ON LIGHTS. 69 



burned steadily and did not consume the wick. The rosin light (No. Ij 

 was yellowish, approaching to that of a candle ; it gave rather more 

 light than No. 2, but burned as if the wick had been slightly moistened 

 and left a crust upon it. No. 3 was paler than No. 2, but similar in 

 other respects. 



To ascertain the relative economy of these lights it is necessary to 

 compare them all with some uniform standard •, for this purpose the ex- 

 pense of burning for 100 hours has been taken, 133 ounces by measure 

 have been allowed to a gallon, and the calculations made at the follow- 

 ing prices: Turpentine 75 cents per gall., Alcohol 75 cts., Sperm oil 

 $1 25, Camphor 75 cts. per lb., Rosin 4 cts., Candles 10 cts., Lard 

 10 cents. 



From the above data it has been found that 



No. 1 costs 72 cents per gall, and 1 gallon burns 313 hours. 



2 " 100 " " 2(36 " 



3 " 75 « " 233 '' 



4 " 1.25 " " 511 " 



Expense of light for 100 hours, 



From these experiments it appears, that the alcoholic preparations 

 with the exception of No. 1, are in fact dearer than oil, although the 

 cost per gallon is much less, and that they consume more rapidly and 

 give less light. They are very combustible, and those who use them 

 are liable to accidents from this cause. Candles are cheaper than sperm 

 oil and lard ; with equal light about the same as candles. 



Turpentine alone emits too much smoke, and the same is true when 

 mixed with the fixed oils or lard. Wax and Indian rubber, not being 

 soluble in alcohol, have not been used. 



Lard oil will probably soon be brought into general use as a substi- 

 tute for sperm; its fluidity renders it as well adapted to the production 

 of light, and it will, no doubt, be furnished at less expense. 



H. H. 



