IN CONNEXION WITH THE SPECTBUM OF THE SUN. 
643 
Some so die fluoride was inserted into one of the aluminium cups, and opposite was 
placed a clean blunt aluminium point* ; the small coil and a jar were employed. 
On passing the spark, D only was seen. The break was then readjusted and the spark 
made heavier, but the result was the same. Some new and moist sodic fluoride was then 
placed in the cup, but the result still remained as before. 
Sodic Chloride was then treated in the same way, a fresh aluminium pole being 
reserved for it and placed opposite to its cup. D was present and was bright; the 
double line in the red once flashed in, but it was not again seen though the cup was 
charged and recharged with the salt repeatedly. 
Sodic Bromide treated in the same way gave D, the red line being seen but once ; 
D, however, was brighter than before. 
Sodic Iodide treated as above gave D and the red double line, which remain constantly 
visible, the double green line near D being also occasionally seen. D was intensely 
brilliant, and the salt fumed away from the pole in a dense white smoke. 
The following day a fresh attack with more powerful apparatus was made. One of 
App’s 6-inch quantity coils and a jar with about 224 square inches of coated surface 
were employed with a powerful battery of five one-pint Grove’s cells. The results, 
however, went exactly in the same way. Na I and NaBr gave all the metallic lines of 
sodium, which were very brilliant ; whilst Na Cl gave D and the double red very bright, 
and stretching all across the spectrum. Na F gave also D and the double red line ; but 
the latter only extended three quarters across the spectrum, and neither D nor the red 
line was so bright as they were in the chloride. Further observations showed that under 
certain circumstances all the lines appeared even in these latter salts ; but they were so 
dim as to be scarcely visible, and the fact of these compounds behaving in direct contra- 
vention to the observations with lead was established. 
Lithium. 
The following experiments were made with lithic iodide and chloride in coal-gas. 
Lithic Iodide gave the red line of this metal, 6705, extending all across the spectrum, 
but it was very faint. 6102, the orange line, was very brilliant and about two thirds 
across. 4603, the blue line, was very short and nebulous when seen, which was only on 
one occasion. This differs but little from the spectrum given by the metal itself, except 
that the lines are in the latter case much brighter, and that the red and orange extend 
right across the spectrum, and the blue three quarters across. 
A line at 4972 was seen also in the spectrum when the metal was used; but this has 
never been seen by Kirchiioff, Thalen, or any other observer except FIuggins, in 
lithium. 
Thalen, however, saw this line alone in caesium, of which metal it constitutes the 
entire spectrum. 
FIuggins has nevertheless included this line in his map of the lithium spectrum. But 
* Special precautions being taken to keep the poles the same distance apart in all the experiments. 
