224 Scientific Proceedings, Royal Dublin Society. 
Sizicon. (Plate XIV.) 
The last four spectra on this plate show the effects of diluting 
a solution of silicate of sodium. The lne \ 3303 is a sodium 
one; and the subsequent lines are due to silicon. The lines of 
silicon do not develop in acid solutions, and quite large quantities 
may be present in acid solutions of other elements without giving 
any indication of their presence when sparked; so that for the 
detection of silicon, it is absolutely essential to spark an alkaline 
solution. The group a little beyond gold line No. 25 is very 
characteristic, and easily recognized. 
QUANTITATIVE SPECTRUM OF SILICATE OF Sopa. 
Intensity Intensity 
Wave-length. and Wave-length. and 
Persistency. Persistency. 
4131-0 Ap | 
4128-2 Ap PES yO ca 
ap ee EL! 2528°6 8h 
3905-8 5 2524-2 Gp 
ae 2519-3 8 
2881-7 10 2516°2 10W 
Ae og noni ee 2514+4 7 
2631-4 8 2507-0 8 
