A Secret Correspondence By Means Of Invisible Ink
A person wishing to carry on a correspondence with another, and who is
fearful of having his letter opened, or intercepted, can adopt the
following plan:
Write any unimportant matter with common ink, and let the lines be
very wide apart: then between these lines write the communication you
wish to make, with any of the above invisible inks you can most
readily procure.
Your correspondent is to be previously apprized of the method of
making the characters visible: and writing in common ink will serve to
lull the suspicions of those who might intercept the letter, and who,
not finding any thing important in it, will either forward or keep it.
In either case there can be no danger, as the writing will not be
visible without the proper application.
More
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A Fountain Which Acts By The Heat Of The Sun
In the annexed engraving, Fig. 7, G N S is a thin hollow globe of copper, eighteen inches diameter, supported by a small inverted basin, placed on a stand with four legs, A B C D, which have between them, at the bottom, a basin of two feet diameter.... A Hundred Different Names Being Written On The Cards To Tell The
particular Name any Person thought of. Write on ten cards a hundred different names, observing that the last name on each card begins with one of the letters in the word INDROMACUS, which letters, in the order they stand, answer the numbers 1 to 10... A Lamp That Will Burn Twelve Months Without Replenishing
Take a stick of phosphorus, and put it into a large dry phial, not corked, and it will afford a light sufficient to discern any object in a room when held near it. The phials should be kept in a cool place, where there is no great current of air, an... A Liquid That Shines In The Dark
Take a bit of phosphorus, about the size of a pea; break it into small parts, which you are to put into a glass half full of very pure water, and boil it in a small earthen vessel, over a very moderate fire. Have in readiness a long narrow bottle, w... A Luminous Bottle Which Will Show The Hour On A Watch In The Dark
Throw a bit of phosphorus, of the size of a pea, into a long glass phial, and pour boiling oil carefully over it, till the phial is one-third filled. The phial must be carefully corked, and when used should be unstopped, to admit the external air, a... A More Powerful Fulminating Powder
The most wonderful instance of chemical detonation is formed by the combination of volatile alkali with silver. Gunpowder, or fulminating gold, are not to be compared with this invention, and the great danger attending its manufacture prevents us fr... A Person Having An Even Number Of Shillings In One Hand And An Odd
Number in the other, to tell in which hand the odd or even Number is. You desire the person to multiply the number in his right hand by an odd figure, and the number in his left by an even one; and tell you if the products, added together, be odd or... A Person Having Put A Ring An One Of His Fingers To Name The Person
the Hand, the Finger, and the Joint on which it is placed. Let a third person double the number of the order in which he stands who has the ring, and add 5 to that number; then multiply that sum by 5, and to the product add 10. Let him next add 1 to... A Powder Which Catches Fire When Exposed To The Air
Put three ounces of rock alum, and one ounce of honey or sugar, into a new earthen dish, glazed, and which is capable of standing a strong heat; keep the mixture over the fire, stirring it continually till it becomes very dry and hard; then remove i... A Sea-fight With Small Ships And A Fire-ship
Having procured four or five small ships, of two or three feet in length, make a number of small reports, which are to serve for guns. Of these range as many as you please on each side of the upper decks; then at the head and stern of each ship fix ... A Secret Correspondence By Means Of Invisible Ink
A person wishing to carry on a correspondence with another, and who is fearful of having his letter opened, or intercepted, can adopt the following plan: Write any unimportant matter with common ink, and let the lines be very wide apart: then bet... A Vessel That Will Let Water Out At The Bottom As Soon As The Mouth
is uncorked. Provide a tin vessel, two or three inches in diameter, and five or six inches in height, having a mouth about three inches in width; and in the bottom several small holes, just large enough to admit a small needle. Plunge it in water w... A Water To Give Any Metal A Gold Colour
Take fine sulphur and pulverize it; then boil some stale spring water; pour it hot upon the powder, and stir it well together; boil it again, and pour into it an ounce of dragon's blood. After it is well boiled, take it off, and filter it through a ... A Water Which Gives Silver A Gold Colour
Take sulphur and nitre, of each an equal quantity; grind them together very fine, and put them into an unglazed vessel; cover and lute it well; then set it over a slow fire for 24 hours; put what remains into a strong crucible, and let it dissolve; ... Account Of The Wonderful Effects Of Two Immense Burning-glasses
Mr. de Tschirnhausen constructed a burning-glass, between three and four feet in diameter, and whose focus was rendered more powerful by a second one. This glass melted tiles, slates, pumice-stone, &c., in a moment; pitch, and all resins, were melte... Aerial Bubbles
Take a stone, or any heavy substance, and putting it in a large glass with water, place it in the receiver. The air being exhausted, the spring of that which is in the pores of the solid body, by expanding the particles, will make them rise on its s... Aigrettes
Mortars to throw aigrettes are generally made of pasteboard, of the same thickness as balloon mortars, and two diameters and a half long in the inside from the top of the foot: the foot must be made of elm without a chamber, but flat at top, and in ... Alarum
Against the wall of a room, near the ceiling, fix a wheel of twelve or eighteen inches diameter; on the rim of which place a number of bells in tune, and, if you please, of different sizes. To the axis of this wheel there should be fixed a fly to re... Alternate Illusion
With a convex lens of about an inch focus, look attentively at a silver seal, on which a cipher is engraved. It will at first appear cut in, as to the naked eye; but if you continue to observe it some time, without changing your situation, it will s... Another
Dissolve bismuth in nitrous acid. When the writing with this fluid is exposed to the vapour of liver of sulphur, it will become quite black. ... Another
Dissolve green vitriol and a little nitrous acid in common water. Write your characters with a new pen. Next infuse small Aleppo galls, slightly bruised in water. In two or three days, pour the liquor off. By drawing a pencil dipped in this sec... Another
If you put a tea-spoonful of a liquor composed of copper infused in acid of vitriol, into a glass, and add two or three table-spoonfuls of water to it, there will be no sensible colour produced; but if you add a little volatile alkali to it, and sti... Another
Put half a tea-spoonful of a liquor composed of iron infused in acid of vitriol, into half a glass of water; and add a few drops of phlogisticated alkali, and a beautiful Prussian blue will appear. ... Another Curious Experiment With Oil And Water
Drop a small quantity of oil into water agitated by the wind; it will immediately spread itself with surprising swiftness upon the surface, and the oil, though scarcely more than a tea-spoonful, will produce an instant calm over a space several yard... Another Electric Orrery See Page 92
From the prime conductor of an electric machine suspend six concentric hoops of metal at different distances from each other, in such a manner as to represent in some measure the proportional distances of the planets. Under these, and at a distance ... Another Invisible Green Ink
Dissolve zaffre, in powder, in aqua regia, for twenty-four hours. Pour the liquor off, and the same quantity of common water, and keep it in a bottle well corked. This ink will not be visible till exposed to the fire or the sun; and will again be... Another Method
Artificial coruscations may also be produced by means of oil of vitriol and iron, in the following manner:--Take a glass vessel capable of holding three quarts: put into this three ounces of oil of vitriol, and twelve ounces of water, then warming t... Another Method
Put a small quantity of phosphorus and some potash, dissolved in water, into a retort; apply the flame of a candle or lamp to the bottom of the retort, until the contents boil. The phosphuretted hydrogen gas will then rise, and may be collected in r...