~~ neti - 
Notice of Topaz and Phenakite. 331 
It is scratched by beryl. Sp. gr.=2.80...2.97—varying in dif- 
ferent specimens, chiefly on account of slight intermixtures of 
grains of quartz, or albite. _ 
Before the blowpipe, in very thin fragments, it phosphoresces, 
turns white, and fuses with difficulty into a milk white, semi- 
blebby globule. With borax, it forms a transparent glass; and with 
the microcosmic salt, fuses into an opaque, white globule. Thir- 
ty-three centigrammes, in the condition of an impalpable powder, 
after heating for fifteen minutes in a platina crucible, lost 0.75 
centigramme. It was then mingled with three times its weight 
of anhydrous carbonate of soda, and ignited for one hour. ‘The 
mixture shrunk into a somewhat firm, white, porous mass. It 
was crushed in a mortar and treated with hydrochloric acid. A 
perfect solution was thereby obtained, with the exception of cer- 
tain flocculi of silica. The silica was separated and ignited: it 
weighed 18 centigrammes, or 55.81 p.c. The solution from 
which the silica had been separated, was precipitated with ammo- 
nia. ‘This clear supernatant fluid was tested for lime and mag- 
nesia without detecting either of those earths. The precipitate, 
while moist, was largely treated with a solution of carbonate of 
ammonia, by which it was almost wholly taken up after a period 
18 hours,—frequent agitation having been employed to favor the 
‘solution. The undissolved residuum, which was trifling in quan- 
tity, compared with the portion taken up, was dissolved in hydro- 
ehloric acid, and to it were added sulphuric acid and potassa. No 
crystals of alum were formed; from whence it was concluded 
that the undissolved matter was chiefly glucina. Had not other 
engagements intervened, it would have been easy to have com- 
pleted the analysis on the portion of mineral first pulverized ; but 
sufficient information has perhaps been gained, to afford a proba- 
ble corroboration of the opinion originally made up from its natu- 
ral properties. 
I suspect the existence of Phenakite also at Paris, in Maine, 
where I obtained many years ago, small, white, hexagonal prisms 
in granite, associated with tourmaline; and which I then sup- 
- posed to be beryl. I regret that my collection in this city does 
not furnish me with the means of putting this conjecture to the 
test. 
New Haven, May 29, 1838. 
