406 EXPERIMENT STATION RECORD. 



The phosphoric acids, A. Holt and J. E. Myers {Jour. Chem. Soc. [London], 

 'J9 {1911), No. 581, pp. 38-'f-391). — "The following conclusions may be drawn 

 from the experiments described in this paper: Pyrophosphoi'ic acid is formed 

 as an intermediate compound during the hydration of metaphosphoric acid. 

 The rate of hydration does not accord with any simple order of reaction. 

 Meta and pyrophosphoric acids, when prepared by dehydrating the ortho 

 variety, give complex molecules in solution, but when prepared by decomposing 

 the corresponding lead salts, simpler molecules result." 



Colorimetric determination of phosphoric acid, J. Pouget and D. Chouchak 

 {Bui. Soc. Chim. France, -'/. .st/-., 9 {1911), No. 13, pp. 6Ji9, 650; abs. in Jour. 

 Soc. Chem. Indiis., 30 {1911), No. 15, p. 985). — In regard to this method, which 

 has already been noted (E. S. R.. 21, p. 105). the authors i>oint out that the 

 acid sodium molj'bdate of commerce should be employed, and not the normal 

 salt. In order to obtain the right composition of the reagent they recommend 

 the following method for preparing it : 



" Two solutions, A and B, are prepared, A by dissolving 95 gm. of molybdic 

 acid and 30 gm. of dry sodium carbonate in 500 to 600 cc. of hot water, cool- 

 ing, adding 200 cc. of pure nitric acid of 36 per cent, filtering and making up 

 to 1 liter, and B by dissolving 2 gm. of neutral sulphate of strychnin in 90 cc. 

 of hot water, cooling and diluting to 100 cc. One cc. of B is mixed with 10 cc. 

 of A shortly before use, and the mixture filtered. To obtain a maximum of 

 accuracy with the method, 2 tests should be carried out with 0.2 and 0.3 mg. 

 of phosphoric acid respectively, to serve us standai'ds. the one most resembling 

 in tint the actual experimental solution being used for the colorimetric com- 

 parison." Standard solutions of phosphoric acid are prepared from monopotas- 

 sium phosphate. 



Determination of phosphoric acid by Neumann's method, I. Bang 

 {Biochem. Ztschr., 32 {1911), No. 5-6, pp. JfJ^S, Jfl't)-— The method was modi- 

 fied as follows : 



Precipitate the phosphoric acid in the usual manner with ammonium 

 molybdate, wash the precipitate, and then treat it with water and a definite 

 quantity of semi-normal potassium hydx'ate solution until it is dissolved. Fifty 

 cc. of formaldehyde solution, to which has been previously added from 5 to 6 

 drops of phenolphthalein and titrated until a slight red tint is produced, is then 

 added. The solution is then titrated with half-normal sulphuric or hydro- 

 chloric acid until the solution is colorless, and then with alkali to a distinct 

 red coloration. 



The titration of alkali carbonates beside hydroxids or bicarbonates, J. 

 TiLLMANS and O. Heublein (Ztschr. Angew. Chem. 2-'f {1911), No. 19, pp. 

 874-876). — Alkali carbonates can be accurately titrated with acid in a solution 

 containing hydroxids or bicarbonates, using phenolphthalein and methyl orange 

 as the indicators. The titration against phenolphthalein, however, must be in 

 a closed flask in order to prevent the escape of carbon dioxid. An exact de- 

 termination of alkali carbonates in such solutions can also be made by deter- 

 mining the methyl orange alkalinity, and the amount of acid thus employed 

 is used as a basis for a second test with a new portion of the solution. The 

 carbon dioxid liberated in the latter test is titrated with sodium hydroxid 

 against phenolphthalein in a closed flask. The end reaction in the latter 

 method can be more easily noted. 



An improvement in the method for estimating humus in soils, J. B. 

 Rather {Jour. Indus, and Engin. Chem., 3 {1911), No. 9, pp. 660-662). — 

 Previously noted from another source (E. S. R., 25, p. 614). 



The determination of the amount of dissolved oxygen absorbed by sewage 

 eflluents containing nitrites, and of the amount of nitrite in sewage effluents 



