You will perhaps here call to mind what I have told you about the pungent smell of our working fluid, cupro-ammonium, if one chances to get a sniff at it, and how that inconvenience may be avoided by a little management. In addition to that memory, please now bear in mind that the intensity of the smell of odorous things is in proportion to the surface exposed. Presently, in order to use your cupro-ammonium fluid, some must be poured out into a vessel into which you can dip little pieces of paper. Now it is evident that the smell of a pint of cupro-ammonium, or of any other smelling fluid, will be less intense if the vessel be a comparatively narrow-mouthed jug than if it be a basin; but supposing a basin to be desirable for collateral reasons, then much smell may be avoided by providing yourself with a temporary cover, say a glass pane, which may be laid over the surface, resting on the basin rim at the intervals when the dipping of your pieces of paper must be interrupted.
Next as to the paper you are to use in making this bottle of artificial wood. The best for your purpose will be what is known as printing demy. Writing-paper, having a glazed surface, is not favourable. The glaze is produced by animal size, a material that does not go well with cupro-ammonium. It matters little, practically nothing at all, whether the printer’s demy be new or whether it be printed upon. I have made excellent artificial wood out of, I believe, all the London daily morning papers; so choose your paper, and let us fall to work. Theoretically and scientifically it matters not what shape you cut your paper into, but practically, and present purpose regarded, there can be no doubt but that discs of a circular shape, and scored with cuts all round the circumference, are most convenient. The discs may conveniently run about the accompanying size.
The basis or model of our bottle about to be, or rather flask, shall be a common oil-flask. Provide yourself, then, with one of these, and cleanse it thoroughly from all oil, the least touch of which would be fatal to the success of our workings. Having done this, provide some sort of stand, into which the neck of the flask being stuck, the whole may be turned round and round in the progress of working. It matters nothing what this movable stand is. A candlestick does very well, if you can find a candlestick with candle-socket big enough to admit the neck of the flask. A marmalade pot holding sand can always be got, and into the sand the mouth and neck of the flask being stuck, every necessary purpose will have been answered.
Preliminaries being thus seen to, you pour out some of the cupro-ammonium in, let us say, a basin. Do not be sparing as to the quantity you pour out, for a reason to be explained presently. Take now one of your paper circular discs, and, with your forceps nipping it quite at the edge, dip it into the cupro-ammonium bath. For how long? Ah! that is a question to be solved. Assuming your stock of cupro-ammonium to be in good working order—assuming it to have been brewing with the copper wire for not less than a month, air having been furnished to it day by day, as already enjoined—then about three seconds will be long enough for each immersion. Nothing but practice will settle the point, and after only a little practice the operator cannot be mistaken. Immerse, then, for trial a paper disc, and, withdrawing it after about three or four seconds, lay it upon the crown of your flask and spread it out regularly by means of your forceps and rubber-protected finger. If it feels slippery like an eel the fluid has come to condition; but otherwise, if the disc instead of feeling slippery give the impression of harshness, then the conditions are not all that one would desire them to be. The main question is this: will the next disc, when steeped in the bath, removed, and pressed down, stick satisfactorily to the preceding disc?
This we shall now see. I have shown you [here] how the discs must overlap each other like the scales of a fish. You need not be particular in aiming at the mathematical symmetry of the scale lying on a fish’s skin; it would be folly to attempt such a result except your discs had been mathematically cut to pattern, and extremely difficult of execution in any case. Supposing the adhesion to be satisfactory, you can go on covering the entire surface of the oil-flask, and I should think common sense would suggest that when you have come down a certain distance in your working it will be more convenient if you take the flask out of its support and reverse it on a tumbler thus:—
