EkSIive-AttraSIjons of the Ra-ths. ^iiu 



humid way and in pot-afh, to exercife upon each other an eleftive attraftion. whick 

 exceeds that which unites either of them to the aliialine folvent. 



Experiment 3. The aftion of lime on filex in the humid way, is demonftrated by th« 

 precipitation which lime-water effefts iij the folution of filex in pot-aOi. The precipitate 

 is a true combination of filex and lime as M. Gadolin has announced from having icttx, 

 the experiment performed by me three years ago in my courfe * at the Polytechnic 

 School. 



An earlier ohfervation had before pointed out the truth to us, namely, that glafTes, 

 into the eompofiiiou of which too great a quantity of lime had been admitted, and 

 which are in confequence foluble in acids, do not afford in thefe folutions either a 

 fpeedy, or a ready feparation of the filex from the lime; but, on the cotjtrajry form 

 cryftalline depofitions, which mufl be treated again in order to have the complete 

 analyfis. 



I was defirous of afcertaining whether the fame phenomenon would take place with 

 bar)'tes. I poured barytic water into a folution of filex in pot-afli; the mixture foon 

 became turbid. The precipitate dried on the filtre was digefted in acetous acid, which 

 diffolved o. 3. — It is to be obferved, that the precipitate afforded by lime-water poured 

 into the folution of filex in pot-a(h when treated in the fame manner with acetous acid, 

 loll no more than o. 1. of its weight. 



Experiment 4. The aftion of ftroutian upon filex was tried in the fame manner, apdt 

 a decompofition alfo took place. But of 1 10 parts of this precipit«c dried on the fand 

 bdth, the muriatic acid rediffolved 45 in a digefling heat. 



Experiment 6. The aqueous folwtion of flrontian was mixed with that of barytei ; no 

 figns of new combination were obferved. 



Experiment 7. I have long fince fliewn that the carbonate of barytes like that of lime 

 is foluble in excefs of its own acid ; and the fame property, has been proved to exift in the 

 carbonate of ftrontian. This, therefore, afforded anew means of putting the affinities of 

 the earths into aftion. The mixtures varied with this intention afforded no phenomenon, 

 which indicated an attraSion of fufficient power, either to feparate them from the 

 carbonic acid, or to unite them in the flate of carbonate. 



Experirnent 8. Thefe refults which even by their variety, appear to charafterize mor* 

 particularly that unequal power of union which we call eleftive attraftion, or affinity, 

 induced me to make experiments on the folutions of earthi in more powerful acids. They 

 afforded me unequivocal proofs not only that there exifts among the earths a tendency to 

 unite in the humid way ; but alfo that with regard to fome of thefe earths, the union is 

 fuch asto be capable. of refifting an addition of the acid by excefs. 



* Annates de Chimie xxt!. 109 and xxvii. 3so> 



Vol, III. — December 1799. 3I Thefe 



