206 Outlines of Hortmdtural Chemistry, 



.vicinity of their roots, without the latter source being dimi- 

 nished; and that plants are benefited by such additional 

 application to their radiculae, has been proved by the experi- 

 ments of Mr. Hill, quoted in a previous part of these outlines. 

 The question may also be asked, whether the roots have the 

 power to extract the oxygen from its combination. That they 

 have admits of little doubt, since Saussure found that they 

 were able to extract various saline bodies from their combin- 

 ations ; not only extracting, but selecting in those cases where 

 several salts were in the same solution. Carbonic acid is also 

 of benefit to plants, when applied to their roots in an advanced 

 stage of their growth. Animal and vegetable matters evolve 

 this gas whilst putrefying, but I am not aware of any manure 

 that absorbs it from the atmosphere, so as to .be for that reason 

 beneficial to vegetation. Lime attracts it rapidly, but com- 

 bines with it so strongly, that it is useless to the plant, until 

 the carbonate of lime so formed is imbibed and elaborated. 



Manures assist plants, by destroying predatory vermin and 

 weeds. This is not a property of animal and vegetable ma- 

 nures : they foster both those enemies of our crops. Salt and 

 lime are very efficient destroyers of slugs, snails, grubs, &c. 

 It is astonishing how ignorantly neglectful are the cultivators 

 •of the soil, when their crops are devastated by the slug, 

 not to dress them so as to render the surface of the soil quite 

 white, during a promise of a few days' dry weather, widi 

 caustic lime. It is instant destruction to every slug it falls 

 upon, and those whom it misses, are destroyed by their 

 coming in contact with it when moving in search of food. It 

 is a common practice to burn couch-grass, docks, gorse, and 

 other vegetables which are very retentive of life, or slow in 

 decay : a more uneconomical, unscientific method of reducing 

 them to a state beneficial to the land of which they were the 

 refuse, cannot be devised. In breaking up heaths, such 

 exuviae are very abundant; but, in all cases, if the weeds, 

 leaves, &c., were conveyed to a hole or pit, and, with 

 eveiy single horse-load, and with barrow-loads in propor- 

 tion, a bushel of salt and half a bushel of lime were incorpo- 

 rated, it would, in a few months, form a mass of decayed 

 compost of the most fertilising quality; the lime retaining 

 many of the gases evolved during the putrefaction of the 

 vegetable matter, and the salt and it combining to destroy 

 noxious animals which might form a nidus in the mass. By 

 this plan, nearly all the carbonaceous matters of the refuse 

 vegetables are retained ; by burning, nearly all of them are 

 dissipated. The forming of a compost such as that recom- 

 mended, is justified and approved by the experience of many. 



