2 Dixon & Lowe, Ex/^critncnts on AbeFs theory. 



Special experiments demonstrated that "some per- 

 fectly non-combustible powders are very little inferior to 

 the most inflammable or sensitive of the Seaham dust- 

 samples " in their power to bring about the ignition of an 

 otherwise uninflammable mixture of firedamp and air. 



Abel's experiments were carried out in a long wooden 

 galler)- fitted with observation windows. At one end was 

 a Korting's blower, capable of drawing air through the 

 gallen,' at any rate up to i.ooofL per min. Near the 

 opposite end the gas entered by a pipe fitted into the 

 bottom of the galler)-. The stream of gas and air passed 

 a drum sieve, which on rotation allowed a supply of dust 

 to fall into the gases below. About twelve feet further 

 along the current passed the naked flame of a Davy 

 lamp, or a gas flame. Air and gas in the ratio of 3% 

 fire-damp to 97^^ air were passed through the galler>' at a 

 rate of 600ft. per minute. The lamp-flame produced no 

 effect on this mixture, but when calcined magnesia was 

 conveyed into the current, long '* flares " of flame were 

 seen on the lamp-flame, and "inflammation speedily spread 

 through the gallery with feeble explosive effect." With 

 275'. fire-damp quite similar results were produced, but 

 the general inflammation followed less rapidly after the 

 first flares were observed. Other incombustible dusts, 

 such as pumice, kaolin, etc, produced similar results, but 

 some more rapidly than others. 



These results Abel explained in the following manner : 

 " The instantaneous raising of such small dust particles 

 to incandescence by the flame must have the effect of 

 localising, and consequently intensifying, the heat at those 

 points ; and the ignition of the gas greatly diluted with 

 air may thus be brought about." The action is compared 

 to the contact, or catalytic action of platinum, which, 

 when it " is brought into contact with a mixture of 



