SOOT. 283 



improper for irrigation, until they have deposited the slime which 

 they hold in suspension ; the waters are therefore turned into canals 

 for the purpose of deposition before they are let upon the land ; and 

 such is the quantity of slime that is precipitated, that two or three 

 gatherings of it are made in the course of the year. It is dug out 

 and thrown upon the banks to dry ; reduced to powder, it is fit to be 

 laid upon the land ; and such is its fertilizing power, that a field 

 which yielded but four for one, has been brought to yield twelve for 

 one by its means.* 



Wood and coal soot, and Picardy ashes. Soot has been known 

 tor a long period as a useful manure. M. Braconnot, in the soot of 

 a chimney where wood had been the fuel, found the following in- 

 gredients : 



Ulmicacid 30.0 



Azotic matter, soluble in water 20.0 



Insoluble carbonated matter 3.9 



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 of potassium 0.4 



Acetate of potash 4.1 



Acetate of lime 5.7 



Acetate of 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 



The analysis which M. Payen and I made of wood and coal soot, 

 confirms the presence of the azotized principle detected by M. Bra- 

 connot. A considerable trade is carried on in soot for agricultural 

 purposes in large towns ; it is thrown upon clovers and young wheats, 

 in the proportion of about 20 bushels lo the acre. Some have re- 

 commended that it should be mixed with lime ; but as soot always 

 contains salts having a base of ammonia, the practice is evidently 

 objectionable, unless indeed the object be to get rid of that which is 

 most useful in the article, which will be effectually accomplished by 

 adding lime to it. The proper procedure is to employ the soot 

 without admixture during calm or wet weather. In Flanders, the 

 colewort beds destined for transplanting are very generally manured 

 with soot, which is believed to have the property of preserving the 

 young plants from the attacks of insects. In the neighborhood of 

 Lisle, they give from 55 to 60 bushels of soot per acre. Schwertz 

 appeals to many facts which go far to satisfy us that the eflfects of 

 soot upon clovers are particularly advantageous ; he says, moreover, 

 that coal soot is preferable to wood soot. The superior properties 

 of coal soot are evidently due to two causes : first, it is more dense 



* Belleval, in Annals of French Agriculture,«2d series, vol. xiv. p. 261. The beds of 

 many of the oozy-bottomed rivers in England near the sea are inexhaustible sources 

 of the most valuable manure. The bed of the Thames, between London Bridge and 

 Putney Bridge at low wau;r, ii; a true i,(^\t\ mine if it were but richtly used. — Eno. Ed 



