682 POISONS : THEIR EFFECTS AND DETECTION. [§ 867 . 
parts of oxalate and cyanide of potassium should be well mixed with 
the cinnabar, and treated as described at p. 699 ; by this means the whole 
of the metallic mercury is readily obtained. 1 
The sulphide, oxidised to sulphate by aqua regia, may also be reduced 
to mercury by the method of Fran§ois {Compt. Rend., 1908). This 
consists in placing the mercurial salt, with a little potassium iodide, in 
a conical flask with 1 grm. of zinc filings and 10 c.c. of 2N sulphuric 
acid. After half an hour, a second quantity of zinc and acid is added, 
and a third lot after an hour. After twenty-four hours the liquid is 
decanted through a filter and the residue washed. To this residue of 
zinc-mercury is added gradually 25 c.c. of dilute hydrochloric acid, and 
digested for twenty-four hours. At the end of this time the liquid is 
decanted and replaced by 25 c.c. of fuming hydrochloric acid, which 
within twenty-four hours dissolves all the zinc and leaves the mercury 
as a clean globule. An objection to the process is the length of time, 
viz. three days, in attaining the desired result. 
§ 867. Mercury in the Arts. —The use of mercury in the arts is so 
extensive that anyone in analytical practice is almost certain occasion¬ 
ally to meet with cases of accidental poisoning, either from the vapour 2 
or some of its combinations. # 
Quicksilver is used in the extraction of gold, the silvering of mirrors, 
the construction of barometers and various scientific instruments and 
appliances ; also for the preservation of insects, and occasionally for their 
destruction. 3 An alloy with zinc and cadmium is employed by dentists 
for stopping teeth ; but there is no evidence that it has been at all 
injurious, the mercury, probably, being in too powerful a state of com¬ 
bination to be attacked by the fluids in the mouth. 4 Cinnabar has 
also been employed to give a red colour to confections, and it may be 
found in tapers, cigarette papers, and other coloured articles. The 
nitrate of mercury in solution finds application in the colouring of horn, 
in the etching of metals, in the colouring of the finer sorts of wool, and 
in the hat manufacture. 
1 Dr Sutro has published a case (quoted by Taylor) in which the vapour of 
vermilion, applied externally, produced poisonous symptoms ; yet, according to 
Polak, the Persians inhale it medicinally, smoking it with tobacco, catechu, mucilage, 
etc., the only bad effect being an occasional stomatitis.—Eulenberg, Gewerbe Hygiene, 
p. 741. 
A singular case is cited by Tardieu ( Etude med.-legale sur VEmpoisonnement ), 
in which a man, supposing he had some minerals containing gold, attempted the 
extraction by amalgamation with mercury. He used a portable furnace (for the 
purpose of volatilising the mercury) in a small room, and his wife, who assisted him, 
suffered from a very well-marked stomatitis and mercurial eruption. 
3 korty-three persons were salivated from fumigating rooms with mercury for the 
purpose of destroying bugs (Sonnenschein’s Handbuch, p. 96). 
4 More danger is to be apprehended from the vulcanised rubber for artificial 
teeth ; and, according to Dr Taylor, accidents have occurred from the use of such 
supports or plates. 
