212 



NA TURE 



[December 29, 189S 



surrounded by extensive morasses. The ore occurs in bed-like 

 masses in porphyries of varying character and coniposilion. 

 The total length of the Kiirunavaara ore body is 15,500 feet. 

 The width is u.sually 330 feet, but in one place it is as much as 

 840 feet. The dip varies from 45' to 60". It is estimated 

 that the quantity of ore available above the level of the lake 

 at Kiirunavaara is 215,000,000 tons, and at Luossavaara 

 18,000,000 tons. 



The Kiirunavaara ores differ widely from most Swedish ores. 

 They are unusually hard and compact, and remarkably free 

 from all foreign minerals except apatite. That mineral is, how- 

 ever, exceedingly abundant. Analyses show that ores occur 

 with less than 0'05 per cent, and from 0'05 to O'l per cent, of 

 phosphorus in such quantities that they can be mined separately. 

 The bulk of the ore, however, contains i to 4 per cent, of 

 phosphorus. The percentage of sulphur is usually o'05, and 

 sometimes less than 002. Titanium varies from 032 to 095 

 per cent., and manganese does not exceed 032 per cent. The 

 great bulk of the Luossavaara ore is comparatively low in 

 phosphorus, and much of it appears to be well adapted for the 

 acid Kessemer process. 



No serious attempt was made to work these deposits before 

 1880, when a concession was granted for the construction of a 

 railway from Lule.i to the Ofoten fjord ; but the concession 

 was withdrawn after the railway had been completed from 

 Lulea to the iron mines at Gellivare. This year, however, the 

 Swedish parliament authorised the construction of a railway 

 from Gellivare, past the Kiirunavaara and Luossavaara deposits, 

 to the Norwegian frontier ; and the Norwegian parliament has 

 authorised its being continued to Victoria Harbour, on the 

 Ofoten Ijord, a port free from ice throughout the year. The 

 distances from the iron ore deposits along the projected line of 

 railway are — to Gellivare, 63 miles ; to LuleA, 182 miles ; to 

 the Norwegian frontier, 79 miles ; and to Victoria Harbour, 

 120 miles. Within a short period these vast supplies of iron 

 ore will thus be rendered available, and British ironmasters 

 will have within easy reach sufficient ore to last for many 

 generations to come. 



ELECTRICAL STAGE APPLIANCES. 

 'T'nE proposed application of electrical power for mounting 

 ■*■ plays at Drury Lane, on the lines advocated by Mr. Edwin O. 

 Sachs, has now taken a tangible form in the completion of the 

 first section of the stage installation in time for the impending 

 pantomime. 



Mr. Sach's present work refers principally to the stage floor 

 and its movability in sections above and below the footlights. 

 The total area now already movable by mechanical power 

 exceeds 1200 square feet. 



The electrical appliances just completed take the form of 

 so-called "bridges," each working independently. Each in- 

 dividual section measures 40 feet by 7 feet, and weighs about 

 6 tons, of which about 4 tons are counterbalanced. They can 

 travel about 20 feet vertically. 



The motive power is from the ordinary electric supply mains 

 over a four-pole motor, developing 7A horse-power at 520 revo- 

 lutions per minute. The "bridges" are suspended from cables, 

 and these, working over the motor, allow the former to be raised 

 with the necessary live load at rates varying from 6 feet to 20 feel 

 per minute. 



Every possible safeguard has been taken against accident, the 

 " bridges " themselves being so constructed that in the event of 

 derangement of current the appliances can be worked by hand 

 gear. Automatic switches are provided so as not to be entirely 

 dependent on the attendants, and automatic catches will work 

 in case of rope-breaking. Special locking-gear has been installed 

 to hold the " bridges " stationary at certain points, such as 

 stage level, and a very large factor of safely has been allowed 

 in apportioning the strengths and weights in the various 

 parts of the mechanism, having special regard to the ever- 

 increasing scenic requirements under Mr. Arthur Collins's able 

 management. 



As regards the economic aspect of the electrical installation, 

 the initial outlay on the system adopted is about half that of 

 continental hydraulic work. The maintenance is minimal, 

 whilst the actual working only costs a few pence per performance. 

 The saving in manual labour on the stage is very considerable, 

 whilst the h)giene of the theatre is materially raised by the 

 absence of woodwork. 



NO. 1522, VOL. 59] 



METALLIC ALLOYS AND THE THEORY 

 OF SOLUTION} 

 'T'HE term alloy in its technical sense is used to indicate a 

 solid mixture of two or more metals. The earlier investi- 

 gators in this field, such as Matthiesen, Richie and many 

 others, worked mainly with solid alloys, and they endeavoured 

 to investigate the change in properties of the alloy, such as 

 conductivity for heat and electricity, malleability, ductility and 

 the like, with successive small changes in composition. 



This method, although well adapted to bring out properties 

 of alloys suitable for use in the art.s, has not till recently shed 

 much light on the real constitution of this interesting group of 

 suljstances. Chemists have neglected the subject because the 

 ordinary processes by which they attack problems fail them 

 when dealing with alloys, on account of their opacity, want o( 

 volatility and power of being separated from one another by 

 crystallisation. Another difficulty ari.ses from the fact that the 

 resulting alloy has usually the same colour as the metals from 

 which it is produced, except in a few cases, such as the rich 

 purple alloy of gold and aluminium investigated by Prof. 

 Roberts-Austen, and the alloy of zinc and silver noticed by 

 Matthiesen and investigated by Neville and Heycock, which 

 has the property of taking a superficial rose tint when heated 

 and suddenly cooled. 



During the past twelve years considerable advance has been 

 made in the study of alloys by investigating some of their 

 properties whilst in the liquid state, such as the temperature at 

 which solidification commences ; it is convenient to term this 

 temperature the freezing point. Le Chatelier, Roberts-.\usten, 

 Neville, myself and others have all worked in this way. The 

 result of this work may be very briefly stated as follows. 



Solutions of metals in one another obey the same laws that 

 regulate the behaviour of solutions of such substances as sugar in 

 water. For example, if we take solutions of sugar of different 

 concentrations, but not exceeding 3 or 4 per cent., we find that 

 within these limits the lowering of the freezing point is nearly 

 proportional to the concentration. E.\actly in the .same way, if 

 we add to a quantity of molten sodium (freezing point 97° C. ) 

 some gold, we find the gold dissolves much in the same way 

 that sugar dissolves in water. On determining the freezing 

 point of the alloy we find that it is lowered in direct proportion 

 to the weight of gold added, notwithstanding the fact that pure 

 gold by itself melts at a temperature of 1060° C. It is remark- 

 able that the eflect of increasing the quantity of gold in the 

 alloy continues to depress the freezing point of the sodium, 

 until the alloy contains more than 20 per cent, of gold when 

 the minimum freezing temperature 81 9' C. (eutect temperature) 

 is reached. The case of gold dissolving in sodium may be 

 taken as a very general one, for a large number of pairs of 

 metals have been examined, and with but few exceptions, such 

 as antimony dissolved in bismuth, the effect is almost always to 

 produce a lowering of the freezing point of the solvent metal. 

 By the solvent metal we generally mean the metal which is 

 present in the largest quantity. 



A second point in which metallic alloys resemble ordinary 

 solutions is in the fact that the depression of the freezing point 

 is inversely proportional to the molecular weight of the dis- 

 solved substance. Thus, if we dissolve 342 grams (molecular 

 weight in grams) of cane sugar in 10 litres of water, and determine 

 the freezing point of the solution, it is found to be depressed a 

 definite number of degrees below that of pure water. But the 

 .same depression of the freezing point is produced by the 

 solution of 126 grams of crystalli.sed oxalic acid, or only 32 

 grams of formic acid, in 10 litres of water.'-' Alloys again 

 appear to obey the same law ; thus it is found that if we dis- 

 solve 197 grams of gold, or 112 grams of cadmium, or 39 gr.ims 

 of potassium, respectively, in a constant weight of sodium, the 

 freezing point of the sodium will be lowered by almost the same 

 number of degrees in each case. Now the numbers 197, 112 

 and 39 are the atomic weights of the metals, and it can be shown 

 that these numbers are also probably the molecular weights of 

 these elements. Hence we conclude that metals dissolved in 

 each other obey the same laws as ordinary solutions. 



The above facts for the behaviour of solutions of substances 

 delivered at Ihe Koyal Inslilutiun l>> Mr. Charles T. 

 used .xs a solvent by way of illusli 



A d 



Heycock, F.R..S. 

 3 AllhouRh 



3 Although water is used .xs a solvent by way of illustration 

 ca.ses, it should he stated that it Ls by no tneans a suitable liuuid 

 experiments, owing to the changes tt brings about in the substi 

 solved. In making such cvperiments it is Tar preferable to use b 

 acetic acid as a solvent. 



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