Morey on Heat and Light. 123 
the wood adjoining them has been converted into coal.— 
These streams of vapor appear to me to be very different 
from those of the Carburetted Hydrogen, which are often 
seen issuing from burning wood after it has become nearly 
coal. ‘These rarely, if ever, go out, and the flame follows 
them to the wood. Not so with those of the vapor: they 
are plainly to be seen issuing to some distance, and mixing 
generally with a proportion of air, before they will burn; 
and they are often extinguished by puffs of too great a pro- 
portion of steam. The colour of these vapors, their deto- 
nating noise, their variously coloured flames—(blue, blue 
and white, white and intense white) we can now perfectly 
imitate at our pleasure with the patent lamp stove, by burn- 
ing tar, pitch pine, or mineral coal and water. 
One of the greatest difficulties which I have met with, 
was from the inclination the tar or rosin manifests, to over- 
flow or run out, when heated to about the temperature of 
boiling water; this disposition arises undoubtedly from the - 
sudden conversion of the water, contained in every part of 
the tar, into steam. The best mode I have tried of obvi- 
ating the difficulty is, by filling the vessel only in part—say 
ene quarter with tar, and then filling it with small or fine 
coal.* ‘The effect appears to be, that the tar, as it becomes 
heated at the sides of the vessels, rises up and passes off 
laterally into the centre of the coal, in a geat measure out of 
the reach of the high temperature at the sides; when the 
bubbles are broken, the vapor passes up through the coal, 
and the tar settles down, to repeat the same operation. This 
experiment may in some measure be easily tried bya common 
skillet. Fill it about one quarter with tar; place live coals 
around it, and in a few minutes the tar will fow over: but, 
if previously fine coal be added so as nearly to fill the skil- 
let, it cannot be made to flow over with a common charcoal 
fire, unless urged by a strong blast. When the vapor rises 
pretty freely above the coal, and if a flame is applied, it takes 
fire and will continue to burn while the tar lasts.—If a piece 
of coal of some size be made a little concave and placed at 
the top in the centre, and a little water poured into it, it re- 
mains a considerable time, although enveloped in flame: 
and is evaporated without boiling. ‘The flame around this 
* We take it for granted that charcoal is intended.— Editor. 
