EFF 
Ruddiman, &c. are likewise famous edi- 
tors. 
EDULCORATION, in chemistry, a 
term applied to the process of washing out 
from a precipitate any excess of acid or al- 
kali, or compound salt, that may adhere to 
it. The usual method is by filtration, re- 
peated with different watets, till the last 
portions that drain are wholly tasteless, and 
produce no change on the usual tests. This 
method is tedious, and often ineffectual, 
and the following adopted in its stead. 
When the precipitate, is deposited, instead 
of throwing it on a filter, pour it into a sil- 
ver crucible, and boil it with water ; after 
this, withdraw it from the fire, allow it a 
a few minutes to subside, and draw off the 
clear liquor ; then add fresh water to the 
residue, and boil it again, and proceed thus 
till all the soluble impurities are got rid of. 
EEL. See Mur.9ENA. 
Eel spear, a forked instrument with three 
or four jagged teeth, used for catching of 
eels ; that with the four teeth is best, which 
they strike into the mud at the bottom of 
tlie river, and if it strike against any eels, 
it never fails to bring them up. 
EFFECTS, in commerce, law, &c. the 
goods possessed by any person, whether 
moveable or immoveable. 
EFFERVESCENCE, in chemistry, is a 
rapid disengagement of gas taking place 
within a liquid ; in consequence of this, nu- 
merous bubbles rise to the surface, forming 
a head of froth, and bursting with a hissing 
noise. There is some resemblance between 
effervescence and fermentation ; the latter is, 
however, slower and more durable. Hence 
chemists formerly applied the term fermenta- 
tion to all the phenomena which are at pre- 
sent denoted by effervescence. Gas pro- 
duced by effervescence is by means of single 
or double elective affinity: in the one case it 
is generally carbonic acid gas, in the other 
it is either nitrous gas or hydrogen. Gas 
can have but little affinity with the fluid in 
wluch it is immersed, in order to produce 
effervescence. Thus, carbonic and muri- 
atic acids are both gasses, and are both ex- 
tricated from alkaline combinations by sul- 
phuric acid, yet a solution of carbonate of 
potash in water will produce a vehement 
effervescence with sulphuric acid, while mu- 
riate of potash in the same circumstances 
will occasion none at all, the carbonic acid 
having a very slight affinity for water acidu- 
lated by sulphuric acid, while the muriatic 
acid will combine with the same very readily. 
EFFLORESCENCE, in chemistry, is 
EGG 
the formation of a powdery crust, or of 
minute crystals, on the surface of any sub- 
stance. This term is applied to tw'o db- 
linct phenomena. Salts are either unalter- 
able in the air, or they attract moisture 
from it and are resolved into a fluid, or 
they yield part of their water of crystalliza- 
tion to the air, and are reduced to powder. 
This effect, at its commencement, is called 
efflorescence, and such salts are denominat- 
ed efflorescent. There is, however, an- 
other kind of efflorescence, which is dis- 
cernible in iron pyrites, or new mortar ; 
and in these cases it implies the appearance 
of-a surperficial covering of minute hair-like 
crystals, and is occasioned by the chemical 
changes that take place on the surface of 
the substance where these crystals appear. 
Thus sulphuret of iron is changed by efflo- 
rescence into sulphate of iron or green 
vitriol ; but sulphate of soda, when subjected 
to the efflorescence first mentioned, though 
changed in form remains the same in com- 
position, except that it has lost part of its 
water. The one destroys crystals, the 
other produces them. See Aikin’s “ Mine- 
ralogical and Chemical Dictionary.” 
EFFLUVIUM, in physiology, a term 
much used by philosophers and physicians, 
to express the minute particles which ex- 
hale from most, if not all, terrestrial bodies 
in form of insensible vapours. Sometimes, 
indeed, these effluvia become visible, and 
are seen ascending in form of smoke ; con- 
stituting what, in animals and plants, makes 
the matter of perspiration. 
Nothing can exceed the subtility of the 
odoriferous effluvia of plants and other 
bodies. Mr. Boyle tells us, that having ex- 
posed to the open air a certain quantity of 
asafoetida, he found its weight diminished 
only the eighth part of a grain in six days : 
hence, if we suppose, that during all that 
time a man could smell the asafoetida at 
the distance of five feet, it will appear that 
its effluvia cannot exceed the 
part of an inch m magnitude. 
The effluvia of mineral substances are 
called steams ; and when collected in 
mines, or other close places, damps. See 
Gas. 
Malignant effluvia are assigned by physi- 
cians, as the cause of the plague, and other 
contagious diseases; as the jail-distemper, 
hospital-fever, and the like. 
EFT. See Lacerta. 
EGGS. The eggs of hens and of birds, in 
general, are composed of several distinct sub- 
stances. 1. The shell, or external coating, 
