On the Cofl of Illumination hy different KinJs of Candles. ' 191 



We may now from the preceding refults, founded on experience, draw the following 

 conclufions : 



a) That in general' tallow candles of a fmaller diamdter are confumcd more fparingly 

 than thicker ones. 



h) That the reafon of this pfiaenomenon muft be fought for in the mafs of tallow, which 

 being too' great in thick candles, is Reated at once, and thus volatilized without burning 

 like the fat in roafting meat; for which reafon, 



c) Since a fufficient quantity of oxigen gas from the atmofphere cannot then a£l upon it, 

 but only on the exterior part of the flame, a great part of the combuftible matter muil be 

 loft in thefe vapours; at the increafing intenfity of heat, without decompofing the air in 

 order to extricate light by burning.— But this oil the other hand, 



d) Cannot be the cafe with thinner candles, becaufe much lefs of fuel is loft, and alfo 

 becaufe in that cafe lefs of tallow is neceflary to be confumed, in order to produce the fame 

 quantity of light as is afforded by a thicker candle : for in this cafe more of oxigen gas is 

 decompofed, and more free light feparated, which alfo 



e) Affords this great advantage, that fuch a candle produces lefs vapour and foot, be- 

 caufe the fuel being then more effedually confumed, will be volatilized, and go off as foot 

 in an uridecompofed ftate in a much lefs' proportion. 



But candles would afford the brighteft and pureft light, which have a broad, ribbon-like 

 wick inftead of a round one, or to which the form of hollow cylinders were given, fo that 

 the air might adt upon the flame inwardly as well as outwardly. For by an arrangement 

 of this kind all the combuftible matter will be confumed, and no fmoke nor foot, but 

 merely water and carbonic acid gas can be formed, as muft be evident to every one ac- 

 quainted with the principles of chemiftry. But to fuch as are not chemifts, Argand'3 

 lamp may ferve as a proof. At the fame time it is equally evident from the preceding 

 theory or explanation, that every flame, which is not"obfcured by foot, muft afford a 

 ftronger light than another in oppofite circumftances ;and it is equally obviousv that fuch, 

 a flame, from the total abfence of fmoke and foot, cannot emit any unpleafant odour. I 

 intend to inftitute further experiments on this fubjeit, and to commtihicate thehvat a 

 future time. 



Laftly, I have alfo endeavoured to afcertain the intenfity of light emitted by the various 

 forts of candles here mentioned. For this purpofe the lighted candle was placed upon a 

 table in a room totally dar-kened. I then, holding a book in the hand, withdrew back- 

 wards, until the characters became invifible to my eyes. The feveral diftances from the 

 luminous cone were accurately meafured, and afforded the following refults : 



The wax candle (Experiment I.) emitted light, of which light the illuminating diftancc 

 was 10 feet, 1 inch, 6 lines Rhinland meafure *. 



* A Rhinland foot is equal to about 1 foot and 3-10th8 of an inch Englifli meafure.— A line is one- 

 twelfth of an inch,— Tranil, 



The 



