232 Dr Fyfe on the Illuminating and Heating Power of 



This burner I found by numerous trials, like those previous- 

 ly mentioned, gives heat just in proportion to the consumpt of 

 gas, whether burning with the flames large or small. 



There is still another method of using gas as a source of 

 heat. It is that recommended by Sir John Robison, and de- 

 scribed in the paper alluded to. For this purpose, a piece of 

 fine wire-gauze is placed on a tube of about two or three inches 

 in diameter, and of about thirty inches in length. The tube, 

 open below, is put over the pipe from which the gas issues 

 which, as it escapes, mixes with the air in the tube, and pass- 

 ing along with it through the gauze, is then consumed, the air 

 for the combustion being supplied up through the tube. 



From the results of the trials with the burners already 

 mentioned, there was every reason for believing, that the heat 

 afforded would be the same when the gas was consumed on 

 gauze, but as the general impression is the reverse, it was ne- 

 cessary to put it to the test of experiment. 



In the different trials, I made use of gauze of various dia- 

 meters, on tubes of different lengths, and also consumed the 

 gas, sometimes with the flame barely visible in day light, at 

 other times with more or less admixture of white. The water 

 in the boiler, as before, was a quarter of a gallon, at tempera- 

 ture 45. With gauze of three inches diameter, on a tube of 

 twenty mches in length, the gas burning with a blue flame a 

 little way up in the cavity of the boiler, half a foot, in fifteen 

 minutes, water rose to 145. 



In another trial, the flame on the gauze being larger, the 

 same quantity of water was raised to 151. In numerous other 

 trials, the temperature varied a little, the elevation ranging 

 from 145 to 150. The discordance in the results may be sa- 

 tisfactorily accounted for from the manner in which the flame 

 was placed. When large, it cannot be all within the cavity of 

 the boiler ; of course there is a considerable loss, and there is 

 also frequently an escape of part of the gas unconsumed, either 

 owing to its not being thoroughly mixed with air, or owing to 

 the products of combustion not being carried off with sufiicient 

 rapidity, by which the perfect combustion is prevented. Hence 

 the difficulty of getting accurate results when the gas is burn- 

 ed in this way. We may, however, from the experiments, 



