16 



paper is then carefully and completely dried. It is then dipped 

 into a solution of nitrate of silver, and dried without artificial heat 

 in a perfectly dark room. This paper is very sensitive when quite 

 new, but gradually loses its impressionability. 



5. BROMIDE PAPER. Dissolve 100 grains bromide potassium in 

 one ounce distilled water, and soak the paper in this solution. 

 Take off the superfluous moisture, and when nearly dry, brush it 

 over on one side only with a solution of 100 grains nitrate of silver, 

 to one ounce water. This paper is readily prepared, and tolerably 

 sensitive. If required to be very sensitive, it should be brushed 

 over a second time with the nitrate of silver. 



These papers really vary very little from each other, and we 

 should recommend Nos. 1, 2, and 5. The same general rules must 

 be observed in the preparation of each. They must all be dried in 

 the dark after the nitrate of silver has been used. If the paper is 

 brushed over, the brush must be large and broad, so that the whole 

 of the sheet may be wetted in two or three sweeps, otherwise marks 

 will appear in the paper corresponding to the lines made by the 

 brush. If blotting paper is required, it must be frequently 

 changed, and never used for two different preparations. 



A sheet of either of the above papers may be taken and laid 

 with the marked side upward, on a piece of board covered with 

 flannel : on this paper must be laid the negative picture, with its 

 face downwards, and over both a piece of plate glass, the glass and 

 board being tightly pressed together by screws or weights. The 

 frame described, page 7, is a most convenient apparatus for this 

 purpose. It must now be exposed to light ; in about ten or fifteen 

 minutes of bright sunshine, or in several hours of common daylight, 

 a beautiful positive picture is produced, in which the lights and 

 shadows are corrected. These pictures have a fine effect, though 

 they lose somewhat of their sharpness in passing through the copy. 

 They may be set with hyposulphate of soda, as directed for the 

 negative pictures. If the negatives are clear, and the shadows 

 dark, a great many copies may be obtained from them. 



We may mention here, that copies of PRINTS, FEATHERS, LACE, 

 etc., are obtained in the same manner as the positive pictures just 

 described ; and where it is necessary to reverse them afterwards, 

 as in the case of prints, the process must be gone through twice ; 

 that is, a strong negative picture must be first obtained, and then 



