The Chemical Gazette 321, 1.3.1856
By J. W. Slater.
Chemists who use the ordinary fube-colorimeter in analytical operations often find some difficulty in comparing two coloured solutions. Even though the tubes may be exactly of the same calibre, yet the eye is annoyed by the refraction of light in passing through a body with curvilinear surface. The following simple arrangement, which displays the liquids between two plane surfaces, will, I think, give perfect satisfaction. From a stout glass tube, about 1% inch in diameter, a number of portions or hoops are cut about two-thirds of an inch in width. All these are carefully ground smooth at one edge, and then cemented down upon a strip of clear plate glass. When the cement is perfectly hard, the upper edges of the glass rings are ground upon apolishing wheel so that they form a series of cells exactly equal in depth. All that is requisite, in using this colorimeter, is to fill the cells with the respective solutions to be compared, and place the apparatus upon a sheet of white paper, or, covering the whole with another slip of plate glass, equal in size to the one upon which the rings are cemented, to hold up the entire apparatus to the light. The upper plate fitting closely upon the ground edges of the rings, prevents the solutions from escaping. In this manner shades of colour may be distinguished, which, if en: closed in tubes, might be confounded even by the most practised observer.
- Northern Analytical College, Sheffield, Dec. 24, 1855.
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