140 



MERCURY 



MEREDITH 



a bright sciii-lct iodide of mercury. (2) The galvanic 



liich nmv If applied in various v. 

 which tlie simplest is tin- ' gui.iea ami key test,' 

 devised l>y Wollanton. He placed a drop of the 

 lluid -ii-pc.-ted to contain COIIOMM- sublimate on a 

 guinea, and simultaneously touched it ami the sur- 

 tin- guinea with an iron key : metallic mer- 

 cury was deposited on the gold in a bright silvery 

 Main. (3) Precipitation on ro|>|icr, and reduction. 

 To apply this test we acidulate tin- suspected lluiil 

 with a few ili op- ui hydrochloric acid, and intro- 

 duce a littli- line copper gauze, which soon liecomes 

 coated with mercury. Uu heating the guii/e in a 

 reduction lulu" the mercury is obtained in well- 

 delincd globule-. 



With iodine and bromine mercury forms two 

 iodides and bromides. corres|M>nding in coinpo-iiion 

 to tin- rhloride-. Ilnth the iodide* are used in 

 medicine; the bromide* are of no practical import - 

 am-e. The tubioilule, Hg a l, \* a green powder 

 formed liy triturating S pails of iiKline with S 

 of niereiny, ami is of far lesi interest than the 

 iwliile, Hgl, which i- most simply obtained by pre- 

 cipitating a solution of corrosive -ublimiite by a 

 (Miliition of iodide of potassium. The precipitate 

 is at first salmon coloured, but soon changes into a 

 brilliant scarlet crystalline deposit. 



Sulphur forms two compounds with mercury 

 viz. a subsiilpliide, llg_.S. a Mack powder of little 

 iiiipnitiiiiee, and a sulphide, HgS, which occur- 

 naturally its Cinnaliar (Q.V.). Stnjihtde of wr<-nri/ 

 is thrown down as a black precipitate bypassing 

 sulphuretted hydrogen through a solution of a pcr- 

 wilt of mercury (corrosive sublimate, for example). 

 \Vhcn dried and sublimed in vessels from which 

 the air is excluded, it a nines its ordinary red 

 colour. The well-known pigment i-mnHiim is sul- 

 phide of mercury, and i- sometimes obtained from 

 pure cinnabar, but is more frequently an artificial 

 prod net. 



.ry unite- with mint metals to form Amal- 

 gams (<).v.), several of which are employed in the 

 int-. Of the numerous organic compounds of 

 mercury it is unnecessary to mention more than 

 the Fulminates () v. ) and the cyanide, HgCy, 

 which may IK- prepared by dissolving the red 

 oxide of mercury in hydrocyanic acid, and is the 

 bent source from which i<> obtain cyanogen. 



The ii-cs of mercury are so numerous that a very 

 brief allusion to the most important of these must 

 sullicc. It i- employed extensively in the extrac- 

 tion of gold and silver from their ores by the -process 

 of amalgamation. Its amalgams have IK-CII largely 

 employed in the processes of silvering ami gilding, 

 Bin! -i. me (a- those of copper and cadmium) are 

 employed by the denti-t for stopping teeth. It is 



indi-pcnsablc in tl instruction of philosophical 



in-tuimeiits, and in the laboratory in the form of 



the mercurial bath, Arc. It is th'e source of the 



valuable pigment vermilion. The use of its 



chloride in anatomical preparations has been 



nlrc.-i.lv noticed; it in similarly found that wood, 



cordage, and canvas, if stKiknl in a solution of this 



salt i I p.ut to iKi ,,i so ,,f atcrl. arc IM-UIT able to 



when e\|iHl t> the combined destine- 



uillncnrp of air and moisture-. 



Mi UK is u i moi \h in ricvANiiMKncrniALs. 



lie niiTi-ury i- u-eil in medicine ill a st.'ite of 

 very line divi-ion in || M . f nr m of gniy jMiwdcr. blue 



Fill, ineri-niial ointment, and other preparations. 

 I is also used as merciirous and mercuric oxides 

 and ult. As with other metals, the incrciiiial 

 lion* have a local action and an action 

 ntt.-r alisorption into the lilo.nl. 'J'he Intensity of 

 the local action varies, however, with the null 

 vidnal pn-pnration ; the pprsalt* U-ing solulile in 

 water, and hence cajMible of priTJiiitating albumen 

 at once, are very irritating, while the mcrcurous 



salts and imcomhiucd mercury, Vicing insoluble in 

 water, exert an effect on!y in so far n> tin \ an- di- 

 solved in the secretions. These differences in local 

 action have a very great influence in determining 

 their application- in medicine. 



Locally, the various ointments, liniments, and 

 plasters are used as stimulants, astringent-, anti- 

 M-ptii's, and parasiticides, the persalt.* are used as 

 antiseptic lotions, while the protosi-.lts are little 

 employed locally, except Calomel (<|.v.) in powder. 



Absorption of mercurial preparations from the 

 intestinal canal or skin takes place very readily, 

 and in an hour or less the mercury may be detected 

 in most of the secretions. Alter absorption into 

 the blood all the preparations ha\e the same action. 

 In minute doses they act us alteratives, improving 

 nutrition. In larger doses, such as are ordinarily 

 used, tuey also < xert profound alterative efli 

 but care must 1* exercised in their administration, 

 other\vi-e symptoms of chronic poisoning are upt 

 to ensue. These consist in exec ive salivation, 

 inflammation of the mouth nnd gums, ami dys- 

 pepsia, while in severer case- caries of bone, 

 nervous symptoms, a watery condition of the 

 blood, albiiminuria, cachexia, and other serious 

 complications may occur. The mercurial prepara- 

 tions are given internally in svphilis, in serous 

 inflammations, and in dropsy as diuretics. Certain 

 of them, such a gray powder, blue pill, aim 

 calomel, are used as purgatives and as intestinal 

 antiseptics. 



The doses of the different preparations vary- 

 greatly, those of the pel-salts l>cii:g very much 

 smaller than in the ca.se of the other preparations. 

 Some persons are peculiarly susceptible to the 

 action of mercurials, and show symptoms of ehror.ic 

 poisoning after very small amounts. 



With regard to acute mercmial poisoning, this is 

 due to irritation of the intestinal canal, and is only 

 seen with the soluble salts when taken in over- 

 doses. The perchloride (corrosive sublimate) has 

 IM-CII most frec|iicntly employed for the purpose of 

 poisoning. The .symptoms come on immediately, 

 with a burning pain in the throat and violent pain 

 in the abdomen, with severe vomiting and purging. 

 There is al\\a\s a good deal of collap-c. Albuircn, 

 in the form of white of egg, is the licst antidote. 



MeroiirV* I><x;'s (.Vi-ircm/>), a genus of 

 plants of tfie natural jmler Euphorbiacea-. The 

 Common Hog's Mercury ( .'/. JH n inii'x) is very com- 

 mon iii woods and shady places in Britain. It 

 has a perfectly simple Mem, about a foot high, 

 with rough ovate leaves, and axillary loose spikes 

 of greenish Mowers. It turns a glaucous black 

 colour in drying, and the root contains two colour- 

 ing substances, on,- blue and the other carmine. 



It i- very poisonous. The mercury which soi >ld 



writers mention ILS a potherb is not this plant, 

 but Kngli-b Mercury, or Wild Spinach (<Jlirnn- 

 podium limuix Hi iirn-iix I. Annual Uog's Mercury 

 (.I/. IIHHIIII) is a much rarer British plant, and 

 1--- poisonous. The leaves are indeed eaten in 

 C.ermany as spinach. A half-shrubby species i . I/. 

 t<n ,: iitunn ), found in the countries near the Medi- 

 terranean, has enjoyed an extraordinary reputation 

 i mm ancient times; the ab-urd belief mentioned 

 by 1'liny lieing still retained, that if a woman utter 

 conception drink the juice of the male plant she 

 will give birth to a IMIV, and if of tin.- female plant 

 her offspring will be a girl. 



!Hr->. si-i I.KS OF. See SISTERHOODS. 



Sler <lc tilnce. See ALPS, GLACIERS. 



Meredith. (iKniKJK. novelist and |x>ct. -.vis liorn 

 in Ilamp-bire, 12th February 1S2H, and made his 

 ln-t appearance as a ]H-( with ' Chillianwallah' 

 in I'/Hittilii-rx'x .{', iiriin/ for July 1S49. This was fol- 

 lowed in 1851 by a little volume of Poems, and in 



