by order of the imperial postal department, apparatus of various systems and constructions were subjected to tests, and the apparatus we are speaking of showed the favorable results just mentioned.  This microphone has overcome in particular the difficulties connected with the using of combined lines above and below ground, and with the aid of it the excellent telephonic communication is carried on in Berlin, in which city the telephone net is most extensive and complicated.  At the same time this microphone transmits the sound over long distances (up to 200 kilom. even) in the most satisfactory manner.  Another peculiar advantage of this construction is that it exercises a very small inductive effect on cables and free lines, and consequently the simultaneous speaking on parallel lines causes but little disturbance.

After repeated trials made by the German imperial postal department with the microphones constructed by Messrs. Mix and Genest, these apparatus have been introduced in the place of the telephones and Bell-Blake microphones hitherto used in the telephone service.  At present we understand there are about 8,000 of these apparatus in use.

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ELECTROLYSIS AND REFINING OF SUGAR.

Mr. G. Fahrig, of Eccles, Lancashire, has invented a new process of refining sugar through electrolysis.  The brown sugar is decolorized by means of ozone produced by electric currents of high tension from a dynamo.  The electrodes consist of metal grills covered with platinum or some other inoxidizable metal, and are placed in a vat with the intervention of perforated earthenware plates.  After being ground and dried in hot air, the crude sugar is placed between the plate and the grills, and the discharges passing between the electrodes produce ozone, which separates the sugar from the coloring matter.  To purify the sugar still further, Mr. Fahrig dries it and places it in another vat, with carbon or platinum conducting plates separated by a porous partition.  The sugar is placed on one side of this partition, and water circulates on the other side.

The current from a dynamo of feeble tension is sent through the vat between the plates.  The water carries along the impurities separated by the current, and the sugar is further whitened and refined.

[Illustration]

The accompanying figure shows a series of four vats arranged one above another, in order to permit the water to circulate.  Here i and h represent the plates connected with the poles of the dynamo through the conductors, f and g; m represents the porous partition; L, the spaces filled with sugar; and l, the compartments in which the water circulates.—­La Lumiere Electrique.

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[THE ELECTRICIAN.]

A CURRENT METER.