64 



WOOD TURPENTINES. 



Remarks. For a comparative test with pure gum turpentine as to suitability 

 for varnish making. 



I. CHEMICAL TESTS. 



DISTILLATION TEST. 



Boiling point. 



i About. 



II. Varnish-making tests. Solvent power was tested by mixing 10 parts of 

 each sample (also of gum turps.) with 1 part of a hard gum varnish. The 

 pure turpentine precipitated the gum within one-half hour ; No. 2 followed very 

 shortly; then No. 5 (after about 6 hours). No. 4 held the varnish in solution, 

 showing only a slight separation at the surface edges after a week ; No. 3 held 

 the varnish in solution perfectly for more than two months. 



Other qualities were tested by reducing equal weights of the gum and oil 

 from an agricultural varnish taken from the same batch, with equal volumes 

 of the samples, as well as with pure turpentine, in such a way as to have all 

 conditions as nearly as possible the same. The varnishes so made were not 

 filtered, but were allowed to settle and age for three months. The percentage 

 of volatile matter was then determined and the varnish was submitted to the 

 usual tests of body, flowing, drying, brushing, etc. 



The percentages of volatile matter were: For (I) varnish made with gum 

 turps., 53.50; (II) No. 2, 54.87; (III) No. 3, 52.35; (IV) No. 4, 53.32; (V) No. 

 5, 54.10. The gum turp. varnish was the same in "body" as IV (as shown by 

 the rate of rise oft lie air bubble in a narrow test tube of the varnish) ; II and 

 V were both slightly lighter in body, as would be expected from the higher 

 percentage of volatile matter; but on the other hand III was still thinner, 

 though showing less volatile. This fact is doubtless due to the much greater 

 solvent power of turpentine No. 3, which results in a much less viscous solution. 



Varnish IV showed the poorest flowing qualities; V was slightly better; I 

 and II (in order) still better; and III much the best. The drying test shows 

 that the varnishes with lighter body dry faster and harder, though II, in dry- 

 ing faster than III, shows an exception. The relative order is II first, III, V. 

 IV, I. From a consideration of factors involved it is evident that if all were 

 brought to the same body II, V, and VI would dry at about the same rate, 

 followed by III and I. 



In brushing qualities varnish I was ranked first, V next, III next, followed 

 by IV and II. This ranking denotes the comparative ease with which a smooth, 

 glossy film of proper thickness can be obtained upon a filled board. 



The results of the tests may then be summarized as follows : 



The samples are all stronger solvents than gum turpentine, No. 3 being the 

 'strongest; No. 2 and No. 5 only slightly better than the gum spirits. If odor 

 could be disregarded, No. 3 would probably be in all respects the best substi- 

 tute for gum spirits and would be an improvement on it in some ways; but 



