[ 2I 3 3 
tfic courfe of it, the greater is the diminution. I 
have even reduced pieces of wood to little more than 
one fourth of their original length and breadth, in a 
common fire, by the ufe of a pair of hand bellows 
only. And this was the cafe equally with wood of 
the firmed: texture, as ebony; that of a middle tex- 
ture, as oak ; and that of the loofeft, as fir, &c. 
As moifture, and, 1 believe, fmall degrees of heat 
or cold, affe&s wood much more fenfibly acrofs the 
fibres than along them, it might have been fuppofed, 
that when wood was reduced to a coal, by the ap- 
plication of a greater degree of heat, the fame rule 
would have been obferved ; but I found very little 
difference in this refpeCt. To afcertain this circum- 
fiance, [ took, from the fame board, two pieces, each 
2 | inches in length. In one of them, the fibres 
were divided, in the other they were not; and after 
coaling them thoroughly together, in the fame 
crucible, 1 found that the former meafured 2.05 
inches, and the latter 2.15. Their conducting power 
could not be diftinguifhed. 
A more particular account of the degree, in which 
wood is fhortened in coaling, will be feen afterwards, 
when the variations in this refpect are compared with 
the variations in the power of conducting electri- 
city. 
To my great furprize, I found animal fubftances 
not reduced in their dimenfions by the procefs of 
coaling. This, at leaft, was the cafe with fome 
pieces of ivory, feveral inches in length, and a piece 
of bone. They bore a very intenfe heat for many 
hours, and came out of the crucible confiderably 
diminifhed in weight, but hardly fo much as di- 
fiorted 
