398 Intelligence cmd Miscellaneous Articles. 



charcoal. If touched by either flame, it is dissipated immediately, 

 imparting a brilliant green colour to the name-border. The 

 brown deposit is not readily seen on charcoal; but if the metal be 

 fused on a cupel, or ou a piece of thiu porcelain or other non-redu- 

 cing- body, the evolved fumes are almost wholly of a brownish 

 colour, and the deposit is in great part brownish black. It would 

 appear, therefore, to cousist of T10 3 rather than of a mixture of 

 metal and oxide. On the cupel thallium is readily oxidized and 

 absorbed. It might be employed, consequently, as suggested by 

 Crookes, in place of lead, in cupellation ; but to effect the absorp- 

 tion of copper or nickel, a comparatively large quantity is required. 

 When fused on porcelain, the surface of the support is strongly 

 attacked by the formation of a silicate, which is deep red whilst 

 hot and pale yellow on cooling. 



The teroxide, as stated by Crookes, evolves oxygen when heated, 

 and becomes converted into TIO. The latter compound is at once 

 reduced on charcoal, and the reduced metal is rapidly volatilized 

 with brilliant green coloration of the flame. The chloride produces 

 the same reaction, by which the green flame of thallium may easily 

 be distinguished from the green copper-flame, the latter, in the 

 case of cupreous chlorides, becoming changed to azure blue. With 

 borax and phosphor-salt, thallium oxides form colourless glasses, 

 which become grey and opaque when exposed for a short time to a 

 reducing-flame. With carbonate of soda they dissolve to some 

 extent ; but on charcoal a malleable metallic globule is obtained. 

 The presence of soda, unless in great excess, does not destroy the 

 green coloration of the flame. 



Thallium alloys more or less readily with most other metals before 

 the blowpipe. With platinum, gold, bismuth, and antimony re- 

 spectively, it forms a dark grey brittle globule. Yv r ith silver, cop- 

 per, or lead, the button is malleable. With tin, thallium unites 

 readily ; but the fused mass immediately begins to oxidize, throw- 

 ing out excrescences of a dark colour, and continuing in a state of 

 ignition until the oxidation is complete. In this as in other reac- 

 tions, therefore, the metal much resembles lead. 



ON THE PHYSICAL PROPERTIES OF GALLIUM. 

 BY LEGOQ DE BOISBAUDRAN. 



I have recently prepared rather more than half a gramme of pure 

 gallium. In the liquid state this metal. is of a beautiful silvery 

 whiteness ; but in crystallizing it assumes a very pronounced bluish 

 tinge, and its lustre notably diminishes. 



By suitably working the solidification of overmelted gallium, iso- 

 lated crystals are obtained : these are based octahedra, which I am 

 occupied in measuring. 



In a first trial (April 1876) the melting-point had been found to 

 lie between 29° and 30°, or about 29°*5. I have just examined six 

 specimens of gallium electrolyzed successively from one and the same 

 solution. The foreign metals supposed to be present would be un- 

 equally distributed among the different fractions collected. 



