52 



IfFt€t of heat. 

 Oxidation. 



Diftillation. 



The flint is an 

 imperftdl hy- 

 drophanes. 



. 



Chemical analy- 

 sis ; fufion with 

 potafh j precipi- 

 tation of the 

 filex, &c. 



ART Of MAKING ;GUN-FUNTS. 



humidity which is ofien very perceptible when it is recent, 

 it can then no Jonger be broken into gun-flints, as its fracture 

 is lefs eafy. The workmen carefully reject, all Ihofe 'which 

 have loft this favorable degree of moifture. Perhaps they 

 might be reflored by keeping them in a damp place, or co- 

 vering them with earth, and by thefe means at leaft they 

 might fucceed in prefer ving'thofe intended to be worked up 

 in winter. r ' ' 



When the fragments are thrown upon a red hot plate of 

 iron it flies and cracks, and becomes opaque. When pro- 

 jected in powder upon nitre in fufion, it gives a few iparks 

 with flight inflammation and detonation. 



When calcined in a tell it lofes one 250th part of its weight, 

 increafes in bulk, becomes extremely white, and fo brittle as 

 to be almoft friable. In this ftate it refembles the fineft porce- 

 lain bifcuit. 



When diftilled in a retort by ftrpng heat it affords a little 

 carbonic acid gas, and a quantity of water amounting to 200. 

 parts of the weight before indicated as its fpecific gravity ; 

 but gives no fign of the combuflible matter which in the pre- 

 ceding experiment caufed the nitre to detonate. 



This water, which appears elfential to all. the flints, and 

 may be called their radical water, is the caufe of their trans- 

 parency. Expofure to air by drying them renders them 

 opaque ; fo that they may be confidered as imperfect, hydro- 

 phanes; for they do not again abforb, but with difficulty the 

 water neceifary to their tranfparence. This water alfo con- 

 tributes to the connection of their integrant particles, whence 

 their fracture becomes more equal, and is harfli when they 

 have loft it. Thefe flints when recently dug up even afford 

 an aqueous vapour when ft ruck, and the face of the fracture 

 is humid, and as it were moift. 

 Chemical analylis. 



Citizen Vauquelin examined 100 parts of filex pyromachus 

 of abrownifh colour, and uniformly femi-tranfparent from the 

 hills of La Roche Guion. He mixed the mafs with 400 grains 

 of very pure potafh, which by fufion in a filver crucible af- 

 forded a compound, which after cooling was diffufed in water, 

 and then fuper-fatu rated with muriatic acid. The very clear 

 folution was evaporated to drynefs, re-diflblved in water, and 

 the filex thus Saturated, and left upon the filter after being well 



waflied, 



