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 collodion, was removed directly from the nitrate-of-silver bath to the camera, so as to be exposed to its image while still wet. It is obvious that this process is one that can hardly be performed conveniently at a distance from the artist's place of work. Solutions of nitrate of silver are not carried about and decanted into baths and back again into bottles without tracking their path on persons and things. The _photophobia_ of the "sensitized" plate, of course, requires a dark apartment of some kind: commonly a folding tent is made to answer the purpose in photographic excursions. It becomes, therefore, a serious matter to transport all that is required to make a negative according to the method described. It has consequently been a great desideratum to find some way of preparing a sensitive plate which could be dried and laid away, retaining its sensitive quality for days or weeks until wanted. The artist would then have to take with him nothing but his camera and his dry sensitive plates. After exposing these in the camera, they would be kept in dark boxes until he was ready to develop them at leisure on returning to his _atelier_. Many "dry methods" have been contrived, of which the _tannin process_ is in most favor. The plate, after being "sensitized" and washed, is plunged in a bath containing ten grains of tannin to an ounce of water. It is then dried, and may be kept for a long time without losing its sensitive quality. It is placed dry in the camera, and developed by wetting it and then pouring over it a mixture of pyrogallic acid and the solution of nitrate of silver. Amateurs find this the best way for taking scenery, and produce admirable pictures by it, as we shall mention by-and-by. * * * * *