This section is from the book "A Treatise On Beverages or The Complete Practical Bottler", by Charles Herman Sulz. Also available from Amazon: A Treatise On Beverages.
An English Machine. - Old Style German Apparatus. - Another German Apparatus.
The annexed two illustrations represent apparatus of this plan. The force pump is only employed to draw from the gasometer and to compress into the cylinder the quantity of gas required to impregnate the water, the agitator being either occasionally or continuously worked, by hand or other power, until the confined gas has attained the proper pressure. The carbonated water is drawn off by the bottler, and the carbonic acid gas remaining in the cylinder is either returned to the gasometer or allowed to escape, at the option of the manufacturer. The contents of the cylinder constitute "a batch," and the same series of operations has to be repeated before another batch is ready for bottling.
It will be seen by comparison with the continuous process machines described afterwards, that this system is very much slower than that now generally adopted.
Opinions will probably always remain divided as to the possibility of producing waters of equal quality by the two processes, but unquestionably the semi-continuous process has the advantage of producing a "beverage almost free of atmospheric air, if the latter is removed through the safety-valve or blow-off cock.
Fig. 55. - Old Style Wooden Carbonating Cylinder.
The semi continuous apparatus of all styles have been in the course of time improved so far as to force with the pump either water or gas, or both at the same time, into the cylinder, thus making it a continuous apparatus, and it is optional with the manufacturer to follow either process - continuous or semi-continuous.
However, some carbonators adhere to the semi-continuous system, and in many factories where the object in view is to obtain carbonated waters of very high quality, rather than to turn out a great quantity in the day, the practice is still followed of charging the condenser with water first, and then pumping in the gas. Where drinks are bottled at a very high pressure this plan is recommended by some makers of great experience.
Fig. 56. - Carbonating Machine with two Copper Cylinders.