April 2, 1915] 



SCIENCE 



487 



and more complete cure by the introduc- 

 tion of vapors of metals or metallic salts 

 or oxide in the arc itself, so as to modify at 

 wiU the color of the light, and thus he be- 

 came the inventor of the so-called ' ' flaming 

 arc." It is noteworthy that it took about 

 twenty years before electricians and il- 

 luminating engineers became so convinced 

 of the advantages of the flaming arc, that it 

 had to be "reinvented" during these late 

 years, and now it is considered the most 

 eifieient system of are-illumination. 



In relation to this invention, it is inter- 

 esting to quote the following extract of the 

 specifications from his United States Pat- 

 ent 210,380, filed November 4, 1878 : 



This rod or stick may be made of various mate- 

 rials, as, for example, of so-called "lime glass," 

 or of compounds of infusible earths and metallic 

 salts, silicates, double silicates, mixtures of the 

 silicates with other salts of metals, fluorides, 

 double fluorides, mixtures of the double fluorides, 

 fusible oxides, or combinations of the fusible 

 oxides with the silicates — the requirements, so far 

 as the material is concerned, being that it shall be 

 capable of volatilization when placed on the outer 

 side of the electrode to which it is attached, and 

 that its vapor shall be of greater conductivity than 

 the vapor or particles of carbon disengaged from 

 the carbon electrodes. The foreign material added 

 to the carbon may be incorporated into the elec- 

 trode by being mixed with the carbon of which 

 the electrode is composed, or it may be introduced 

 into a tubular carbon; but I have found it best to 

 place it in a groove formed longitudinally in the 

 side of the electrode, as shown. 



In his endeavors to make the electric in- 

 candescent lamp an economic possibility, 

 we see him introduce over and over again, 

 chemical methods and chemical considera- 

 tions. He first tried to utilize platinum 

 and iridium, and their alloys, which he 

 fused in a specially constructed electric 

 furnace, devised by him, antedating the 

 furnace described by Siemens. This is 

 probably the first electrical furnace, if you 

 will except the furnace which Hare used in 

 his laboratory in Philadelphia. 



But these platinum metals showed serious 

 defects aside from their high cost, and by 

 that time, Weston had become so familiar 

 with the properties of good carbon that like 

 other inventors, he became convinced that 

 the ultimate success lay in that direction. 



And now we see him join in that race of 

 rivalry among inventors who all engaged 

 their efforts in search of the real practical 

 incandescent lamp. Among this group of 

 men, the names of Edison here in the 

 United States and that of Swan in Eng- 

 land, have been best known. To go in the 

 details of this struggle for improvement is 

 entirely outside of the scope of this short 

 review. 



Edison succeeded in making incandescent 

 lamp filaments by carbonizing selected 

 strips of bamboo. But even a carbon made 

 of this unusually compact and uniform 

 material was far from being sufficiently 

 regular and homogeneous. Indeed, all the 

 then known forms of carbon conductors had 

 the fatal defect of a structural lack of 

 homogeneity. On account of this, the re- 

 sistance varied at certain sections of the 

 filament, and at these very spots, the tem- 

 perature rose to such an extent that it 

 caused rapid destruction of the filament; 

 this is somewhat similar to the chain which 

 is just as strong as its weakest link. 



These irregularities in the filament re- 

 duced enormously the term of service of 

 any incandescent lamp. "Weston tried to 

 solve this difficulty by means of his chem- 

 ical knowledge. He remembered that as a 

 boy, when he went to visit the gas works to 

 obtain some hard carbon for his Bunsen 

 cell, this carbon was collected from those 

 parts of the gas retort which had been the 

 hottest, and where the hydrocarbon gas had 

 undergone dissociation, leaving a dense de- 

 posit of coherent carbon. 



In this chemical phenomena of dissocia- 

 tion at high temperature, he perceived a 



