1821.] Causes of Calorific Capacity, Latent Ileal, fa. 203 



v „ nnr T _ T m-T' N '- = H±li, by substituting for N 

 ceding cor. t = — ^ + N t — 3 ' J ° 



the numeratom of the water, and N, the numeratom of the mer- 

 cury ; their values 2 and 1. g : 1008 . 3 + 10 68 , 5 



Hence in the experiment I have quoted t = s 



= 1028-4, which by Table III. corresponds with 59-6° of Fah- 

 renheit ; that is, -4° below the experiment. 



Dr Henry also tells us, that if the same temperatures be used, , 

 but reversed with respect to the bodies ; that is, if the water be 

 nut at 100°, and the mercury at 40°, the temperature of the mix- 

 ture will be nearly 80°. With these data, and the preceding 

 tables, we find T = 1068-5 and T, = 1008-3, and, therefore, r 



_ 2 x 1Q68-5 + io° 8 ' 3 _ 1048-3, which brings out the Fahren- 



— 3 



heit temperature 79-5°, or -5° below the experiment. 



The same author tells us, that if two volumes of mercury be 

 mixed with one of water at the same temperatures, 100 and 40 , 

 it matters not whichever of these has the higher temperature; 

 the temperature of the mixture will be 70°. Now in this case, 

 as the mercury is double in volume to what the water is, there 

 will be twice the number of particles of mercury in this experi- 

 ment to what there was in the last; and, therefore, for N, we 



2T + 2T, 



must put twice N„ and the formula becomes t = 4 — 



x (T + T x ) . which is a symmetrical function of T and T, of the 

 simplest kind. It is no matter, therefore, if two given tempera- 

 tures be used, whether T or T, be put for the higher, the result 

 will be the same, which so far agrees with what Dr. Henry says. 

 Let T = (100° Fahrenheit) 1068-5, thenT, = 1008-3 and T = 

 J. x 2076-8 = 1038-4 or 69-6° of Fahrenheit; that is, -4° 

 beneath the experiment. _ ~- 



Sir H. Davy, in his Elements of Chemical Philosophy, has 

 mentioned an experiment that would require a different ratio for 

 the numeratoms from that which I have given. Dr. Murray, in 

 his Chemistry, has given results still different from those of Sir 

 H. Davy. MM. Lavoisier and Laplace, Dalton, Irvine, Wilcke, 

 Ki'rwan, and Crawford, have all given results so widely differing, 

 that the extreme specific capacities determined from these expe- 

 riments have a ratio no less than that of 5 to 2 ; so that on only 

 50° of Fahrenheit, the extreme experiments would not agree 

 within 30 ° ! ! To expect to have any general law to connect and 

 ao-ree with experiments so unaccountably discordant would be 

 absurd in the extreme. The best course which it appears 

 to me can be taken in this case, is to select the experi- 

 ments of a single author, and from one of them to determine 

 the numeratoms, and then compare the theory with the rest; 

 for it is highly probable, if he conducted all his experiments, the 



