20 
POPULAR SCIENCE REVIEW. 
the resulting compound, the size of a nut, is to be applied over 
the part that is to be operated on. The arsenic so sublimed is 
described, adds Snow, “ as rendering surgical operations ex- 
tremely pleasant ; ” but with his keen scepticism he analyses, 
distrusts, and practically does away with the whole story. 
The benumbing influence of extreme cold may be accepted 
as a natural discovery, coeval with the existence of mankind in 
the temperate and frigid zones, and physicians, at an early date, 
seemed to have used cold for the relief of pain. Its systematic 
use probably came in later; after the revival of letters, so 
called. It is related of Harvey, the discoverer of the circulation 
of the blood, that he was accustomed to seek relief from the pain 
of gout by going on the leads of his house, and there immersing 
his painful foot in ice-cold water. But we have to name 
another man, living in the same age, to see the same remedy em- 
ployed in a direct manner in order to remove sensation in a part 
of the living body before subjecting the part to operation. This 
man was Thomas Bartholinus, one of the most learned and in- 
dustrious masters in physic. Bartholinus wrote a treatise of 232 
pages on the medical uses of snow (“ De Nivis Usu Medico ”). 
The book, from beginning to end, is wonderfully suggestive, and 
in the twenty-second chapter he conveys the practice of apply- 
ing extreme cold to produce insensibility before the performance 
of surgical operations. The plan, he says, was taught to him 
by Marcus Aurelius Severinus of Naples. In our day the same 
application of cold has been, independently, brought into use 
by a man of singular originality and genius, Dr. James Arnott. 
One more method calls for a word, and that is the method of 
removing sensibility to pain by means of pressure. This plan 
is fully described by Bell, in a chapter entitled, “ Preventing or 
Diminishing Pain during Chirurgical Operations.” He says it 
has long been known that the sensibility of any part may not 
only be lessened, but even altogether suspended, by compres- 
sing the nerves which supply the part. To effect this sys- 
tematically, Mr. James Moore, of London, invented, in 1784, 
an instrument which produced pressure on the large nerves, 
an instrument which was tested by no less a surgeon than 
John Hunter, in St. George’s Hospital. It partially succeeded, 
but the pressure had to be maintained an hour before the 
operation, and the proceeding fell into disuse. 
We are brought now to the early part of the present century, 
and to the researches of Sir Humphrey Davy. Sir Humphrey 
discovered that nitrous oxide gas, when inhaled, produces in- 
sensibility to pain, a kind of intoxication, and sleep. In the 
course of his enquiries he tells us that he had a very good oppor- 
tunity of ascertaining the power of the immediate operation of 
the gas in removing intense physical pain. In cutting one of 
