SOME NEW MODES OF LICIITING. 269 



it is concentrated l)y metal screens the heat i-isin<!: I'l-oiii tlie incan- 

 descent mantles. The vapoi'ized oil escapes (h)\vn\vard throu,<j:h a 

 large tube at the side of the himj) and here, mixing with ail- a(hnifted 

 through a heated chamh(>i', is led from beneath to the burners. 



The light of the two-biii-nei- Kitson lamp is (hiz/Iing and reaches 

 at least 1,000 candlei)o\ver. With specially favoi-able conditions, such 

 as with a new mantle and a high i)ressure of oil, 1,500 or even 2,500 

 candlei)ower is sometimes obtained. Oil is consumed at the rate of 

 about 0.2 liter (one-half pint) i)er 1,000 candlepower per hour. The 

 lio-ht produced has a mellow, agreeable color, nnich wai'uier in tone 

 than that of the electric arc or the incandescent gaslight. As already 

 remai'ked, the intensity depends on the pressure, which is an inconven- 

 ience for a lamp of small oil capacity, but where thei-e is a reservoir 

 of large dimensions the diminution of pressure during twenty-four 

 hours causes no considerable vai'iation in the intensity of the lamp. 



Of all methods of i)roviding intense light, these which have been 

 described are most economical. It is possible to combine in a single 

 system lamps of great and relatively small intensity, and the material 

 employed is connnon and inexpensive and may serve to i)roduce both 

 lighting and heating, or, indeed, motive power. There are no special 

 dangers to be feared when the combustible liquid is placed outside 

 the dwelling, and both the Washington and Kitson systems include 

 an autouuitic valve to close off the circulation in case of leakage. The 

 greatest ()l)jections are the use of licpiid which has a disagreeable odor, 

 tends to creep, and which sometimes yields a foul and disagreeable 

 smoke. Finally, the production of the gas from the li(]uid under 

 pressiu-e produces a noticeable roaring sound, l^ut for most pur- 

 poses these inconveniences are of minor importance as compared with 

 the great advantages of a superl) quality of light at minimum cost. 



No other mode of lightin.g can compare in cheapness with the 

 petroleum incandesci'ut lamj) in countries where kerosene nuiy be 

 bought at a cost of from 2 to 4 cents a liter (8 to lO cents a gallon). 

 It is just to add that in cases where natural gas or water power fur- 

 nishes an almost gratuitous source of energy the electric light may 

 indeed compare in cheapness, but even then there must first be ])ro- 

 vided complicated and costly nuichinery. 



Benzine is employed instead of petroleum in the Glitsch system, and 

 although somewhat more dangerous, this liquid is cleaner and in cer- 

 tain other respects more suitable for the purpose. It is unnecessary 

 to use pressure greater than 1 atmosphere to circulate benzine through 

 the capillary tubes, and the lamps may be fed by merely placing the 

 reservoir somewhat above them and depending on the force of gravity. 

 The metliod of starting combustion is very simple and ccmsists merely 

 in heating the burner for twenty or thirty seconds in an auxiliary 

 flame of alcohol in order to begin the vaporization of the benzine. 



