B I S 



part of the procefs, is remarkably more difficult of rediiAion 

 than any of the pvvc oxyda of ^ 5. 



2. Sulphureous acid is incapable of attacking rretallic 

 bifmuth, but readily combines with its oxyd, forminEr a 

 white iiifoluble fulphite of a fulphureous flavour, reducible 

 into metallic globules before the blowpipe, decompofable 

 with effcrvefcence by fulphuric acid, and when dillilled, 

 giving out its acid, a mafs of pure white oxyd remaining 

 behind. 



3. Nitric acid afts upon bifmuth in a remarkably violent 

 manner. If the metal is in powder, and'the acid fomewhat 

 concentrated, at the inilant of their mixture, even without 

 the aflillancc of heat, a rapid decompofition of the acid 

 lakes place, accompanied with the production of nitrous 

 gas, azot, and fometimes of ammonia ; and the bifmuth is 

 converted into a white oxyd. If the acid is previoufly di- 

 luted with an equal weight of water, and the bifmuth is 

 added gradually in fmall pieces, the decompofition goes on 

 more quietly, the metal is diffolved in proportion as it 

 oxydates, and the acid may be made to take up nearly half 

 its weight of bifmuth. By cautioufly adding to this folution 

 an equal bulk of dillilled water (each portion being well 

 mixed with the whole mafs by ftirring, before the addition 

 of a fuccceding portion), a black pulverulent precipitate 

 takes place, w^.ich' has not yet been analyfed, but ha? been 

 taken tor iulphur or charcoal. If the acid made ufe of is 

 ftill more dilute, confifting, for example, of four parts of 

 water, and one of nitric acid, the black matter is not dif- 

 folved. Nitrat of bifmuth, when thus purititd, is clear and 

 colourlefs, and by gentle evaporation cryftallizcs in the form 

 of flattened rhomboids, or comprtffed tetrahedral prifins 

 terminated by three fided pyramids. This fait, when ex- 

 pofed to a dry air, is confiderably efflorefcent ; but in a 

 humid air, becomes covered with a white, fomewhat moiil 

 coating of oxyd. When thrown on hot coals, it detonates 

 feebly, giving out faint red fparks, and leaves behind a 

 greenifh yellow oxyd of difficult reduftion. If a crj-ftal of 

 nitrated bifmuth is thrown into fome pure water, it imme- 

 diately becomes covered with a white opaque oxyd ; but the 

 decompofition of this fait is more ftriking, if a folution of it 

 is made ufe of. For this purpofe, let a jar be nearly filled 

 with clear rain water, and drop into it nitrat of bifmuth as 

 long as any precipitation takes place, then mix the whole 

 by agitation, and let it ftand for an hour to fettle. The 

 bottom of the veffcl will now be covered with a nne heavy 

 powder of a dazzling white, which, when repeatedly walhed 

 and dried, is pure oxyd of bifmuth, formerly called itiagi/lery 

 ef I'ifmuth, and well known as a cofmetic under the name 

 of blanc de furd. This preparation, if made with pure 

 nitn'c acid, and well wafhed, is of a dead white ; but if a 

 little muriatic acid is mixed with the nitric, and the preci- 

 pitate is wafiied with ^ fmall portion of coLl water, it will be 

 in the form of minute glittering fcales with a beautiful 

 pearly luftre, and is then called by the French blunc de perks. 

 In both Hates it is extenfively employed, particularly by the 

 French ladies for whitening the flvin, but is fubjeft to turn 

 grey, brown, and even black, by any hydrogenous and ful- 

 phuieous vapours. This oxyd of bifmuth does not appear 

 to retain any nitric acid ; and its component parts are fixed 

 by Bergman at 77 of metal, and 23 of oxygen ; but, by the 

 more accurate experiments of Klaproth, its contents are af- 

 certained to be 81 of metal to 19 of oxygen. Nitrated bif- 

 muth is not, however, totally dtcompofable by water ; for 

 the clear fluid, that is fcparated by filtration from the oxyd, 

 may llili be made to yield a precipitate by a carbonated 

 alkali, muriatic acid, or muriated ammonia. Klaproth 

 found (Analyt. Eff. vol. i. p. 557- )> that 100 grains of \)\i. 



B I S 



muth, diffolved in nitric acid, yielded with water 88 grains 

 of oxyd, and 35 more were obtained from the diluted folu- 

 tion, by the action of muriatic acid added in drops as long 

 as any precipitate enfued. This oxyd is very eafily reduced 

 by fufion in a covered crucible, with a little nitre and 

 tartar. 



4. Bifmuth in the metallic ftate is afted upon with diffi- 

 culty by muriatic acid, even when it is concentrated and 

 afiilfed by heat. During the digeftion, a fmall quantity of 

 fetid hydrogen gas is given out ; and, by flow evaporation, 

 fmall deliqucfcent needle-diaped cryftals are depofitcd of 

 muriat of bifmuth. This fait, however, may be obtained 

 in much greater quantity, and more eafily, by fubftituting 

 the oxyd of bifmuth for the pure metal. If the falina 

 mafs, which remains behind after evaporation to drynefs, is 

 dillilled in a glafs retort, nearly the whole of it comes over 

 at a moderate heat, and concretes into a foft white mafs, 

 called formerly liit'.er of Ifmuth. Butter of bifmuth, like 

 butter of antimony, is intenfcly cauftic to the talle, dtrhqui- 

 ates in a moid air, and when dropped into water, is decom- 

 pofed, a fine white oxyd being precipitated. 



5. Liquid cxy-muriatic acid afts upon metallic bifmuth 

 with coiifu'embly more energy than muriatic acid does : 

 the metal is oxydited without the difengagement of hydro- 

 gen, and the ri-fulr is muriat of bifmuth. It is probable, 

 that hy fuhft't^itiiig tht oxyd of bifmuth for the pure metal, 

 oxy muriat of bifmuth might be produced: this, however, is 

 not as yetconfirratd by experim.ent. If bifmuth, previoufly 

 reduced to fine powder, is poured into oxymuriatic acid 

 gas, the metal is inftantly ignited and oxydated, and falls in 

 a fhower of fire to the bottom of the vefTcl. 



6. Tindture of galls, or gallic acid, precipitates bifmuth 

 of a greenifh colour from its folution, as pruffiated potalk 

 does of a yellowifli colour. 



7. There is fcarcely any thing known concerning the 

 other bifmuthic falts. They are formed by digefling the yel- 

 low oxyd in the various acids that have not been already men- 

 tioned, and are for the mod part but little foliible in water. 

 The proportions of their ingredients have not been afcer- 

 tained with any accuracy, nor are they applied to any ufe. 



J 7. Adion of the Alkalies and Earths on Bifmuth. 



The fixed alkalies have no cffctl on metallic bifmuth, but 

 unite both in the humid and dry way with its oxyd. Am- 

 monia is faid to acquire a greenifh yellow colour by digeftion 

 with the metal when pulverized, and certainly diffolves its 

 oxyd in confiderable proportion. The aftion of the earths 

 upon bifmuth is unknown, except that fiiex and oxyd of 

 bifmuth combine by fufion into a clear grecnilli yellow glafs. 

 § 8. AS'ton of the Neutral Salts on Bifmuth. 



None of the neutral falts in folution appear to exert any 

 affinity on bifmuth or its oxyds ; but, in a dry heat, many 

 of them are decompofed by it. 



Nitre, being mixed with pulverized bifmuth, and projefled 

 into a red hot crucible, is decompofed with a flight deto- 

 nation ; the bifmuth becomes oxydated, and then unites in 

 part with the alkaline bafe of the nitre. 



Muriat of foda, according to Pott, is in fome degree de- 

 compofable by metallic bifmuth. This faft, however, is not 

 confirmed by later chemifts ; and it is probable, that the fait, 

 which Pott made tife of, was not free from muriated mag- 

 nefia, and that the bifmuth was partly oxydated. 



Muriated ammonia is totally decompofable by oxyd cf 

 bifmuth. On the firll impreffion of the fire, ver)- pure am- 

 moniacal gas is difengagtd ; and by a low red heat, the 

 muriated bifmuth rifes in the form of a thick white vapour, 

 which concretes, in the receiver and neck of the retort, into 

 butter of bifmuth ; if the oxyd of bilinuth is in verj' fmall 



proportiou 



