Fig. 218 represents an acid feeder, already shown in illustration on another page. The method of supplying sulphuric acid is by pouring it in at the leaden funnel. When the pipe becomes charged with sufficient acid it forms a stoppage which the gas cannot pass, as the pipe always remains filled to the height of the bent part or inlet on top of generator; whatever amount of acid is afterwards poured in at the funnel will be the exact amount that goes into the generator. If the pipe leading from the generator becomes clogged up and will not allow the gas to pass freely, instead of straining the generator or the pipe of gasometer the acid is forced up the syphon pipe, strikes against the top of the box, and afterwards finds its level, when the undue pressure has been relieved from the generator, by the gas flowing into the gasometer. The pipe is generally of lead, but very often strong glass tubes are also used.

This style of automatic acid feeder is frequently attached to continuous apparatus constructed after the English, plan.

Fig. 218.   English Acid Feeder

Fig. 218. - English Acid Feeder.

Fig. 219 represents a glass syphon which is in some instances used to empty the acid from the tank or carboy. Once filled, by lowering or raising it the flow of acid can be regulated.

Fig. 219.   Acid Syphon

Fig. 219. - Acid Syphon.

As shown in Fig. 220 this kind of acid feeder is employed on apparatus of German manufacture. It is a "Woulf bottle," with registering tube a, connected by cock and feeding tube b with the generator, and with equalizing pipe c, acid inlet d. It is a practical arrangement for low pressure apparatus.

Fig. 220.   Registering Glass Acid Feeder

Fig. 220. - Registering Glass Acid Feeder.