodnar {Chem. Ztg., 39 {1915), No. lU, pp. 715, 716).— The author contends 

 that lime-sulphur solutions contain no soluble sulphite and that the use of the 

 term " sulphite+sulphate " in the evaluation of such solutions is incorrect 

 and should be replaced by the word " sulphate." Experimental data are sub- 

 mitted in support of this contention. 



A new procedure for the evaluation, based on the following equations, Is 

 described : 



CaS4-f-2AgN03=Ag=S + S3+Ca(NOs)« 

 CaSB+2AgN03=Ag=S + S«+Ca(NOs). 

 CaS203+2AgNO,= Ag2S203+Ca(NOa)» 

 AgjSjOa+HjO^AgjS+H^SO* 



Briefly the procedure consists of diluting 10 cc. of the original solution to 100 

 cc. and designating this as solution A. To 50 cc. of tenth-normal silver nitrate 

 diluted to 70 cc. 10 cc. of solution A is added, with constant agitation which 

 facilitates the clumping of the precipitate and produces a clear supernatant 

 Uquld. After diluting the mixture to 100 cc. it is filtered by suction through 

 a Gooch crucible into a dry suction flask. The precipitate is thoroughly 



