French National Tnfuiutei l8^ 



names of the feven old planets. C. Champeaux, ingenieur 

 dcs mines, Is the tirft who difcovered Uranite in France. The 

 details of this difcovery have been communicated to us by 

 C. Lelievre. 



Chemifts have given the name of affinity to that power by 

 which different fubftances tend to unite with each other, and 

 which properly forms the objeft of all their refearches ; for 

 chemiftry will never be complete until we obtain a table of 

 tlie degrees of affinity of each fubftance for all the reft under 

 given circumftances. What renders it difficult to form fuclx 

 a table is, that thefe affinities do not prcferve the fame order 

 in all circumftances. It has been long known, for example, 

 that this order varies according to the degrees of heat ; but 

 feveral other caufes, to which chemifts have not hitherto 

 paid fufficient attention, concur alfo to render it uncertain. 

 C. Berthollet has been employed on this part of chemiftry, 

 and has prefented on that fubjeft a work of great labour, a 

 portion of which he communicated to the Inftitute of Egypt, 

 and which proves, that in going to fearch for new fafts in a 

 diftant country, he has been the occafion of making new 

 progrcfs in the theory which ought to unite them. 



Among the caufes which change the order of affinities is, 

 the refpeilive quantities of each of the fubftances brought 

 into contact. One fubftance, which would exercife no aftioa 

 if it entered the mixture in a quantity equal to the others, 

 ftxercifes a very perceptible aftion when its quimtity is con- 

 fiderably augmented : it fcems, then, that the diffi;rent parts 

 of each fubftance unite their efforts to overcome the refift- 

 ance oppofed to them. 



Another of thefe caufes is, the greater or lefs cohefion of 

 one of the fubftances or mixtures. It augments the refiftance 

 to the change which, the affinities ought to produce. 



A third caufe is elafticity, which leffens the tendency to 

 combination. Thus any fubftance, oxygen for example, afts 

 with a far greater force when concentrated in a liquid com- 

 bination than wheu it is under the claftic form. The adlion 

 of heat feenis to enter into this third caufe. It may be pof- 

 fiblc that it dvics not alter the affinity of the different fub- 

 ftances but by producing changes in their refpe6tive elafti- 

 Vol. VJ. Bb cities: 



