469 



Group III. Gases whose cooling power is greater : — 

 olefiant gas, ammonia, vapours of alcohol and ether. 

 Group IV. Hydrogen. 



Dr, Apjohn next drew the attention of the Academy to 

 a metallic ore recently found at the Kilbricken Lead 

 Mine, County of Clare, which he had received through a 

 friend from Mr. M. Taylor, the gentleman who conducts the 

 mining operations in that district. It occurs in amorphous 

 masses of a bluish grey colour; has a metallic lustre, and 

 something between a compact earthy and close foliated struc- 

 ture. Specific gravity =6-407 ; hardness intermediate be- 

 tween that of galena and sulphuret of antimony. Subjected 

 to the action of the blowpipe sulphur is burned off; white 

 oxide of antimony is deposited upon the charcoal ; and a 

 metallic globule is produced, brittle at first, but which be- 

 comes malleable lead after having been submitted for some 

 time to the action of the oxidating flame. In muriatic acid 

 the ore dissolves, though slowly, with the evolution of sul- 

 phuretted hydrogen ; and the solution, when poured into a 

 large quantity of boiling water, gives a white precipitate 

 (oxichloride of antimony.) When this precipitate has sub- 

 sided, the solution is found to contain nothing but chloride 

 of lead, with traces of antimony and iron. From these ex- 

 periments the mineral was concluded to be a combination of 

 sulphur, lead, and antimony; and to determine the proportions 

 in which they were associated, the following analytic process 

 was adopted. 



44-52 grains of the ore, previously reduced to a fine 

 powder, were introduced into a ball, blown upon a tube of 

 Bohemian glass ; and through this a current of dry chlorine 

 was made to pass, the arrangement of the apparatus being 

 such, that by a rectangular bend in the portion of the tube 

 beyond the ball, the chlorine was made to bubble through a 



