Ii6 ARTIFICIAL NITROGENOUS MANURES 



phosphide, which produce noxious gases on moistening with water. 

 For this latter reason it should be incorporated with the soil 

 a week or so before any seed is sown. 



08. Qualitative Examination. 



{a) Some nitrolim is moistened with water in an 

 open dish. The smell of acetylene generally produced 

 may be noted, and the gases formed should be tested 

 for free ammonia by means of litmus and turmeric 

 paper. During the moistening process the manur^ 

 will be found to heat up, owing to the slaking of the 

 free lime. 



{U) A small portion of the manure is fused with 

 three times its bulk of common salt. The mass is 

 extracted with water and filtered. The presence of 

 cyanide in the solution may be readily shown by adding 

 a few drops each of ferrous sulphate and ferric chloride. 

 On acidification with KCl a precipitate of prussian 

 blue is formed. 



09. Analysis of Nitrolim. 



{a) Nitrogen. — The nitrogen is best estimated by 

 digestion with strong sulphuric acid by the ordinary 

 Kjeldahl process. 



{b) Carbon and Insoluble Matter. — About 2 grams 

 of the manure are warmed with 50 to 100 c.c. of water, 

 and the mixture filtered on a tared filter paper while 

 still hot. The undissolved material is washed back 

 into the beaker and boiled with dilute hydrochloric 

 acid for a few minutes, and the residue again transferred 

 to the filter paper, where it is washed with dilute acid 

 until the filtrate no longer contains calcium salts in 

 solution. The residue is then washed well with water, 

 dried in the steam oven, and weighed. This gives the 

 carbon and insoluble matter together. Filter paper 



