217 
on naphthaline. 
abundantly deposited in short acicular crystals aggregated in 
stelliform groups. These crystals pressed between folds of 
unsized paper, in order to separate the adhering acid, and 
then exposed to heat, are readily melted : in cooling, the 
melted mass shows evident traces of acicular crystallization, 
and the crystals are of a yellow colour. This yellow sub- 
stance is readily inflamed, burns with a bright flame, emits 
much smoke, and leaves a considerable residuum of carbon. 
Of all the characters of the white concrete substance de- 
scribed in this section, its ready disposition to crystallize is 
perhaps the most remarkable. 
If thrown into a red hot crucible, a dense white vapour 
arises from it ; which being received into a bell glass placed 
over the crucible, is condensed round the lower part of the 
glass in the form of a white powder; but in the upper and 
cooler part of the glass distinctly crystalline plates are formed, 
of a beautiful silvery lustre. 
A similar and equally beautiful crystallization may be ob- 
tained by boiling this substance in water, in a glass matrass 
having a long neck ; in the upper part of which crystals will 
be formed and deposited during the boiling. 
If exposed to a degree of heat not more than sufficient to 
melt it under a bell glass, the vapour that rises from it crys- 
tallizes before it reaches the surface of the glass, and flies 
about the interior with exactly the appearance of a shower of 
minute particles of snow. 
If a piece of cotton twine be coiled up like the wick of a 
candle, and after having been dipped in this substance while 
melted, be set on fire for a second or two, and then blown 
