1865.] Dr. Beale on a New Object-glass. 35 



10. Magnesium wire, presented suitably to the focii/, burns with its 

 intensely luminous flame. 



In all these cases the effect was due, in part, to chemical action ; this, 

 however, may be excluded. 



1 1 . A plate of any refractory metal, sufficiently thin, and with its reflec- 

 tive power suitably diminished, is raised to incandescence in the dark focus. 

 Gold, silver, copper, aluminium, and platinum have been thus rendered 

 incandescent. 



12. Platinized platinum shows the effect best : in a thin leaf it may be 

 rendered white-hot, and on it is depicted an incandescent image of the coal- 

 points. When the points are drawn apart, or caused to approach each 

 other, their incandescent images conform to their motion. 



The assemblage of phenomena here described, and others to be referred 

 to in my completed memoirs, may, I think, be properly expressed by the 

 term Calorescence. This word involves no hypothesis, and it harmonizes 

 well with the term fluorescence, now universally employed with reference 

 to the more refrangible end of the spectrum*. 



III. " Note on a New Object-glass for the Microscope, of higher 

 magnifying power than any one hitherto made." By LIONEL S. 

 BEALE, M.B., F.R.S., F.R.C.P., Professor of Physiology and of 

 General and Morbid Anatomy in King's College, and Physician 

 to King's College Hospital. Received December 30, 1866. 



I desire to record the completion of a new objective, with a magnifying 

 power double that of the twenty-fifth. This glass is a fiftieth, and magnifies 

 nearly three thousand diameters with the low eyepiece. Messrs. Powell 

 and Lealand, the makers, to whom science is indebted for this the highest 

 power yet made, produced a sixteenth in the year 1840, and the twenty- 

 sixth in 1860. 



The fiftieth defines even better than the twenty-fifth, which is now 

 made instead of the twenty-sixth. Plenty of light for illuminating the 

 objects to be examined is obtained by the use of a condenser provided 

 with a thin cap, having an opening not more than the -Jjjth of an inch in 

 diameter. The preparation may be covered with the thinnest glass made 



* On the 5th of last December I tried the passage of the rays from the electric lamp 

 through a great number of differently coloured glasses. Incandescence was obtained 

 through ahnost all of them ; and in one instance, the radiation passing through a blue 

 glass, the thermograph of the coal-points was of a pink colour. A thick black glass, 

 obtained from Mr. Ladd, when held in front of the lamp, was found to be not perfectly 

 opaque ; still the platinum could not be raised to incandescence a tall when placed in 

 the focus. Being called away from the Eoyal Institution early in the afternoon, I gave 

 directions to my assistant, Mr. Barrett, to continue the experiments. He informs me 

 that on placing in the path of the rays a combination -of two thin plates of black glass, 

 one transmitting a whitish -green, and the other a deep red, the light was entirely inter- 

 cepted, and feeble though distinct incandescence was obtained at the focus. With ra- 

 diation through the solution of iodine, the thermograph on thigday rose to a white hoat. 



D2 



