CH. VIII] PREPARATION OF LANTERN SLIDES 215 



3. Cardboard at 45 degrees, lighted by a 40 watt mazda lamp 

 above the cardboard 30 seconds. 



4. Cardboard at 45 degrees with a 16 candle-power frosted bulb 

 above the cardboard 120 seconds. 



For contact printing with the same negative, 30 cm. (12 in.) from 

 the light, if artificial, the following times sufficed: Diffused day- 

 light, 2 sec.; Mazda, 40 watt lamp, i sec.; Frosted bulb, 16 c.p. 

 lamp, 10 sec.; Petroleum lamp, 10 sec.; Gas mantle, 5 sec. 



332. Rapid preparation of lantern slides. It occasionally 

 happens that one needs a lantern slide at very short notice. In 

 such a case, the negative can be taken and fixed in the hypo, 

 rinsed in water, and put into the camera and a lantern slide 

 exposed ( 329). Then the negative can be washed as usual. 

 The lantern slide is then developed and fixed, and washed a few 

 minutes in water. It is then placed a few moments in 95% alcohol 

 or denatured alcohol for dehydration. After removal from the 

 alcohol it is dried in a draught or in the current of an electric fan. 

 Negatives can be quickly dried in the same way. One can then 

 make contact prints. 



333. Type written lantern slides. It frequently happens that 

 one desires to project some statement or some table. This can be 

 written as stated above ( 316, 321), or the statement or table 

 can be made neatly with a typewriter, using a black ribbon. 

 Then this can be used just as any other printed matter and a 

 photographic lantern slide made from it. 



If in a great hurry one can use the negative form of lantern slide 

 and dry quickly ( 332). This will give white letters on a black 

 ground ( 329a). (For film slides see 333a). 



333a. Film lantern slides. There has been recently introduced by the 

 Eastman Kodak Co., a method of producing lantern slides on celluloid 

 films, comparable to film negatives. The celluloid film is quite thick. There 

 must be a negative as for glass lantern slides. The film is used in place of a 

 lantern-slide plate. The printing is like printing cyco, velox or other paper. 

 When the lantern-slide film is dry, after being developed and washed like a film 

 negative, it is varnished and placed between two pieces of paper with the 

 proper opening for the picture. 



Naturally, these film slides are very light and are not fragile. Unfortunately 

 the substance of which the film is composed is inflammable, and therefore the 



