TO SODA AND POTASSA. 935" 
10 c. c. alum solution contain 0.3710 gram. alum. 
& “ S “ 0.09386 “  SO,, combined with alumina. 
1.4 c.c. soda solution “ 0.0602 NaO. 
e * will neutralize 0.07767 *  SOj. 
2.7 c.c. soda will contain 01101 .*. NaO. 
ES 
E * correspond with 0.1498  * SO. 
0.09386 gram. SO; = 25.30 per cent; 3 atoms = 25.30 per cent. 
007707 4 u 12098. * z "2932107 " 
0.1498 "o E 00 S ae LO TA 
According to these results, two and a half atoms are required completely to pre- 
cipitate the alumina, and a little more than an equal quantity to re-dissolve the precipi- 
tate. Expressing these relations in formule we have, omitting the sulphate of potassa 
of the alum, 
2 [AL 0,. 3 80,] + 5 NaO = 2 ALO,. SO; + 5 [NaO . SOL 
2 Al, Os. SO; + 5 NaO = 2 [A]; 0;. 2 NaO] + NaO. SO,. 
The sulphuric acid of the precipitate may be more or less withdrawn by long con- 
tinued washing, showing how feeble the affinity is, where the action of water in quan- 
tity is brought to bear on both the constituents of the precipitate. 
The constitution of the soda and alumina compound in the resolution differs from 
that of the soluble compound prepared by fusing together alumina and carbonate of 
soda, by Schaffgotsch,* which. had only one atom of soda to one of alumina. 
If these two atoms of soda to each atom of alumina require, in order to the precipi- 
tation of the alumina, two atoms of sulphuric acid, we have, 
2 of 0.1161 gram. NaO — 0.04644 gram. 
0.4644 * Nath correspond with 0.059991 “ of SO,. 
Lee of the sulphuric acid solution contained 0.03264 “ 
a quantity but little more than one half that required to neutralize the SO, The 
formula will be therefore 
Al, O;.2 NaO — SO; = Al, 0; . NaO a NaO.SO,. 
It is not to be denied that this result seems inconsistent with the solubility of the 
compound obtained by Schaffgotsch, unless it be admitted that the alumina which has 
been combined by heat with soda is modified in its properties. 
The precipitation with chloride of ammonium required a little more than a full 
equivalent. #2 of 0.1161 gram. NaO = 0.4644 gram., and require 0.8014 gram. 
* Pogg. Ann., LIII. p. 117. 
