THE FARMER'S MAGAZINE. 



377 



more, but sUU a very inconsiderable quantity of 

 free ammonia. Thus under the most favourable 

 circumstances 100,000 parts of horse-dung yield 

 only 49 parts of free ammonia; or in other words 

 40 tons in round numbers yield, on long-continued 

 boiling, 49 lbs. of ammonia. It must not be 

 supposed, however, that this quantity of ammonia is 

 dissipated into the air during the fermentation of the 

 dung, for it is only in the interior of the dung- 

 heap that ammonia is liberated. It is, indeed, only 

 on turning a heap that ammonia escapes at all, in 

 any perceptible degree ; but as soon as the external 

 layers have become cooled down to the ordinary 

 temperature of the air, its escape is arrested. There 

 can, therefore, be not the slightest doubt that but a 

 very minute quantity of ammonia passes into the air, 

 and the remainder is fixed in the heap, provided 

 the heap is kept in such a manner that rain cannot 

 remove from it much of the soluble matters, and 

 with them ammoniacal salts. 



"The strong smell which is observed, on turning 

 a dung-heap, no doubt has led many greatly to 

 over-estimate the amount of ammonia which 

 escapes from farm-yard manure in an active state 

 of fermentation. But I would observe that no- 

 thing is more fallacious than the estimation of the 

 amount of ammonia by the pungency of the smell 

 which is given off from fermenting animal matters. 

 Such matters often give off a very powerful smell, 

 which is due to peculiar volatile organic combina- 

 tions — to some sulphuretted and phosphoretted 

 hydrogen and a great variety of gaseous matters, 

 amongst which there is ammonia gas in very minute 

 quantities. The smell of this highly comphcated 

 and but scantily examined mixture of gaseous 

 matters as a whole is ascribed by the popular mind 

 to ammonia. From these products of putrefaction, 

 however, ammonia can be completely separated, 

 without in the least destroying the peculiar offensive 

 smell which emanates from organic matters in a 

 state of decomposition. If, for instance, dilute 

 sulphuric acid is added to farmyard manure or 

 liquid manure, the smell of these substances, in- 

 stead of becoming neutralized by the acid, in reality 

 becomes more offensive. This arises in great 

 measure from the liberation of sulphuretted hydro- 

 gen. Hence acids are not well adapted for disin- 

 fecting cesspools or nightsoil. As di'ute sulphuric 

 acid neutrahzes instantly feer ammonia, form- 

 ing with it an inodorous salt, which is not volatile 

 at the ordinary temperature, it is evident that the 

 foetid smell of putrefying matters has much less to 

 do with ammonia than is generally believed." 



We see then, fiora the result of such examination, 

 that in the preparation of dung, if the heat generated 

 is not excessive, that then the ammonia evolved is 

 far from being considerable. 



But if we have attended to this, if we have care- 

 fully prepared the dung, still another care then 

 arises, its preservation from rain, and consequent 

 impoverishment by drainage. Mr. Voelcker alludes 

 to the too frequent neglect of this precaution, when 

 he tells us that "in many places in England, especially 

 in Devonshire and in some parts of Gloucestershire, 

 it is a common practice to place manure-heaps by 

 the roadside, often on sloping ground, and to keep 

 these loosely-erected heaps for a considerable length 

 of time before carting the dung on the field. On 

 other farms, the manure is allowed to remain loosely 

 scattered about in uncovered yards for months be- 

 fore it is removed. Heavy showers of rainfalhng 

 on manure kept in such manner, by washing out 

 the soluble fertilizing constituents of dung, neces- 

 sarily greatly deteriorate its value. It is well-known 

 that the more or less dark-coloured liquids which 

 flow from badly-kept dung-heaps in rainy weather 

 possess high fertihzing properties. According to 

 the rain which falls at the time of collecting these 

 drainings, according to the character of the manure, 

 and similar modifying circumstances, the composi- 

 tion of the drainings from dung-heaps is neces- 

 sarily subject to great variations. The general 

 character of these hquids, however, is the same in 

 dilute and in concentrated drainings. Several 

 samples of dung-drainings were recently examined 

 by me, and, from their analyses, it will be seen that 

 they contain a variety of fertilizing constituents 

 which it is most desirable to retain in dung- 

 heaps. 



" According to the analytical results obtained in 

 these different determinations, an imperial gallon of 

 these drainings contained — 

 Volatile and combustible constituents 395*66 grams. 



Viz. :— 

 Ammonia driven out on \ 



boiling 36-25 /Together, 



Ammonia in the state of > 39'36 



salts decomposed by i 



quick lime 3" 11 J 



Ulmic and humic acid .. .. 125"50 

 Carbonic acid, expelled on 



boiling ... 88-20 



Other organic matters (contain- 

 ing 3*59 of nitrogen) 142-60 



395-66 



Mineral matters (ash) 368-98 grains. Viz. :— 

 Soluble silica .. • .• . •• I'^O 



Phosphate of lime, with a little 



phosphate of iron 15'81 



Carbonate of lime .. .. .. 34-91 



Carbonate of magnesia . . . . 25-66 



Sulphate of hme 4-36 



Chloride of sodium 45-70 



Chloride of potassium . . . . 70-50 



Carbonate of potash .. .. 170-54 



368-98 



Total per gallon in grains 



764-64 



D D 2 



