NATURAL PHILOSOPHY. 163 



APPLICATION OF PHOTOGRAPHY TO WOOD ENGRAVINGS. 



Mr. Robert Hunt, in a communication to the London Art Journal, January 

 18o9, on the above subject, says : " It should be understood, that there is not 

 the slightest difficulty in producing very perfect photographic pictures upon 

 boxwood blocks. Even by applying the nitrate or chloride of silver to the 

 surface of the wood, very satisfactory photographs could be obtained ; but 

 the difficulty in this case is, that the silver salt gives a brittleness to the 

 wood, and it is liable to " chip off " under the tool; hence it is not possible 

 to produce the fine lines. By coating the wood Avith albumen, however, 

 this has been avoided ; but the wood-engraver complains of the presence of 

 the film of albumen preventing him from working with his usual facility. 

 This objection is, in time, almost entirely overcome by the use of collodion, 

 the attenuated film offering scarcely any obstruction to the engraver's tool. 

 All that is necessary is, to adopt one of the so-called dry collodion processes, 

 and to obtain from a good negative on glass a positive copy on the block. 

 It is important that the processes should be simplified as much as possible, 

 to avoid all risk of injuring the wood. It is well to coat every part of the 

 wood, except the face, with a thin layer of a transparent Tarnish, so that the 

 iodized collodion may be applied, and the face dipped into the solution of 

 nitrate of silver, without the risk of having any absorption. Again ; in the 

 slight fixing process which is necessary, no very high degree of permanence 

 being required, this varnish also protects the wood. By employing a some- 

 what sluggish collodion process, very charming pictures may be easily 

 obtained and rendered sufficiently permanent. 



Now arises the wood-engraver's difficulties. He has been trained to cut 

 along certain well-defined lines, and he does not understand working upon a 

 drawing in which there are none of those lines. It is, however, merely a 

 question of education; the conventional system must be abandoned, and the 

 engraver taught to use some judgment in the execution of his work. 



Crookes's Process for applying Photography to Wood Engraving. The fol- 

 lowing plan, devised by Mr. Crookes, of London, for placing photographs 

 on wood for the used of wood-engravers, seems to obviate most of the diffi- 

 culties heretofore experienced. Thin films of albumen, of dry collodion, of 

 collodion transferred from the glass upon a bituminous varnish, of a coat- 

 ing of gelatine and allum, followed by a solution of hydrochlorate of am- 

 monia, etc., have formed the bases of the different methods proposed in this 

 country and in Europe; but in all, or nearly all, it has been found necessary 

 to subject the wood block to a fixing bath, to the certain injury of its sur- 

 face. The method proposed by Mr. Crookes seems liable to no such objec- 

 tion. The block is to be covered by candle-light, or in a darkened room, 

 " with a mixture composed of oxalate of silver and water, to which may be 

 added a little gum or pulverized Bath brick, to suit the convenience of the 

 engraver." The preparation is spread by the finger, precisely as the drafts- 

 man now spreads his solution of flake white, before making his drawing on 

 the block. It is then put in a dark place to dry, and as soon as dry is ready 

 to receive the picture, which is obtained by the ordinary process of photo- 

 graphic printing. " The block requires no subsequent washing, nor any 

 preparation of any description, before being placed in the hands of the 

 engraver," who then proceeds with his engraving in the usual way. But he 

 is warned that ho " must not expose the block to the direct action of the 



