washed her face since the five-seconds picture was taken. No. 4 was
exposed sixty seconds, that is to say, three or four times too long. It
has a curious resemblance to No. 1, but is less dusky. The contrasts of
light and shade which gave life to No. 3 have disappeared, and the face
looks as if a second application of soap would improve it. A few trials of
this kind will teach the eye to recognize the appearances of under- and
over-exposure, so that, if the first negative proves to have been too long
or too short a time in the camera, the proper period of exposure for the
next may be pretty easily determined.

The printing from the negative is less difficult, because we can examine
the picture as often as we choose; but it may be well to undertime and
overtime some pictures, for the sake of a lesson like that taught by the
series of pictures from the four negatives.

The only other point likely to prove difficult is the toning in the gold
bath. As the picture can be watched, however, a very little practice will
enable us to recognize the shade which indicates that this part of the
process is finished.

* * * * *

We have copied a picture, but we can take a portrait from Nature just as
easily, except for a little more trouble in adjusting the position and
managing the light. So easy is it to reproduce the faces that we love to
look upon; so simple is that marvellous work by which we preserve the
first smile of infancy and the last look of age: the most precious gift
Art ever bestowed upon love and friendship!

It will be observed that the glass plate, covered with its film of