290 Hare’s Blowpipe. 
Experiments on Magnesia. 
Silliman, page 110. ‘‘ The same circumstances that reu- 
dered the operating upon lime difficult, existed in a still 
greater degree with respect to magnesia ; its lightness and 
pulverulent form rendered it impossible to confine it for a 
moment upon the charcoal; and as it has very little cohesion 
itcould not be shaped by the knife as the lime had been. 
After being calcined at full ignition in a covered platinum 
crucible, it was kneaded with water, till it became of the 
consistency of dough. It was then shaped into a rude cone 
as acute as might be, but still very blunt. The cone was 
three fourths of an inch long, and was supported upon a 
coiled wire. The magnesia thus prepared was exposed to 
the compound flame ; the escape of the water caused the 
vertex of the cone to fly off repeatedly in flakes, and the top 
of the frustrum that thus remained gave nearly as powerful 
a reflection of light as the lime had done. From the bulk 
oe 
of the piece (it being now one fourth of an inch in diameter at 
= 
don magazine, for a memoir which he knew to be published 
in both.* 55 ' A 
_*I mentioned above that I had lately fused a piece of oyster en agaall 
_ Ttwas exposed to the ithin an envelope of platina foil which - F 
soon reduced to a fluid globule. The application of the heat beingsusper™ 
