F. A. P. Barnard on the Explosive Force of Gunpowder, 243 
In the Encyclopedia Britannica, last edition, article Gun-pow- 
der, Mr. Tomlinson, assuming that the gaseous products of the 
combustion of gunpowder are carbonic oxyd, sulphurous acid 
and nitrogen exclusively, computes a theoretic enlargement of 
volume as 1: 787:3. Assuming further that the elevation of 
temperature is such as to treple this volume, he make the maxi- 
mum pressure 2360 atmospheres. 
he interesting Reports of Capt. Rodman, upon metals for 
heavy guns, and upon the qualities of cannon-powder, published 
in 1861 by authority of the Secretary of War of the United 
States, contain statements of experiments in which powder was 
ode the for the purpose, contrived ot. Rodman himsel 
and described in the volume, was 185,000 Ibs. per sq. in.—equiv- 
ent to more than 12 atmospheres. For certain reasons 
aximum 
pressure cannot exceed 743 atmospheres, or about eleven thou- 
sand pounds to the square inch. i é 
These examples are cited not with any intention to exhaust 
the list of authorities, but simply for the purpose of illustrating 
the wide differences between them. None of the results pre- 
Sented can be said to rest upon entirely unexceptionable data; 
and among those which most largely differ, are some which seem 
possess almost equal claims to acceptance. In the year 1857, 
however, there was published in Poggendorf’s Annalen for No- 
vember, a paper by Messrs. Bunsen and Schischkoff, of Heidel- 
berg, entitled “Chemische Theorie des Schiesspulver,” in which 
-this subject is investigated with a thoroughness never before 
attempted, and the data are presented for determining the maxi- 
mum force of gunpowder in a form which seems to leave nothing 
to desire.’ This force is computed by them to 
- ? This Journal, [2], xxxvi, 106. 
