loo A TREATISE ON THE CONNECTION OK 



of the plants. This explication of the beneficial effects 

 arising to vegetation by stagnated air, will also account 

 for the benefit which plants of a certain construction of 

 stemand leaf* and which very much overshadow and co- 

 -1?er the ground, ultimately receive, by preventing a free 

 circulation of air. The application of long or short dung to 

 ground, must appear too material to the practical farmer 

 to be overlooked. The preference, in most cases, is un- 

 doubtedly to be given to such dung as has most com- 

 pletely undergone the putrefactive process. Under this 

 head it is necessary to notice, that dung and urine newly 

 voided (unless when animals are diseased) are not in a 

 putrescent state, The time of retention in the body 

 of animals is of too short a continuance to allow that 

 effect to take place. Such excrements are in a state 

 advancing towards putridity, or in a small degree 

 only putrid ; a process which, to a certain extent, is ne- 

 cessary to stimulate the intestines to discharge the fxces. 



The further putrescency of excrements is promoted 

 by a clue degree of heat and moisture, particularly when 

 aided by certain saline matters. The most efficacious 

 are neutral salts, containing the vitriolic acid ; such as 



vitrio- 



