ARSENIC. 
§§ 738-741-] 
559 
case recorded in the British Medical Journal, November 4, 1876, there 
were none of the usual symptoms of gastric irritation, but loss of memory 
of recent acts, drowsiness, and giddiness. From the recorded cases, the 
more or less distinctive symptoms are (1) lumbar pain, (2) bloody urine, 
(3) jaundice. 
§ 738. The Sulphides of Arsenic. —Of the sulphides of arsenic, two 
only, realgar and orpiment, are of any practical importance. Realgar, 
As 2 S 2 = 214 ; specific gravity, 3-544 ; composition in 100 parts, As 70*09, 
S 29-91 ; average composition of commercial product, As 75, S 25. 
Realgar is found native in ruby-red crystals, and is also prepared arti¬ 
ficially by heating together 9 parts of arsenic and 4 of sulphur, or 198 
parts of arsenious anhydride with 112 parts of sulphur, 2As 2 0 3 + 7S = 
2As 2 S 2 + 3S0 2 . It is insoluble in water and in hydrochloric acid, but 
is readily dissolved by potassic disulphide, by nitric acid, and by aqua 
regia. It is decomposed by caustic potash, leaving undissolved a brown 
sediment (As 12 S), which contains 96-5 per cent, of arsenic. The dis¬ 
solved portion is readily converted into arsine by aluminium. 
§ 739. Orpiment, or Arsenic Trisulphide. —As 2 S 3 = 246 ; specific 
gravity, 3-46 ; composition in 100 parts, As 60-98, S 39-02 ; found 
native in crystals ; presents itself in the laboratory usually as a brilliant 
yellow amorphous powder, on passing sulphuretted hydrogen through an 
acid solution of arsenious acid or an arsenite. It is very insoluble in 
water (about one in a million, Fresenius), scarcely soluble in boiling con¬ 
centrated hydrochloric acid, and insoluble generally in dilute acids. Red 
fuming nitric acid dissolves it, converting it into arsenic and sulphuric 
acids ; ammonia and other alkaline sulphides, the alkalies themselves, 
alkaline carbonates, bisulphide of potassium, and aqua regia, all dissolve 
it readily. In the arts it is used as King’s yellow (see p. 562). Tanners 
also formerly employed a mixture of 90 parts of orpiment and 10 of 
quicklime, under the name of Rusma, as a depilatory ; but the alkaline 
sulphides from gasworks are replacing this to a great extent. 
§ 740. Haloid Arsenical Compounds.—The Chloride of Arsenic, 
AsC1 3 = 181-5 ; specific gravity liquid, 0°, 2-205 ; boiling-point, 134° 
(273-2° F.), is a heavy, colourless, oily liquid, which has been used as 
an escharotic in cancerous affections (principally by quacks). I 11 one 
process of detecting and estimating arsenic, the properties of this sub¬ 
stance are utilised (see p. 598). It is immediately decomposed by water 
into arsenious and hydrochloric acids. 
The Iodide of Arsenic (Asl 3 ) is used occasionally in skin diseases, but 
is of little interest to the analyst; it is commonly seen in the form of 
brick-red brilliant flakes. 
§ 741. Arsenic in the Arts. —The metal is used in various alloys ; 
for example, speculum metal is made of tin, copper, and a little arsenic ; 
white copper is an alloy of copper and arsenic ; shot is composed of 1000 
