®^ CHEMISTRY. 



MERCURY OR QUICKSILVER. 



Occurs in the metallic state ; but more frequently as a sulphide or 

 chloride;— extracted by heat, which sublimes the mercury 



rrop —The only metal fluid at ordinary temperatures ;— has a 

 silver-white colour, and brilliant lustre; becomes solid at —39° when 

 It IS ma leable ; boils at 662o ;_sp. gr. 1 3-6 ; that of frozen me'rcury, 

 about 14. Pure mercury is not altered by the air at common tern- 

 peratures, but absorbs oxygen when heated. Hydrochloric acid has 

 no action, nor sulphuric acid, unless concentrated and boiling ; nitric 

 acid even when cold and dilute, acts upon it, forming a niliate 



Mercury forms two oxides, the black and the red. The eq. is*202 

 ^TT'^'-^'"'''^ ^' ^^^' (^^^ham, Kane, &c.) The nomenclature 

 ot the different compounds will, of course, depend upon the adop- 

 tion of either one of these. ^ 



Protoxide, HgO, (suboxide, Hgp.)-Prepared by action of caustic 

 potash on a solution of the nitrate, or on calomel ; it is a dull erav 

 powder, insoluble in water ;— decomposed, by the action of light, into 

 the red oxide and metallic mercury. 



Feroxide, HgO„ (protoxide, HgO,) red oxide. ^Prepared by the 

 combined agency of heat and mr ; by heating the nitrate ; or by pre- 

 cipitation from a solution of corrosive sublimate, by means of potassa 

 It IS often called red precipitate. It is in the form of fine red shinino- 

 scales, very slightly soluble in water; converted by heat into me"! 

 tallic mercury and oxygen. 



Chlorine forms two compounds, cabmel and corrosive sublimate 



^ Frotochloride, or calomel, HgCI, (subchloride, Hg^Cl.) Prepared 



either hy 2^recipitation, by means of chloride of sodium in a solution 



of the nitrate ; or by subliming together the protosulphate of mer- 



cury and chloride of sodium. The rationale is as follows :— 



Protosulphate of ^ Mercury -^i:^ Calomel, HgCl, 



Chloride of so- V Chlorine 



dium ) Sodium ^^.Sulphate of soda. 



As prepared by ordinary sublimation, calomel occurs in yellowish 

 white masses; but if the vapour be conducted into a recipient con- 

 taming watery vapour, it is condensed in a very fine white powder. 

 It IS insoluble, tasteless ; sp. gr. 7-2 ; is apt to contain a little corro- 

 sive sublimate, which can be removed by washing, or throwing 

 down by ammonia. Potassa or lime decompose it, throwing down 

 the black oxide. ° 



Bichloride or corrosive sublimate, HgCl,, (called chloride, HgCl.) 

 —Prepared by burning mercury in chlorine gas; by action of hy- 

 drochloric acid on the red oxide; or preferably, by subliming to- 

 gether the bisulphate with common salts, thus :— & 



