Fixing The Image So That The Light Can No Longer Act On It

Two or three porcelain or glass dishes, in form, something like fig. 24.

A plate support, fig. 25. Few, I believe, now make use of this, although it is a very convenient article.

Hyposulphite of Soda,

A pair of Plyers.

In Europe, they also use a drying apparatus, Fig. 27, but this, like the plate support,

is a matter of little consequence, and may be dispensed with. I will, however, describe it, for the benefit of those who may wish to use it.

A vessel made of copper or brass, tinned inside, and large enough to take in the largest plate, but not more than half an inch wide, is the most convenient. It must be kept perfectly clean. Hot distilled water is poured into it, and the temperature kept up by a spirit lamp.

Hyposulphite of Soda.--Having made a solution of hyposulphite of soda, and well filtered it--the strength is immaterial; about half an ounce of the salt to a pint of distilled water is sufficient--pour it into one of the porcelain dishes, put into another plain, and into a third distilled water. Immerse the plate with its face downwards into the hyposulphite, and the whole of the sensitive is removed, and the light has no farther action upon it; it is then to be removed from the hyposulphite and plunged into the plain water, or placed upon the support, fig. 25, and the water poured over it. It is then washed in a similar manner with the distilled water and well examined, to see that not the slightest particle of dust rests on the suface. The next step is to dry it.

This may be readily accomplished by holding the plate with your plyers, and pouring distilled water over it--if it is hot, so much the better. Apply the spirit lamp to the back, at the corner held by the plyers, at the same time facilitating the operation with the breath; pass the lamp gradually downwards, finishing at the extreme corner. The last drop may now be removed by a little bibulous paper. A single drop, even, of distilled water allowed to dry on any part of the surface, is certain to leave a stain which no after process can remove.

To illustrate the necessity for having perfectly clean water, and free from all foreign matter--only to be avoided by using that which is distilled-- in these processes, I will relate a little anecdote.

An operator in this city (New York) frequently made complaint to me, that his plates were occasionally very bad; coming out all over in little black and white spots and spoiling many very good pictures, regretting at the same time that perfect plates were not made, for he had lost many customers in consequence of these defects. These complaints being somewhat periodical, I suggested that the fault might be in the hyposulphite, or chloride of gold solutions, or particles of dust floating about in the room, and not in the plate.

A few days after he stated, that his plates having served him again in the same way, he procured a fresh supply of hyposulphite of soda and chloride of gold, but after applying them the result was no better. He then, by my advice, thoroughly cleaned his wash dishes, bottles and water pail, made fresh solutions and had no further trouble, becoming satisfied that the plates suffered an undue share of censure.