188 J. M. Ordway on Watergiass. 
More trials have been fully carried out with chlorid of sodium 
as a precipitant than with any other salt, on account of the ease 
and precision with which or may be determined. Many of 
the precipitates were simply squeezed by hand, because it was 
only after making siniiereblae orate ss that I found out the ad¢ 
vantage of resorting to mechanical aid,—No. 3, above, being in’ 
fact about the fortieth experiment. Among the following instan- 
ces, the term ‘hard pressed’ refers to the effect of a screw multi- 
plying the power 680 times, minus the loss by friction. For the 
sake of pt the numbers have in each case been made 
to correspond to 100 grms. of waterglass solution though twice 
or one-half that. quantity was sometimes actually u pete 
4-100 grms. of 25 p.c. NaSigg, with 200 grins. of 25 p.c. NaCl, 
gave a large precipitate, which was ste washed with cold water. ‘The 
ignited residue weighed o nly 3°22 orm 
5.—100 g. of 25 p. ec. NaBios, with 200 g. a 25 p.c. NaCl, yielded 47 ge 
of a squeezed precipitate wholly soluble in water and containing 34 
p-¢. of mother-liquor and 42°7 p.c. of NaSigg3, 
In the mother-liquor there were 1'7 p. ¢. of NaSiz-s¢. 
6.—100 g. of 25 p.c. c. Nadigs, with 100 g. of 25 p.c c. NaCl, gave 45°5 ge 
of a soluble product containing 31 p. c. of mother- “liquor ‘and 42°8 p. ¢ 
0 
In the mother- ee there were 2°7 p.c. of ia 
7.—100 g. of 25 p.c. NaSigs, with 50 g. of 25 p.c e. NaCl, gave 40°9 g- 
ofa — saint containing 23 p. c, of mother-liquor and 45°9 p. ¢. of 
Na 
In ‘he mother Tighor there were 4°8 p. c. of NaSij-s2 
8.—100 g. of 25 p.c. NaBig:s, with 25 g. of 25 p. ¢. NaCl, afforded 33°3 
g. of a soluble precipitate containing 23 p.c. of mother-liquot and 
42'5 pic: of NaSig.gg: 
In the ——e there were 10°7 p. c. of NaBia. 
9.—100 g. of 10 p. c. NaSig.s, with 100 g. of 10 p.c c. NaCl, gave ote 
of an opaque eee not Seragk mene in meat Jt ‘contained 5 
ing 49 p. c. of NaSig.s is 
11.—100 g. of 25 p.c. NaSias, with 100 g. of 25 p.c. NaCl, gave 31 
g. of a oe Bee curd containing 29 p. c. of mother-liquor 
and 42°5 
Ih the mather-liquot there were 6 p. c. of NaBi;. 
12\—100 g, of 25’ p. c. NaSigo;, with 50 g. of 25 = ce. NaCl, gave pe 
g. of a soluble precipitate containing 33 p. ¢. of mother-1 iquor 
38'8 p. c. of NaSio.50. 
In the ier Fad ars were 12 p.c. of NaSiz10 
13.—100 g. of 10 p. c. NaSio25, with 100 g. of 10 p. ¢. gi 2S" 
1:15: g. of a partially. soluble precipitate containing 30°8 ; 
hee 100 g. of 25 p. c. NaSi,, with 400 g, of 25 p.c. NaCl, Y neld &. 
a hard: pressed, soluble product containing 7-7 p. c. of rmother-liquo? 
- 61°2 p. c. of NaSig¢go. 
The — contained 19-8 p. c of NaSij-50. 
