JAPAN DRIER. 19 



the temperature of the bath at which distillation begins, and continue distilla- 

 tion at a temperature of 185 C. in the oil bath, finally raising the temperature 

 to 200 C. This method generally tends to give lower results on volatile oils 

 than the steam distillation method; but the distillate can be tested for water- 

 soluble volatile liquids, which would be lost by the steam distillation. 



6. Fixed Oil and Gums. 



The percentage of fixed oil and gums is obtained by subtracting the percent :ig<- 

 of volatile oils from 100. A check upon this determination is obtained by weigh- 

 ing the residue from the dry distillation. 



7. Acid Number. 



Determine the acid number in the usual way, using 10 grams of varnish. 



8. Rosin. 



After getting the acid number, decant the alcohol, evaporate, and apply the 

 Liebermauu-Storch test for rosin (page 16). 



9. Ash. 



Determine the ash in 10 grams, using a quartz or porcelain dish and carrying 

 out the determinations at a low heat, best in the muffle. Determine the reac- 

 tion of the ash to litmus paper and make a qualitative analysis. It is fre- 

 quently well to make a quantitative determination of lime, a large amount of 

 which indicates rosin. It is sometimes advisable to determine the percentage 

 of lead and manganese. Some lead will, however, be lost in the ashing, and if a 

 correct lead determination is required, follow the method described for mixed 

 paint vehicles (page 41). 



10. Miscellaneous. 



It is not possible from such an examination as has just been described to de- 

 cide on the value of a varnish for any particular purpose, though valuable in- 

 formation as to the materials used in its manufacture may be obtained. An 

 examination of the varnish film should, therefore, always be made. The films 

 are best made by flowing the varnish on carefully cleaned plates of glass, and 

 allowing to dry at room temperature in a vertical position. Observe the time 

 of setting and the nature of the film after twenty-four hours, noting the trans- 

 parency, hardness, elasticity, tendency to dust by scratching, etc. After thor- 

 ough drying, immerse the plate in water over night, dry, and note appearance. 

 The working quality of a varnish must be determined by application on wood, 

 and it is best to make this test on well seasoned and perfectly smooth white 

 pine. Apply a thin coat of the varnish to wood and allow to dry, sandpaper 

 down smooth, and then apply the coat to be tested. Observe how the varnish 

 works under the brush, character of coat, etc. This panel, after drying, may 

 be used for further testing as to whether the varnish will stand rubbing, etc. 



JAPAN DRIER. 



The analysis of Japan drier is conducted in the same way as that of varnish. 

 The following specifications for Japan drier for the Philadelphia and Reading 



