§ 13 Mr. Philip Harry’s Sensitive Flame
Mr. Philip Barry has discovered a new and very effective form of sensitive flame, which he thus describes in a letter to myself: “It is the most sensitive of all the flames that I am acquainted with, though from its smaller size it is not so striking as your vowel-flame. It possesses the advantage that the ordinary pressure in the gas-mains is quite sufficient to produce it. The method of producing it consists in igniting the gas (ordinary coal-gas) not at the burner but some inches above it, by interposing between the burner and the flame a piece of wire-gauze.”
I give a sketch of the arrangement adopted in Fig. 138. The space between the burner and gauze was 2 inches. The gauze was about 7 inches square, resting on the ring of a retort-stand. It had 32 meshes to the lineal inch. The burner was Sugg’s steatite pinhole burner, the same as used for the vowel-flame.
The flame is a slender cone about four inches high, the upper portion giving a bright-yellow light, the base being a non-luminous blue flame. At the least noise this flame roars, sinking down to the surface of the gauze, becoming at the same time invisible. It is very active in its responses, and, being rather a noisy flame, its sympathy is apparent to the ear as well as the eye.
“To the vowel-sounds it does not appear to answer so discriminately as the vowel-flame. It is extremely sensitive to A, very slightly to E, more so to I, entirely non-sensitive to O, but slightly sensitive to U.
“It dances in the most perfect manner to a small musical snuff-box, and is highly sensitive to most of the sonorous vibrations which affect the vowel-flames.”