64 



AGRICULTURAL CHEMISTRY. 



advantageous for other soils also; but for 

 tne manure of those first mentioned, the ex- 

 crements of other animals are quite indis- 

 pensable. 



OF URINE. 



We possess only one other natural source 

 of manure which acts by its nitrogen, be- 

 sides the faeces of animals, namely, the 

 urine of man and animals. 



Urine is employed as manure either in 

 the liquid state, or with the fasces which 

 are impregnated with it. It is the urine 

 contained in them which gives to the solid 

 faeces the property of emitting ammonia, a 

 property which they themselves possess only 

 in a very slight degree. 



When we examine what substances we 

 add to a soil by supplying it with urine, we 

 find that this liquid contains in solution am- 

 moriiacal salts, uric acid (a substance con- 

 taining a large quantity of nitrogen,) and 

 salts of phosphoric acid. 



According to Berzelius 1000 parts of hu- 

 man urine contain: 



Urea 30'10 



Free Lactic acid, Lactate of Ammonia, and 



animal matter not separable from them 17*14 



Uric acid 1 00 



Mucus of the bladder - 0'32 



Sulphate of Potash .... 3'71 



Sulphate of Soda .... 3'16 



Phosphate of Soda 2'94 



Phosphate of Ammonia 1'65 



Chloride of Sodium .... 4-45 



Muriate of Ammonia - - - . 150 



Phosphates of Magnesia and Lime - TOO 



Silicious earth 0'03 



Water 933'00 



100000 



If we subtract from the above the urea, 

 lactate of ammonia, free lactic acid, uric 

 acid, the phosphate and muriate of ammo- 

 nia; 1 per cent, of solid matter remains, 

 consisting of inorganic salts, which must 

 possess the same action when brought on a 

 field, whether they are dissolved in water or 

 in urine. Hence the powerful influence of 

 urine must depend upon its other ingredients, 

 namely, the urea and ammoniacal salts. 

 The urea in human urine exists partly as 

 lactate of urea, and partly in a free state. 

 (Henry.) Now when urine is allowed to 

 putrefy spontaneously, that is, to pass into 

 that state in which it is used as manure, all 

 the urea in combination with lactic acid is 

 converted into lactate of ammonia, and that 

 which was free, into volatile carbonate of 

 ammonia. 



In dung- reservoirs well constructed and 

 protected from evaporation, this carbonate 

 of ammonia is retained in the state of solu- 

 tion, and when the putrefied urine is spread 

 over the land, a part of the ammonia will 

 escape with the water which evaporates, 

 but another portion will be absorbed by the 

 soil, if it contains either alumina or iron; 

 but in general only the muriate, phosphate, 

 and lactate of ammonia remain in the 



ground. It is these alone, therefore, which 

 enable the soil to exercise a direct influence 

 on plants during the progress of their growth, 

 and not a particle of them escapes being ab- 

 sorbed by the roots. 



On account of the formation of this car- 

 bonate of ammonia the urine becomes alka- 

 line, although it is acid in its natural state. 

 When it is lost by being volatilized in the 

 air, which happens in most cases, the loss 

 suffered is nearly equal to one half of the 

 weight of the urine employed, so that if we 

 fix it, that is, if we deprive it of its volatility, 

 we increase its action two-fold. The exist- 

 ence of carbonate of ammonia in putrefied 

 urine long since suggested the manufacture 

 of sal-ammoniac from this material. When 

 the latter salt possessed a high price, this 

 manufacture was even carried on by the 

 farmer. For this purpose the liquid obtained 

 from dunghills was placed in vessels of iron, 

 and subjected to distillation; the product of 

 this distillation was converted into muriate 

 of ammonia by the common method. (De- 

 machy.) But it is evident that such a 

 thoughtless proceeding must be wholly re- 

 linquished, since the nitrogen of 100 Ibs. of 

 sal-ammoniac (which contains 26 parts of 

 nitrogen) is equal to the quantity of nitrogen 

 contained in 1200 Ibs. of the grain of wheat, 

 1480 Ibs. of that of barley, or 2755 Ibs. of 

 hay. (Boussingault.) 



The carbonate of ammonia formed by the 

 putrefaction of urine, can be fixed or de- 

 prived of its volatility in many ways. 



If a field be strewed with gypsum, and 

 then with putrefied urine or the drainings 

 of dunghills, all the carbonate of ammonia 

 will be converted into the sulphate which 

 will remain in the soil. 



But there are still simpler means of effect- 

 ing this purpose ; gypsum, chloride of cal- 

 cium, sulphuric or muriatic acid, and super- 

 phosphate of lime, are all substances of a 

 very low price, and completely neutralise 

 the urine, converting its ammonia into salts 

 which possess no volatility. 



If a basin, filled with concentrated mu- 

 riatic acid, is placed in a common necessary, 

 so that its surface is in free communication 

 with the vapours which rise from below, it 

 becomes filled after a few days with crystals 

 of muriate of ammonia. The ammonia, the 

 presence of which the organs of smell amply 

 testify, combines with the muriatic acid and 

 loses entirely its volatility, and thick clouds 

 or fumes of the salt newly formed hang over 

 the basin. In stables the same may be seen. 

 The ammonia that escapes in this manner 

 is not only entirely lost, as far as our vegeta- 

 tion is concerned, but it works also a slow, 

 though not less certain destruction of the 

 walls of the building. For when in contact 

 with the lime of the mortar, it is converted 

 into nitric acid, which gradually dissolves 

 the lime. The injury thus done to a build- 

 ing by the formation of the soluble nitrates, 

 has received (in Germany) a special name 

 salpeterfrass. 



