A section of the gas-producer is shown in fig. 1: _a_ is a leaden tank, for containing dilute sulphuric acid; _b_, a pipe which passes from the acid vessel to another similar leaden vessel, _c_, which is to contain cuttings of zinc; _d_ is a conical plug, with a stalk and handle covered with lead, by the opening of which the acid is allowed to flow through the pipe _b_, to the zinc cuttings, and thus hydrogen gas is produced; _e_ is an opening by which zinc is put into the vessel _c_. The opening, _e_, has a cover furnished with screws and nuts, by which it may be firmly secured; _f_ is an opening by which acid and water are poured into the vessel _a_. When the hydrogen gas is produced, it has to pass through the safety chamber _g_; _h_ is a bent tube or pipe, which conducts the gas from the vessel _c_ to the bottom of the safety chamber, the mouth of the pipe dipping into an inch or two of water in the safety chamber. This water is introduced by the pipe _i_, which is furnished with a stopple. The cock, _k_, cuts off the flow of gas from the vessel _c_, to the safety chamber, _g_. A flexible tube, _m_, is screwed to the top of the safety chamber, and conveys the gas to the working instrument, or jet, in the hands of the solderer. As long as the dilute acid is allowed to flow upon the zinc, hydrogen gas will be produced: the gas will also be formed as long as the cock is open, which allows the gas to issue as it is produced; but as soon as the cock is shut, a small quantity of gas accumulates, and interferes with the further action of the liquid on the zinc. Consequently there is no danger of an explosion, because the production of the gas is never more than is required for working; and when the work ceases, the production of the gas ceases also. When the dilute acid has become saturated with oxide of zinc, and gas ceases to be produced, the discharging pipe is opened, and the liquid withdrawn. By spontaneous evaporation, this liquid furnishes sulphate of zinc (white vitriol), which may be sold at a price which will more than cover the first and daily cost of the apparatus. [Illustration: Fig. 1.] [Illustration: Fig. 2.] We now proceed to describe the part of the apparatus with which the workman operates. In fig. 2, the flexible tube, _m_, is attached to one arm of the forked tube, _o_; the other arm of _o_ is attached to a pipe, _q_, proceeding from a bellows, or other means for supplying air. The solderer may work a bellows with his foot to supply his apparatus with air, or the men in a whole factory may be supplied from a blowing apparatus. A cock, _n_, regulates the supply of gas; _p_ is a cock for regulating the supply of air; _r_ is the pipe or tube in which the gas and air are mixed; _s_, the beak or tool, from which issues the jet of flame, _t_, with which the workman operates.