an apparatus of great utility and elegance, invented by M. Clement. It is known that the absorption or solution of the gases takes place in proportion to the pressure on the absorbing liquid, the extent of surface exposed to the absorbing action, and to the length of time in which it is exposed. If the pressure, however, be very great, the vessels are liable to rupture; and it therefore becomes an important object to strengthen the influence of the other two principles just mentioned, which has been obtained in a very eminent degree by the invention of M. Clement. In this apparatus, which is represented in the annexed diagram, the gas has no pressure to sustain, but the surfaces of its contact are exceedingly multiplied and extended.
The column a is filled with a great number of small bulbs of glass or porcelain, us lower extremity resting in another cylinder b, of greater diameter, in which is a cavity adapted to the reduced diameter of the column, which communicates with two small tubes c, d, the former being employed to introduce the gas, and the latter to discharge the liquid. At e is a reservoir of water, with a conducting pipe f, the supply therefrom being regulated by a cock g. The water, in its passage to the lower part of the column, successively moistens all the small spheres, and being thus impeded in its progress, a very considerable time if occupied in its descent. On the other hand, the gas, as it is introduced, occupying all the vacant interstices, becomes infinitely divided; and therefore as it can only pass through the intermediate spaces very slowly, the duration of the contact is much prolonged, and the absorption promoted. The inventor calculates that the absorbing power of this apparatus is 322 times greater than the ordinary simple vessels used for the purpose. Although M. Clement, in making this comparison, has unquestionably selected the most unfavourable case, it must be admitted that his absorbing cascade possesses great advantages.
To the apparatus thus described, M. Clement adapts another, which he calls " the Productive Cascade," shown in combination in our diagram. It is intended to produce gas for a considerable period of time, and in a more convenient and less expensive manner than by the ordinary methods. Suppose, for example, it is required to prepare oxymuriatic acid or chlorine; a large vessel h, provided with four openings, is filled with oxide of manganese, broken into large pieces; the opening i is by a tube connected to a leaden vessel k, containing common salt and sulphuric acid. By the tube l, a small stream of water is made to flow from the reservoir above, which gradually moistens the whole surface of the pieces of manganese, and permits the muriatic acid gas to attack and dissolve it very easily. The chlorine which is produced passes by the tube n, into the absorbing cascade, while the muriate of manganese is carried off as it forms, by the water, through the tube o, into the reservoir p. By this arrangement, there is no occasion to reduce the manganese to powder, and a much larger quantity may be operated on at the same time, without the operator being under the necessity of frequently renewing the charge of materials, and dismounting his apparatus.