296) Researches upon the Heat developed 
** The coloured, circles, immediately -surrounding ; the 
shadows of the observers, may be deduced from, the. effect 
of the same minute particles of water, upon the light which 
has been four, and perhaps five, times reflected,.within the ; 
drops, which may, after transmission, coincide in direction 
with another portion, passing on the opposite side of the 
centre ; and the drops about 5;!,5 or ¢goq of an inch in dia- 
meter would in this manner produce a faint corona, of such 
magnitude, that the limit of green and red, employed in 
the use of the eriometer, should be at the distance of about 
five degrees from the centre of. the shadow ; which, as 
nearly as I could estimate it, was its real distance in the 
appearance that I observed.” 
LI. Researches. upon the Heat developed in. Combustion, 
and in the Condensation of Vapours. Read before the French 
Institute on the 24th of February and 30th of November 
1812. By Count Rumrorp, F.R.S. Foreign Associate 
of the Imperial Institute of France, Be, 8c. 
[Continued from vol. xli, page 444.] 
§ VII, On the Quantity of Heat developed in the Com- 
) tustion of Naphiha. ; ) 
Taz naphtha which I made use of in my experiments 
was supplied by.M. Vauquelin: it had been purified by 
distillation, and its specific gravity at the temperature of 
56° F. was 82°731. : 
The following are the details and results of two experi- 
ments made with this liquid on the 29th of January 1812. — 
_.The capacity of the calorimeter for heat was equal to that 
of 2781 grammes of water. 
rin De- 
re] 
Oo 
wn 
i= 
eo 
perature 
Ibs.of Water heated 180° 
with 1 tb. of this Sub- 
grees of Fahrenheit. 
stance. 
Duration of the Experiment 
Quantity of Naphtha burned. 
of the Calorimeter i 
Elevation of the Tem 
M. S.|Gram. Deg. F. 
Ist Experiment .. .| 32 |4:45| 16 | 73°8811. 
2d Experiment ., .| 36 |2°77| 123 | 72°771 
Mean Result .. . 73°376 
