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XXXIII. Notices respecting Neiv Books, 



Photographed Spectra. One Hundred and Tliirty-sicc Photographs of 

 Metallic, Gaseous, and other Spectra, printed by the Permanent 

 Autotype Process. By J. B,akd Capbcm, F.B.A.S. London: E. and 

 E. Spon. 



r PHE work before us is a handsome octavo volume, consisting of 

 -*■ 37 plates of permanent photographs and 80 pages descriptive 

 of the plates. There are about 85 photographs of metallic spectra, 

 and 50 of spectra of gases. 



The metallic spectra extend mostly from H to a little beyond E, 

 the red end of the spectra of course not being recorded by the pho- 

 tographic process. They were obtained with a direct-vision spec- 

 troscope with one compound prism of 5 prisms, and are thus spectra 

 of small dispersion, the interval E to G- occupying about 1| inch in 

 the photographs. The author remarks that his results "are not 

 intended to be placed by the side of photographs of spectra of 

 larger dispersion taken for comparison of the metals, study of the 

 solar spectrum, &c. ; but they may perhaps prove useful to amateurs 

 and others working with spectroscopes of small dispersion, for 

 comparison of spectra in their general aspect, and for study of the 

 points and peculiarities attaching to most spectra which are gene- 

 rally brought out in our prints." 



The spectra of the metals were partly obtained from the spark 

 between points of the metal, and partly from ignition of pieces of 

 the metal in the electric arc given by 40 pint Grove's cells. 



The former series includes Arsenic, Aluminium, Antimony, Bis- 

 muth, Barium, Calcium, Cadmium, Copper, Indium, Iron, Lead, 

 Magnesium, Mercury, Nickel, Palladium, Selenium, Silver, Stron- 

 tium, Tellurium, Thallium, Titanium, Tin, Zinc, Zirconium. The 

 spectra obtained from the voltaic arc (the more interesting series) 

 are those of Aluminium, Antimony, Bismuth, Beryllium, Boron, 

 Cadmium, Chromium, Cobalt, Copper, Didymium, Erbium, Gold, 

 Indium, Iridium, Iron, Lead, Magnesium, Manganese, Molybde- 

 num, Nickel, Niobium, Palladium, Platinum, Rhodium, Ruthenium, 

 Silver, Thallium, Titanium, Tin, Tungsten, Uranium, Vanadium, 

 Yttrium, Zinc, Zirconium. 



Mr. Capron has earned the thanks of spectroscopists for the 

 large amount of useful work which he has performed for them, in 

 the way of preliminary investigation. No exact scale or measure- 

 ments accompany the photographs ; and they will be chiefly useful 

 in indicating by comparison with each other the lines which belong 

 to particular metals, and the conditions under which particular lines 

 are produced. In the investigation of the spectrum of any sub- 

 stance, it is a great saving of time to begin with small dispersion, 

 and afterwards to apply higher powers when it becomes an object 

 to determine exactly the wave-length of particular lines. 



But although no exact measurements are given, and although the 

 photographs vary very perceptibly in length, nearly all show lines 



Phil Mag. 8. 5. Vol. 5. No. 30. March 1878. Q 



