第109章

"One of the outer bandages was of a reddish color, which dye I found to be vegetable, but could not individualize it; Mr. T. J. Herapath analyzed it for tin and alumina, but could not find any.

The face and internal surfaces of the orbits had been painted white, which pigment I ascertained to be finely powdered chalk.""I am a scribbled form, drawn with a Pen Upon a Parchment, and against this fire Do I shrink up."--KING JOHN, v, 7.

"With much ado, his Book before him laid, And Parchment with the smoother side display'd;He takes the Papers, lays 'em down agen, And with unwilling fingers tries his Pen;Some peevish quarrel straight he tries to pick, His Quill writes double, or his Ink's too thick;Infuse more Water; now 'tis grown too thin, It sinks, nor can the characters be seen."--Persius, translated by Dryden.

INKS CALLED SYMPATHETICAL (Seventeenth Century).

"These operations are liquors of a different nature, which do destroy one another; the first is an infusion of quick-lime and orpin; the second a water turn'd black by means of burned cork; and the third is a vinegar impregnated with saturn.

"Take an ounce of quick-lime, and half an ounce of orpin, powder and mix them, put your mixture into a matrass, and pour upon it five or six ounces of water, that the water may be three fingers breadth above the powder, stop your matrass with cork, wax, and a bladder; set it in digestion in a mild sand heat ten or twelve hours, shaking the matrass from time to time, then let it settle, the liquid becomes clear like common water.

"Burn cork, and quench it in aqua vitae, then dissolve it in a sufficient quantity of water, wherein you shall have melted a little gumm arabick, in order to make an ink as black as common ink. You must separate the cork that can't dissolve, and if the ink be not black enough, add more cork as before.

"Get the impregnation of saturn made with vinegar, distilled as I have shewn before, or else dissolve so much salt of saturn as a quantity of water is able to receive: write on paper with a new pen dipt in this liquor, take notice of the place where you writ, and let it dry, nothing at all will appear.

"Write upon the invisible writing with the ink made of burnt cork, and let it dry, that which you have writ will appear as if it had been done with common ink.

"Dip a little cotton in the first liquor made of lime and orpin, but the liquor must be first settled and clear; rub the place you writ upon with this cotton and that which appeared will presently disappear, and that which was not seen will appear.

ANOTHER EXPERIMENT.

Take a book four fingers breadth in bigness, or bigger if you will: write on the first leaf with your impregnation of saturn, or else put a paper that you have writ upon between the leaves; turn to t' other side of the Book, and having observed as near as may be the opposite place to your writing, rub the last leaf of the book with cotton dipt in liquor made of quick-lime and orpin, nay and leave the cotton on the place clap a folded paper presently upon it, and shutting the book quickly, strike upon it with your hand four or five good strokes; then turn the book, and clap it into a press for half a quarter of an hour; take it out and open it, you'll find the place appear black, where you had writ with the invisible ink. The same thing might be done through a wall, if you could provide something to lay on both sides, that might hinder the evaporation of the spirits.

REMARKS.

"These operations are indeed of no use, but because they are somewhat surprizing, I hope the curious will not take it ill, that I make this small digression.

"It is a hard matter to explicate well the effects Ihave now related, nevertheless I shall endeavour to illustrate them a little, without having recourse to sympathy and antipathy, which are general terms, and do not explicate nothing at all; but before I begin, we must remark several things.

"The first is, that it is an essential point to quench the coal of cork in aqua vitae, that the visible ink may become black with it.

"Secondly, that the blackness of this ink does proceed from the fuliginosity or sooty part of the coal of the cork which is exceeding porous and light, and that this fuliginosity is nothing but an oil very much rarefied.

"Thirdly, that the impregnation of saturn, which makes the invisible ink, is only a lead dissolved, and held up imperceptibly in an acid liquor, as I have said, when I spoke of this metal.

"Fourthly, that the first of these liquors in a mixture of the alkali and igneous parts of quick-lime with the sulphureous substance of arsenick; for the orpin is a sort of arsenick, as I said before.

"All this being granted, as no body can reasonably think otherwise, I now affirm, that the reason why the visible ink does disappear, when the defacing liquor is rubbed upon it, is that this liquor consisting of an alkali salt, and parts that are oily and penetrating, this mixture does make a kind of soap, which is able to dissolve any fuliginous substance, such as burnt cork, especially when it has been already rarefied and disposed for dissolution by aqua vitae, after the same manner as common soap, which is compounded of oil, and an alkali salt, is able to take away any spots made by grease.

"But it may be demanded, why after the dissolution the blackness does disappear.

"I answer, that the fuliginous parts have been so divided, and locked up in the sulphureous alkali of the liquor, that they are become invisible, and we see every day that very exact solutions do render the thing dissolved imperceptible, and without colour.

"The little alkali salt which is in the burnt cork may also the better serve to joyn with the alkali of the quick-lime, and to help the dissolution.