430 ESSAYS and OBSERVATIONS 



with fait of tartar, I added eight grains 

 of this fait to twelve ounces of thefe two 

 waters; and the white powder which 

 was precipitated, when dried, weighed 

 juft one grain and a half. 



Having filtered the lime-waters of No. 

 2. and ^. into the fame bottle, before I 

 fufpedled that any thing of the lime re- 

 tnained in them, it became impoffible to 

 know, which of them afforded mofl of the 

 calcarious powder precipitated by the al- 

 caline fait ; or whether it did not proceed 

 wholly from No. 3. ; in which cafe, fix* 

 teen ounces of it muft have contained 17 

 gr. of the earthy part of the lime, and 

 No. 2. only 12 gr. 



Since No. 2. and 3. were not quite 

 free of the lime, although they had flood 

 expofed to the open air 19 days, and had 

 loft above | by evaporation ; it follows, 

 that the fureft way of knowing the quan- 

 tity of calcarious earth, contained in lime- 

 water, is to evaporate it, as Dr Langrifh 

 did^: And, if it be objecfted to this, that 

 all water affords fome earth, when evapo- 

 rated, 



* Pbj'fical experioients on brutes, p. u. 



