We take a piece of this paper of the proper size, and lay it on the varnished or pictured side of the negative, which is itself laid in a wooden frame, like a picture-frame.  Then we place a thick piece of cloth on the paper.  Then we lay a hinged wooden back on the cloth, and by means of two brass springs press all close together,—­the wooden back against the cloth, the cloth against the paper, the paper against the negative.  We turn the frame over and see that the plain side of the glass negative is clean.  And now we step out upon the roof of the house into the bright sunshine, and lay the frame, with the glass uppermost, in the full blaze of light.  For a very little while we can see the paper darkening through the negative, but presently it clouds so much that its further changes cannot be recognized.  When we think it has darkened nearly enough, we turn it over, open a part of the hinged back, turn down first a portion of the thick cloth, and then enough of the paper to see something of the forming picture.  If not printed dark enough as yet, we turn back to their places successively the picture, the cloth, the opened part of the frame, and lay it again in the sun.  It is just like cooking:  the sun is the fire, and the picture is the cake; when it is browned exactly to the right point, we take it off the fire.  A photograph-printer will have fifty or more pictures printing at once, and he keeps going up and down the line, opening the frames to look and see how they are getting on.  As fast as they are done, he turns them over, back to the sun, and the cooking process stops at once.

The pictures which have just been printed in the sunshine are of a peculiar purple tint, and still sensitive to the light, which will first “flatten them out,” and finally darken the whole paper, if they are exposed to it before the series of processes which “fixes” and “tones” them.  They are kept shady, therefore, until a batch is ready to go down to the toning room.

When they reach that part of the establishment, the first thing that is done with them is to throw them face down upon the surface of a salt bath.  Their purple changes at once to a dull red.  They are then washed in clean water for a few minutes, and after that laid, face up, in a solution of chloride of gold with a salt of soda.  Here they must lie for some minutes at least; for the change, which we can watch by the scanty daylight admitted, goes on slowly.  Gradually they turn to a darker shade; the reddish tint becomes lilac, purple, brown, of somewhat different tints in different cases.  When the process seems to have gone far enough, the picture is thrown into a bath containing hyposulphite of soda, which dissolves the superfluous, unstable compounds, and rapidly clears up the lighter portions of the picture.  On being removed from this, it is thoroughly washed, dried, and mounted, by pasting it with starch or dextrine to a card of the proper size.

The reader who has followed the details of the process may like to know what are the common difficulties the beginner meets with.