Technical Chemistry. 277 



tare. The chlorine may also be separated from its chlorids by potassium 



verv energetic. 



The small ingot, weighing fourteen grammes, which I had the honor 

 of exhibiting to the Academy, was entirely isolated by a battery of a few 

 Bunsen elements, first from the chlorids originally obtained, and then 

 from the crystallized sulphate formed directly by the solution of this 

 thallium iu pure sulphuric acid. * * 



gaps at present wanting in its history.— CAcmica/ Mews, July 19, 1862. 

 Ikhmcal Chem.stry.- 

 4. Regenerative Gas Furnace. — Mr. Siemens of London has contrived 



he calls a regenerative gas furnace adapted to glass houses, iron 

 ng, and all kinds of furnaces, where long continued high heats 

 e copy Prof Faraday's notice of this invention as c 

 Royal Institution of Great Britain, June 20, 1862. 



"The subject of the evening was g; ^ . , 



almost extemporaneously, it resolved itself chiefly into an account of the 

 nianner in which Mr. Siemens has largely and practically applied gas, 

 «oinbined with the use of his heat-regenerator, to the ignition of all kinds 

 of great furnaces. Gas has been used to supply heat, even upon a very 

 large scale, in some of the iron- blast-furnaces; and heat which has done 

 ^0""k once has been carried back in part to the place from whence it 

 came to repeat its service ; but Mr. Siemens has combined these two 

 Pomts, and successfully applied them in a great variety of cases— as the 

 potter's kiln, the enameller's furnace, the zinc-distilling furnace, the tube- 

 welding furnace, the metal-melting furnace, the iron-puddling furnace, 

 and the glass-furnace either for covered or open pots— so as to obtain the 

 highest heat required over any extent of space, with great facility of man- 

 agement, and with great economy (one-half) of fuel. The glass-furnace 

 described had an area of 28 feet long and 14 feet wide, and contained 

 «'ght open pots, each holding near two tons of material. 



Ine gaseous fuel is obtained by the mutual action, at a moderate red 

 '^^at, of coal, air, and water. A brick chamber, perhaps 6 feet by 12, 

 *"d about 10 feet hio-h has one of its end-walls converted into vl ^re- 

 fate; i. e. about halfway down it is a solid plate, and for the rest of the 

 distance consists of strong horizontal plate-bars where air enters, the 

 *nole being at an inclination such as that which the side of a heap of 

 «oals would naturally take. Coals are poured, through openings above, 

 «Pon this combination of wall and grate, and being fired at the under 

 ^"fface, they burn at the place where the air enters ; but as the layer of 

 J°al 18 from 2 to 3 feet thick, various operations go on m those parts of 

 ^^e fuel which cannot burn for want of air. Thus the upper and cooler 

 Paft of the coal produces a larger body of hydrocarbons; the cinders or 

 ^« which are not volatilized approach, in descending, towards the 

 F^te; that part which is nearest the grate burns with the entering air 

 ;;to carbonic acid, and the heat evolved ignites the mass above it; the 

 ^ai-bonic acid, passing slowly through the ignited carbon becomes con- 

 ]^'^ into carbonic txyd, and minlles in the upper part of the chamber 

 l<^' gas-producer) with the former hydrocarbons. The water, which is 



