INCANDESCENT MANTLES. 



By ViviA>' B. Lewes, F. I. C, F. C. S. 



There is nothing more wearying- to the practical man than to listen 

 to the preachings of the scientist who imagines that the thoughts born 

 within the four walls of his study are superior to the hard-earned 

 experience of years of labor, and nothing is further from my intention 

 than to impose this sufl'ering upon you. There are, however, sides to 

 many questions which can })e made clear; details, the explanation of 

 which can help, and innovations, the description of which will interest 

 those employed in actual every-day work, and it is in this way that 

 lectures can be made most valuable, while the more practical working 

 experiences find their most fitting record in the discussion which every 

 lecturer hopes to excite. 



It was long before the incandescent mantle came to the help of the 

 gas engineer in his fight against the threatened encroachments of the 

 electric light that the name of Auer von Welsbach became known to 

 the scientific world as one of the most promising students in the 

 domain of the rare earths that the world-famous la])oratories of Hei- 

 delberg and Vienna had produced. 



Boiling a solution of some of these rare oxides, and using a ragged 

 sheet of asbestus card to shield the beaker containing the solution of 

 the salts from the fierce flame of the Bunsen Inirner, he noticed that a 

 small quantity of liquid, having boiled over and having evaporated on 

 the projecting fibers at the edge of the card, endowed them with the 

 power of becoming brilliantl}^ incandescent under the exciting jicjit of 

 the nonluminous flame. Seizing the clew thus obtained, Welsbach set 

 himself to solve the problem of how to utilize the manifestly high 

 light emissivity of these bodies as a practical aid to artificial illumina- 

 tion, and the result of that quest has been to place the gas industry 

 well beyond the reach of electrical competition for many years to 

 come, and to insure fame and more substantial reward to the keen 



> Paper read before the Institution of Gas Engineers, on May 3, by Vivian B. 



Lewes, Professor of Chemistry, Royal Naval College, Greenwich, England. Printed 



in Progressive Age. Reprinted in Scientific Anieri(;an Supplement, Nos. 1230, 1231, 



July 29, August 5, 1899. 



o87 



