344 HOW CROPS FEED. _ 
This compound is analogous in constitution to the 
zeolites, in so far as it is a highly basic silicate containing 
water, and is easy of decomposition. It is, in fact, de- 
composed by water alone, which removes from it silicate 
of soda, leaving insoluble silicate of alumina. 
On digesting this soda-silicate of alumina with a solu- 
tion of any salt of lime, Way found that it was decom- 
posed, its soda was eliminated, and a Jime-silicate of 
alumina was produced. In several instances he succeeded 
in replacing nearly all the soda by lime. Potash-silicate 
of alumina was procured by acting on either the soda or 
lime silicate with solution of a potash-salt ; and, in a simi- 
lar manner, ammonia and magnesia-silicates were gener- 
ated. In case of the ammonia-compound, however, Way 
succeeded in replacing only about one-third of soda or 
other base by ammonia. All of these compounds, when 
acted upon by pure water, yielded small proportions of 
alkali to the latter, viz. : 
The soda- silicate gave 3.36 parts of soda to 10,000 of water. 
The potash- 7 ce Oz) ce see potash “ ‘“ eed 
The ammonia- ‘* “1.06. “ —“ sxumogia Seep 
Way found furthermore that exposure to a strong heat 
destroyed the capacity of these substances to undergo the 
displacements we have mentioned. 
From these facts Way, concluded that there exist in all 
cultivable soils, compounds similar to those he thus pro- 
cured artificially, and that it is their presence which oc- 
casions the absorptions and displacements that have been 
noticed. 
Way gives as characteristic of this class of double sili- 
cates, that there is a regular order in which the common 
bases replace each other. He arranges them in the fol- 
lowing series: 
Soda—Potash—Lime—Magnesia—Ammonia;: 
and according to him, potash can replace soda but not the 
other bases ; while ammonia replaces them all ; or each base 
‘ 
. . . a 
-_ 
Be — _ 5 = wv 
a ee eae ee 
