There is a third system, which impregnates the water chemically by the aid of the expansive power of the generated carbonic acid gas by the pressure produced in the generator without the aid of a pump or gasometer. This system is much used in America, Germany, France, Russia, and is also adopted in England, and it is called the intermittent plan.

In the United States a set of apparatus after this plan, but with two generators, is called a "continuous apparatus, American plan "

The idea is to charge one generator while the other one is in operation, in fact to enable a continuous operating, and which is thus practically achieved; but if one generator is attached, the operation has to be interrupted after the generator is exhausted and fresh material must be supplied. The pumps attached to the American apparatus are for injecting the fountains with water when they are exhausted, to prevent waste of gas and force the water against the remaining gas pressure, which is then impregnated by means of agitation.

On the same principles is based the French intermittent apparatus with pump, called "system Ozouf".

The generators on the American apparatus are either horizontal and acid-feeding or vertical and carbonate-feeding; the former being more generally in use.

The fountains or cylinders are either stationary or portable.

The semi-continuous carbonating apparatus of the "eneva" system is employed especially where carefully prepared mineral waters and other delicate beverages under exclusion of atmospheric air need be manufactured. They are usually so far improved as to work them also continuously if desired.

The continuous apparatus, Bramah system, is much used in large bottling establishments advantageously where a large and uniform production is required, and motive power is available.

The American apparatus, intermittent system, can be economically employed in small establishments. The larger sets, so-called continuous, American plan, are practically for large establishments where the business fluctuates considerably and the requirements in winter are much less than in summer.

Liquid Carbonic Acid System

The latest or fifth system introduced to the trade we might term the "liquid carbonic acid system" It can be employed in either system; the supply taken from one, two or more carbonic acid cylinders instead of the generator, and discharged into the gasometer or direct to the fountain or cylinders, permitting a continuous operation.

Following in this Part we shall describe the construction of the apparatus made after the different systems, mention the latest improvements, and arrange them systematically to make the reader conversant with the principal makes of carbonating apparatus of Europe and the United States.