14 



SETTING THE PICTURE. 



When the picture is sufficiently developed, it may either be set 

 at once, or carefully laid aside until a convenient opportunity 

 occurs. To set Daguerreotype pictures, they must be washed in a 

 suitable vessel, (a preserve pot large enough to contain the plate 

 will answer the purpose,) first in very pure water, and then in a 

 solution of hyposulphite of soda, about fifty grains to the ounce of 

 water, which must be carefully strained, and to which may be added 

 a small quantity of alcohol. The sensitive coating will soon be 

 removed, and the plate should again be washed in pure water, 

 agitating it perpendicularly, until the water runs off in a continuous 

 stream. 



FIXING THE IMAGE. 



The plate being taken from the water, which should never be 

 allowed to dry off, is placed upon a wire stand , adapted to preserve 

 it in a perfectly horizontal position. The gold solution, which may 

 be purchased of the opticians and chemists, or prepared according 

 to the formula given in the Appendix, is poured on the plate, 

 until it is entirely covered, and the flame of a large spirit lamp 

 applied to the under surface, in such a way that every part may be 

 equally heated. In a few moments, the picture will become very 

 clear and bright, when the lamp must be withdrawn, and the plate 

 removed quickly, and again plunged into cold water. The plate is 

 now finally washed, by pouring pure water at a boiling heat over it, 

 holding it as perpendicularly as possible. When the plate is quite 

 clean, it may be dried by blowing gently downwards, and when 

 neatly managed, it will be quite free from spots. The plate may be 

 supported on a stand, as in the washing apparatus, Fig. 12, page 8, 

 or held at the corner with a pair of pliars. The gold solution 

 must be rejected if it should have changed colour, or deposited any 

 precipitate. 



The following new mode of fixing and strengthening pictures by 

 oxidation, has been proposed by Mr. Charles G. Page, M. D., 

 Professor of Chemistry, Columbia College, Washington : 



The impression being obtained upon a highly polished plate, and 

 made to receive, by galvanic agency, a very slight deposit of copper 

 from the cupreous cyanide of potassa, (the deposit of copper being 

 just enough to change the colour of the plate in the slightest degree,) 

 is washed very carefully with distilled water, and then heated over 

 a spirit lamp, 'until the light parts assume a pearly transparent 



