^0 PROCEEDINGS OF THE CANADIAN INSTITUTE. 



flame, and convection of tlie completely burnt products of combus- 

 tion, the most intense temperatures can be transferred in all manu- 

 facturing processes, with surprising economy in fuel, with increased 

 length of life in furnace, and in metallurgy and glass-making, &c., 

 with a greater percentage of finished product per unit of crude mate- 

 rial used. 



This commercial success is obtained by making the combustion 

 chamber or furnace so very large that the flame cannot touch either 

 walls or material to be heated, and thus its activity is not quenched 

 when but partial combustion has taken place, as is the case if it 

 touches any solid substance, whatever be the temperature of that 

 substance. 



This is a complete revei-sal of the old-fashioned and still prevalent 

 idea that, for instance, a boiler should be set as close to the fire as 

 possible, so that the flame may inpinge directly on the evaporating 

 surface, or on the material to be heated. 



Mr. Siemens last year, at the Chester meeting of the Iron and Steel 

 Institute, said : " The interruption of the process of combustion by 

 " the interposition of solid bodies always tends to injure, or even 

 "'•' destroy them. 



" But, besides the circumstance that solid bodies are injured by 

 ^' flame, it can be easily shown that when flame is brought into con- 

 " tact with any solid body, it is more or less quenched according to 

 " the substance, size, and temperature of the body. A very simple 

 •''experiment in pi-oof of this, and one which is familiar to most 

 " people, is the following : — Take any ordinary illuminating gas 

 '' flame, such, for instance, as a bat's wing, and place a glass rod or 

 ^' tube into the middle of it ; the flame will immediately burn dull, 

 " and a large quantity of lamp-black will be deposited on the piece 

 '■' of glass. This action is most marked when the rod is cold, but 

 " takes place, though in a less degree, at any temperature, for the 

 -' reason that the material to be heated is necessarily always at a 

 " lower temperature than the flame, also owing to the disturbance 

 '' in the combustion caused by contact of the solid substance with 

 " the flame." 



His experiments " estaVJish the following important fact, namely, 

 " that a good flame, or, in other words, perfect combustion, can only 

 " take place in an open space, or in one of sufliciently large size to 

 " allow the gases to burn out of contact with solid material." 



