METHOD OF SCHLOESING 391 



perchlorate. One equivalent of silver nitrate corresponds to one 

 equivalent of potassium perchlorate. 



343. Method of Blattner-Brasseur/- 7 In this method five grams 

 of saltpeter, which has been freed from moisture by heat- 

 ing to 150, are treated with from seven to eight grams of 

 pure chlorin-free calcium hydrate in a porcelain or platinum 

 crucible of about 25 to 30 cubic centimeters capacity and the 

 covered crucible heated for 15 minutes over a bunsen. The ig- 

 nited mass is dissolved and neutralized with nitric acid and the 

 chlorin titrated with nitrate of silver or estimated by the gravi- 

 metric method as above described. 



THE NITRIC ACID PROCESS 



344. Occurrence of Highly Oxidized Nitrogen. The nitrogen 

 of fertilizers, soil waters, etc., often exists in a highly oxidized 

 state as nitrous or nitric acid or compounds thereof. The fol- 

 lowing paragraphs are devoted to the description of methods 

 employed for estimating nitrogen in these states of combination 

 and the principles on which they are based. The processes for 

 estimating nitrogen by combustion with copper oxid and by 

 moist combustion with sulfuric acid have both been used for the 

 determination of the quantity of nitrogen existing in a highly 

 oxidized state. These processes have been fully discussed under 

 their proper heads. In the case of soil extracts, drainage waters, 

 etc., it will be sufficient to discuss, for the present, only those pro- 

 cesses adapted especially to a quick and accurate estimation of 

 oxidized nitrogen when occurring in relatively small quantities. 



345. Method of Schloesing. The principle of the method of 

 Schloesing depends on the decomposition of nitrates in the pres- 

 ence of a ferrous salt and a strong mineral acid. 38 The nitrogen 

 in the process appears as nitric oxid, the volume of which may 

 be directly measured, or it may be converted into nitric acid and 

 titrated by an alkali. 



87 Chemiker-Zeitung, 1900, 24 : 767. 



38 Annales de Chimie et de Physique, 1854, [3], 40 : 479- 



Zeitschrift fur analytische C'hemie, 1870, 9 : 24. 



Die landwirtscbaftlichen Versuchs-Stationen, 1869, 12 : 164. 



Journal of the Chemical Society, 1880, 37 1468; 1882, 41 : 345; 1889, 

 55 : 537- 



