AGRICULTURAL CHEMISTRY — AGROTECHNY. 411 



Detection of nitric acid in v/atered fruit juices, R. Cohn {Ztschr. Offentl. 

 Chem., 17 (If)ll), ^o. J!), pp. 361-363; abs. in Analyst, 31 (1912), iS^o. 1,30, p. 

 21). — The method is as follows: Make 75 cc. of the juice alkaline with sodium 

 hydroxid, evaporate nearly to dryness, and extract the residue with alcohol at 

 a temperature of 40° C. The extraction is conducted for several minutes. If 

 the residue from the alcohol extract still has a sirupy appearance it must be re- 

 extracted with alcohol, and then taken up with 10 cc. of water and tested with 

 diphenylamin for nitric acid. No positive reaction was ever obtained with 

 authentic raspberry, currant, or cherry juices. Bilberry juice was found to 

 give a blue coloration with sulphuric acid alone, and therefore can not be tested 

 by this method. Nitron can be employed for this pui-pose. 



Methods for sugar analysis and allied determinations, A. Givkn (Pliilo- 

 (lelphia, 1912, pp. 75, figs. 8). — This is a description of methods for examining 

 sugar and sugar products. The official methods are included and some apparatus 

 used in the Bureau of Chemistry of this Department is pictured. 



Examination of lactose and the by-products of lactose manufacture, A. 

 Burr and F. M. Bereerich (Chem. Zig., 3.', (1911), A'o.s. 82, pp. 751, 752; 86, pp. 

 791,-796; 87, pp. 803, 80'/).— Previously noted from another source (E. S. R., 

 26, p. 313). 



The chemical and bacteriological methods for examining milk, G. Rfjujf 

 (Ztschr. Fleisch u. Mllvhhyg., 22 (1912), No. 5, pp. 1 .',2-1 J,8) .—Thin continuation 

 of work previously noted (E. S. R., 25, p. 207) deals entirely with bacteriological 

 methods. It includes some special methods for detecting and differentiating the 

 organisms involved in mastitis, pyogenic infections, and actinomycosis. 



What is the best test for judging the quality of milk? J. StapensjSa 

 (Tijdschr. Veearl.^enijk., 39 (1912), Xo. 6, pp. 231-260).— This is a study of the 

 various methods proposed for examining milk from the hygienic point of view. 



The catalase test is given first place for detecting milks which contain secre- 

 tions from animals affected with mastitis. If a milk yields a volume of gas 

 of 2 cc. or more within 3 hours, at a temperature of 37° C.±, the sample should 

 be tested by the Trommsdorff leucocyte method and its chlorin content deter- 

 mined. When necessary other tests, such as Schardinger's reaction and the 

 diastase test, may be employed in addition. The relation of the bacterial con- 

 tent of the milk to these reactions is also considered. 



Methods for determining iron in milk, F. E. Nottbohm and W. Weisswange 

 (Ztschr. Untersuch. NaJir. u. Gemissmtl., 23 (1912), No. 10, pp. 511,-523). — This 

 work, which was done in part with synthetic ash solutions, confirms the findings 

 of other's that the iron content of milk can not be determined in a hydrochloric 

 solution of the milk ash by the colorimetric method. 



On the basis of the results obtained the authors recommend the following 

 method for determining the iron content of milk : One hundred cc. of milk is 

 dried in 2 platinum dishes on the water bath, heated to from 150 to 180° C, 

 and ashed in a quartz muffle. The process is then completed over a microburner. 

 In order to remove the last traces of carbon the ash is rubbed up with water, 

 dried, and ashed again. The white ash is now mixed with iron-free hydrochloric 

 acid and evaporated to dryness, and this process is repeated. The ash is then 

 taken up with 40 cc. of ^-normal hydrochloric acid solution, transferred to an 

 Erlenmeyer flask and oxidized by the addition of a few drops of nitric acid. 



A-fter cooling the ash solution it is transferred to a separatory funnel, 2 cc. 

 of a 5 per cent solution of " cujiferron " added, mixed well, and allowed to stand 

 for I hour. The solution is shaken out twice with 25 cc. of chloroform, the 

 chloroform exti-acts are transferred to a 100 cc, Erlenmeyer-Jena flask, and the 

 chloroform distilled off on a water bath, care being taken to distill off the last 



