It is obvious that in using the oxycalcium jet the operator is dependent for his flame upon a supply of the ordinary hydrogen or street gas, and therefore this modification of the oxycalcium apparatus cannot be employed in any place unprovided with the means of obtaining the same. The oxycalcium lamp, on the other hand, as it carries with it the means of producing the required flame, can be used anywhere. The light obtained by the oxycalcium arrangement, although not equal to the oxyhydrogen light, is admirably adapted for exhibitions on a moderate scale, and it requires only one gas-bag.
In both of the oxycalcium arrangements the lime cylinder does not need any alteration of position while in use. The proper distance between the oxygen jet and the surface of the lime varies from one-eighth of an inch to one-quarter of an inch.
Having explained the oxycalcium lamp and jet, we have now to describe the oxyhydrogen jet, by which the brightest form of lime-light is produced. The oxyhydrogen jet differs from those previously described in one important particular, viz. that the two gases are mingled together as gases before being ignited. Like the oxycalcium jet, it consists of two tubes lying side by side (see Fig. 7), having a tap at one end of each. The ends of these tubes are inserted into the base of a small chamber, from which proceeds a single curved tube, which rises up in front of the holder upon which the lime cylinder is placed. The end of this tube is contracted by a platinum point screwed into it, and this forms the jet. Two bags are required for this light, one containing hydrogen gas (common house gas will do), and the other bag filled with oxygen gas, and these bags are to be connected with the taps at the end of the jet by means of flexible tubes in the usual manner. The two gases are thus kept separate until they enter the chamber at the base of the curved pipe. This chamber is provided with layers of wire gauze, so as to facilitate the admixture of the gases, which eventually issue thoroughly mingled from the point of the jet. In this condition they are capable of being ignited, and as soon as the flame impinges on the lime cylinder a most intense light results.