286 



SCIENCE. 



[Vol. XII. No. 306 



the best brands of wrought iron, which contain about 99.5 per cent 

 of iron, against 84 per cent in the manganese steel. 



Electrical Properties. 



This material possesses the peculiar property of being almost 

 entirely non-magnetic. Rinman mentioned in 1773 that manga- 

 nese diminishes, and in the end destroys, the magnetic properties of 

 iron. This was also noticed in some specimens of manganese al- 

 loys made by Mr. David Mushet about 1830. This is especially 

 curious, seeing that iron is present in amounts eight or nine times 

 greater than the manganese itself. An approximate idea of the 

 amount of manganese contained in the steel may be formed by 

 passing a magnet over specimens. As the percentage of manga- 

 nese increases, the magnet's power decreases. Upon reaching about 

 8 per cent, there is no attraction in the bulk, though fine drillings 

 are influenced ; but even this diminishes, as, when 20 per cent is 

 reached, a magnet capable of lifting 30 pounds of ordinary steel or 

 iron will only lift pieces weighing a few milligrams. On this point 

 the material behaves in the same manner either in its forged or 

 cast state, water or oil quenching making practically no difference. 



Some interesting experiments with regard to the physical proper- 

 ties of manganese steel have been made by Sir William Thomson, 

 Mr. Bottomley of Glasgow, and Professor Reinold of the Royal 

 Naval College, Greenwich. Prof. W. F. Barrett, of the Royal Col- 

 lege of Science, Dublin, has also experimented respecting its non- 

 magnetic character and electrical properties. His experiments were 

 carried out upon a sample containing, carbon, .85 per cent ; man- 

 ganese, 13.75 per cent; the wire being drawn to No. 19 British 

 wire gauge. The author first attempted to draw direct from the 

 rods, but with little progress ; the wire, owing to its hardness, 

 breaking into short lengths when being pulled through the wortles. 

 Ordinary annealing was tried, but with no better results. As ex- 

 ceedingly good bending tests have been obtained with bars from 

 the same steel, when heated to a yellow heat and plunged into cold 

 water, the rods were treated in the same manner. These were 

 coiled up, heated to whiteness, and plunged into cold water. The 

 material was then easily drawn ; but, after every reduction through 

 two sizes, its ductility was again lost, and the operation of heating 

 to whiteness and quenching in cold water was again necessary. 

 A specimen has been subjected to white heat no less than five times, 

 and is yet uninjured, as will be seen from the remarkable tensile 

 tests obtained from it by Professor Barrett, viz., no tons per square 

 inch, in its hard state. A similar result was obtained by the man- 

 ager of the wire department at the Barrow Steel Works, the report 

 being " that it would stand any tensile load up to 100 tons per 

 square inch, according to the temper, and the elongation was extraor- 

 dinary." The density, according to Professor Barrett, was 7.81, 

 which is somewhat lower compared with the specific gravity ob- 

 tained at the Hecla laboratory ; viz., 7.83 on the same wire. The 

 electric conductivity was found to be very low; No. 19 British wire 

 gauge wire, .96 millimetre in diameter, having a resistance of 1. 1 12 

 legal ohms per metre, or 75 microhms per cubic centimetre at 15' 

 C. Ordinary iron wire is only 9,800, and German-silver 21,170; so 

 that use might be made of the manganese steel for resistance-coils 

 in electric-lighting. This has since been successfully applied by 

 Dr. E. Hopkinson, in Messrs. Mather & Piatt's electric department. 

 Its high specific resistance, and capacity to stand heating, make it 

 very useful for resistance-boxes. A length of 1,180 yards No. 8 

 British wire gauge (No. 634, manganese 13.95 V^^ cent) was cut 

 into three lengths, coupled parallel, the conductor consisting of 

 three strands No. 8, then coiled into a box 3 feet by 2 feet by 2 feet, 

 and gave a resistance of 6.5 ohms, carrying 80 amp&res without 

 over-heating. It was therefore capable of absorbing 55-horse power. 

 To produce the same resistance with iron wire, 5,000 to 8,000 yards 

 would be required, or, of expensiveGerman-silver wire, 4,780 yards. 

 Professor Barrett also finds that its increase when heated is only 

 .136 per cent for each degree carbon, as against iron .5 per cent. 



In the same way it is a bad conductor of heat. A rough test 

 was made at the Hecla works by putting a bar of this material and 

 one of ordinary wrought iron into a smith's fire. The latter became 

 too hot to handle in about half the time required for the former. 

 From this will be seen the importance of thoroughly ' soaking' this 

 steel when forging it, or the outside only may be heated. 



As regards its non-magnetic properties, a small piece of the No. 

 552 wire was not attracted in the slightest degree by the most pow- 

 erful electro-magnet capable of lifting a ton ; but, suspended by a 

 thread, it behaved like a paramagnetic body. Professor Reinold 

 found that the water-quenched or softened wire acquired slightly 

 more permanent magnetism, but that with both a most sensitive 

 galvanometer-needle was required to show that the material was 

 not copper or other non-magnetic body. The exact amount was 

 determined by Professor Barrett after most careful experiments. 

 In comparing this with ordinary steel, he states that it was like 

 weighing hundredweights and grains on the same balance. The 

 magnetism of ordinary iron being represented by the figure 100,000, 

 manganese steel is 20, and its susceptibility, i.e., the induced mag- 

 netization, is about as low as zinc or other non-magnetic metal. 

 It is somewhat extraordinary to find no sensible attraction exerted 

 on this steel by the most powerful magnetic field that could be ob- 

 tained, this agreeing with Dr. Hopkinson's experiments. If other 

 difficulties can be overcome, this peculiar quality should make it 

 suitable for dynamo bed-plates. Ships built of such steel would 

 have no sensible deviation of the compass. Magnetic influence, 

 while not affecting this material, passes through it, so that a needle 

 placed upon a flat sheet of manganese steel can be readily moved 

 by a magnet placed underneath. The same thing occurs if brass 

 or sheet copper be substituted, but not with ordinary steel or iron. 



Further interesting experiments have also been lately made 

 (September, 1S87) by Profs. J. A. Ewing and William Low. The 

 former concludes his experiments by stating, that, even under mag- 

 netic forces extending to 10,000 C.G.S. units, the resistance which 

 this manganese steel offers to being magnetized suffers no change 

 in any way comparable to that which occurs in wrought iron, cast 

 iron, or ordinary steel, at a very early stage in the magnetizing pro- 

 cess. On the contrary, the permeability is approximately constant 

 under large and small forces, and may be therefore concluded as 

 being only fractionally greater than that of copper, brass, or air. 



MUSICAL BO.XES. 



Music, both as a science and an art, has reached a stage of 

 development so far advanced that further improvement in any 

 department must necessarily seem slow and insignificant. Yet 

 improvements are being made in many directions, seemingly small, 

 but really great enough to demand more than a passing notice. • 



A good instrument is, of course, necessary to the production of 



good music ; but upon even the best of such instruments as the 

 violin or piano, for instance, good music cannot be produced with- 

 out the aid of a good musician. Of musicians, as musicians go, 

 there are plenty, — ordinary every-day musicians, not born to the 

 art, but bred to the business, working at music as a trade, not as an 

 art ; but of good musicians, with a heritage of genius supplemented 

 by a lifetime of labor spent in study, there are few. 



Most people are lovers of good music, or at least of melodious 

 and harmonious sounds. Among these are many who are not 

 musicians themselves, and by whom the services of a good musician 

 are not at all times procurable, nor perhaps desirable. There is- 

 but one among the innumerable instruments in vogue to-day to 

 which such persons can turn, — an instrument in which more or 

 less successful attempts have been made to combine not only the 

 parts to be played upon, perfect of their kind, but also as close an 

 approximation to the executive talents of a musician as mechanical, 

 skill will give. This instrument is known as the musical box, not 

 the crude mechanism of a few decades ago, but the improved in- 

 strument of to-day. 



