107 



Since Peter's solution and the alkaline ammoninm oxalate contain a salt of 

 ammonia, it was thought that the phenomena of soil absorption might come into 

 play. To test this, a solution of the same alkalinity, but containing the sam^ 

 amount of ammonia as chloride as was contained in the other solutions in the 

 form of oxalate, was used. To test the question of soil absorption pure and 

 simple, a neutral solution of ammonium chlorid, 17.2 grams to the liter, the same 

 amount of ammonium chlorid as in the previous solution was used. 



The soils were also digested with ammonium hydrate, sp. gr. 0.96, containing 

 17.2 grams ammonium chlorid per liter, and with ammonium hydrate, sp. gr. 0.96 

 alone. Ammonium hj'drate was tried, because, as I have previously shown^, 

 phosphates of iron and alumina are dissolved by ammonium hydrate. At first 

 we hoped to utilize the ammonia and ammonium chlorid mixture, but in the 

 presence of the ammonium chlorid not a trace of phosphoric acid was dissolved. 



On the Kentucky soils a number of solvents were tried at a higher tempera- 

 ture. This modification seemed no improvement — rather the reverse ; and it was 

 decided to use room temperature. 



Table II contains the results of the work. The total potash in each soil, and 

 the amount of potash and phosphoric acid removed by hydrochloric acid, sp. gr. 

 l.ll"), are also added for the purpose of comparison: 



