82 
CAPTAIN NOBLE AND ME. E. A. ABEL ON EIEED GTTNPOWDEE. 
carbonate are somewhat considerable ; the proportions of sulphate were, on the other 
hand, much alike, except at the highest and lowest pressures. The proportion of hypo- 
sulphite was generally high, and that of the sulphide low, as compared with the pro- 
portions of these constituents in the other powder-residues just discussed. In two of 
the residues from F. G., the proportion of sulphur Avhich did not enter into the principal 
reactions is about the same as that found in the pebble-powder residues ; while in three 
others only small quantities of free sulphur existed — in two of these there was free 
potassium oxide. Two of the residues (Nos. 42 & 47) contained not a trace of potas- 
sium sulphide discoverable by the most delicate test (sodium nitroprusside). 
With respect to the proportions of potassium sulphide and potassium hyposulphite 
found in the several residues analyzed, the following points appear to be worthy of 
note. 
1. In the residues obtained by exploding pebble, K. L. G., and F. G. under the lowest 
pressures (the charges only occupying 10 per cent, of the total space), the proportion 
of potassium hyposulphite is in all cases high, while that of the sulphide is corre- 
spondingly low. 
2. In the comparatively slow-burning pebble powder, the products of explosion of 
which at different pressures exhibited great similarity in many respects, there is a 
marked fluctuation in the proportion of hyposulphite ; and this corresponds to a fluctua- 
tion, in the opposite direction, in the amount of sulphide found, while the sulphate 
varies but little. A similar fluctuation and relation is observed, as regards these two 
constituents, in the solid products of the experiments made with It. L. G. powder at 
the lowest pressures, but not, or only to a slight extent, in the residues furnished by 
the powder at higher pressures. 
3. In most of the residues from F. G., the hyposulphite is large in amount and the 
sulphide small : in two of these (Nos. 42 & 47), which did not contain a trace of 
potassium sulphide, the proportion of hyposulphite was considerably higher than in 
any of the other experiments*; and in these cases there was no free sulphur — that is to 
say, no sulphur in the form of poly sulphide, the small proportion given under the head of 
“ sulphur ” in the tabulated results being found in combination with iron derived from 
the interior of the chamber. 
The circumstance that the hyposulphite generally existed in large proportions when 
the sulphide was small in amount, appeared at first sight to afford grounds for the 
belief that its production might be ascribable to a secondary reaction resulting in the 
oxidation of sulphide by carbonic anhydride, a view which might appear to receive 
support from the following circumstance. The upper portion of the solidified mass in 
the cylinder was found to contain a considerably larger proportion of hyposulphite 
than the remainder, as is demonstrated by the following results of a separate examina- 
tion of the top and the lower portion of the residues obtained by exploding a charge 
* One residue furnished by P. powder (experiment 38) contained a similarly high amount and a very small 
quantity of sulphide. — February 1875. 
