192 METHODS OF MICROSCOPICAL EESEAECH. 



keep out lamp light or gas light from the adjoining 

 apartment (if any), will answer, provided there is 

 not a lamp within a few yards of the window, and 

 the moon is not shining brightly. The most 

 convenient light to work by is that afforded by a 

 paraffin lamp, protected by a chimney of ruby glass, 

 or a screen of good orange demy free from pin 

 holes. This screen must be so arranged as not to 

 allow a single ray of white light to enter the room 

 in any direction, while it allows a proper supply of 

 air to the lamp. If the operator wishes to work by 

 daylight he must either darken a room or large 

 cupboard entirely, and use the paraffin lamp as 

 before, or he may glaze the window with ruby 

 glass, and make it additionally secure by pasting a 

 layer of yellow demy over it, or two thicknesses 

 of bookbinders' red cloth may be used instead of 

 glass and paper. In whatever way the dark room 

 is lighted, the plate must be shaded from it as 

 much as possible, and only brought into the full 

 light for any length of time when development is 

 nearly complete, and it is necessary to use all safe 

 light to watch the completion of the process. The 

 unpacking and storing of plates, and placing them 

 in the dark slide, may be conducted in almost entire 

 darkness. Before commencing work the following 

 solutions should have been made up : l 



1 Since this article was originally written, photographic 

 chemistry has made great advances; the above developing 

 (&c.), solutions are here retained as good, but knowledge of 

 and experience in the art will enable the operator to make 

 choice of the modern formulae most suitable for his own 

 .method of working. 



