148 COMPOSITION OF DURABLE INK. 



the paper, if a vehicle can be found which will diflblve a fuffi- 



cient quantity, and which, when the colouring matter is alfo 



added, {hall be fluent enough in writing. 



but is not alto- Oil of lavender will diflblve copal. I have made fome ex- 

 gcther free from . . . . r . , J , , . . r . 



inconvenience. p e "ments with thele articles, and the combination lucceeds 



fo well, that I have not been inclined to ufe any other. The 



only inconvenience to be apprehended from the ufe of copal 



in the composition of ink, is, from its being foluble at a low 



temperature ; but whether any other kind of tenacious matter 



of more difficult folubility, can be ufed conveniently in writing, 



I muft leave to future difcuflion. The folution of a fubflance 



which could only be diflblved in an high temperature, would 



certainly be the mod proper vehicle to prevent alteration ; 



for, after the deliccation of the writing, it would be difficult to 



foften the ink in one part of a manufcript, without expoling 



the whole to a very injurious procefs. 



Compofition of Ink may be compofed of oil of lavender, copal, and lamp 



lavender copal D ^ ac ^* according to the following proportions of the ingre- 



and lamp black, dients : 



Take of oil of lavender, 200 grs. copal in powder, 25 grs. 

 lamp black from 2\ to 3 grs. With the afliftance of a gentle 

 heat, diflblve the copal in the oil of lavender in a fmall glafs 

 phial, and then mix the lamp black with the folution upon a 

 marble flab, or other fmooth furface. Put the compofition 

 into the bottle, and keep it excluded from the air. After a 

 repofe of fome hours, the ink muft be well fliaken and ftirred 

 with a piece of wire before it is ufed ; if it be too thick, it 

 muft be diluted with a little oil of lavender, oil of turpentine, 

 or alcohol. The facility of writing with this compofition de- 

 pends much on the quantity of the colouring matter. Three 

 grains of lamp black to two-hundred and twenty-five of the 

 folution of copal, producing ink of a full body of colour, and is 

 nearly as much as the copal can protect from injury after the 

 diflipation of the oil of lavender. Two grains and an half of 

 lamp black, and half a grain of indigo, produces ink of a paler 

 colour, but which may be diftributed upon the paper with the 

 facility of common ink. A piece of fponge *, or other or- 

 ganized 



* The cuftom of putting cotton in an inkftand has been difufed, 



more particularly, I think, fince an inkftand, invented by the late 



worthy and ingenious Samuel More, of the Society of Arts, was 



4 made 



