38 PRACTICAL FARM CHEMISTRY. 



food to plants. It removes the sourness of sour 

 soils, yielding carbonic acid, and promotes the slow 

 growth or formation, from nitrogen compounds, of 

 nitric acid, with which it combines, forming nitrate 

 of lime, a compound having about the same value 

 as plant food and the quick effect of nitrate of soda. 

 On heavy clay soils it also exerts a beneficial me- 

 chanical action, rendering them more open and 

 porous, helping to admit air, and to liberate locked- 

 up plant foods. 



It will be seen from all this that the application 

 of lime, in one form or another, is decidedly bene- 

 ficial to a certain extent, and especially so far as 

 immediate results are concerned. When overdone 

 or long continued, however, lime applications with- 

 out other fertilizer tend to ultimate soil exhaustion 

 by hastening the removal of the scarcer and more 

 valuable plant foods (potash, phosphoric acid and 

 nitrogen), either when consumed by and taken off 

 with the crops, or when allowed to escape into the 

 drains, as all nitrates are inclined to do, unless 

 caught and held by growing plants. It is good logic 

 what our forefathers expressed in the rhyme : 



Lime without manure 



Makes the father rich and the children poor. 



The refuse lime of the gas works is frequently 

 spoken of both as a fertilizer or rather stimulant, 

 and as a repeller or destroyer of injurious insects. 

 Prof. Caldwell, of Cornell University, gave me his 

 opinion of its value as follows: 



''Gas lime is composed chiefly of carbonate of 



lime and varying quantities of sulphate of lime (or 



ordinary land plaster), sulphite of lime, 



sulphide of lime, and more or less 



unchanged lime. The sulphite and sulphide are 



