FRENCH AGRICULTURAL METHOD 393 



Another and more rapid method for dissolving the nitrate may 

 also be practiced. In a flask holding about one liter, place 220 

 grams of the soil and 660 cubic centimeters of distilled water and 

 shake vigorously, or enough water to make 660 cubic centimeters 

 together with the moisture remaining in the air-dried sample 

 taken. All the nitrates pass into solution. Throw the contents of 

 the flask into a filter and use 600 cubic centimeters of the filtrate, 

 which will contain all the nitrates in 200 grams of the sample 

 taken. This filtrate is evaporated as described above. 



In the flat dish containing the dried nitrates pour three or four 

 cubic centimeters of ferrous chlorid solution and stir with a small 

 glass rod until complete solution of the nitrates takes place. By 

 means of a small funnel the solution is poured into C, and the 

 capsule and funnel are well rinsed with two cubic centimeters of 

 hydrochloric acid. The washing is repeated three times, as above 

 described, and once with one cubic centimeter of water, which is 

 added cautiously so as to form a layer over the surface of the 

 heavier liquid. The tubulated flask is then connected with the 

 carbon dioxid apparatus, previously freed from air, and the gas 

 allowed to flow evenly until the whole of the interior of the ap- 

 paratus is completely air-free. The other details of the method 

 are essentially the same as those adopted by the Commission of 

 French Agricultural Chemists, which will be given below. 



347. The French Agricultural Method. The Schloesing method, 

 as practiced by the French agricultural chemists, is very 

 slightly different from the procedure just described. 40 The pro- 

 cess with soils and fertilizers poor in nitrogen is carried on as 

 follows : 



Five hundred grams of the sample are introduced into a flask of 

 about two liters capacity and shaken thoroughly with a liter of 

 distilled water. The whole of the nitrates of the soil is thus 

 brought into solution. The solution is filtered ana 400 cubic cen- 

 timeters of the filtrate are used, which correspond to 200 grams 

 of the soil. This liquid is evaporated in a flask, adding a frag- 

 ment of paraffin to prevent foaming, until its volume is reduced 

 to 15 or 20 cubic centimeters. It is afterwards transferred through 

 40 Annales de la Science agronomique, 1891, 1 : 263. 



