402 Dr. Crawford's ’Experiments on the Matter 
water with which the air had been agitated, the mixture in- 
ftantly acquired a reddifh brown colour ; after fome time it 
became turbid, and a brown precipitate fell to the bottom. 
When two meafures of the air, extricated in this experiment, 
were mixed with one of alkaline air, they occupied the fpace 
of a little more than one meafure and an half. A fecond 
mcafure of alkaline air being added, and the airs being buffered 
to remain together for three days, at the end of that time the 
re fid ue occupied the fpace of two meafures and one-eighth. 
Soon after they were mixed, an oily fluid, of a pale colour, 
was depofited on the internal furface of the jar. At the end 
of the third day this fubftance had acquired a light olive 
colour. It was collected in globules, irregularly diftributed 
over the interior furface of the jar. Thele globules were 
nearly of a folid confiftence. When the jar was removed from 
the mercury, the air contained in it at firft fmelled ftrongly of 
volatile alkali. After a littie time the fined of the alkali 
difappeared, and the odour of empyreumatic oil was difiindtly 
perceived- A fmall quantity of difiilled water, which was 
now agitated in the jar, acquired a brown colour, but did not 
entirely diffolve the vifcid fubftance that adhered to its furface. 
I he water, tnus coloured, was Giviaed into two portions. To 
one of thefe was added a little ftrong vitriolic acid, by which 
the fmell was exalted, and a flight effervefcence was produced. 
Concentrated nitrous acid being added to the other portion, the 
fmell and colour were deftroyed, and a brifk effervefcence took 
place. 
When a portion of the folid fubftance that adhered to the 
interior furface of the jar was feparated, it felt vifcid and 
adhefive between the fingers, and fmelled ftrongly of empy- 
leumatic oil. A little fpirit of wine being introduced into the 
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