Inquiry Into the Lawt of Affinity. .^5 



both its affinity and Its quantity. In proportion as the latter was reduced, the precipitate 

 was again diflblvcd'; notwithftanding which, there were fome remains of ammonia after a 

 long evaporation, and it was only by means of the aftion of the air that jt was entirelf 

 dilTipated. The feparation of the lime would doubtlefs become much more fenfiblc, if 

 ammoniacal gas were received in a flightly diluted folution of the muriate of lime. 



When ammonia produces a precipitate with the falts that have alumine for their bafe, k 

 is becaufe this earth is lefs foluble than lime, even when it is combined with the portion of 

 acid which it retains when precipitated. 



ARTICLE Xir. 

 On Complex Affinities. 



I. I (tiall proceed to examine, under the more general name of complex aJUnity, what 

 has been confidered as due to the concurrence of four affinities, and which has been com- 

 monly known by the name of double affinity. 



To give an idea of the adlion of four affinities, Bergman examined the effe£t which takes 

 place on mixing the folution of the fulphate of pot-affi with that of the muriate of lime. 

 It is, fays he, the fame as if the proportions of fulphuric and muriatic acid, of lime and 

 pot-afl], which entered into the compofition of thefe falts, were put in the quantity of 

 water employed ; the two bafes aft by their affinities upon the two acids : but though the 

 affinity of the pot-afli for the fulphuric acid be ftronger than what it has for the muriatic 

 acid, yet the affinity of the latter for the pot-a(h, added to the affinity of the fuU 

 phuric acid for the lime, gives an aggregate of forces greater than the affinity of the 

 fulphuric acid for the pot-afli, and that of the muriatic acid for lime : thus an exchange 

 of bafes is determined ; fo that inftead of fulphate of pot-alh and muriate of ilme, we 

 have fulphate of lime and muriate of pot-afh. This explanation is always founded on 

 the fuppofition that the affinities are conftant powers, independently of the quantities and 

 fiate of faturatlon. 



1. When two bafes a£l together upon an acid, the latter Is divided, or rather divides it* 

 aftion in proportion to their mafles ; and if inftead of one we have two acids, and no 

 feparation is efFeiSted either by precipitation or cryftallifation, both the acids will a£t 

 equally upon the two bafes in the proportion of their mafles. If each of thefe acids were origi- 

 nally combined with a bafe, the amount of the mutual forces of the acids and alkalis, after 

 mixing the folutionsof the falts, will be the fame as before. No muriate of pot-afli nor fulphate 

 of lime are formed ; but there will be a combination of pot-afli, lime, fulphuric acid, and 

 muriatic acid, which will give the fame degree of faturatlon as before the mixture. Hence 

 it is, that on mixing two falts, which, by exchange, ought to produce combinations that 

 would have very difl^erent proportions of principles, there Is not, as has been juftly re- 

 marked by Guyton, cither the acidity or the alkalinity which would neceflarily appear 

 if fuch a change were really to take place. 



Vol, v.— May 1861. ' K 3. The 



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