December 21, 1900.] 



SCIENCE. 



955 



per cubic foot per hour). The life of the 

 mantles is probably not much below 1,000 

 hours. The candle-power drops quite rap- 

 idly at first and more gradually afterwards, 

 going as low as to one-half the initial can- 

 dle-power before the mantle breaks. 



It is hard to tell how much the perfec- 

 tion of detail in burner construction, a 

 proper selection of chimney, and artistic 

 features of design have contributed to pro- 

 cure the very large commercial use of the 

 lamps. Without proper burners the mantle 

 would be of small value. The details of the 

 common burner, the peculiarities of which 

 make it different from the ordinary Bunsen 

 burner in adjustment of gas and air ; the 

 gauge distributing device to spread the 

 flame over the whole mantle and so fill the 

 mantle are too well known to merit detailed 

 description. 



The mantle first made in America, in 

 1888, gave only 35-40 candle-power initial, 

 under 10/10 pressure, using 3 to 3.2 feet of 

 gas on 3-inch mantles, and under ordinary 

 conditions not over 8 candle-power per 

 cubic foot of gas used. 



The new mantle, known as Balm Hill or, 

 popularly, ' Yusea ' mantle, has a much 

 more open mesh than the ' J ' mantle, and 

 is made on lace-making machinery. It is 

 thus supposed to be much stronger than 

 the older mantle, and gives about 100 

 initial candle-power at the mantle when 

 the gas and air are properly adjusted 

 in the burner. Your committee has been 

 unable to gather data of life or decline in 

 candle-power in time to include them in 

 this report. 



Certain defects in the mantle light should 

 not be entirely passed over. The mantle 

 is exceedingly fragile and cannot be made 

 to stand where it is subject to continued 

 vibration ; the quality of the light is such 

 as to require the adjectives cold, ghastly, 

 harsh, in describing it ; and often a green- 

 ish tinge in the light is evident. The 



candle-power drops badly early in the life 

 of a mantle, and is especially subject to this 

 trouble where there is much dust in the air; 

 the oxides seem to volatilize slowly from 

 the mantles, as evidenced by the shrinking 

 in size of strands of mantle and the white 

 deposit on chimney, for platinum melts 

 easily in the part of the flame where the 

 mantles hang. 



If the mantle breaks, a hole being thus 

 produced in it, the hot flame strikes out 

 through this, often breaking the chimney, 

 and as a secondary result destroying the 

 mantle itself. 



On the other hand, the advantages in the 

 use of the mantle for lighting are shown 

 not only by statements already made, but 

 also by the fact that artificial lighting has 

 been profoundly affected by the commer- 

 cially-successful mantle. We have systems 

 of lighting using mantles now in which the 

 source of the heating flame is gas, gasoline, 

 kerosene. There are systems using Wels- 

 bach mantles in which pressure of large 

 amount, and others in which low pressure 

 is used. There are two great companies, 

 the Welsbach Commercial Company and the 

 Welsbach Street Lighting Company, that do 

 an enormous business and deal only with 

 the use of the Welsbach mantle in lamps 

 using ordinary illuminating gas. 



The patents held in this country by the 

 Welsbach Light Company are very broad 

 and fundamental, and have to do with all 

 sorts of details of the system as well. The 

 numbers of the patents of most importance 

 are given below.* Over fifty in all were 



* 359,524, March 15, 1887. Carl Auer von Welsbach. 



377.698, Feb. 7, 1888. " " " " 



377.699, " 7, " - " " " " 



377.700, " 7, " " " " " 



377.701, " 7, " " " " " 

 390,057, Sept. 25, " Harold J. Bell. 

 396,347, Jan. 15,1889. Carl Auer von Welsbach. 

 399,174, March 5, " " " " 



403.803, May 21, " " " " " 



403.804, " 21, " " " " " 



