234 Royal Society: — Messrs. Lockyer and Roberts 



end of the volume ; on pp. 52, 53 there are certainly five misprinta n 

 as well as one or two other points that apparently need alteration^.. 

 M. de Bruno in many places gives notices of the history of they 

 subject; and this renders a mistake in the very first page of/' 

 the Preface matter for regret. The passage runs as follows : — \ 

 " La Theorie des Invariants .... doit son origine a un excellent 

 memoire de Boole sur les Transformations lineaires insere dans le 

 Cambridge and Dublin Mathematical Journal, 1847." The article 

 in question consists of two parts, both in the third volume of the 

 4 Cambridge Mathematical Journal ;' and the first part was pub- 

 lished in November 1841. The ' Cambridge and Dublin Journal ' 

 was a second series of the Cambridge Journal. There were four 

 volumes of the latter published. The twofold mistake in the date 

 and the name of the Journal has the effect of quite misrepresenting 

 the history of the origin of the subject, though it can only be due 

 to an oversight, as the means of correcting it are to be found 

 within the volume itself. 



XXX. Proceedings of Learned Societies, 



ROYAL SOCIETY. 



[Continued from p. 159.] 



March 11, 1875. — Joseph Dalton Hooker, C.B., President, in 

 the Chair. 



T^HE following paper was read : — 



" On the Absorption-Spectra of Metals volatilized by the 

 Oxyhydrogen Elaine." By J. Norman Lockyer, F.R.S., and W. 

 Chandler Koberts, Chemist of the Mint. 



The researches which have recently been published on the ab- 

 sorption-spectra of various metals, first by Roscoe and Schuster 

 and subsequently by one of us *, establish beyond all question the 

 facts that — 



I. In addition to the well-known line-spectra, channelled-space 

 spectra are produced by the vapours of certain metals ; and, 



II. Such spectra are produced by vapours which are competent 

 to give at other times, not only line-spectra, but continuous spectra 

 in the blue, or blue and red. 



As the temperature employed for the volatilization of the metals 

 in the experiments to which we have referred did not exceed bright 

 redness, or that at which cast iron readily melts, the range of metals 

 examined was necessarily limited. We have therefore considered it 

 desirable to extend these observations to the less fusible metals, 

 as well as to ascertain whether the spectra of those which were 

 volatilized at the lower temperature would be modified by the ap- 

 plication of a greater degree of heat. For this purpose we have em- 

 ployed the flame of an oxyhydrogen blowpipe. This instrument 



* Proc. Koy. Soc. vol. xxii. pp. 362 and 371 respectively. 



