Every half-hour or so stir the contents of the box with your stick, in order that they may thoroughly amalgamate. Lastly, when the whole is reduced to a thick, creamy-looking liquid, give a final stir, and pour the mixture into your tray, which you will have placed ready to receive it.
Most likely a number of air-bubbles will be floating on the surface of the liquid. These you must get rid of at once, or you will never be able to get off a clear and neat impression.
This part of the business is very easily managed. All that you need do is to heat your needle to a red heat, and touch each bubble in turn with the point. This treatment will cause them to burst, and by the time you have destroyed them all the composition will begin to set. For the next half-hour you must leave it perfectly undisturbed, upon a level surface, and at the end of that time it will be ready for use.
If all has gone well, your graph ought now to present the appearance of a pale yellow slab, yielding and rather clammy to the touch, and with a peculiarly glossy surface. This gloss will vanish after you have taken off your first impression, but that you need not trouble about.
When you wish to make use of your machine, write your letter or circular, or whatever it may be, with the special ink, and take care to make the up and down strokes as nearly as possible of the same thickness throughout. Let the writing dry, without blotting it, and then lay the sheet of paper face downwards upon your graph. Take care that in so doing you get no air-bubbles. If you do the result will be an uneven impression.
Now rub lightly with your finger over the whole of the paper as it lies upon the graph, in order to make sure that every part shall be in actual contact with the composition. Then, after about a minute or so, remove the paper very carefully, lifting it by one corner, and you will see that a reversed copy of the writing—a ‘negative,’ in fact—remains upon the graph.
Without loss of time take another sheet of paper, lay it upon the writing, rub as before, and remove after four or five seconds. An exact copy of the writing will by that time have been transferred to it, and by repeating the process you can take any number of impressions, up to fifty or sixty, that you may happen to want. As soon as you have printed off a sufficient quantity, wash your graph with cold water, rubbing lightly with a piece of clean rag until the writing has almost disappeared. Then dry, and put away until again required for use. If you leave it for any length of time before washing, the ink will sink deeply into the composition. This will not matter once or twice, but if you make a practice of allowing it to do so your graph will in course of time be simply saturated with the ink and will assume a deep violet hue.
The copies which you will have taken will probably have absorbed some of the moisture from the graph and curled up into a kind of spiral form. These you can easily straighten by means of warmth and a little judicious pressure.
After you have used it a few times the surface of your graph will most likely become rough and uneven and unfit for further service. When this is the case, cut the composition out of the tray with an old knife and melt it down afresh. When thoroughly liquid, stir it well, pour it back into the tray, and eradicate the bubbles as before. Do not melt it down in the tray itself. If you do the glycerine will rise to the surface for want of proper stirring, and utterly ruin every sheet of paper you place upon the machine, obliging you to melt down the composition over again before it can be of the least use.