242 Intelligence and Miscellaneous Articles. 



normal of the face, to OT, and to the trace are respectively 



H cos sin yjr, H cos cos ijr, H sin 0. 

 Hence, using the theorem by resolving in these directions 

 and taking moments round OT, 



= 2 + H cos sin yfr = % ± H cos 8 cos yfr = t ± H sin 0, 



and 



0=2 + H{sin 2 -*|r tan x cos 2 + sin yfr sin 0(cos yjr + sin y(r tan % sin 0) } 



or 



= X + H sin ty (sin ^ tan ^ + sin cos ifr) . 



These reduce to equations (49) § 420 of Basset's ' Physical 

 Optics ' when the incident medium is isotropic. 



I may remark that I believe this theorem of Hamilton's 

 is nowhere referred to in the treatise just mentioned, nor in 

 Lord Rayleigh's article a Wave Theory/' in the Encyclopedia 

 Britannica, 9th ed., nor in Glazebrook's ' Report on Optical 

 Theories,' in the B.A. Reports, 1885. 



University of Tasmania, Hobart, 

 20th November, 1899. 



XIX. Intelligence and Miscellaneous Articles. 



CHEMICAL EFFECTS PRODUCED BY BECQUEREL's RAYS. 

 BY M. P. AND MME. CURIE. 



^HE rays emitted by very active radiferous salts of barium are 

 -*- capable of converting oxygen into ozone. When the radio- 

 active salt is kept in a stoppered bottle, a very distinct odour of 

 ozone is perceived on opening the bottle. M. Demarcay discovered 

 this phenomenon with some very active radiferous barium chloride 

 which we had sent him, for his spectroscopic researches, in a little 

 stoppered bottle- When the flask is opened the odour is incom- 

 pletely dissipated ; in order that it may regain its original strength 

 it is sufficient to close the flask some ten minutes. 



We have verified the production of ozone by starched potassium- 

 iodide paper, which becomes lightly tinted when placed before the 

 mouth of the bottle. The tint is deeper when the radiferous barium 

 chloride is brought in contact with the paper, whilst ordinary 

 barium chloride under the same conditions produces no effect. 



The radiferous compounds necessary for the production of ozone 

 are all very active and all luminous. The phenomenon seems more 

 nearly related to the radioactivity than to the luminosity. Thus a 

 very luminous carbonate of radium produces less ozone than a 

 chloride of radium less luminous but more strongly radioactive. 



We have likewise remarked a colouring action of Becquerel's 

 rays on glass. If a radium salt is kept for some time in a glass 

 flask, a violet coloration is perceived which appears to spread 

 itself from the interior of the flask towards the exterior. With a 



