86 Properties of Wood Ashes. 
parently across the semiglobule, and continued thus to play.in 
the most lively manner from various points in rapid succession 
until inflammation ensued. This pretty miniature pyrotechny 
can only be seen in the dark. is 
Hygrometric Power of Wood Ashes.*—One hundred grains of 
dried ashes were lightly spread over an area of sixty square inches, 
and were exposed with due caution in the shade for twenty four 
hours, when the noon temperature was 62°, and the air clear and 
calm. Jn this time they gained no weight; continued exposure 
for seventy two hours enabled them to gain..55 of a grain. But 
when the temperature was near the freezing point at noon, they 
frequently gained in eight to twenty four hours from .66 to 1.66 
of a grain. A fine sponge was converted into a sensitive hy- 
grometer by saturating it with a solution of carbonate of potash, 
and drying it at 170°. Thus prepared the sponge gained from. 
thirteen to forty four per cent. more than the ashes, and it assist- 
ed me in making out the following deductions from eighteen ex- 
periments on the hygrometric properties of ashes. 1. They absorb 
atmospheric vapor more yppidly at a low than at a high tempera- 
ture.. 2. They do not cease to act hygrometrically at a tempera- 
ture considerably below the freezing point. 3. The range of per 
centage of increase is from 0 to 1.66. 4. Different parcels 
of ashes possess different degrees of hygrometric power. This 
is owing perhaps to the varying quantity of potash present. 
Carbonaceous Dust in Ashes.—It became interesting to ascer> 
tain how much, if any carbon, in a pulverized state, existed in 
ashes. Hor this purpose I employed sundry rather rude methods, 
now to be mentioned. 1. By pouring a sufficient quantity of 
sulphuric. acid on sifted ashes, to moisten them, much caloric 
was disengaged, and a white paste formed, in which. black parti- 
cles were very obvious. These particles washed and crushed 
between the teeth, produced the peculiar. sensation of breaking 
On diluting this paste with a large quantity of water, 
a milky mixture (sulphate of lime) was obtained, in which the 
black. particles rapidly subsided. All the black sediment, how- 
ever, Was not coal. 2, One thousand grains of sifted ashes were 
a 4 scat 
