234 Scientific Intelligence, Sfc. 



XI. — New method of reducing Litharge, emploged at Freiberg. 



M. Harle describes this method as follows : — the furnace is made 

 to pass from a cupellation furnace into a small furnace, filled with 

 charcoal, where combustion is kept up by a natural draught. The 

 reduced lead runs into a vessel, adapted for its reception, and may be 

 cast in moulds. In the silver works of Barnaul, in Kolywan, 

 Siberia, where this method was first devised {Karsten's Arch. 

 3Ietall. V. 1832.) the reducing furnace is 3 feet high, 16 inches 

 broad, 30 inches long above, and 20 below. The opening, which 

 allows the lead to escape, measures 4 inches by 6. There are besides 

 in the anterior part of it three apertures, 2 inches in diameter for the 

 admission of the draught. Several experiments were made at Frei- 

 berg, in 1833, upon this process, and the results were so satisfactory 

 that the method was adopted. The small furnace was built of brick, 

 and the cupellation furnace was placed behind it, so as to form a 

 back to it. To the height of 2 feet, the bricks were cemented, but 

 above this they were simply placed one above the other. When the 

 litharge is pure, it is allowed to run upon the charcoal where it is 

 immediately reduced. The only precaution required, is to see that 

 the litharge falls on the centre of the charcoal. The proportions of 

 the reduced metal to the charcoal burned is 1 quintal (109'81 lbs.) 

 to 2 cubic feet. The expense of the new process is less than a half 

 of the old method. — {Ann. des Mines, vi. 189. 



XII. — Absorption of Oxygen, hy Platinum and Iridium. 



According to Dobereiner these two metals may be obtained in a 

 state of extreme division, by mixing their solution in sulphuric acid 

 with certain organic substances, and then exposing the mixture to 

 the action of light. He has found that when these metals are ex- 

 posed to the air, for the purpose of drying them, the metallic matter 

 absorbs from 200 to 250 times its volume of oxygen, without com- 

 bining with it chemically, and that the latter is condensed with a 

 force equivalent to a pressure of 800 or 1000 atmospheres. This 

 strong mechanical capacity of these metals for oxygen, is an anomaly 

 in chemistry. — {Poggen. Ann. B. xxxi.) 



XIII. — Compounds of Bromine and Oxygen. 



It is well known that it is difficult to produce a combination be- 

 tween bromine and oxygen. Balard of Montpellier, states that this 

 difficulty is overcome by the action of chloride of bromine upon the 

 alkalies, or of bromine alone upon these bodies. Bromine as well as 

 chlorine is capable of acting differently upon the metallic oxides. 

 There are some upon which it has no action, as the peroxides and 

 most of the metals ; with the protoxides, again, it acts by decomposing 

 a part of the body, transforming it into a perbromide, or by separat- 

 ing hydrogen from the water and converting it into perhypobromate. 

 From peroxide of barium, it disengages the additional atom of 

 oxygen, and converts it into the pure alkali. The alkaline oxides. 



