108 EXPERIMENT STATION EECOED. 



Apparatus for the extraction of fresh plants with boiling alcohol, E. Boub- 

 QUELOT and H. Herissey (Jour. Pharm. et Chim., 7. ser., 3 (1911), No. ^, pp. 

 145-149, fig. 1; abs. in Jour. Soe. Chem. Indus., 30 (1911), No. 5, p. 306, fig. 

 1). — An illustrated description of an apparatus for rapidly extracting fresh 

 plants with boiling alcohol. 



A very sensitive indicator, J. F. Sacheb (Chem. Ztg., S'f (1910), No. 134, 

 pp. 1192, 1193; abs. in Jour. Chem. Soc. [London], 98 (1910), No. 578, II, p. 

 1106). — The author makes use of an extract of radish skins in 96 per cent 

 alcohol (1 part by weight of skins to 1 part alcohol). If the solution is acid 

 to litmus paper it is carefully neutralized with seminormal potassium hydroxid 

 solution. With alkalis the indicator is green and with acid it is intensely red. 

 It is, according to the author, more sensitive than either methyl orange or 

 phenolphthalein, but like the latter it is sensitive to carbon dioxid. 



Estimation of nitrates, Clarens (Jour. Pharm. et Chim., 7. ser., 1 (1910), 

 No. 12, pp. 5S9-593; abs. in Jour. Chem. Soc. [London], 98 (1910), No. 574, II, 

 p. 752). — This method is based on the reduction of nitric acid by mercury or 

 powdered copper in the cold. The nitric oxid thus produced is measured. 



A simple method for detecting nitrites, Dan6 (Bui. Soc. Chim. France, 4- 

 ser., 9 (1911), No. 8, pp. 354, 355; abs. in Chem. Zentbl., 1911, I, No. 25, p. 

 1763). — The reagent consists of 0.02 gm. of synthetic indol in 150 cc. of 95 

 per cent alcohol. 



[Cooperative work on phosphoric acid and potash by the division of fer- 

 tilizer chemists of the American Chemical Society], J. E. Breckenridge et al. 

 (Jour. Indus, and Engin. Chem., 3 (1911), No. 2, pp. 118-120). — A description 

 of the methods used and the list and results of the analysts in the cooperative 

 work for 1910. 



Estimation of potassium, as potassium platinic-chlorid, H. Feesenius and 

 P. H. M. P. Brinton (Ztschr. Analyt. Chem., 50 (1911), No. 1, pp. 21-35; abs. 

 in Analyst, 36 (1911), No. 421, p. 178). — This is an amplification of work 

 previously noted (E. S. R., 25, p. 107). 



In regard to determining phosphoric acid, G. Jobgensen (Ztschr, Angew. 

 Chem., 24 (1911), No. 12, pp. 51,2-544).— ^ri a reply to von Lorenz (E. S. R., 25, 

 p. 107) the author gives the historical facts in regard to the introduction of his 

 method for determining phosphoric acid. 



A volumetric estimation of phosphoric acid, J. Rosin (Jour. Amer. Chem. 

 Soc, 33 (1911), No. 7, pp. 1099-1104) .—A\t\xon%h. the Holleman method (E. S. 

 R., 6, p. 15) according to the author, yields better results than either the 

 Perrot* ... or Lieberman methods^ . . . the figures obtained are far from 

 satisfactoi-y. The reaction which is supposed to take place is. according to the 

 author, incorrect and may be more closely represented by the equation 

 3Na2HPO*+6AgN03=2Ag3P04+6NaN03+H8PO«. This was confirmed by experi- 

 ment. 



" The method as finally adopted, and which has given good results, Is as fol- 

 lows: The solution of the phosphoric acid contained in a graduated (200 cc.) 

 flask is neutralized, if necessary, to phenolphthalein, with caustic soda free 

 from chlorid, an excess of tenth-normal silver nitrate added and the mixture 

 well shaken. Zinc oxid, or a suspension of it in water, is then added little by 

 little, shaking vigorously for 2 or 3 minutes after each addition and testing for 

 free acid each time by dropping in a very small piece of blue litnuis paper. 

 When the color of the litmus paper is no longer affected, the solution is made 



iJour. Soo. Chem. Indus., 7 (1888), p. 311. 

 2 Analyst, 34 (1909), p. 361. 



