and the Results of its Alteration. 263 
For the above analysis the ratio is, nearly :— 
a tn 5 men pon . eres 
No. 2 : 
This corresponds to the nin os Al,Si,O,, the percentage 
composition of which, given above, agrees well with the 
ana 
The composition obtained for B was:— 
B. Insoluble portion. 
Calculated to 100. Calculated from formula. 
No. 2. No. 2. 
SiO, 46°06 68°18 68°62 
Al,O3 13°56 20°07 19°56 
Na.O 7:94 11°75 11°82 
67°56 100°00 100-00 
The ratio calculated from the preceding analysis is :— 
as : Al,Os : ers 
No. 2 1-07 10 
This ratio is very 2 that of Wis viz: 1:1, so that 
the formula for the insoluble portion is Na,Al, 
n analysis was also made of sample No. ‘ bas, ‘the separa- 
tion was a little less complete than of No. 2; the first diges- 
tion in acid left behind a very little of the soluble mineral, as 
shown by the presence of lithia in B, and then in the subse- 
quent treatment of the insoluble part ‘Gin which also KOH was 
employed) there seemed to have been a slight decomposition of 
the albite. The results, although for the reason given hardly 
worth putting on record, were satisfactory in this, that they 
confirmed those of No. 
The point thus far established may be stated as follows: 
A chemical examination proves that the substance, called 
Herkewier J 8 spodumene, is vas a dis 5g dece'any 9 only 
av 
ery uniform mixture of t inerals ; of thes ean 
by us sts Herat he iges pik gelatiplzation: in hdposhitakts 
acid, and has oe ag ‘3 2i,0,; the mere not 
seen to be that ® given above. That the mixture is truly 
insoluble residue B a tgs left after the digestion in sodium 
carbonate, was in one case examined under the microscope, a 
found to be crystalline, and to have the peculiar semi- aon 
ah belonging to the pseudomorphous albite, as described 
elow. 
he microscopic examination of thin sections of # spodu- 
mene confirms the results reached from the chemical side as to 
