Properties of Wood Ashes. 85 
During my inquiries into this subject, I was induced to. com- 
pare the physical and other properties of various powders. Omit- 
ting my tables. of their specific gravity, porosity, &c. as incom- 
plete, I give the other results below. The substances were dried 
at a high temperature, and passed through the same sieve ; the 
ans used in ascertaining the compressibility was sixty pounds. 
‘he gravity was determined by weighing a given measure, 
without compression or jar. 
«© Water, being ’ ’ ; , a3 1000 sichiase 
Magnesia, was. ‘ : , ‘ 164... 
' Ashes, i ‘ i ‘ é ‘ 356 by 
Ss 
he 
Chalk, a ; ‘ . , 582 
» Scorified wood oem P '. vig sate 910 
. Plaster of Paris, . , ; . . 921 
~ Common earth, . -j . ; 1035 
Sand, & ‘ one : 1358 
Compressibility.  ~ : 
The loose measure, being. grat 100 
Ashes were reduced in bulk, to. Sy sinc ode 
Magnesia, . nee mnie Rae teal 
RA 9 a eth ha SNS 
Plaster of Paris, .  . ss AEE 
COPANO AUER ass 2, ee 
ab Scorified ashes, ak lO a 
sin at al 
Sarde Fires au, be Sle EB pa cig Bi Gee i eek tty % Pe eis ee F298, eed ees 
Conductibility—I dtd oenkbacet + pill-boxes of Fantoen 
size, color, é&c. and filled them evenly Seah without jarring, with 
the several powders tested.. On the centre of the surface, I care- 
fully placed very small squares of tin-foil supporting a particle of 
phosphorus. Thus prepared, the boxes were at the same instant 
carefully set upon an equally heated metallic plate, and the time 
of fusion and of deflagration noted. I give, in the subjoined ta- 
ble, the average results of several trials, in seconds. 
hes. |Seorif. ashes.| . Chalk. Earth. | Gypsam, | Sugar. 
M42.335 [112.967| 125.242. 193 203/135, oual77 4 490152 300| 154.314 | 218407 
pe fused, the. phosphorus. assumed a hemispherical form, 
and delicate vivid lines shot like lightning from the margin ap- 
