[249] 



ON SOME BLOWPIPE.REACTIONS. 



BY E. J. CHAPMAN, Ph. D., 



Professor in University College, Toronto. 



I.— ON THE REACTIONS OF METALLIC THALLIUM BEFORE THE 



BLOWPIPE. 



The following reactions are given from direct experiments by the 

 writer : * 



In the closed tube, thallium melts easily, and a brownish-red 

 vitreous slag, which becomes pale-yellow on cooling, forms around the 

 fused globule. 



In the open tube, fusipn also takes place on the first application of 

 the flame, whilst the glass becomes strongly attacked by the formation 

 of a vitreous slag, as in the closed tube. Only a small amount of 

 sublimate is produced. This is of a grayish-white colour, but under 

 the magnifying-glass it shews in places a faint ridescenee. 



On charcoal, per se, thallium melts very easily, and volatilizes in 

 dense fumes of a white colour, streaked with brown, whflst it imparts 

 at the same time a vivid emerald-green coloration to the poiut and 

 edge of the flame. If the heat be discontinued, the fused globule con- 

 tinues to give off copious fumes, but this action ceases, at once, if the 

 globule be removed from the charcoal. A deposit, partly white and 

 partly dark-brown, of oxide and teroxide is formed on the support; 

 but, compared with the copious fumes evolved from the metal, this 

 deposit is by no means abundant, as it volatilizes at once where it 

 comes in contact with the glo\ving charcoal. If touched by either 

 flame, it is dissipated, immediately, in impartiag a brilliant green 

 colour to the flame-border. The brown deposit is not readily seen on 



* The reactions given ty Ckookes arc as follows : — " The metal melts instantly on charcoal, 

 and evolves copious hrown fumes. If the bead is heated to redness, it glows for some time after 

 "the source of heat is removed, continually evolving vapours which appear to be a mixture of 

 metal and oxide. A reddish amorphous sublimate of proto-peroxide surrounds the fused 

 globule. When thallium is heated in an open glass tube, it melts and becomes rapidly con- 

 verted into the more fusible protoxide, which strongly attacks the glass. This oxide is of a 

 dark red colour when hot, solidifying to a bro\vn crystalline mass. The fused oxide attacks 

 glass and porcelain, removing the silica. Anhydrous Peroxide of Thallium is a brown powder, 

 fusing with difficulty and evolving oxygen at a red heat, becoming reduced to the protoxide. 

 The phosphate and sulphate will stand a red heat without change." 



