ABSOUPTIVE POWKU OF THE SOIL. 345 



replaces those ranged to its left in the above series, but 

 none of tliose on its right. Way remarks, that " of course 

 the reverse of this action cannot occur." Liebig {A)in. der 

 Chem. u. Pharm., xciv, 380) drew attention to the fact 

 that Way himself in the preparation of the potash-alumi- 

 na-silicate, demonstrated that there is no invariable order 

 of decomposition. For, as he asserts, this compound may 

 be obtained by digesting cither the lime-alumina-silicate, or 

 soda-alumina-silicate in nitrate or sulphate of potash, when 

 the soda or lime is dissolved out and replaced by potash. 



Way was doubtless led into the mistake of assuming a 

 fixed order of replacements by considering the?;e exchanges 

 of bases as regulated after the ordinary manifestations of 

 chemical affinity. His own experiments show that among 

 these silicates there is not only no inflexible order of de- 

 composition, but also no complete replacements. 



The researclics of Eichhorn, " Ueber die Einwirkung ver- 

 dtinnter Salzlusungen auf Ackererde," {Landwirthschaft- 

 liches Gentralblatt, 1858, ii, 169, and Potyg. Ann., No. 9, 

 1858), served to clear up the discrepancies of Way's in- 

 vestigation, and to conflrm and explain his facts. 



As Way's artificial silicates contanicd about 12 per cent 

 of water, the happy thought occurred to Eichhorn to test 

 the action of saline solutions on the hydrous silicates 

 (zeolites) whii-h occur in nature. He accordingly insti- 

 tuted some trials on chabazite, an abstract of which is 

 here given. 



On digesting finely pulverized chabazite (hydrous sili- 

 cate of alumina and lime) with dilute solutions of chlo- 

 rides of potassium, sodium, ammonium, lithium, barium, 

 strontium, calcium, magnesium, and zinc, sulphate of 

 magnesia, carbonates of soda and ammonia, and nitrate 

 of cadmium, he found in every case that the basic ele- 

 ment of these salts became a part of the silicate, while 

 lime passed into the solution. The rapidity of the re- 

 placement varied exceedingly. The alkali-chlorides re* 

 15* 



