210 
Dr. Kidd’s observations 
other instances these cylinders were removed, and their place 
supplied by sand, or by pieces of well burnt coke, or by 
pieces of brick ; but it was found that the interstices between 
the cylinders, or between the particles of sand, &c. were so 
soon choaked up with carbon from the decomposition 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 
condensed ; and at the end of every experiment this con- 
densing vessel was found to contain an aqueous fluid having 
an ammoniacal odour, and a dark coloured liquid, resem- 
bling tar in appearance. 
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 
