CAPTAIN NOBLE AND MR. F. A. ABEL ON FIRED GUNPOWDER. 
71 
E. COMPOSITION OF THE GUNPOWDERS EMPLOYED. 
The method pursued in determining the proportions of proximate constituents in the 
samples of gunpowder present but very few points of difference from those ordinarily 
adopted, and need therefore not be detailed. 
It may he mentioned, however, with reference to the determination of the proportion 
of saltpetre, that a very appreciable amount of the most finely divided particles of the 
charcoal generally passes through the filter during th'e final washings, however care- 
fully the operation be conducted. 
These last washings, which contain ‘only a very small proportion of the saltpetre, were 
therefore evaporated separately, and the residue was carefully heated until the small 
quantity of charcoal was completely oxidized. The resulting carbonate was then con- 
verted into nitrate by careful treatment with dilute nitric acid, and the product added 
to the remainder of the saltpetre previously extracted. 
The composition of the charcoal contained in the powders was determined by com- 
bustion, after as complete a separation of the other constituents as possible. There 
was, of course, no difficulty in completely extracting the saltpetre ; but the sulphur 
cannot be entirely removed from the charcoal by digestion and repeated washings with 
pure carbon disulphide. The amount remaining was therefore always determined by 
oxidation of the charcoal, and estimation of sulphuric acid produced ; the necessary 
correction thus arrived at was made in the amount of charcoal used for analysis. 
The latter was dried by exposing it for some time (in the platinum boat in which it 
was to be burned) to a temperature of about 170° in a current of pure dry hydrogen; it 
was allowed nearly to cool in this gas, and dry air was then passed over for some time, 
the boat being afterwards rapidly transferred to a well-stoppered tube for weighing. 
The dried charcoal was burned in a very slow current of pure dry oxygen, the resulting 
products being allowed to pass over the red-hot cupric oxide, and finally over a layer of 
about 8 inches of lead chromate, heated to incipient redness. The efficiency of this layer 
in retaining all sulphurous acid was fully established by preliminary test experiments. 
The following tabular statement (Table II.) gives the percentage composition of 
the five samples'* of gunpowder employed in these investigations as deduced from the 
analytical results. 
In every instance at least two determinations were made of each constituent, the 
means of closely concordant results being given in the Table. 
This Table also includes the results of analysis by Bunsen and Schischkoff, Karolyi, 
Linck, and Federow, of the gunpowders employed in their experiments. 
* The authors are indebted to Colonel C. W. Youxghusbajo), R.A., F.R.S., the Superintendent of the 
W altham- Abbey Gunpowder Works, for having selected and furnished to them the samples of English gun- 
powder employed in their investigations. 
