SOME NEW MODES OF LIGHTING. 271 



New methods of eleetrie I'Kjht'tng. — As early as 1878 Archercaii. 

 Carre, and Gauduih soiight to augment the luminosity of the electric 

 arc by renderino; the arc itself as well as the positive carbon incandes- 

 cent. For this purpose they mixed with the carbon of the electrodes 

 suitable substances such as oxides of calcium or magnesium; l)ut 

 unfortunately there occurred a precipitation of the refractory oxides 

 upon the lower carbon, and a formation of scoria which resulted in a 

 prejudicial unsteadiness for illumination. After the Welsl)ach man- 

 tle attained success, new efforts were made to aj^ply this principle of 

 incandescence of the arc, and ^lonsieur Bremer exhibited at the expo- 

 sition of 11>00 a model having four special carbons, and in which the 

 light produced in the arc was reflected downward. The presence of 

 mineral matter resulted in increasing the luminous surface, modifying 

 the color of the light as desired, and in diminishing by one-half the 

 current consumption for a given illumination. 



A considerable number of concerns, notably in (Termany,.are now 

 producing flaming arc lamps more or less pattei'ned after that of 

 Bremer. The principal differences consist in the varied construc- 

 tion of the electrodes, but all are composed of mixtures of carbon 

 .and some salt of calcium, usually fluorspar. Professor Wedding, 

 having studied the influence of this substance on the consumjition 

 of energy in the lamj), has found that the most favorable conditions 

 are found with 15 per cent fluoi'spar. Electrodes of this composi- 

 tion are found to consume but O.IT) watts jier candle, as comj)ai*ed 

 with 0.5 watts for the ordinary arc. 



Doctor Arndt's researches at the Technische Hochschule in Berlin 

 have shown that the operation of the flaming arc does not involve 

 any appreciable production of objectionable gases. Furthermore, 

 the light produced is of a yellowish-red color and nnu-h less cold and 

 harsh than that of the ordinary arc. It more resembles sunlight in 

 color, and penetrates better through fog than the light of shorter 

 wave length produced by the ordinary arc. 



The Bremer arc recjuires the use of special lamps, but by employ- 

 ing trizonal carbons A. Blondel has avoided this inconvenience. 

 Minerals are contained in the two interior zones, and such arcs, con- 

 suming only 3 amperes, have been found to give nearly three, and 

 similar arcs, consuming amperes, more than four, times the effi- 

 ciency of the ordinary arc light consuming equal energy. 



In the same general category belongs the lamp with three elec- 

 trodes and two arcs, devised by L. Sigfried Andersson, of Stockholm. 

 For the purpose of increasing the area of luminous surface, and at 

 the same time producing incandescence within the arc, there is 

 introduced between the two carbons which carry the current a third 

 cylinder, formed of a more refractory substance than the two others. 

 The regulation of this lamp is very delicate, and is effected in a most 



