Proportion ef Jcid in Salts, ^c. 273 



it is feen why a certain degree of preflure is required to force mercury through a fmall aper- 

 ture, and a fmall quantity of this fluid may be retained in a cloth without pafling through. 



A few experiments were made by the author to determine the elevations and reaftions 

 when the plates were feparated by the interpofition of a wire of known thicknefs. When the 

 diftance was four thirty-third parts of a line, the elevation of the vvater was 15 lines and a 

 half. — When it was four forty-ninth parts the elevation was 33 lines and a quarter; 

 and when it was one twenty-eighth part the elevation was 74 lines. But, from fome dif- 

 ficulties which prefented themfelves, it was not practicable to meafure the adhefion farther 

 than to determine that they were much lefs than the preflure of a column of water, having 

 the furface of the plate for its bafe, and the column of liquid for its height. 



Ohjervatlons on the Proportion of real Acid in the three ancient known mineral Acids-, andon- 

 the Ingredients in various neutral Salts and other Compounds. By RjCHARD KlRWAN^ 

 Efq. LL.D. F.R.S. and M.R.l.A. ( Continued from page %\$.) 



Of the Ufe ofthefe Tables. (Without abridgement. J 



Prob. I. x\.N extratabular fpecific gravity being given, but intermediate between fome 

 of thofe in the table, to find the quantity of real acid in 100 parts of fuch acid liquor. 



I ft. Find the difference betwixt the next higher and lower tabular denfities =: D^ and 

 alfo the difference betwixt their acid contents = D'. 



2d. Find the difference betwixt the extratabular i^. gravity and the next upper or next 



lower, whichever it is neareft to, = d, and let the difference betwixt its acid contents 



(or quantity of real acid) and thofe of the next upper or lower = d, which is the quantity 



D' d 

 fought; then as D. D' ; : d. d, then</ = - — , confquently d added to the acid contents 



of the lower tabular fp. grav. or fubtraded from the upper, is the quantity fought. 



Note. In general when ^, that is, the difference between the extratabular fp. grav. and any 

 tabular fp. grav. does not exceed -rol -o it is infenfible, and the acid contents of the lower or 

 upper, whichever is nearefl:, may be afcribed to it. 



Prob. 2. The quantity of real acid'in 100 parts of an acid liquor being given but extra- 

 tabular, being intermediate between fome of the quantities in the tables, to find the fp. grav: 



o/'fuch acid liquor. 

 Find D, D' and 

 lower tabular fp. grav. or fubtraded from tlie upper, gives the fp. grav. fought. 



Find D, D' and d as in the foregoing problem ; then d — ' ,.,; then d, added to the 



;rav. fought. 



But 



