PAINT OILS AND THINNEItS 



19 



used in the manufacture of many lacquers as well as for thinning 

 down oil-gum varnishes. 



REQUISITE CONSTANTS OF PURE GUM TURPENTINE 



Color Water White 



Specific Gravity at 15 C. . .8G2-.875 



Boiling Point About 156 C. 



Distillation 95% should distil between 153 and 105 C. 



Residue on Evaporation . . . Not over 2% 



Polymerization Not over 5% should remain unpolymerized at 



end of half hour 



Flash-Point Over 40.5 C. 



Spot Test No grease spot should remain when dropped on 



paper and allowed to evaporate 

 Water . . . None 



Wood Turpentine. High-grade wood turpentine is now pro- 

 duced by the steam distillation of finely cut fat pine wood. The 

 lower-grade qualities are often produced from the destructive 

 distillation of sawdust, stumpage, etc., and these products, on 

 account of their content of formaldehyde, are objectionable in 

 odor. In the steam distillation process, however, a high quality 

 product is obtained by cutting out the heavy fractions and re- 

 distilling the lower and purer fractions. It has a high oxidizing 

 value, causing the rapid drying of paints and varnishes to which 

 it has been added. Its solvent value is often greater than that of 

 gum turpentine. When properly refined it has a sweet smell and 

 is to be highly recommended. 



Analyses of samples of pure wood turpentine which have come 

 to the writer for examination follow: 



