MERCURY. 
§ 892 .] 
distilled into the capillary portion. The capillary tube is then cut off, 
and crushed in a reagent glass containing 5 c.c. of dilute nitric and 
sulphuric acids. The mixture is warmed for an hour on the water-bath, 
and then transferred to a watch-glass—bringing the whole up to 10 c.c. 
by a 5 per cent, solution of potassic sulphate. This solution is submitted 
to the electrolysis of a platinum-gold couple, made of gold and platinum 
wire. The gold wire weighs about 25 mgrms., and has a length of 18-20 
cm., with a diameter of 0-1 mm. The gold wire is weighed carefully in 
a Nernst 1 balance both before and after the electrolysis ; in each case it 
is carefully dried. 
According to Bruno Bardach ( Chem . Centr., 1901), mercury in the 
urine may be separated and estimated as follows :—250-1000 c.c. of the 
urine are mixed with 0*8 grm. of finely divided egg albumin ; 5-7 c.c. 
of 30 per cent, acetic acid are added, and the albumin precipitated on 
the water-bath. The precipitate contains all the mercury ; it is filtered 
off and dissolved in 10 c.c. of hydrochloric acid of specific gravity T19. 
This solution is heated for forty-five minutes with a clean copper spiral in 
the water-bath. The spiral is washed with water, alcohol, and ether, 
carefully dried between filter-paper, and then heated in a long glass 
tube with a particle of iodine. The yellowish-red iodide of mercury, if 
present, will condense in the colder part of the tube. 
Hans Buchtala ( Zeit. physiol. Chem., 1913) detects and estimates 
mercury in urine by evaporating the urine down with potassium chlorate 
and hydrochloric acid. The filtered liquid is submitted to electrolysis, 
using a gas carbon anode and a gold cathode ; the mercury is deposited 
on the latter, which, after being rinsed and dried, is weighed, then the 
mercury is volatilised, and the cathode again weighed; the difference 
gives the weight of the mercury. 
§ 892. Estimation of Mercury. —All pharmaceutical substances 
containing mercury, as well as the sulphide prepared in the wet way, 
and minerals, are best dealt with by obtaining and weighing the metal 
a 
in the solid state. The assay is very simple and easy when carried out 
on the method that was first, perhaps, proposed by Domeyko. A glass 
tube (which should not be too thin), closed at one end, is bent as shown 
in the figure ; the diameter should be about three lines, the length from 
7 to 8 inches, the shorter arm not exceeding 2 inches. The powdered 
1 The Nernst balance (Ber., xxxvi., 1903) is a micro-balance with torsional control, 
having a sensitiveness of -038 mgrm. per scale division, and capable of being read to 
division. 
