1893.] A New Portable Miners Safety-lamp. 501 



The gas was thoroughly mixed with the air, partly by the action of 

 the fan, and partly by the passage of the air current through coarse 

 wire-gauze baffles, C. The lamp was introduced through a hinged 

 window, D. 



The hydrogen flame in the Ashworth's lamp was not affected in 

 the least by this air-current. The cap shown over the flame indicated 

 the presence of 0'5 per cent, of gas. At a given signal the hinged 

 door E was dropped into position EI, and closed the tube, and the fan 

 was simultaneously stopped. The lamp was thus exposed to still air 

 of the same composition as that which was previously in motion. 

 Not the slightest effect upon the flame or cap was perceptible. 



A similar experiment made with the reduced oil flame of the lamp, 

 and with air containing a larger percentage of gas, showed that the 

 air-current in motion produced no effect on the oil flame and its cap 

 other than the quiescent air of the same composition did. 



It may be concluded, therefore, that with a good safety-lamp the 

 test-chamber indications are applicable to the conditions ordinarily 

 found in the mine. 



[February 7. It was found, however, that the presence of fine 

 -coal-dust in very large proportion in the air rendered the test-flame so 

 luminous that no cap could be seen even when gas was present. A very 

 dusty atmosphere will render gas-tests impossible by all the forms of 

 testing apparatus at present known. No interference arose from the 

 dust ordinarily met with in the mine.] 



Results of Flame-cap Measurements in Air containing Water-gas. 



The poisonous nature of " water-gas," which is produced by passing 

 ;steam over red-hot coke or charcoal, is well known. It is due to the 

 large proportion of carbon monoxide present in the gas. Since 

 water-gas is free from odour, it is very necessary to find, if possible, 

 some delicate method of detecting it and of measuring its amount in 

 .air. Accordingly the heights of the flame-caps yielded by the hydro- 

 gen flame and by the oil flame of the safety-lamp, when the lamp 

 was introduced into air containing known percentages of water-gas 

 in the test-chamber, were measured. It was hoped that the flame-cap 

 test might prove available for water-gas, as it is for firedamp and for 

 coal-gas. 



The samples of water-gas were prepared in the laboratory by pass- 

 ing steam over red-hot wood charcoal contained in a porcelain tube. 

 The flame-indications proved that portions of the gas collected at 

 different periods of the preparation were very different in composi- 

 tion ; and a chemical analysis of the gas showed an undue proportion 

 of carbon dioxide and a deficiency of carbon monoxide. The percent - 



2 L 2 



