Hilary Bauerman

“ In Germany, and also in America, Wolf’s lamp, burning benzoline or petroleum spirit upon an asbestos wick, is very popular as giving a much better light than oil. Special care is, however, required in filling, so that no free liquid may be left in the holder; the spirit must be entirely absorbed by a filling of sponge, and any superfluous quantity poured off. ”

“ If the lamp is allowed to remain too long in such a fiery atmosphere, it becomes dangerous, because the gauze, becoming heated to redness, may fire the external gas. For detecting the presence of fire-damp in amounts less than 21/2%, special lamps with non-luminous flames are adopted. In Pieler’s lamp, which is of the ordinary Da form, alcohol is burned on a silk wick, and a screen is provided so that the flame can be hidden. When exposed in air containing 1/4% a cap of 11/8 in. is formed, which increases to 2 in. with 1/2%, and with 11/4% the lamp is filled with a deep blue glow. ”

“ The air for supplying the flame, entering at the bottom of the gauze and passing down the inner side of the glass, protects the latter to some extent from becoming overheated, but a large amount of light is lost by absorption in the glass, so that there is no great advantage over the ordinary Davy lamp to compensate for the extra weight and cost, especially as the safety property of the lamp depends upon the glass cylinder, which may be readily broken when subjected to the ordinary accidents of working. ”