472 ANNUAL REPORT OF THE Off. Doc. 



tory. It was found that the treatment with acid of (he strength used 

 in the fertilizer factory, destroyed with practical completeness, the 

 ti.ssues of these materials, so that they wore no longer recognizable 

 under tiie microscope. 



The treatment increased the water-sol iibility of the nitrogen greatly 

 in every case. In the original materials the percentage of the total 

 nitrogen that could be dissolved by water ranged from none in the 

 fresh Iiaii- and sole leather to l.'M4 per cent, in the rotted hair and 

 slightly fermented horn meal ; but after treatment, the water soluble 

 portion ranged from 40 to 78 per cent, of the total nitrogen present. 



Furthermore, while of the total nitrogen present as ammonia in 

 the original materials the quantity ranged from but 0.1 per cent, 

 in sole leather to G.l per cent, in rotted hair, in the acid treated 

 materials the proportion of ammonia nitrogen to the total nitrogen 

 ranged from 1.7 to 14.1 per cent. The increase was, therefore, very 

 considerable, but not sufticient to warrant the manufacturer in say- 

 ing, as he often does, "The process converts the nitrogen to ammonia." 

 For clearly, most of the nitrogen remains after the acid treatment in 

 an organic condition. 



It is well known that most organic materials used as fertilizers 

 must, before they can be taken up by the plants, be converted into 

 ammonium salts and especially into nitrates, and that these changes 

 are etlected in the soil to varying degrees with different materials 

 by the help of certain soil bacteria. It is needful to know concern- 

 ing these nitrogenous products, how they respond to the attack of 

 these bacteria. 



The experiment included, therefore, a study upon this point. It 

 was found that, in our soil, taken from the Station farm in a mildly 

 acid condition, the nitrogen of the original soft leather, wool waste, 

 and garbage tankage did not experience any change what ever to 

 ammonia in the course of seven days, the duration of our test ; but 

 that of the nitrogen of the horn meal, 12.67 per cent., and that of 

 the rotted hair, 1.5.29 per cent., appeared as ammonia at the end 

 of this time, the other materials remaining intermediate between 

 these extremes; whereas, a good sample of dried blood showed 19.44 

 per cent, of its nitrogen as ammonia after the test. In the acid- 

 mixed materials, on the other hand, the proportion of ammoniacal 

 nitrogen ranged from 19.6 per cent, in the garbage tankage to 84.95 

 per cent, in the hoof-scrap. In like manner, the nitrification test, 

 continued for five weeks, showed in case of every material upon 

 which it was tried a large increase of nitrification in case of the 

 acid-treated as compared with the corresponding raw nitrogenous 

 substance. 



Finally, these laboratory tests were followed by a field test of 

 the effect of the fertilizers, before and after acidulation, upon rye. 

 These field tests were so affected by a mechanical source of error 

 that I do not feel that dependence can be placed upon their indi- 

 cations with respect to the individual nitrogenous materials. By 

 confining the attention simply to a comparison of the group of ma- 

 terials under test, the disturbing effect of this source of error 

 are largely elminated. 



