10
NEGATIVE PHOTOGRAPHS.
pins, (the common tinned ones will answer, but, if the expense is not aconsideration, those made of silver wire will do better,) and a glass rodor two.
The materials necessary to produce all the varieties of sensitivepaper which will be brought under consideration in this section are—
I. Nitrate of Silver . The crystallized salt should, if possible,always be procured. The fused nitrate, which is sold in cylindricalsticks, is more liable to contamination, and the paper in which eachstick of two drachms is wrapped being weighed with the silver, rendersit less economical. A preparation is sometimes sold for nitrate ofsilver, at from sixpence to niuepence tlio ounco less than the ordinaryprice, which may induce the unwary to purchaso it. This reductionof price is effected by fusing with the salt of silver a proportion of somecupreous salt, generally the nitrate. This fraud is readily detected byobserving if the salt becomes moist on exposure to the air. A verysmall admixture of copper renders the nitrato of silver deliquescent.The evils to the photographer are, want of sensibility to light, and theperishability (even in the dark) of the finished drawing.
2. Muriate of Soda, (Common Salt .)
3. -- of Baryta.
4. - of Strontia.
5. - of Ammonia.
0. - of Peroxide of Iron.
7. - of Lime.
8. Chlorate of Potash.
9. Chloride of Soda, (Labarraque ’s disinfecting Soda Liquid.)
10. Hydrochloric Acid , (Spirits of Salts .)
II. Solution of Chlorine in water.
12. Phosphate of Soda.
13. Hydrochloric Ether.
15. Tartrate of Potash and Soda, (Rochelle Salts.)
16. Iodide of Potassium , (Ilydriodato of Potash .)
17. Bromide of Potassium , (Ilydrobromatc of Potash .)
18. Diacetate of Lead, (Sugar of Lead.)
19. Spirits of Wine.
21. Distilled Water , or Boiled Rain Water.
Many other chemical preparations, and some of the elementarybodies, will be often mentioned in connection with many processes towhich the white papers are applied, but it is not thought essontial toenumerate them in this place.
a. Nitrated Paper.
The most simple kind of photographic paper which is prepared, isthat washed with the nitrate of silver only; and for many purposes itanswers remarkably well, particularly for copying lace or feathers, and it