Observations on Naphthaline. 9 
the mode by which it may be obtained, or of its relation to the 
substance from which it is produced; on which account I have 
been induced to offer to the Royal Society the following obser- 
vations respecting these points of its history. 
In the experiments which led, in the present instance, to the 
detection of the substance in question, it was proposed to effect 
the decomposition of coal tar, by passing its vapour through an 
ignited iron tube; and, in order to increase to the utmost the 
extent of the ignited surface, that portion of the tube which was 
constantly kept up to a red heat, was filled, in the first instance, 
with a series of hollow iron cylinders open at both extremities, 
and successively decreasing in diameter, so as to be included one 
within another. In other instances these cylinders were re- 
moved, and their place supplied by sand, or by pieces of well 
burnt coke, or by pieces of brick 3 but it was found that the in- 
terstices between the cylinders, or between the particles of sand, 
&c. were so soon choked up with carbon from the decomposi-, 
tion of the tar, as to be rendered absolutely impervious to the 
gas produced during the decomposition ; so that it became ne- 
cessary to pass the vapour of the tar simply through the tube 
itself, 
Connected with the tube in which the tar was decomposed 
was a vessel, in which any undecomposed vapour of the tar, or 
any products resulting from its decomposition, might be con- 
densed; and at the end of every experiment this condensing 
vessel was found to contain an aqueous fluid having an ammo- 
niacal odour, and a dark coloured liquid resembling tar in ap- 
pearance. 
This dark coloured liquid is characterized by the following 
properties : 
Its colour, in the mass, is black; but when spread in a thin 
stratum on paper or glass, it is of a clear deep reddish brown 
colour. 
It is a much thinner liquid than the coal tar from which it 
was produced; and has a peculiar and slightly aromatic odour, 
together with the smell of ammonia; about three-fourths of a 
given quantity of it pass through unsized paper; and that which 
remains on the paper resembles common tar. Sp. gr. 1050; 
the sp. gr. of the tar from which it was produced being 1109. 
Readily and entirely soluble in ether. 
Soluble, but not entirely, in alcohol; the solution becoming 
milky upon the addition of water, and this milky mixture passing 
unaltered through the pores of the closest filtering paper. 
Not miscible with water; but readily communicating to it a 
light brown colour, and a taste at first sweet, but followed by an 
aromatic pungency. The water acquires alkaline properties, and 
Vol, 59, No, 285, Jan. 1822. B holds 
