HISTORICAL 



The fact that soils are capable of absorbing certain substances- 

 from solution has been known for nearly a century. There has 

 been much discussion as to whom the credit for this discovery is 

 due. The first authentic record appears to have been made by 

 Gazzeri in 1819. He says : "If extract of dung strongly colored 

 and containing nutritive matter is added to a clayey soil, the liquid 

 is rapidly decolorized. The soil takes hold of the substances in 

 solution, and forms with them compounds which are insoluble,, 

 but which are decomposed by the absorbing action of plants." 



Bronner in his treatise on "Grape Culture in South Ger- 

 many" published in 1836, made similar statements regarding the 

 action of sand and garden soil, and HuxtableMn 1848, apparently 

 ignorant of previous experiments, repeated the work of Gazzeri.. 

 A little later the work of these observers was extended somewhat 

 by Thomson 2 of England. 



In 1850 Way 3 made a systematic investigation of the absorb- 

 ing power of soils. His efforts were directed almost exclusively 

 toward ascertaining the cause and nature of the absorption of 

 bases. He published only one experiment on the absorption of 

 phosphoric acid. When a solution containing calcium acid phos- 

 phate was filtered through a soil, no trace of phosphoric acid was 

 found in the filtrate. 



The next work bearing on the subject was that of Wicke 4 , 

 who found that pure marble kept in contact with a solution of 

 superphosphate evolved carbon dioxide, and the greater part of 

 the phosphoric acid was precipitated. 



Thenard 5 was the first to make any systematic study of the 

 absorption of phosphoric acid by soils. He succeeded in decol- 

 orizing the liquid from barnyard manure by the use of iron and 

 aluminum hydroxides, and calcium carbonate. He concluded 



1 Jour. Roy. Agr. Soc., England. 



2 Ibid., 1850, n,68. 



3 Ibid., 1850, ii, 313. 



4 Ann. Chem. Phar., 1856, 99, 97. 



5 Compt. rend., 44, 819. 



