350 BISMUTH 



viously boiled, and coolod out of contact of the air ; this metal is then treated -with 

 carbonate of ammonia, and the precipitate which is loft, after washing awl ignition, 

 is then weighed. The total loss of the metallic load employed indicates how much 

 oxide of lead must bo subtracted from the total weight of the protoxide of load 

 obtained. 



BISMUTH, OXIDES OF. There are two well-defined oxides of bismuth the teroxide 

 and the pentoxido, with an unimportant intermediate oxide. Of these compounds it is 

 only necessary to notice the teroxide or bismuthous oxide BiO" (B1 2 O S ). This is found 

 native as bismuth-ochro, and may be readily formed by exposing the metal to a red- 

 white heat in a muffle, when it takes fire, burns with a faint blue flame, and emits fumes 

 which condense into a yellow pulverulent oxido. But an easier process is to ignite the 

 nitrate or carbonate. The oxide thus obtained has a straw-yollow colour, and fuses 

 at a high heat into an opaque glass of a dark-brown or black colour; but which, 

 becomes loss opaque and yellow after it has coolod. Its specific gravity is as high 

 as 8-211. It consist* of 89'87 of metal and 10-13 of oxygen in 100 parts. The only 

 salt of this oxido used in the arts is the nitrate, which is obtained by dissolving metallic 

 bismuth in warm nitric acid. On largely diluting a solution of the nitrate with water, 

 a sub-nitrate or basic-nitrate is precipitated. This precipitate was termed by the 

 older chemists, ' magestery of bismuth,' .and is now sometimes called pearl-white, and 

 is employed as a flux for certain enamels, as it augments their fusibility, without 

 imparting any colour to them. Hence it is used sometimes as a vehicle of the colours 

 of other metallic oxides. When well washed, it is employed in gilding porcelain; 

 being added in the proportion of one-fifteenth to the gold. But pearl-white is most 

 used by ladies, as a cosmetic for giving a delicate whiteness to a faded complexion. 

 It is called blanc defard by the French. If it contains, as bismuth often does, a little 

 silver, it becomes grey or dingy-coloured on exposure to light. Another sort of pearl- 

 powder is prepared by adding a very dilute solution of common salt to the above nitric 

 solution of bismuth, whereby a pulverulent sub-chloride of the metal is obtained in a 

 light flocculent form. A similar powder of a mother-of-pearl aspect may be formed 

 by dropping dilute muriatic acid into the solution of nitrate of bismuth. The arsenic 

 always present in the bismuth of commerce is converted by nitric acid into arsenic 

 acid, which, forming an insoluble arsenate of bismuth, separates from the solution 

 unless there be such an excess of nitric acid as to re-dissolve it. Hence the medi- 

 cinal oxide, prepared from a rightly-made nitrate, can contain no arsenic. If wo 

 write with a pen dipped in that solution, the dry invisible traces will become legible 

 on plunging the paper in water. 



The nitrate of bismuth, mixed with a solution of tin and tartar, has been employed 

 as a mordant for dyeing lilac .and violet in calico-printing. 



When the oxide is prepared, by dropping the nitric solution into an alkaline lye 

 in excess, if this precipitate is well washed and dried, it forms an excellent medicine ; 

 and is given, mixed with gum tragacanth, for the relief of cardialgia, or burning and 

 spasmodic pains of the stomach. 



This sub-nitrate of bismuth is now commonly employed as a remedial agent, under 

 circumstances which are especially liable to attack the emigrant; it is, therefore, 

 thought advisable to give some account of its action. The following is extracted from 

 Percira's ' Elements of Materia Medica,' by Bentley and Redwood : 



'Physiological Effects, In small doses it acts locally as an astringent, diminishing 

 secretion. On account of the frequent relief given by it in painful affections of the 

 stomach, it is supposed to act on the nerves of this viscus as a sedative. It has also 

 been denominated tonic and antispasmodic. Vogt says, that when used as a cosmetic, 

 it has produced a spasmodic trembling of the face, ending in paralysis. 



' Large medicinal doses disorder the digestive organs, occasioning pain, vomiting, 

 purging, &c. ; and sometimes affecting the nervous system, and producing giddiness, 

 insensibility, with cramps of the extremities. On the other hand, M. Momeret states, 

 after several years' trial of this medicine, that it may be given in much larger doses 

 than are usually administered, and that it is then of the greatest value in gastro- 

 intestinal affections, especially those attended with fluxes. 



' Therapeutics. It has been principally employed in those chronic affections of the 

 stomach which are unaccompanied by any organic disease, but which apparently depend 

 on some disordered condition of the nerves of this viscus ; and hence, the efficacy of 

 the remedy is referred to its supposed action on these parts. It has been particularly 

 used and recommended to relieve gastrodynia and cramp of the stsomach, to allay 

 sickness and vomiting, and as a remedy for pyrosis or water-brash. In the latter 

 disease I give it in the form of a powder, in doses of twenty grains thrice daily, in 

 conjunction with hydrocyanic acid mixture, and the patient rarely fails to obtain 

 marked benefit from its use. It is also used in ulcer of the stomach. Dr. Thoophilus 

 Thompson recommends it in doses of five grains, combined with gum arabic and 



