MINE SAFETY DEVICES — MANNING. 543 



Moreover, the use of the detector is not limited to mines or to 

 detecting fire damp, but it can be used for proving the presence of 

 any combustible gas, such as gasoline vapor, hydrogen, natural gas, 

 or coal gas. 



Essential^, the detector consists of a U-tube, one branch of which 

 is inclosed in a metal case, as shown in the accompanying photograph 

 (pi. 6). To make the device ready for use the top a is unscrewed 

 and water is poured in until it fills the two branches and rises to the 

 zero point h on the scale. 



To make a determination of combustible gas, say methane, in mine 

 air, the valve c is opened, and by blowing gently into the reservoir 

 the operator depresses the water column along the scale and forces it 

 up to the top on the other side. A slight click when the water strikes 

 the valve c tells the operator that it has risen to the required height. 

 Then the operator pinches the rubber tube d and takes the instru- 

 ment to the place where the sample is to be collected. When the 

 pressure on the rubber tube d is released, the water immediately comes 

 back to its original position, and on falling sucks through the valve c 

 a sample of the air to be tested. 



This sample rests in the combustion chamber e in contact with a 

 platinum spiral. The valve is closed and the spiral is electrically 

 heated by use of the binding posts /. Any combustible gas in the 

 sample immediately begins to burn and at the end of a minute and a 

 half is completely consumed. The electric current is then turned oif 

 and the instrument is shaken, thus forcing the water into the com- 

 bustion space e and cooling the gases. Immediately the water column 

 on the open-tube side falls to some point on the graduated scale as a', 

 the exact point depending on the percentage of methane present. 

 The scale reading opposite the water level shows the percentage. 



The platinum wire can be heated by means of the storage battery 

 of a miner's electric cap lamp, the battery being carried on a man's 

 belt, and the current being switched from the lamp to the detector, as 

 the tests are made. 



The device is 10 to 20 times as accurate as the safety lamp, weighs 

 less, and has fewer and more durable parts. 



PORTABLE APPARATUS FOR RAPID DETERMINATION OF INCOMBUS- 

 TIBLE MATTER IN ROAD AND RIB DUSTS FROM COAL MINES. 



In applying rock dust in mines it is necessary to determine quickly 

 and on the spot the approximate percentage of noncombustible 

 matter in the road and rib dust in order to determine how much ad- 

 ditional limestone or shale dust is required to prevent the propaga- 

 tion of dust explosions. 



For this purpose the Taffanel volumeter has been modified and 

 combined with a convenient portable field equipment. The complete 



