484 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



weight burned quicker in a painted lantern than in an nncoated 

 lantern, both alike exposed to the sun. 



These experiments did not find acceptance with Gmelin, and did 

 not appear in the original Handbook of Chemistry, doubtless from 

 a conviction that some error must have occurred either in the 

 method or record of observation. Nevertheless, Dr, McKeever's 

 experiments appear as atlditions in the Cavendish Society's trans- 

 lations of the Handbook. The summary of his results may be 

 stated thus : It required eleven minutes to burn in the sunshine 

 the same weight of candle that burned in the dark in ten minutes. 



Similar experiments were made at a later period by Dr. Morrill 

 Wyman, of Cambridge, and reported to the American Academy 

 of Arts and Sciences. The result at which be arrived was exactly 

 the reverse of that reached by Dr. McKeever. He burned two 

 sperm candles, each alternately for half an hour in the sunshine 

 and in darkness, and found the candle during its exposure to sun- 

 shine burned more rapidly than when in the dark. 



In 1856, the subject was taken up by Prof. Joseph Le Conte, of 

 Columbia, S. C. He concentrated, with the aid of a reflector and a 

 burning glass, the sun's rays upon the jiame only of a wax (sperm) 

 candle in a large dark room. At the sanae time another candle 

 was burning in the same room, under identical circumstances, 

 except that the flame was not exposed to the sun's rays. The 

 result showed that the effect of the sun's rays, though greatly 

 exaggerated by concentration, when confined to the flame, did not 

 appreciably increase the consumption of tallow. 



Here then we have apparently all possible results of experi- 

 ment ; to wit : sunshine diminishing the rate of combustion a» 

 observed by Dr. McKeever, augmenting the rate as observed by 

 Dr, Wyman, and producing upon it no eflTect whatever as shown 

 by Prof. Le Conte. 



Dr. McKeever ascribed the retardation to some peculiar effect, 

 as of interference of the solar ray upon flame. 



Dr. Wyman inferred that the sunshine by warming the tallow 

 of the candle exposed to it, facilitated its melting and by so much 

 spared for destructive distillation and combustion, the heat of the 

 flame, which would have otherwise, in larger measure, gone to 

 liquify the tallow, 



Le Conte conclusively showed that when the column of wax or 

 tallow is sheltered and the sunshine directed solely on the flame, 



