probable cause.

By means of direct experiment we are also learning something on the
question of explosions. It used to be assumed that gunpowder was
answerable for all such terrible effects in warehouses where no gas or
steam was employed; and as policies are vitiated by the fact of its
presence, unless declared, many squabbles have ensued between insurers
and insured upon this head alone. At the late great fire at
Gateshead, a report having spread that the awful explosion which did
so much damage arose from the illicit stowage of seven tons of
gunpowder in the Messrs. Sisson's warehouse, the interested insurance
companies offered a reward of 100l. to elicit information. The
experiments instituted, however, by Mr. Pattinson, in the presence of
Captain Du Cane, of the Royal Engineers, and the coroner's jury
impanelled to inquire into the matter, showed that the water from the
fire-engine falling upon the mineral and chemical substances in store
was sufficient to account for the result. The following were the
experiments tried at Mr. Pattinson's works at Felling, about three
miles from Gateshead.

"Mr. Pattinson first caused a metal pot to be inserted in the ground
until its top was level with the surface; and having put into it 9
lbs. of nitrate of soda and 6 lbs. of sulphur, he ignited the mass;
and then, heating it to the highest possible degree of which it was
susceptible, he poured into it about a quart of water. The effect was
an immediate explosion (accompanied by a loud clap), which would have
been exceedingly perilous to any person in its immediate vicinity.
The experiment was next made under different conditions. The pot into
which the sulphur and nitrate of soda were put was covered over the
top with a large piece of thick metal of considerable weight; and