The condenso-purifier shown in the accompanying cut operates as follows: Water is caused to flow over a metallic plate perforated with innumerable holes of from one to three millimeters in diameter, and then, under this disk, which is exactly horizontal, a current of gas is introduced. Under these circumstances the liquid does not traverse the holes in the plate, but is supported by the gas coming in an opposite direction. Provided that the gas has sufficient pressure, it bubbles up through the water and becomes so much the more divided in proportion as the holes are smaller and more numerous.

The gas is washed by traversing the liquid, and freed from the tar and coal-dust carried along with it; while, at the same time, the ammonia that it contains dissolves in the water, and this, too, so much the better the colder the latter is. This apparatus, then, permits of obtaining two results: a mechanical one, consisting in the stoppage of the solid matters, and a chemical one, consisting in the stoppage of the soluble portions, such as ammonia, sulphureted hydrogen, and carbonic acid.



The condenso-purifier consists of three perforated diaphragms, placed one over the other in rectilinear cast-iron boxes. These diaphragms are movable, and slide on projections running round the interior of the boxes. In each of the latter there is an overflow pipe, g, that runs to the box or compartment below, and an unperforated plate, f, that slides over the diaphragm so as to cover or uncover as many of the holes as may be necessary. A stream of common water runs in through the funnel, e, over the upper diaphragm, while the gas enters the apparatus through the pipe, a, and afterward takes the direction shown by the arrows. Reaching the level of the overflow, the water escapes, fills the lower compartment, covers the middle diaphragm, then passes through the second overflow-pipe to cover the lower diaphragm, next runs through the overflow-pipe of the third diaphragm on to the bottom of the purifier, and lastly makes its exit, through a siphon. A pressure gauge, having an inlet for the gas above and below, serves for regulating the pressure absorbed for each diaphragm, and which should vary between 0.01 and 0.012 of a meter.

The effect of this purifier is visible when the operation is performed with an apparatus made externally of glass. The gas is observed to enter in the form of smoke under the first diaphragm, and the water to become discolored and tarry. When the gas traverses the second diaphragm, it is observed to issue from the water entirely colorless, while the latter becomes slightly discolored, and finally, when it traverses the third diaphragm, the water is left perfectly limpid.

Two diaphragms have been found sufficient to completely remove the solid particles carried along by the gas, the third producing only a chemical effect.

This apparatus may replace two of the systems employed in gas works: (1) mechanical condensers, such as the systems of Pelouze & Audouin, and of Servier; and (2) scrubbers of different kinds and coke columns. Nevertheless, it is well to retain the last named, if the gas works have them, but to modify their work.



This purifier should always be placed directly after the condensers, and is to be supplied with a stream of pure water at the rate of 50 liters of water per 1,000 cubic meters of gas. Such water passes only once into the purifier, and issues therefrom sufficiently rich in ammonia to be treated.

If there are coke columns in the works, they are placed after the purifier, filled with wood shavings or well washed gravel, and then supplied with pure cold water in the proportion stated above. The water that flows from the columns passes afterward into the condenso-purifier, where it becomes charged with ammonia, and removes from the gas the tar that the latter has carried along, and then makes its exit and goes to the decanting cistern.

In operating thus, all the remaining ammonia that might have escaped the condenso-purifier is removed, and the result is obtained without pumps or motor, with apparatus that costs but little and does not occupy much space. The advantages that are derived from this, as regards sulphate of ammonia, are important; for, on treating ammoniacal waters with condensers, scarcely more than four to five kilogrammes of the sulphate are obtained per ton of coal distilled, while by washing the gas perfectly with the small quantity of water indicated, four to five kilogrammes more can be got per 1,000 kilogrammes of coal, or a total of eight to ten kilogrammes per ton.

When the gas is not washed sufficiently, almost all of the ammonia condenses in the purifying material.

The pressure absorbed by the condenso purifier is from ten to twelve millimeters per washing-diaphragm. In works that are not provided with an extractor, two diaphragms, or even a single one, are employed when it is desired simply to catch the tar.

The apparatus under consideration was employed in the St. Quentin gas works during the winter of 1881-1882, without giving rise to any obstruction; and, besides, it was found that by its use there might be avoided all choking up of the pipes at the works and the city mains through naphthaline.

In cases of obstruction, it is very easy to take out the perforated diaphragms; this being done by removing the bolts from the piece that holds the register, f, and then removing the diaphragm and putting in another. This operation takes about ten minutes. The advantages of such a mounting of the diaphragms is that it allows the gas manufacturer to employ (and easily change) the number of perforations that he finds best suited to his needs.

These apparatus are constructed for productions of from 1,000 to 100,000 cubic meters of gas per twenty four hours. They have been applied advantageously in the washing of smoke from potassa furnaces, in order to collect the ammonia that escapes from the chimneys. In one of such applications, the quantity of gas and steam washed reached a million cubic meters per twenty-four hours.--Revue Industrielle.