PAKMYAKD MANURE. 19- 



six months, and that during this period the total amount of 

 nitrogen scarcely suffered any diminution. In April the amount 

 of nitrogen in the soluble matters of the entire heap is 6*07 Ibs., 

 and by the 23rd of August it is reduced to 3'76 Ibs. Why, it 

 it may be asked, is it not likely that most of this nitrogen has 

 passed into the air in the form of volatile ammoniacal com- 

 pounds ? In reply to this question, I would answer that a loss 

 taking place in this way would be felt much more sensibly in 

 the period of active fermentation, in which, however, we have 

 seen that scarcely any nitrogen is dissipated. In the August and 

 November analyses, moreover, it will be observed that not only 

 the amount of soluble organic matters, and with it that of the 

 nitrogen, decreases, but that the soluble mineral matters, which 

 in April amount to 57*88 Ibs. in the entire heap, became reduced 

 to 39vl6 Ibs. by the 23rd of August. Now, this decrease in 

 soluble mineral substances can only be ascribed to the rain 

 which fell in this period, and it is plain that the deteriorating 

 influence of heavy showers of rain must equally affect the soluble 

 nitrogenized constituents of dung. 



It may perhaps appear strange that the total amount of dry 

 matter in the manure is greater in November, 1855, than in 

 August, and likewise that there is a good deal more insoluble 

 mineral matter at the end of the experimental year than at the 

 beginning. In explanation of these apparent inconsistencies, I 

 would observe that the increase in insoluble mineral matters is 

 accounted for in the difficulty of shovelling the manure into the 

 dung-cart without mixing with it each time the weighing is made 

 a certain portion of the soil on which the heap is placed. It 

 must likewise be borne in mind that it is almost next to impos- 

 sible to incorporate mechanical impurities so thoroughly with 

 the dung that differences amounting to 2 or 3 per cent, in the 

 amount of insoluble matters may not occur in the analyses of 2 

 samples taken from the same heap. In the percentic composition 

 of farmyard manure such differences appear inconsiderable, but 

 when applied to the whole heap they strike us as being great. 

 In short, it is impossible to determine accurately the total amount 

 of insoluble mineral matters in the whole heap. The general 

 deductions, however, which may legitimately be made from the 

 foregoing analyses are not in any perceptible degree affected 

 by this unavoidable source of inac curacy ; but it is well to 

 remember not to dwell too much on minor differences which 

 perhaps may strike the reader ; some such differences may be 

 due to purely accidental causes. 



