Capnomor. 
247 
kept which are heavier than water. To remove the acetic 
acid, the product is to be mixed with carbonate of potash, 
till no effervescence is produced. The oil is to be separated 
and mixed with a cold solution of caustic potash of a specific 
gravity of about 1.20, stirring the mixture well. If it becomes 
solid on standing, (owing to the presence of a large proportion 
of picamar,) it is to be liquified by exposure to heat. All 
that is not dissolved on a second treatment with the potash is 
to be rejected. The alkaline solution is now to heated in an 
open vessel, the heat being slowly increased till ebullition is 
produced, which is to be permitted for a few instants only, 
when the fire is to be allowed to go out ; after the fluid is 
cold it is to be decomposed by a slight excess of diluted sul- 
phuric acid ; this sets free a large quantity of a brownish black 
oil. It is now to be poured into a retort, and so much of the 
solution of caustic potash added as to render the mixture 
alkaline, and the whole distilled, but not to dryness. The 
product of the distillation, which is oily, transparent, and of 
a pale colour, is to be dissolved in a solution of caustic pot- 
ash of a specific gravity of about 1.16, and the above process 
repeated ; that is, the undissolved portion is to be rejected, 
the solution heated to ebullition in an open vessel, permitted 
to cool, diluted sulphuric acid added, the oil separated, potash 
added till the fluid is rendered alkaline and the distillation re- 
peated. These operations are to be renewed several times, 
diminishing the strength of the solution of potash at each re- 
petition to 1.12, 1.08, 1.05. Each time a residue of insoluble 
oil is obtained in the alkaline solution, and it is these resi- 
dues that contain the substance under consideration, but the 
two last in the state of the greatest purity, and hence they 
only should be used to obtain it. As they retain a portion of 
creosote, a solution of potash of a specific gravity of 1.20 is 
to be added to them, the mixture well stirred, permitted to 
settle, decanted and distilled. The product of the distillation 
is colourless, and it is to be mixed with great precaution, 
very gradually, and constantly stirring, with an equal volume 
of fuming sulphuric acid ; the mixture becomes somewhat 
