the Laws ofJffJui/y. t 9 ' 9 



k. From thefe considerations, T fhall proceed to deduce, 

 mil, the theory of the uncryflallizable refiducs found in 

 evaporated folufionsof falts : it will Be confirmed bv the fuc- 

 eeeding obfer'vatiou;,. 



Saline fubftances exercifc upon each other an aclion which 

 increafes their fallibility, an etfecl that has been particularly 

 eilabi iflied by Vauquelin. {Amuilcs de Chime, torn, xiii.) 

 This mutual aclion varies in the different falts. ft has, how- 

 ever, been thought, that falts with an earthy bale do not in- 

 creafe the folubility of the nitrate of potafh, though thefe in 

 reality inereafe it the molt. There is in this refpeel a dif- 

 ference in the effect produced by the falts, which depends 

 on their nature; but this difference is in general very fnlalf, 

 compared with that which proceeds from the force of crystal- 

 lization. 



D. Equal parts of nitrate of potafh and fulphate of potafh 

 afforded by evaporation, fuceefiively, and in proportion to their 

 folubility, fulphate of potafh and nitrate of potafh , ( without 

 leaving any uncryftallizable liquid ; but the fame experiment 

 being made with nitrate of foda and fulphate of foda, both 

 of which have only a flight tendency to cryftallize, and are 

 nearly of equal folubility,~only a frnall quantity of fulphate 

 of foda was feparated by cryftallization ; all the reft remain- 

 ing liquid, without any cryftallization. A mixture of mu- 

 riate of foda and fulphate of alumine having been fubmitted 

 to the fame proof, it was clearly perceived that the two fa]ts 

 had become more foluble; but they were entirely feparated 

 by alternate evaporation and cooling. Sifbltanees, therefore, 

 which poflefs a confiderable force of cryitallization, though 

 rendered more foluble, feparate on account of their mfoiu- 

 bility, and leave very little or no uncrvftallizable rcikiuum. 

 But the mutual action of falts, which have only a feeble dif- 

 poiition to cryftallize, counterbalances their force ot cryftal- 

 lization, fo that there then remains much liquid which can- 

 not cryftallize ; particularly when the refiduum contains a 

 fubthmee in itfclf ururyil.iUizable ; as in experiment C, 

 where, by the proportions employed, there was found a 

 fuperabundance of nitrate of lime, which by its aclion v.- 

 the nitrate of potafh reduced a confiderable quantity of that 

 fait into an uncrvftallizable liquid. How earnest, then, 

 that the mofl learned chemifts, Lavoifler, Fourcfoy, Vau- 

 quelin, Guiton, and the Commiffiries of the Aeadcmy of 

 Sciences, among whom myfelf was one, could have been 

 led, by the experiments made upon the proof of faltpetre, 

 to believe that the nitrate of lime exerts no aclion upon the 

 Ultra te of potafh, ilor incrcafed its folubility ? {AmiaUs do 



N 4 Qhhm* 



