the potash and soda being determined in the filtered extract. The 
results obtained were : — 
(a) Half-gram of mineral, roasted, moistened with 50 cc. 
cold water and let stand overnight ; the solution was decanted 
off, then 50 cc. of hot water added, warmed for one hour on water 
bath, filtered and washed with hot water. 
(b) Half-gram of mineral, roasted, taken up with 50 cc. hot 
water, allowed to stand on water bath for one hour with frequent 
stirring, decanted and retreated for a further hour with 50 cc. 
water, filtered and washed with boiling water. 
(c) Half-gram of mineral, roasted, taken up with 100 cc. hot 
water and allowed to stand on water bath for 5 hours with occasion- 
al stirring,, then decanted and treated for a further 5 hours in a 
similar manner, then filtered and washed. 
(d) Ha If -gram of mineral, roasted, taken up with 50 cc. of 
water, allowed to stand for one hour on a. water bath with fre- 
quent stirring, then filtered and washed with boiling water. The 
residue was then transferred to the beaker and retreated for a 
further hour under similar conditions, again filtered and washed 
and then again retreated. 
(a.) 
(b) 
(o.) 
(d.) First extract 
Second extract 
Third extract 
Potash, 
Soda. 
0/ 
• n 
0/ 
/ n 
4-98 
2-92 
4-96 
2-94 
5-00 
2-90 
4-66 \ 
2- 76\ 
•36/5-02 
•18/ 
traces traces 
These figures show that after calcining the mineral at 800° C. the 
potassium sulphate formed is very readily soluble in warm water. 
Another sample (D) of high grade al unite, giving an ignition 
loss of 41.44 per cent, gave the following figures: — 
NaCl + KC1 
K b O 
Na 2 0 
2 hours leach- 
ing. 
100 cc. water 
Of 
16° 18 
7-10 
2-54 
3 hours leach- 
ing. 
100 cc. water. 
O' 
,o 
16-20 
7-10 
2-55 
960° Centigrade . — To determine the effect of over roasting 
in the presence of common impurities, one hall'-gramme lot of a low 
grade alunite ore was heated to the melting* point of silver (900° 
C.) and the results showed a loss of water soluble potash due to the 
formation of an insoluble potassium compound, probably a potas- 
sium alumino-silicate, by interaction between the first formed 
