DEFINITION OF TERMS, 



165 



twelve pounds of water, for one hour, or 

 till half the liquid has been evaporated. 

 Strain the decoction through ahairsieve, 

 or linen cloth, and then add the other in- 

 gredients, stir the mixture till the whole is 

 dissolved, more especially the gum, after 

 which, leave it to subside for 24 hours, 

 then decant the ink, and preserve it in 

 bottles of glass, or stoneware, well cork- 

 ed. The following will also make a 

 good ink: to one quart of soft water, add 

 four ounces of galls, one ounce of coppe- 

 ras roughly bruised, and two ounces of 

 gum arabic. Let the whole be kept near 

 the fire a few days, and occasionally well 

 shaken. 



Red writing ink, is made in the fol- 

 lowing manner. Take of the raspings of 

 Brazel wood a quarter of a pound, and in- 

 fuse them two or three days in vinegar. 

 Boil the infusion for an hour over a gen- 

 tle fire, and afterwards filter it while hot. 

 Put it again over the fire and dissolve in 

 it, first, half an ounce of gum arabic and 

 after^vards of alum and white sugar, each 

 half an ounce. 



Printing ink is a black paint, compos- 

 ed of lampblack and linseed or suet oil 

 boiled, so as to acquire considerable con- 

 sistence and tenacity. The art of prepar- 

 ing it is kept a secret, but the obtaining 

 of good lamp black appears to be the 

 chief difficult}^ in making it. 



The ink used by the copper plate prin- 

 ters differs from the last only in the oil 

 not being so much boiled, and the black 

 which is used being Frankford black. 



Sympathetic inks are such as do not 

 appear after they are written with, but 

 which may be made to appear at plea 

 sure, by certain means to be used for that 

 purpose. A variety of substances have 

 been used for that purpose; we will de- 

 scribe the best of them. 



1. Dissolve some sugar of lead in water, 

 and write with the solution. When dry, 

 no writing will be visible. When you 

 want to make it appear, wet the paper 

 with a solution ofalkalinesulphuret (liver 

 of sulphur) and the letters will imme- 

 diately appear, of a brown color; even 

 exposing the writing to the vapors of 

 these solutions will render it apparent. 



2. Write with a solution of gold in 

 aqua-regia, and let the paper dry gently 



in the shade. Nothing will appear; but 

 draw a sponge over it wetted with a so- 

 lution of tin in aqua-rcgia, the writing 

 will immediately appear of a purple co- 

 lor. 



3. Write with an infusion of galls, and 

 when you wish the writing to appear, 

 dip it into a solution of green vitiiol; 

 the letters will appear black. 



4. Write with distilled sulphuric acid, 

 and nothing will be visible. To render 

 it so, hold it to the fire, and the letters 

 will instantly appear black. 



5. Juice of leinons, or onions, a solu- 

 tion of sal-ammoniac, green vitriol, &c.,. 

 will answer the same purpose, though 

 not so easily, nor with so little heat. 



6. Green sympathetic ink. — Dissolve 

 cobalt in nitro-muriatic acid, and write 

 with the solution. The letters will be 

 invisible till held to the fire, when they 

 will appear green, and will disappear 

 completely again, when removed into the 

 cold. In this manner they may be made 

 to appear and disappear at pleasure. 



A very pleasant experiment of this 

 kind is to make a drawing representing 

 a winter scene, in which the trees appear 

 void of leaves, and to put the leaves on 

 with this sympathetic ink; then, upon 

 holding the drawing near to the fire, the 

 leaves will begin to appear in all the ver- 

 dure of spring, and will very much sur- 

 prise those who are not in the secret. 



Blue sympathetic ink. — Dissolve co- 

 balt in nitric acid; precipitate the cobalt 

 by potass; dissolve this precipitated oxide 

 of cobalt in acetic acid, and add to the 

 solution one-eighth of common salt; this 

 will form a sympathetic ink, that, when 

 cold, will be invisible, but will appear 

 blue by heat. 



On t/ie composition of a new Indeli- 

 ble writing ink, by Dr. Traill. — To pre- 

 pare the ink, the inventor directs that 

 the gluten of ivheat be separated from 

 the starch as completely as possible, by 

 the usual process, and when recent, to be 

 dissolved in pyroligneous acid with the 

 aid of heat; this forms a saponaceous 

 fluid, which is to be tempered with water 

 until the acid has the usual strength of 

 vinegar. He grinds each ounce of this 

 fluid with from eight to ten grains of the 

 best lamp black, and one and a half 



