THE NITROGEN THEORY. 279 



nitrogen was the reason of activity, so in the other case 

 the want of nitrogen caused the want of activity ; in 

 short, by the operation of nitrogen all facts seemed to 

 be harmonised and explained. 



If the nitrogenous manures depended for their ac- 

 tivity upon the nitrogen which they contained, it fol- 

 lowed necessarily that all of them could not possess the 

 same value for the farmer, because they did not all 

 contain the same amount of nitrogen ; those which had 

 more of this substance were manifestly more valuable 

 than those which had less. The amount of nitrogen 

 was easily determined by chemical analysis ; hence 

 arose the idea to draw up for the benefit of farmers a 

 list of manures with a figure attached to each showing 

 its relative value ; those which were most abundant in 

 nitrogen were considered the most valuable, and stood 

 highest in the list. 



In this valuation no importance was attached to the 

 form which nitrogen assumed in the various manures, 

 and just as little to the substances which were present 

 along with the nitrogenous compound. In this list it 

 was quite immaterial whether the nitrogenous combina- 

 tion was in the form of gelatine, horn, or albumen ; or 

 whether these substances were or were not accompa- 

 nied by earthy or alkaline phosphates. Dried blood, 

 claws, horn shavings, woollen rags, bones, rape-cake 

 meal, all figured in one and the same list. 



As no definite combination was understood by the 

 word ' nitrogen,' it was impossible to prove that the 

 operation of nitrogenous manures bore any proportion 

 to the amount of nitrogen which they contained. 



The introduction and application of Peruvian guano 

 and nitrate of soda afforded the so-called nitrogen the- 

 ory a foundation to rest upon ; no manure could be 

 compared with guano for abundance of nitrogen, while 

 it surpassed all others in the rapidity and strength of 

 its action. The powerful effect produced by it coin- 

 cided entirely with the nitrogen theory ; it correspond- 

 ed with the high amount of nitrogen in the manure, 

 and chemical analysis furnished satisfactory conclusions 



