A represents the lead-lined cistern. It may be made any size to suit requirements, say sufficient to hold two or three carboys of acid, which may be diluted with an equal quantity of water when in the cistern where whiting is used. The acid cisterns are made with a slanting shoot at one end, so that in pouring in the acid it will not splash up, but run quietly down. Every part must be covered with sheet lead, the joints of which are made by the autogenous process, so that no action takes place to destroy any part. At the outlet pipe leading to the acid tap is a large movable strainer to prevent straw or dirt from passing.

B represents acid measure box, all lead; this is filled with the requisite quantity of diluted sulphuric acid from the tap above, according to the size of generator and quantity of carbonate used, the height being shown by the glass gauge in front. The lower tap is turned as required to raise the gasometer. This system is very handy where the generator is driven by steam, as the lower tap may then be left running very gently, according to the speed of the soda-water machine.

Another English plan are the machines represented and described as follows: They are manufactured by Hay ward Tyler & Co., London, Eng.

This machine (Fig. 74) is on the continuous principle, and, like Bramah's machine, it has a pump with a solid piston working from below.

On each side of the pump are placed suction valves, one for gas, and the other for water, in suitable valve pieces with regulating cocks. The outlet or delivery valve is on the top of the pump, in a gun-metal chamber, with a pipe attached to convey the gas and water to the globe. The latter is mounted on a suitable bracket, on the top of which are bearings for the beam gudgeon.

Fig. 73.   Arrangement for Measuring Sulphuric Acid

Fig. 73. - Arrangement for Measuring Sulphuric Acid.

Motion is given to the pump piston, up and down, by the oscillation of the beam, one end of which is connected by a rod with the crank, and the other to the side rods attached to the guide frame of the piston. The workmanship of the beam, rods, joints, etc., is fine engine work. The bottling cock is at one end of the frame, and the crank shaft at the other. This arrangement admits of the use of two handles, one on each end of the crank shaft, so that where hand power only can be applied, two men may work the machine. The construction of this machine is fully elucidated by the aid of the engraving. A is the gas generator; B the acid bottle; C is the water tub into which the gas-holder, D, descends; E is the solution-pan connected with the pump, F, by the copper pipe, H; I is the pipe which conveys the gas from the holder to the pump; K is the pipe for conveying the mixed gas and water from the outlet valve of the pump to the condenser, 0; P is the safety valve of the condenser; N is a train of wheels for communicating motion to the agitator within the globe; L is the discharge pipe; M the bottling tap; and G the pressure-gauge. The general description of the parts is given by the manufacturers, as follows:

"A. The gas generator is a strong cylindrical leaden vessel, in which the carbonic acid gas is generated by the action of sulphuric acid upon the carbonate. The carbonate, mixed with water, is put into the generator through a large aperture at the top, which is afterwards closed by a strong cap and screw. Inside the generator there is an agitator or rouser formed of copper, with a copper rod passing through a stuffing-box at top by means of a handle on the rod; this agitator can be worked as required in order to stir up the deposit of the carbonate. At the bottom of the generator there is an outlet for the spent carbonate - sulphate of lime. The gas, as it is generated, passes into the gasometer through a bent pipe, one end of which opens into the top of the generator, and the other joins a pipe entering the gasometer. The generators are all made of very thick and strong lead, and the workmanship is of the best quality. The fittings are also very strong and heavy. As the outlet of the gas is quite free there is no danger of an explosion, and no copper casing is required.

Fig. 74.   Continuous (Beam Action) Apparatus

Fig. 74. - Continuous (Beam-Action) Apparatus.

"B. The acid bottle, which is also made of lead, cast in one piece, is attached to the generator by a swivel joint. The sulphuric acid is introduced through an aperture at the top of the bottle, while the latter is in the position shown in the engraving. The aperture being then closed by a cap and screw, the acid is let into the generator by occasionally tilting the bottle on one side or the other, and whenever this operation is performed a turn is given to the rouser in order to mix the acid with the whiting. This arrangement, while being perhaps the simplest that could possibly be devised, has, at the same time, great advantages, as it dispenses with any necessity for valves or cocks to admit the sulphuric acid. It is needless to say that with such a corrosive material it is very troublesome to have to keep valves tight. The generator may also be supplied by mi extra acid box. This plan prevents overcharge of acid, as it is admitted by an earthenware tap into the acid box.

"C.D. The gasometer is made of copper, thoroughly tinned inside with pure English tin. It works up and down in water contained in a strong iron-bound oak tub, in which are fixed two copper pipes - one for the admission of the gas from the generator, and the other for conveying it to the soda-water pump. Both these pipes pass through the water above its surface, but the extremity of the former one is bent downwards for some distance into the water, so that the gas, after its liberation from the generator, may be washed and purified. A small cock, fixed to the top of the gasometer, serves to let off the atmospheric air at the first filling. The water in the gasometer tub should be frequently changed to prevent any impurity getting mixed with the gas. We recommend in addition an extra washing apparatus to purify the gas, and it should be borne in mind that if proper care is taken in washing the gas, it is, in the opinion of the best chemists, impossible for any contamination to get into the water from the generator.