438 COMPOSITION OF SOOT — ITS EFFECTS UPON RYE-GRAS3. 



Ulmic acid ? (a substance resembling that portion of the 

 vegetable matter of the soil which is soluble in caustic 



potash— (see Lee. XIII., § 1) 302-0 



A reddish brown soluble substance, containing nitrogen, and 



yielding ammonia when heated 200-0 



A sboline 5-0 



Carbonate of lime, with a trace of magnesia (probably de- 

 rived in part from the sides of the chimney) 146-6 



Acetate of lime 56-5 



Sulphate of lime (gypsum) 50-0 



Acetate of magnesia , 5-3 



Phosphate of lime, with a trace of iron 15-0 



Chloride of potassium 3-6 



Acetate of potash 41-6 



Acetate of ammonia 2-0 



Silica (sand). 9-5 



Charcoal powder 38*5 



Water 125-0 



1000* 



The earthy substances which the soot contains are chiefly derived 

 from the walls of the chimney, and from the ash of the coal, part of 

 which is carried up the chimney by the draught. These, therefore, 

 must be variable, being largest in quantity where the draught is strong- 

 est and where the earthy matter or ash in the coal is the greatest. The 

 quantity of gypsum present depends upon the sulphur contained in the 

 coal,— that which is freest from sulphur will give a soot containing the 

 least gypsum. The ammonia and the soluble substances containing ni- 

 trogen will vary with the quantity of nitrogen contained in the coal and 

 with certain other causes — so that the composition of different samples 

 of soot may be very unlike, and their influence upon vegetation there- 

 fore very unequal. The consequence of this must be, that the results 

 obtained in one spot or upon one crop, are not to be depended upon, as 

 indicative of the precise effect which another specimen of soot will 

 produce in another locality, and upon another crop even of the same 

 kind. And thus it happens that the'use of soot is more general, and 

 is attended with more beneficial effects, in some districts than in others. 



a. In general it may be assumed that where ammonia or its salts 

 will benefit the crop, soot also will be of use, and hence its successful 

 application to grass lands. From its containing gypsum it should also 

 especially benefit the clover crops. Yet Dr. Anderson says, " I have 

 used soot as a top-dressing for clover and rye- grass in all proportions, 

 from one hundred bushels per acre to six hundred, and I cannot say 

 that ever I could perceive the clover in the least degree more luxuri- 

 ant than in the places where no soot had been applied. But upon 

 rye-grass its effects are amazing, and increase in proportion to the 

 quantity so, far as my trials have gone." (Dr. Anderson's Essays, 

 edit. 1800, ii., p. 304.) And his general conclusion is, that soot does 

 not affect the growth of clover in any way. while it wonder/idly promotes 



* Annales de Chcmie et de Physigtie, xxxi., p. 37. 



