KESULTS OF EXPERIMENTS WITH THEM. 167 



8. Results of experiments made with the silicates of potash 

 and soda. 



Lampadius first observed that silicate of potash produced 

 remarkable effects on Indian corn and on rye. It has since 

 been supposed by many that, as our grasses and the straw of 

 our grain plants contain so much silica, the artificial application 

 of soluble silicates to such crops would be attended with much 

 benefit. Especially by those who held that the function of silica 

 in the straw was to give it strength, it was recommended to 

 apply these silicates when the straw of wheat or of oats was apt 

 to be laid. Mr Lawes, however, states, as the result of repeated 

 experiments, that these silicates do no good to grain plants.* 



Some years ago I showed,f first, that all our cultivated soils 

 contain a sensible proportion of silica in a soluble state ; second, 

 that all our springs and streams of water contain an appreciable 

 quantity of silica dissolved in them ; and third, that the roots 

 of plants had the power of taking up silica from the soil even 

 when it contained nothing which strong acids could extract from 

 it, and of conveying this silica into their sap. I hence inferred 

 that, as a general rule, the artificial addition of soluble silicates 

 to the soil was not necessary, though it might be useful, and was 

 therefore deserving of trial by experiment. 



Few accurate experiments, however, with these silicates, 

 applied alone, have as yet been made and published. The 

 following are all I have hitherto met with : 



1. To oats grown upon moss land Mr Fleming of Barochan, 

 in Kenfrewshire, applied silicate of soda on the 29th of May 

 1845, with the following results per imperial acre : 



Grain. Straw. Weight per bushel. 



No application gave . 47 bushels 30^ cwt. 38 Ib. 

 Silicate of soda (2 cwt.) gave 49 ... 37^ ... 39 ... 



The growth of straw was here promoted, but the quantity 

 of grain was not materially increased. He considered the 

 straw to be stronger in this case, as well as in several other 



* Jownal of the Royal Agricultural Society, viii. p. 259. 

 t Contributions to Scientific Agriculture, pp. 50-56. 



