100 Preparations of Gold htely employed medicinalhj , 



of gold and soda. These he considers as superior to mer- 

 curials. Some experiments by Mr. Vaiiqiitlin, on the 

 preparations (»f gold thus introduced into notice, have al- 

 ready been given : but we shall now present our readers 

 with some remarks on the subject by the gentlemen above 

 mentioned, one of vi'hom enjoyed the advantage of a per- 

 sonal acquaintance wiih Dr. Clirestien at Montpellier. 



The first preparation of gold employed by this physician 

 was the metal in a state oF rninuie division. To obtain 

 this, he found an amalgam, by triturating leaf-gold with 

 seven times its weight of mercury in a marble mortar with 

 a glass pestle, and then expelling the mercury by means of 

 a powerful lens in the height of summer, or dissolving il 

 out by pure nitric acid. 



The present writers recommend rather to precipitate a 

 solution of muriate of gold by a solution of sulphate of 

 iron at a minimum, filtering, and washing the precipitate 

 with water, acidulated by muriatic acid, in order to dis- 

 solve out the oxide of iron mingled with the precipitated 

 gold. When the gold is thoroughly dried, it is in the 

 form of a deep brown powder, though in the metallic 

 state; all metals losing their brilliancy by being minutely 

 divided. 



To prepare the oxide of gold precipitated by potash, they 

 direct one part of nitric acid at 40^ [sp. gr. 1'396] to be 

 mixed with four of muriatic acid at 12" [l*089] ; and cu- 

 pelled gold to be heated with eight times its weight of this 

 menstruum in a matrass with a long, narrow neck, till it 

 boils gently. When no more gold will dissolve at this 

 temperature, the solution is to be poured off, and evapo- 

 rated to dryness in another matrass bv a gentle fire. The 

 residuum of this evaporation is to be dissolved in distilled 

 water, and filtered. 



The filtered solution is to be treated with potash, to se- 

 parate from it the oxide of gold ; but in this there are great 

 difficulties, and the whole cannot be thrown down, with- 

 out part of it being reduced to the metallic state. The 

 cause of this is not known ; but the authors ascribe it, 

 I. To the formation of a soluble triple muriate, which takes 

 place when the potash is poured into the solution of mu- 

 riate of gold : 2. To the excess of acid alwavs present in 

 this muriate : 3. To the more or less caustic state of the 

 alkali emjiloyed : 4. To the greater or less quantity of this 

 substance added to the muriate of gold. 



When a solution of caustic potash is poured into a sa- 

 turated 



I 



