49 s 



NATURE 



[Sept. 20, 1888 



and innumerable articles of daily use, are being rendered not only 

 more durable but more beautiful. 



The electro-deposition of iron, as devised by Jacobi and Klein, 

 in the hands of Prof. Roberts- Austen, F.R.S., is giving very 

 interesting results. The dies for the coins which were struck at our 

 Mint on the occasion of the Jubilee of the Queen were modelled 

 in plaster, reproduced in intaglio by the electro- deposition of 

 copper, and on these copper moulds hard excellent iron in layers 

 of nearly y T of an inch was deposited. 



The exact processes of measurement, which have led to such 

 vast improvement in our telegraphic systems, have scarcely yet 

 penetrated into this field of electrical industry, and little is known 

 at present of the exact relations of current and electromotive 

 force with respect to surfaces of contact, rate of deposit, and 

 resistance of liquids. Captain Sankey, R.E., of the Ordnance 

 Survey Department, has done some useful work in this direction. 



The extraction of metals from their ores by deposition has 

 received wide application in the case of copper. In 1871, 

 Elkington proposed to precipitate copper electrolytically from 

 the fused sulphide of c *pper and iron known to the copper 

 smelter as "regulus." Thin copper plates were arranged to 

 receive the deposited copper, while the foreign metals, including 

 gold and silver, fell to the bottom of the solution, the process 

 bein^ specially applicable, it was supposed, to regulus containing 

 small quantities of the precious metals. 



The electrical purification of copper from impure "blister 

 copper" or " blade copper" has also made great progress, and 

 special dynamos are now made which will, with an expenditure 

 of 100 horse-power, precipitate 18 tons of copper per week. 

 The impure metal is made to form the anode in a bath of 

 sulphate of copper, the metal being deposited in the pure form 

 on a thin copper cathode. 



It was not very long ago considered very economical to 

 absorb o 85 horse-power in depositing 1 pound of copper per 

 hour, but now the same work can be done with 0*3 horse- 

 power. Mr. Parker, of Wolverhampton, has done good work 

 in this direction, and his dynamos in Messrs. Bjlton's works have 

 revolutionized this process of purification. 



Both at Swansea and Widnes, immense quantities of copper, 

 in spite of the restrictive operations of the Copper Syndicate, 

 are being produced by electro-deposition. Copper steam- 

 pipes for boilers are now being built up of great firmness, 

 fine texture, and considerable strength, by Mr. Elmore, at 

 Cockermouth, by electro-deposition on a rotating mandril in a 

 tank of sulphate of copper. By this process one ton of copper 

 requires only a little more than one ton of coal to raise the 

 requisite steam to complete the operation. 



It ha-; been shown that the electrolytic separation of silver 

 from gold by similar methods is perfectly practicable. The 

 value of the material to be dealt with may be gathered from the 

 fact, communicated to the Gold and Silver Commission now 

 sitting, that nearly 90,000,000 ounces of silver are annually 

 produced, and the greater portion of this amount contains 

 sufficient gold to render refining remunerative. Although the 

 old acid process of "parting " gold and silver remains practically 

 undisturbed, there seems no reason to doubt that in the future 

 electricity will render us good service in this direction, as it has 

 already in the purification of copper. 



There is not much actual progress to report in the extraction 

 of gold from its ores by electrical agency. The conversion of 

 gold into chloride of gold by the direct, or indirect, action of 

 chlorine is employed on a very large scale in [Grass Valley] 

 California and elsewhere. This fact has led to well-directed 

 efforts to obtain, by electrolytic action, chlorine which should 

 attack finely-divided gold suspended (with the crushed ore) in 

 the solution from which the chlorine was generated, the gold, so 

 converted into soluble chloride, then being deposited on a 

 cathode. The process would seem to be hopeful, but is not as 

 yet a serious rival to the ordinary chlorination method. 



In the amalgamation of gold ores much is expected from the 

 possibility of keeping clean, by the aid of hydrogen set free by 

 the electric current, the surfaces of amalgamated plates. 



It is well known that the late Sir W. Siemens considered 

 that the electric arc might render good service in the fusion of 

 metals with high melting-points, and he actually succeeded in 

 melting 96 ounces of platinum in ten minutes with his electrical 

 furnace. The experiments were interrupted by his untimely 

 death ; but in the hands of Messrs. Cowles the electric arc pro- 

 duced by 5000 amperes and 500 horse-power is being employed 

 on a very large scale for the isolation of aluminium (from 



corundum), which is immediately alloyed {in situ) with copper 

 or iron, in the presence of which it is separated. 



The heating power of large currents has been used by Elihu 

 Thomson in the United States, and by Bernardos in Russia, to 

 weld metals, and it is said to weld steel without affecting its 

 hardness. It has even been proposed to wekl together in one 

 continuous metallic mass the rails of our railways, so as to 

 dispense entirely with joints. 



The production of chlorine for bleaching and of iodine for 

 pharmaceutical purposes, the economical production of oxygen, 

 are also processes now dependent on the electrolytic effect of the 

 electric current. 



It is almost impossible to enumerate the various general 

 purposes to which electricity is applied to minister to our wants 

 and to add to our comforts. Everyone appreciates the silent 

 efficiency of the trembling electric bell, while all will sooner or later 

 derive comfort from the perennially self-winding electric clock. 

 Correct mean time is distributed throughout the length and 

 breadth of the land by currents derived from Greenwich 

 Observatory. Warehouses and shops are fitted with automatic 

 contact pieces, which, on any undue increase of temperature due 

 to fire, create an alarm in the nearest fire-station ; and at the 

 corner of most streets a post is found with a face of glass, which 

 on being broken enables the passer-by or the watchful and active 

 policeman to call a fire-engine to the exact spot of danger. Our 

 sewers are likely to find in its active chemical agency a power to 

 neutralize offensive gases, and to purify poisonous and dangerous 

 fluids. The germs of diseases are attacked and destroyed in 

 their very lairs. The physician an 1 the surgeon trust to it to 

 alleviate pain, to cure disease, to effect organic changes beyond 

 the reach of drugs. The photographer finds in the brilliant 

 rays of the arc lamp a miniature sun which enables him to pursue 

 his lucrative business at ni> ht, or during the dark and dismal 

 hours of a black November fog in Eondon. 



We learn from the instructive and interesting advertising 

 columns of our newspaper that " electricity is life," and we 

 may perhaps read in the more historical portion of the same 

 paper that by a recent decision of the New York Parliament, 

 " electricity is death." It is proposed to replace hanging by the 

 more painless and sudden application of a powerful electrical 

 charge ; but those who have assisted at this hasty legislation 

 would have done well to have assured themselves of the 

 practical efficacy of the proposed process. I have seen the 

 difficulty of killing even a rabbit with the most powerful induc- 

 tion coil ever made, and I know those who escaped and 

 recovered from the stroke of a lightning discharge. 



The fact that the energy of a current of electricity, either 

 when it flashes across an air space, or when it is forced through 

 high resistance, assumes the form of heat of very high tempera- 

 ture led early to its employment for firing charges of gunpowder ; 

 and for many civil, military, and naval purposes it has become 

 an invaluable and essential agent. Wrecks like that of the Royal 

 George at Spithead were blown up and destroyed ; the faces of 

 cliffs and quarries are thrown down ; the galleries of mines and 

 tunnels are excavated ; obstructions to navigation like the 

 famous Hell Gate, near New York, have been removed ; time- 

 guns to distribute correct time are fired by currents from 

 Greenwich at 1 p.m. In the operations of war, both for attack 

 and defence, submarine mining has become the most important 

 branch of the profession of a soldier and a sailor. Big guns, 

 whether singly or in broadside, are fired ; and torpedoes, when 

 an enemy's ship unwittingly is placed over them, are exploded 

 by currents of electricity. 



An immense amount of research has been devoted to design 

 the best form of fuse, and the best form of generator of electricity 

 to use to explode them. Gun tubes for firing consist of a short 

 piece of very fine wire embedded in some easily fusible com- 

 pound, while the best form of fuse is that known as the Abel 

 fuse, which is composed of a small, compact mass of copper 

 phosphide, copper sulphide, and potassium chlorate. The prac- 

 tice in the use of generators is very various. Some, like the 

 Austrians, lean to the high-tension effects of static electricity ; 

 others prefer magneto-machines ; others use the dynamo ; while 

 we in England cling with much fondness to the trustworthy 

 battery. Since the electric light has also become such a valuable 

 adjunct to war purposes, it is probable that secondary batteries 

 will become of immense service. The strong inductive effects of 

 atmospheric electricity are a source of great danger. Many 

 accidental explosions of fuses have occurred. An experimental 

 cable with a fuse at one end was laid below low water mark 



