ULSCH METHOD 445 



to the analysis of nitrates contained in drinking and drainage 

 waters, and it is regarded by him as one of the best methods to 

 be employed in such investigations. 67 



The method of Ulsch has given entirely satisfactory results, and 

 is generally used in preference to other methods in cases where 

 a considerable quantity of nitrates is present. It is based on the 

 following reactions: 



2KNO,+H 2 SO 4 =K 2 SO 4 +2HNO, 



2HNO 3 +8H,=2NH 3 4-6H 2 O 



2NH.+H a s6 4 =(NHJ 1 Sb 4 . 



384. Ulsch Method Applicable to Mixed Fertilizers. The 

 method of Ulsch, which is found to give good results with pure 

 nitrates or with nitrates in the absence of other forms of nitrogen, 

 may also be adapted to mixed fertilizers containing nitrogen in 

 more than one form. Street has developed such a method and 

 shown, by analytical data, that it is applicable in a great num- 

 ber of cases. 08 The variation is based on the substitution of mag- 

 nesia for soda in the distillation and is carried on as follows : 



Place one gram of the sample in a half-liter flat-bottomed flask. 

 Add about 30 cubic centimeters of water, one gram of reduced 

 iron, and 10 cubic centimeters of sulfuric acid diluted with an 

 equal volume of water, shake well, and allow to stand for a 

 short time. This will remove the danger of an explosion caused 

 by the otherwise violent action which takes place. Close the 

 neck of the flask with a rubber stopper through which passes a 

 glass dropping-bulb filled with water. The flask having been 

 stoppered, place it on a slab to which a moderate heat is applied. 

 Allow the solution to come slowly to a boil and then boil for 

 five minutes and cool. Add about 100 cubic centimeters of water, 

 a little paraffin, and about five grams of magnesium oxid. Boil 

 for 40 minutes, after which time all the ammonia will be dis- 

 tilled, and collect the ammonia in set acid. 



The magnesia causes a slight frothing, which can easily be 

 controlled by adding a little paraffin and by bringing to a boil 

 very gradually. Fully 40 minutes are necessary to distil all the 



87 Zeitschrift fiir angewandte Chemie, 1891, 4 : 241. 

 68 Division of Chemistry, Bulletin 35, 1892 : 88. 



