416 LIME KILLS INSECTS AND SEEDS. 



tures which bear shells. In highly limed land the former may be seen 

 crowded at the roots of the hedges, from which they make frequent in- 

 cursions upon the young crops, and are, I believe, especially hurtful 

 to the turnips. 



2°. It is found to prevent smut in wheat. For this purpose the 

 seed is steeped in lime, and afterwards dried with slaked lime, or lime 

 water is poured up;^ the heap of corn, which is turned over, and left 

 for 24 hours (Hillyard.) 



3^. It is also said to prevent the rot and foot-rot in sheep fed upon 

 pjistures on which, before hming. the stock was liable to be affected 

 by these diseases (Prideaux.) 



4°. In regard to its action upon living plants, it is certain that it ex- 

 tirpates certain of the coarser grasses from sour pastures and brings up 

 a tenderer herbage ; but practical men appear to differ in regard to its ef- 

 fects upon the roots and seeds of the more troublesome weeds. Accord- 

 ing to some, the addition of lime to a compost, or to the soil, will kill 

 the roots of weeds and render unproductive such noxious seeds as may 

 happen to be present. According to others (p. 405,) this is a mistake. 

 I believe the truth to be, that lime will lead to their destruction and 

 decay, if the circumstances are favorable or if proper pains be taken 

 to effect it. But air and moisture are necessary to insure this, as they 

 are to effect the rapid decay of dead organic matter. If the ingre- 

 dients of the compost be duly proportioned, or if the dose of lime 

 added to the land be sufficiently large, and if in each case the mix- 

 ture be frequently turned, the final destruction of roots and seeds may 

 in general be safely calculated upon. 



§ 34. Use of silicate of lime. 



There is one compound of lime which, though occurring occasionally 

 m all soils, has not hitherto been applied to the improvement of the land 

 even in localities where it most abounds. This compound is the silicate 

 of lime. I have already directed your attention to the presence of this 

 compound in the trap rocks, and to the fertile character which it imparts 

 to the soils which are formed by the natural degradation of these rocks. 



In those districts where the smelting of iron is carried on, the first 

 slag that is obtained consists in great part of silicate of lime. This 

 slag accumulates in large quantities, and is employed in some dis- 

 tricts for mending the roads. It is not unworthy the attention of the 

 practical farmer — as an improver of his fields — especially where caus- 

 tic lime is distant and expensive, or where boggy and peaty soils are 

 met with in which vegetable matter abounds. On such land it may 

 be laid in large quantity. It will decompose slowly, and while it im- 

 parts to the soil solidity and firmness, will supply both lime and silica 

 to the growing crops, for a long period of time. 



I have thuB drawn your affention to the most important topics connected with the use of 

 lime, so efRcacinijs an iiisfrnmenf in the han(isorthe skilful arid impiovinsr farmer forame- 

 lioralin2 the condition and increasing the productiveness of his land. If I have appeared 

 to dwell long upon this subject, it is because of (he value which I know to be attached by 

 pr.ictical men to a correct exposition of the virtu<>s of lime and of tlie theory by which its 

 effects are to be e.^plained. I believe thai in the theoretical part I have been able to point 

 om to you the leading chemical principles upon which its influence depends— if any thing 

 is still dark, it is becnn^e our knowledge is not yet complete. A few years more, and we 

 may hope to have the mists which hanjr over this, as over many other branches of agricul- 

 tural chemistry, in a great measure cleared away. 



