Daniell on a New Ppotneter. 319 



drawn from a very clifFerent method of reasoning, which I 

 think will convince those who are at all conversant with the 

 effects of heat upon metals, and the management of a furnace. 

 Mr. Wedgwood fixes the heat of an enamelling furnace, at 

 1857°, and the fusing point of fine silver at very considerably 

 more than double, viz., 4717°. Now, any body almost knows, 

 how very soon silver melts after it has attained a bright red 

 heat, and every practical chemist has observed it to his cost, 

 when working with silver crucibles. Neither the consumption 

 of fuel, nor the increase of the air-draught, necessary to 

 produce this effect, can warrant us in supposing that the fusijig 

 point of silver is 4J times higher than a red heat, fully visible 

 in day-light. Neither on the same grounds, is it possible to 

 admit that a full red-heat being 1077°, and the welding heat of 

 iron 12,777°, that the fusing point of cast iron can be more 

 than 5000° higher. The welding of iron must surely be con- 

 sidered as incipient fusion. 



Much, however, very much remains to be done in this wide 

 field of research ; and when it is considered, what important 

 results have arisen from the accurate estimation of the degrees 

 of heat, comprehended within the scale of that invaluable instru- 

 ment, the thermometer, it is surely sufficient to inspire ardour 

 in our inquiries, into the almost boundless range of which that 

 instrument measures comparatively so small a part. Happy 

 indeed shall I be, if it shall be found that I have been fortunate 

 enough to suggest the means of advancing one step in a pur- 

 suit, which promises so much benefit to science and the arts. 



I shall now terminate this paper by the record of two facts, 

 which although not in immediate connexion with the previous 

 inquiry, have arisen collaterally from it, and I believe are new 

 and worthy of attention. The first is, that mercury amalga- 

 mates readily with platinum at about its boiling temperature. 

 The combination is very intimate, and it requires a strong red 

 heat to volatilize the mercury from it ; the platinum is then 

 left in a honey-combed or dissected state. 



The second is, that a piece of cast iron strongly heated, and 

 afterwards slowly cooled in a muffle, became covered with 



