STARCH. 
LINE, Arrow-Root, Cassava, Orcuis, Saco, Fa- 
| RInA, OATMEAL, and Potato. 
“Starch,” says Boussingault, “is contained in 
| the cells of vegetables under the form of small 
white granules which have no crystalline struc- 
ture. In the year 1716, Leuwenhoeck ascer- 
tained that these granules were globular bodies 
more or less regular in their contours. He be- 
lieved that he could perceive each globule en- 
closed in an envelope, a kind of sac, different in 
its nature from the matter which it contained. 
M. Raspail, a few years ago, confirmed by his 
own researches the observations of Leuwen- 
hoeck; he further attempted to measure the 
diameter of the globules in different kinds of 
starch, and came to the conclusion that their 
capsule is insoluble, and that it is the internal 
part alone which is soluble in hot water. Since 
then MM. Payen and Persoz have ascertained 
that if the globules of starch be really surrounded 
by a capsule, it must be present in a quantity 
scarcely appreciable,—a quantity not exceeding 
soooth of the weight of the starch. These first 
researches were followed by the subsequent ob- 
servations of M. Payen, who has devoted himself 
to the study of the amylaceous principle with a | 
zeal and perseverance which must secure him 
the gratitude of chemists and physiologists. M. 
Payen has examined a vast number of fecule mi- | 
croscopically; the largest granules he observed : 
were obtained from one of the varieties of potato, 
from the Menispermum paimatum, and the Canna 
gigantea. The globules of starch frequently ex- 
hibit a polyhedral appearance, a figure which 
evidently results from their mutual pressure as 
they have lain in the cells of the vegetable. 
Notwithstanding a great general analogy of 
form, the granuies of the starch of different spe- 
| cies of vegetables, still present peculiar physiog- 
nomies, so that they can be distinguished in 
many instances by the practised eye. A charac- 
| ter common to the majority of fecule, however, 
| is roundness of contour, when their particles 
have not been compressed by their contact in 
| contiguous cells. Microscopical and chemical 
| researches alike show that starch is homogene- 
| ous in properties, as in composition; that its 
| globules are composed of concentric layers, the 
external of which have exactly the same charac- 
; ters as the internai layers. 
; “In the natural state, starch is insoluble in 
| water and in alcohol; it is very ductile; and 
| under the influence of certain agents, it exhibits 
a great degree of contractility. Feculas retain 
water with considerable force; the quantity re- 
tained varies with the temperature at which 
the drying was accomplished. Thus the fecula 
of the potate, which is moist and porous, even 
when: subjected to strong pressure, still retains 
45 per cent. of water. This is the green or raw 
starch of manufacturers. Dry starch is very 
hygrometric. If after being dried it is placed in 
an atmosphere saturated with moisture, at 20° 
centig. (68° Fahr.) it will absorb nearly 36 per 
cent. of water, and its bulk increases in the ratio 
of one to one and a half; in this state starch is 
brilliantly white, and its grains adhere so closely 
that they form a mass of sufficient firmness to 
take the impress of a seal. Starch in this state, 
however, pressed upon paper yields no percepti- 
ble trace of moisture; it is too hard and adher- 
ent to pass through a sieve; and when thrown 
ona metal plate heated to 257° Fahr. its parti- 
cles immediately unite and form a cake. The 
starch of commerce, in the state in which it is 
usually found in shops, contains 18 per cent. of 
water ; it is either pulverulent or readily reduci- 
ble to powder, though by slight pressure in the | 
hand, it may be formed into a mass or ball. 
After drying in vacuo at the ordinary tempera- 
ture, starch retains no more than 10 per cent. of 
moisture ; a temperature not less than 284° Fahr. 
is required to dry it completely ; the water which 
it retains at this temperature belongs to its con- 
stitution, and cannot be taken from it except by 
combining it with bases. MM. Collin and Gaul- 
tier de Claubry discovered the important charac- 
ter of starch, that of yielding a fine blue or violet 
colour on combining with iodine. According to 
M. Payen, the colour is more intense, nearer to 
| blue and more lasting, in proportion as the starch | 
is more strongly compressed ; the effect of sepa- 
ration is to turn the blue to shades of violet 
which approach redness as the substance is | 
looser. The same fecula, according to the de- | 
gree of its aggregation in plants, is seen to as- | 
sume shades, which are first reddish, then violet, | 
and eventually of a more decided blue colour, 
under the action of iodine. M. Lassaigne has 
noticed a very curious property of the combina- 
tion of iodine and starch ; if an amylaceous fluid, 
having the decided blue colour, be heated to 193° 
or 194° Fahr., the solution becomes completely 
blanched ; but it resumes its former tint as the 
liquid cools. This property, which starch pos- 
sesses of striking a blue colour with iodine, ren- 
ders one of these bodies an excellent test for the 
other. However, as the iodine must exist in the 
free state to produce its effect, it is necessary, 
when the blue colour does not show itself at 
once, in a solution in which iodine is suspected, 
and to which starch has been added, to add a few 
drops of sulphuric acid, so as to decompose the 
hydricdic acid in cases where it may exist. 
“Tt is familiarly known that, if raw starch be | 
mixed with boiling water, the result will be a | 
thick, paste-made starch. According to M. Pay- | 
en, the change that takes place in the state of | 
the fecula is owing to a swelling, a rupture, or | 
disgregation of its granules. By heating a drachm 
of starch, mixed with about a couple of ounces of 
water to about 140° Fahr., the microscope shows 
us that the smallest or youngest grains,—those 
possessed of the least cohesion,—have absorbed a 
considerable quantity of water, and that the ex- 
pansion of the contents has caused a certain num- 
