[ 2 °6 ] 
200 ounces of water, from a pump in Marlbo- 
rough-ftreet, were mixed with 38 ounces of lime 
water. The earth precipitated thereby weighed 38 
grains. The clear liquor, expofed to the air, and 
evaporated in a filver pan till it was reduced to 6 or 
7 ounces, depofited no more than 2 or 3 grains of 
unneutralized earth. 
A like quantity of the fame pump water, evaporated 
by itfelf without the addition of lime water, depo- 
fited about 19 grains of unneutralized earth. 
200 ounces of water, from a pump in Hanover- 
fquare, being mixed with 67 ounces of lime water, 
the precipitate weighed 93 grains. The clear liquor, 
treated in the fame way as the former, depofited 
about 2 grains of earth. 200 ounces of the fame wa- 
ter, evaporated by itfelf, depofited 28 grains of 
earth. 
The fame quantity of water from a pump in 
St. Martin’s church-yard, being mixed with 82 ounces 
of lime water, the precipitate weighed 108 grains. 
The clear liquor depofited fcarce any unneutralized 
earth on evaporation. 
The fame quantity of water, evaporated by itfelf, 
yielded 45 grains of unneutralized earth. 
The way, by which I found the quantity of un- 
neutralized -earth depofited on evaporation, was, after 
having decanted the clear liquor, and wafhed the 
refiduum with rain water, to pour a little fpirit of 
fait into the filver pan, which difl'olves all the calca- 
reous earth, but does not corrode the filver. Then, 
having feparated the folution from the infoluble mat- 
ter, the earth was precipitated by fixed alcali. 
In this way of finding the quantity of unneutralized 
earth, care muft be taken to add very little more 
* acid 
