94 Hartiny-—An Investigation of the Connexion ¢:tween 
the hottest part, that is to say very near to the point of the inner cone of the 
flame, which proceeds from the nozzle delivering the oxygen, otherwise the 
peculiar and distinguishing character of the spectrum may escape being photo- 
graphed ; for instance, the continuous rays and subordinate series of lines in the 
potassium spectrum may fail to appear, or the blue line of lithium, and one in the 
ultra-violet, may be wanting. 
The treatment of soluble salts is described in the following notes, this being 
somewhat different from the treatment of solid substances, insoluble compounds, 
or elements. 
Liruium. 
An alcoholic solution of pure fused lithium nitrate was prepared, containing 
0:0069 gr. of metallic lithium in 1:0 ¢.c. of alcohol. The requisite quantity of 
solution was delivered, from a graduated pipette reading to 715 of a cubic 
centimetre, on to an ashiess filter-paper 10 cms. in diameter; ten of such papers 
when burnt showed feebly only the sodium spectrum, with no trace of the lines 
of lithium. The paper was dried in an air-bath, and the dried filter was cut into 
strips about 3 cms, broad ; these strips, being very tightly rolled up spirally, were 
burnt slowly, with the highest temperature obtainable in the oxyhydrogen flame. 
The flame measured 12°5cms. x 1:8 cms. when illuminated by the substance. 
Edwards’ Isochromatic plates were used, which were developed with ‘imogen 
sulphite,” 
Peet Description of the Spectrum photographed. 
uantity o 
Tithium. 
The following lines were observed, measured and identified. 
0-0131 er. The wave-leneths varied but slightly from those more accurately 
0-0110 gr. measured by Ramage; his figures are given.* ddA 4603-07, 
00096 er. 4132:98, and 3282-82 their intensities varied with the quantity 
of substance. 
0-0089 er. AX 4132°93 and 3232°82. These lines became weak. 
09-0082 gr. | Bere: But 
0-0041 gr. | The line \ 4603-07 alone was visible. 
0:0020 er. No line visible, except the red \ 6708. 
The results show that when the most persistent line \ 4603:07 is photographed, 
there cannot be less than 4 mlgrs. of lithium in the flame during the period of 
exposure ; similarly, when three lines are photographed, there cannot be less than 
* Proc, Roy. Soc. 71, 164-71. 
