420 VEGETABLE SUBSTANCES. 



procurement of this illuminating gas direct from the 

 resin without any intermediate distillation. This 

 latter plan is now partially pursued. 



Oil of turpentine is of essential use in varnish 

 making. It forms the great solvent for all resins, 

 and being extremely volatile when exposed to the 

 air, it quickly separates from the varnishing substance, 

 leaving this fixed to the surface whereon the mixture 

 has been applied. 



The most extensive use by far to which oil of tur- 

 pentine is put, is that of diluting oil colours to such a 

 consistency that they will How freely from the painter's 

 brush. For this purpose it is admiralty fitted by 

 the same volatile quality which renders it useful to 

 the varnisher. Without some substance which could 

 be made temporarily to combine with, without acting 

 upon oil colours, liquefying them to the necessary 

 degree, and leaving them again quickly after their 

 application and consequent exposure to the air, it 

 would be impossible to avail ourselves of the great 

 advantages attending the use of colours ground in 

 oil. With the exception of turpentine, there is not 

 any substance known that would fulfil these offices, 

 and which could at the same time be obtained at a 

 price that would render them practically useful. 



Turpentine, previous to its distillation, dissolves 

 totally in alcohol, but the essential oil is very difficult 

 of solution in a spirituous menstruum. One part may 

 be dissolved in seven parts pure alcohol; but on 

 standing a while, the greatest part of the oil sepa- 

 rates and falls to the bottom. Oil of turpentine is a 

 limpid white fluid of a peculiarly powerful smell. It 

 is highly inflammable. 



Its boiling point is 316 degrees of Fahrenheit's 

 scale. 



