18 
been obtained by blowing some finely divided plaster of 
Paris against small splinters of wood by means of a jet of 
steam. 
In the discussion which followed my paper, Dr. Crompton 
suggested 
The Ether Spray, 
such as is used in surgery as a means of obtaining a 
frozen fog. And shortly after the meeting I tried this 
ether spray, using an instrument such as surgeons use. 
But although I found that the spray would freeze anything 
such as a small tube of water, I could get no deposit of ice 
particles on the outside of any object. I varied the form of 
the apparatus, but with no better success, and for the time 
I abandoned the attempt. 
What the cause of this failure was I do not precisely 
know, but I attribute it to some excess of alcohol in the 
ether then used, which was not methylated ether. That 
this might have been the cause occurred to me about two 
months ago. I then determined to try again, and combine 
a spray of water with that of ether. I now obtained the 
lightest ether which Messrs. Mottershead & Co. could supply. 
The specific gravity of this was '717, and it was made from 
methylated spirit. 
With this, somewhat to my surprise, I at once obtained 
a deposit of ice even without the water spray, and with 
the same apparatus I had previously used. It was not, how- 
ever, until I used the combined spray of water and ether 
that I obtained anything resembling a hailstone in appear- 
ance. But the first time I used this combination 1 obtained 
a small but well-shaped hailstone on the end of a match, 
which I held pointed towards the spray. 
The next time I tried, however, on another day, I did 
not succeed so well with the water as without it. 
When using the water spray the deposit of ice was wet 
or half melted, while without the water I obtained a hail- 
