Colored Flames.

Scientific American 28, 22.3.1856

Hydrogen gas burns with a blue flame; strontium with a red flame; copper oxyd with a green flame, and many substances with a yellow flame, such as the common gas used in our streets. The cause of this must be owing to the forms of the particles or atoms under-going combustion. They must be of such forms as to reflect their peculiar colors, like a prism.

When boracic acid is present in minerals it is well known that they burn with a beautiful green flame; and Prof. Forbes, of Edinburgh, has recently discovered that chlorine produces the same result. A jet of chlorine directed upon the flame of a spirit lamp or coal gas, produces a jet of green flame. When burning alcohol is injected into a globe tilled with chlorine gas the alcohol burns at the mouth of it with a flickering green flame. When hydrochloric acid is dropped cautiously on the flame of burning alcohol a greenish tinge is observable.

Hitherto a green colored flame has been considered by minerologists and chemists as affording positive evidence of the presence of boron; but since it has been discovered that chlorine produces the same effect this test is valueless, especially when, as it often happens, chlorine and boron occur together.