1864.] ^g^ [Osborne. 



with it an even coating of the lithographic ink, hiding almost totally the 

 photographic delineation from view. The swimming, or as it is also more 

 properly called, " coagulation," is the next step ; it is accomplished by 

 letting the blackened print float upon the surface of boiling water, 

 with its uncoated side downwards. The chief result sought to be 

 secured by this operation is the coagulation of the albumen contained 

 in the film. This takes place, due to the action of the moisture and 

 heat together; and in addition to it another advantage is gained by 

 the percolation of the water through the paper, namely, the softening 

 and gelatinization of the gelatine contained in the coating of organic 

 matter under the ink. This change extends only to such portions of 

 the sensitive surface as were protected from the action of light by the 

 negative ; those which form the picture suffer no further alteration 

 while the print is swimming, due to the solvent action of water ; they 

 do not soften or swell, and demonstrate this fact by remaining de- 

 pressed, in relation to the other parts of the blackened surface, which 

 rise very perceptibly around them. 



After sufficient soaking, we have to remove from this print the 

 superfluous ink which is upon it, our object being to retain that por- 

 tion only which goes to form the picture. This is effected by placing 

 the wet sheet upon a smooth surface, and applying a moderate 

 amount of friction to it by means of a wet sponge, or similar sub- 

 stance. Gradually the ink leaves those portions of the blackened 

 print which represent the white parts of the original ; but the ex- 

 posed or positive portions retain it with great tenacity, owing to the 

 chemical alteration which the light has effected in them. Eventually 

 we find ourselves possessed of a copy of the original in lithographic 

 ink, which is washed in abundance of water, and dried. 



The ink upon the print, the preparation of which has been just 

 described, is transferred to stone by a process more or less thoroughly 

 understood by ordinary lithographers, occurring as it does not un- 

 frequently in the routine of their business. It consists in laying the 

 print, inverted, upon a clean and smooth lithographic stone, which has 

 been slightly warmed, and passing it through the press. The con- 

 sequence is, that the greasy lithographic ink passes over to the stone, 

 and forms there a chemical picture which is reversed, and from which, 

 after it has been properly "etched" or ''prepared," impressions can 

 be taken in the press. 



The coagulated albumen, upon which some stress has been laid, 

 plays an important part during this opei-ation of transferring ; for, 

 owing to its insoluble nature, no amount of washing can remove it 



