VI. 



MANURING AND GENERAL MANURES 



129 



showing the product to be rich in manurial ingredients. The 

 nitrogenous matter doubtless consisting largely of chitin, the horny, 

 external skeleton of the insects would probably be somewhat slow 

 in decomposing in the soil, but despite this, locusts should form a 

 valuable manure. In the Argentine, in 1899, they gave excellent 

 results when mixed with superphosphates. 



Even when the carcasses of animals are incinerated (e.g., with a view 

 of preventing the spread of contagion during the prevalence of a disease) 

 and the organic nitrogenous matter thus mainly destroyed, the ash left 

 is possessed of considerable manurial value. 



A product obtained from a Veterinary Bacteriological Station, 

 where the bodies of the animals used were thus disposed of, was found 

 by the writer to contain 



Moisture 



1 Loss on ignition 

 Insoluble matter 

 Iron oxide 

 Lime . 

 Magnesia 

 Potash 

 Phosphorus pentoxide 

 Undetermined 



Containing nitrogen 



1-30 

 13-09 

 13-78 



5-17 

 35-23 



0-66 



1-48 

 28-16 



1-04 



100-00 

 1-27 



Evidently, from the occurrence of organic matter and nitrogen, the 

 combustion of the bodies had not been complete. Probably the amount 

 of iron oxide was increased in consequence of the presence of iron shoes 

 and nails, for the carcasses employed were chiefly those of horses and 

 mules. 



Soot. The soot collected from the imperfect combustion of coal 

 contains a portion of the nitrogen of the coal in the form of ammonium 

 salts and as organic nitrogenous compounds of an amine character. 

 Its usefulness as a manure depends upon the nitrogen which it con- 

 tains ; this varies from very little up to 3 or 4 per cent ; on an average 

 perhaps 1-8 or 2 per cent will be present. Soot is useful as an in- 

 secticide. 



It also has a value in increasing the absorptive power of the soil 

 for the heat rays of the sun and it has been found that, in bright sun- 

 light, a soil may rise two or three degrees in temperature from the 

 application of a thin sprinkling of soot. It also tends to render a heavy 

 soil more friable and porous, by virtue of the coal-ashes which are pre- 

 sent in nearly all samples of soot. Its action as an insecticide is partly 

 due to the ammonium salts, partly to the sulphur compounds and 

 partly to the tarry constituents which it contains. 



The composition of soot varies greatly ; factors which most power- 

 fully affect its character are draught of flue, height in the chimney 

 from which the sample was collected, character of fuel and manner of 

 stoking. 



9 



