" The chloroform or benzole solution, should be allowed to stand several days before being used, in order that the colouring matter, or any impurities in it, may be deposited. Filter through paper, that the solution may be sufficiently thin, shutting the top of the funnel to prevent too much evaporation, which would have the effect of thickening the solution. Benzole, of specific gravity much less than the chloroform, gives good results, but inferior to those ob tained by chloroform, which gives a solution almost colourless, and adheres firmly when the evaporation is completed; which also takes place more rapidly than with the benzole.
" The density of the solution of gutta-percha, which is always slightly coloured, retards considerably its complete clarification. It is necessary to avoid all impurities in this solution." The following is a method of transferring dry collodion negatives to paper, described by M. Bayard at a meeting of the French Photographic Society on Feb. 20th, 1857.
" Among the specimens which I have the honour to lay before you are some which have been obtained from very old negatives, and even from negatives which love been varnished. They have all been easily transferred. I cannot however promise you that it will always be so. It is probable that certain varnishes, and particularly fatty varnishes, may offer an impediment to the softening and removal of the collodion film.
" I am afraid also that albumen and gelatine spread upon the negatives may interfere with the success of the operation ; and I must warn you that I have not yet succeeded in transferring with certainty negatives produced by Taupenot's process, either simple or modified.
" The follovving is my process :— " In order to detach the ffim of collodion from the glass, I use paper coated with gelatine.
" To prepare it, dissolve in one litre of filtered rain water, 40 grammes (about 4 per cent.) of colourless gelatine. When the gelatine is dissolved, pour the solution into a dish which has been previously heated. Float the papers on the bath for one or two minutes, and hang them up by a corner to dry. When dry, keep them in a portfolio until required for use. The kind of paper which appe,ars most suitable for this operation is Canson's thin negative paper.
" If the negative to be transferred has just been taken, and is still wet, place the glass on a horizontal support, collodion side upwards, and cover it equally and evenly with water. Then, take
a sheet of the prepared paper, (which should be of the same size as the glass,) float the gelatinized side for three or four minutes on a bath of water, and having carefully removed it, lay it on the water with which the glass has been covered. Then, by inclining the glass, allow the water to drain off and the paper to become attached to the collodion. Place the glass perpendicularly, and allow it to dry spontaneously.
" When the negative which you wish to transfer ig old, and has not been varnished, immerse it for about a quarter of an hour, film upwards, in a dish full of water. Ten or twelve minutes after putting it into water, lay a sheet of gelatinized paper on the same water for three or four minutes. Then, remove the glass by the corners in such a way as to remove with it the paper which floats above, (the edges being of course properly adjusted to those of the glass). By proceeding cautiously the paper will adhere to the collodion. Drain and dry as before.
" When the negative has been varnished, proceed as before, with this difference, viz. :—add 3 or 4 per cent. of alcohol to the water, and let the glass remain in it half an hour.
" When the paper which has been glued to the collodion has become perfectly dry, (it should not be dried by the fire,) make an incision with the point of a penknife all round it, pretty close to the edges of the glass, and then immerse the negative in a dish filled to about an inch deep with water. A quarter of an hour after, you may endeavour to raise a corner of the negative film with the point of a knife. Should the film not come off with the paper, leave it immersed a little time longer. As soon as you find that the collodion will leave the glass, raise the paper carefully, without re moving the glass from the water, which always moistening the collodion renders the operation more easy. When the paper has been removed with the collodion film adhering to it, press it between blotting paper, and dry it.
" Negatives transferred in this way acquire great vigour for printing, and if the prints from them are found to be too strong in the contrasts, the negative should be waxed on the reverse side of the paper in the ordinary way." After M. Bayard had made the above communication, he, in order to spew with what ease these transfers could be made, placed in water a collodion negative on glass, having a sheet of gelatinized paper adhering to the film.