[ *5 6 1 [Book .VI, 



C H- A P, XXVIII. 



OF THE *JEWLY DISCOVERED SEMI-METALS. 



Sylvanite. Menacbinite. Uranite. and Titanite. 



BEFORE the account of femi-metals is concluded, 

 it is proper briefly to notice four femi-metallic 

 fubftances which have lately fallen under the obfer- 

 vation of mineralogifts, but which have not yet under- 

 gone a complete examination. 



A new femi metal has been difcovered by Facebay, 

 to which Mr. Kirwan gives the name of SYLVANITE^ 

 from its being found in Tranfilvania. Its colour is 

 grey inclining to red, its fracture broad or granularly 

 foliated, with -a flight degree of malleability. Its 

 weight is about fix times that of water. When heated 

 it melts as eafily as lead, gives a thick white, fmoke, and 

 at laft a brownifh flame. In cooling it fhews ioms 

 difpofition to cryftallize. By continued heat it en- 

 tirely evaporates. It eafily amalgamates with mer- 

 'cury by fimple trituration. . It combines with fulphur, 

 and forms with it a ftrjated mafs like crude antimony. 



Sylvanite is foluble in concentrated vitriolic acid, 

 and the folution in a moderate degree of heat is crim- 

 fon red, but by the addition of water or heat it is pre- 

 cipitated. It may alfo be difTolved in a fmall propor- 

 tion in nitrous acid, and the folution until it heats is 

 greenifh. The beft folvent is aqua regia, with which 

 a yellow folution is produced. Its calx is of an acid 

 nature and unites with alkalis ; it is alfo foluble in. 

 acids. This fingular fubftance was at firft taken for 

 regulus of antimony, and afterwards for fulphurated 

 bifmuth. 



A fubftancp 



