290 
AMERICAN AGRICULTURIST. 
[OCTOBETC, 
causes a painful swelling and even troublesome 
ulcers. This is intended to give an idea of the 
structure and habits of mosquitoes in general, 
and not of any particular species. Our mos- 
quitoes belong to the genera Megarhinus,im& Culex, 
but they do not seem to have been thoroughly 
studied, and there is much confusion among 
naturalists concerning them. It is somewhat 
consoling to know that but a small proportion 
of the wigglers ever reach the perfect state. 
Myriads are lost in the process of liberating 
themselves from the pupa case. The stillness of 
the air, or otherwise, at this particular season 
in the life of the musquito, explains why the 
insects are so much more abundant in some 
Fig. 7. — STINGS AND SUCKERS OP MOSQUITOES. 
years than in others. Great numbers are de- 
voured by Dragon-flies, which at the South 
are called " mosquito hawks." "We have seen 
mosquitoes so plenty near New Orleans, as to 
darken the wall of a building upon which 
they were resting during the day time, while 
great numbers of these mosquito hawks were 
flitting about and devouring them by thousands. 
About Charcoal as a Deodorizer and an 
Ingredient of Manure. 
e 
The errors of reading and thinking men 
sometimes indicate subjects which it is profit- 
able to discuss for the better information of the 
public. The subscriber sending the following 
will therefore, we hope, excuse the use made of it. 
"Wherever the refuse of coal pits or bins can 
be bought, few things are more useful to the 
gardener. Charcoal acts as an absorbent of the 
gases from decaying animal and 
vegetable matter, and the product 
when applied to growing crops be- 
come a powerful fertilizer. From 
the fact that charcoal dust rubbed 
over tainted flesh and allowed to 
remain on it a few hours will re- 
move all unpleasant smell and taste, 
it has sometimes been inferred that 
it acts as a preservative from decay. 
This is a mistake. It takes up the 
noxious gases, and holds them in 
its cells, but does not arrest de- 
composition. The bodies of two 
dead dogs were placed in a wooden 
box, and covered several inches 
thick with powdered charcoal, and 
the box left open. No effluvia was 
ever perceptible ; yet at the end of 
six months little remained but the 
bones. This shows that charcoal 
absorbed the gases of decay, but did 
not stop it. These odors, offensive 
and hurtful to mankind, it stores 
away and holds until wanted for 
use in promoting vegetable growth. 
Obviously, then, we should use charcoal dust 
about our privies, sinks, drains, stables, or 
wherever there is any decomposition going on." 
Wrong ! The facts are true, the main ones, — 
the deductions, obvious perhaps, but false. 
Charcoal is one of the most porous substances. 
The wood from which it was made consisted of 
oxygen, hydrogen and carbon; the burning 
drove off the oxygen and hydrogen, and left the 
carbon. The plant cells of which the wood was 
formed are by the burning all opened, and each 
minute cell has an outside and inside surface, 
the form of which is perfectly retained in the 
coal. This shows that an almost inconceivable 
extent of surface is exposed. Much as if in a 
bushel of turnip seed the insides were all out, 
leaviug nothing but the shell-like skins. The 
minute plant cells making up the wood, con- 
sisted of innumerable particles, each containiug 
12 atoms of carbon, 10 of hydrogen and 10 
of oxygen. 'And although these compound 
atoms of cell-substance are so small that the 
most powerful microscopes can not show them, 
yet we know that each consists of the atoms, 
and in the proportions named. When, there- 
fore, all but the carbon is driven off by heat, 
most of the carbon, which the heat can not fuse, 
remains filling the space which it originally oc- 
cupied in connection with the other elements, as 
an exceedingly porous mass, infinitely increas- 
ing the^surface exposed to the action of gases. 
Charcoal has, in common with many other 
substances in a state of very minute subdivision, 
the property of condensing upon its surface va- 
rious gases, some more than others. Thus, when 
a piece of charcoal freshly heated -is placed in 
a jar of oxygen gas, it will absorb many times 
its own bulk, the gas not filling the coal as wa- 
ter fills a sponge, but being condensed upon the 
surface, as the moisture in a room is condensed 
on the window panes in winter. The most 
wonderful fact about this condensation of gases 
in such materials is, that after all the oxygen or 
other gas, possible, has been taken up, the coal 
or porous body is capable of absorbing still 
other gases to a great extent. Fresh charcoal 
will absorb 80 to 100 times its own bulk of am- 
monia, but it will part with all, or nearly all, in 
presence of water, or moist air. 
When different gases capable of combining 
mingle in the air, if they combine at all, they 
often do so very slowly, but when they come to- 
gether condensed in the pores of the charcoal, 
chemical union very easily takes place. So it 
is, that when the products of the decomposition 
of animal substances, etc., being in the gaseous 
form, are absorbed by charcoal, the oxygen of 
the air being* absorbed at the same time, the 
oxygen at once combines with them and bums 
them up, just as if they burned in a flame. 
In the case mentioned by our correspondent, 
the air and warmth caused the dogs to de- 
compose ; the charcoal absorbed the gases and 
caused them to unite with oxygen, so that car- 
bonic-acid gas, water, and ammonia were the 
principal results. These, for the most part, 
were not retained by the coal, (though some 
of the ammonia was,) but they escaped into the 
air. Under such circumstances the smell of am- 
monia may be perceived, but is not very observ- 
able. When charcoal dust is mixed with decom- 
posing substances, the facts that concern us, are, 
1st, that it prevents bad smells ; 2d, that it ab- 
sorbs a portion of ammonia, (i. e. carbonate 
of ammonia) ; 3d, that it thus becomes of ferti- 
lizing value; 4th, that when employed in moder- 
ate quantities, it will soon take up all the am- 
monia it is capable of retaining and the rest will 
escape, and thus considerable losses may occur; 
5th, that the quantity of ammonia taken up and 
retained is very variable, and maybe very little; 
6th, the presence of charcoal causes a much 
more rapid decomposition than would other- 
wise occur, for it brings a large supply of oxy- 
gen, which it condenses from the air, almost in 
immediate contact with the decomposing mat- 
ter. This is the secret of its purifying tainted 
meat, for the action of this oxygen, influenced 
perhaps by the presence of the charcoal, is to 
cause the thorough consumption or burning up 
(the oxidization) of all those particles of the out- 
side of the meat which have become tainted. 
It is clear then, that charcoal dust ought not 
to be mixed with manure, in the hog-pen, in 
the privy, or anywhere ; that animal matter 
ought not to be composted with charcoal, even if 
a very large quantity be used. If the substance 
be mixed first with charcoal, and then covered 
with soil or muck, little loss will take place 
and the coal will be a real benefit. — Mechani- 
cally and chemically charcoal is often of great 
benefit to the soil. As a stomachic and cor- 
rective it is excellent to mix with the food of 
animals, hogs especially, if needed medicinally. 
Ice-Houses— Drainage and Ventilation. 
— • — 
Many inquiries are proposed to the Agricul- 
turist in regard to ice-houses. Where to put 
them? How to drain them?* How and why to 
ventilate them, etc. Oue subscriber " can't make 
his ice keep after July or August." Another 
building his house altogether above ground, 
allows a circulation of air among the rails on 
which the ice is laid, and wonders why it does 
not keep better. Now, ice-houses are quite as 
good entirely above ground as below, and on 
some accounts we think better. Good walls of 
wood filled in with sawdust are much better ■ 
non-conductors of heat than stones, even though 
a board lining, packed well with sawdust be- 
tween it and the stone wall, be provided. The 
