LANTERN SLIDES 235 



There are many toning processes involving the use of 

 copper, vanadium, gold, and other solutions, and these 

 are very useful when brown, green, blue, or other coloured 

 images are required. Formulae for these and for special 

 developing methods can be found in the almanac of the 

 British Journal of Photography, or cartons of the salts, 

 such as the Leto toners, may be bought for the purpose. 



In many cases colouring gives a very good effect, and 

 the process is very simple when the transparent Japanese 

 colours or aniline dyes are used. The colour is applied in 

 thin washes, and gives a most realistic result without 

 calling for any great degree of artistic ability. 



When finished, perfectly dry, and preferably varnished, 

 the slides are suitably masked and bound up in contact 

 with a piece of plain glass. Binding strips with a very 

 strong adhesive must be used, and we have found the 

 " Specialist " spot-binders very good : a strip with the 

 spots on is placed along the top edge of the slide with the 

 spots to the front, and serves as a guide to the lanternist 

 when placing the slides in the lantern. 



The Dark-Room Lamp. The illumination of the dark- 

 room calls for some attention on account of the almost 

 universal use of colour-sensitive plates. The colour of 

 the light used must be selected according to the sensitive- 

 ness of the emulsion to the various parts of the spectrum, 

 and it should be made to give the greatest amount of 

 light that can be used without fogging the sensitive 

 materials. In the best lamps the light is not projected 

 direct from the radiant through the light filter or safe- 

 light, but reflected from the back, while the radiant is 

 screened from the front. By this means a brighter 

 illumination can be used with safety, and there is no risk 

 of damaging the safelight. The simple enlarging ap- 

 paratus shown at Fig. 70 forms a most excellent lamp 

 of this type if the necessary safelight is placed in the 

 front, the camera being removed. 



