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sion of the mouldy owing to the great heat necessary to give the 

 metal the required looseness and pliancy. The liquid metal 

 has a considerable amount of cohesion, which tends to make it 

 form into pretty large drops, like that observed in quicksilver ; 

 which drops cannot be separated into smaller, or reduced with- 

 out great force. Consequently there may be openings or hollows 

 in the mould into which the melted metal will not easily enter ; 

 and if these be very minute, it will be inadmissible. Besides, 

 the substance which forms the mould must not only be capable 

 of enduring a very high temperature, but sufficiently porous 

 to allow the air to escape. 



The native metals which are found in mineral deposits are 

 often enclosed in quartz ; but on whatever substances they may 

 be, they present the exact impression, even the most minute 

 cracks of the mould. Nor are the substances on which such 

 metals are found always confined to those that resist intense 

 heat ; on the contrary, native copper and silver have been found 

 deposited on timber, and decayed leaves in old mines. It is 

 therefore very evident that the ordinary process by fusion is not 

 capable of fulfilling the above conditions of the metals in the 

 mines : but it is identical with those formed in the humid way 

 by electro-magnetic action. 



In speaking of metals, we should not forget that a great num- 

 ber of them are found not as solids, but in solution in the rocks. 

 Indeed there is no rock in situ but is found more or less saturated 

 with mineral waters. 



Iron is abundant almost in all mineral waters. 



Copper is found in solution in all the copper mines in Europe 

 and America, and a large proportion of copper is obtained by 

 the introduction of iron to precipitate the metal from its sol- 

 vent. 



Other metals are capable of being in solution as well as in 

 their solid state. 



Platinum remains in solution with one part of nitric to two 

 of muriatic acid. 



Gold is soluble in nitro-muriatic acid. 



Silver is soluble in nitric acid. 



Nickel dissolves in nitric acid. 



Zinc, Lead, and in a word, all metals, are susceptible of remain- 



