ECONOMY OF NITROGEK 



175 



small country towns, of villages and of detached 

 houses, where, theoretically speaking, the excreta 

 are returned to the soil, we shall find that there 

 is in practice a most sad deficiency. The dung- 

 heaps and cesspools, in which the night-soil and 

 urine are supposed to be stored up along with all 

 other domestic refuse, betray their trust. On the 

 one hand, the soluble matters, dissolved out by 

 atmospheric waters, to which they are, as a rule, 

 freely exposed, find their way into wells, ditches, 

 ponds, and thus gradually into the next stream. 

 We have often observed the completeness with 

 which this form of waste is carried on in many 

 villages in the eastern counties. On one side of 

 the road — or perhaps on both sides — is a ditch 

 which receives from every cottage, every farm- 

 yard, as well as from manured fields, a tiny drain, 

 rich in soluble organic matters. That these 

 ditches are on amicable terms of " give and take " 

 with the wells and pools which supply the village 

 with its supposed potable water, is a by-evil with 

 which we have at present no concern. On the 

 other hand, the cesspools and manure-heaps are 

 giving off their combined nitrogen to the atmos- 

 phere no less liberally than to the streams. Fer- 

 mentation is going on unchecked ; there is noth- 

 ing which may serve to arrest and condense the 

 volatile nitrogenous products, and when ultimate- 

 ly the contents of the heap or the pool are dug 

 into the garden or the allotment-field, instead of 

 containing, as they should, the entire fertilizing 

 ingredients excreted by the inmates of the cot- 

 tage, they consist chiefly of an impotent resid- 

 uum. To call this a restoration to the soil of 

 what has been taken from it is mere mockery. 

 Not one-half the compounds withdrawn from our 

 fields and gardens for the food of man, whether 

 in town or country, are ever returned to where 

 they belong. 



So far, however, we have dealt merely with 

 the waste of the fertilizing matter in human ex- 

 creta ; but there is also the case of our domestic 

 animals. When cattle and sheep are pasturing, 

 and when horses are working in the fields, not 

 only their dung, but their urine, is deposited upon 

 the soil. Under most other circumstances, how- 

 ever, the latter, which is the more valuable of the 

 two, goes to swell the waste we have already 

 mentioned. In the towns it is cbnveyed into the 

 sewers, and in the country it escapes into ditches, 

 adding thus no inconsiderable item to our yearly 

 loss of combined nitrogen. 



The remarks which we made on the waste of 

 nitrogenous matters by the processes of putre- 

 faction or fermentation going on in cesspools admit 



of a more extended application. Let us take the 

 case of ordinary town-sewage. We can calculate 

 with tolerable exactness how much nitrogen it 

 ought to contain per gallon, if we know the gross 

 number of the population and the total volume 

 of the sewage. The figure thus obtained will, 

 however, fall below the exact truth, since the 

 proportion of nitrogen entering the sewers will be 

 increased by the excretions of domestic animals 

 and by the washings of slaughter-houses, etc. 

 Yet if we take a gallon of the sewage, and sub- 

 mit it to actual analysis with the utmost care, we 

 shall obtain a result very much short of the cal- 

 culated percentage ; some twenty to fifty per cent, 

 of the combined nitrogen, more or less according 

 to circumstances, has escaped. In what form 

 this loss takes place can scarcely be doubted. 

 Were it given off as ammonia it could easily be 

 detected ; but ammonia does not readily evapo- 

 rate from such dilute solutions, and at such low 

 temperatures. We conclude, therefore, in accord 

 with two chemists who have made the analysis of 

 waters their specialty, and who on most points 

 differ very widely in opinion, that the loss takes 

 place in the form of free nitrogen. This we shall 

 find to be the case whenever vegetable or animal 

 matter containing nitrogen passes into a state of 

 fermentation. A part of such nitrogen reappears 

 as ammonia, and may be arrested by the aid of 

 absorbents and of certain acids and mineral salts ; 

 but a further portion is evolved as free nitrogen. 

 As far as we are aware, this loss becomes the 

 greater the larger the quantity of organic matter 

 which is allowed to collect. 



Here, then, in the very outset of our inquiries, 

 we have already met with a fearful waste of nitro- 

 gen committed in the normal course of daily life, 

 and without taking industrial operations into ac- 

 count. 



Let us next examine the manufacture of gun- 

 powder, and its allies, gun-cotton and nitro- 

 glycerine. The first of these substances contains 

 on an average 75 per cent, of saltpetre (nitrate 

 of potash), equivalent to 10.2 per cent, of com- 

 bined or available nitrogen. Of this 10.2 per 

 cent., 9.98 per cent. — we might consequently say, 

 practically speaking, the whole — escapes in the 

 form of free nitrogen, and is consequently ren- 

 dered useless. This waste will appear the more 

 serious if we consider the enormous scale upon 

 which gunpowder is now manufactured. It was 

 calculated some years ago that our annual exports 

 of this article alone amounted to 19,000,000 

 pounds' weight. We cannot estimate the total 

 quantity of gunpowder produced in the whole 



