228 07? AMBER VARNISH AND ACTD. 



quired the proper degree of fluidity, a great deal of succi- 

 nic acid was given out. 

 No advantage Every person, who has made it, must have had the op- 

 has been made portunity of observing the same thing; but whether from 

 not knowing the true nature and properties of this salt, or 

 from considering it as essential to tiie goodness of the var- 

 nish, no one, at least that I know of, has thought of turn- 

 Amber in var- ing it to advantage. It would be a mistake however to 

 be touUy de-''^ conclude, that good varnish ought to be free from succinic 

 privcdof its acid: on the contrary it is very probable, that at the time 

 atid, when the drying oil and oil of turpentine are added, to in- 



crease the iiuidity of the amber, this substance is stili capa- 

 ble of furnishing it, and even in some quantity. 

 Much of the I should be wandering from the purpose of this Dotice, if 



aru. ObUn the j ^^^.^ ^ (Jetail the various processes employed for the pre- 

 common way . , . ^ i j r 



oi muklng. paratioii of this varnish. 1 shall oniy say, that, as the 

 process is most comKionly conducted on an open fire, and 

 in an open glazed earthen vessel, the mouth of \yhich is 

 four or five inches in diameter, when the matter is suffi- 

 ciently heated, part of the acid set free is carried oif and 

 lost in the air, while a tolerable quantity adheres to the 

 sides of the matrass in the form of very slender needles, 

 sufficiently white to require no purification *. 

 1-|ib. of amber Every matrass containing 24 oz., which is the common 

 v\l\ yield 80 or quantity, may furnish 80 or 90 grains of acid, without any 

 without detri- injury to the quality of the varnish : a fact of which 1 have 

 ment. satisfied myself by several trials made in my own labora- 



tory, as well as in that of Mr. Tonnelier, coach painter. 

 Proper time of who is well skilled in the subject. It is proper to observe 

 eoiiiecting it. j^ere, that we ought to collect the succinic acid as it is sub- 

 limed, which takes place a little before the addition of the 

 oxigenized or drying oil. If tl/is operation were deferred, 

 the greater part of it would be lost. In fact, the motion 

 • of the spatula necessary to mix the oil with the amber 

 would separate a great deal of the acid : and there is no 



Add pure in a * The acid obtained is sufficiently pure when the vessel is new, but 

 new vessel. it is more coloured in subsequent operations. It may then be purified 

 CopLer best. • according to the method indicated by Pott. The artists who use cop- 

 per matrasses will find an advantage in it, for those vessels being 

 more easily cleaned, they will continue t© #:ausii ih« same prpduct, 



hope 



