498 .a ; report — 1882. 



eight minutes. The fused metal had a brilliant granular fracture. It could not 

 be cut properly in the shaping machine, shearing off under tlie tool. One pound 

 of grain nickel fused in carbon dust for twenty-five minutes yielded a dark grey 

 carburised metal, which worked well under the tool. On another occasion an 

 equal quantity of nickel, similarly treated, gave a 'blowy' metal, which could not 

 be worked. Some carburised nickel, made as described above, was fused in a clay 

 crucible for twelve minutes, and allowed to cool gradually in the furnace ; the 

 fracture became whiter, and the grain closer. 



Copper. — Three-quarters of a poimd of copper were fused for about half an 

 hour in carbon-dust. On examining the result, it was found that all but about 

 |-oz. had been vaporised. Those who were present during the experiments 

 suffered no ill effects from the atmosphere charged with copper, which they must 

 have breathed. 



Platinum. — Eight pounds of platinum were rendered perfectly liquid in about 

 a quarter of an hour. 



Tungsten. — Half a pound of tungsten in powder was subjected to the action 

 of the arc in a clay crucible. Dense fumes were evolved, a cavity about 1^-in, 

 across the top being formed. The furnace was allowed to cool down slowly. 

 When the crucible was removed, it was found to ha'Ne been very much attacked 

 below the point to which the arc extended. The inference is that the crucible had 

 been attacked by the metal at the temperature of the experiment. The metal was 

 fused only to an inappreciable depth beneath the cavity formed by the arc. The 

 imfused metal underneath was covered with very beautiful iridescent crystals of 

 tungsten, which under the microscope appeared to be well-formed prisms. They 

 have not yet been measured. The crystals had evidently been formed by tlie slow 

 cooling of the vapour distilled down from the surface. 



A very large numlier of experiments was made with tungsten, the residts of 

 which showed that it could not be fused, except in very small quantities at a time. 

 It was possible to build up a small ingot by fusing a little of the tungsten, and 

 then adding little by little gradually. Even then the pieces obtained were for 

 the most part spongy and \insatisfactory. The best results arrived at were when 

 tungsten which had already been fused was employed in the building-up process. 

 When once the metal had been fused, it did not fume much in melting, doubtless 

 owing to the greatly reduced surface exposed. 



Tmigsten fused in the electric furnace is, when untarnished, pure white, and 

 brittle, the grain being very close. Tungsten hitherto has only been obtained as 

 a grey powder, by reducing the oxide with carbon or hydrogen, or in minute 

 globules in the ordinary small electric arc. Tungsten has its fusing point lowered 

 by the addition to it of carbon. Under these conditions a solid piece of moderate 

 size can, without much difficulty, be obtained. From 1,000 grains of powder fused 

 in carbon-dust 650 grains were recovered, the remainder having been volatilised, 

 and from 450 grains of the fused metal 410 grains were obtained on re-fusion. 

 One piece of tungsten which had been treated under the conditions most likely to 

 cause it to be highly carburised was analysed. It contained 1-8 per cent, of carbon. 

 The metal was very white, close in grain, and brittle. 



From the foregoing experiments it is clear that the amount of any given 

 metal which can be successfully fused in the electric furnace, and the time required 

 in effecting the fusion, are dependent on (a) the relation between the volatilising 

 point and the fusing point, i.e. the extent to which the volatilising point is higher 

 than the fusing point ; (6) the conductivity of the metal for heat. 



It thus happens that platinum can be more readily melted than steel, and 

 in greater quantity for a given expenditure of energy. This inference is 

 believed by Professor Huntington to be justified by the observations and experi- 

 ments so far made. 



It still remains to examine chemically the specimens referred to in this 

 paper. 



I 



