22 
POPULAR SCIENCE REVIEW. 
bably be used with advantage during surgical operations in 
which no great effusion of blood takes place.” This idea had 
been formed after ten months of continuous and often 
hazardous experiments. It was on the 16th of April, 1799, 
that Davy inhaled nitrous oxide for the first time ; he states 
that the introduction of this gas into the lungs was accom- 
panied by a loss of sensation and voluntary motion, but does 
not recollect what followed. 
Nitrous oxide is one of the most remarkable gases with 
which we are acquainted. It is a transparent, colourless gas, 
like ah-, easily prepared by heating nitrate of ammonia ; it has 
a sweetish taste and a faint odour. It has sometimes been 
called “ laughing-gas,” on account of its singular propertj 7 of 
inducing involuntary laughter in some who inhale it. This gas 
cannot be breathed for more than a short time, because its 
peculiar action on the nervous system soon paralyzes the volun- 
tary muscles of the mouth, which, accordingly, cease to grasp 
the tube of the apparatus, and common air enters the lungs. 
An animal confined in nitrous oxide gas soon dies after ex- 
hibiting symptoms of excitement. When inhaled by man, it 
first produces a sensation of warmth in the chest, which 
warmth soon spreads to the extremities, then follows paralysis 
of the muscles of the mouth, which puts a stop to the further 
breathing of it. After a short period of quiet or stupor, the 
patient becomes excited — laughs, sings, dances, &c. In the 
course of a minute or two, all these effects pass off suddenly, and 
he returns to full consciousness with a bewildered stare, having 
no recollection, or a very confused one, of what has passed. It 
is, in fact, a true case of somnambulism, momentarily produced. 
But, in some instances, this period of excitement does not 
manifest itself, or is only of very short duration, and then comes 
on a kind of stupor and a complete state of anaesthesia. But it 
is only with patients who are very sensitive to the action of the 
gas that this state of insensibility to pain can be produced. The 
late Dr. Gregory, of Edinburgh University, made several expe- 
riments with nitrous oxide, by which he has shown that its 
action upon the economy is precisely similar to that of ether or 
chloroform, though it cannot be taken by most patients in 
sufficient quantity (owing to the paralysis of the muscles of the 
mouth) to procure complete anaesthesia. 
Forty years after Davy’s experiments, in 1844, Horace Wells, 
a surgeon-dentist of Connecticut (North America), applied 
nitrous oxide to tooth-drawing. The first operation was made 
upon himself ; and, when his senses returned, he exclaimed : 
“ This is, indeed, a new era in tooth-drawing ! ” He afterwards 
practised this mode of producing anaesthesia for some time, 
with considerable success. But, unfortunately, in some expe- 
