222 CAPTAIN NOBLE AND MR. F. A. ABEL ON FIRED GUNPOWDER. 
obtained by its explosion in 40 per cent, space (as given in Table III., page 215) with 
those in the general series (Tables I. and II.) furnished by the same powder, fired in 
the same space. In the one instance 22’87 per cent, of sulphate were found, in the 
other it was barely half that amount. With such variations occurring in the propor¬ 
tion of sulphate formed under like conditions of explosions, it can hardly be matter for 
surprise that variations of the same kind should occur in the proportions of sulphide 
and hyposulphite. In fact, in the two parallel experiments now referred to, the 
amount of sulphide contained in the residue rich in sulphate was only about one-fifth 
that contained in the other residue, the proportion in this being higher than any in 
the three series of analyses. Be it observed, at the same time, that this high amount 
cannot be ascribed to the adoption of any special precautions to prevent accidental 
oxidation of the sulphide in the special experiment in which it was found, as there 
were several residues in the series furnished by pebble powder (of the same composi¬ 
tion as the II. L. G.) which contained proportions of sulphide not much lower than in 
this particular case. 
Two other parallel experiments (39 and 96) with It. L. G. conducted in 60 per 
cent, space, exhibit, on the other hand, a remarkably close concordance in regard to the 
proportions of sulphate and hyposulphite (the numbers being almost identical), though 
there was a decidedly higher proportion of sulphide in the one than in the other, and 
a not unimportant difference in the proportions of the gaseous constituents. 
With regard to the results of the special experiment with pebble powder (p. 215) 
conducted in 40 per cent, space, and the parallel experiment in the series of pebble 
powder results, it will be seen that the amounts of sulphate formed in the two experi¬ 
ments were closely similar. The proportions of sulphide and hyposulphite found in the 
residue of the special experiment correspond very well with the results obtained with 
this powder at the two lower and the next higher densities, which is not the case with 
the parallel experiment in the series (No. 12, 40 per cent.), and this may possibly 
indicate that, in the latter, there may have been an exceptionally considerable con¬ 
version of sulphide into hyposulphite during the removal of the residue from the 
ex plosion-vessel, it being borne in mind that marked differences in the behaviour and 
appearance of the residues (even those resulting from the service powder) were 
frequently noted at the time of collection. 
Before leaving this part of our subject we may remark that we have placed in the 
appendix to this memoir a statement in which we have given for every analysis we 
have made, the results of the following rather laborious calculations, which have been 
made in the manner described in our first memoir. * 
(1) The amount of gaseous products calculated from the data furnished by the 
analysis of the solid products. 
(2) The amount of solid products calculated from the data furnished by the analysis 
of the gaseous products. 
* Phil. Trans., 1875, Part I., p. 90, 
