1822.] Dr, Clarke on Cadmium. 12a 



unbounded power which iron exercises over the domain of 

 metaUic salts would itself be a discoverij. The cause of the effect 

 is the only legitimate subject of question. As to the phaenomena" 

 of the bars immersed in phosphorous acid (B. M. seems to have 

 used phosphoric acid), I have simply stated the fact as it occurred 

 to me, and became the object of my senses ; and the same obser- 

 vation apphes to the platinum wires. This last was witnessed 

 by several persons as well as myself, though it is neither for nor 

 against the general issue ; neither do I mean to insist upon this 

 phenomenon, which may have been the incidental effect of an 

 impurity in the solution of nitrate of silvei" ; but that the pheno- 

 menon did occur as I have described it, I do most unequivocally 

 assert. 



I have nothing to do with the mere hypothetical part of 

 B. M.'s paper; I must, however, stigmatize the expression 

 '^ fallacious " (which he, however, with one exception only, has 

 proved experimentally correct), and ^^ inferences unwarranted 

 by facts,'' to be precipitate, rude, and ungentlemanly. 

 I have the honour to be (in haste), Sir, 



Your obedient servant, 



J. Murray. 



Article XI. 



On Cadmium, and the Habitudes of some of its Ores, showing the 

 Means of detecting the Presence of the Metal in English Ores 

 of Zinc. By E. D. Clarke, LL.D. Professor of Mineralogy in 

 the University of Cambridge, &c. 



(To the Editor of the Annals of Fhilosophy.) 



DEAR SIR, Cambridge, Jan. 21, 1822. 



It is now nearly two years since I communicated to the 

 Editor of the Annals of Philosophy a discovery (since fully con- 

 firmed by much abler chemists than myseli) of the presence of. 

 Cadmium in the Derbyshire ores of zinc.^ As I believe that the 

 complete reduction of this metal and its exhibition in the metaUic 

 state have not yet been accomplished by any chemist in Great 

 Britain (all the specimens of it that have been seen, coming to 

 us from the continent), I shall again call the attention of your 

 chemical readers towards the means we possess of effecting 

 this object, especially as I have since discovered cadmium in a 

 greater variety of substances than I was at first aware of, and 

 have it in my power thereby greatly to facilitate the means of 

 procuring it. In one single instance, and almost accidentally, I 



* See Annals of Philosophy, xv. 272, Art. V. dated Feb. 18, 1820. 



