Dr. C. K. Akin on Calcescence. 37 



transmutation of Herschellic rays in the very act of emission. 

 By means of a couple of conjugate mirrors, having in one of the 

 foci an oxyhydrogen-flanie, and in the other a piece of lime, the 

 phenomenon of the transmutation of Herschellic into higher 

 rays, thus spontaneously occurring in the production of the 

 common lime-light, might be made to assume the ordinary form 

 of fluorescent phenomena. 



8. Conclusion. — In the original communication a third class 

 of experiments promising to effect a conversion of Herschellic 

 rays into Newtonic was adduced, which, from its being almost 

 entirely conjectural, shall be here passed over*. There were 

 also several distinctions mentioned, which most probably will 

 divide ordinary fluorescent phenomena from those to which atten- 

 tion has been directed in this paper. To distinguish these latter 

 phenomena from the former, the term Calcescence was suggested 

 to the author, from calcium, the name of the characteristic che- 

 mical constituent of lime, whose action on the oxyhydrogen-flame 

 suggested the preceding speculations and experimental attempts ; 

 and this term might be applied to all phenomena involving an 

 emission of Newtonic rays by the transmutation of incident Her- 

 schellic rays, or generally an emission of rays of increased refran- 

 gibility as compared with the generative incident. 



[9. Addenda. — (i) The experiments first tried in the summer of 

 1863, and briefly described in principle in the preceding pages, 

 were resumed with the aid of more efficient apparatus in the 

 spring of the present year. The mirror employed was one of 

 glass, quicksilvered on the back, of 3' aperture and 3^' focus. It 

 was supported at the sides by means of two screws passing 

 through two wooden uprights, properly connected to form a 

 stand. At its vertex, or highest point, a socket was fixed to the 

 mirror, in which a flat bar of iron, possessing the form of an 

 elongated S, was made to rest and held firm by binding screws. 

 The free end of this bar reached somewhat further from the 

 mirror than the principal focal distance, whilst its projection on 

 the plane of the mirror fell a little short of the centre of the 

 mirror. To this end of the bar, which was rounded and perfo- 

 rated, a brass ring or clip was attached, by means of a moveable 

 little brass rod held firm by a binding screw. The ring was placed 

 as nearly as possible concentrical with the mirror, and admitted 

 of a wooden tube, which, when placed so that its nearest end 

 was exactly at the distance of the principal focus from the mirror, 

 was held in its position by means of a screw and nut attached 

 to the brass ring or clip adverted to. At the end nearest to the 



* [The whole of the paper adverted to has appeared since in the Reports 

 of the British Association for 1863.J 



