342 G H £ M 
and even deftroying the extractive mucous fub fiance with 
which it-is vitiated at firft. Starch, chemically confi¬ 
dered, is a mucilage of a peculiar nature. This mucilage, 
which has been improperly confidered as an earth by 
fome chemilts, differs greatly from the glutinous part. 
It burns without emitting an empyreumatic fmell. By 
dillillation with a naked fire, it affords an acid phlegm, 
of a brown colour, and a very thick empyreumatic oil 
towards the end. Its coal is eafily reduced to allies, 
which contain fixed alkali. By dillillation, it gives the 
fame products as gUm and fugar. 
Starch is not foluble in cold water, but when boiled 
in water, it forms a kind of glue, called fiarch by the 
.laundreffes, and ufed, with a mixture of blue, for ftiffen- 
ing linen. This llarch, when dried, prefents a folid 
tranfparent mafs, fimilar to gum in fome refpefts, but 
dilfering from it by not being foluble in cold water. 
Starch, when heated with fix times its weight of nitric 
acid, the acid becomes decompofed, and the ltarch paffes 
to the ftate of oxalic acid. Chaptal remarks, that if di¬ 
luted nitric acid be digelled on ltarch, the acid is decom¬ 
pofed, and the ltarch paffes to a Hate refembling that of 
the ligneous fibre. Jamiefon of Leith, in a paper which 
he read to the medical fociety of that place, gave an ac¬ 
count of fome very fingular refults which he obtained, 
by digelting ltarch in muriatic acid. This acid, which 
concentrated and colourlefs, diffolved ltarch in a tempe¬ 
rature equal to 90 0 of Fahrenheit. By increafmg the tem¬ 
perature, the folution acquired a browniff colour, and 
at length a brownilh black precipitate was formed, which 
leemed to poffels all the properties of charcoal. On add¬ 
ing cauftic foda to the liquor, and fubjeCting it to eva¬ 
poration, a linall quantity of acetit of foda was obtained. 
By diltilling the muriatic acid from llarch, a carbonace¬ 
ous refidue was obtained, which inflamed readily with 
nitric acid, and which in fome cafes was fo inflammable, 
as to take fire by Ample expofure to the air. 
Of Gluten. —The glutinous part, is a tenacious, 
duftile, elaltic, matter, of awhitilh grey colour. When 
drawn out, it extends about twenty times its length be¬ 
fore it breaks, and appears as if compoled of fibres, or 
filaments, placed befide each other, according to the di¬ 
rection in which it has been drawn. If the force ceafes, 
.it relumes its original form by its elafticity. By drawing 
it out, in different directions, it may be made fo thin, 
.that its polifhed furface refembles the texture of animal 
membranes. In this Hate it adheres Itrongly to dry bo¬ 
dies, and forms a very tenacious glue, which was ufed 
by fome perfons to join broken china, long before che- 
.milts found the means of obtaining it in large quantities. 
Beccari has obferved, that the proportion of glutinous 
matter is from a fifth, to a third, and more, in flour of 
the belt quality; he has likewife obferved, that this 
.quantity varies in different feafons, and according to the 
jaature of the corn. 
The fmell of the glutinous matter is faint, and refem¬ 
bles that of mucilage ; expofed to a fire capable of fud- 
,-denly drying it, it lwells up prodigioully. In a dry air, 
or mild heat, it dries very well. It is then femi-tranf- 
parent, and hard, like glue, and fnaps fhort like that 
fubltance, its elallicity being gone. If in this Hate it be 
placed on burning coals, or applied to the flame of a 
candle, it exhibits all the characters of an animal fub- 
Itance ; it decrepitates, fwells, liquefies, curls up, and 
burns like a feather, or a piece of horn, emitting, at the 
fame time, a Itrong and fetid fmell. By dillillation, it 
affords, like animal fubltances, water, impregnated with 
ammoniac, ammoniacal carbonat, and an empyreumatic 
oil. Its coal is very difficultly incinerated, and dees not 
contain fixed alkali. 
Frelh gluten, expoled to a hot and moift air, becomes 
changed, and putrifies abfoluteiy in the fame manner as 
animal fubltances. When it retains a linall quantity of 
ltarch, this lait palling to the acid fermentation retards 
S T R Y. 
and modifies the putrid fermentation, and converts the 
fubltanceint.oaftatenearly fimilarto thatofeheefe. Rouelle 
theyoungerprepared acheefe with thegluten, which fingu- 
larly refembled in its fmell and fade, that of Gruyere, 
or of Holland. Water does not at all diflblve this gluti- 
nous matter. By boiling in this fluid it becomes folid, 
lofes its extenfibility and adhefive quality, but does not 
acquire either tafte or lolubility in the faliva. Neverthe- 
lefs, we mult obferve, that the gluten owes its elallicitjc 
and folidity to the water which formed the palle. In fa ft, 
this vegeto-animal portion, though capable of becoming 
folid and elaltic, is pulverulent,' and,without cohefion in 
the flour; but, as foon as water is added, its particles 
abforb the fluid, and adhere together, forming the elaltic 
fubltance called gluten. Water, therefore, contributes 
greatly to the formation of this fubltance, and it may 
perhaps be confidered as a compound, faturated with, 
and incapable of ablbrbing a larger quantity of water. 
This is fo true, that it ablbluteiy lofes its adhelion and 
elaltic properties by drying. 
Moll faline fubltances act more or lei’s efficacioully on 
the gluten. The caultic fixed alkalis in the fluid Hate 
dilfolve it by boiling. This folution is turbid, and de- 
pofits, by the addition of acids, a gluten which is not 
elaltic. The mineral acids diflblve the gluten. The 
nitric acid diflblves ft with great aCiivity, and Berthollet 
has.obferved, that this acid dilengages the azotic gas, as 
it does from animal fubltances. When this elaltic fluid has 
been emitted, the folution affords a large quantity of ni¬ 
trous gas, and becomes of a yellow colour. By evapo¬ 
ration it affords cryftals of the oxalic acid. The fulphu- 
ric and muriatic acids form brown or violet l’olutions of 
this fubltance, from which a kind of oily matter feparates; 
thegluten being truly decompofed. Poulletier, who has 
made many experiments on this fubltance, has aifeovered, 
that ammoniacal lalts may be obtained from thefe com¬ 
binations, diffoived in water, or fpirit of wine, and eva¬ 
porated in the open air. Vauquelin and Alexander 
Brongniart found that gluten triturated in acetous acid 
diffolved with great facility. This folution is not tranf¬ 
parent ; it may be kept a long time. By How evaporation 
and adding a few drops of alkali, the gluten is revived 
with all its properties. Here then we have a good method 
of preferving gluten unchanged. 
Other experiments have fliewn, 1. That the alhes of 
flour contain eighty-four grains of calcareous phofphat 
in the pound ; fo that a perfon who eats a pound of 
flour a-day, will take in little more than three pounds fix 
ounces of calcareous phofphat in the year. 2. That the 
flour of wheat gives no carbonat of lime by incineration, 
while the ftraw furnillies a coufiderable quantity, with 
fcarcely any fenfible appearance of phofphat of lime. 
The Vegetable Albumen. —Fourcroy, obferving that a 
matter coagulable by heat was feparated from juice of 
cochlearia, crefles, See. along with the colouring matter, 
took two pounds of the juice of the young crefles, and 
filtered it in the cold. The coarfer part of the fecula was 
feparated in this way. The liquor was of a clear green 
colour. ’Expofed to the air in a flat veffel, in two hours 
the liquor became muddy, and a finer green fecula than 
the firft was dilengaged, which was feparated by filtering 
it. The ley was now of a pale green colour. When 
poured in boiling water, a coagulation took place of a 
great number of fmall whit iff flocks ; fimilar flocks ap¬ 
peared in another portion of this juice, which had been 
left expofed fo the atmolphere ; and fulphuric acid fepa¬ 
rated a fimilar matter from a third portion. The fub- 
Itance obtained in thefe three different ways, waffed in 
water, exhibited all the properties of annual albumen. 
It diffolved in alkalis, was rendered more folid by boiling 
water, gave a green tinge to blue vegetable colours, and 
afforded ammoniac in dillillation ; with moifture in a 
warm atmofphere, it exhaled a fetid ammoniacal fmell, 
and exhibited every fymptom of putrefa&ion. This 
enables 
