382 Dr. ingenhousz’s Account of a 
which from their lefs fpecific gravity efcape eafily into 
the common air, yield an offeiriive, difagreeable flench. 
• Mr. aeneae, having examined the fpecific gravities 
of the different inflammable airs compared with com- 
mon air, favoured me with the following refult of his 
inquiries. 
A veffel, which contained the weight of 138 grains 
of common air, contained 25 grains of inflammable air 
extracted from iron by vitriolic acid, and 92 grains of in- 
flammable air extracted from mud or marfhes, and 150 
grains of that extracted from oil of vitriol and fpirit of 
wine. 
I was much pleafed with the above mentioned experi- 
ment, and immediately thought that the operation of 
extracting this inflammable air or vapour could be dif- 
penfed with by employing vitriolic tether, which in 
reality is contained in the vapour expelled by heat from 
oil of vitriol and fpirit of wine, which vapour, condenfed 
in the procefs of diflillation, yields aether. But I re- 
folved to defer making the experiment till I fhould ar- 
rive in London, where I intended to make fome flay 
to fee my old friends, and acquire what medical and phi- 
lofophical knowledge I could. 
Having arrived, in this capital in the beginning of Ja- 
nuary 1778, I loft no time in purfuing my idea. For 
4 this 
