408 
the water. This substance has the 
- appearance of an exceeding fine, 
light, and very moveable yellow 
powder, and it is very inflammable; 
so much so, that being blown out 
of a quill into the flame of a candle, 
it flashes like gunpowder ; and it is 
made use of in this manner in our 
theaires for imitating lightning. 
Conceiving that there must have 
been a strong attraction between this 
subsiance and air, and suspecting, 
from some circumstances attending 
some of the foregoing experiments, 
The Bulb of the Thermometer surrounded by 256 grains of Semen Lycopodii. 
Cooled. 
Heat lost. a Heat 
———— | acquired, ; [—————-—_.—— 
Exp. No. 28. Exp. No. 29. Exp. No. 30. 
70° ae ose o* 
60 146" 157" 10 
50 162 160 123 68 
40 175 170 30 63 
30 209 203 40 76 
20 284. 288 50 121 
10 502 AoLS 0 316 
—_ em =m 70 1585 
Total times 1478 1491 _ 2459 
In the last experiment (No. 30) 
the result of which was so very 
extraordinary, tbe instrument was 
cooled to 0° in thawing ice, after 
which it was plunged suddenly into 
boiling water, where it remained 
till the inclosed thermometer had 
acquired the heat of 70°, which took 
up no less than 2456 seconds, or 
above 40 minutes; and it had re- 
mained in the boiling water full a 
minute and an half before the mer- 
cury in the thermometer shewed the 
Jeast sign of rising. Having at length 
Cooled, 
ANNUAL REGISTER, 1702. 
that the warmth of a covering de- 
pends not merely upon the fineness 
of the substance of which the cover- 
ing is formed, and the disposition of 
its parts, but that it arises in some 
measure from a certain attraction 
between the substance and the air 
which fills its interstices, l thought 
that an experiment with semen lyco- 
podii might possibly throw some light 
upon this matter; and in this opi- 
nion I was not altogether mistaken, 
as will appear by the results of the 
three following experiments. 
Heated. 
been put into motion, it rose very ra- 
pidly 40 or 50 degrees, after which 
its motion, gradually abating, be- 
came so slow, that it took up 1585 
seconds, or something more than 
26 minutes, in rising from 60° te 
70°, though the temperature of the 
medium in which it was placed dur- 
ing the whole of this time, was very 
nearly 80°; the mercury in the ba- 
rometer standing but little short of 
27 Paris inches. 
All the different substances which 
I had yet made use of in these ex- 
periments 
