1882.] 



Chemical Theory of Gunpowder, 



361 



February 23, 1882. 



THE PRESIDENT in the Chair. 



The Presents received were laid on the table, and thanks ordered for 

 them. 



The Bakeeian Lecture on the " Chemical Theory of Gun- 

 powder," was delivered by Professor H. Debus, Ph.D., F.R.S. 

 Received February 8, 1882. 



The following is an Abstract : — 



1. Dr. Jebb* mentions a manuscript as existing at Oxford, entitled 

 "Liber ignium ad comburendos hostes," by Marcus Graacus, probably 

 written in the eighth century, wherein the preparation of gunpowder 

 is accurately described, and Bellani reports that the English used 

 cannon at the Battle of Crecy. Gunpowder, therefore, has been 

 known more than a thousand years, and its use for the purposes of 

 war more than five hundred, nevertheless, no chemical theory of the 

 combustion of gunpowder has hitherto been proposed which will 

 enable us to calculate the quantity of each of the chief products of 

 combustion from the known composition of a given weight of powder, 

 or the amount of heat generated during its metamorphosis. A theory 

 which can solve these problems I have the honour to submit in the 

 present paper to the Royal Society. 



2. The constituents of gunpowder — saltpetre, charcoal, and sulphur 

 — are transformed during combustion into the following products : — 

 Potassic carbonate, potassic sulphate, potassic disulphide, potassic 

 sulphocyanate, carbonic acid, carbonic oxide, nitrogen, sulphuretted 

 hydrogen, marsh-gas, ammonia, hydrogen, and water. 



The hydrogen compounds — sulphuretted hydrogen, ammonia, and 

 marsh-gas, the free hydrogen and potassic sulphocyanate — do not, as 

 a rule, amount together to more than about two per cent, of the 

 weight of the powder from which they have been produced ; and as 

 their formation is not the direct result of the reactions which cause 

 the explosion of the powder, they are regarded as secondary products 

 and not considered in a discussion of the chemical metamorphosis of 

 gunpowder. 



Besides the potassium salts mentioned, potassic hyposulphite has 

 been found as one of the constituents of the solid residue left by 

 powder after its explosion. According to experiments by the author, 

 which have been confirmed by Noble and Abel, this salt is formed in 

 considerable quantities from potassic sulphide during the analysis of 

 * PoggendorfEj " Greschichte der Physik," 87. 



