Intelligence and Miscellaneous Articles. 319 



heated by means o£ a Schloesing pipe, we Mere able to fix and mea- 

 sure temperatures near 1200°. This furnace (constructed, like the 

 first, by M. Wiesuegg) gives even with facility temperatures much 

 higher than 1200°, but of which it has not yet been possible 1o 

 effect the direct measurement. In the experiments at 800 and 

 1000 degrees the temperatures, measured with the manometer of 

 the air tliermometer, were obtained by bringing the gas to the same 

 volume (making allowance for the variations of volume of the por- 

 celain balloon) at the commencement and at the end of the experi- 

 ment and noting the variation of pressure. In the present experi- 

 ments we operated both by variation of pressure and by variation 

 of volume; so that the temperature was measured each time in 

 two different ways. Thus were found: — 



0-0388 at 116°8, j ^^l te™pemture being given | ^/ ^^^ ^^°. 

 ' \ by the two measurements J 



0-0388 ., 1168, „ „ „ 1169 „ 1166 



0-0389 „ 1194, „ „ „ 1195 „ 1192 



Therefore the mean specific heat between zero and 1177° is 

 0-0388. 



All these measurements are faithfully summed up in the following 

 formula, ^vhich may therefore be regarded as giving the mean spe- 

 cific heat of platinum between zero and t degrees up to 1200°: — 



q=0-0317 + 0-000006^, 



From this are deduced :- 



C,^°o=0-0323 

 Co=^°°= 0-0329 

 C,'°''=:0-0335 

 C/°°=0-0341 

 O/°°=0-0347 

 r''°o=0-0353 



C/°° =0-0359 

 C/°° =0-0365 

 C„^°° =0-0371 

 C/°°= 0-0377 

 C,^i°° = 0-0383 

 r^^°«=0-0389 



We have thus the necessary data for the exact measurement, by 

 a simple calometric experiment, of any temperature between zero 

 and 1200° ; we have also, by the same, the means of quickly deter- 

 mining any other specific heat — that of carbon for instance, which 

 I have already attacked. 



The true specific heat of platinum at t degrees, — , is, within 



the same limits, 



7,= 0'0317 + 0'000012i, 

 which gives 



y,,,=0-0329, y,,,=0-0377, y,,,,=0'0437, y,,,,=0-0461 



II. I he quantity of heat was measured which is given up by 1 

 gramme of solid platinum from the fusing-point to zero. For this 

 purpose a certain quantity of platinum was melted ; into the fused 



