112 ANNUAL OF SCIENTIFIC DISCOVERY. 



stances which give scarcely any light, are remarkable for their heating pro- 

 perties. Thus alcohol and pure hydrogen gas give but little light, while their 

 heat is very much greater than that of the bright, shining flame of a candle 

 or lamp. It is evident, then, that the production of light and heat involves 

 principles which require entirely different contrivances when we desire to 

 obtain the best effects. 



"When carbureted hydrogen gas is used for illumination, the light is due to 

 the combustion of the carbon with the hydrogen of the gas, and the oxygen 

 of the atmosphere. As the action of the oxygen is confined to the exterior 

 surface of the gas, the greater the surface exposed, in proportion to the bulk 

 or volume of the gas, the more brilliant will be the light ; to attain this 

 object, the gas is usually thrown from the jet in the form of a thin sheet, as 

 in the "bat wing," or in a thin ring, as in the "argand" burner. There is, 

 however, a limit to the tenuity of this sheet or ring, from the necessity of 

 having a sufficient volume of gas, to allow a large number of particles of 

 carbon to become ignited at the same tune, because it is from their ignition 

 that the light proceeds. 



Under these circumstances, more gas generally passes through the jet than 

 is consumed, and the proportion which is thus wasted depends upon the purity 

 of the gas, and the construction of the jet from which it is burned. It is a 

 natural inference, therefore, that the most wasteful method of using gas, either 

 for light or fuel, would be to burn it from separate, round-hole jets, because in 

 this form there is less of the gas exposed to the action of the oxygen than in 

 any other. 



Having thus explained the process of illuminating by gas, let us now 

 examine how these principles should be modified so that the gas may be used 

 to the best advantage for fuel. In this case, heat is the sole object, and the 

 perfection of any process would be to consume all the gas, and be able to con- 

 trol all the heat which it evolves. To obtain this result, as far as possible, it 

 is essential, 1st. That not the surface only, but all the particles of the gas, 

 should be brought in contact with the oxygen. 2d. A due regard to economy 

 requires that no draft should be created around the jet by heat or otherwise, 

 by which the gas will issue irregularly, causing a greater consumption of gas 

 at one tune than another. 3d. The products of consumption should be made 

 to add to the heat, or be so disposed of as to prevent any unpleasant or 

 noxious effluvia from passing off. 



IMPROVEMENTS IN GAS APPARATUS. 



Shades for Lamps and Gas Lights. H. Gillen, of London, has taken out a 

 patent for making globes and shades composed of prisms of glass. They are 

 strung together, and made to assume the proper form on a frame. By 

 varying the shape of these prisms, very beautiful and novel effects are 

 produced. 



Improved Gas Apparatus. Mr. A. Longbottom, of London, has obtained a 

 patent for constructing retorts for making gas from oil, with an interior cone 

 hi each, and convex on the outside, to contain the fire. Each retort has also 

 a false perforated bottom, under which is placed a mixture of charcoal and 



