STATER OP PHILIP OF MACEDOtf. $$ 



ness of gold and of silver was judged by the colour it took in very imper- 

 the fire, and that of its streak on the touchstone. * ect * 



These methods, though practised by experienced men> 

 can give only very inaccurate results, and which may be va- 

 ried by a number of circumstances ; as strong cleaning by 

 aqua fortis, a complication in the alloy, a difference in the 

 alloy, &c. 



Archimedes would not have applied the laws of specific 

 gravity to ascertain the falsification of the crown of Hiero, 

 if he could have done it by a better method, and particu* 

 larly by a method known and commonly practised. 



It is well known too, that, under the triumvirate of Mark 

 Antony, every street in Rome erected a statue to Marius 

 Gratianus, who had invented and introduced one of these 

 approximative methods, that have been mentioned ; and 

 this denotes the infancy of a useful art, the first steps of 

 which are highly encouraged, because they are considered 

 as conducive to the public welfare. 



(4) By employing alkaline sulphurets the solution of gold Sulphurets. 

 may be effected : metallic sulphurets only must be under- 

 stood here. 



(5) Mr. de Robilant, in his account of the processes em- Italian mints, 

 ployed in the mint of Turin, says, that cementation is the 



process of refining commonly employed at Venice, Genoa, 

 and Florence, where zechins are coined of nearly pure 

 gold. 



(6) As Mr. Fabroni says, it is not easy to explain the Process of 

 grounds of the process described by Agatharchides, or of ga 

 that which appears to be still practised at Lyons. These 

 processes should be repeated, attending to their progress 



with care, and applying to them the means of modern che* 

 mieal analysis, particularly the pneumatochemical appara- 

 tus. The nature of the gas that traverses the fluid silver 

 should be ascertained, why it forms under such a pressure, 

 why it does not flow back through the pores of the cru- 

 cible, &c. 



The^ex peri men t related by Mr. Fabroni does not appear 

 to me sufficiently conclusive, to decide the question. 



(7) Reaumur says, Memoires de PAc. des Sciences, An. Fineness of 



hi*, P . 87,'tiot fijir** 



Ds Th« 



