APPARATUS FOR THE ELECTRIC LIGHT. 131 



;gence, who was then most enthusiastic as to the results ob- 

 tained by his machines : 



. . . I ought to have written sooner to tell you about the 

 machine: it works perfectly well and with increasing power, and 

 we have an admirable light. I wanted to tell you of this, which 

 I consider of consequence, for, as usual, we have to thank you 

 for this important matter. You induced me to see Jacquelain 

 about his pure carbon coke, and this coke gives a steady light 

 without flame, and of remarkable brilliancy. I am sorry you 

 are not here, as you have been kind enough to bestow a fatherly 

 care upon our machine. This evening I am showing the light 

 to my superintending committee. We are able at a distance of 

 60 metres to read very small writing, and no doubt we could 

 read at nearly a kilometre if space permitted. We have also 

 magnificently illuminated the dome of Les Invalides, which is 

 about 300 metres from our apparatus ; but I hope we shall soon 

 perform the experiment on the Seine in a steamboat, as you 

 advised. 



Thus with our machine taking the place of the voltaic pile, 

 with the Jacquelain carbons, a regulating mechanism suited for 

 alternately contrary currents, and a good reflector, the problem of 

 < electric lighting on sea-going ships will be completely solved. 



Jacquelairis Method. To obtain a pure carbon Jacque- 

 lain makes use of the carbides of hydrogen, either those 

 obtained in the distillation of coals, shales, turf, &c., or the 

 ; numerous products formed during the carbonization of these 

 combustibles in close vessels, or those represented by the 

 heavy coal, shale, or turf oils, or by volatizable organic sub- 

 rstance. 



" These organic materials," says Jacquelain, " contained in a 

 cast-iron receptacle, are introduced into a cast-iron boiler on a 

 lower level by a conducting pipe furnished with a cock. The 

 boiler is also provided with a cock for emptying it. The vapours 

 are carried by a cast-iron pipe into a horizontal retort made of 

 refractory earthenware, and fitted with a screen for retarding 

 the passage of the gaseous products. This communicates with 

 -two cast-irons receivers, forming an inverted U, where the lamp 



92 



