1S65.] Mining, Mineralogy, and Metallurgy. 307 



country during 1864. We are informed, however, that it will be 

 slightly less than the quantity produced in 1863. The production of 

 iron ore has been large, and the make of iron somewhat in excess of 

 the previous year. 



Mr. Villiers announced in the House of Commons that the Bill 

 which he intended to bring forward to make metalliferous mines 

 ratable to the poor, would be postponed to the next Session. This had 

 been determined on to avoid interfering in any way with an Inspection 

 Bill, which is being prepared by the Mines Commission, and which we 

 understand will shortly be brought into the House of Lords by the 

 Chairman of that Commission. It is essential that some legislative 

 measures should be brought into action for the purpose of checking the 

 spread of carelessness which is evident in our metal mines. 



From time to time, attempts have been made to use electricity as 

 an illuminating ageni in coal mines, especially in such as produced 

 so large an amount of fire-damp as to be dangerous. As the electric 

 arc could be maintained in vacuum, or in a vessel of water — and, as the 

 luminous current could be instantly stopped by breaking connection 

 with the battery, — it was thought to possess elements of safety which 

 belong to no other method. Not one of the numerous trials which 

 were made was successful, and the idea was abandoned. The in- 

 duction coil of Bbumkorff appeared, however, to open the question 

 anew ; and, when the beautiful phenomena of electric illumination in 

 the rarefied media of Geiseler's tubes had been witnessed, the possi- 

 bility of having light without heat, and consequently of forming a per- 

 fect safety-lamp was evident. 



MM. Dumas and Benoit have constructed an electric lamp, 

 founded on the advantages presented by Khumkorff's machine, and 

 Geiseler's tube, and they have made some trials with the lamp in 

 several of the French collieries, which are stated to have been suc- 

 cessful. It will be interesting to describe this lamp. The electricity 

 is generated by a modification of the old bichromate of potash 

 battery, consisting simply of a zinc vessel, a porous cylinder, and a 

 roll of carbon, charged with a solution of the bichromate of potash, 

 and dilute sulphuric acid. This arrangement is carefully secured in a 

 case, with a wooden cover, made to fit tightly by means of India- 

 rubber. Next, there is a BkumkorfFs coil and condenser, placed in a 

 stout leather case, and then the Geiseler tube, which is very slender, 

 and for the purpose of getting the largest possible amount of surface is 

 arranged as a conical coil. This delicate tube is enclosed in a case of 

 thick glass, protected by a suitable metal framework. It will now be 

 understood that the lamp consists of three parts — the battery, the coil 

 machine, and the tube — the whole together weighing about fourteen 

 pounds. By means of straps, this apparatus is arranged around the 

 miner, and provisions have been made by the inventors by which he 

 may be relieved of this weight, and the tube used at a distance from 

 the battery and the coil. 



There can be no doubt but under circumstances of extreme danger, 

 that this lamp may be useful. An explosive atmosphere may be 



