390 . CARBOLIC ACID AS A DISINFECTANT, ETC. 
science, all testified to the great pecuniary value of the sewage 
of the country. One valued it at £15,000,000, another at 
£52,000,000, a third at £64,000,000, and Dr. Parkins, 
guided by the calculations of Professor Playfair, estimated 
its value at £93,283,000 a year. The figures might appear 
fabulous, still they serve to shew that it is time something 
should be done, and that not only in an economical point of 
view, but to prevent the engendering of disease both in man 
and animals by the emanations from decomposing excreta. 
Moreover, it is feared by some persons that the supply of 
guano will ere long fail. Respecting this Baron Liebig 
says : 
In relation to guano I have been assured that in twenty to 
twenty-five years, if the use of guano should increase in even 
the same proportion as hitherto, there will not remain in South 
America enough to freight a ship. We will, however, sup¬ 
pose its supply and that of bones to continue for 50 years, 
or even longer; then what will be the condition of England 
when the supply of guano and bones is exhausted? 
“ This is one of the easiest of all questions to answer. If 
the common sewerage system is retained, then the im¬ 
ported manures, guano and bones, make their way into the 
sewers of the cities, which like a bottomless pit, have for 
centuries swallowed up the guano elements of the English 
fields, and after a series of years, the land will find itself 
precisely in the condition it was before the importation of 
guano and bones commenced; and after England shall have 
robbed the cultivated lands of Europe, even to complete ex¬ 
haustion, and taken from them the power to furnish her 
longer with corn and manure, then she will not be richer 
than before in the means of producing corn and meat, but 
will from that time forth become even poorer in these means. 
{i It has been maintained that the recovering of the manure 
elements out of the sewers of large cities is impractible. I 
am not ignorant of the difficulties which stand in its way. 
They are, indeed, very great; but if the engineers would 
come to an understanding with the men of science in relation 
to the two purposes — the removal of the contents of the 
sewers, and the recovery of their valuable elements for agri¬ 
culture—I do not doubt that a good result would follow. 
Intelligence, in union with capital, represents a power in 
England wffiich has rendered possible and practicable things 
of much greater apparent difficulty.^ 
Since the above was written, we have met with the follow¬ 
ing letter in the public prints, which we insert; for we concur 
with the opinion expressed by Lord Palmerston at a late 
