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 were uniformly diffused, 24 cubic metres or 850 cubic feet. When the walls of the room were rendered impervious to air and gas, and acetylene was liberated, and allowed time for diffusion, in the air of the room, an explosion was observed with a proportion of only 2-1/2 per cent. of acetylene in the air. _Solubility of Acetylene in Various Liquids._ _____________________________________________________________________ | | | | | | | | Volumes of | | | | Tem- | Acetylene | | | Solvent. |perature.|dissolved by| Authority. | | | | 100 Vols. | | | | | of Solvent.| | |___________________________|_________|____________|__________________| | | | | | | | Degs. C | | | | Acetone . . . . | 15 | 2500 | Claude and Hess | | " . . . . | 50 | 1250 | " | | Acetic acid; alcohol . | 18 | 600 | Berthelot | | Benzoline; chloroform . | 18 | 400 | " | | Paraffin oil . . . | 0 | 103.3 | E. Muller | | " . . . | 18 | 150 | Berthelot | | Olive oil . . . . | -- | 48 | Fuchs and Schiff | | Carbon bisulphide . . | 18 | 100 | Berthelot | | " tetrachloride . | 0 | 25 | Nieuwland | | Water (at 4 65 atmospheres| | | | | pressure) . . | 0 | 160 | Villard |