338 Chemical Examination of Microlite. 
in their construction, to increase their elasticity, we would add, that 
all springs, which have been subjected to this process, have, for a 
certain length of time, a decided disposition to accelerate progress- 
ively ; and it would therefore appear, that some particular change 
invariably goes on in the spring after the operation of exposure to 
the fire, the nature‘of which we are at present very imperfectly ac- 
quainted with; but, from the few experiments we have made, we 
are convinced that glass is in every respect capable of being intro- 
duced into:the manufacture of chronometers. 
Art. XVI.— Chemical Examination of Microlite; by CHaries 
Uruam Sueparp, M.D. Professor of Chemistry in the Medical 
- College of the State of South Carolina. 
For my description of this mineral,* I could command only a few 
minute crystals, the largest of which weighed but four tenths of a 
Brain Had these not been possessed af considerable regularity of 
and “at the same time afforded very uniform results in the de- 
termination of their hardness and specific gravity, I should not have 
ventured on referring them to a new mineralogical species. ‘The 
recent examination however of three crystals of the same substance 
from Chesterfield, each weighing about five grains, completely estab- 
lishes the description already given, and enables me to throw some 
light on the chemical constitution of the species. 
A. A very thin fragment of one of these crystals was heated be- 
fore the blowpipe ; it turned lemon-yellow at the apex, but without 
having suffered fusion. ‘The same piece dissolved freely in borax 
with much effervescence, and formed a colorless, transparent glass. 
B. 24:5 centigrammes of the mineral, in the state of an impalpa- 
ble powder, were heated to whiteness in a platinum crucible. It 
lost 0°5 centigramme ; i. e. 2-04 p-c. 
C. Another portion in powder was treated with sulphuric acid 
in a glass tube, and heat applied. No ett pene corrosion of the 
ae was observed. 
. A few centigrammes were digested, first in dilute hydrochlorie 
acid and difterwatds i in dilute aqua-regia during several hours. The 
I was not Sonn! attacked. : 
ene vol xxvii. p. 361, and my  cantaiiis 
elo 
_ ena vol. ii. p. 45. 
