AGRICULTURAL CHEMISTRY AGROTECHNY. 503 



"In a test tube (15 by 150 mm.) place 1 cc. of urine and 1 cc. of strong 

 sulphuric acid and boil until frothing ceases, being careful not to allow any of 

 the froth to leave the tube. Cool and add 0.5 gm. potassium sulphate and again 

 boil until solution becomes nearly or quite colorless. Cool and then make 

 up contents of tube to 5 cc. with water. Again allow to cool and then fill the 

 small arm of the Hiuds-Doremus ureometer with it, the large arm of the instru- 

 ment being filled with sodium hypobromite .solution. The usual manipulations 

 for a urea estimation are now carried out, allowing, however, 2 cc. of the 

 acid solution to run into the hypobromite. The number of divisions occupied 

 by the evolved gas is observetl and then multiplied by 0.373, the result being 

 the number of cubic centimeters of nitrogen. Correct this volume for tempera- 

 ture and pressure and multiply the result by 0.00125, the final result being 

 the weight in grams of total nitrogen in 0.4 cc. of urine." 



The time required for the operation should not exceed 30 minutes. 



A new volumetric estimation of nitrites and separation of nitrous and 

 nitric acids, \V. M. Fischer and N. Steinbach {Ztsclrr. Anorgan. Chem., 78 

 (1912), No. 1, pp. l.U-l^Of; ahs. in Jour. Chem. Soc. [London], 102 {1912), No. 

 601, II, pp. 1093, 1094). — "There is no satisfactory method for the estimation 

 of nitric acid in the presence of nitrous acid. A method is provided by the 

 rapid esterifieation of nitrous acid in which oxidation to nitric acid does not 

 take place, as is proved by experiments with pure silver nitrite. The solution 

 is placed in a 300 cc. flask, 5 cc. of methyl alcohol is added, and a mixture 

 of tenth-normal hydrochloric acid with a little methyl alcohol is allowed to 

 flow in. while a current of air is drawn through the liquid. After 20 cc. of 

 acid have been run in, the stream of air is continued for five minutes, and 

 the solution is then titrated with sodium hydroxid solution, free from carbo- 

 nate and phenolphthalein. The reaction is: NaN03+HCl+CH3.0H=NaCl+ 

 CH3.O.NO + H2O. 



" In the separation of nitric and nitrous acids, a mixture of sulphuric acid 

 and methyl alcohol is placed in the flask, and the solution to be tested, mixed 

 with methyl alcohol, is added drop by drop, air being passed through. The 

 contents of the flask are then washed into a Jena flask, 2.5 to 3 gni. of 

 Devarda's alloy ai'e added, together with 20 gm. of potassium hydroxid, and 

 the ammonia formed is distilled into fourth-normal hydrochloi'ic acid and 

 titrated." 



Controls for the Folin method of estimating creatinin, W. H. Thompson 

 (Jour. Physiol, 46 (1913), No. 2, pp. I, II). — The control against which the 

 Folin standard solution, i. e., seminormal potassium bichromate solution, is 

 usually tested is a solution of creatinin prepared from creatin by boiling with 

 normal hydrochloric acid for 3 to 4 hours, it being assumed that the trans- 

 formation is quantitative and completed in this time. The present investiga- 

 tion tends to disprove that this is the case, as the transformation was found 

 to be variable. 



In seeking other methods for preparing creatinin from creatin, the Folin 

 autoclave method was tried, but without satisfactory results. A picrate of 

 creatinin was then prepared by the autoclave method and of this substance 

 0.0757 gm., which corresponded to 0.025 gm. of creatinin, was dissolved in 

 water and made up to 50 cc. Ten cc. portions were then taken and each 

 of them treated with 14 cc. of a 1.2 per cent picric acid solution and 5 cc. 

 of a 10 per cent sodium hydroxid solution, and after standing for 7 minutes 

 the contents of each tube was diluted with water to 250 cc. Readings were 

 then made against an 8 mm. column of a seminormal solution of potassium 

 bichromate. The readings, which were in the neighborhood of eight, were 

 very satisfactory and corresponded to the Folin value. 



