The agitator with two large and strong wings Z Z moves in the satu-rator, causing the impregnation of the water. The shaft N of steel receives the motive power from cock-wheel x, and the latter from cock-wheel v and fly-wheel. The shaft revolves in a socket of tinned brass, which is attached and fastened by screws to the saturator, thus being in no connection with the water. To protect the socket from being worn out too quickly the shaft is surrounded with a cover of hardened copper. The end of the socket is closed with a cap screw. The necessary packing in the cylinder at M and N is done with leather, air tight. The leather packing fits closely to the copper cover of the shaft, and serves thus as a soft socket, preventing friction between two metallic surfaces At the end of the shaft in the centre of the saturator are screwed on the two pieces y y which hold the two wings L L. Leather packing here also prevents metallic friction. The contre-screw T secures the connection of the joints, and the agitator may be turned to the right or left. The arrangements of the whole agitator, shaft included, are made in such a way as to secure an easy movement in the cover M and inside of the saturator, and prevent wearing out of the apparatus. The contents of the saturator corresponds with the capacity of the pump, and thus it is possible to impregnate water with carbonic acid in a short time. The safety valve is very sensitive. Let the remaining carbonic acid gas at the finish of an operation escape by raising the screw on safety valve. The water-gauge is protected against accident, the pressure-gauge is easily visible, and both show the operator the course of the operation.

The strength and massiveness of the saturator are a guard against danger of explosion. The apparatus can be easily put together and also taken apart in case of repair.

On top of the saturator is an attachment secured for connecting the safety valve, pressure- and water-gauge. The latter is also connected at screw R with the supply pipe.

The Pressure-gauge indicates on the dial the pressure which the carbonic acid gas exerts in the saturator, and this pressure also indicates or corresponds with the degree of impregnation of the water with carbonic acid gas.

It is constructed on the principle that a spring upon which the air exerts a pressure is able to put a lever in motion, and by this means moves a needle on a dial. These kind of gauges are the most durable, and are used for measuring the pressure of steam on steam-boilers, and in the mineral-water trade to ascertain the pressure of carbonic acid. The arrangement is thus: Space A and B are air tight, separated by the steel spring G. To the lower part of the spring on which the pressure is exerted, is attached a silver-plated copper plate to protect against rusting. On the midst of the spring is fastened a piece in which the steel rod E is fitted in and secured by a screw. As soon as the carbonic acid gas exercises its pressure on the spring, this steel rod lifts the dented triangle and moves by the aid of the cock wheels the needle G G, and indicates thus exactly the pressure upon the spring. The spiral spring H is for the purpose of preventing too free motions of the needle. The scale of the gauge is adjusted by experiment with a quicksilver manometer and pressure pump, and the indications of the quicksilver transferred to the pressure-gauge.

Fig. 112.   Sectional View of Pressure Gauge

Fig. 112. - Sectional View of Pressure Gauge.

At the usual air pressure of the atmosphere the quicksilver in barometer stands at 760 millimeter - that is, the atmosphere or air exerts on the quicksilver such a pressure that it rises to 760 millimeter in the barometer, and this is termed one atmospheric pressure. A weight of 14.7 pounds exerts the same pressure. Consequently: one atmosphere equals a pressure of 14.7 pounds. In Germany and other countries the pressure-gauges are so arranged that the needle indicates at one atmosphere 0, at two atmospheres 1, at three atmospheres 2, etc.; they indicate the super-pressure. In France it is different. There the usual pressure of the atmosphere is indicated with 1 on the gauge. This difference must be taken notice of where either pressure-gauges should be used. In the United States, England and other countries, the pressure-gauges explain the exerted pressure in pounds; the dial plate is graduated to 100 lbs. pressure per square inch. One atmosphere, or the atmospheric pressure of 14.7 pounds, is not indicated, only the super-pressure, as in Germany.

The following table shows comparatively the indications on these three pressure-gauges:

Atmospheres.

Germany.

France.

U. S. and England.

Atmospheres.

Pounds.

1

atmosphere ..

0

1

0

2

atmospheres ..

1

2

15

3

"

2

3

29

4

"

3 .

4

44

5

"

4

5

59

6

"

5

6

74

7

"

6

7

88

8

"

7

8

103

9

"

8

9

118

10

"

9

10

132

11

"

10

11

147

12

"

11

12

162

13

"

12

13

176

14

"

13

14

191

15

"

14

15

206

The pressure-gauges in the United States indicate the actual pressure exerted by the carbonic acid gas. The safety valve is adjusted with an alarm whistle, and consists of two parts; the upper one serves as signal bell, and the lower part is connected with the water-gauge at T. A small opening from saturator to the lower part of the safety valve allows the gas a free passage. The safety valve is kept closed by the scale K as long as the pressure in saturator has not exerted the normal capacity. Lever e which is movable at f, transfers the pressure of scale K upon the rod of the safety valve. At the other end is the connection with the scale K, the pressure of which may be regulated to suit by screw I. Cap g of the protecting case of the scale is movable, and allows the examination of the scale whenever necessary. The working of the valve with the signal whistle is easily to be understood; if the pressure of the gas exerts the quantity of pounds or atmospheres required, it overcomes the resistance exerted by the scale and lever upon the rod of safety valve, and gas escapes until the pressure is reduced to the required amount. In escaping the gas sounds the whistle. That this safety valve is always in good condition ought to be frequently ascertained. The water-gauge H consists of a tube of white glass, framed in brass, and thus protected against accident. The screw Z presses the glass tube against their rubber packing and thus makes a tight connection. The water-gauge is by pipe v with the supply pipe, by extension m with the saturator connected, and as both communicate the pressure is equalized. A look on this water-gauge shows the corresponding increase of the saturator.

Fig. 113.   Another Plan of French Apparatus

Fig. 113. - Another Plan of French Apparatus.

Another style of French apparatus of the continuous plan is represented by the above illustration. This continuous apparatus is based m the same principle as that described on the foregoing pages. The bronze saturator, cast in single piece, is of different shape. The material and arrangement is principally the same.