26S II L. ~\Y heeler — Doxible Halides of Tellurium 



3TeCl 4 . It will be shown beyond that the formula of the 

 potassium compound at least must have been obtained from 

 analyses of impure products. Yon Haner* analyzed the 

 double bromide of tellurium and potassium, and concluded 

 that the salt had the composition represented by the formula 

 2KBr. TeBr 4 . 3H 2 0. I have reinvestigated this salt and 

 found it to contain two molecules of water and not three. 

 Probably Von Hauer analyzed the salt without previously 

 having dried it sufficiently or without having taken precau- 

 tions to remove included water which the crystals always con- 

 tain. He dehydrated this salt and used it in his work on 

 the atomic weight of tellurium. 



More recently Willsf determined the atomic weight of 

 tellurium by means of the same salt. He does not give any 

 analyses of the hydrous compound, but states that the salt 

 contains water and gives directions for dehydrating it. Ram- 

 raelsberg in his " Handbuch der krystallographisch-physi- 

 kalischen Chemie" (p. 289) quotes the formula of the dehy- 

 drated compound from Wills' work and assigns to this 

 Baker's^: measurements, which do not belong to it, but to the 

 hydrated compound with the three supposed molecules of 

 water of crystallization. The present investigation has shown 

 that the anhydrous salt is isometric, the hydrous one being 

 orthorhombic. 



Ramsay§ says that "By mixing aqueous solutions of the 

 constituent halides, tellurium halides combine thus : TeCl 4 

 2KC1, TeBr 4 2KBr, TeI 4 2KI. These compounds' form reddish 

 crystals. Few attempts have been made to prepare double 

 halides." Although a thorough search of the literature on 

 this subject has been made, in connection with the present 

 work, no analyses of the double chloride or iodide could be 

 found. Berzelius's work as regards their preparation and 

 Rammelsberg's attempt to determine the formula of the 

 chloride comprise all the work that has been done on these 

 two salts. It must be concluded that the formulae given by 

 Ramsay were deduced by analogy with the double bromide, 

 especially since his statements in regard to color, method of 

 preparation and composition only apply, in all respects, to the 

 double bromide. 



It will be seen from the above summary that very little 

 satisfactory work has been done on this class of compounds, 

 and, therefore, the present investigation has been undertaken 

 with the view of making a thorough study of the double 



* Journ. prakt Chem., Ixxiii, 98. 



f Jour. Chem. Soc, xxxv, 711. 



i Jour. Cheui. Soc , xxxv, 711. 



§ System of Inorganic Chemistry, edition of 1891, p. 168. 



