92 PEINCIPLES OF GARDENING. [CH. II. 



manure is usually employed by gardeners, as being 

 of immediate benefit, admitting of clean liusbandr}', 

 and as economy is not, in private estaldisliments, the 

 generally presiding genius of the gardens. If stable 

 dung or other manure be allowed to putrefy in an 

 uninclosed heap, the loss is immense ; all the gases 

 which pass off during decomposition, all the soluble 

 matters which drain away, are highly nutritious to 

 plants, as has been proved by Davy and othei-s. If 

 the decomposition be thus allowed to proceed until 

 the heap becomes a saponaceous mass, the loss can- 

 not be less than 50 per cent. Notmthstanding all 

 the reasoning of chemists, however, putrefied dung 

 will continue to be used ; it admits of clean workman- 

 ship, \nth less labour, and insures a good immediate 

 crop : to prevent as much loss as possible, therefore, 

 the dmig-heap should be in a brick cistern, and 

 covered over with eaith at 'least nine inches deep, 

 with a well at one comer to retain the drainage, 

 which from time to time, should be returned over 

 the heap. 



The chief component of plants is carbon, and we 

 shall not be far wrong if we estimate it as constituting 

 50 per cent, of eveiy vegetable : it is the decayed! 

 organic remains of the soil which supply a consider- 

 able portion of this to the growing plants. It is a 

 subject of debate amongst chemists, how the carbon of 

 manures is imbibed by plants. Carbon, say they, is 



