1 82 THE SCIENTIFIC PAPERS OF 



iron, or whatever it may be. For such purposes the whole of the 

 solid coal ought to be converted into gaseous fuel, and that has 

 been accomplished for many years. It is accomplished in the blast 

 furnace, where the combustion of coke under the influence of an 

 insufficient amount of blast gives rise to a product at the top, 

 consisting, in a great measure, of carbonic oxide gas mixed with a 

 large proportion of nitrogen, which necessarily comes in with the 

 air at the bottom. It is due chiefly to Mr. Ebelmen, a French 

 physicist of some distinction, that attention was called to these 

 gases in the early part of the century, but no practical application 

 was made of gas for a number of years, nor were the gases coming 

 from the blast furnace practically utilized until within the last 

 twenty-five years. 



In the year 1861, I, in connection with my brother Frederick, 

 succeeded in the construction of a regenerative gas furnace in 

 which gas is used resulting from the total destructive distillation 

 of coal, and I now wish to place before you an apparatus of an 

 improved character for effecting that purpose. The gas-producer 

 which we have hitherto used was effective, so far as it goes, in 

 producing a combustible gas, but it did not fulfil all the conditions 

 necessary to produce this chemical operation to the best advan- 

 tage. One of the essential conditions for the total conversion of 

 coal into combustible gas is a maximum degree of heat at one 

 portion of the process. Where air enters, or is forced into a 

 mass of incandescent fuel, the temperature of that fuel is raised, 

 and the result of perfect combustion is carbonic acid. In order 

 to produce carbonic oxide, which is the gas fuel producible from 

 the carbonaceous constituent of the coal, it is absolutely necessary 

 that carbonic acid, or the result of perfect combustion, should be 

 produced in the first instance, and only by passing this intensely 

 heated carbonic acid over an additional mass of incandescent 

 carbon will it take up another constituent of carbon, and con- 

 stitute itself carbonic oxide ; unless the temperature is high 

 enough, this reconversion, or backward conversion from carbonic 

 acid into carbonic oxide, will be effected only partially and 

 imperfectly. 



The apparatus, Plate 33, which I have lately tried, and which pro- 

 mises to be a great improvement on the former arrangement, consists 

 of a cylindrical chamber truncated towards the bottom, which is 



