58 
MINUTES OF PROCEEDINGS OF 
But in almost every instance, the charcoal will be found a little below, 
and the sulphur a little above the figures given; probably caused by 
the fact that charcoal always contains a certain quantity of moisture, 
for which no allowance is made when weighing out the ingredients. 
The question as to the best proportion of the ingredients, is one which 
cannot be too soon taken up by the Committee on Explosives. 
VII. Hygroscopic test.— This, like the analysis, has recently been 
conducted in the Chemical Department. It consists merely in subjecting 
dried specimens of powder to a damp atmosphere, in a closed box, kept 
at a uniform temperature, and weighing them at regular intervals, to 
ascertain the rapidity with which they absorb moisture. Powders are 
found to vary very much in this respect. Generally speaking, a hard 
texture is unfavourable to absorption; a highly burnt charcoal also 
renders the powder less absorbent of moisture than a less burnt, and 
consequently less dense one. As a rule, contract powder—of which the 
charcoal is generally under-burnt—absorbs about twice as much as 
Waltham Abbey powder. The density of the powder affects the results 
to a considerable extent—at least with black charcoal powder, the 
absorbing power of which is diminished as its density is increased; but 
the comparatively high absorbing power imparted to the powder by 
red charcoal, is little if at all reduced by an increase of density. The 
quality of non-absorption of moisture, is of course a most important one 
for powders to possess. 
Having now gone over all the proofs to which gunpowder is subjected, 
it may be as well to show the form in which the results of examination 
and proof are recorded at Waltham Abbey. 
The following is a copy of the heading of the proof-book of R.L.G. 
powder, with an entry. Similar books are kept for all other powders :— 
Proof of P.L.G ., manufactured at Waltham Alley . 
Date of 
stoving. 
No. of barrels 
in stoving. 
Remarks on 
flashing. 
Sifting of 16 lbs. 
Density. 
Analysis; 
In 100 parts of dry powder. 
Moisture; 
4 to 6 
6 to 8 
pass 8 
Saltpetre. 
Sulphur. 
Charcoal. 
- 
35 
very clean 
lb. oz. 
12 2 
lb. oz. 
3 10 
lb. oz. 
0 4 
1*680 
75*51 
10*01 
14*48 
0*90 
( Continued .) 
Thermo* 
Velocity of 121b. shot at 
Date of 
firing proof. 
1 
meter. 
105'. Charge lib. 
4) 
8*1 
Remarks. 
g 
*4 
1 Wet 
bulb. 
cS 
n 
1 
2 
3 
Mean. 
S £ 
- 
30'*12 
60° j 
1 60° 
ft. 
1002 
ft. 
1000 
ft. 
1007 
ft. 
1003 ' 
’ 1007*8 
