The Ayr* lamp has an arrangement by which the air passes through a valve ; the valve closes whenever the atmosphere becomes light or filled with foul gas, and thus extinguishes the lamp.
The !Luc-oder lamp, much used in the Belgian coalmines, is larger than the English lamps. A glass vessel surrounds the flame. The air can only reach the flame over the top of the glees, which is covered with wire-gauze. Over the glass, and as a continuation of it, is a wire-gauss cylinder, having a braes top full of minute holes. A small metal chimney pierces the horizontal disc of gauze which covers the to give an outlet for the flame and the products of combustion. The air must plus downwards through this lamp before it can reach the wick. The iluesaler lamp gives • good light, and is very safe against explosive mixtures; but it is heavier than the English lamps, and its unprotected glass vessel is liable to fracture; moreover, if held a little sloping (which is very likely to occur In use), the flame goes oat.
The Lemielle lamp, also used in Belgium, is a sort of Davy lamp, with a glass cylinder fitting tightly inside it, and extending about half the height. The wiregauze is spread out at the bottom into a trebly thick flat rim ; and the arrangement Is such that the air to feed the flame must peal down through the treble gauze rim into a space between the top of the oil-vessel and the wick, and then up again to the wick in the narrow glans cylinder.
The Whitehead lamp consists of an iron cylinder, with on one side a bull's-eye eurrounded by reflecting surfaces. The air to support com bustion paired through a number of small orifices round the ell recep tack, and thence through wire-gauze. The air admitted is purposely
mud! In quantity. Wire-gauze Is also introduced at the top of the chimney, so as to complete the isolation of the flame.
There are many ether form, of mfety-lamp which have engaged the attention of practical men,—such as Elide., a Belgian lamp intended to give more light than is usually obtained; Fyfe'a, something like Clanny's, but having double gauze at the top instead of single ; Watson s, which low apparatus fax locking up the lamp in such a way that the miner cannot open it until it needs to be trimmed ; Bender non'a, with a double glass cylinder, having water between to cool the outer Doty's, a Belgian lamp with gauze and glees; 3fartyn Roberti's, having a contrivance for extinguishing the flame if the lamp should be broken ; Olover'a, having two concentric glames, and en arrangement for making a current of cool air circulate between them. Borne hays been made with the wire-gauze electm-silvercd, in order to reelect more light ; seeing that it ham been found by Mr. Goldsworthy Ournr7, that when dull iron wire la used, three-fourths of the light I lost.
Amid much diversity of opinion concerning the relative merits of various kind. of mfety-lamp, there is a pretty general agreement that the gauss cylinder should be aocompanied by one of glean, to moire the action of krone currants of air ; and that the glass without the geese is not sufficiently protected against fracture.
LAM l'IC ACID. Another name for iltddiydic acid. (ALDLIITDICI Acts).