DEN 
diums. Hence, if the density of the air be 
sensibly altered, bodies equally heavy in a 
rarer air, if their specific gravities be consi- 
derably different, will lose their equilibrium 
in the denser, and the specifically heavier 
body will preponderate. See Pneuma- 
tics. 
Density of planets. The densities of bo- 
dies being proportional to their masses di- 
vided by their bulks ; and, when bodies are 
nearly spherical, their bulks are as the 
cubes of their semi-diameters, of course the 
densities in that case are as the masses di- 
vided by the cubes of the semi- diameters. 
For greater exactness, we must take that 
semi-diameter of a planet which corres- 
ponds to the parallel, the square of the sine 
of which is equal to r, and wliich is equal to 
the tliird of the sum of the radius of the 
pole, and twice the radius of the equator. 
This method gives us the densities of the 
principal planets as follows, that of tlie sun 
being unity: \ 
Earth 3.93933 
Jupiter 0.86014 
Saturn 0.49512 
Herschell 1.13757 
See Astronomy. Planets, masses of. 
DENTALIUM, tooth-shell, in natural 
history, a genus of the Vermes Testacea. 
Generic character : animal a terebella ; 
shell univalve, tubular, straight or slightly 
curved, with tlie cavity open at both ends, 
and undivided. There are 22 species, some 
of which are found in the fossil state ; for 
there are but few species in this country, 
and those principally of the minuter kind. 
D. imperforatum is found at Sandwich, but 
is not common. The shell is white, opaque, 
transversely striate, and as its specific name 
imports, imperforate. 
DENTARIA, in botany, English tooth- 
wort, a genus of the Tetradynamia Siliquo- 
sa class and order. Natural order of Sili- 
quosae. Cruciferae, Jussieu. Essential cha- 
racter : silique bursting elastically with the 
valves rolled back ; sterna emarginate ; ca- 
lyx converging lengthwise. There are four 
species, of which D. enneaphylla, nine- 
leaved toothwort, is about a foot and half 
in height; leaves bitemate; leaflets lan- 
ceolate, serrate, acuminate, and smooth; 
flowers from three peduncles forming a pa- 
nicle or raceme, erect, fasciled ; calyx pale- 
green or yellowish; petals reddish-yellow, 
or yellowish-red ; there is a gland oil each 
side, between the longer stamens and the 
calyx, and one surrounding the base of each 
DEP 
shorter stamen ; in each cell are four seeds. 
It is a native of Hungary, Austria, Idria, 
Friuli, Silesia, in the woods. It flowers in 
April and May. 
DENTELLA, in botany, a genus of the 
Perrtandria Monogynia class and order. 
Natural order of Contort*. Rubiaceae, Jus- 
sieu. Essential character : corolla tubular 
five-cleft, with three toothed segments ; ca- 
lyx five-parted ; stigmas two ; capsule glo- 
bular, inferior, two-celled, many-seeded. 
There is but one species, viz. D. repens, a 
native of New Caledonia. 
DENTIFRICE, a remedy for the teeth. 
Various are the compositions sold for the 
purpose of keeping the teeth in good pre- 
servation; they are mostly composed of 
earthy substances, finely powdered, and 
mixed with alum. Acids, though very ef- 
fectual for cleansing the teeth, are de- 
cidedly mischievous. Charcoal is at pre- 
sent in high reputation as a dentifrice ; but 
the sepia or cuttle fish, sold by the chemists 
and finely powdered, and which are picked 
up on the sands on the southern coast, are 
much valued for this purpose. 
DENTITION, the breeding or cutting 
the teeth in children. See Infancy, dis- 
eases of. 
DEOBSTRUENTS, in pharmacy, such 
medicines as open obstructions. 
DEODAND, in our customs, implies a 
thing devoted or consecrated to God, for 
the pacification of his wrath, in case of any 
misfortune, as a person’s coming to a vio- 
lent end, without the fault of any reason- 
able creature ; as if a horse should strike 
his keeper, and so kill him. In this case, 
the horse is to be deodand ; that is, he is to 
be sold, and the price distributed to the 
poor; as an expiation of that dreadful 
event. 
DEPARTURE, in navigation, is the 
easting or westing of a ship in respect of 
the meridian it departed or sailed from : or 
it is the difference of longitude, either east 
or west, between the present meridian the 
ship is under, and that where the last rec- 
koning or observation was made. This de- 
parture, any where but under the equator, 
must be accounted according to the number 
of miles in a degree, proper to the parallel 
the ship is under. 
DEPHLOGISTICATED, a term ap- 
plied by Dr. Priestley, to what is now called 
oxygen gas, when he first discovered it. It 
was called by Scheele, who discovered it at 
the same time, vital air. 
DEPOSITION. Proof in the high court 
