146 
Economy of Nitrogen . 
[April, 
in sea-water, the gold in many varieties of quartz and 
pyrites, and the sulphur in coal. To obtain a shilling’s 
worth of silver from sea-water costs more than a shilling, 
and the amount of precious metal thus dissolved in the 
ocean — immense as it doubtless is — may be, in our present 
state of knowledge, pronounced practically non-existent. 
Now Art is constantly engaged in reducing useful sub- 
stances into a similar condition. Every time a sovereign is 
handled in the course of business, or shaken against other 
coins in the purse or the cash-box, some small trace of gold 
is abraded. The quantity lost may be too trifling to be 
visible, and might even elude spectroscopic detection ; but 
that loss does constantly take place we know, since by the 
mere continuance of such ordinary wear and tear the current 
coin of the realm ultimately becomes “ light.” The silver 
fork or spoon, the brass-work of the microscope and the 
balance, the leaden gutter or spout, the iron key, spade, or 
wheel-tire, are all in like manner gradually wearing away, 
losing their substance in particles so minute as to elude 
observation, and becoming thus distributed no one can say 
where. Nothing is indeed destroyed, but everything is 
becoming mixed. There may be natural processes by which 
all these microscopic films and fragments of metals, and 
other useful substances, are being sorted out and collected 
together, like to like, and are being formed into veins and 
beds of ore, &c., for future generations to extract and again 
bring into use ; but such processes, if they exist at all, are 
assuredly very slow. We scatter more rapidly than Nature 
gathers. We are living beyond our income, and, except as 
far as some few of the commoner elements are concerned, 
we must ultimately, in the words of the old adage, “ find 
the bottom of the bag.” 
Another form of waste consists in taking an elementary 
substance, useful in its free state or in some particular com- 
bination, and transmuting it into compounds no longer 
capable of the same applications. Of this class of waste 
the consumption of coal may serve as the type. Carbon 
and certain compounds of carbon and hydrogen combine 
with oxygen, the main resulting product being carbonic 
acid, accompanied, in the case of the hydrocarbons, with 
watery vapour. Now carbonic acid is certainly not useless 
in the economy of Nature, being one of the most important 
ingredients in the food of plants, but in our hands it is what 
the old alchemists called a caput mortuum — a residue which, 
economically speaking, must be pronounced intractable. 
There is no need to insist here upon the vast supply of this 
