14 EXPERIMENT STATION RECORD. [Vol.43 



The iddiii wliicli has been absorbed in potassium iodld may be titrated with 

 tbiosulphate and tlie results cliecked witli tliose obtained by the permanganate 

 niciliod. The results ol)taiiied with permanganate are, however, uniformly 

 higher and are considered more accurate. While the results for bromid are 

 also low, the metlwxl outlined is considered to give more accurate results than 

 any oilier metiiod for the bromid content of such mixtures. 



The quantitative microanalysis of foods and feeding stuffs, W. Hekter 

 (Ztsclir. rnlersuch. Kahi: ii. Gcnusstntl., 38 (1919), No. 3-^, pp. 65-89, figs. 

 JO). —This is a description t)f the author's method for the quantitative micro- 

 analysis of starch-containing food materials and feeding stuffs,' together with 

 a discussion of the scope and reliability of the method. 



Determination of lactose in altered milk, E. Hildt (Ann. Chim. Analijt.. 2. 

 SCT-., 2 (1920), No. 2, pp. 43-.'f6). — It is pointed out that samples of milk pre- 

 served with l)ichromate alter more or less in composition depending upon the 

 season, and that this alteration is shown particularly in the content of lactose, 

 which on standing undergoes partial hydrolysis. To determine the extent of 

 this alteration the author proposes a series of calculations involving the use 

 of factors consisting of the reducing power of definite quantities of hyd rated, 

 anhydrous, and hydrolyzed lactose. In hydrolyzing the lactose, benzene-sul- 

 phonic acid was used as a catalyzer as previously recommended (E. S. R., 40, 

 p. 507). 



Rapid method of estimating lead in cassia oil, O. F. Lubatti (.Tour. Sac. 

 Chcm. Indus., 39 {1920), No. 3, pp. 35T, 36T, fig. 1).—In the method described 

 the lead is estimated colorimetrically as follows: 



Five cc. of the cassia oil is diluted to 20 cc. with 70 per cent alcohol, and 5 

 or 2.5 cc. of this solution (depending upon the estimated lead content) is 

 pipetted into a 50 cc. Nessler tube of 2.5 cm. diameter and diluted to about 20 

 cc. with 90 per cent alcohol. A blank from lead-free cassia oil is similarly pre- 

 pared, and to each of the tubes is added 1 cc. of ammonium sulphid solution. 

 To the blank is then added, with thorough stirring, a standard lead solution in 

 90 per cent alcohol (1 cc=0.0001 gm. of lead) until the color of the blank 

 matches that of the sample when compared in the Duboscq colorimeter or a 

 similar device. A special colorimeter devised by the author is described and 

 illustrated. 



The results obtained witli commercial samples of cassia oil by this method 

 and by the gravimetric procedure of extracting the lead with dilute nitric acid 

 and precipitating as lead sulphate showed a close agreement, although the re- 

 sults obtained by the new method were slightly lower. Determinations of the 

 lead-dissolving jiower of cassia oil indicated that the amount of lead absorbed 

 increased with time to a maximum value of 0.074 after one month. The 

 amount of lead in commercial samples as a result of the use of lead containers 

 averaged from 0.04 to 0.06 per cent. 



Problems investigated at the color laboratory, Bureau of Chemistry, 

 H. D. GiBBS {Chein. and MetoUnrg. Engin., 22 (1920), No. 9, pp. 405-407, figs. 

 2). — The author discusses briefly some of the problems which have been or are 

 being investigated at the color laboratory of the Bureau of Chemistry, U. S. 

 Department of Agriculture. These include the production of photographic 

 sensitizing dyes; vapor phase chlorination. oxidation, and sulphonation ; and 

 various chemical problems undertaken for the Air Service during the war. 



A previous statement of the objects and problems of the color laboratory has 

 been noted from another source (E. S. R., 40, p. 16). 



> W. Herter and W. Rasch, Ztschr. Gosam. Getreidew., 6 (1914), No. 10-11, pp. 210, 

 211; 7 (li»15), No. 1'. pp. 30-42. 



