480 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



ferred to a gelatin film to prevent inversion of the prints. 

 The invisible image thus formed is developed by pouring 

 upon the plate petroleum, to which one fifth or one sixth its 

 volume of benzol has been added, and keeping the plate in 

 motion and renewing the solvent until the picture appears in 

 the color of the varnish and the lights exhibit the clear metal. 

 The plate is then washed under a stream of water to check 

 the further action of the solvent, and allowed to drj^ in the 

 light, when the varnish hardens, and acquires the power of re- 

 sisting the acid employed in etching. The latter process is 

 conducted as usual with dilute nitric acid until deep enough 

 to allow the use of the plate with an ordinary printing-press. 

 IZ C^ January I ^QQ. 



NEW PHOTOLITHOGKAPHIC OE AUBELTYPE PROCESS. 



It is said that an entirely new and very superior process 

 for multiplying impressions from photographic negatives me- 

 chanically has been invented by Aubel, of Cologne, and has 

 been named after him, in order to emphasize its entire inde- 

 pendence of all previous processes for a like purpose. If it 

 prove to be all that is claimed for it, it will doubtless in- 

 crease the applications of photolithography. The use of or- 

 ganic substances, as gelatin and asphaltum, is altogether 

 discarded, and no transferring agent is necessary, the photo- 

 graphic negative being so changed that it permits a transfer 

 to be made to stone at any time in the simplest, cheapest, 

 and most direct manner, with the preservation of all its ex- 

 cellences, while the subsequent lithographic manipulations 

 remain as usual. Ordinary lithographic inks are used in 

 printing, and the operation is much easier than with the usual 

 transfers, since there is no difficulty in keeping open the 

 finest as well as the heaviest hachuring. The stone can also 

 be completely washed with turpentine without injuring the 

 drawing, or affecting the finest tints in the subsequent print- 

 ing. Among the most decided advantages of the process 

 may be mentioned: 1st, the absence of all necessity for ex- 

 cessive nicety in its details, so that success in the prepara- 

 tion of plates is a rule, want of it the exception ; 2d, the 

 freedom from spreading or alteration of the lines of the orig- 

 inal ; 3d, the possibility of completing the preparation and 

 transfer of a plate to stone in from half an hour to two hours ; 



