100 
ON CHLOROFORM. 
The qnanlity of this vapour in the air the patient inhaled, 
at ordinary temperatures, was only about a quarter as 
much by measure as there would be of ether — being, how- 
ever, nearly twice as heavy ; there was nearly half as much 
by weight. Now, on account of the small space it occu- 
pied, it only excluded the air to a quarter the amount that 
ether-vapour did, and therefore interfered but little with 
the natural process of respiration ; the patient, indeed, could 
take in nearly the usual amount of oxygen without quick- 
ening or enlarging the respiratory movements. It was to 
be observed that temperature exerted a great influence 
over the quantity of this vapour that air would take up, 
and thus an elevation of little more than fifteen degrees in 
the warmth of the apartment, would double the amount of 
it which the patient would inhale in a given time, if no 
means were taken to regulate the evaporation. Dr. Simp- 
son recommended the chloroform to be inhaled from a 
sponge or handkerchief, and this simple means was effi- 
cient ; but he (Dr. Snow) preferred to use an apparatus, as, 
without it, more of the vapour was blown away by the 
warm breath of the patient, than was inhaled. The strength 
of the vapour could not be regulated ; it could not even 
be known when it was all expended, and no exact obser- 
vations could be collected. The chloroform was of easier 
application than ether, on account of its quicker action; 
but, for the same reason, greater care was required in its 
use, to avoid accident.'^ 
In conclusion, it may be well to repeat, what has already 
been stated, that chloroform differs from the liquids sold 
under the names of ch loric el/ic.raud ierchloride of carbon^ 
inasmuch as these last-named substances are solutions of 
chloroform in spirits of wine, and the processes originally 
given for the preparation of these would be inapplicable 
for the preparation of chloroform. 
Chloric ether and ierchloride of carbon are subject to 
much greater variations in quality and composition than 
chloroform is. There are no recognized standards by 
