272 Scientific Proceedings, Royal Dublin Society. 
The spectrum of molybdenum presents a great number of 
well-defined lines which are very evenly spaced, and extend 
throughout the plate; furthermore, the metal is a good conductor 
of electricity, does not oxidize readily when sparked in air, and 
can be obtained in a state of purity, so that it would be an excel- 
lent substance to employ as electrodes for calibrating a spectroscope 
or for the accurate determination of absorption-bands. 
Spectra 1 and 2 give the lines of the metal with the gold lines 
long and short respectively. No. 8 gives the lines of a strong 
solution long and the metal short; and no lines are given by the 
metal which are not also given by the solution, so that the sample 
of molybdenum employed was quite pure. Spectra 5, 6, 7, 8 give 
the lines developed with solutions containing 1 per cent., 0°1 per 
cent., 001 per cent., and 0°001 per cent. of molybdenum; and 
there are quite a number of persistent lines. 
(JUANTITATIVE SPECTRUM OF AMMONIUM MOLYBDATE. 
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