65 
solutions. It is considered that had facilities been given for the 
removal of the free carbonic acid formed in these experiments, the 
reaction would have been considerably accelerated as the hydrolysis 
of the calcium carbonate would have been increased. 
SOLUBILITY IN HYDROCHLORIC ACID. 
Yery few authorities give any information regarding the effect 
of hydrochloric acid upon alunite. 
Rammelsberg*, however, referring to true alunite, says : “Is 
dissolved with difficulty by hydrochloric acid.” Janesf, on the con- 
trary, says: “Alunite is insoluble in hydrochloric acid.” 
As long ago as 1914 Mr. A. J. Robertson proved in the Geo- 
logical Survey Laboratory that the natroalunite from the Maritana 
Lease at Kalgoorlie was quite appreciably attacked by warm hydro- 
chloric acid, and that in fact, it was attacked approximately with 
the same rapidity as crystalline haematite. The results obtained by 
him on Sample “B,” quoted previously, containing 36.52 per cent, 
of SO. with 4.90 per cent, of Na.O and 2.46 per cent, of Iv.O, are 
as follows: — 
ulphur trioxide 
passed into 
Solution. 
Method of Solution. 
Time. 
Nature of insoluble 
Residue. 
min. 
1 • 35 
Warmed with 5 e HCl 
10-15 
White. 
3-52 
Warmed with 10b HOI 
10 
White. 
6-52 
Warmed with 10e HCl 
20 
White. 
20-38 
Boiled with 10e HCl 
30 
White. 
36-52 
Warmed with 5% KOH 
30 
Brown coloured resi- 
due and silica. 
Later experiments carried out on Kanowna alunite samples, 
containing 37.32 per cent, of sulphur trioxide gave the following 
figures : — 
Sulphur tri oxide 
passed into Solu- 
tion. 
Temperature. 1 
Time, 
Strength 
HCl. 
0/ 
/O 
1 
min. 
0-33 
70-75° C. 
10 
5e 
0-11 
75° C. 
10 
10e 
0-49 
75° C. 
20 
10e 
4-56 
100 ° c. 
30 
10e 
* Pammelsberg, 0. F. — II andbuch dor Minora lchemie, 1875, p. 274. 
t Janes, F. W. — The Alunite Deposits of Australia and their utilisation, 1917, p. 9. 
