ANTIMONY.— Tiuoxide. Trichloride. 249
the precipitate. Its colour distinguishes it fromthe sulphur compounds already mentioned.
The commercial pentasulphide is often of a verybright colour; it is prepared by boiling the amorphoustrisulphide with potassium hydrate and ground sul-phur, and after filtering off the liquor, precipitatingby means of an acid in the usual way Or, 4parts of the trisulphide of antimony are boiled with8 of lime and 80 parts of water, the liquor strainedand precipitated by hydrochloric acid in the usualway. Or, 2 parts of the trisulphide may be fused ina crucible with 4 parts of carbonate of potassiumand 1 of sulphur; the residue, when cold, boiledwith 20 parts of hot water; the solution filtered anddecomposed by a large excess of sulphuric acid.
The medicinal effects of this compound are moreactive than those of the kermes, on account of thelarger proportion of teroxide of antimony which itcontains. Its uses are as an alterative in chronicdiseases, particularly cutaneous affections, glandularenlargements, rheumatism, and liver complaints.
Suljdiantimonites .—Trisulphide of antimony com-bines readily with basic metallic sulphides. Manyof these bodies are found as minerals, such as—
Zinkenite,.Pb 2 S,Sb 2 S 3
Myargyrite.Ag 2 S,Sb 2 S 3
Antimonial copper glance,.Cu 4 S,Sb 2 S 3
Jamesonite,.(Pb 2 S) 3 Sb 2 S 3
Feather ore,....(Pb 2 S) 2 Sb 2 S 3
Stephanite,.(Ag 2 S) 6 Sb 2 S 3 , (fee.
Livers of Antimony. —These are the artificial sul-
phantimonites of the alkali metals. They result from
the fusion of trisulphide of antimony with alkalinecarbonates.
Pentasulphide of antimony is a strong sulphuracid. It forms salts with most of the basic metallicsulphides, which have the composition (M 9 S) 3 Sb 2 S 6or M 3 SbS 4 .
Antimonious Oxide. Trioxide of antimony (Sb 2 0 3 ),valentinite, white antimony, antimony bloom. —This sub-stance is found as a mineral. It occurs in veins ofthe primary rocks in Bohemia, Saxony, and Hun-gary , in shining white crystals of the trimetric sys-tem, and also in Algeria in regular octahedra. Theartificial crystalline trioxide is likewise found to bedimorphous. This compound was known to BasilValentine , who called it fores antimonii. In com-merce it is termed indifferently protoxide, sesquioxide,and flowers of antimony.
It may be prepared in several ways. 1. On heat-ing metallic antimony to the point of its combustionit burns with a bluish light, and if the crucible bereclined to one side to admit a current of air, smallacicular crystals of trioxide will be observed on theupper part. 2. By adding metallic antimony inpowder to sulphuric acid, evaporating the liquidto dryness, and then washing the dry mass, firstwith water and next with a weak solution of car-bonate of soda, for the purpose of removing the lastportions of sulphuric acid ; after completely washingthe residue a white powder remains, which is trioxideof antimony. 3. By digesting finely-ground greysulphide of antimony in about four times its weightVOL. i.
of hydrochloric acid, trichloride of antimony isformed and sulphide of hydrogen escapes with effer-vescence, the former of which is decomposed bycarbonate of soda into trioxide of antimony, whichprecipitates, while carbonic acid is liberated, and thesoda is converted into chloride of sodium by thechlorine of the antimonial compound.
The precipitated trioxide is collected upon a filter,washed well with water, and dried. For pharma-ceutical purposes the Dublin college recommends thetreatment of 20 parts of the powdered grey sulphideof antimony with 100 parts of hydrochloric acid and1 of nitric acid; the acid and powder must be slowlybrought together, and a gentle heat applied for sometime, which may be afterwards increased, and thesolution left to digest as long as any effervescence orescape of sulphuretted hydrogen is observed; andthen the whole is to be boiled for an hour, the liquorfiltered when cold, and the filtrate received in avessel containing 1 gallon of cold water, which pre-cipitates the basic trichloride of antimony. Theoxychloride is collected, and washed with watertill the washings cease to evince an acid reaction withlitmus paper. During the washing of the precipitatethe water is decomposed, its oxygen being retainedby the antimony and antimonious oxide (Sb 2 0 3 )formed, hydrochloric acid being given off.
Dumas directs the preparation of trioxide of anti-mony to be conducted as follows:—Heat pulverizedantimony in a shallow vessel exposed to the air; whenthe oxidation has advanced, the metal takes fireand becomes incandescent, antimonic oxide (Sb 2 0,.),mixed with some of the metal, being produced; thewhole of the compound is now transferred to acrucible, in which it is heated to fusion, when theantimonic oxide is reduced to the state of trioxideby the excess of metal, which is found, with thefused mass, in a button at the bottom.
Trioxide of antimony is a white powder, fusible,and volat.le at a red heat; when heated in closevessels it suffers no change, but is partly sublimed,and condenses in acicular or octahedral crystals onthe cover, or upper part of the pot.
If the trioxide be kept in fusion, with contact ofair, it is converted into pentoxide (antimonic oxide,Sb 2 0 5 ) ; but if the air be excluded, it concretesinto a silky crystalline mass, presenting a greyishappearance.
Water dissolves oxide of antimony in small quan-tity. Nitric acid and chlorate of potassium rapidlyconvert the trioxide into pentoxide ; sulphur decom-poses it in the heat into trisulphide, with the forma-tion of water; and when heated to redness withcharcoal, metallic antimony is obtained. Tartaricacid readily dissolves the antimonious oxide; acidtartrate of potassium acts similarly. In each casetartar emetic is produced.
Trichloride of Antimony. —Butter of Antimony(SbCl g ) is used to some extent in medicine, chieflyas a caustic.
On dissolving sulphide of antimony in hydrochloricacid, as before explained, trichloride of antimony isformed, with the evolution of sulphuretted hydrogen.