Xitrate of Soda as a Manure. 



The success therefore of the experiment was complete. The ques- 

 tion being vvhether in saltpetre the alkalies or the acid contain the 

 active principle, v;e have found upon a given soil the alkalies abso- 

 lutely inoperative, v hile the acid has acted exactly like saltpetre 

 itself and like ammonia. The action, indeed, does not follow anj 

 precise proportion to the quantity of nitric acid employed, but 

 neither does it to the quantity of saltpetre. For both, as is 

 the case with other manures, there is no doubt a maximum, to 

 exceed which is useless and may even be prejudicial. But the 

 action of the nitric acid w'as palpable, unfailing, and indeed 

 very powerful. On many other parts of the grass-plot sprinklings 

 of the diluted acid were poured, and were everywhere followed by 

 a dark luxuriant vegetation. We may now^ therefore assume, with 

 unhesitating certainty, as a great law of nature, that substances 

 streiig'tlieii Teg-etation saainiy by tlieir contents ©f nitrog-en. 



This law sheds at once an harmonious light over the scattered 

 facts which the unlettered husbandman has learned while still 

 groping in the darkness of practice. If we look at the practice of 

 mamiiing only, we find the most dissimilar substances applied to 

 the soil — sprats or sticklebacks here ; woollen rags, or shoddy, 

 or hornshavings there ; seaweed in another place, rapecake else- 

 where. All these refuse matters, however, agree in containing 

 undeveloped Xitrogen. Again, lupines, sow^n for the purpose, are 

 in some countries ploughed in as manure, as are the remains of 

 the clover-crop, both also containing Nitrogen undeveloped. In 

 dung and in liquid manure the nitrogenous matter is partly com- 

 bined with hydrogen, and has thus become ammonia. In other 

 manures, as soot and gas-water, the pungent smell shows the 

 full development of ammonia. Again Nitrogen may combine not 

 only with hydrogen to form an alkali, ammonia, but with 

 oxygen also to form an acid. That acid, in whatever combina- 

 tion, whether with potash, soda, or lime, is equally active ; nay, 

 as I have now shown, the consuming liquid itself is able to nourish 

 the tender herbage of the green lawn. This same law explains 

 moreover not fertilizing substances alone, but the fertility of the 

 soil itself also throughout many wide tracts. Not only are the 

 plains of Hindostan made fruitful by their native saltpetre, but the 

 famous Tchornoi Zem, or black earth, which over wdde tracts 

 around Tamboff bears wheat crops in endless succession, and 

 will not endure to be dressed with dung, has been found by late 

 analysis* to be charged with nitrogenous matter, the remains 

 of living organisms. Nay, when poetsf tell us that battle-fields 



* See Payen's analysis in Sir E. Murcliison's account of the Tchornoi Zem, 

 Journal iii. 132". 



+ Nec fuit indignum superis bis sanguine nostro 

 Emathiam et latos Hsemi pinguescere campos." 



Emathia, 



