THE 



GARDENER'S MAGAZINE, 



JULY, 1841. 



ORIGINAL COMMUNICATIONS. 



Art. I. On the Philosophy of Manures. By R. Lymburn. ; 



Since sending you the essay on Dr. Liebig's Physiology applied 

 to Agriculture, I have seen the different publications of Professor 

 Daubeny of Oxford and Professor Johnstone of Durham on 

 the same subject. The philosophy of manures seems to have 

 attracted the attention it so deservedly merits ; and, when 

 brought so prominently forward by men who, notwithstanding 

 their profound knowledge of theory, are yet so cautious as to 

 wish every thing confirmed by actual experiment, we may well 

 anticipate great results. The experiments instituted by Professor 

 Daubeny, and those pointed out by Professor Johnstone as 

 proper to be conducted by agriculturists themselves, should 

 greatly help to enable theory to point out the true action taking 

 place in the conversion of the various substances exhibited as 

 manures into the food of the plant. Having already occupied so 

 much room in your valuable periodical (p. 97.), I will confine 

 myself in the present essay to the notice of those subjects not 

 previously brought forward by Dr. Liebig, or on which the 

 above professors seem not perfectly agreed. 



On the subject of Ammonia, Professor Daubeny remarks 

 that, if we confine its source to that furnished by animals to 

 plants, and if the plants which have furnished it to animals 

 derived it from the atmosphere, either a superabundance must 

 have originally existed in the atmosphere, and would, in that 

 case, have been fatal to the then smaller quantity of plants, or 

 there must be some other source of supplying the want of 

 ammonia which increased population, and, consequently, cultiva- 

 tion, have rendered necessary. This source he considers volcanic; 

 and that ammonia is formed by that combustion in the bowels of 

 the earth, which is inferred from the observed escape of air 

 from the earth, deprived of part of its oxygen. Water thus 

 decomposed in the earth will yield both oxygen and hydrogen ; 

 the former of which uniting to carbon will form carbonic acid ; 

 and the latter, or hydrogen in its free nascent state (as hydrogen 

 and nitrogen unite most freely when newly set free), unites to 



1841. — VII. 3d Ser. z 



