172 MICRO-SPECTROSCOPE AND POLARISCOPE [ CH. VI 



mine, although the ammonium sulphide would not enable one to 

 make the distinction. Furthermore it is unsafe to compare objects 

 dissolved in different media. Different objects as " cyanine and 

 aniline blue dissolved in alcohol give a very similar spectrum, but 

 in water a totally different one." "Totally different bodies show 

 absorption bands in exactly the same position (solid nitrate of ura- 

 nium and permanganate of potash in the blue)." (MacMunn). 

 The rule given by MacMunn is a good one : " The recognition of 

 a body becomes more certain if its spectrum consists of several 

 absorption bands, but even the coincidence of these bands with 

 those of another body is not sufficient to enable us to infer chemical 

 identity ; what enables us to do so with certainty is the fact : that 

 the two solutions give bands of equal intensities in the same parts oj the 

 spectrum which undergo analogous changes on the addition of the same 

 reagent. ' ' 



REFERENCES TO THE MICRO-SPECTROSCOPE AND 

 SPECTRUM ANALYSIS 



The micro-spectroscope is playing an ever-increasingly important role in 

 the spectrum analysis of animal and vegetable pigments, and of colored 

 mineral and chemical substances, theiefore a somewhat extended reference to 

 literature is given. Full titles of the books and periodicals will be found in 

 the Bibliography at the end. 



Angstrom, Recherches sur le spectre solaire, etc. Also various papers in 

 periodicals. See Royal Soc's Cat'l Scientific Papers; Anthony & Brackett ; 

 Beale, p. 269 ; Behrens, p. 139 ; Kossel und Schiefferdecker, p. 63 ; Carpenter, 

 p. 323 ; Browning, How to Work with the Spectroscope, and in Monthly Micr. 

 Jour., II, p. 65 ; Daniell, Principles of Physics. The general principles of 

 spectrum analysis are especially well stated in this work, pp. 435-455 ; Davis, 

 p. 342; Dippel, p. 277 ; Frey ; Gamgee, p. 91 ; Halliburton ; Hogg, p, 122 ; 

 also in Monthly Micr. Jour., Vol. II, on colors of flowers; Jour. Roy. Micr. 

 Soc. , 1880, 1883, and in various other vols. ; Kraus; Lockyer; M'Kendrick; 

 MacMunn; and also in Philos, Trans. R. S., 1886; various vols. of Jour Physiol.; 

 Nageli uiid Schwendener; Proctor; Ref. Hand-Book Med. Science, Vol. I, p. 

 577, VI. p. 516, VII, p. 426; Roscoe; Schellen; Sorby, in Beale, p. 269; also 

 Proc. R. S., 1874, p. 31, 1867, p. 433; see also in the Scientific Review, Vol. 

 V, p. 66, Vol. II, p. 419 ; Landauer, Spectrum Analysis. The larger works on 

 Physiology, Chemistry and Physics may also be consulted with profit. 



Vogel, Spectrum analysis; also in Nature, Vol. xix, p. 495, on absorption 

 spectra. The bibliography in MacMunn is excellent and extended. 



For hemochromogen in medico-legal cases see Bleile, Trans. Aruer. Micr. 

 Soc., 1900, p. 9. 



