408
ELEMENTS OF MATERIA MEDICA.
though imperfect, may perhaps assist the student in comprehending theforegoing changes: —
reagents.
C Nitric A d .
'Nitrogen\Nitrogen< Oxygen
Nitrate of
\
( Oxygen
\ Potash...
^ Potash...
5 Oxygen .
\ Potassium
Hydrochloric Acid.
( HydrogenX Chlorine .
Sesquisulphuret Antimony. {Sesquisulphuret of Antimony.
RESULTS.- Nitrogen.-Binox. Nitrog.
Sulphate Potash.Water.
Sesquiox. Antim.Sesquisulpht.Antim.
The reacting equivalents have been omitted in the above diagram : butthe results may be explained by assuming that 6 equivalents of nitrate,7 equivalents of sesquisulphuret, and ly equivalents of hydrochloric acid,are employed. The products will be 6 eqs. of binoxide of nitrogen,4y eqs. of sulphate of potash, ly eqs. of water, 1| eqs. of chloride ofpotassium, 3 eqs. sesquioxide of antimony, and 4 eqs. sesquisulphuret.
The changes in the second stage of the process are readily compre-hended : two equivalents or 154 parts of sesquioxide of antimony com-bine with one equivalent or 180 parts of dry bitartrate of potash, to formone equivalent or 334 parts of dry emetic tartar, which, in crystallizing,unite with three equivalents, or 27 parts of water. The sesquisulphuretis unacted on by the bitartrate of potash.
REAGENTS.
PRODUCTS.
1 eq. dry Bi- c 1 eq. Tart. Acid_66
tartrate •] 1 eq. Tart. Acid .. ..66Potash 180 * 1 eq. Potash. 48
Oxysulphuret $ 2eq.Sesquiox.Ant.154Antimony £ — Sesquisulp.Ant. ...
1 eq. Ditart.Antim. — 220
l
eq. crysrf.An-tim. -tartr. ofPotash. ..361
-Sesquisulp 1 . Antim.
Properties. —Emetic tartar crystallizes in white, transparent, inodo-rous, rhombic octahedrons, whose lateral planes are striated. By expo-sure to the air they become opaque, probably by giving out an equivalentof water. Their taste is feebly sweetish, then styptic and metallic. Theydissolve in 14 or 15 parts of water at 60° F. (12-^ at 70°, Brandes),—and in 2 parts (2 T y 5 parts, Brandes) at 212°. Their aqueous solutionslightly reddens litmus and undergoes decomposition by keeping, likethat of tartaric acid and most tartrates. Alcohol will not dissolve thissalt. By calcining emetic tartar in close vessels we obtain a pyrophoricalloy of antimony and potassium. They decrepitate in the fire.
Characteristics. —Heated in a porcelain or glass capsule it chars:shewing it contains an organic substance (tartaric acid.) If the charredsalt be heated in a glass tube by a blowpipe, globules of antimony areobtained.
If a stream of hydrosulphuric acid gas be transmitted through a waterysolution of emetic tartar (vide fig. 65, p. 409), the latter becomes orange-red:if a small quantity of hydrochloric acid be then added, a flocculent orange-red precipitate (hydrated sesquisulphuret of antimony) takes place. Thisprecipitate is to be collected and dried, and introduced into a green glasstube. Then transmit a current of hydrogen gas over it, and after a fewminutes apply the heat of a spirit lamp to the sesquisulphuret; hydrosul-