
nn nn nnn nnn nn nn eee Nemec ee 
WITH SOLUBLE LEAD SALTS. 361 
POSTSCRIPT. 
Since this paper went to press, I have ascertained that the town water of 
St Andrews, which is one of those which gives the reaction referred to with lead 
salts, yields by evaporation, after having been boiled and filtered, 54,, of its 
weight of carbonate of lime. . Other waters may of course contain more. I also 
observe, that Fresenius found, that when distilled water was boiled a long time 
(probably, from the context, several hours) with freshly precipated carbonate of 
lime, so as to form a saturated hot solution, and this solution was then kept for 
four weeks at common temperatures, in contact with undissolved carbonate of 
lime, under frequent agitation, it yielded by evaporation ;,4,, of its weight of 
carbonate of lime.—Lvzebig’s Annalen, July 1846. In so far as regards spring 
waters, it is unnecessary to say, that Nature does not take such pains to charge 
them with lime. The method suggested above seems a more simple one, and may 
often be as effectual, possibly even more so; when the still more simple means 
of free carbonic acid are not brought into play. From the experiments of FRE- 
SENIUS, it appears, that carbonate of lead is much less soluble in water than car- 
bonate of lime, viz., in 50,551 parts, which is quite conformable to the results 
above stated. 
VOL. XVI. PART ILI. 4 Y 
