ESSAY X. 



METHOD OF PREPARING MERCURIUS DULCIS VIA 

 HUMIDi. 1778. 



SECTION I. 



TAKE half a pound of quicksilver, 'and as much pure common 

 aquafortis, pour it into a small cucurbit, with a pretty long 

 neck, stop the mouth with a little paper, and put it into 

 warm sand. Some hours afterwards, when the acid appears 

 no longer to act upon the quicksilver, the fire is to be so 

 much augmented as nearly to make the solution boil. This 

 heat is to be continued for three or four hours, and the 

 vessel now and then to be shaken. 1 Towards the end, 

 regulate the heat so that the solution shall gently boil for a 

 quarter of an hour. 2 In the meantime, dissolve 4i oz. of 



1 One would imagine that, when the acid no longer effervesces with 

 the quicksilver, it should be saturated ; but this is far from being the 

 case. If the heat is increased, this solution is still able to dissolve a 

 great quantity ; with this difference, however, that whereas the quick- 

 silver in the beginning is calcined, a great deal of quicksilver, in a 

 metallic form, is afterwards dissolved as appears clearly from this, that 

 not only no more elastic vapours ascend, but also that with fixed and 

 volatile caustic alkalies a black precipitate is obtained, otherwise, when 

 the solution contains only calcined quicksilver, the precipitate is yellow. 

 If the black precipitate be gently distilled, quicksilver arises, and there 

 remains a yellow powder, which is precisely that part of quicksilver 

 which, in the beginning of the operation, was calcined by the acid of 

 nitre. 



2 The fire must necessarily be augmented, in order to keep the 

 nitrated mercury dissolved, which is very much inclined to crystallise, 

 even in the heat. There commonly remains some undissolved quick - 



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