CO ANNUAL OF SCIENTIFIC DISCOVERY. 



was found to have been consolidated into cylinders of one and a quarter 

 inches in diameter, with smooth, polished surfaces, every trace of its granu- 

 lar character having disappeared. 



From the Report of Mr. Abel, the chemist of the War Department, we 

 learn that the specific gravity of the specimens was increased by the pres- 

 sure, but not to so great an extent as might have been expected. 



The specimens, having been granulated, were then burned, and it was 

 found, on comparing the results with those of similar experiments on ordi- 

 nary press-cake, that the amount of residue left by the compressed powders, 

 after ignition, was greater in proportion as the pressure was increased. 

 This increase of residue is probably to be attributed to the more gradual 

 combustion and the diminished intensity of heat generated by compressed 

 powder. 



Experiments were then instituted to determine the amount of charcoal 

 left unconsumed in the residue. They showed conclusively that the con- 

 densation of the powder had caused a more perfect chemical action in com- 

 bustion, as the per-centage of carbon was considerably diminished in the 

 compressed powders. Nitric acid was very carefully searched for in the 

 residues of the compressed powders, but none could be detected, although 

 in ordinary gunpowder a portion of the acid of the saltpetre always escapes 

 decomposition. 



An important objection to the application of increased pressure in the 

 manufacture of gunpowder, notwithstanding the more intimate mechanical 

 mixture of its constituents, is, that the quantity of the residue left after com- 

 bustion is increased, and a larger proportion of powder escapes ignition 

 altogether when a charge is fired from a gun. If, however, larger quantities 

 were submitted to compression, it is probable that the closer contact of the 

 particles might be found to act beneficially, and a powder be produced of 

 an improved and stronger quality, resulting from a judicious application of 

 increased pressure and a more perfect system of granulation. Mechanics' 

 ( London ) Magazine. 



Mr. Lynall Thomas, in a communication to the Royal Society, says: 

 Since the year 1797, when Count Rumford made his experiments for ascer- 

 taining the initial force of fired gunpowder, an account of which appears in 

 the Philosophical Transactions of that year, very little light has been thrown 

 on the subject. Count Rumford's experiments, valuable in many respects, 

 afforded, indeed, nothing conclusive respecting it. The object of the present 

 paper is to show the unsatisfactory natui'e of the present theory of the action 

 of gunpowder, and to point out some of the principal errors upon which this 

 theory is based. For this purpose, the results of various experiments made 

 by the author, and which were repeated in the presence of a select com- 

 mittee at Woolwich, are described and explained. These experiments are 

 held by the author not only to afford complete evidence of the unsoundness 

 of the present theory, but as sufficiently conclusive to serve as the basis for 

 the formation of a new set of formula?, both correct and simple, in place of 

 those at present in use. The initial action of the fired charge of powder 

 upon the shot, the first movement of the shot itself in the gun, and the 

 force exerted upon the gun by different charges of powdei', and, therefore, 

 the actual strength of metal required by the gun, arc circumstances which, 

 as the author believes, have not only been misunderstood, but for which 

 laws have been assigned directly opposed to the truth. As an instance of 

 tLis, the hitherto received theory supposes that when a shot is forced from a 



