704 



EXPEKIMENT S'l'ATIoN RKCOKl). 



"Most of these soils liave been under cultivation from 5 to 30 years. 



"The first impression of the results would indicate that the weak point is in the 

 potash content. ... In many of these soils the total iwtash amounts to as much as 

 2.5 per cent, while the amount of potash soluble in acid amounts to only a little over 

 0.20 per cent. There is every indication . . . that much of the potash that is insolu- 

 ble in the acid possesses agricultural value. . . . 



"These analyses, as well as those reported in former jiublications, show that most 

 of the typical soils of the State are well supplied Avith phosphoric acid. . . . 



"There is a good content of lime in most of the typical soils of the State." 



The action of organic and mineral acids upon soils, H. Snyder 

 (Jour. Amer. Chem. Soc, 17 {1895), No. 2, P2). 118-151). — Comparative 

 tests of the solvent action of hydrochloric acid of 1.115 sp. gr. ; 10 per 

 cent solutions of citric, oxalic, and tartaric acids; and a 10 i)er cent 

 mixture of the last three, were made on the same sample of soil. Tlie 

 digestion was carried on for 3G hours in the Snyder soil tlask (see p. 689). 



The results obtained were as follows : 



Solvent action of liijdrochloric and organic acids upon soil. 



Total insoluble matter 



Potash 



Soda 



Lime 



Magnesia 



Irou oxid 



Alumina 



Phosphoric anhyilrid.. 

 Sulphuric anhyilrid . . . 



Hydro- 

 chloric 

 acid 1.115 

 sp. gr. 



Per cent. 

 84.08 

 0.30 

 0.25 

 0.51 

 0.2G 

 2.56 

 4.24 

 0.23 

 0.U8 



Ten per cent solution of- 



Citric 

 acid. 



Per cent. 

 87.90 

 0.12 

 0.17 

 0.50 

 0.27 

 1.59 

 1.45 

 0.26 

 0.10 



Oxalic 

 acid. 



Per cent. 

 85.07 

 0.18 

 0.19 

 0.23 

 0.21 

 1.14 

 3.96 

 0.14 

 0.05 



Tartaric 

 acid 



Per cent. 

 87.67 

 0.06 

 0.05 

 0.41 

 0.32 

 1. 62 

 1.77 

 0.11 

 0.06 



Organic 



acid 

 mixture. 



Per cent. 

 85. 93 

 0.10 

 0.12 

 0.45 

 0.33 

 2.23 

 2.99 

 0.26 

 0.05 



"The oxalic acid possesses the greatest solvent action upon the complex insoluble 

 matter of an alkaline nature. The citric acid possesses the greatest solvent action 

 upon the lime, magnesia, and the sulphuric and phosphoric anhydrids. The amount 

 of lime dissolved b\' the oxalic acid is greater than would at first be expected, but 

 the complex nature of the solution and the presence of the salts of other metals has 

 caused nearly half as much lime to be dissolved by the oxalic acid as by the hydro- 

 chloric acid of 1.115 sp. gr. 



" The 10 per cent mixture of the 3 organic acids has resulted in dissolving as much 

 phosphates and magnesia and nearly as much lime as any one of tlie acids acting 

 alone. The potash does uot appear to be as soluble in the organic acid mixture as 

 the other elements of plant food. 



"The amount of potassium, iron, and aluminum oxids dissolved by these 3 organic 

 acids and their mixtures is somewhat less than that dissolved by the hydrochloric 

 acid. . . . The main ditference between the solvent action of the hydrochloric and 

 the organic acids is in the somewhat smaller amount of potash dissolved by the 

 organic acids. 



" With the exception of the solubility of the potash, as noted, these results bring 

 out in a general manner the value of hydrochloric acid of 1.115 sp, gr. as a solvent 

 over the organic acids of 10 per cent strength, because the hydrochloric acid repre- 

 sents the limit of the solvent action reached by any one of the organic acids acting 

 alone or in a mixture." 



