94 Count Rumford’s Enquiry concerning the Nature of Heat , 
upon the eighth coating of the varnish,) and, repeating the ex- 
periment, its results were as follows. 
Time employed in 
cooling through the 
given interval. 
The instrument No. 1, naked - 55^ min. 
Instrument No. 2, covered with 8 coatings of] 
varnish, and painted black J mm * 
Exper. No. 9. Finding that the painting of this thick coating 
of varnish black, rendered the covering still colder, or accelerated 
the cooling of the instrument, I now washed off the black paint, 
with warm water; then, washing off all the varnish with hot 
spirit of wine, I painted the metallic sides of the instrument 
of a black colour, with lamp-black and size; and, when the 
paint was quite dry, I repeated the experiment so often men- 
tioned ; yvhen the results were as follows. 
Time employed in 
cooling through the 
given interval. 
The instrument No. 1, sides naked - - 55^ min. 
No. 2, painted black 35 min. 
Exper. No. 10. In order to find out whether the black colour 
had any particular efficacy in expediting the cooling of the in- 
strument, or whether another colouring substance would not 
produce the same effect, when mixed up with the same size, I 
now washed off the black paint, and painted the sides of the 
instrument white , with whiting mixed up with size; and, on 
repeating the experiment, the results were as follows. 
Time of cooling through 
the given interval. 
The instrument No. 1, naked - 553- min. 
No. 2, painted white 36 min. 
As, in both the two last experiments, it was found necessary 
