416 



Mr. W. Galloway on the 



[Mar. 13, 



water, but it contains innumerable globules of water floating in it. On 

 the 5th of October last its temperature was 69° '3 F. An oil lamp, 

 having a good large flame, was placed inside the door n, so that the 

 flame was in the centre of the current, and it was then found that the 

 temperature of the air had increased to 74° '5. The temperature, 

 quantity, and quality of the various currents of return air in this 

 colliery were, on the 11th of April, 1878, as follows : — 



Date upon which 

 the observation 

 was made. 



Number 



of 

 current. 



Cubic feet 

 of air per 

 minute. 



Tempera- 

 ture Fahr. 



Height of 

 cap on 

 small 

 flame. 



Approximate 

 percentage 



of fire-damp 

 in the air. 



1878. 







Dry. 



Inch. 





April 11 . , . . 



1 



10,128 



66° 



¥ 



2 per cent. 



2 



21,000 



74° 









3 



44,421 



73° 



f 



m „ 







75,549 









The elevation of temperature due to placing the lamp inside the 

 apparatus is, therefore, not abnormal. The hopper having been filled 

 with coal-dust the plug was raised somewhat and stirred about so as 

 to determine the entry of dust into the chamber h. The immediate 

 result was the appearance of a large and very hot red flame at the 

 mouth of the pipe d. The length of the visible part of the flame 

 varied from 6 to 8 feet, and its greatest diameter from 2 to 24 feet ; 

 and it was accompanied by large volumes of black smoke and dust. 

 The pipe cl soon became so hot that it could not be approached closely. 



The second experiment is intended to illustrate the effects of an 

 explosion of fire-damp in a dry mine containing coal-dust. One part 

 of the apparatus represents a gallery with coal-dust lying on its floor 

 as well as on the horizontal timbers, the buildings, and other rough 

 surfaces at its top and sides ; another part represents a cavity in the 

 i-oof containing an explosive mixture of fire-damp and air. When the 

 explosive gas is ignited the flame sweeps down into the gallery, the 

 disturbance raises the coal-dust and the results are exactly those that 

 have been foreseen. Figs. 2 to 6 show all that is necessary for under - 



Fig. 2. 



