SAN

SAN

( 2S5 )

SANDIVER, is the fcum and fediment ofthe large crucibles ufed in the making ofGlass , which fee.

SAND. Sand , Germ. Sable, Fr.

SANDSTONE . Sandjlein, Germ. Gres. Fr.

The effentsal component part of fandftone isquartz in rounded grains of various fizes, fromthe fmalleft that are vifible to the naked eye tothofe that are about the magnitude of a muf-tard feed. All fandftones are ftratified, but infome beds there alfo occur pretty regular fif-fures in two directions perpendicular to theftratification, thus dividing the ftone into pa-rallelopipedal maffes. When dilintegrated itforms Sand .

There are feveral diftin£t formations offandftone, but mineralogifts are by no meansas yet agreed with rcfpeCt to their number; thefour following, however, are made out withtolerable accuracy.

1. Primitive calcareous fandftone.

Its colour is for the moft part greyifh orgreenifh grey. It occurs in mafs. Its fraCtureis fplintery ; its fragments are blunt-edged; itis tranflucent at the edges, is moderately hard,giving a few fparks when ftruck againft thefteel. It effervefces with acids, and when itscalcareous cement is diffolved out, there re-mains a very friable mafs of fine white fand.It does not appear to contain any extraneousminerals. It refts upon gneifs and large-grainedgranite.

2 . Ferruginous fandftone.

The colour of this is for the moft partochery red or rcddifh brown, fometimes thoughrarely it is yellowifti white. Its frafture isvery coarfe fplintery; it is opake and foft, be-ing reduced to fand by a moderate blow. Itfeldom effervefces with acids, its cement beingalmoft always iron ochre with a little clay. Itreadily difintegrates by expofure to the wea-ther. It contains not unfrequently extraneousminerals, fuch as reddle in fniall fragments, vi-treous copper and other ores of this metal, andvery rarely galena, alfo petrified wood. InThuringia it is covered with bituminous mar-ine.

3 - Gritftone.

Of this there are two varieties, the compactand fchiftofe.

The former is of a .greyifh white colour,iometimes fpotted or ftriped with ochre yel-low. Its fraQure is coarfe fplintery. It veryrarely effervefces with acids. It is harder thanthe preceding and gives lively fparks when

‘ An. Cliim.

ftruck againft the fteel. It is not readily de-compofed by expofure to the air.

The fchiftofe grit differs from the precedingin its fra£lure w-hich is coarfe flaty, and inbeing more eafily pulverizable. It is fome-times intimately mixed with clay and thenforms the common flag-forte, in which ftate itscrofs fracture is earthy, and it contains im-preffions of fhells.

Gritftone generally occurs in the indepen-dent coal-formation, and contains few extraneousminerals except mica which is particularlyabundant in the fchiftofe variety. The elafticquartz or flexible fandftone of South America ,appears only to be a kind of fchiftofe grit.

4 . Soft calcareous fandftone. Molaffe, Fr.

The ufual colour of this is light greyifh oryellowifh. Its fra£ture is coarfe fplintery, paff-ing into granular. It is foft, and when in thequarry is almoft friable, but hardens by expofureto the air. Its cement is calcareous.

It occurs alternating with oolite and the othermoft recent varieties of limeftonc.

The ufes of fandftone are very confiderable.It is the ftone moft commonly employed inarchitecture; the fchiftofe varieties are ufed asflag-ftones, and for covering houles, for whichlaft purpofe however they are inferior to flatejthe harder kinds of gritftone are made intogrindftones, and on account of their infufibilityare employed for lining furnaces, &c.

SAP, The fap of trees is a watery mucila-ginous liquid, often ftrongly faccharme, fo aseven to yield a large quantity of fugar, and tofurnifh a very ftrong fermented liquor, andcontaining feveral other faline fubftances. Itappears to vary confiderably in its compofition,and to fall very far fhort of the uniformitywhich diftinguifhes the common juice of ani-mals.

The mode of extra£ling Sugar from the fapof the maple, will be mentioned under thatarticle.

Vauquelin has made an ufeful though in-compleat analyfis of the fap of feveral of thecommon trees, chiefly with a view to the falineand earthy contents, and has difeovered theprefence of acetite of potafh in all of them,which entitles the acetous acid to be rankedamong the native acids as well as being a pro-duct of fermentation.

The following is a fhort abftradt of Vauque-lin’s experiments. a

Sap of the Elm. This juice, which was col-tom, xxxi,