()() 
SOLUBILITY IN II YDWOFLUOIMO ACID. 
No reference could be found to the effect of hydrofluoric acid 
on al unite. 
Owing* to I lie close resemblance in many respects of al unite to 
kaolin, for which it may be mistaken, the effect of that reagent was 
tried to determine if this acid could be used to distinguish between 
the two minerals. 
The mineral ujeed for these experiments was the same as used 
for the solubility in caustic soda solutions, being 99 per cent. pure. 
The experiments were carried out in plat inum vessels and stirred 
from time to time. 0.5 gm. lots of the mineral were taken and the 
acid used in each case was equal to 5 cc.. 25 E hydrofluoric acid, the 
results being: — 
Strength of Acid. 
Time. 
Temperature. 
Alunite in Solu- 
tion. 
min. 
5e 
15 
90° C. 
Complete. 
10e 
30 
20° C. 
Little. 
10e 
5 
90° C. 
Complete. 
The solution of the mineral in warm hydrofluoric acid is therefore 
very rapid. The solution contains a mixture of potash alum and 
aluminium fluoride. 
SOLUBILITY IN SULPHURIC ACID. 
Only one reference was found regarding the effect of sulphuric 
acid on alunite. .Janes, in referring to the effect of acids on alu- 
nite, says: “Is soluble in strong sulphuric acid on heating.” 
The mineral on which these experiments were carried out was 
99 per cent, pure, with 2.46 per cent. Iv.O and 4.90 per cent. Na.O. 
The results obtained were as follow: — 
Strength of Acid. 
Time. 
Temperature. 
Alunite in 
Solution. 
5e 
1 hr. 
90° C. 
Trace. 
10e 
1 hr. 
90° C. 
Little. 
36b 
1 hr. 
90° C. 
Much. 
36 e* 
10 min. 
200° C. 
Complete. 
* It \vi>s found ting on cooling tlic solution anhydrous sulphates were thrown out 
of solution. 
