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MINUTES OF PROCEEDINGS OF 
of silk. The investigation lias not yet proceeded far enough to warrant any 
detailed account of the experiments being given—that must be reserved 
for a future occasion; but it may be worth while to state that, so far 
as the inquiry has gone, it seems to show that the risk in gunpowder 
buildings is in no degree diminished, but rather the contrary, by the use 
of silk-waste. Mr. Galletly writes :—“ A little powder in the centre of 
silk waste ignited in an hour, while a little amongst the cotton did not 
ignite for an hour and a half. On the other hand, the cotton reached 
actual incandescence in about the hour and a half, whilst the silk was 
merely charred, and indeed never got red hot at all.” 
In a subsequent letter, Mr. Galletly says :—“ I have put up silk and 
cotton-waste to-day at 2 p.m., with boiled linseed oil—chamber at 
120° Fahr. Silk exploded gunpowder at 4.10 p.m., and cotton not yet, 
(5.20 p.m.) ” 
Mr. Bloxam observes, with regard to these results 
“ Rumford found, for the times of equal cooling, in 
Sewing silk . 917 
Lint . 1032 
Cotton . v ... 1046 
Wool . 1118 
Raw silk . 1284 
“ The conducting powers would of course vary inversely as these 
numbers. It might therefore be expected that the inside of the mass 
of silk-waste would become hotter in a given time than the cotton-waste, 
which would conduct the heat more rapidly outwards. As to the 
charring, cotton is of course, in itself, a more inflammable material than 
silk, so that I should expect it to take fire at a temperature which would 
only suffice to carbonise the silk. ..... The powder would of 
course fire as soon as a definite temperature was reached, whether the 
material around it actually inflamed or not.” 
Mr. Bloxam also suggests that possibly as “ the oil would soak more 
thoroughly into the cotton than into the silk, the latter being merely 
varnished over with oil, would expose more on the surface to the 
oxidising action of the air, and would therefore heat more readily, though 
it would not inflame, on account of the want of inflammability of the 
silk itself. ” 
The conclusions are clear - 
(1) That oiled waste, whether of silk or cotton, should invariably be 
regarded with suspicion, as liable to spontaneous ignition under 
moderately elevated temperatures. 
(2) That silk waste is at least as dangerous as cotton, or even more 
so, in a building containing gunpowder, or other material which is 
capable of being ignited or exploded without the actual application of 
flame. 
Home Office, Whitehall, S.W., 
Tfuavi ary 1873. 
V. D. M. 
