ously the
necessity of careful packing, and the enormous comparative power of
resisting smoke irritation possessed by our firemen, and the able
officer who commands them. Having heard from Captain Shaw that, in
some recent very trying experiments, he had obtained the best effects
from dry cotton-wool, and thinking that I could not have been mistaken
in my first results, which proved the dry so much inferior to the
moistened wool and its associated charcoal, I proposed to Captain Shaw
to bring the matter to a test at his workshops in the City. He was
good enough to accept my proposal, and thither I went on May 7, 1874.
The smoke was generated in a confined space from wet straw, and it was
certainly very diabolical.

At this season of the year I am usually somewhat shorn of vigour, and
therefore not in the best condition for severe experiments; still I
wished to test the matter in my own person. With a respirator which
had been in use some days previously, and which was not carefully
packed, I followed a fireman into the smoke, he being provided with a
dry-wool respirator. I was compelled to quit the place in about three
minutes, while the fireman remained there for six or seven minutes.

I then tried his respirator upon myself, and found that with it I
could not remain more than a minute in the smoke; in fact the first
inhalation provoked coughing.

Thinking that Captain Shaw himself might have lungs more like mine
than those of his fireman, I proposed that we should try the
respirators together; but he informed me that his lungs were very
strong. He was, however, good enough to accede to my request. Before
entering the den a second time I repacked my respirator, with due
care, and entered the smoke in company with Captain Shaw. I could
hear him breathe long slow inhalations; his labour was certainly
greater than mine, and after the lapse of seven minutes I heard him
cough. In seven and a half minutes he had to quit the place, thus
proving that his lungs were able to endure the irritation seven times
as long as mine could bear it. I continued in the smoke, with hardly
any discomfort, for sixteen minutes, and certainly could have remained
in it much longer. The advantage arising from the glycerine was thus
placed beyond question.

During this time I was in a condition to render very material
assistance to a person in danger of suffocation.

Helmholtz on Hay Fever.

In my lecture on Dust and Disease in 187