93 

 Double Salts in Solution. 



By p. N. Ea a>s. 



lu a paper presented to this Academy four years ayo, the author 

 called attention to numerous apparent exceptions to the rule that an 

 electrolyte is less soluble in a solution of another electrolyte Ayith an 

 ion in common with the first than in Ayater alone. The eyidence presented 

 at that time was that many saturated solutions fail to giye precipitates 

 on addition of second electrolytes havins' ions in common Avith those 

 already in the solutions. 



Since that time some of the cases then noted hav(> been further 

 inyestigated. and it has been proyed, as then suspected, that in these 

 cases the electrolyte is more instead of less solnide in a solution of 

 a second electrolyte Avith a common ion tlian in Ayater alone. 



The substances chosen were lead chloride and nitrate, and barium 

 chloride and nitrate. The method of inyestigation Avas the determi- 

 nation of the soluliility at zero centigrade of one compound in solutions 

 of the other of yarying concentrations up to satiiration, one hundred 

 €ubic centimeters of the solution being used in each case for analysis. 



Lead chloride Ayas estimated ))y determining chlorine in the solution 

 A-olumetrically, beginning Ayith pure Avater and ending AAitli a saturated 

 solution of lead nitrate, after saturating AA'ith lead chloride. It was 

 found that the solubility of the chloride increased AA'ith the concen- 

 tration of the nitrate, the curA'o being a straight line AAithin the limits 

 of experimental error. The solubility of lead chloride in Avater Avas 

 found to be 0.542<; grams in one hundied cul>ic centimeters of the solu- 

 tion: in saturated lead nitrate solution. 1.8'.^ grams. 



The solubility of lead nitrate in solutions of lead chloride Ayas not 

 determined, on account of the yery limited solubility of the latter. 



Barium chloride was estimated by determining chlorine in the solu- 

 tion. It Avas found in this case also that the solubility of the chloride 

 increased Avith the concentration of the nitrate, the curye again lieing 

 a straight line. The solubility of barium chloride in Ayater AA-as found 

 to be 33.89 grams in one hundred cubic centimeters of the solution: 

 in saturated barium nitrate solution, 37.42 grams. 



