CHEMICAL SCIENCE. 203 



pedient. The apparatus is a cast iron retort of convenient form, made, it 

 may be, to be set upright and to be charged at the top, or to lie horizontally, 

 like the retorts of the gas-houses, in which case the charging door would be 

 in the front, a sloping entrance leading down into the tipper portion of the 

 retort. The articles to be converted into steel are placed one upon another 

 in this vessel, and sufficient soda is introduced to flow over and cover them 

 as it melts. It is not necessary that the articles should be kept immersed in 

 the liquid soda, the most satisfactory results having been obtained even 

 when a considerable portion of the soda, after once covering the bars, had 

 been allowed to escape. The retort itself becomes decarbonized, con- 

 verted into steel, and finally into malleable iron. In this condition it may 

 continue in use for many firings; and considering the low heat employed, 

 there is little doubt it can be made almost permanent. N. Y. Tribune. 



MELTING ZINC BY MEANS OF GAS. 



A report has been made to the Society for the encouragement of National 

 Industry (France) upon the method of melting zinc by means of ordinary 

 illuminating gas, proposed by M. Miroy. The results are interesting to zinc- 

 founders, type-founders, and those engaged in melting and casting tin, 

 lead, or the fusible alloys of these metals. AVe translate the following from 

 the report : 



The melting of zinc, which is generally made in crucibles of plumbago, 

 and in a coke or coal fire, involves a very elevated temperature, difficult to 

 regulate, and a consequent loss of metal by volatilization and combustion. 

 The metal also acquires bad qualities, which workmen attribute to its being 

 burned or scorched, but which appear to be due to the mechanical penetra- 

 tion of the oxide of zinc into the pores of the metallic mass. The melted 

 metal then presents a pasty consistence, and the action of the chisel and the 

 file becomes more difficult upon the casting, owing to the alteration of the 

 malleability. 



To remedy these disadvantages, M. Miroy fuses zinc by gas. His appa- 

 ratus consists of a crucible of cast iron, which may contain thirty to thirty- 

 five kilogrammes of zinc. This is placed in a cylindrical furnace of conical 

 form, where it is exposed to the combustion of ordinary illuminating gas, 

 which enters obliquely on two sides by two tuyeres. These are each concen- 

 tric with larger tuyeres, through which air is forced by means of a blower 

 driven by the machinery of the establishment. The interior diameter of the 

 smaller, or gas tuyere, is eighteen millimetres; those of the air, seven centi- 

 metres. The volume of air used has not been determined, but is estimated 

 to be to that of the gas as three to one. The inventor thinks that by this 

 method zinc may be melted more rapidly and cheaply than by coke, while 

 the heat may be so regulated as not to injure the metal. There is also a 

 great saving in the cost of crucibles. Repertoire de Chimie. 



ON THE EMPLOYMENT OF THE METAL MAGNESIUM AS AN ILLUMI- 

 NATING AGENT. 



It has recently been proposed by M. Bunsen, of Paris, to employ the metal 

 magnesium for producing light by its combustion. This metal, it is well 

 known, is the base of magnesia, as aluminum is of alumina. It is, however, 

 much less known than the latter, although it is but a short time since both 



