PLATE XX. 
lié, ib 
1. The calcium spectrum as obtained from lime ignited in the flame 
of a simple Mecke burner for two hours. 
2. The calcium spectrum as obtained from lime ignited in the flame 
of the smallest size of the Mecke blast-burner. Exposure, two 
hours, 
3. The same, with chloroform in the gas, showing the chloride 
spectrum. Exposure, two hours. 
4, The spectrum of copper oxide in the Mecke blast-flame. The 
sodium line only is distinctly seen. A green band from A 5605 
to 5560 is all but invisible. Exposure, two hours. 
5. The same, with chloroform in the gas, showing the beautiful 
banded chloride spectrum. Exposure, two hours. 
By comparing Nos. 4 and 5, it will be readily understood why traces 
of copper in the fuel show a blue flame when salt is thrown on to a 
fire of glowing coals. 
Fic. 2. 
Oxyhydrogen flame spectra of the alkali metals, as rendered by 
their carbonates. 
No. 
1. Lirntum. The red, orange, and blue lines are all photographed. 
Sodium appears as an impurity. 
. The same, with half the quantity of substance. 
. Soprum, with the red lithium line as an impurity. 
. The same, with double the quantity of substance. 
. Potassium, containing traces of lithium and sodium, as shown by 
the presence of the red and yellow lines. The potassium 
spectrum ranges from the pair of lines in the red, wave-lengths 
7699:3 and 7665°6, to the pair 4047-4 and 4044:3 in the 
violet. The continuous spectrum and lines in the green are 
well shown. The band in the red fades away on the side of 
least refrangibility. 
6. The same, with half the quantity of substance. 
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