W. Crookes on the Wax-paper Photographic Process. 161 



description of the manipulation, as may render it more service- 

 able to those who have not hitherto paid attention to photo- 

 graphy in its practical details. This must be my excuse, if to 

 some I seem unnecessarily prolix. None but a practical photog- 

 rapher can appreciate upon what apparently trivial and unim- 

 portant points success in any branch of the art may depend. 



It may not be without service, if, before entering into the 

 practical details of the process, I say a few words respecting the 

 most advantageous way of arranging a photographic laboratory, 

 together with the apparatus, chemicals, &c, which are of most 

 frequent use. 



Among those requisites, which may be almost called absolute 

 necessaries, are gas, and a plentiful supply of good water, as soft 

 as can be procured. 



4. The windows and shutters of the room should be so con- 

 trived as to allow of their either being thrown wide open for pur- 

 poses of ventilation, or of being closed sufficiently well to exclude 

 every gleam of daylight; and the arrangement should admit of 

 the transition from one to the other being made with as little 

 trouble as possible, 



5. A piece of very deep orange-colored glass, about two feet 

 square, should be put in the window, and the shutter ought to 

 be constructed so as to allow of the room being perfectly dark- 

 ened, or illuminated, either by ordinary daylight, or daylight 

 which has been deprived of its photographic rays, by filtering 

 through the orange glass. The absorbing power of this glass 

 will be found to vary very considerably in different specimens, 

 and I know of no rule but experience to find out the quality of 

 any particular sample ; the best plan is to select from a good 

 stock one of as dark a color as possible. The proper color is 

 opaque to the rays of the solar spectrum above the fixed line E. 



6. The best source of heat is unquestionably gas. It will be 

 as well, however, to have a fire-place in the room, as, in some 

 cases, a gas stove will be inapplicable. There should be gas 

 burners in different parts of the room for illumination at night; 

 and also an arrangement for placing a screen of orange glass in 

 front of each. 



Several rough deal benches should be put up in different parts 

 of the room, with shelves, drawers, cupboards, &c. The arrange- 

 ment of these matters must of course depend upon the capabili- 

 ties of the room. 



7. The following apparatus is required. The quantities are 

 those that we have found necessary in this Observatory. 



Eight dishes. 



Eight mill board covers. 



Three brushes for cleaning dishes. 



A vessel for melting wax. 



SECOND SERIES, VOL. XXlt, NO. 65.—SEPT., !856. 



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