The kindling point of acetylene is lower than coal gas or gasoline gas. To ignite either of the latter gases, a flame is necessary to start the combustion, but a spark or a glowing cigar is sufficient to ignite acetylene. It should therefore be borne in mind that acetylene is not only explosive when mixed with air but that it is very easy to ignite. Under ordinary pressures pure acetylene is not explosive, but at pressure above 15 pounds to the square inch explosions sometimes occur where proper precautions are not observed. At all pressures such as are required for household purposes acetylene is as safe for use as any other gas. Although acetylene is in danger of exploding when under pressure, it is perfectly safe, when the proper conditions are observed, in tanks for a great many kinds of portable lights. Where acetylene is used in portable tanks under pressure, advantage is taken of its solubility in acetone. This is a product of the distillation of wood which possesses the property of absorbing acetylene to a remarkable degree. In addition to this property is the more important one of rendering the acetylene non-explosive when under pressure. The tanks for its storage are filled with asbestos or other absorbent material that is saturated with acetone. The acetylene is then forced into the tanks under pressure and is absorbed by the acetone. The safety of this means of storage lies in the degree of perfection to which the tanks are filled with the absorbent material. There must be no space anywhere in the tank where undissolved acetylene can exist. Its freedom from danger under such conditions has been thoroughly demonstrated in its use for railroad and automobile lamps. The use of acetylene as a fuel for cooking and for the various other purposes of domestic use is successfully accomplished in burners that give the blue flame desired for such purposes. Complete cooking ranges and various other heating and cooking devices are regularly sold by dealers in heating appliances, while water-heaters, hot-plates, chafing-dish heaters, etc., are as much a possibility as with any other of gaseous fuel and in as reasonably an inexpensive way. Coal gas, containing as it does sufficient carbon monoxide to render it poisonous, will cause death when inhaled for any length of time, but acetylene under the same conditions will have no deleterious effect.