5 2 
Economy of Nitrogen. 
[April, 
excretions of every human being contain half an ounce of 
combined nitrogen. If we assume the population of the 
British islands at 32 millions, this amounts to a yearly 
quantity of 365 million lbs. This weight of combined ni- 
trogen, if applied without loss to the soil and absorbed by 
food-plants, would, if calculated in the form of bread, be 
equivalent to 4380 million 4-lb. loaves ! But how much of 
this fertilising matter is really returned to the land ? The 
whole of the sewage of London — in other words, the whole 
of the excretions of its four million inhabitants — is substan- 
tially wasted by conveyance into the sea. Here alone we 
have a national loss of about 91 million lbs. of combined 
nitrogen. The same disastrous game, differing merely 
in unimportant matters, is played wherever sewage is 
being allowed to flow either diredtly 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-carriage 
has been adopted for the removal of excrementitious 
matter. If we look at the case of 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 
farmyard, 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 atmosphere no less 
liberally than to the streams. Fermentation is going on 
unchecked ; there is nothing which may serve to arrest and 
condense the volatile nitrogenous products, and when ulti- 
mately the contents of the heap or the pool are dug into 
the garden or the allotment-field, instead of containing, as 
