The general judgment of those best informed on the subject is, that the credit for the invention in a commercial practical form, has been rightly bestowed on Professor Bell. In any event, the originality of Bell's work, and the marvelous character of the results that flowed from it are not affected in any degree by experiments which the scientific world either knew nothing of or had forgotten all about. No mere legal technicalities will ever convince men that the invention of the telephone was not a stroke of genius, and they will be inclined also to honor most the man who actually put the marvel into their hand. We need not, in fairness, ascribe less praise to Philip Reis, or Elisha Gray, or Professor Dolbear; but we cannot quarrel with the public, if it chooses to single out Professor Bell for the highest homage.

All three of the American inventors mentioned have displayed inventive capacity in other ways, Mr. Gray, especially, being a fertile inventor in many different fields.

Charles F. Brush has done for arc lighting what Edison did for incandescent. It grew under his hands into a usable system of light distribution which is now a necessity. Brush also made early improvements in storage batteries, but his best work has been done in connection with the arc lamp and the dynamo-electric machine. The high resistance shunt, if not absolutely introduced into the arts by him, is, at least, his, in every proper sense, so far as it applies to the purpose of arc lighting. And in the same way the universally used means for controlling the feed of the positive carbon, are his contribution to the are lamp. Mr. Brush gave his name many years ago to one of the most successful electrical corporations in the country, the Brush Electric company, of Cleveland, Ohio.

The prominence of Edward Weston, for many years as electrician of the United States Electric Lighting company, would call for notice here, even if his successes in improving the electric light and the dynamo-electric machine did not themselves merit it. But his prominence, as is usually the case where large business interests are involved, has been fairly and fully deserved. The Weston dynamo is one of the standard machines for generating the electric current.

In view of the number of electric railroads in this country in actual operation or in process of construction, it seems hardly credible that the first experimental road since the dynamo gave the experiment significance and promise was constructed so short a time ago. This was the Edison road at Menlo Park. A year later, Mr. Stephen D. Field had a road in successful operation at Stockbridge, Mass., and, an interference being carried through in the patent office to decide the rival claims of the two inventors under their applications for patents, it was discovered that the title to priority in the invention belonged to Field. The latter inventor afterwards put up a railway in the main exposition building at Chicago in 1883. On this railway were carried in the two weeks of its service more than twenty five thousand passengers from whom, for the first time on an electric road, a small fare was collected. Mr. Field, conjointly with Mr. Rudolph Eickemeyer, has recently made what appears to be a valuable improvement in electric cars, which consists in coupling a slow speed motor directly upon the car axles, all gearing being dispensed with. In 1883, Mr. Leo Daft conducted several successful experiments in electric railroading, and in 1885 he built at Baltimore a road which carried the regular traffic of the Hampden branch of the Baltimore Union Passenger Railway company for nearly five years. Prior to this time-in August, 1884-Messrs. Edward M. Bentley and Walter H. Knight had built a conduit electric railway on the tracks of the East Cleveland Horse Railway company at Cleveland, Ohio.

Early in 1885, John C. Henry built at Kansas City the first overhead wire electric railway.

Another pioneer inventor in the line of electric locomotion is Mr. Charles J. Van Depoele. His first road was laid in Chicago early in 1883, and he exhibited another at the exposition later in the same year. Since then many roads have been constructed under his patents. It is probably only just to Mr. Van Depoele to say that he is entitled to more credit than any other man for the exploitation of electricity as a motive power. He has devised ingenious improvements in electric drill machinery which for the first time make it practically successful.

THE DEVELOPMENT OF INDUSTRIAL

ELECTRO-CHEMISTRY.

BY E. F. ROEBER.

[Edward F. Roeber is one of the best known electro-chemists in the world. The application of electricity to chemistry and the chemistry of electricity have been his study for many years and he has written several articles on the art in whose development he has had such a prominent part. The article below was written on the occasion of the quarter-centennial of the Electrical World and is here published by special arrangement.] Copyright 1904 by McGraw Publishing Company

While of all branches of electrical engineering electrochemistry has been the last one to achieve commercial successes on a large scale and may justly be considered to be still in the first phase of its industrial development, yet its fundamental principles were long exactly known (electrolytic action -Faraday's law, electro-thermic action-Joulean heat). Moreover, at the beginning of the nineteenth century the very first experimental applications of the newly discovered electric current were of an electrochemical nature. Shortly after the primary battery had been invented by Volta, Nicholson and Carlisle succeeded in decomposing water by electrolysis, and in 1807 Sir Humphrey Davy delivered his famous lecture on some chemical agencies of electricity. Yet (to quote from the recent Bradley patent decision) "Davy's experiments were permitted to lie dormant during seventy six years of intense activity," and in general the progress in the development of industrial electrochemistry and electrometallurgy was extremely slow for a long period. In fact, thirty one years ago, when the first issue of this journal appeared, there did not exist any electrochemical industries, with the single exceptions of electroplating and primary battery manufacture.

It is now not difficult to see what held the development of industrial electrochemistry back. In nearly all electrochemical and electrometallurgical processes the cost of the electric power is a large fraction of the total cost of operation, often 25 per cent or more, and even up to 90 per cent. Cheap electric power is, therefore, the fundamental requirement for

the economical working of an electrochemical process, in exactly the same way as it is for electric lighting, traction, and power purposes in general. Before the advent of the dynamo, the primary battery was the only available source of the electric current, if we except a limited use of the thermopile, and its limitations are obvious. The operation of a primary cell meant and still means essentially oxidation of zinc. When zinc changes from the metallic state into bivalent ions, 1.22 grams are oxidized, according to Faraday's law, for every ampère hour; we know that, with all possible combinations of zinc with other materials in a primary battery, we never get much more than 2 volts, and if we assume the useful e.m.f. to be 1 volt (which is very fair for such an estimate), then every kilowatt hour produced means the oxidation of 1.22 kg (or 24 pounds) of zinc. This is the theoretical value which really represents a minimum of actual consumption; moreover, it does not include the cost of the other materials in the cell, nor the cost of construction and attendance; but it is sufficient to indicate the inherent limitations of the zinc primary battery.

So long as primary cells were the only commercial sources of electric current, the applications of electrical engineering were thus necessarily restricted to those cases in which a very small amount of power only is required. That is especially the case in telegraphy, and, in the field of electrochemistry, in those cases of electroplating in which a soluble anode is used of the same metal which is to be deposited upon the cathode. Here the voltage required at the terminals of the plating bath is consumed in overcoming the internal resistance only, which may be made small, and, therefore, the power may also be insignificant.

It is quite natural that after the dynamo had made its commercial appearance, electric lighting and the mechanical applications of electricity, such as traction and power transmission and distribution, first attracted the inventive talents of electrical engineers. Nevertheless, as we were reminded by the institute dinner to Mr. Edison, the incandescent lamp is now only 26 years old. It is, therefore, not surprising that our electrochemical industries are still young, since their

development depended rather on chemists and metallurgists, who were attracted by the possibilities of the application of the electric current which had proven to be such a manageable and thoroughly reliable agent in other fields of engineering.

The following sketch naturally does not aim at completeness, and no attempt will be made to give details of processes. The object is rather to bring out some general principles which have manifested themselves all along during the development of the electrochemical industries-leitmotives, to borrow a word from Wagner's operas. At the same time, we will try to arrive at a convenient classification of the whole subject. One general subdivision of all electrochemical processes and phenomena into two large classes offers itself. In the first class electrical energy is consumed to produce chemical effects, while in the second class chemical energy is changed into electrical energy. Thus, the second class comprises the whole field of primary cells and storage batteries, while in the first class we have all those more or less novel processes which are now mostly thought of when one speaks simply of electrochemical and electrometallurgical industries.

Chemical effects may be produced by means of electrical energies in various ways. We can change the electrical energy into heat, which is then consumed in producing the desired chemical effect; or we can change electrical energy into chemical energy directly by electrolysis; or we may use a combination of both methods; finally, a fourth method of producing chemical effects is by passing an electric discharge through gases. Before giving a cursory review of applications of these various principles, a general remark should be made on the nature of chemicals produced by such methods.

Many of these processes consume a considerable amount of electrical energy. In the discussion of furnace processes from the ordinary chemical point of view, we may, of course, say that the energy is expended to produce a certain temperature which is required to start the process. This, however, does not tell the whole story. We expend a certain amount of electrical energy which is lost while the process is going on. What becomes of it? If the process is conducted under fairly economical conditions most of the electrical energy is