

1819.] upon Animal and Vegetable Substances. 12? 



months, and probably for a far longer period, when most vege- 

 tables were consumed completely in half that time. These 

 facts will, however, lead us to a few results at present, as well as 

 to future trials, and will enable us to explain and reconcile the 

 opinion of many excellent agriculturists and chemists. It will 

 also show why certain processes have always uniformly agreed 

 and been advantageous when pursued. This may be the reason 

 why lime so admirably (when enclosed with bog earth where it 

 has first to reduce the undecayed vegetable matters, such as the 

 limbs of trees and hard roots) decomposes plants so quickly and 

 corrects the acid of the more decayed vegetable matter in bogs 

 of older formation. It will also explain how completely possible 

 it is in a piece of boggy heath, overrun with the heathy plants, 

 to bring the ground into a perfect state of agricultural order and 

 beauty in a short time, by the application of repeated quantities 

 of lime freshly turned in. As hard as the roots are, a few months 

 will, it seems, entirely decompose and reduce them to a black 

 powder, which must of course be a fine manure, when lime is 

 added to correct the acid, proceeding thence from the decom- 

 posed vegetable matter, as that vegetable matter first forms a 

 powder and thick black liquid. 



I have now placed the same collection of vegetables and 

 boughs of trees in another trough to try the experiment once 

 more, rendering the lime rather milder ; while I am also adding 

 another trench, with a mixture of half lime and half earth, to try 

 their joint effects on vegetable matter, that I may ascertain 

 whether the destruction of the vegetable is caused by the passing 

 of quick lime into mild lime, or whether it depends immediately 

 on the action of mild lime only on vegetable matter. Sir H. Davy 

 says, in his admirable work on agriculture, that quick lime only 

 improves certain soils, and that in the act of becoming mild ; 

 that is, in passing from pure to carbonate, it prepares soluble out 

 of insoluble matters. Now the lime that I placed with both the 

 animal and vegetable matter was exactly the same, equally slaked, 

 and sufficiently so to be in fine powder. It is certain, however, 

 that in that state it has not lost all its corroding power ; for if 

 water be thrown on it much heat is extricated ; perhaps, by 

 having decomposed the wood while in its first and most active 

 state it was more easily completed by an after process, though 

 no longer possessing any acid property. 



But if it be by its heating or corrodingquality, how comes it that 

 it does not affect the animal as well as vegetable matter ? There 

 was quite lime enough to surround the plants in the same manner 

 as the meat, since it lay on the boughs veiy thick ; and though 

 the bark immediately decayed, in no one instance did the lime 

 collect round the plants, or coagulate around the stem. But to 

 answer Sir H. Davy's question, whether it be the passage from 

 quick lime to mild lime that effects the purpose of decomposition 



