Inquiry Into tht Laws of Affinitj, ^©3 



OKigen at an ordinary temperature; but at a higher temperature the difference of dilation 

 fufficiently deftroys the rcfulting affinity of the pot-a(h to caufe the iron to combine with 

 the oxigen. 



In the oxigenated muriatic acid, the oxigen which has undergone but little faturatlon, 

 and which confequcntly is feebly retained by the muriatic acid, pafles eafily into other 

 combinations ; but though it is found in a much greater proportion in the oxigenated 

 muriate of pot-alh, it is carried off with much more difficulty by oxigenable fubftances. 



The phofphate of lime is not decompofed by charcoal, even at a great degree of heat J 

 but if it be in the ftate of acidulous phofphate, the portion of acid, which may be confi- 

 flered as in excefs at the ftate of faturation, is capable of being decompofed by charcoal, 

 becaufe it is not prevented by a fufficiently large mafs of bafe ; and it is this part alone 

 which affords phofphorus, when, in order to obtain this fubftance, we ufe phofphate of. 

 lime reduced to an acidulous phofphate by the fulphurlc acid. 



9. The contrary takes place when, inftead of a faturaiing fubftance, which ferves as »• 

 fupport to the refulting affinity, one is added that tends to form a combination in which- . 

 one of the conftituent parts muft enter. For example, when fulphuric acid is added to a 

 mixture of water and iron, this acid favours the decompofirion of the water, becaufe it 

 tends to combine with the metal, and with a proportion of oxigen ; a tendency concurring, 

 with that of the metal againft the affinity which forms the combination of oxigen withi 

 hidrogen. 



10. From the preceding remarks it may be concluded, that the properties of the rc*- 

 fulting affinity of compound fubftances may be reduced, i. to the advantages of liquidity,, 

 and under this point of view it is neceffary to apply to it the theory of folvents (Art. IX.) ;; 

 2. to the difpofition ft) folidity, which produces contrary effedls, which muft be explained 

 t)y the force of cohefion (Art. V.) ; 3. laftly to the concentration of elaftic fubftances ; this 

 eircumftance demands particular confideration, but it may be found combined with one 

 of the two preceding. 



The obfervations prefented in No. 7 and No. 8 prove, that in thofc compounds in which 

 elaftic fubftances are concentrated, there are eftabliflied by a change of conftitution, affini- 

 ties which may be confidered as new ; an additional force has accrued, to which we may 

 apply the inverfe of what has been ftated relative to the effe(£ts oLelafticity (Art. VI.) 



The diftindive character of the complex- affinities, of which 1 have treated (Art. XII.) 

 compared with thofe which refult from the compofition of the fubftances of which I now 

 fpeak, is, that in the firft but very little change obtains in the conftitution of the compo- 

 nent parts; fo that when the force of cohefion or elafticity does not intervene, we may 

 conGder them in the fame manner as they have been confidered in Article XII, N0..1., 

 whereas a new force is eftablilhed in compounds in which elaftic fubftances are condenfedj. 

 a power which may be confidered analogous to that of the cohefion which obtains onithe 

 mixture of different fubftances that determine the combinations that are formed,, or which, 

 •cquire to be overcome by the forces oppofed to it.- 



8. !!!• Caloric,, 



