There is evidently a growing taste for photographic portraits on such articles as watches, gold or silver cigarette cases, match boxes, etc., and the jewellers who undertake to get this class of work done usually charge a pretty good figure for it.

As the carbon method of producing pictures of this kind may be of service to many of our readers, we shall assume at once that the reader is already quite familiar with the practical working of that process, for we here say that anyone who takes up the working of this process for the first time and attempts to apply it to the present purpose, must not expect to meet with any great success in his first few essays. It goes without saying, that it is the double transfer system that must be employed - the picture being developed on a temporary support, and then transferred to the article desired. It will at once be seen by practical workers that the ordinary commercial flexible sup-port is not suitable for the reason that it is too thick and unyielding to be pressed into sufficiently close contact on a convex surface, such as the dome of a watch-case, for example, to obtain a perfectly finished transfer. It may, however, sometimes be successfully used for quite cylindrical articles.

For the above reasons it will be obvious that a more flexible and yielding support must be employed. One is the India rubber support as first used by Swan ; another is a film of collodion. We will deal with the for mer first. Some thin " foreign post" paper, the thin-ner the better, so long as it will withstand the warm water in the development, is coated with a solution of India rubber about the consistency of thin treacle. The best way of obtaining this is to get a tin of solution from the rubber stores and thin it down with benzole to the required consistency. It is poured into a dish and the paper floated upon it and then hung up for the benzole to evaporate. The paper had best be coated a few days before it is required for use, so as to ensure that all the solvents of the rubber have thoroughly evaporated.

This India rubber support is used in precisely the same way as the ordinary flexible support, the exposed tissue is squegeed upon it, developed, and then allowed to dry. The picture need not be alumed; indeed, it will be better for our present purpose if it is not. The picture is now ready for transferring to whatever maybe required, which for the moment, we will assume to be the dome of the watch-case. It is unnecessary to mention that it must be removed from the watch; this a neighboring watchmaker will do for one. The dome is then cleaned with benzole, to remove all traces of grease or dirt. It is then coated on the outer side with a solution of gelatine containing a little chrome alum, such as that used for double transfer paper. The following is a good formula to employ:

Nelson's No. 1 gelatine 1/2 oz.

Water 10 oz.

Chrome alum dissolved in 1 oz. of water 6 gr.

The dome is evenly coated with this and allowed to dry. To make the transfer neatly, trim the print to the required size and put it and the watch dome in cold water for ten minutes or so. Next, put the latter in warm water at about 105° to 120° Fahr., until it just feels slimy. Then take the print, having previously marked it as a guide to position, and put it into contact with the dome, of course avoiding air bubbles, and remove the two and press in close contact with a soft dry handkerchief, gently rubbing towards the edges with the fingers so as to remove all superfluous water. It is then allowed to become thoroughly dry spontaneously. When dry the back of the paper is moistened with benzole, and after resting for a minute or two the paper can be slipped off, leaving the picture firmly attached to the metal. It now only remains to varnish the work. This may be practically a cold lacquer, and when dry is hard and durable as is the lacquer on our lenses. It is simply flowed over and drained off, and it dries in a few hours.

We mentioned just now that collodion might be used as a temporary support, and perhaps on the whole it is the best to employ. Here is the method: A glass plate, after being waxed, or prepared with French chalk, is coated with ordinary enamel collodion, thickened with two or three grains per ounce of pyroxiline, so that it yields a thick film. After the collodion has thoroughly set, the plate is put into a dish of water to soak, and is afterwards washed under the tap to get rid of the solvents of the collodion. The exposed tissue is then squeegeed on that, developed in the ordinary manner and allowed to dry. When dry the film can be stripped off and trimmed and then mounted on the metal, as just described. It is a good plan to trim the picture while it is still on the glass - a wheel trimmer and zinc shape is convenient for the purpose. The collodion film has an advantage over the rubber support, inasmuch as it is transparent, so that air bubbles can be seen and the picture better arranged in position. After the transfer the cellodion can be dissolved off with a mixture of ether and alcohol.

In conclusion, it may be mentioned that for carbon pictures on metal a tissue should be selected that contains a large proportion of pigment to gelatine, and should also be printed from a tolerably thin negative, so as to avoid a high relief in the image, which is objectionable in this class of picture, and, moreover, it serves to indicate the method by which it has been produced, which, in some instances, it is not desirable to do. - "British Journal. "