ON EXPLOSIONS IN CHEMICAL LABORATORIES. 251 
into another. The naphtha was kept in a cellar, in a large 
tin bottle ; but this being at the time of the accident only 
about a quarter full, its contents was poured into a smaller 
bottle, in the immediate vicinity of which was a burning 
candle. The oil ignited with such a violeut explosion, that 
the tin bottle burst, and the burning naphtha was thrown 
about the place. In this case, probably, the cellar had not 
been kept sufficiently cool, or the burning candle had been 
standing for some time close to the tin-bottle, so that the 
vapour of the volatile oil mixing with the atmospheric air 
contained in the bottle, formed an explosive mixture. A 
case is known where a spirit of wine cask which was not 
quite empty, and which had been for some time exposed to 
the sun on a hot summer's day, had an explosive mixture 
formed within it, and which took fire on the approach of a 
candle. 
Before the introduction of Woulfe's apparatus into phar- 
maceutical laboratories, explosions during distillations were 
of more frequent occurrence than at present. In distilling 
liquor ammoniac, two accidents are known to have occur- 
red, by one of which the operator lost the sight of both his 
eyes. Another happened in distilling concentrated acetic 
acid, in consequence of the junction of the receiver with the 
retort having been made air-tight by a bladder, and the re. 
ceiver not being kept sufficiently cool. 
A violent explosion once took place in a pharmaceutical 
laboratory, when some organic substance was subjected in 
a retort to decomposition and distillation with nitric acid. 
In order to explain the phenomenon, it is only necessary to 
call to mind the properties of xyloidin and of gun-cotton. 
In the laboratory of Professor Trommsdorff, four dangerous 
explosions took place in thecourse of a few years. The one 
happened with the purple of Cassius. The precipitate of 
gold had been collected on a small filter, washed, and placed 
on a stand near the heated parlor-stove, where it remained 
for some weeks. Mr. Trommsdorff then introduced the pre- 
