On the Gas Blowpipe. 335 



Parnassus by the author. It was fused, but with great difficulty, 

 exhibiting after fusion a white milky enamel with points of intu- 

 mescence that were transparent." 



Experiments on Magnesia. 



Silliman, page 110. " The same circumstances that rendered 

 the operating on lime difficult, existed in a still greater degree 

 with respect to magnesia; its lightness and pulverulent form ren- 

 dered it impossible to confine it for a moment upon the charcoal; 

 and as it has very little cohesion, it could 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 frustum 

 that thus remained gave nearly as powerful a reflection of light 

 as the lime had done. From the bulk of the piece (it being now 

 one-fourth of an inch in diameter at the part where the flame 

 was applied) no perceptible sinking could be expected. After a 

 few seconds, the piece being examined with a magnifying glass, 

 no roughness or earthy particles could be perceived on the spot, 

 but a number of glassy smooth protuberances whose surface was 

 a perfectly white enamel. This experiment was repeated with 

 the same success. Mav not magnesia then be also added to the 

 table of fusible bodies ?" 



Notwithstanding the previous publicity of these results obtained 

 by my friend and myself, Dr. Clark, in the following note, en- 

 deavours to convey an impression ol the incompetency of my ap- 

 paratus to fuse lime and magnesia. Note 5, page 46. " Pro- 

 fessor Hare in America could not accomplish the fusion either of 

 lime or magnesia by means of his hydrostatic blowpipe. See 

 Annates de Ckitnie, \on\ey}y. page 12()." But why overlook 

 Silliman's experiments? It is moreover strange that an English 

 writer should refer his readers to the French Annales in prefe- 

 rence to a London magazine, for a memoir which he knew to be 

 published in both*. 



• I mentioned above that I had lately fused a piece of oyster shell lime. 

 It was exposed to the flame within an envelope of platina foil, which was soon 

 reduced to a fluid globule. The application of the heat beini; suspended 

 (when both substances had become cold), the earth was found adhering, on 

 the top of the metal. This enabled me to make it receive the greatest heat of 

 the flame on renewing the process. The lime then melted into a liquid, 

 whicli .subsiding round the globule of platina caused it to appear after cool- 

 ing as if set in enamel. 



Clahk. 



