STR

STR

( 343 )

to the air it fcon abforbs moifture ami fulls topieces, and in a few days after becomes faturatedwith carbonic acid. It water is poured upon itwhen recently calcined, the fluid is eagerlyabforbed, a copious extrication of heat takesplace, and the mafs falls into a bulky powder.Strontian is not very l'oluble in cold water, anounce of this fluid at 6o» taking up no morethan 2.7 grs. a This folution is perfe&ly clearand limpid j it tallies like limewater and changesvegetable blues green like the other alkalinefubftances. On expofure to the air it becomescovered with a pellicle of regenerated carbonatof ftrontian, which being removed or falling tothe bottom, another fucceeds, and fo on till thewhole of the earth is precipitated in the ftate ofcarbonat. Boiling water however takes up amuch larger proportion of ftrontian than colddoes, in confequence of which as the folutioncools it depofits the excefs of this earth in acryftalline ftate. The forms of thefe cryftalsare quadrangular plates either plane or bevilledat the edges, or cubes or parallelopipeds.

Thefe cryftals by expofure to the air becomeof an opake white colour, and foon fall to pow-der: by this change they lofe about 10 per cent,notwithftanding the large quantity of carbonicacid that they imbibe: this loi's is entirely water,the recent cryftals containing full 68 per cent,of this ingredient. Of thefe cryftals one ounceof water at 6o° will diflblve 8.5 grs. and thefame quantity when boiling will take up no lefsthan 218 grs.

Strontian combines with all the acids, form-ing with them neutral falts, which though theybear a general refemblance to thofe of barytes,yet differ from them in various particulars, foran account of which we refer to the faltsthemfelves.

Silex and alumine are rendered foluble inwater by means of ftrontian in the fame manneras by the fixed alkalies and barytes, only alarger proportion is required of ftrontian thanof the reft. Sulphur combines with ftrontianby fufion, into a fulphuret, or by boiling witha folution of this earth, into a hydrofulphuret.The fulphuretted hydrogen that is difengagedfrom either the one or the other on the additionof muriatic acid, carries off with it a littleftrontian, and in confequence burns with a redpurple flame inftead of the blue flame of purefulphuretted hydrogen.

. Alcohol takes up a fmall proportion of ftron-tian, and in confequence burns with a purple

* Hope, in Edin, Phil.

flame: this character in particular diftinguifhesit compleatly from barytes which communicatesa pale yellow colour to the flame of alcohol.

Strontian whfcn expofed to the blowpipe isnot fufible as barytes is, but it. emits during theadtion of the flame an intenfely dazzling whitelight. For further particulars of refemblanceand difference between thefe two earths, feeBarytes .

The order of affinity between ftrontian andthe feveral acids is thus ftated by Dr. Hope:fulphuric, oxalic, tartaric, fluoric, nitric, mu-riatic, fuccinic, phofphoric, acetic, arfenic,.boracic, carbonic.

The affinity of barytes for the acids appearsto be in all cafes greater than that of ftrontianfor the fame: but this latter on the other handgenerally takes the precedence of the fixedalkalies, efpecially where the refulting ftrontianfait is much lefs foluble than the correfpondingone of potafh or foda. But in the attractionfor nitric, muriatic, acetic, and fuccinic acids,the fixed alkalies are confidered as fuperior toftrontian. The decompofition however whichthey are able to effect of thefe ftrontitic falts isvery imperfect, as was firft fhown in the cafeof muriatic acid by Dr. Hope. This ablechemift difl’olved 200 grs. of native carbonat offtrontian in muriatic acid diluted with an equal'bulk of water, and when the folution wascompleat, he added an excefs of liquid potafli,but no more than 24 grs. of ftrontian wereprecipitated; he then poured in carbonatedpotafh, and 170 grs. of carbonated ftrontianwere obtained. The fame experiment wasrepeated, except that the cauftic potafli wasdropped in very flowly, by which procefs 74 grs.of ftrontian were depofited, and the fubfequentaddition of carbonated alkali threw down 132grs. more of carbonated ftrontian.STRONTIANITE . Stroatiamt , Worn.

Its colour is dear afparagus green, paffmgto greenilh or yellowifti white, or apple green.It occurs in mafs, the rifts or cavities of w’hichare often lined with bundles of acicular cryftalsthe form of which approaches to the four orfix-fided prifm. Its longitudinal fra&ure isnarrow, ftrait, and divergingly radiated, with •a Alining pearly luftre: the crofs fraftura isfine-grained uneven, paffmg to fplintery, andits luftre is only glimmering. Its fragments arewedge-fhaped or indeterminate. It occurs inthin fcapiform, and wedge-fhaped diftimT con-cretions. It is more or lefs tranflucent, fome- •

Trauf, for 175S, j>. J.'