ART OF MAKING GUN-FLINTS' 93 



xvafhed, dried and ignited, weighed 97 grains. Ammonia 

 was afterwards added to the clear liquid, where it produced 

 a flight yellowifh white precipitate, which after being well 

 Wafhed and dried weighed one grain, and was found to be a 

 mixture of alumine and oxide of iron. The fluid feparated 

 from this fmall portion of iron and alumine, gave no other pre- 

 cipitate on the addition of carbonate of potafti, and the waters 

 ,ufed in the wafhing left no refidue when they were evaporated 

 to drynefs. . The refult therefore was filex = 97 grains, alu- 

 mine and oxide of iron == 1, lofs = 2. The author confiders 

 it to be a very remarkable fact, that the iilex pyromachus 

 ilioifld contain only iilex and water, the alumine and iron be- 

 ing too fmall in quantity to be confidered as eflential to its 

 compofition, or to influence its habitudes. Quartz alfo, from Difference be- 

 the analyfes which have been made, appears to contain only tween f,Jex an * 

 filex ; yet the more he examines the two fubftances, the more quar z * 

 lie finds reafon to fuppofe them effentially different from each 

 other ; fince the one refufes to aflume the cryflalline form, 

 and the other aflumes it and becomes clear, even in contact 

 with the flint itfelf. The one appears to be incapable of ad- 

 mitting water into its compofition, while the other conftantly 

 contains it until it begins to be decompofed. He offers a 

 query, whether the difference may not confift in the fmall 

 portion of combuflible or fatty matter, which caufed the de- 

 tonation with nitre, or whether the quartz may not, like alum, 

 acquire its property of cryflallizing from the addition of fome 

 other fubffance. This queftion, as he remarks, muft "be re- 

 folved by future experimental enquiries. 



The analyfis of the whitifli fpots afforded filex 98 grains, 

 oxide of iron 1, carbonate of lime 2. That of the abfolutely 

 opaque parts gave five parts more of carbonate of lime ; and 

 laflly, the analyfis of the white coating naturally enveloping 

 themaffes, afforded 86 parts of filex, 1 oxide of iron, 10 car- 

 bonate of lime, and '3 lofs. Thofe analyfes which afforded 

 no alumine, fhew that this earth is not effential to the filex, 

 .and the abfence of lime in the firft analyfis fhews that it was 

 an accidental ingredient in the latter. 



Mineralogical fituation. Jn France in the environs of St. Minerslogical 

 Aignan, fituated in the department of Loir-Cher, and in Nation, 

 that of L'Indre, and the departments which occupy the valiies 

 of Siene and Marne, are principally the places where this 



(tone 



