330 Mr. Cundell on the practice of the Calotype Process. 



comes dry, which they will do if sufficiently impressed in the 

 camera. If the paper be allowed to dry before washing off 

 the gallo-nitrate, the lights sink and become opaque; and if 

 exposed in the dry state to heat, the paper will embrown; the 

 drying therefore ought to be retarded, by wetting the back of 

 the paper, or the picture may be brought out by the vapour 

 from hot water*. The fifth and last process is 



27. The Fixing of the Picture, — Which is accomplished by 

 removing the sensitive matter from the paper. The picture, 

 or as many of them as there may be, is to be soaked in warm 

 water, but not warmer than may be borne by the finger; this 

 water is to be changed once or twice, and the pictures are then 

 to be well-drained) and either dried altogether or pressed in 

 clean and dry blotting-paper, to prepare them to imbibe a so- 

 lution of the hyposulphite of soda, which may be made by 

 dissolving an ounce of that salt in a quart (forty ounces) of 

 waterf. Having poured a little of the solution into a flat dish, 

 the pictures are to be introduced into it one by one; daylight 

 will not now injure them; let them soak for two or three 

 minutes, or even longer if strongly printed, turning and mo- 

 ving them occasionally. The remaining unreduced salts of 

 silver are thus thoroughly dissolved, and may now, with 

 the hyposulphite, be entirely removed, by soaking in water 

 and pressing in clean white blotting-paper, alternately; but 

 if time can be allowed, soaking in water alone will have the 

 effect in twelve or twenty-four hours, according to the thick- 

 ness of the paper. It is essential to the success of the fixing 

 process, that the paper be in the first place thoroughly pene- 

 trated by the hyposulphite, and the sensitive matter dissolved ; 

 and next, that the hyposulphite compounds be effectually re- 

 moved. Unless these salts are completely removed, they induce a 

 destructive change upon the picture, they become opaque in the 

 tissue of the paper, and entirely unfit it for the next, which is 



28. The Printing Process, — The picture being thus fixed, 

 it has merely to be dried and smoothed, when it will undergo 

 no further change. It is however a negative picture (§ 4), and 

 if it have cost some trouble to produce it, that trouble ought 

 not to be grudged, considering that you are now possessed of 

 a matrix which is capable of yielding a vast number of beau- 

 tiful impressions. I have had as many as fifty printed from 

 one, and I have no doubt that as many more might be ob- 

 tained from it. 



29. The manner of obtaining these impressions has been so 



* I now find that a horizontal jet of steam answers better than anything 

 I have yet tried. 



f Specific gravity 1014. 



