SUG
( 351 ) SUL
Sard and brittle. It is void of fmell, and itstafte is that of pure fweetnefs. When hardloaf fugar is rubbed in the dark it is highlyluminous.
Sugar is very foluble both in water and al-cohol. The watery folution may be preiervedfor a length of time unaltered it the fugar ispure, but if it is mixed with mucilaginous,farinaceous, or other matters, it readily entersinto the vinous fermentation. In this procefsthe ftrength of the liquor and quantity ofalcohol produced, depend direftly on the quan-tity of fugar prefent, whence the mod effentialpart of the procefs of vinous fermentation isreafonably inferred to be the converfion of fugarinto alcohol. From comparing the produdlswith the materials of fermentation, Lavoilierconcluded that fugar was a triple compound of28 parts (by weight) of carbon, 8 parts ofhydrogen, and 64 parts of oxygen.
Sugar melts at a heat confiderably above thatof boiling water, and forms a blood-red vifcidfluid, which when cooled has a not ungratefulflavour of empyreuma mixed with the naturalfweetnefs. Wlren melted, it takes fire on ap-plying a lighted fubftance, and burns with aItrong red flame, and a peculiar and'very pene-trating odour which excites coughing, and isowing to the production of an acid.
If fugar is diftilled per fe from a glafs retortwith a heat gradually increafed to rednefs, andthe products carefully collected, they will befound to be, firft a coloured liquor ftronglyacid and pungent, which is called the Pyromu-cous , being the fame as is furnifhed by muci-lage under a fimilar treatment. A large quantityof gas comes over at the fame time, which ishydro-carbonat mixed with a little carbonicacid, and a very pure charcoal is left behind,which bums away in the open air withoutleaving any refidue J* Neither azot, ammonia,nor lime, or any other fubftance, is obtained inthis procefs; fo that fugar is one of the purefthydro-carbonous oxyds that we know.
Under the article Mucilage we have mention-ed in part the very interefting refearches on thecomparative nature of fugar and gum or muci-lage, carried on by the laft mentioned eminentchemift. It was there mentioned that fugar bybeing treated with phofphuret of lime (a difoxv-genatmg fubflance) loll its faccharine nature,and was converted into a clammy fubftance noiDii^r i°luble in alcoho], which ftrongly ■ rc-fembled mucilage. The converfe of this expe-riment however, (that is Of converting mucilage
* Cruikflwnk in Relic
into fugar by an oxygenating fubftance) won it!not anfwer, for when nitric and oxymuriaticacid were palled through a folution of gum-arabic in various ways, nothing faccharinecould be obferved, but the whole was convertedinto the oxalic and other acids.
The adtual chemical differencesbetween mu-cilage and fugar, as found by Mr. Cruiklhank,.are the following: fugar is foluble both in waterand alcohol, and cryftallizable from either folu-tion; but mucilage is infoluhle in alcohol, andrefutes to cryltallize from its watery folution.480 grs. of fugar yielded by diftillation i2ogrs.of charcoal, 270 grs. of liquid pyromucous acid,41 oz. meafures of carbonic acid gas, and 119oz. meafures of hydro-carbonat gas:—the famequantity of gum arabic yielded 96 grs. of char-coal, 210 grs. of pyromucous acid, 93 meafuresof carbonic acid, and 180 of hydro-carbonat.It alfo gave about 10 grs. of lime, and the acidwhen faturated with lime gave out a little am-monia, and hence lime and azot are fubftanccsthat belong to mucilage and not to fugar.
The habitudes of each fubftance with nitricacid alfo differ confiderably, as already mention-ed in part under the article Mucilage. Whengum-arabic (for example) is heated with nitrousacid only till nitrous gas begins to be diiengaged,a quantity of white infoluhle matter precipitateswhich is the Mucous acid, and the refidue ismalic acid which a further addition of thenitric converts into oxalic. But fugar is changedinto oxalic, or malic and oxalic acid, withoutthe produftion of any mucous acid. The quan-tity of oxalic acid produced from a given weightof fugar with nitric acid alfo exceeds thatyielded by the fame weight of mucilage'with 4the fame proportion of acid.
In the fpontaneous changes alfo fugar and'mucilage differ effential !y. Sugar being the 1
effential material of the vinous fermentation, butmucilage is incapable of this procefs when pure, .and appears'to contribute little to the generationof alcohol when in combination with fermenting •materials.
SUGAR, Acid of. See Oxalic Acid .
SUGAR, E'ntpyreionatic Acid of. See Sugar and .Pyromucous Acid.
SUGAR OF MILK. See Milk.
iAJ'LVUAV.y Ihimfo/ie. Sotfre, Fr. Schiuefely .Gernr.
Sulphur is found both in the mineral, vege-table, and animal kingdoms, in the two latterhowever it occurs fo rarely that all the vale-'i’8 EfTay en Platens.