On Argental Mercury. 43 



teen before obferved, is the mod complex of all tbofe exhir 

 bited by mineral fubftances. It is produced by the interfec- 

 tion of' the faces which belong to the following fix kinds of 

 regular or fymmetric folids, viz. the cube, , the o<3aeuron, 

 the rhomboidal dodecaedron, the folid with.. 24 trapezoidal 

 facets, the folid with 24 ifolceles triangular facets, and the 

 folid with 48 fcalene triangular facets. Tiie complete cryflal 

 is terminated by 122 faces. The exprelhon of this fpnu,. 



jeprefentcd fig. 2, is P B B A E E. 



The incidence of the faces of the primitive fo^m with 

 tbofe of the oftaedron is 125' i^5'52"; with thofe of tiie folid 

 having 24 trianoular facets is 153' 28' 4" j with tbofe of the 

 folid having 48Yace5 i'6° 53' 36". ' 



Hitherto no complete anatomy of argental mercury has 

 been publiflied ; mineralogitis were fatisfied with acquiring 

 an ajiproximate kno'vledge of its compofition from liinple 

 experiments: it was thereft)re of importance to determine 

 with accuracy the elementary principles of this mineral, and 

 to fix the proportions. This analyfis was attended with no 

 kind of difficulty *. 



Sixtv parts of this mineral were expofed in a crucible to 

 the action of a low heat, which was fucceffivdy increafed, 

 and continued as long as was neceflary to volatilize. all the 

 mercury. The cryrtal's, without fuffering any fcnfible lofs 

 of volume, were changed into fpongy malTes, which to- 

 wards the end of the oj-ieration funk down and united into a 

 metallic button : the weight of this button was found to be 

 16-5 parts, from which it was concluded that the weight of 

 the mercury volatilized was 43 ■5- 



This button was pevfcilly malleable, and had all the ap- 

 pearances of tlie pureft filver. To afcertain its purity it was 

 expofed to the a6lion of nitric acid proved by nitrate of filver. 

 The folution was elfecled without any refidiium. 



Oxygenated muriatic acid was poured into the folution, 

 and the precipitate of muriate of filver was colleded on the 

 filter. The liquor tried by carbonate of potafli furniflied no 

 precipitate ; the filver then contained no foreign metallic 

 fubftance. 



In regard to the ftate of the mercury in its combination. 

 It is cei-luinly not neceffary to prove that it cxifis in a folid 

 (late. To be convinced of it, nothing will be neceffary but 



* The cryfttils fnbjciled to anslyfis were covcrcl v.itlia ftraium of 

 liipjid inert ury, which was rerooyed by prdhng them bciwecn tlic finger* 

 In lyft \va.x, 



10 



