PRACTICAL INFERENCES. 285 



** When the excrements of the horse or ox are employed, 

 we are obliged to allow of their undergoing a long previous 

 process of fermentation, by which a large proportion of their 

 valuable matter is got rid of, in order, as much as possible, 

 to destroy the vitality of the seeds, which pass undigested 

 along with the faeces. And after all many still remain, 

 and are thus introduced into the fields when the manure is 

 scattered over them. 



'*By the use of night-soil we avoid this inconvenience, 

 and hence it is, that in China, where it is exclusively em- 

 ployed, the corn-fields are remarkably exempt from weeds. 



'* Chemistry has suggested means for destroying those 

 offensive qualities which have hitherto limited the use of 

 this species of manure, although it is stated by Liebig, 

 that the method adopted for that purpose on the Continent 

 is defective, inasmuch as a large proportion of their am- 

 moniacal contents is allowed to escape. 



*' Even under its present management, however, the pro- 

 cess may be regarded as one of the most important pres- 

 ents which chemistry has yet made to the practical farmer, 

 by rendering the accumulated filth of a large capital avail- 

 able for his purposes, in the remotest corner of the British 

 empire." 



Professor Daubeny concludes his lecture with some high- 

 ly ingenious speculations on the primary source of the 

 carbon and nitrogen present in plants and animals. He 

 does not deem it probable that a quantity of organic 

 matter was called into existence at once, sufficient to sup- 

 ply the whole of the succeeding races of plants and ani- 

 mals with these ingredients ; or that the whole, which is 

 now condensed in the organization of the animal and vege- 

 table kingdoms, was at any one time present in the atmo- 

 sphere ; but that the carbon and nitrogen of plants was 

 originally supplied from the interior of the earth by vol- 

 canos. The fertility of the neighborhood of Naples Dr. 

 D. attributes to volcanic exhalations. 



"Once grant," he continues, "with Liebig, that the 

 nitrogen, which plants possess, can only be obtained by 

 them through the decomposition of ammonia, and it will 

 follow, that unless this gas be supplied from the interior of 

 the globe, the quantity of organic matter, into which this 

 principle enters as a component part, will be undergoing 

 a continual diminution. 



"For we know of no natural processes taking place on 

 the surface of the globe, which generate ammonia, ex- 



