1826.] Rev.Mr.EmmeMntlmMtion,^ '431' 



its fluxion will be a ; make the area equal to the S^^Mflc lieat ; 

 then the capacity for heat, i.e. fluxion of the abscissa x ordi- 

 nate, will be the fluxion of the area : hence the capacity is the 

 fluxion of the specific heat. When then the ratio of at least 

 three capacities of a body shall be experimentally found, the 

 nature of the curve will be known, since it isfi/ x. In all cases 

 the capacities of weights, proportional to the atomic weights, 

 and which may be called atomic capacities, must be registered, 

 as also the specific heats of the same ; these will represent the 

 capacities and specific heats of the atoms themselves. Thus, if 

 the specific heats of two atomic weights A, B, be S, s, the capa- 

 cities will be S and s : during combination, if no change take 

 place, the specific heat of the compound will be S +5; andthe^ 

 capacity S + 5 ; but if a change take place in the capacity, the 

 corresponding change in the specific heat cannot be known 

 untiiy 3/ X is known. If we examine a number of cases, we shall 

 find that during combustion the capacity is generally diminished. 

 Using Dalton's table of capacities of equal weights, the atomic 

 capacity (1 atom) of oxygen 38*00 + atomic capacity of hydro- 

 gen (1 atom) 21*4 = 59'4 ; the capacity of aqueous vapour = 

 13*95 ; hence the diminution of capacity, measured by the same 

 scale, is 45*45. 1 atomic capacity of charcoal 1*56 + 2 atoms, 

 capacity oxygen 76*00 == 77*56 ; that of 1 atom of carbonic acid 

 = 23*1 : hence the diminution is 54*46. The capacity is always 

 diminished when heat is evolved during combination ; but the 

 change of capacity is not in the direct ratio of the heat evolved, 

 except the capacity be proportioned to the specific heat, in which 

 case the specific heat may be represented by the logarithmic 

 curve. 



In all cases of combustion in oxygen, or of combination with 

 gaseous matter, an equal condensation of the gas does not take 

 place. By the above-mentioned formula, having given the rela- 

 tive weights of the elements of a binary compound, the specific 

 gravity of one of the substaiices, as well as that of the compound, 

 that of the other may be found ; for c being the sp. gr. of the 



compound, b = . The oxygen being b, its spe- 



m + n, a — m . c 



cific" gravity, as it exists in phosphoric acid, = 5*1 ; in black 

 oxide of manganese 3*1, red lead 3*2, iron mica 2*28, glass of 

 antimony 2*21, red copper ore 1*47, oxide of arsenic 1*4. From 

 these examples, oxygen seems to be most condensed by those 

 bodies which have the greatest attraction for it, i. e. by those 

 whose electric stete is most remote from that of oxygen, or 

 which have the least force of gravity ; and these are the bodies 

 which evolve most heat during combustion. If chlorine be the 

 supporter, the inflammables follow a different order ; another with 

 iodine 5 and another for sulphur, &c. according to their respect- 



