108 Proceedings of Learned Societies. 
due to both the metals; but if the metals made use of are approxima 
— pares the spectrum is hardly to be distinguished from that of the 
e metal. In the case when alloys are used as electrodes, it is not al- 
the more volatile metal which impresses its spectrum most strongly, 
thongh an alloy of three parts of gold and one of on gave a spectrum 
in which the lines due to silver predomina 
The author then proceeds to describe a number of experiments upon 
the anima of sparks between aleetroiles of different metals in a — 
uthor esti od that many of these gases, such as protoxyd 
eer greiat ae a and sulphurous acid, presented a considerable ob- 
to the passage of the sparks from the induction-coil, 
higher refrangibility, which were quite intercepted by glass, but that 
quartz transmitted these rays freely, Aonontings he was led to procure 
prisms and a lens of quartz, which, when applied to the examination ¢ 
ieee aic are, or of the dischar. rge of a Leyden jar, by fora 
ubstance, re 
as the visible spectrum. This long spectrum, as formed 
iehags arc with copper electrodes, was exhibited at a lecture given 3 
Royal Institution i in 1853; but, the Athan, for reasons he alien 
rays ae to! saaiapelialy ox: dated As the bright aluminum lines 
2 ‘high refrangi Sabet do not appear to have been by photography, § 
