528 Mr. "W. Gr. Lettsom on Rhdbdophane, a new Mineral. 



of the substance ; but as lie informs me he has no leisure to 

 go into the matter at present, I am not as yet able to state to 

 the Society what is the precise constitution of the mineral. 



Within a few days after showing the original specimen to 

 Mr. Maskelyne, I had the pleasure of learning from him that 

 he had been enabled, I believe by means of the spectroscope, 

 to recognize two other specimens of the mineral in the old 

 collection at Oxford, where they are simply labelled " Blende 

 from Cornwall" *. 



On my showing Mr. Ludlam the specimen I had received 

 from him, he informed me that it came from " the Turner 

 Collection," which is now in his possession — and that it is 

 described in the third volume of M. Levy's Catalogue of that 

 Collection, under the heading of " Zinc sulfurS J$o. 75. 

 Mamelonne, bmn, fibreux dans la cassure, ressemblant au 

 plomb-gomme, avec plomb phosphate, CornciiaHles." I should 

 not say the specimen resembles plomb-gomme much ; neither 

 have I observed any phosphate of lead upon it. 



There were two specimens of the mineral in the Turner 

 Collection as well as in the collection at Oxford, the locality 

 attributed to them all being simply "Cornwall;" and as M. 

 Levy's Catalogue was published in 1837 (that is to say, more 

 than forty years ago), I fear there is but little hope of ascer- 

 taining at what mine they were raised : even, however, if 

 that were made out, it seems improbable the workings there 

 should be still carried on. 



Neither in the collection at the British Museum, free access 

 to which has been kindly granted to me, nor in that at King's 

 College, nor in the old collection belonging to Mr. Vicary at 

 Exeter, nor in that of the late Sir John Aubyn at Devonport 

 have I been able to find a specimen of the mineral in question. 



The name Rhabdophane, which this species has received, was 

 selected as one indicating the stripes or bands which it exhi- 

 bits in the spectroscope. 



For the information of such of our chemists as may feel 

 disposed to work upon British blendes for gallium, I here 

 subjoin the results that were obtained by M. Lecoq de Bois- 

 baudran in operating upon some of those specimens that I for- 

 warded to him. The quantity of material used for the exami- 

 nation was, T believe, in every case 20 grammes. 



No. 1. Redruth . . Poor enough. 

 No. 2. Cumberland. . Rich enough. 



* There is a small specimen without label in the Brooke Collection at 

 Cambridge. 



