Encyclopaedia Britannica, or, a Dictionary of arts, sciences, and miscellaneous literature : enlarged and improved. Illustrated with nearly six hundred engravings > Volume 6, CHI-Crystallization

CON [596
Contagion, 1773. Purfutng this hint, no doubt, Dr Carmichael
v Smyth propofed the fumes of nitric acid. This was
tried on board different ffiips at Sheemeis about the
year 1796 5 and being found to anfwer the purpofe
of deftroying the contagion which then prevailed, Dr
Smyth afterwards received a liberal reward from go¬
vernment for his difcovery. Thefe experiments were
conducted on board the Union hofpital (hip by Mr
Menzies furgeon of the Difcovery, and Mr Baffan fur-
/ geon of the Union. The wards at this time were
very much crowded with patients 5 and of 200 fick
on board, 150 were in different ffages of a malignant
contagious ferer, which made a very rapid pragrefe,
and produced very fatal dte&s on the attendants and
ihip’s company.
The materials and apparatus employed in the procefs
were the following: A quantity of fine fand, two dozen
quart earthen pipkins, as many common tea-cups, fome
long flips of glafs to be ufed as fpatulas, a quantity of
concentrated fulphuric acid, and a quantity of faltpetre
(nitrate cf potalh).
The procefs was conducted in the following manner ;
iff, All the ports and fcuttles were (hut up 5 the fand,
previoufiy heated in iron pots, was fcooped out into
the pipkins with an iron laddie 5 and in this heated fand,
in each pipkin, a fmall tea-cup was immerfed, contain¬
ing about half an ounce of fulphuric acid, to which,
after it had acquired a proper degree of heat, an equal
quantity of nitrate cf potaffi in powder was gradually
added, and the mixture ftirred with a glafs fpatula till
the vapour arofe from it in confiderable quantity. The
pipkins were then carried through the wards by the
mvrfes and convalescents, who kept walking about with
them in their hands, occafionally putting them under
the cradles of the fick, and in every corner where any
foul air was fufpeCled to lodge. In this manner they
continued fumigating, until the whole fpace between
decks, fore and aft, w'as filled with the vapour, which
appeared like a thick haze.
The vapour at firft excited coughing atnong the pa¬
tients, which gradually .ceafed as it became more ge¬
nerally diffufed through the wards : part of this effeft,
however, was to be attributed to the inattention cf
thofe who carried the pipkins, in putting them too near
the faces of the fick 5 which caufed them to inhale
the ftrong vapour as it immediately iffued from the
cups.
The body-clothes and bed clothes of the fick were,
as much as poffible, expofed to the nitrous vapour du¬
ring the fumigation ; and all the foul linen removed
from them was immediately immerfed in a tub of cold
water, afterwards carried on deck, rinfed out, and hung
up till nearly dry, and then fumigated before it was
taken to the wafh-houfe : a precaution extremely necef-
lary in every cafe of infeflious diforder. Proper at¬
tention was alfo paid to cieanlinefs and ventilation.
Three hours were at firft found neceflary to fu¬
migate the (hip. In about an hour after, the va¬
pour having entiiely fubfided, the ports and fcuttles
were thrown open for the admifflon of frelh air. It
could plainly be perceived that the air of the hofpital
was greatly fweetened even after this firft fumigation.
The procels was repeated again next morning 5 and
the people employed, being now more expert, finifhed
ike whole in about an hour’s time. In an hour after-
6
] CON
wards, the vapour having entirely fubfided, the freih
air was freely admitted into the hofpital as before.
Fewer pipkins were employed for the evening fumiga¬
tions than for thoie of the mornings, as the freih air
could not be admitted fo freely after the former as the
latter.
The pleafing and immediate effedl of the fumigation
in deftroying the offenfive and difagreeable fmell, arifing
from fo many fick crowded together, was now very
perceptible, even to the attendants 5 the confequence
of which was, that they began to place fome degree
of confidence in its efficacy, and approached the cradles
of the infefted with lefs dread of being attacked with
the diforder : thus the fick were better attended, and
the duty of the hofpital was more regularly and more
cheerfully performed.
From the 26th of November 1795, when the fumi¬
gation was firft reforted to, till the 25th of December,
not a perfon on board was attacked with the fever,
though, in the three months preceding, more than one-
third of all the people in the ffiip had been feized with
the diftemper, and of thefe more than one in four
were carried off by it 5 and the probability is, that the
ficknefs and mortality would have gone on, increafing
in proportion to the diffufion of the contagion, and
to the increafing defpondency of the people, who con-
fidered themielves as fo many devoted vifffim?.
The advantage of the fumigation was not felt by the
fill p’s company and attendants alone, whom it pieferved
from the baneful effe&s of the fever : the fick and con-
valefcents derived almoft an equal benefit from it. The
fymptoms of the difeafe became milder, and loft much
of their malignant appearance 5 and the advantage of a
pure and fweet air to convaleicents rauft be obvious.
Great confidence is always dangerous. It proved fo
on the prefent occafion. On the 17th of December
they imagined themfelves fo fecurc, that they difeon-
tinued the cuftom of fumigating morning and evening,
thinking that once a-day was fufficient. On the 25th,
one of the nurfes fuffered a flight attack 5 and on the
26th a marine, who, for a week before, had been in a
ftate of intoxicatisn, was feized with the fever, and
died. Thefe two accidents gave immediate alarm:
they returned again to the practice of fumigating twice
a-day ; and from that time to the extermination of the
diforder, there was not an inilance of a perfon fuffering
from contagion on board the ffiip.
The fuccefs of the experiment was not confined to
the Union : the power of the nitrous vapour to deftroy
contagion was equally difplayed on board fome Ruf¬
fian (hips then in the Downs. The fafety, too, with
which it may be employed, in any fituation, without
inconvenience or riik of fire, is another great recom¬
mendation in its favour.
It wdll not be difficult from this defeription to em¬
ploy this kind of fumigation. It is only neceffary to
obferve, for the fake of thofe who may not be verfant
in chemical purfuits, that the ingredients ought to be
pure, and neither metal veffels nor rods (hould be ufed.
Any kind of metal getting among the ingredients
wtould caufe the vapour to be very noxious inftead of
falutary. The fumes that rife (hould be white } if
they are of a red colour, there is reafon to fufpedl the
purity of the ingredients.
The importance cf this difeevery need not be iufiffed
Contai
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