156 
ALLIUM CEPA. 
This species of Allium is the Kpofj^vov of Dioscorides, its specific 
appellation is derived frOm caput, a head, oa account of the form 
of its bulb ; the native country of this plant is not known, nor the 
precise period of its introduction into Europe, over most parts of 
which it has been long cultivated as an article of food. The 
botanical character of this plant is so well known as scarcely to 
require description. The bulb is globose, simple, formed of con- 
centric scales, with fibrous roots issuing from the base ; the stem is 
a naked swelling scape, rising to the height of two or three feet ; 
the leaves are fistular, spreading, pointed and shfeathing at the 
base.; the flowers are produced in a close head or capital, inclosed 
in a deciduous spathe ; it blossoms in June and July. Several 
varieties of the onion are cultivated in our gardens, but as they are 
never used medicinally we judge it quite unnecessary to enumerate 
them. 
• Sensible and Chemical Properties, &c. of Garlic, &c. 
Every part of this plant has an offensive and pungent odour, this 
odour is so powerfully diffusive and penetrating, that it impregnates 
the whole system on the root being taken into the stomach, ahd 
even when applied to the soles of the feet its odour may be perceived 
in the breath, perspiration and urine. To the taste the roots are 
pungent and acrimonious. These latter properties chiefly depend 
upon an essential oil, which may be obtained by distillation with 
water ; this oil is of a thick ropy consistence, of a yellowish colour, 
heavier than water, and possessing the active properties of the garlic 
in a concentrated degree ; when applied to the skin it produces great 
irritation and subsequently blisters ; it strikes a black colour when 
triturated with oxide of iron. The acrid principle may also be 
obtained by expression ; the expressed juice is of a thick consistence 
and slightly reddens the infusion of turnsol and other vegetable 
blues. Alcohol, water, and acetic acid also extract the acrid 
principle of garhc ; with the former menstrua a reddish yellow 
tincture is obtained, which leaves, when evaporated, a brown acrid 
extract, that imbibes moisture from the air. By simple coction 
with water, garlic is rendered mild and inert. On drying it loses 
nearly two thirds of its weight, without suffering any considerable 
loss of its taste or smell. 
The sensible and chemical properties of the common onion, as 
well as the leek, resembles those of the garlic, but in a less powerful 
degree ; their active qualities like the garlic depending upon an 
essential oil, a small quantity of which may be obtained by 
distillation. The distilled oil from the onion is combined with 
