392 Intelligence and Miscellaneous Articles. 



preparation of the dye is substantially the same as that employed 

 by J. B. B. Wellington,* and is as follows. 



Fifteen grains of cyanine are gently heated (over a steam bath) 

 for from thirty to forty minutes in combination with 1 oz. of 

 chloral hydrate and 4 oz. of water. The whole mixture should 

 now be stirred vigorously. While this operation is going on, 120 

 grains of sulphate of quinine are dissolved by heat in a few ounces 

 of methylated spirit. (If methylated spirit cannot be obtained, a 

 solution of 90 per cent, alcohol and 10 per cent, wood spirits will 

 answer perfectly well.) One ounce of strong aqua ammonise is 

 now slowly added to the cyanine mixture above. Violent ebulli- 

 tion takes place immediately, chloroform being evolved, and cyanine 

 deposited in a soluble form on the sides of the vessel. The 

 mixture is allowed to settle for a few minutes, and then the 

 supernatant liquid is decanted off very slowly, care being taken 

 not to detach any of the cyanine that is formed on the sides. 



To the remaining cyanine, three or four ounces of methylated 

 spirit are added to dissolve it; the quinine solution is then 

 added ; and to the whole more methylated spirit, until the whole 

 mixture measures from eight to nine ounces. This solution 

 constitutes the " stock" solution, and should be kept away from all 

 light, as it is very apt to become decomposed. 



All of the above operations should be conducted in as little light 

 as possible. The following staining and drying processes should 

 be conducted in absolute darkness. 



To thirty ounces of water are added 1 \ drachms of the cyanine 

 stock solution ; the graduate that contained the cyanine is now 

 washed out, \\ drachms of strong aqua ammonise are added, and 

 the whole mixture is stirred vigorously. Into this bath two or 

 three plates, or half a dozen strips, can be dipped at once. They 

 should be left there about four minutes ; meanwhile the tray con- 

 taining the plates should be rocked continuously, so as to insure a 

 uniform action of the dye. 



This bath, after having been used once, should be thrown away, 

 as the action on a second batch of plates would be weak and 

 imperfect. The plates can now be drained, dried, and used. 

 While developing, I was careful to exclude all light whatever, al- 

 though I think it possible that the plates may be developed safely 

 in a dark greenish-yellow light. The developer used was a pyro- 

 and potash developer of (generally) normal strength. 



In the first experiments the spectrum was produced by a Bow- 

 land flat diffraction-grating, mounted on a spectrometer-circle. 

 This grating contained 17,000 lines to the inch. The observing- 

 telescope of the spectroscope was replaced by a camera and lens. 



Certain photographs were also taken by means of a Rowland 

 concave grating of 14,500 lines to the inch, and of 21 ft. 6 in. 

 radius of curvature. With this grating, the amount of light being 

 less and the dispersion greater than in the former cases, the ex- 

 posure had to be increased. 



In all of the experiments ruby-red glass screens were used in 

 * See Anthony Photographic Bulletin, December 24, 1887. 



