NITRE. 467 



pound, enables the nitrous acid to oxygenize the sulphurous and form 

 sulphuric, while the nitric oxide is again evolved, to perform the same 

 function anew.* At Fahlun, in Sweden, they are enabled to manu- 

 facture sulphuric acid in small leaden chambers, by placing upon the 

 floor flat glass vessels containing nitric acid, which is decomposed by 

 the sulphurous acid gas, thus evolving nitric oxide gas and answering 

 the purpose of nitre, which is here omitted. This mode is less eco- 

 nomical than the common one, but it produces a purer acid, contain- 

 ing only . 1 or .2 of foreign matter, consisting entirely of sulphate of 

 lead, while the common acid contains .5 or .6 of foreign bodies.f 



4. GUNPOWDER, &tc. 



(a.) History. First known to the Chinese ; neither its European 

 discoverer nor the period of the discovery is exactly ascertained ; 

 attributed to Roger Bacon and to Swartz, a German, in 1320.J 



(b.) Composition. Gunpowder is an intimate mixture of nitre, 

 sulphur and charcoal; the proportions vary in different manufacto- 

 ries, and for different purposes ; but those employed in the Royal 

 Mills of England, are 75 nitre, 15 charcoal, 10 sulphur.^ These 

 are the proportions generally employed in other countries. The 

 nitre, being the most expensive article, is sometimes stinted ; this of 

 course injures the quality of the powder. Common gunpowder often 

 contains not more than .50 of nitre. || 



(c.) Process in the Royal Mills of England. The ingredients 

 are as pure as possible. The nitre is carefully purified. Common 

 salt, uncombined potassa and sulphate of magnesia,1F are the most 

 common impurities, and cause the powder to deliquesce. The 

 charcoal is made in ignited iron cylinders, and the sulphur must be 

 free from acid. The ingredients are separately pulverized ; then 



* Ann. de Chim. Vol. LIX, and Davy's Elements, Am. ed. p. 1. 



t Berzelius, Ann. de Chim. et de Phys. Tome IX, p. 162. The acid made near 

 New York, contains only .1 or .2 of foreign matter. J. T. 



$ Gunpowder was not known in Europe before the end of the thirteenth century, 

 probably not before 1320 ; it was well known in the middle of the fourteenth cen- 

 tury, and cannon were used in Germany before 1372 ; first used by the English at 

 the battle of Agincourt, A. D. 1415. See Nicholson's Journal, 8vo. series. 



In France 75. nitre, Sweden 75. Poland 80. Italy 76.5 



9.5 sulphur, 16. 12. 12.5 



15.5 charcoal, 9. 8. 12.5 



100. 100. 100. 101.5 



Dr. Watson's essays. 

 At present, both in England and France, 7 JVitre. Charcoal. Sulphur. 



common powder contains $ " - 75 12 12 



Shooting powder for the sportsman, 78 12 10 



Or, 76 15 9 



Powder for blasting in mines and quarries, 65 15 20 



M. Bouchet's patent powder, 78 12 9 



The shooting powder is glazed by the mutual friction of the grains in a barrel, 

 revolving on an axis ; the proportion of nitre and charcoal is large, to insure its quick 

 action. Gray's Op. Chem. p. 495. || Black, Vol. I, p. 432. IT Id. 



