148 



Liquid Manure. 



(Mr. Bennett turns it over three or four times in this period), is 

 fully equal, if not superior, to any thus recommended, most of 

 which I have tried. When mixed with water and spread over 

 land intended for wheat, at the rate of from 2o to 3.5 bushels of the 

 salt and lime to 10 or 15 tons of water per acre (and it answers 

 very nearly as well when carried on the land dry), excellent results 

 are produced. The wheat which I have thus grown on olover- 

 leys has been superior, in height and strength of straw, to any I 

 have seen produced under different modes of treatment, and the 

 seed very bright and heavy. 



All substances, whether organic, earthy, or saline, which are 

 employed to fertilize the soil, or become the food of plants, can 

 only be rendered thus serviceable to vegetation when they are 

 presented to the roots of plants in solution, or in a fluid state ; and 

 although this may appear at first rather a sweeping position, yet 

 such is the real fact, the compost of the farm-yard, the crushed 

 bones of the turnip cultivator, the oil and bones of fish, the gyp- 

 sum of the grazier, the earths, lime, magnesia, and even silica^ 

 and all the saline manures, are dissolved by some process or other 

 before they can be absorbed by vegetables. Every attempt which 

 has been hitherto made to make plants imbibe the most minutely 

 divided powders which chemistry can produce, has been entirely 

 fruitless. Davy ineffectually tried the finest impalpable powder 

 of charcoal, and with much perseverance I have fruitlessly em- 

 ployed the earths, saline substances, and organic matters^ for the 

 same purpose. 



This absolute necessity for every substance which is the food 

 of plants being of a soluble nature did not escape the sagacity of 

 the early Greek and Egyptian philosophers ; it is true they car- 

 ried their conclusions with regard to subjects of natural philosophy 

 too far, as in this instance, when they asserted that water is the 

 only food of plants ; yet they must have patiently noticed many 

 facts in vegetable economy, unaided as they were b}^ the light of 

 modern vegetable chemistry, before they could have arrived at a 

 conclusion so nearly approaching the truth. The idea was pro- 

 bably of Egyptian origin, for the cultivators of that country could 

 not fail to notice the magic fertilizing powers of the waters of the 

 Nile, whose annual overflow is perhaps the most extensive natural 

 irrigation taken advantage of by the cultivators of the earth. 



The same wild dream of water being the sole food of vege- 

 tables was again revived, so lately as 1610, by M. Van Helmont, 

 a celebrated Dutch chemist, who made some very plausible, de- 

 ceptive experiments on a willow-tree, which he watered only with 

 rain w ater ; researches, how ever, whose inaccuracy (owing princi- 

 pally to rain-water, as usually collected, not being quite pure) was 

 shown in 1691, by Mr. Woodward. Although, therefore, it is 



