804 EXPERIMENT STATION EECOKD. 



phate is the only substance with which this enzym can be salted out (potassium 

 chloi'id, potassium sulphate, sodium chlorid, sodium sulphate, sodium phos- 

 phate, potassium phosphate, ammonium nitrate, magnesium chlorid, mag- 

 nesium' sulphate, calcium nitrate, and zinc sulphate could not be used) ; (3) 

 the nitrogen content of the various precipitates is no criterion in regard to the 

 activity; (4) no diastatic enzym could be separated by dialyzing through parch- 

 ment paper; (5) small additions of sugar to enzym solutions have no effect 

 upon the hydrolytic process, but a large amount of maltose (saccharification 

 products), on the other hand, inhibits the process; (C) the optimum and lethal 

 temperatures of diastase of different origins are different; (7) the diastatic 

 capacity of diastase which has been weakened by heat can be increased by 

 certain additions, such as sodium chlorid and egg white, peptone, or asparagin ; 

 and (8) the Hamburg and Frankel chemical-biological method for the precipi- 

 tation of diastases is not efBcient. 



Modification of the diphenylamin test for nitrous and nitric acids, W. A. 

 Withers and B. J. Ray (North CaroUna Sta. Rpt. 1910, pp. 56-58).— Combining 

 some of the features of the different methods the authors have prepared a 

 reagent which in their hands has proved to be very delicate. It is made as 

 follows : 



" Seven hundred mg. of diphenylamin are dissolved in a mixture of 60 cc. of 

 concentrated sulphuric acid and 28.8 cc. of distilled water. The resulting 

 mixture is thoroughly cooled and 11.3 cc. of concentrated hydrochloric acid 

 (specific gravity 1.19) are added slowly — making the hydrochloric acid content 

 5 per cent. After standing over night some of the base separates showing that 

 the reagent is saturated. The test with the diphenylamin reagent as prepared 

 by [the authors] is conducted as follows : Place 1 cc, of the liquid to be tested in 

 a clean test tube ; add 1 drop of the diphenylamin reagent and mix thoroughly 

 by shaking. From a pipette is added 2 cc. of concentrated sulphuric acid, 

 while the tube is held at an angle so as to form 2 layers of the liquids. The 

 tube is gently agitated so as to cause a slight mixing of the liquids at the plane 

 of contact, and it is then placed in a bath at the temperature of 40° and left 

 for 15 or 20 minutes. This method will reveal the presence of 1 part of nitrite 

 nitrogen in 25.000,000 or 1 part of nitrate nitrogen in 35,000,000. By heating 

 for 1 hour instead of 15 or 20 minutes the test will show 1 part of nitrite 

 nitrogen in 32,000,000 or 1 part of nitrate nitrogen in 44,000,000." 



Test for nitric acid, F. Klein {Jour. Indus, and Engin. Chem., 2 (1910), No. 

 9, p. 389; al)s. in Jour. Soc. Chem. Indus., 29 (1910), No. 20, p. 1200).— The 

 reagent used in this test is made by adding a little powdered tellurium to from 

 2 to 3 cc. of fuming sulphuric acid, and then from 1 to 2 cc. of 95 per cent 

 sulphuric acid. 



When a little of a nitrate or strong nitric acid is added to the reagent and 

 heated, the eosin-red color which the reagent possesses is discharged. When 

 dilute nitric acid (less than 40 per cent) is present, it is neutralized and the 

 solution is evaporated to dryness before the test is complete. It was found 

 that a solution consisting of 0.1 gm. of tellurium in 10 cc. of fuming sulphuric 

 acid and 10 cc. of 95 per cent sulphuric acid is decolorized by 0.G6 gm. of GG 

 per cent nitric acid. 



The use of the above principle as a basis for quantitative colorimetric tests 

 is pointed out. 



New method for the rapid determination of nitrate nitrogen, A. Quartaroli 

 (Staz. Sper. Agr. Itah, .',// (1911), No. 2, pp. 157-lG.'f; ads. in Chem. Zentbl, 

 1911, II, No. 1, pp. .'{9, 50; Jour. Soc. Chem. Indus., 30 (1911), No. U, p. 926).— 



