32 
MINUTES OF PROCEEDINGS OF 
Insufficiency of 
vapourising 
process alone 
to protect a 
mass of gun¬ 
powder from 
explosion. 
Volatilisation of 
the sulphur 
partially 
effected when 
sufficient eleva¬ 
tion of temper¬ 
ature had been 
reached. 
Grounds for 
believing that 
there was no 
gradual or 
general eleva¬ 
tion of tempera¬ 
ture sufficient 
to account for 
explosion of 
powder. 
second was only partially so. It is quite clear, from tlie condition 
of the powder in the open barrel in No. 4 magazine, where the 
vapourising process was in active progress at the moment when 
the experiment was arrested, that no such complete saturation of 
a large mass of powder is to be looked for. If a quantity of 
powder, exposed for 22 hours to the full vapourising action of the 
alum is saturated only to the depth of from about -foih to Jth inch, 
it is clear that the non-explosion of the powder is not to be 
referred to this cause, nor can be secured in this way. The 
powder in canisters, also, was similarly only partially affected by 
the vapour. 
As to the volatilisation of the sulphur, there were—as detailed 
in Professor AbeTs memo. (Appendix P)—indications that some 
partial action of this sort had commenced in the only magazine in 
which the temperature was registered as that at which sulphur 
will volatilise. If the thermometer is to be relied upon, the 
temperature in magazine No. 1 did not rise above 212°, which is 
about 28° below the temperature at which sulphur melts. 
In the case of magazines 2 and 3, we have no means of forming 
an opinion whether the temperature did or did not rise to 240° 
(the explosions in those cases having been evidently due, as I shall 
show, to another cause), and the only powder recovered from 
these (the canister from No. 2) indicated no change in regard to 
its per-centage of sulphur. 
So No. 4 magazine is the only one which gives any reliable 
evidence on this point; and in No. 4 magazine the expectation 
that the sulphur would gradually disappear seems to have been 
partially realised. 
There remains, then, to be considered :—Why did Nos. 2 and 3* 
magazines explode at all ? Was the explosion due to a gradual 
and general elevation of temperature in the interior (in other 
words, to a gradual failure) of the magazine after the lapse of so 
many hours ? To this question I think a confident reply may be 
given in the negative, for the following reasons :— 
1. Gunpowder will not explode at a less temperature than 
about 560 . But there was recovered, as stated, from No. 3 
magazine, a stick of alloy with a melting point of 482°, and this 
stick was quite unaltered. Had the temperature of the interior 
of the magazine risen to the exploding point of powder (560°) the 
alloy must have been melted. 
2. There was recovered, as stated, from No. 2 magazine a 
canister of powder unexploded. Had the temperature of the 
magazine risen to the exploding point of powder, it is difficult to 
see how the powder in this canister could have escaped explosion. 
3. Several pieces of canisters were picked up with the solder 
unmelted—and solder melts at a lower temperature than 560°. 
4. We have the indirect evidence furnished by the observed 
temperatures in the two magazines which did not explode—viz., 
212° and 250°, according to the thermometers. 
