Holborn and Day — Melting Point of Gold. 145 



Art. X. — On the Melting Point of Gold; by Ludwig 

 Holborn and Arthur L. Day. 



[Communication from the Physikalisch-Technische Reichsanstalt, Charlottenburg, 



Germany.] 



In connection with the measurement of high temperatures 

 with the gas thermometer,* the melting points of various 

 metals lying between the temperatures 300° and 1100° were 

 determined. The two methods, employed were distinguished 

 by the names " Wire Method " and " Crucible Method." The 

 wire method consisted in inserting into the hot junction of the 

 thermo-element about l cm of the wire whose melting point was 

 to be determined, and observing the E.M.F. at the moment of 

 melting and consequent interruption of the circuit ; the cru- 

 cible method, on the other hand, involved the introduction of 

 a thermo-element properly protected by porcelain tubes into a 

 comparatively large mass of the metal. The melting point of 

 gold was determined at that time by the wire method only. 



On account of the special importance which has been attached 

 to the melting point of gold for comparing the temperature 

 scales of various observers, it seemed to us advisable to make a 

 further determination of this melting point by the crucible 

 method as well, and at the same time to investigate whether 

 the surrounding atmosphere exerts any influence on the melting 

 temperature. 



For this experiment some 450 gr. of pure gold were used, 

 the purity being vouched for by the Gold- und Silber-Schei- 

 deanstalt at Frankfort-on-Main, where it was obtained. For 

 the sake of certainty, however, a sample weighing 2 gr. was 

 also analyzed in the chemical laboratory of the Reichsan- 

 stalt, but no impurities were found. 



The gold was melted in the same oven which was described 

 in the former paper, and measured with the same thermo- 

 element which had served for the observations by the wire 

 method. 



Preliminary trials made with a smaller quantity of the 

 metal (350 gr.) in a thin porcelain crucible yielded ill-defined 

 u time curves " on account of the small latent heat of fusion, 

 and also a difference between the melting and solidifying tem- 

 peratures amounting to as much as 4°. -Afterward, using 450 

 grams of gold and placing the light crucible in a larger one 

 lined with asbestos, the distribution of heat was more even and 

 excellent results were obtained. Crucibles of mixed graphite 

 and clay with walls 5 mm in thickness also yielded satisfactory 

 results, in fact we afterwards restricted ourselves to these 



* Ludwig Holborn and Arthur L. Day, this Journal [4], vol. x, p. Ill, 1900. 



A.M. Jour. Sci.— Fourth Series, Yol. XI, No. 62.— February, 1901. 

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