Proceedings of Learned Societies, 



ROYAL INSTITUTION". 



Gas Glass Furnaces. — At the last Friday evening meeting of 

 the Members of the Royal Institution, Professor Faraday delivered 

 a lecture, explanatory of the construction and mode of action of Mr. 

 Siemen's gas glass furnaces. In these furnaces the gaseous fuel is 

 produced by the combustion of coal in a limited amount of air; the 

 products of the combustion which takes place at the lower part of 

 the furnace having to pass a layer of unignited coal are decomposed ; 

 the carbonic acid is reduced to a state of carbonic oxide by taking 

 up an additional quantity of carbon ; various gaseous hydrocarbons 

 are also liberated by the heat acting on the coal, and by the intro- 

 duction of water into the burning fuel steam is produced, which is 

 decomposed by the heated carbon yielding carbonic oxide and 

 hydrogen. The mixed gaseous fuel thus produced passes off from 

 this furnace ; it consists of the nitrogen derived from the air ; this 

 constitutes about one third of its bulk, and is a useless ingredient 

 as possessing no calorific power whatever ; the remaining two con- 

 sist of a somewhat varying admixture of hydrogen, carbonic oxide, 

 and gaseous hydrocarbons. This gaseous fuel is allowed to ascend 

 a vertical tube, and may be conveyed to any required distance before 

 it is mino'led with air and allowed to burn. Such is the areneral 



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principle of the action. In the furnaces of Mr. Siemen there are, 

 however, certain contrivances, termed by him regenerators, by the 

 aid of which the heat produced is encouraged in its distribution, so 

 that but little of it escapes being utilized. Hence the economy of 

 fuel is estimated, practically, at one half. 



The explanation of the value of this process depends on the 

 calorific or heat-giving power of the substances burnt. One part of 

 carbon, if perfectly oxidized, unites with two and two-thirds of 

 oxygen to form carbonic acid C0 2 , and evolves sufficient heat to 

 raise the temperature of 8000 parts of water one degree centigrade. 

 If it burns in a limited supply of oxygen so as to produce carbonic 

 oxide, the CO, the amount of heat evolved, would only raise the 

 temperature of 2473 parts of water one degree ; but when this 

 amount of carbonic oxide is allowed to burn in a fresh access of 

 air, it evolves the remaining units of heat (viz. 5607) required to 

 make up the 8000 produced by the perfect combustion of carbon. 



The calorific power of the hydrogen is very high — being 34,000 

 as compared with carbon 8000, and that of the hydrocarbon pro- 

 duced may be taken in round numbers at over 12,000; hence the 

 heating power of the whole mixed gaseous fuel is equal to that of 

 an equal weight of carbon ; and as it is capable of being applied so 

 much more advantageously, owing to its gaseous form, its practical 

 value is in reality much greater. 



