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VII. On the Discovery of the Metal Thallium. 

 By William Crookes, F.R.S. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 



MAY I request you to give me an opportunity of replying to 

 certain accusations receotly made against me by M f 

 Lamy in reference to this subject ? 



Chemists are doubtless aware that my title to the discovery of 

 the metallic nature of thallium has been disputed by M. Lamy, 

 and that he has been supported iu this position by eminent 

 scientific men in France. It has been stated, both in M. Dumas* 

 report to the Aeademie des Sciences*, and even more pointedly 

 in M. Lamy's recent memoir f, that I first obtained a knowledge 

 of the metallic nature of thallium from M. Lamy, and that I 

 appropriated that knowledge as my own. I should gladly have 

 abstained from any controversy as to the mere question of priority 

 in the discovery or publication of this fact, and am well content 

 with the recognition of my claims which has been accorded to 

 me by English chemists ; but the purport of the above state- 

 ments is of such a nature that it becomes necessary for me, both 

 from regard for my own credit and from respect to those who 

 have acknowledged my title to the original discovery of thallium 

 and of its metallic nature, to show that the accusations above 

 referred to are unfounded. 



Your readers may remember that I published in this Journal, 

 in April 1861, a paper " On the Existence of a new Element, 

 probably of the Sulphur Group," and in May following, " Farther 

 Remarks on the supposed New Metalloid" J. From that time 

 my attention was almost exclusively directed to the further elu- 

 cidation of the chemical history of the new element ; and about 

 the middle of April 1862 it was arranged that I should exhibit 

 some specimens of thallium and its compounds in the Interna- 

 tional Exhibition §. My intention was to have exhibited a large 

 series of specimens ; but as I had not been able to meet with 



* Comptes Rendus, vol. lv. p. 866, Dec. 15, 1862. 



f Annates de Chimie et de Physique, 3 ser. vol. lxvii. April 1863. 



% Chemical News, May 18, 186 i, vol. iii. p. 303. 



§ " Exhibition Building, South Kensington, W., 



April 17, 1862. 

 " My dear Sir, — I shall be greatly pleased to see a specimen of thal- 

 lium in the Exhibition. Will you kindly call on me on Saturday the 19th 

 inst. between 6| a.m. and 7 p.m., and I will arrange the matter with you. 



" In great haste, 



"Yours, very trulv. 

 " W. Crookes, Esq." "C, W. Quin." 



