Obfervations in Ele&ricity. 137 
in their pneumatical refearches (that produced from the 
calces of metals perhaps excepted) are only phlogiftic 
vapours arifing from, and partaking of, the qualities of 
the fubftances from which they are difengaged. 
“ The vapour of fermentation is much more fubtle 
“ than common air, it pafles through bodies which 
“ would be impenetrable obftacles to the latter. 
“ Mr. de smeth was not able to retain it by the aid 
“ of lutes : a moiftened bladder, tied over the mouth of a 
“ velfel which contained fome fermenting matter, was 
“ not at all inflated during the height of fermentation. 
“ Dr. Priestley has obferved, that the fixed air from 
“ fermenting beer combines eafily with the vapour of 
“ water, as alfo with the fmoke of rofin, fulphur, and 
“ other electrical fubftances. 
“ If it were permitted me to indulge in conjectures, I 
“ fhould fay that fome experiments induce me to be- 
“ lieve, that every elaftic fluid refults from the combina- 
u tion of fome folid or fluid body with the inflammable 
“ principle, or perhaps even with the matter of pure 
“ fire; and that on this combination the ftate of elafti- 
“ city depends.” See henry’s tranflation of M. Lavoi- 
sier’s Effays, phyfical and chemical. 
Mr. lane, in his curious and moft important experi- 
ment of diffolving iron in water impregnated with fixed 
Vol. LXVII. T air. 
