RELATIONS OF SALTS OF ZINC AND ALUMINA TO SODA AND POTASSA. 355 
5 c. e. of solution of ZnO.SO, contain 0.1285 gram. ZnO. 
24 E i NaO * ` 0.0983 gram. NaO. 
By deducting from 7.6 c.c. the amount 2.3 c. c. required for precipitation, we have 
the amount required for resolution. 
5.8 c. c. of solution of NaO contain 0.2286 gram. NaO. 
Now 0.0983 gram. NaO will neutralize 0.1268 gram. SO,; for 
91 : 40 — 0.0983 : 0.1268. 
But the sulphuric acid in 5 c. c. of sulphate of zinc is 0,1269 gram. ; for 
80.5 : 40: 5 X 0.05108 — 0.2554 : 0.1269, 
There is, therefore, required to precipitate oxide of zinc precisely one atom of soda 
to one atom of sulphate of zinc. 
Theory requires of the sulphuric acid to be neutralized . — . . = 49.67 per cent. 
Experiment gives for the equivalent of sulphuric acid to the soda employed 49.61 " 
"[he reaction is 
ZnO . SO, + NaO = ZnO + NaO. SO,. 
- In order to re-dissolve the oxide of zinc 0.2286 gram. of NaO is required, a quan- 
tity 2.3 times as great as was required to precipitate it. To ascertain the influence of 
the quantity of water on the reaction, experiments were made with soda solution, 
of which 1 c. c. contained 0.1889 gram. of soda. 
10 c. c. of the sulphate of zinc solution required, to precipitate and re-dissolve, 2.9 c. c. 
loda solution. This is equal to 2.78 equivalents, of which one being employed to 
precipitate, there remain for resolution 1.78 equivalents. It is obvious, therefore, that 
the solution of the oxide of zinc is influenced by the quantity of water present. The 
larger the proportion of water — within the limits of these experiments — the less 
perfect was the solution of the precipitated oxide. 
Experiments with Potassa. 
Bee of sulphate of zinc solution required to complete precipitation, as the result 
' many coincident determinations, 5.1 c. c. of the potassa solution. 
B c.c. of solution of ZnO.SO, contain 0.1285 gram. ZnO 
and 0.1269 “ SO, 
5.1 e - KO contain 0.1173 * KO. 
Now 0.1269 gram. of sulphuric acid requires for neutralization 0.1491 gram. of 
