Frost Soiling Gas-light

It may surprise persons who have úrea no attcntion to such subjects, to narn that tlie illurainating power of ordinary ga depet.da, in a veiy marked ratio, upon tbo temperatura of the air in which it is burnei!. Thus, it hns been found, taking the amount of light einitted at 65 of Fahrenheit un a standard of oue bundned parta, that at 32 or the freesing-point, tbo percentags of light is -75 ; aud that at i" above aero it ia only .33, or one-third of what it ia at 65. On the otber hand, increased heat is not ooompaniod by a corresponding amouut of light, sincc ihe temperature of boíl ing water causes ao increase of only four per cent, ovor tho standard ; and tliat of 520",' or uf boilingparailine, only 18 per cent. The losa of illnininating power pon the appliuation of cold is supposed to dopend directly upon tho condensation of the hydrocarbon vspors ; ginco ata temperature of 4 a solid maas was fouud ongoaled upon tho uides of the tube, contaiuinff, araoüsr other substances,