ABSORPTIVE POWER OF THE SOIL. 847 
monia, in order fo ascertain whether the formation of a 
soluble salt of the displaced base limited the reaction ; 
but the results were substantially the same as before, as 
shown by analyzing the residue after removing carbonate 
of lime by digestion in dilute acetic acid. 
Eichhorn found that the artificial soda-chabazite re-ex- 
changed soda for lime when digested in a solution of 
chloride of calcium; in solution of chloride of potassium, 
both soda and lime were separated from it and replaced 
by potash. So, the ammonia-chabazite in solution of chlo- - 
ride of calcium, exchanged ammonia for lime, and in so- 
lutions of chlorides of potassium and sodium, both am- 
monia and lime passed into the liquid. The ammonia- 
chabazite in solution of sulphate of magnesia, lost ammo- 
nia but not lime, though doubtless the latter base would 
have been found in the liquid had the digestion been con- 
tinued longer. 
It thus appears that in the case of chabazite all the 
protoxide bases may mutually replace each other, time 
being the only element of difference in the reactions. 
Similar observations were made with natrolite (hydrous 
silicate of alumina and soda,) as well as with chlorite and 
labradorite, although in case of the latter difficultly de- 
composable silicates, the action of saline solutions was 
very slow and incomplete. 
Mulder has obtained similar displacements with the 
zeolitic minerals stilbite, thomsonite, and prehnite. (Che- 
mie der Ackerkrume, I, 396). He has also artificially 
prepared hydrous silicates, having properties like those 
of Way, and has noticed that sesguioxide of iron readily 
participates in the displacements. Mulder also found that 
the gelatinous zeolitic precipitate obtained by dissolving 
hydraulic cement in hydrochloric acid, precipitating by 
ammonia and long washing with water, underwent the 
game substitutions when acted upon by saline solutions, 
