138 Observations on Lichig's " Organic Chemistry y 



carbonic acid from the woody fibre, which commences trans- 

 formation and fermentation ; but the carbonic acid that is united 

 to the Hme is rendered insohible and lost: it should not be ap- 

 plied to mixtures where there is much soluble matter, it is of 

 most use in commencing action where it is difficult, as in the 

 woody fibre. Heat and moisture, not wetness, should be en- 

 couraged as much as possible in all substances difficult to 

 reduce. Yeast, and all substances containing nitrogen, are 

 above all others valuable for continuing fermentation, which will 

 go on as long as nitrogen is to be found in the compound. 

 Sawdust of beech, ash, and other deciduous trees may be fer- 

 mented into manure: but sawdust from resinous fir trees is very 

 difficult to reduce: I have kept this and the scales of silver 

 fir cones for years to ferment, and got nothing soluble, unless a 

 few earthy salts: they are as manageable burnt as any other 

 way ; the ashes, the most that can be made available, are re- 

 tained. Tanner's bark, from the antiseptic principle of tannin 

 it contains, is also difficult to reduce, and requires some very 

 active fermenting substance, as yeast. It is the small quantity 

 of oxygen they contain, and the superabundance of hydrogen, 

 which must be separated before carbonic acid is formed, and 

 requires much more heat, that prevent their being made soluble; 

 and, though exposed to the oxygen of the air, the carbonic 

 acid is formed so slowly, that it is dissipated before it can be 

 made available. Alkalies mixed among fermenting substances 

 further the process of putrefaction greatly; acids retard it. Sea- 

 weed is exceedingly easily dissolved, and should be well mixed 

 with other substances, or put into the soil as soon as possible. 

 Soft animal matters, the refuse of slaughter-houses, &c., are also 

 very easily rendered soluble; both these and seaweed should 

 be well incorporated with strata of earth, and kept dry and 

 cool. 



Much has been said as to the application of dairy and 

 stable manure, whether it should be applied fresh or rotted. 

 Most of our theorists advise its application in a fresh, or un- 

 fermented, state ; most practical men are in favour of ro.tting. 

 In the Qiiarterly Journal of Agriculture, we had experiments 

 narrated a 'i^'^ years back, in which an intelligent practical agri- 

 culturist measured a certain quantity of manure, which he laid 

 past in a heap to rot; and at turnip-sowing he applied the rotted 

 heap, and the same bulk as the original quantity fresh, to equal 

 measured off portions of ground in the same field ; and the result 

 was a very great increase of crop with the rotted manure. Others 

 say their experience has led to a different result. Perhaps the 

 wisest course may lie in a medium. We have seen it incontest- 

 ably proved, by the experiments of Sir H. Davy and Dr. Liebig, 

 that carbonate of ammonia is given off, less or more, according 



