Miscellanies. 395 



article on cupellation, where the writer proposes to separate silver or 

 gold from lead by oxidizing the alloy in the external flame of the blow- 

 pipe on a slip of mica. This process is undoubtedly original with him, 

 but a much better one has been practiced by me more than thirteen 

 years, when I first learned it from Prof. H. Rose of Berlin. 



Take a few grains of bone ash, make it into a paste with a little 

 sqliva, spread it about one line thick on a piece of charcoal, and make 

 a shallow impression in it, to receive the globule of metal. Expose it 

 to the heat of the blowpipe, so as to burn it white and hard, and then 

 melt the globule of the alloy on it, and keep it in a constant red heat, 

 till the lead is all oxidized. 



The advantages of the bone ash over the mica are manifold. 1. It 

 is easier to be obtained, and every where the operator can prepare a 

 little if he should not be supplied with it. 2. The metal will remain 

 in the concavity of the bone ash paste, and not be liable to run down 

 and be lost, as on the mica. 3. It is never necessary to change the 

 material ; the bone ash absorbs the litharge which collects on the mica, 

 and impedes the process, so that the remaining metallic globule has to 

 be transferred to a fresh slip of mica. 4. The color of the paste, after 

 the operation is finished, gives an indication as to the nature of some 

 impurities of the metal ; lead alone makes it appear yellow ; a small 

 proportion of copper changes this yellow color to greenish. Respect- 

 fully, your obedient servant, Geohge Engelmann, M. D. 



St. Louis, Jan. 22, 1842, 



12. Suggested observations relating to the total solar eclipse of July, 

 1842, visible in Europe. — The sun is supposed to belong to the class of 

 nebulous stars. The nebula that surrounds him is however, at ordinary 

 times, very incompletely visible, being hidden by the efililgence which 

 his reflected beams pour upon the eye from the atmosphere, and from 

 the whole assemblage of terrestrial objects in the field of vision. It is 

 only when this eff"ulgence is withdrawn, and evening is far advanced, or 

 the morning yet distant or scarcely beginning to glimmer, that this 

 nebula may be observed in its remoter parts, lifting itself above the 

 twilight, and forming the celestial phenomenon known commonly as 

 the " Zodiacal Light.'''' At such times, however, the central body and 

 the brighter regions of the nebula are concealed beneath the horizon. 



Our only opportunity, therefore, for a complete observation of the 

 zodiacal light, in its brightness near the sun, in the gradations of bright- 

 ness as it recedes from that orb, and in the relative visual extensions 

 estimated along the zodiac and across it, would seem to be on those rare 

 occasions when one may stand, during a total solar eclipse, quite within 

 the path of total obscuration. I suppose, however, that no such occa- 



