350 



were prepared by the use of caustic lime, and just so far as it 

 was so prepared, for reasons which I have given above, no 

 marked effect was to be expected. Lime in a caustic state ap- 

 phed to the soil, may operate to supply, where there is any de- 

 ficiency, the very small amount of calcareous matter which 

 some plants require ,• or to correct any hurtful acids in the soil ; 

 or to operate as a mechanical divider of the soil, rendering it 

 more pervious to light and warmth and rain and air ; or to des- 

 troy insects and grubs. Beyond these effects, I want more ev- 

 idence than I yet have, to satisfy me that it has any valuable 

 use separate from what the mixing of any other ingredient not 

 found in the soil would have. In its application in a caustic 

 state to all animal manures, I believe its effects to be always 

 pernicious and destructive. Lime in the form of a carbonate, 

 unless where reduced by trituration to a very fine powder, has 

 very little effect other than as a mechanical ingredient in the 

 soil, it being almost as insoluble as granite, and requiring not 

 less than 900 parts of water for the solution of 1 of lime. 



The philosophy of manures is yet very imperfectly under- 

 stood. Every intelligent experiment with manures is valuable ; 

 but so many circumstances must go in every case to affect 

 the result — such as the kind of manure, its condition, its 

 quantity, the mode of its application, the time of its applica- 

 tion, the plant to which applied, the nature of the soil, the 

 condition of the soil, and many nameless contingencies — that 

 an experiment, to be the ground of certain and positive con- 

 clusions, must be conducted and detailed with the greatest ex- 

 actness, and be many times carefully repeated. Much advan- 

 tage may be expected, as has often been suggested, from the 

 chemical analysis of soils ; but we must not be too sanguine in 

 our expectations, even from this source. If the process of veg- 

 etation were as simple as some men would have us believe, we 

 might then hope much more from chemical analysis than we 

 can now expect. I do not doubt that every process in nature, 

 however mysterious in its appearance to us is, properly speak- 

 ing, simple, that is depending on certain elements and laws 



