550 Chronicles of Science. [Oct., 



extends sixty feet or more beneath the furnace and its chambers, 

 is carried forward with constant agitation, by means of a submerged 

 rotating helix, and at length falls into a well at the extremity, from 

 which it is withdrawn, freed from oxyd of copper, but generally 

 containing a small residuum of unoxydized sulphid, which, if of 

 sufficient importance, is separated by a repetition of the process 

 with the Water Furnace, or by a rapid calcination in a reverberatory, 

 of the mass impregnated with chlorids, by which means the residual 

 copper left by imperfect burning becomes readily soluble in the 

 sulphurous chlorid bath of the water- tank. 



"It will be seen that for sulphuretted ores containing gold, the 

 treatment in the fire-tower, with the aid of a bath of water only, 

 affords a simple mode of desulphurization, and leaves the gold 

 particles in a state most favourable for amalgamation, while in the 

 case of auriferous ores containing copper, a similar result may be 

 obtained and the copper which is lost in the ordinary method of 

 working such ores, recovered by means of the chlorid bath. 



" It is claimed by the designers of this series of processes that 

 copper can in this way be produced, at about one-third the cost of 

 the ordinary method. The small consumption of fuel and the 

 mechanical facilities afforded for handling great masses of material, 

 are such that the new method will probably be found especially 

 advantageous, in the treatment of low-grade ores, in regions where 

 transportation is difficult and fuel scarce. The patentees have a 

 small experimental furnace, eighteen feet high, at East Boston, 

 but are now erecting at the Harvey Hill Mine, near Quebec, a 

 furnace thirty feet high, which it is expected will enable them to 

 treat fifty tons of seven per cent, ore in twenty-four hours." 



9. PHYSICS. 



Light. — In a paper "On the Estimation of Star-colours," Sidney 

 B. Kincaid, Esq., has described a metro-chrome, or apparatus for 

 measuring colour. It consists essentially of three parts : — 1, a 

 lantern for the production of a constant light ; 2, a contrivance for 

 imparting to that light the necessary colour, and so arranged that 

 the proper tinge once produced, a record of it can be obtained, so as 

 to enable it to be reproduced at any time ; 3, an apparatus to throw 

 that coloured light into the field of the telescope as an artificial star, 

 which can thus be viewed side by side with the image of the real 

 one. The source of light is a very fine platinum wire, rendered 

 incandescent by a current of electricity transmitted through it from 

 a Smee's battery of two cells. The platinum wire is brought into 

 the focus of a lens, so that the rays of light from the lantern issue 



