238 J. L. Smith on determining the Alkalies in Minerals. 
num crucible capable of holding three times the bulk of mixed 
powder. The platinum crucible should then be placed in one of 
earthern ware, with a little magnesia on the bottom. (I always 
prefer the crucible made in F'rance, called Beaufay’s crueible to 
enclose platinum crucibles, when heated in a furnace, as their 
form and cleanliness make them superior to the Hessian crucible 
for this purpose.) The crucible may then be covered and intro- 
duced in any form of furnace where a bright red heat can be 
procured, 
17. Ihave been using a common open portable furnace, heap- 
ing charcoal over the top of the crucible; and so easily does 
the effect take place, that in no instance has there been a 
failure of complete decomposition with as simple a-means of 
heating as the above, and 1 have ascertained that an alcoholic 
lamp, with a large circular wick, such as Jackson’s lamp, urged 
with a bellows, will answer for making a complete decomposition 
of Zircon in twenty-five minutes. This circumstance is not sta- 
ted to recommend the use of a lamp for every mineral decompo- 
sition, when a simple portable furnace and charcoal are so acces 
sible, and their effects so much more to be depended upon thana 
lamp. rom 30. minutes to one hour’s exposure to the heat 1s 
recommended. 
$ 
on, were Zircon, Kyanite, Beryl, Topaz, Spodumene, Marge 
rite, Margaurodite, and Feldspars of different descriptions. All 
were readily decomposed by the method just described, and with- 
out any particular care in levigating them; one gramme of the 
tained—which was 64:8 per cent. wath little iron. This © 
cludes the first point to be considered in this article, namely, ne 
means necessary to render the silicates soluble ; the next poilt a 
the separation of the alkalies. ae 
ed IL. Separation of the other ingredients from the Alkalies. a 
is laid = 
its side in a capsule of platinum or lain, the latter ca2 
2 fed porcelain tne 4 
used with perfect Safety to the accuracy of the result. A eee 
tity of dilute hydro-chloric acid is poured into the Epes 
part of acid to two of water; the whole is heated over 4 “ 
