METHOD OF SCHLOESING-WAGNER 397 



The solutions of the pure salts and of the sample to be analyzed 

 are made of such a strength as to contain 66 grams of sodium 

 nitrate, or 80 grams of potassium nitrate, in a liter. Five cubic 

 centimeters of such a solution will yield a little less than 100 

 cubic centimeters of nitric oxid under usual conditions. Let 

 the volume of gas obtained with the pure salt be v, and that 

 with the sample be v' . The calculation is then made from the 



' x 



equation : = . 



v 100 



Example. Let 95 cubic centimeters be the volume of gas from 

 five cubic centimeters of the pure salt (sodium nitrate), and 91.5 

 cubic centimeters be the volume of gas from five cubic centi- 

 meters of the sample; then = - , whence x = 96. *i. 



95 ioo 



Hence the sample analyzed contains 96.31 per cent, of sodium 

 nitrate. Since the pure sodium nitrate contains 16.47 P er cent, of 



nitrogen, the sample under examination would contain 



15.86 per cent. 



It is evident that this comparative method is quite easy of ap- 

 plication when the sample under examination has no other nitrate 

 in it except that combined with the one base. 



349. Method of Schloesing-Wagner. The schloesing-wagner 

 method for estimating nitrogen in the nitrates of fertilizers is 

 carried out at the Halle experiment station as follows :" 



A flask, Fig. 21, of about 250 cubic centimeters capacity, is 

 provided with a rubber stopper with two holes. Through one 

 of them is passed the stem of a funnel carrying a glass stop-cock. 

 The other carries a delivery tube leading to the receiving vessel. 

 The end of the delivery tube is bent so as to pass easily under 

 the mouth of the measuring burette and is covered with a piece 

 of rubber tubing. 



Fifty cubic centimeters of saturated ferrous chlorid solution 

 and the same quantity of 10 per cent, hydrochloric acid are 

 placed in the flask. The ferrous chlorid solution is obtained 



41 Bielerand Schneidewind, Die agricultur-chemische Versuchsstation, 

 Halle a S, 1892 : 51. 



