28 
MINUTES OF PEOCEEDINGS OF 
Detail of 
experiments. 
That is to say, the water, instead of being present in the shape of 
water, exists as water of crystallisation in the alum—which is, in fact, 
composed of about half its weight of water. On heat being applied, 
the water escapes as steam, through a number of fine holes, into 
the interior of the safe, wetting the contents, and at the same time 
keeping the interior comparatively cool. The patentees claim in their 
specification “ the exclusive use of any matter or thing evolving 
moisture on the application of heat.” The principle of action— 
whether alum or any other similar material be employed—is the 
same. It consists in keeping down the temperature of the interior 
by vapourisation, and at the same time, by wetting the contents, 
rendering them less liable to injury by fire. Some experiments 
on a small scale had previously been made to test the applicability 
of this principle to the preservation of gunpowder from explosion 
by fire. It was believed that the steam preceding the inroads of 
the fire would so completely saturate the powder as to destroy its 
explosive properties; and the results of such experiments as had 
been carried out appeared to confirm these expectations. 
However, no experiments of sufficient importance to warrant a 
confident recommendation of these safes as gunpowder magazines 
had been made, nor had the question been investigated as to how 
far the advantage of the vapourising principle would be neutralised 
if the powder were in hermetically closed canisters or cases—such 
as are generally used for sporting powder. 
In order to elicit full information on these points, I determined 
to arrange the experiments as follows :— 
Magazine No. 1 (designed to resist six hours) had placed inside it 
a small pinch of powder wrapped in paper, and six tin canisters, each 
containing about drms. (or about a rifle charge) of sporting 
powder. The canisters were closed in the usual way. To ensure 
the powder being distributed at different parts of the magazine, I 
caused the magazine to be filled with empty canisters, placing 
those which contained powder at different parts of the heap. The 
object of placing only small quantities of powder in this magazine 
was to enable it to be opened (for the satisfaction of the spectators) 
at the end of the six hours, without danger. 
Magazine No. 2 (designed to resist six hours) contained 10 lbs. of 
powder, in ten 1-lb. canisters, supplied by Messrs. Curtis and 
Harvey, Hall and Son, Pigou and Wilks, and Lawrence and Son. 
The canisters, which were of the sorts usually sold, and of mixed 
shapes and various constructions, were put in unopened; and, as 
in Magazine No. 1, were disposed at different parts of the interior. 
Magazine No. 3 (designed to resist six hours) contained 25 lbs.-of 
powder in an ordinary wooden powder-barrel, “ quarter ” size, and 
“ headed-up.” The powder was the sporting powder emptied from 
twenty-five 1-lb. canisters of various makers. The barrel was 
placed upon two bricks in the interior of the case, so as to occupy 
a position as nearly as possible in the centre of the magazine. 
Magazine No. 4 (designed to resist eight or nine hours) contained 
