208 REPORT — 1859. 



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 arrangement of these matters 

 must of course depend upon the capabilities of the room. 



7. The following apparatus is required. The quantities are those that we 

 have found necessary in this Observatory: — 



Eight dishes. Six funnels. 



Eight mill-board covers. One funnel stand. 



Three brushes for cleaning dishes. Pint, half-pint, one ounce, and 

 A vessel for melting wax. one drachm measures. 



Two gauze burners. Three glass flasks. 



One box, iron. Boxes for holding paper. 



Filtering paper. Scales and weights. 



A still for water. Sponge, glass rods, stoppered 



One platinum, and three bone spa- bottles, &c. 



tulas (flat paper-knives). 



8. The dishes may be made of glass, porcelain, or gutta percha. Glass 

 and porcelain are certainly cleaner than gutta percha ; but for general use 

 the latter is far preferable, as with it there is no risk of breakage, and the 

 bottom of the dish can be made perfectly flat, which is a great advantage. 

 These dishes should be made of sufficient length to allow of a margin of 

 about half an inch at each end when the paper is in ; and the shape should 

 be made as nearly square as possible, by arranging them to take two or three 

 sheets side by side. 



The gutta percha should be of a good thickness, otherwise it will bend 

 and give way, if it be moved when full of liquid. The depth must depend 

 upon the size of the dish, and the purpose for which it is intended. The 

 dishes in use here accommodate three sheets of paper side by side ; they are 

 fifteen inches square, and one inch and a half deep. I think, however, for 

 some purposes, where they are not wanted to be moved about much (i. e. those 

 for holding the bath of hyposulphite of soda for fixing), the depth might be 

 advantageously increased to two inches and a half. Each dish ought to be 

 reserved for a particular solution, and should have a piece of millboard a 

 little larger than itself lor a cover. 



9. The brushes for cleaning the dishes are of two sorts ; a common scrub- 

 bing brush will be found the best for all parts but the corners, and for these 

 another kind must be used, having a handle about a foot long, at the end of 

 which are tufts of stiff bristles, projecting about three-quarters of an inch, 

 and radiating on all sides, forming a ball about two inches and a half in dia- 

 meter. Hardly any dirt will be found capable of resisting this brush if it be 

 pressed into a corner, and twisted round several times. The dishes ought 

 always to be put away clean, as the dirt is much more difficult to remove if 

 allowed to dry on. 



10. When a dish is to be cleaned, if it be of glass or porcelain, strong 

 nitric acid must be poured into it; if of gutta percha, it should be filled with 

 a strong solution of cyanide of potassium. After soaking for half an hour or 

 an hour, according to the state of the dish, the liquid is to be returned into 

 the bottle (both the nitric acid and the cyanide can be used several times), 

 the dish rinsed out with water, and then well scrubbed in every part with the 

 brushes ; afterwards it is to be washed several times in common water, once 

 with distilled water, and then placed in a slanting position against a wall, face 

 downwards, to drain on clean blotting-paper. 



