little danger from the cold in this situation, and the air having freer
access to the skin might produce a greater effect. Being no physician, I
run no risk by throwing out these random, and perhaps whimsical
proposals.[5]

Having communicated my observations on fixed air, and especially my
scheme of applying it by way of _clyster_ in putrid disorders, to Mr.
Hey, an ingenious surgeon in Leeds a case presently occurred, in which
he had an opportunity of giving it a trial; and mentioning it to Dr.
Hird and Dr. Crowther, two physicians who attended the patient, they
approved the scheme, and it was put in execution; both by applying the
fixed air by way of clyster, and at the same time making the patient
drink plentifully of liquors strongly impregnated with it. The event
was such, that I requested Mr. Hey to draw up a particular account of
the case, describing the whole of the treatment, that the public might
be satisfied that this new application of fixed air is perfectly safe,
and also, have an opportunity of judging how far it had the effect which
I expected from it; and as the application is new, and not unpromising,
I shall subjoin his letter to me on the subject, by way of _Appendix_ to
these papers.

When I began my inquires into the properties of different kinds of air,
I engaged my friend Dr. Percival to attend to the _medicinal uses_ of
them, being sensible that his knowledge of philosophy as well as of
medicine would give him a singular advantage for this purpose. The
result of his observations I shall also insert in the Appendix.

FOOTNOTES:

[5] Some time after these papers were first printed, I was pleased to
find the same proposal in _Dr. Alexander's Experimental Essays_.

SECTION V.

_Of AIR in which a mixture of BRIMSTONE and FILINGS of IRON has stood._

Reading in Dr. Hales's account of his experiments, that there was a
great diminution of the quantity of air in which _a mixture of powdered
brimstone and filings of iron, made into a paste with water_, had stood,
I repeated the experiment, and found the diminution greater than I had
expected. This diminution of air is made as effectually, and as
expeditiously, in quicksilver as in water; and it may be measured with
the greatest accuracy, because there is neither any previous expansion
or increase of the quantity of air, and because it is some time before
this process begins to have any sensible effect. This diminution of air
is various; b