104 
CAPTAIN NOBLE AND ME, E. A. ABEL ON EIEED GUNPOWDER. 
Table VIII. — Showing the comparison, in atmospheres and tons per square inch, between 
the pressures actually observed in a close vessel and those calculated from the 
f i (1 — «S 0 ) & 
formula p=p, — 
1 . 
Density of pro- 
ducts of com- 
bustion. 
Value ofp 
deduced from 
direct observa- 
tion. 
3. 
Value of p 
deduced from 
equation (3) when 
a=-65. 
4. 
Value of p 
deduced from 
equation (3) when 
a -60. 
5. 
Value of p 
deduced from 
direct observa- 
tion. 
6. 
Value ofp 
deduced from 
equation (3) when 
«=-65. 
7. 
Value of p 
deduced from 
equation (3) when 
«= 6. 
Tons per 
square inch. 
Tons per 
square inch. 
Tons per 
square inch. 
Atmospheres. 
Atmospheres. 
Atmospheres. 
•05 
0-70 
•758 
•855 
107 
115 
130 
•10 
1-47 
1-565 
1-765 
224 
238 
269 
•15 
2-33 
2-432 
2-734 
355 
370 
416 
•20 
3-26 
3-363 
3-771 
496 
512 
574 
•25 
4-26 
4-367 
4-879 
649 
665 
743 
•30 
5-33 
5-452 
6-071 
812 
830 
924 
•35 
6-49 
6-628 
7-350 
988 
1009 
1119 
•40 
7-75 
7-908 
,8-732 
1180 
1204 
1330 
*45 
9-14 
9-305 
10-228 
1392 
1417 
1557 
•50 
10-69 
10-837 
11-851 
1628 
1650 
1805 
•55 
12-43 
12-524 
13-620 
1893 
1907 
2074 
•60 
14-39 
14-390 
15-554 
2191 
2191 
2369 
*65 
16-60 
16-466 
17-679 
2528 
2507 
2692 
•70 
19-09 
18-791 
20-024 
2907 
2861 
3049 
•75 
21-89 
21-410 
22-625 
3333 
3260 
3445 
•80 
25-03 
24-383 
25-525 
3812 
3713 
3887 
•85 
28-54 
27-789 
28-780 
4346 
4232 
4383 
•90 
32-46 
31-728 
32-460 
4943 
4831 
4943 
•95 
36-83 
36-336 
36-654 
5608 
5538 
5582 
1-00 
41-70 
41-698 
41-477 
6350 
6350 
6316 
Now if the figures given in columns 2 and 5, being those derived from the obser- 
vations themselves corrected by differencing, be compared with the values given in 
columns 3 and 6, computed on the value a = -65 (that is, on the assumption that at the 
temperature of explosion the liquid residue of 1 gramme of powder occupies -65 cub. 
centim.), it will be found that the two columns are practically indentical, thus affording 
a confirmation of the strongest nature of the correctness of our assumption. The close- 
ness of agreement will he best seen by examining the graphical representations in 
Plate 17. We have already, however, had more than once occasion to remark that there 
is reason to suppose that the observed pressures are slightly in defect, at all events at 
low densities. Other considerations have led us to the conclusion that a value of a 
not far removed from ’6 would more nearly represent the truth, were all disturbing 
influences removed. We have therefore added to the above Table the pressures com- 
puted on this hypothesis ; and Plate 17 shows at a glance the comparison between the 
three curves. 
0. DETERMINATION OP THE TEMPERATURE OF EXPLOSION OP GUNPOWDER, 
We are now in a position to compute the temperature of explosion. 
