Professor Gordon <m iht Melting Points of Metals. 11 



in the same circumstances, an alloy of 1760 mill, gold -J- 230 milL 

 platinum can bo maintained in fusion ; and if either more gold, or a 

 very small quantity of platinum, be added, the fusion is imperfect 



2°. An alloy of gold and platinum was found having the same melt- 

 ing point as cast iron, viz., 70 gold + 30 platinum fused in the same 

 time as 100, by weight, of cast iron. 



The melting point of platinum is deduced from these experiments 



"" From 1* 25290 C.\ w.._. 05340 c 



and these experiments appeared satisfactorily to warrant the assump- 

 tion that alloi/s of silver and gold, and gold and platinum, have melting 

 points proportional to the melting points of each of these metals; an 

 assumption made by Prinsep. 



Mitscherlich's determination of 1560" C. as the melting point of 

 platinum was referred to, but as this involves all previous determina- 

 tions of the melting points of other metals being erroneous, that is, 

 much too high, Plattner was justified in assuming his own determina- 

 tion as the basis of the temperatures given in Table II. and in his 

 further researches. 

 The melting points of Lead being taken at 334° C. 



Silver, — 1023° C. 



Gold, — 1102" C. 



Platinum, — 2534° C. 

 it was easy, according to the method described, to determine the melt- 

 ing points of the most refractory substances, so long as these were 

 under that of platinum. The alloy being found having the same 

 melting point as that of the body under research, its value was 

 then 



A s + B s' 



100 



Where A and B are the weights, and s and s' the melting points of the 



metals contained in the alloys. And 100 parts by weight of alloy, and 



body under experiment, were taken respectively. 



Attention was called to the circumstance that Daniell had fixed the 



melting point of copper at 1091° C, or under that of gold. Prinsep 



found, from constant experience as an assayer, that this is not the 



case, and fixed the melting point to be the same as that of an alloy 



of 97 parts gold and 3 parts platinum. Plattner found 95 parts gold 



and 5 platinum to answer more exactly, and hence, applying the above 



formula, 



^ __ 95 X 1 102° 4- 5 X 2534" ,._^ 

 X j^ =117^ 



the molting point of copper. 



The second part of Plattner 's researches on the Determination of the 



