358 Dr. Ure's new experimental researches 
through a much more extensive range, than the elaborate 
formula of the distinguished French geometer. Even when 
carried so high as the 310th degree of Fahr., we have 
Log. 28.9 n. log. r = 2.19810 = L, F joo ; hence 
F soo = 3 57-8 
Experiment gives 161.3, a difference of only 3I inches 
at this prodigious elasticity; which may be deemed altogether 
unimportant in practice. 
Biot's formula gives a result 31 inches, and Mr. Dalton’s 
40 in defect. 
Of Professor Robison's higher numbers, it is merely 
necessary to examine the successive differences for every io° 
above 212°. These are 7.2, 8.9, 10.2, 11.9, 13.5, 13.8, n.8, 
and the second differences are -f 1 -7 + 3-3 4* 1.7 -f- *•*> 
+ 0.3 — 2.0. 
Such striking irregularities cannot exist in the progression 
of nature. Betancourt’s are liable to a similar censure. 
We may find indeed small discrepancies in the best observa- 
tions at such temperatures. 
§ II. Experiments to determine the elastic forces of the vapours of 
alcohol , ether, oil of turpentine , and petroleum or naphtha. 
The determination of the elasticities of these vapours is a 
very interesting problem in chemical philosophy. It may 
possibly unfold the law which connects temperature and 
elastic energy, and it may furnish likewise some useful 
applications. 
Mr. Dalton has examined the subject with considerable 
care. 
