174 COMPOSITION AND ANALYSIS OF GUNPOWDER. 



There is nothing, indeed, said of vinegar in the description of the 

 ptian mines before mentioned : but Pliny expressly affirm?, 

 that it was the quality of vinegar, when poured upon rock?, to split 

 such as an antecedent fire had not split ; and that it was the custom 

 of miners to burst the rocks they met with, by fire and vinegar*. 

 This account of Hannibal's using vinegar in splitting the rocks, is 

 generally looked upon as fabulous: for my part, I can easily con. 

 ceiye, that a few barrels of vinegar might have been ofgn-at use, if 

 the ro; ks were of the limestone kind 5 aud, whether they were so or 

 not, I leave to be settled by those, who have visited the place where 

 this famous attempt was made. Vinegar corrodes all sorts of lime- 

 stone and marble rocks ; and hence, being introduced into the 

 crack made by the fire, it might be very efficacious in widening 

 them, and rendering the separation of large lumps by iron crows 

 and wedges more easy. It is erroneously supposed, that a large 

 quantity of viuegar was requisite, for the vinegar did not reduce 

 the whole mass of rocks into a pulp ; since Livy clearly informs us, 

 that after the action of both the fire and vinegar, they were obliged 

 to open their passage by iron instruments, which would have been 

 wholly unnecessary, had the main body of the rocks been dissolved 

 by the vinegar i. 



SECTION II. 

 Composition and Analysis of Gunpowder. 



GUNPOWDER is an artificial composition, consisting of saltpetre, 

 sulphur, and charcoal. The principal things to be respected in the 

 making of gunpowder are, the goodness of the ingredients ; the 

 manner of mixing them ; the proportion in which they are to Le 

 combined ; and the drying of the powder after it is made. 



Saltpetre, in its crude state, whether it be brought from the East 

 Indies, or made in Europe, is generally, if not universally, mixed 

 with a greater or less portion of common salt : now a small por- 

 tion of common salt injures the goodness of a large quantity of 

 gunpowder; hence it becomes nece-sary, in making gunpowder, 

 to use the very finest saltpetre. The purest sulphur is that which 



* Sata rutnpit infusum (acetum) qcte non ruperit ignis antec<-dcns. PJin. 

 Nat. Hist. L- 23. s. 27. & L. 33. s,21. where by Silicea cannot be understood 

 what we call flint-, since vinegar ha no action on flints. 



t ardentiaqor saxa infuso nrrto putrrfaciunt. Ita torridam incrndto 

 rupem frrro pandunt. Liv. Hist. I. xxi. c. xzxvii. 



