C 17] 



from decomposing animal and vegetable substances 

 depend upon the knowledge of these principles, and 

 I shall be able to produce some new and important 

 facts founded upon them, which I trust will remove 

 all doubt from this part of agricultural theory. 



The chemistry of the more simple manures ; the 

 manures which act in very small quantities, such as 

 gypsum, alkalies, and various saline substances, has 

 hitherto been exceedingly obscure. It has been gen- 

 erally supposed that these materials act in the vegetable 

 ceconomy in the same manner as condiments or stimu- 

 lants in the animal ceconomy, and that they render the 

 common food more nutritive.- -It seems, however, a 

 much more probable idea, that they are actually a 

 part of the true food of plants, and that they supply 

 that kind of matter to the vegetable fibre, which is 

 analogous to the bony matter in animal structures. 



The operation of gypsum, it is well known, is 

 extremely capricious in this country, and no certain 

 data have hitherto been offered for its application. 



There is, however, good ground for supposing 

 that the subject will be fully elucidated by chemical 

 enquiry. Those plants which seem most benefited by 

 its application, are plants which always afford it on 

 analysis. Clover, and most of the artificial grasses, con- 

 tain it, but it exists in very minute quantity only in 

 barley, wheat and turnips. Many peat ashes which 

 are sold at a considerable price, consist in great part 

 of gypsum, with a little iron, and the first seems to 

 be their most active ingredient. I have examined 

 several of the soils to which these ashes are success- 



D 



