418 Scientific Intelligence. 
be gently ignited upon a platinum crucible with a large excess of fluorid 
i the residue introduced into the flame by the platinum 
wire. In this manner, it is found that nearly all silicates contain potash. 
The presence of salts of lithium and sodium do not sensibly affect the re- 
action; thus it is sufficient to hold the ashes of a cigar in the flame be- 
fore the slit, in order to detect immediately the yellow line of sodium and 
the two red lines of potassium and lithium 
Strontium.—The spectra of the alkaline earths are much less simple 
than those of the alkalies: that of strontium is specially characterized 
by the absence of green lines. Eight lines are very remarkable in this 
Th 
and sodium are not disturbed by the presence of strontium. The lithium 
the four spectra hitherto described by the presence of a highly erie 4 
> * . $ ¢ line, 
teristic. Aad 
Kirchhoff and Bunsen find that +55%;5 of a milligramme of chlorid 
of calcium may be easily and certainly recognized by the spectral analy- 
sis. The volatile compounds of calcium exhibit the reaction with the 
greatest distinctness : sulphate and carbonate of lime give the spectrum, — 
as soon as the salt begins to become basic. 
The compounds of calcium with fixed acids are indifferent in 
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without boiling, and at the instant that the last portions are evaporated, 
° 
