ELEMENTARY PHOTO-MICROGRAPHY. 59 



raise it. A mask with an opening of a suitable size 

 and shape placed between the negative and the 

 paper will give a neat finish to the print. 



Bromide paper is the quickest for microscopic 

 work, and can be done by gaslight. It gives a 

 contrast of velvety black and white, but the picture 

 is not visible after exposure until developed. More 

 uniform results may be obtained from artificial light 

 than from daylight, if several prints are to be taken 

 from one negative, because the correct exposure, 

 having once been ascertained, can be repeated. 



The Velox carbon matt is especially suitable for 

 the purpose, being a slow paper capable of develop- 

 ment without a dark room lamp and in fairly full 

 gaslight. This is a great relief to the eyes, avoid- 

 ing, as.it does, the fatigue caused by frequent alter- 

 nations of bright light for exposure and comparative 

 darkness for development, when quick papers are 

 used. In any case, all the negatives to be printed 

 from should be put in separate frames and the ex- 

 posure made before lowering the light. When held 

 flat in the hand, bromide paper will curl slightly 

 with the sensitised surface inside. Wetting the 

 corners with the thumb and finger in order to dis- 

 tinguish the different sides is not a clean habit. 

 The exposure depends on the negative, but for 

 average density the Velox carbon takes twenty 

 seconds at six inches from a No. 5 burner. A thin 

 negative should be held further away from the 

 light ; a dense one, nearer. The frame is best kept 

 between the eyes and the gas to shade the eyes 



