■s P E

S P I

( 536 )

-the furface, and partly fink to the bottom, andare thus got rid of; the fluid, in appearance aperfectly pellucid oil, is now allowed to cool,and forms on congealing a mafs of purifiedfpermaceti.

The colour of fpermaceti is a pure brilliant; almoft filvery white; it is compofed of femi-.tranfparent cryftalline plates ; is fofter andmore brittle than white wax, has very littleflavour, and only a flight tallowy odour. Itsfuperior tranfparency, high luft're, and cryftal-line texture, at once diftinguilh it from everyother fpecies of concrete oil. Its point of con-gelation is ii2°Fahr. 13 y the afliftance of awick it burns with a clear white .flame, fuperiorto that of tallow, and without any difagreeableodour, hence its excellence as a material for.candles.

Spermaceti by diftillation at a gentle heat,pafles over in the ftate of a fluid oil, which■concretes on cooling, a very flight carbonace-ous refidue being left in the retort; by re-peated diftillation, however, the fpermaceti be-comes permanently fluid at the common tem-perature. It requires according to Thouvenel,a much lefs heat for it's volatilization than moftof the other oils do, and therefore is lefs de-compofed by the procefs ; in particular no acidmakes its appearance. But according to theexperiments of Crell a greater heat is requiredfor its diftillation than for that of fat, the coagu-lated oil, thus procured, is partly white andpartly brownilh; by repeated diftillation it af-fords a yellowifh acid, becomes more fluid, butftill coagulates in the cold. The acid whenrectified by diftillation is entirely colourlefs,and affords the fame falts with earths and alka-lies as Crell’s febacic acid. The oil unites withammonia into a faponaceous emulfion.

Spermaceti is foluble in boiling alcohol,though very fparingly, 170 parts of the men-Itruum being required for this purpofe, andthe whole of the fpermaceti appears to be againprecipitated as the folution cools. a Warmether .diflblves it very, copioufly, but feems toretain none of it when cold. Oil of turpentinekas the fame effeft. With cauftic potafli itcombines into a foap, foluble in warm water.Fluid ammonia when cold has no aft ion onfpermaceti, but when warm diflblves it withgreat facility, forming an emulfion which is notdecompofed either by Ample cooling, or bymixture with water; the addition of an acidhowever inftantly precipitates the fpermaceti.With concentrated fulphuric acid it forms a

browruflt folution, which when dropped intowater gives up its fpermaceti apparently unal-tered. It diflblves fulphur as the other fat oilsdo. By long expofure to the air it acquires ayellow tinge and becomes rancid.

The great ufe of fpermaceti is for makingcandles; it is alfo employed in medicine.

SPINELL, or true Ruby. Spinel!, Wern.Spindle , Hauy and Broch.

Its colour is red mixed with various tints ofblue or yellow; hence it occurs carmine, hya-cinth, cochineal, and cherry red, rofe red,"andrarely blood red, alfo violet blue, bluifh green,and orange yellow. It occurs in grains, inEmail rounded fragments, and cryftallized.

The primitive form of its cryftals is the re-gular oftohedron, befides which it exhibits the.following varieties.

1. The cuneiform oftohedron.

2. The primitive oftohedron with the edgesof the common bafe truncated.

3. The fame with all the edges truncated.

4. The primitive oftohedron divided obli-quely into two fegments which are turned oneach other £ of a circle, thus forming a foiidwith alternate faliant and re-entering angles.

The cryftals are fmall and very fmall, rarelymiddle-fized. The faces of the oftohedron arefmooth, the planes of the truncatures are lon-gitudinally ftriated. Its luftre both extern,illyand internally is brightly ftiining, vitreous. Itscrofs frafture is conchoidal, its longitudinalfrafture is lamellar in three directions. It va-ries from tranflucent to tranfparent Its hard-nefs is very confiderable, though inferior tothat of fapphire. Sp. gr. 3.57—3.64.

It is infufible before the blowpipe withoutaddition, but it melts with borax and acquiresa green colour. When ground to a very finepowder, it is foluble by long digeftion in boil-ing fulphuric acid. It was firlt analyl'ed byKlaproth , and afterwards by Vauquelin, withthe following rei'ults.

Klapr.

Vauq.

Alumine

74-5

— 82.47

15.5

— 0.

Silex

8.25

— 8.78

Magnefia

r-5

— 0.

Oxyd of iron

o -7 5

— 0.

Lime

0.

— 6.18

Chromic acid

Its geological fituation is not known; it oc-curs however imbedded in calcareous fpar and

■ Bollock in Nich. Journ. 8vo. iv. p. 34.