IO 



Kostitcheff l working with pure compounds, obtained a de- 

 composition of calcium carbonate in the presence of water and 

 phosphates of iron and aluminum. Carbon dioxide was evolved 

 and calcium phosphate was formed. The change took place even 

 when there was present a large excess of iron with respect to the 

 phosphoric acid. 



Tuxen 2 investigated two soils a sand and a clay in order 

 to ascertain the effect of chlorides of sodium and potassium, and 

 sodium nitrate on the absorption of plant food. Phosphoric acid 

 was readily taken up in the presence of the alkalies. Potassium 

 chloride was the most effective, causing an increase in absorption 

 of from 25 per cent to 40 per cent. Solutions of these salts were 

 found to have little effect on the solubility of soil phosphoric acid. 



Krocker and Grahl 3 carried on manuring experiments with 

 phosphates of various kinds. Oats and beets seemed to be little 

 benefited by the soluble phosphates when used alone. When used 

 in conjunction with ammonium sulphate there was decided in- 

 crease in the crop, the greatest yield being obtained by the use of 

 bone meal. 



Similar experiments were made by Hoffmeister 4 . The vari- 

 ous phosphates were applied as a top dressing. The results are 

 interesting. In a sandy soil poor in lime the soluble phosphoric 

 acid did not descend more than ten inches. Di-calcium phos- 

 phate remained unaltered during the experiment, and the mono- 

 calcium phosphate was not converted into the tri-basic form. 



Fleischer and Kissling 5 studied the influence exerted by cer- 

 tain salts on the solubility of the phosphates present in peaty 

 soils. Among the salts used were the sulphate, chloride, and 

 carbonate of potassium,, the sulphate and chloride of calcium, 

 sodium nitrate, ammonium sulphate, and kainite. Potassium 

 Sulphate was very effective, while sodium nitrate and kainite 

 were far less so. 



Gladding 6 claims to have been the first to prove by direct 



1 Bull. Soc. Chim., (2) 1880, 34, 341. 



2 I,andw. Versuchs -Stat., 27, 107. 



3 Bied. Centr., 1882, 1154. 



4 Ibid., 1881, 813. 



5 Ibid., 1883, 153. 



6 Chetn. News, 50, 16, 27. 



