358 SOME OF THE RELATIONS OF SALTS OF ZINC AND ALUMINA 
NH,Cl. Experiment gave 0.9580 gram. NH,Cl, a ratio of 5:6. These relations 
may be expressed by the formula 
5 (AL O,. 2 NaO) + 12 NH,CI = 5 (ALO, .2 NH) + 10 NaCl + 2 NH,CL 
The occurrence of the surplus NH,Cl suggested the following experiment. With 
a given alum solution in soda as above, three solutions of sal-ammoniac were taken, of 
relative strengths as 1: 2: 3. 
10 c. c. of the soda solution of alumina required of No. 1 for complete precipitation 0.3 c. c. 
113 DI DI Di Di Di No. p [14 [11 1.0 Di 
« ` « « « * — No.8 ` « 25 « 
If we multiply the number of cubic centimetres of the strongest by three, and that 
of the medium by two, we have 0.9: 2: 2.5, showing that the more concentrated is 
much more efficient proportionally than is due to the excess of chloride of ammonium 
it contains. In other words, that in proportion as the quantity of water is increased, 
so is the efficiency of the reagents enfeebled. 
Experiments with Potassa. 
se ` Chloride of Ammo- 
ven EE A nia eld to 
10 e. c. 3.2 c. c. 1.8 € c. 106 4.3 c. €. 
Di Di 113 D? [11 
é € Di Di [14 
Average, 10 c.c. 9.2 c. c. 7.9 e. c. 1.5 c.c. 4.9 c.c. 
10 c.c. of the alum solution contain 0.9710 gram. alum. 
« e e & 0.00386 “  SO,, combined with alumina. 
3.2 c. c. of the potassa solution contain 0.07360 * KO. : 
7,3 € “ D Di 0.16790 “ KO. 
53 ka - will neutralize 0.06263 * SO}. 
ES * ad “ = 0.1429 * SOjz. 
0.09386 gram. SO, — 25.30 per cent; 3 atoms — 25.30 per cent. 
0.00260 - %.. e 16.88 s 2- Ree 1686 x 
0.1400 = . SAO e 4j *  — 095 e 
According to these results, two atoms are required to precipitate, and a little more 
than two and a half to re-dissolve. Expressing these relations in formule, we 
have, 
: A1,0,.3 0, + 2 KO = Al,O,.SO, + 2 [KO . S0,]. 
2 [A1,0,.S0;] + 5 KO = 2 ALO,.3 KO + 2 [KO. SOL 
The precipitate is the same as that which, according to Berzelius, is thrown down 
