Acetylene, the Principles of Its Generation and Use

Excerpt: ...however, with the mixture dry instead of saturated with aqueous vapour, which doubtless helps to account for the difference between his and Eitner's results. Table giving the Percentages by volume of Combustible Gas in a Dehydrated Mixture of that Gas and Air between which the Explosive Limits of such a Mixture lie.-(Teclu). ____________________________________________________________________ Lower Explosive Limit. Upper Explosive Limit. Description of ________________________________________________ Combustible Gas. Per Cent. of Gas. Per Cent. of Gas. __________________________________________________________________ ACETYLENE 1.53-1.77 57.95-58.65 Hydrogen 9.73-9.96 62.75-63.58 Coal-gas 4.36-4.82 23.35-23.63 Methane 3.20-3.67 7.46- 7.88 __________________________________________________________________ Experiments have been made at Lechbruch in Bavaria to ascertain directly the smallest proportion of acetylene which renders the air of a room explosive. Ignition was effected by the flame resulting when a pad of cotton-wool impregnated with benzoline or potassium chlorate was fired by an electrically heated wire. The room in which most of the tests were made was 8 ft. 10 in. long, 6 ft. 7 in. wide, and 6 ft. 8 in. high, and had two windows. When acetylene was generated in this room in normal conditions of natural ventilation through the walls, the volume generated could amount to 3 per cent. of the air-space of the room without explosion ensuing on ignition of the wool, provided time elapsed for equable diffusion, which, moreover, was rapidly attained. Further, it was found that when the whole of the acetylene which 2 kilogrammes or 4.4 lb. of carbide (the maximum permissible charge in many countries for a portable lamp for indoor use) will yield was liberated in a room, a destructive explosion could not ensue on ignition provided the air-space exceeded 40 cubic metres or 1410 cubic feet, or, if the evolved gas...