134 ELECTRIC LIGHTING. 



by the Jablochkoff Company, been much extended, and,, 

 thanks to the large scale on which his process is being carried 

 out, he can now send out carbons 50 per cent, better than at 

 first. These carbons are now at a price which allows of their 

 practical use, and this circumstance greatly conduces to the 

 development of the applications of the electric light. 



Gauduin' s System. The carbons manufactured byGauduin 

 are of pure carbon, their base being lamp black ; but as 

 the price of this substance is comparatively high, and its 

 management is difficult, Gauduin was obliged to seek for 

 a better source of carbon, and he obtained it by heating in 

 a closed vessel common rosin, pitch, tars, resins, bitumens, 

 natural and artificial oils, essences, or organic matters, 

 which, after decomposition by heat, leave sufficiently pure 

 carbon. 



These products are put into crucibles and heated to bright 

 redness, the volatile matters being conducted into a con- 

 densing chamber, whence they are carried by a copper worm- 

 tube with the condensed liquids, such as tars, oils, spirits, 

 and carbides of hydrogen, into another worm-tube, where 

 they are collected for use in the manufacture of the carbons. 

 There remains in the retort some more or less compact car- 

 bon, which is pulverized as finely as possible, and collected 

 either alone or mixed with a certain quantity of lamp black 

 by means of the carbides of hydrogen obtained as secondary 

 products. 



Thus prepared, these carbons are completely free from 

 iron, and are superior to those met with in commerce. For 

 moulding his carbons the inventor uses steel moulds capable 

 of withstanding the highest pressure of a powerful hydraulic 

 press. The moulds are arranged like draw-plates, and their 

 arrangement has been much improved by Gauduin, for in his 

 process the sticks are supported throughout their whole 

 length, so that they do not break by their own weight, as 

 often happens with ordinary draw-plates. 



Quite recently Gauduin has further improved his process. 



