86 . Biographical Account of 



He published the results of his experiments in the Philo- 

 sophical Transactions, in a series of papers, which rapidly 

 succeeded each other, and afterwards collated them into a 

 work entitled " On a safety lamp for preventing explosions 

 in mines, houses lighted by gas, spirit warehouses and 

 magazines, in shops, (fee. ; with some remarks on flame." 



The important discovery which resulted from these inves- 

 tigations, was begun by an accurate inquiry into the 

 properties of carburetted hydrogen or fire damp — although 

 most of them had been well studied by Dal ton, Thomson, 

 and Henry ; he found that it required a large quantity of 

 atmospheric air for explosion ; that it was the least readily 

 combustible of all the inflammable gases, or required the 

 highest temperature, and that its expansive effect from 

 heat, was less than that of other gases. He observed, that 

 mixing one part of carbonic acid, or fixed air, with seven 

 parts of an explosive mixture of fire damp or one part of 

 azote with six parts, their powers ofexplosion were destroyed. 

 He observed also, that in exploding a mixture in a glass tube 

 of one fourth of an inch in diameter, and a foot long, more 

 than a second was required before the flame reached from 

 one end to the other, and that in a tube of one seventh of an 

 inch in diameter, explosive mixtures could not be fired when 

 they were opened in the atmosphere, and that metallic tubes 

 prevented explosion better than glass tubes. " In reason- 

 ing upon these various phenomena," he observes, '* it 

 occurred to me, as a considerable heat was required for the 

 inflammation of the fire damp, and as it produced in burning 

 a comparatively small degree of heat, that the efi*ect of car- 

 bonic acid and azote, and of the surfaces of small tubes in 

 preventing its explosion depended upon their cooling 

 powers, upon their lowering the temperature of the ex- 

 ploding mixture so much, that it was no longer sutficient 

 for its continuous inflammation." "This idea, which was 

 confirmed by various obvious considerations, led to an 

 immediate result, the possibility of constructing a lamp, in 

 which the cooling powers of the azote or carbonic acid, 

 formed by the combustion or the cooling powers of the 

 apertures through which the air entered and made its exit, 

 should prevent the communication of explosion." The 

 consequence was, the invention of the safety lamp — a cage 



