$12 
poses; for although the enterprizing 
spirit of speculation may induce them 
to erect buildings in the neighbourhood, 
and. consequently to construct) sewers 
and partial drains to carry off the sur- 
face water, yet it may be assumed as a 
matter quite impossible to render the air 
of such a district even moderately sa- 
lubrious.  . 
Though the exhalations arising from 
the putrefaction of vegetable matter 
would in ‘some degree be diminished by 
covering one-third or one-fourth of the 
surface with buildings; yet atmospheric 
air, saturated with moisture and con- 
fined, even for a short period, within 
the walls of a building, is well known 
to be unfit for respiration, more es- 
pecially by those persons who have not 
the advantage of robust health, or who 
are devoted to sedentary employments. 
Mr. Faraday having, in the last nunr- 
ber of the Journal of Science, given an 
account of the method pursued under 
his direction for fumigating this prison, 
I shall conclude my present remarks by 
quoting a few of his observations. 
After deciding upon fumigating the pri- 
son (says Mz. Faraday) by chlorine (gas), 
the next mode was to ascertain the most 
favourable mode of applying it; and I was 
desirous, for many reasons, of obtaining a 
gradual and successive development of the 
disinfecting agent, rather than a sudden and 
short one. -The latter mode, though it 
would have filled the building at once, and 
probably very effectually, yet would se- 
‘riously have incommoded the operators, and 
would also soon have disappeared in con- 
sequence of absorption by the limed walls, 
and from dissipation through apertures that 
would inevitably remain unclosed in dif- 
ferent parts of the building; whilst the for- 
mer mode, by continually supplying the 
disinfecting agent to the atmosphere of the 
place for a length of time, would enable it 
better to act on the bedding, clothing, and 
other articles left in the cells, and allow it 
also to penetrate more perfectly to every 
part of the building itself. 
The materials used were those usually 
employed for the purpose, namely, com- 
mon salt, oxide of manganese in powder, 
and oil of vitriol. On making experiments 
with these substances as furnished by the 
dealer for the fumigation, [ found that mix- 
ture of one part by weight of common salt, 
“and one part of manganese, when acted 
upon by two parts of oil of vitriol pre- 
* viously diluted with half its weight of water, 
and left until cold, gave the best results. 
Such a mixture made at the temperature 
60° Fahrenheit, liberated no muriatic acid, 
but in a few minutes began to evolve chlo- 
“rine vapour, and continued to do so for the 
space of four days subsequent. “When exa- 
Milbank Penitentiary. 
[ Nov. 1, 
mined on the fifth day, and urged by heat 
so as to make the liquid evolve all the 
chlorine it contained, very little additional 
was procured. . Such a mixture may, there- 
fore, be. considered as. having liberated its 
chlorine gradually, but perfectly without the 
application of any extraneous heat, and is 
therefore very proper for extensive. fumi- 
gation, 
The vessels in which the mixture is to 
be made should be flat, and such as are 
least liable to be acted on by the chlorine 
or the acid mixture. Common red pans 
were used in the Penitentiary, for, a con- 
siderable number being. required, ‘better 
earthenware would haye been. too expen- 
sive. Each pan. contained. about. four 
quarts. rar 
The salt being pulverized by a wooden 
mallet, an equal quantity of the oxide of 
manganese was added and well mixed to- 
gether. The acid and water were mixed 
im a separate wooden tub; the water being 
poured in first, and the acid added, gradu- 
all stirring it at the time, the heat produced 
being considerable, it will be necessary to 
allow a few hours for it to subside previous 
to adding the whole of the acid, when it is 
to be well stirred and left to cool. _ The di- 
luted acid was mixed with the salt and 
manganese, in the proportion «f 44 pounds 
of the former to 33 pounds of the latter, and 
the mixture well stirred. This was done 
without any inconvenience to the operator, 
except when the acid was applied too warm : 
there was sufficient time to go from pan to 
pan, and to close the various galleries in 
succession. In half an hour it was almost 
impossible. to enter, and in. Jooking along 
the gallery (150 feet in length), the.yellow 
tint of the atmosphere could be easily per- 
ceived ; and up to the fifth day the, pecu- 
liar odour of the chlorine gas could be dis- 
tinguished throughout the building. After 
the sixth day the pans were removed 
(though in some cases with difficulty), to 
be emptied and used elsewhere; after 
which the doors and windows. of the’célls, 
which had been carefully steppedy:pre-_ 
viously, were thrown open. It was esti- 
mated that the contents of each pan would 
yield about 54 cubic feet, or one,pound 
weight of chlorine gas. The whole quan- 
tity of materials used was 700 Ib, of salt, 
700 lb of manganese, and 1,400 Ib. of oil of 
vitriol The space requiring fumigation 
amounting to nearly 2,000,000 cubic feet ; 
and the surface of the walls, inclusive of the 
furniture, &c., about 1,200,000 square feet. 
This surface was principally stone and brick, 
most of whieh had been lime washed. The 
number of cells and other apartments: was 
nearly 1,200. 
It. was desirable for many reasons that 
the Penitentiary should be fumigated in the 
most unexceptionable. manner; ,and the . 
means employed were therefore probably to 
a far greater extent than might have been 
necessary for the destruction of any mias- 
mata 
