108 PRINCIPLES OF GARDENING. [CH. II. 



plied to their roots in an advanced stage of their 

 crro\vth. Animal and vefretable matters evolve this 

 gas whilst putrefying ; and 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 combines with it so strongly. 

 that it is useless to the plant, imtil the carbonate of 

 lime so formed is imbibed and elaborated. 



Manures assist plants, by destropng predatory 

 vermin and weeds. This is not a property of animal 

 and vegetable manures — they foster both those ene- 

 mies of oui' crops. Salt and lime are veiy efficient 

 destroyers of slugs, snails, grubs, &c. It is astonish- 

 ing how ignorantly neglectful are the cultivatoi*s of 

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

 not to dress them Avith caustic lime, so as to render 

 the surface of the soil quite white, duiiiig the pro- 

 mise of a few days' diy weather : it is instant destruc- 

 tion to eveiy slug it falls upon ; and those that it 

 misses, are destroyed by their coming in contact A\-ith 

 it when moving in search of food. 



It is a common practice to bum couch-grass, docks, 

 gorse, and other vegetables, which are veiy retentive 

 of life, or slow in decay : a more uneconomical, un- 

 scientific method of reducing them to a state bene- 

 ficial to the land of which they were the refuse, can- 

 not be devised. In breaking up heaths, such exuviae 

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



