SULPHATES.

1219

ijii | ( .. tno .‘ n Point in the preparation of sugar of lead, is to use a strong acid ; otherwiseco) 0r ] llrne a nd acid are wasted in concentrating the solution. This salt crystallizes inh ui transparent, four and six sided prisms, from a moderately concentrated solution ;bee n °r 1 a stronger solution, in small needles, which have a yellow cast if the acid has? r avitv?r 1 ' 5 ; 11 has no smell, a sweetish astringent metallic taste, a specific

ite^l J °f 2-345; it is permanent in the air at ordinary temperatures, but effloresces whenpOtyj to with the loss of its water of crystallization and some acid, falling into alj ,j ^ r > which passes, in the air, slowly into carbonate of lead. The crystals dissolve inj S Uteir weight of water at 60°, but in much less of boiling water-, and in 8 parts ofcol 0r ° • The solution feebly reddens litmus paper, but has an alkaline reaction upon the27 -or °‘ 'Holets and turmeric. The constituents of the salt are, 58-71 oxyde of lead,A c acw ' c acid, and 14-21 water, in ICO.

a le of lead is much used in calico-printing. It is poisonous, and ought to be pre-Tti an< ^ handled with attention to this circumstance.at 0t)) ere ate two subacetates of lead ; the first of which, the ler-subacetate, has threeext r s 'T base to one of acid, and is the substance long known by the name of Goulard’sU|i 0n c • h may be obtained by digesting with heat a solution of the neutral acetate,Pure litharge or massicot. The solution affords white crystalline scales, which do

hot

bl e aste so sweet as sugar of lead, dissolve in not less than 30 parts of w'ater, are insolu-hcid ^ a ' c °hol, and have a decided alkaline reaction upon test paper. Carbonicin transmitted through the solution, precipitates the excess of the oxyde of lead,' v hj[ e e . state of a carbonate, a process long ago prescribed by Thenard for makingit , s This subacetate consists of 88-66 of oxyde, and 13-34 acid, in 100 parts.

SUrgg^'Plt’yed for making the orange sub-chromate of lead, as also sometimes in

in e ^ Sx ' su i>acetate, containing 6 atoms of base, may be obtained by adding ammonia'v a(er Ce ?s to a solution of the preceding salt, and washing the precipitate with dilute'Vhter V* am monia. A white powder is thus formed, that dissolves sparingly in coldisit ut gives a solution in boiling water, from which white silky needles are de-

Posii

’ted t - - - -

SUl t>u 1 cons ’ sts of 92-86 oxyde, and 7-14 acid.

”ATES, are saline compounds of sulphuric acid with oxydized bases. The' ns °lubt t 9 Uant ’’y of them present in any solution, may be detected by the precipitate,Th e y e in nitric or muriatic acid, which they afford with nitrate or muriate of baryta.

‘Ihor of.t.-’ --—- -■— -j -»-

a rnm 0n ■ 1,6 gas-works with sulphuric acid; and it is employed for making carbonate of

^LPtr ® ee - Ammonia an< I Sal Ammoniac.

‘he e„T H ATE OF BARYTA, is the mineral called heavy-spar, which frequently forms

POTASSA, is alum,salt sometimes formed by saturating the ammonia

Pu- 6 01 rein-stone of lead and other metallic oars. .

lirtu'L.. HATE OF COPPER, Roman or Blue Vitriol (Vitriol de Chypre,Vr.

Kup-

^ Germ.), is a salt composed of sulphuric acid and oxyde of copper, and may be“I boiling'the concentrated acid upon the metal, in an iron pot. It is, how-

r Ut,

5 * ____

nj itural product of many copper mines, fiom which it flows out in the form of aS Ler > being the result of the infiltration of water'over, copper pyrites, which hascone ° x ^ en ated by tong exposure to the air in subterranean excavations. The liquidbi ^^irated by heat in copper vessels, then set aside to crystallize. The salt formsfour-sided tables, of a fine blue color; has a spec, gravity of 2-J04; an acerb,C °Wnf b e , metallic taste; and, wl-.en swallowed, it causes violent vomiting. It be-N** * bale dirty blue, and effloresces slightly, on long exposure to the air; whens ?lv„ s , heated, it loses 36 per cent, of water, and falls into a white powder. It dis-l '° n has 4 parts of water, at 60°, and in 2 of boiling water, but not in alcohol; the solu-* lrif l ;r atl acid reaction upon litmus paper. AVhen strongly ignited, the acid flies off’,>|> er bla ck oxyde of copper remains. The constituents of crystallized sulphate ofNoti^'^yde, 31-80; acid, 32-14; and water, 36-06. Its chief employment in' S * n dyeing, and for preparing certain green pigments. See Scheele’s andi ir gra- Fl,STH Green" In France , the farmers sprinkle a weak solution of it uponVt s . lns and seeds before sowing them, to prevent their being attacked by birds and

^tee/^ATE OF IRON, Green vitriol, Copperas (Conperose verte, Fr.; Eisen-vitriol,k r ° to Xyd y u fiisenoxydul, Germ.), is a crystalline compound of sulphuric acid andh 5s e, 29 .q,? p * ron S hence called, by chemists, the protosulphate ; consisting of, 26-10 ofs^Eyde 50 °^ ac ’dj and 44-00 of water, in 100 parts; or of 1 prime equivalent ofli l b g jf ~t“ I °f acid, 40, 7 of water, 63,=139. It may be prepared by dis-

<: to saturation in dilute sulphuric acid, evaporating the solution till a pel-

0llll)1 ercp S - Upon its surface, and setting it aside to crystallize. The copperas ofls made in a much cheaper way, by stratifying the pyrites found in the coal