J56 •" COPAL VARWUHEJJ, 



fpirit of turpentine in his country are very different from ih& 

 fubftances which are fold hy the fame names in this. 

 General My intention in communicating thofe papers to the Society 



Ttmir . ^^g j^ ^^^ thofe who are engaged in the practice of the arts, 



by making public a method of making a vainifti that muft be 

 valuable to them : and I have been induced to trouble you with 

 this, in hopes that, by printing it, you may prevent thofe falfe 

 notions, which might be formed upon Mr. Tingry's experi- 

 ments from gaining credit; to which you will allow me to add 

 fuch hints and improvements as may prevent difappomtment to 

 thofe who undertake to prepare this varnifli for themfelves in- 

 ilead of depending upon thofe who make it for fale ; this every 

 artift (hould do if he refolves to have it perfect ; for, though 

 I do not mean to fuppofe that every maker of varnith will fub- 

 ftitute inferior articles, yet it is certain ihat where the price of 

 cne article is higher, becaufe it is really valuable, and difficult 

 to make, many dealers will fubftitute fomething inferior that 

 produces more profit to himfelf, without confidering whether 

 it may not be injurious to thofe who are to ufe it. 

 Narrative of an J had feveral times given fome of my varnifh to an artift, 

 not fJc'^eedln who liked it fo well that he requeued I would inftruft him to 

 the procefb. make it himfelf, inftead of making frequent applications to me 

 for it : I procured him the neceflary apparatus, and gave him a 

 written account of the procef*, with fuch verbal inllrudions 

 as I could add to it, and left him to procure his own materials 

 and proceed to work by himfelf; he did fo, and did not fuc- 

 ceed in dilTolving the copal ; he tried a fecond and third time 

 with no more fuccefs; he then brought his materials to me, 

 requefted that I would try if I could diflfolve them ; which ex- 

 periment would determine whether his materials were bad, or 

 whether there was any defedl in his manner of attempting the 

 procefs : this I refolved to undertake; ufing the fame fpirit 



fpirit I ufed had by chance obtained thofe powers fordiflTolvrng copal 

 which he endewvaurs to give it by timsy &c. is perfeftly ridiculous. 

 You and yoor Englifli readers will know that in faying I did not 

 fucceed when I ufed fpirit of turpentine from the colour /hops, but 

 always did when I got the fpirit from Apothecaries Hall, I meant 

 that at the latter place I always obtained the beft article of the kind, 

 inftead of the inferior ariicles which are fold by the fame ?iame in 

 other places, though totally unfit for this purpofe. 



4nci 



