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THE GENESEE FARMER. 20T 



seized upon this discovery as one that affords strong evidence of a practical nature that 

 their theory is correct : hence they exultingly say, " Here, in this discovery, we have 

 the cause explained of the well known value of soot for agricultural purposes." 



It is a " well known" fact that soot is of great value for agricultural purposes ; espe- 

 cially is it found a valuable manure for wheat and other cereals, and sells for this 

 purpose in the English towns at from twelve to twenty cents per bushel. Dr. Anderson 

 says of it : " I have used soot as a top-dressing for clover and rye grass, in all propor- 

 tions from one hundred bushels per acre to six hundred, and I can not say that I ever 

 could perceive the clover in the least degree more luxuriant than in the places Avliere no 

 soot had been applied ; but upon rye grass its effects are amazing, and increase in pro- 

 portion to the quantity, so fjir as my trials have gone." And his general conclusion is, 

 " that soot does not affect the growth of clover in any way, while it wonderfully promotes 

 tKut of rye grass. ^^ 



But we need not quote experiments, for it is universally admitted to be a most pow- 

 erful and efficacious manure for all cereal crops. And this fact, — if it were true that 

 the soot generally used for agricultural purposes contained 40 per cent, of potash — 

 would indeed be a most potent argument in fivor of the mineral theory ; but this is not 

 the case. A sample of soot analyzed by M. Braconnot, taken from a chimney where 

 wood had been the fuel, was found to contain the following ingredients : 



TJlmic acid, 30.0 



Nitrogenous matter, soluble in water, 20.0 



Insoluble carbonated matter, 8.9 



Silica, 1.0 



Carbonate of lime, 14.7 



Carbonate of magnesia, (traces of.) 



Sulphate of lime, 0.5 



Ferruginous phosphate of lime, 1.5 



Chloride ol potassium, 0.4 



Acetate of potash, 4.1 



Acetate of lime, 5.7 



Acetate ot magnesia, 0.5 



Acetate of iron, (traces of.) 



Acetate of ammonia, 0.2 



An acrid and bitter element, 0.5 



Water, 12.5 



100.0 



This analysis is also confirmed by M. Payen and M. Boussingault. The latter, speak- 

 ing of the soot from coal, says : " The superior qualities of coal soot are evidently due 

 to two causes : first, it is more dense than wood soot, and in a given bulk actually con- 

 tains a greater amount of matter. Secondly, I have found that for equal weights coal 

 soot contains the larger quantity of nitrogen.'''' 



There can, we think, be little doubt that the good effects of soot as a manure are 

 owing to the large amount of nitrogen and ammonia it generally contains. There 

 is, however, a dift'erence in the composition of soot, owing, it is thought, principally to 

 the draught and the height of the chimney — the soot from a high chimney being con- 

 sidered the best, and it actually sells for half as much again as the soot from a low 

 chimney. Is not this owing to the fiict that the inorganic matter (the potash, lime, 

 soda, <fcc.,) is merely carried up the chimney mechanically by the draught, and settles 

 much sooner on the sides of the chimney than the organic matter, (nitrogen, &c.;) so 

 that the higher the chimney the richer would be the soot in nitrogen, and the more 

 valuable ? 



The analysis of Dr. Penny is doubtless correct, but it by no means represents the 

 composition of the soot generally used for agricultural purposes. The intense he?t and 

 draught (an immense pair of bellows worked by a steam engine is usually employed to 

 create the blast) probably sublimates the potash, and the draught carries it up the 

 chimney, where it would lodge on any protuberance ; and the position in which the 

 soot examined by Dr. Penny was found favors this idea. 



