105 
beurt tells us that it is a yellow^ mild, agreeable oil, and is much 
used for the table. Recently-drawn olive oil deposits by stand- 
ing, a white fibrous matter, which the ancients employed in med- 
icine under the name of amurca. In commerce we meet with 
several varieties of olive oil of unequal quality. A very fine 
kind (Florence oil) is brought from Florence in flasks, which 
are surrounded by a kind of net-work formed by the leaves of a 
monocotyledonous plant, and packed in what are called in com- 
merce half chests. Lucca oil is imported in jars, holding nine- 
teen gallons each. We have, besides, Gallipoli, Sicily, and 
Spanish oil : they are of inferior quality. According to Sieuve, 
100 lbs. of olives yield about 32 lbs. of oil ; 21 of which come 
from the pericarp, 4 from the seed, and 7 from the woody mat- 
ter of the nut. That obtained from the pericarp is of the finest 
quality. Olive oil is an unctuous fluid, of a yellow or greenish 
yellow colour, having little or no odour, and a mild taste. It is 
lighter than water ; readily dissolves in aether, but is very slightly 
soluble only in alcohol. With alkalies if forms soaps. The 
Castile soap employed in medicine is made with this oil and so- 
da: it is essentially a mixture of oleate and margarate of soda. 
Olive oil combines with the oxyde of lead to form the well known 
emplastrum plumbi or eleomargarate of lead. By exposure to 
air this oil readily becomes rancid. 
142 Adulteration of Olive Oil. Olive oil is said to be some- 
times adulterated with poppy oil, though I believe such an oc- 
currence to be rare in this country. Four methods, however, 
have been proposed for detecting the fraud ; and as they have 
reference to some characteristic properties of olive oil, they de- 
serve notice. The first is the beading : if we shake pure olive 
oil in a phial half filled with it, the surface of the oil soon becomes 
smooth by re|)ose ; whereas when poppy oil is present, a num- 
ber of air bubbles (or beads, as they are termed) remain. The 
second method is by congelation, — olive oil more readily con- 
gealing than poppy oil. The third method is that founded on 
the conducting power of the oil for electricity, and effected by 
an instrument called an electrical diagometer. This consists of 
one of Zamboni’s dry piles and a feebly magnetized needle mov- 
ing freely on a pivot. The electricity develoj)ed by the pile is 
made to produce a deviation in the direction of the needle; but 
when any substance is interposed between the needle and the 
153 ACCTARICM 
