790 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



not drive the ammonia therefrom, because as just indicated, there is 

 very little in it. As soon, however, as decomposition sets in, evolr- 

 ing ammonia from the nitrogenized matter, and producing organic acids 

 from the wood}' or carbonaceous substance of the manure, or of the 

 muck, as the case may be, the lime unites with the acids and usurps 

 the place of the ammonia, so that the latter passes into the air and i« 

 lost. From this has come the common sense precept, " never mix 

 lime with nitrogenized manures of any kind." With regard to the 

 sulphate of lime or gypsum, however, it is very different. This sul)- 

 stance has the power, not quite understood and never fully explained 

 even by the oldest and best chemists, of fixing or retaining ammonia. 

 For this reason it maj' be used to advantage in the compost to help as far 

 as may be the decomposing muck to collect and retain the ammonia as 

 fast as generated. Yet it must not be supposed that the retention of the 

 ammonia is wholly due to the organic acids above mentioned, for this 

 is not the case. The muck particles possess a very great power of 

 mechanically absorbing ammonia, when wet frequently as much as 

 two per cent, and of this when dried at ordinary temperature it 

 retains from one-half to three-fourths. ISTeither must it be supposed 

 that the acids of the decaying peat have no other function than to 

 unite with the ammonia. A portion of these acids unite with the 

 other alkalies, soda, potash and lime, liberated from their original 

 combinations in the manui'e. These several ultimates of ammonia, 

 potasli, etc., all have a dark brown color. This may be kept in mind 

 by the farmer who allows the rain to saturate his dung-heap, and 

 run thence in a chestnut colored stream to the nearest ravine. 



At the outset of this article it was remarked that one of the objects 

 of composting is to bring the various components of manure into that 

 condition in which they will prove the most beneficial to vegetation. 



This is secured, firstly by the retention and utilization of both the 

 liquid and solid elements of the manure ; and secondly, bj the con- 

 version of the nitrogenized components of the latter into ammonia, 

 either combined with organic acids or held mechanically absorbed in the 

 muck itself, but in either case readily assimilable by the roots of plant* 

 as soon as mingled with the mold and subjected to the action of the 

 themical agencies at work in the soil and the vital functions of vege- 

 tation. A numure made and managed in this way will come the nearest 

 of any to a truly universal manure, inasmuch as all the elements of 

 the plants eaten by tlie animal are contained in it in the very form 

 best adapted, when mingled with the soil, to enter into a com])osition 



