Memoir on Sulphuric Ether. AAQ 
mercury, by a diminution of temperature 
of 30°; then that of ether would be dimi- 
nished from 30 to 15 inches by the same num- 
ber of degrees, though in a much lower part 
of ‘the scale; the former being from 212° to 
182°, and the latter from 98° to 68°. Sub- 
sequent experience, however, led me to appre- 
hend that the above intervals of temperature, 
though expressed by equal expansions of 
mercury, are not in reality equal intervals ; 
but that equal intervals are rather denoted by 
the forces of steam being in geometrical pro- 
gression. Consistent with this view I found 
that steam from water and ether would con- 
cur, for a long range of temperature, with 
the difference of ratios only ; that of water 
being 1.321 for 10° of temperature, whilst 
that of ether was 1.2278. 
In the above work occurs the following ob- 
servation ; “ Ether as manufactured in the large 
way appears to be a very homogeneous liquid. 
I have purchased it in London, Edinburgh, 
Glasgow and Manchester, at very different 
times, of precisely the same quality in respect 
to its vapour.’ This observation, though war- 
ranted from my limited experience at the 
time, I now find not altogether correct ; 
I am sorry that it has occasioned an ingenious 
VOL, Ul. ull 
