360 RELATIONS OF SALTS OF ZINC AND ALUMINA TO SODA AND POTASSA. 
The foregoing results may be presented in the following formule. 
Sulphate of Zinc and Soda. 
Y ZnO.S0, + NaO = ZnO + NaO. SO; 
Sulphate of Zinc and Potassa. 
2. 4 [ZnO . S0;] + 3 KO = 4 ZnO : SO; + 3 [KO . 80]. 
- Sulphate of Alumina and Soda to Precipitation and Resolution. 
3. 2 [Al, O,. 380,] + 5 NaO = 2 Al, O; . SO, + 5 [Na0 . SO;]. 
4. 2 A1,0,.S0, + 5 NaO = 2[A1,0,. 2 NaO] + NaO. SO. 
Re-precipitated with Sulphuric Acid. 
5. Al, O;.2 NaO + SO, = Al, 0,. NaO + NaO.SO,. 
Re-precipitated with Chloride of. Ammonium. 
6. 5 [A1,0,.2 NaO] + 12 NH,Cl = 5 [ALO,.2 NH;] + 10 NaCl + 2 NH,Cl, 
or, probably, 
A1,0,. 2 NaO + 2 NH,CI = AL0,.2 NH, + 2 NaCl. 
Sulphate of Alumina and Potassa to Precipitation and Resolution. 
T- Al, O, DH 8 SO, — 2 KO = Al, O, -SO, a 2 [KO e SO;]- 
8. 2 [A1,0,. 80,] + 5 KO = 2 A1,0,.3 KO + 2 [KO. SOL 
Re-precipitated with Sulphuric Acid. 
9. 2 A1,0,.3 KO + 380, = 2 Al, O; + 3 [KO. SOL 
Re-precipitated with Chloride of Ammonium. 
10. 2 A1,0,.3KO + 6 NH,Cl = 2 [A50,. 3 NH,] + 6 K Cl. 
It is probable that in some of these reactions the salts, represented in the formule 
as in solution, are in part more or less firmly combined with the precipitates. It is un- 
questionable that water enters into the constitution of many of the precipitates. The 
formule give only the relations of the quantities to the facts of precipitation, reso- 
lution, and re-precipitation. They illustrate, also, incidentally, the influence of water 
on the efficiency of a reagent. 
