When cyanogen is prepared by heating mercuric cyanide, a residue known as para-cyanogen, (CN)x, is left; this is to be regarded as a polymer of cyanogen.
The next salt to be obtained was the mercuric salt, which was prepared in 1 799 by Edward Charles Howard, who substituted mercury for silver in Brugnatelli's process.
Von Liebig (1823), who heated a mixture of alcohol, nitric acid and mercuric nitrate; the salt is largely manufactured by processes closely resembling the last.
The use of mercuric fulminate as a detonator dates from about 1814, when the explosive cap was invented.
The now well-known fact that small doses of poisonous substances may act as stimuli to living protoplasm, and that respiratory activity and growth may be accelerated by chloroform, ether and even powerful mineral poisons, such as mercuric chloride, in minimal doses, offers some explanation of these phenomena of hypertrophy, wound fever, and other responses to the presence of irritating agents.
Carbon bisulphide combines with primary amines to form alkyl dithiocarbamates, which when heated lose sulphuretted hydrogen and leave a residue of a dialkyl thio-urea, CS 2 +2R NH 2 - R NH CSS NH 3 RCS(NHR)2+H2S; or if the aqueous solution of the dithiocarbamate be boiled with mercuric chloride or silver nitrate solution, a mustard oil (q.v.) is formed, R.NH CSS NH3R+HgC12-Hg(R NH CSS)2->2RNCS-}-HgS+H2S.
VERMILION, a scarlet pigment composed of mercuric sulphide, HgS.
It is also prepared by digesting precipitated mercuric sulphide with an alkaline sulphide fox some hours; it is said that Chinese vermilion owes its superiority to being made in this way.
The compounds of mercury attracted considerable attention, mainly on account of their medicinal properties; mercuric oxide and corrosive sublimate were known to pseudo-Geber, and the nitrate and basic sulphate to " Basil Valentine."
The term allotropy has also been applied to inorganic compounds, identical in composition, but assuming different crystallographic forms. Mercuric oxide, sulphide and iodide; arsenic trioxide; titanium dioxide and silicon dioxide may be cited as examples.
To mix the substance with an oxidizing agent - mercuric oxide, lead dioxide, and afterwards copper oxide - and absorb the carbon dioxide in potash solution.
A sublimate may be formed of: sulphur - reddish-brown drops, cooling to a yellow to brown solid, from sulphides or mixtures; iodine - violet vapour, black sublimate, from iodides, iodic acid, or mixtures; mercury and its compounds - metallic mercury forms minute globules, mercuric sulphide is black and becomes red on rubbing, mercuric chloride fuses before subliming, mercurous chloride does not fuse, mercuric iodide gives a yellow sublimate; arsenic and its compounds - metallic arsenic gives a grey mirror, arsenious oxide forms white shining crystals, arsenic sulphides give reddish-yellow sublimates which turn yellow on cooling; antimony oxide fuses and gives a yellow acicular sublimate; lead chloride forms a white sublimate after long and intense heating.
The solution is filtered and treated with an excess of sulphuretted hydrogen, either in solution or by passing in the gas; this precipitates mercury (mercuric), any lead left over from the first group, copper, bismuth, cadmium, arsenic, antimony and tin as sulphides.
The precipitate formed by sulphuretted hydrogen may contain the black mercuric, lead, and copper sulphides, dark-brown bismuth sulphide, yellow cadmium and arsenious sulphides, orange-red antimony sulphide, brown stannous sulphide, dull-yellow stannic sulphide, and whitish sulphur, the last resulting from the oxidation of sulphuretted hydrogen by ferric salts, chromates, &c. Warming with ammonium sulphide dissolves out the arsenic, antimony and tin salts, which are reprecipitated by the addition of hydrochloric acid to the ammonium sulphide solution.
Any residue consists of black mercuric sulphide (and possibly white lead sulphate), in which mercury is confirmed by its usual tests.
Substances which burn with difficulty may be mixed with mercuric oxide in addition to copper oxide.
Mercuric iodide also exhibits dimorphism.
They may also be prepared by the action of mercuric or cupric oxides on alkaline solutions of hydroxylamine (A.
The reagents in common use are: Millon's reagent, a solution of mercuric nitrate containing nitrous acid, this gives a violet-red coloration; nitric acid, which gives a yellow colour, turning to gold when treated with ammonia (xanthoproteic reaction); fuming sulphuric acid, which gives violet solutions; and caustic potash and copper sulphate, which, on warming, gives a red to violet coloration (biuret reaction).
Sandmeyer, Ber., 1887, 20, p. 1494) by the action of copper powder on the double salt formed by the addition of potassium mercuric nitrite to diazonium nitrites; and by the oxidation of primary aromatic amines (E.
Only stannous salts (not stannic) give a precipitate of calomel in mercuric chloride solution.
Compressed dry guncotton is easily detonated by an initiative detonator such as mercuric fulminate.
CYANAMIDE, NC NH 2j the amide of normal cyanic acid, obtained by the action of ammonia on cyanogen chloride, bromide or iodide, or by the desulphurization of thio-urea with, mercuric oxide; it is generally prepared by the latter process.
The hexachloride, Si 2 C1 61 is formed when silicon chloride vapour is passed over strongly heated silicon; by the action of chlorine on the corresponding iodocompound, or by heating the iodo-compound with mercuric chloride (C. Friedel, Comptes rendus, 18 7 1, 73, P. 497).
Primary amines heated with carbon bisulphide in alcoholic solution are converted into mustard oils, when the dithiocarbamate first produced is heated with a solution of mercuric chloride.
Other methods are to place the metal and mercury together in dilute acid, to add mercury to the solution of a metallic salt, to place a metal in a solution of mercuric nitrate, or to electrolyse a metallic salt using mercury as the negative electrode.
Thoulet's solution, an aqueous solution of potassium and mercuric iodides (potassium iodo-mercurate), introduced by Thoulet and subsequently investigated by V.
Rend., 1905, p. 141) has investigated the solutions of mercuric iodide in other alkaline iodides; sodium iodo-mercurate solution has a density of 3.46 at 26°, and gives with an excess of water a dense precipitate of mercuric iodide, which dissolves without decomposition in alcohol; lithium iodo-mercurate solution has a density of 3.28 at 25.6°; and ammonium iodo-mercurate solution a density of 2.98 at 26°.
Rohrbach's solution, an aqueous solution of barium and mercuric iodides, introduced by Carl Rohrbach, has a density of 3.588.
Chlorine monoxide results on passing chlorine over dry precipitated mercuric oxide.
Hypochlorous acid is formed when chlorine monoxide dissolves in water, and can be prepared (in dilute solution) by passing chlorine through water containing precipitated mercuric oxide in suspension.
Precipitated calcium carbonate may be used in place of the mercuric oxide, or a hypochlorite may be decomposed by a dilute mineral acid and the resulting solution distilled.
The latter method has been modified by adding potassium cyanide in slight excess to the solution of the mixed salts, heating for some time and then adding mercuric oxide and water, the whole being then warmed on the water bath, when a precipitate of mercuric oxide and nickel hydroxide is obtained 666, 670).
Double salts of cerous chloride with stannic chloride, mercuric chloride, and platinic chloride are also known.
Priestley in 1774, who obtained the gas by igniting mercuric oxide, and gave it the name "dephlogistigated air."
Oxygen may be prepared by heating mercuric oxide; by strongly heating manganese dioxide and many other peroxides; by heating the oxides of precious metals; and by heating many oxy-acids and oxy-salts to high temperatures, for example, nitric acid, sulphuric acid, nitre, lead nitrate, zinc sulphate, potassium chlorate, &c. Potassium chlorate is generally used and the reaction is accelerated and carried out at a lower temperature by previously mixing the salt with about one-third of its weight of manganese dioxide, which acts as a catalytic agent.
It is readily desulphurized by silver oxide, mercuric oxide or lead oxide.
The dialkyl thioureas when digested with mercuric oxide and amines give guanidines.
Baudrimant, Jahresb., 1880, p. 393); by the action of 50% sulphuric acid on cyanamide: CN NH2+H20= CO(NH 2) 2; by the action of mercuric oxide on oxamide (A.
Urea may be recognized by its crystalline oxalate and nitrate, which are produced on adding oxalic and nitric acids to concentrated solutions of the base; by the white precipitate formed on adding mercuric nitrate to the neutral aqueous solutions of urea; and by the so-called "biuret" reaction.