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THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



by low organisms, animal or vegetable. These 

 will sooner or later become the food of fishes, 

 and the matter in question may thus ultimately 

 become available for human support. 



In one case, indeed we may, on the present 

 system, receive back sewage matters much sooner 

 than we wish. The particles of solids cast into 

 the sea " hug the shore," just as corks floating 

 in a basin of water keep to the side, and there 

 are swallowed by those " scavengers of ocean," 

 shrimps. Thus they may happen to be reeaten 

 by man even before assimilation. A chemist of 

 the present day, who occasionally writes on san- 

 itary topics from an original and independent 

 point of view, remarks tlmt thus — 



". . . . even-handed justice 

 Commends the poisoned chalice to our lips." 



A still more glaring example of waste occurs 

 in the case of nitrogen, an element having im- 

 portant analogies with phosphorus, rivaling the 

 latter in its relations to organic — and especially 

 to animal — life, and playing a far more important 

 and more varied part in the arts and manufact- 

 ures. Manifold in appearance as are the meth- 

 ods in which this king of the elements is wasted, 

 they may, with few exceptions, be reduced to one. 

 To understand this great mode of waste, we must 

 glance at the two almost contradictory aspects 

 which nitrogen is capable of assuming. On the 

 one hand, in its free gaseous state, as present in 

 the atmosphere it is the very type of indifference 

 and negation. We can merely say what it will 

 not do. But, on the other hand, when existing in 

 its solidified combined condition, and especially 

 in its organic compounds, it has more striking 

 positive attributes than perhaps any other of the 

 elements. No longer azote, as our French neigh- 

 bors persist in calling it, it might rather be 

 termed " zote " — if such a word may be framed 

 — the very essence of life. It is an indispen- 

 sable constituent of every vegetable seed and of 

 every animal ovum. Without it blood, muscle, 

 nervous tissue, are impossibilities. But in ad- 

 dition to its functions in the processes of life, 

 and therefore to its necessity in our diet, nitro- 

 gen — combined nitrogen, we must remember — 

 has other properties which render it useful, or 

 rather necessary, in numerous arts and manu- 

 factures. As a rule, we shall find that if any or- 

 ganic compound, whether existing naturally or 

 only produced by human intervention, possesses 

 very striking attributes, such compound is nitro- 

 genous. The most valuable fibres available for 

 our clothing, the richest dyes procurable for their 

 embellishment, the most precious medicines, the 



deadliest poisons, and last, though not least, 

 those explosives so largely prescribed by modern 

 humanitarianism in treating the diseases of bodies 

 politic — all these various bodies contain nitrogen 

 as an essential constituent. Such manifold utili- 

 zation, in the present imperfect state of our 

 knowledge, and in our still more imperfect dispo- 

 sition to make a rational application of what 

 knowledge we possess, leads to a waste equally 

 manifold. We say manifold in appearance, but 

 still resolvable into one common principle — the 

 conversion of solidified combined nitrogen into 

 the free, inert, gaseous nitrogen which exists in 

 the atmosphere. How vast are some of these 

 forms of waste we will endeavor to show in some 

 detail. 



Let us, first and foremost, look at the very 

 defective economy of nitrogen in the mainte- 

 nance of human life, under existing conditions. 

 In speaking of phosphorus we have already ad- 

 verted to the truth so perseveringly and authori- 

 tatively enforced by Liebig — that in growing 

 crops upon land we take away from the soil cer- 

 tain constituents, and that its crop-producing 

 power can only be prevented from diminishing 

 by a systematic return of such constituents in 

 the shape of the excretions of all living beings 

 fed on the produce of the soil. Our neglect in 

 fulfilling this condition is, perhaps, even more 

 conspicuous in the case of nitrogen than of phos- 

 phorus itself. On an average the daily excre- 

 tions of every human being contain half an ounce 

 of combined nitrogen. If we assume the popu- 

 lation of the British Islands at 32,000,000, this 

 amounts to a yearly quantity of 365,000,000 

 pounds. This weight of combined nitrogen, if 

 applied without loss to the soil and absorbed by 

 food-plants, would, if calculated in the form of 

 bread, be equivalent to 4,380,000,000 four-pound 

 loaves ! But how much of this fertilizing mat- 

 ter is really returned to the land ? The whole 

 of the sewage of London — in other words, the 

 whole of the excretions of its 4,000,000 inhabi- 

 tants — is substantially wasted by conveyance 

 into the sea. Here alone we have a national 

 loss of about 91,000,000 pounds of combined 

 nitrogen. The same disastrous game, differing 

 merely in unimportant matters, is played wher- 

 ever sewage is being allowed to flow either 

 directly into the sea or into a river or a canal, 

 without any attempt to separate and retain its 

 valuable constituents. Unfortunately, the mis- 

 chief is not confined to places where water-car- 

 riage has been adopted for the removal of ex- 

 crementitious matter. If we look at the case of 



