On a new Photo-Lithographic Process. 179 



meeting of the Loudon Photographic Society, January 4th, 

 1859 (see Photographic Journal, Jan. 8th., 1859). 



4th. In consequence of his manner of wetting the whole 

 gelatinous surface before applying the ink, he increases the 

 difficulty of getting the ink to adhere to the altered parts of 

 the coating ; by smearing them with semi-dissolved gelatine, 

 he deteriorates the quality of the ink which does adhere, 

 and the idtimate result will be rotten lines.* 



Mr. W. G. Newton has taken a patent for photo-litho- 

 graphy, a detailed copy of which is given in the Photographic 

 Journal for Nov. 22nd, 1858; this gentleman prepares his 

 stone or zinc plate in a manner very similar to M. Poitevin ; 

 he exposes in the camera, or under a positive, and the result 

 is that he has to use the altered insoluble parts of the gela- 

 tinous surface, not as points of attraction for the ink, but as 

 a means of protecting the stone while he removes and inks 

 in the unaltered portions ; this method obliges him, 1st, if 

 he wants to get the best results, to expose in the camera, if 

 not to use a positive on paper, or a real positive on albu- 

 menized glass, all three methods of exposing having many 

 disadvantages. 2nd. Inasmuch as he uses for the boundary 

 of his lines that section of the gelatinous surface which is in 

 contact with the stone, not that on which the picture is im- 

 pressed by the luminous rays, he can never obtain the 

 sharpest definition. 



With these objections I believe his process to be sound in 

 theory, and by it he may produce good results as far as land- 

 scapes and portraits are concerned, but not so when the copy 

 of a map, or any other design composed of and bounded by 

 hard dense lines, is required. 



M. Jobart, in a communication to the Academy of Sciences 

 of Paris, has intimated his discovery of a photo-lithographic 

 process, based upon principles differing totally from the fore- 

 going, namely, some peculiar action exerted by iodide of 

 silver upon gum arabic. The only notice of his invention 

 I have been able to procure, is in the Athenceum for Feb., 

 1859, where the description of it is too indistinct and sketchy 

 to admit of any criticism. 



Since the above was written I have met with the following statement 

 in the Illustrated London News, Jan. 22nd, 1859, p. 33 :— 



* * Certain patents taken out in Dec. 1855, by M. Poitevin, for photo- 

 lithographic and carbon printing (Nos. 2815 and 281G), have just lapsed, 

 the renewal fees not having been paid on them." J. W. 0. 



