diffusiometer 
experiment, with the lower end plunged in mercury and 
the upper end closed with a porous plug ; the rate of dif- 
fusion is determined from the rapidity with which the 
mercury rises in the tube as the diffusion of the gas goes 
on through the porous plug. 
diffusion (di-fu'zhon), ii. [= F. diffusion = Pr. 
diffusio = Sp. difusion = Pg. diffusao = It. dif- 
ing, or the state or being diffused. () The grad- 
ual and spontaneous molecular mixing of two fluids which 
are placed in contact one with the other. It takes place 
without the application of external force and even when 
opposed by the action of gravity. It is explained by the 
motion and mutual attraction of the molecules of the two 
fluids. Diffusion is most rapid and marked between gases, 
but is also an important phenomenon of liquids. See diffu- 
sion of gases and diffusion of liquids, below. 
The process of diffusion is one which is continually 
performing an important part in the atmosphere around 
us. Respiration itself, but for the process of diffusion, 
would fail in its appointed end. 
W. A. Miller, Elem. of Chem., I. iii. 3. 
(6) A scattering, dispersion, or dissemination, as of dust 
or seed, or of animals or plants. 
The process of diffusion would often be very slow, de- 
pending on climatal and geographical changes, on strange 
accidents, and on the gradual acclimatization of new spe- 
cies to the various climates through which they might 
have to pass. Darwin, Origin of Species, p. 305. 
(c) Propagation or spread, as of knowledge or doctrine. 
Another measure of culture is the diffusion of know- 
ledge. Emerson, Civilization, p. 21. 
To our mediseval forefathers the great diffusion of the 
arts of reading and writing which followed on the inven- 
tion of printing was a boon beyond all words. 
E. A. Freeman, Amer. Lects., p. 242. 
((it) Diffuseness ; prolixity. 
To abregge 
Diffitsioun of speche. Chaucer, Troilus, iii. 296. 
Diffusion apparatus, an apparatus sometimes employed 
for extracting the sugar from cane or beet-root by dissolv- 
ing it out with water. Diffusion circles, luminous cir- 
cles, as those thrown upon a screen by a lens when the 
object is either too near or too far to be in exact focus. 
Diffusion of electricity and magnetism, propaga- 
tion analogous to the conduction of heat. 
This diffusion and decay of the induction-current is a 
phenomenon precisely analogous to the diffusion of heat 
from a part of the medium initially hotter or colder than 
the rest. Clerk Maxwell. 
Diffusion Of force, the phenomena of viscosity in mov- 
ing fluids. Diffusion Of gases, the diffusion through 
each other which takes place when two bodies of gas are 
placed in contact^ as when a bell-jar of hydrogen is placed 
base to base over one containing oxygen. After a certain 
time a homogeneous mixture is obtained, even if the heavier 
gas is placed below. When separated by a porous dia- 
phragm the relative rate of diffusion can be measured (see 
diffusiometer)', it is found to be the more rapid with the 
lighter gas. Diffusion Of heat, (a) A phrase employed 
to express the modes by which the equilibrium of heat is 
effected, viz., byconduction, radiation.andconvection. The 
term is also used, like diffusion of light (see light), to de- 
scribe the irregular reflection or scattering of the incident 
heat (and light) from the surface of a body not perfectly 
smooth, (b) Conduction of heat. Diffusion of liquids, 
the diffusion through each other which occurs when two 
liquids that are capable of mixing, such as alcohol and wa- 
ter, are placed in contact, even in spite of the action of grav- 
ity. It is closely related to the phenomena of exosmosis 
and endosmosis (which see), which take place when the li- 
quidsare separated by a porous diaphragm. See also dialy- 
sis. Diffusion of taxes, the theory that the community 
as a whole must bear the burden of any tax. no matter 
upon what commodity or persons it is originally levied. 
This theory rests on the assumption of perfect competition. 
Diffusion tube, an instrument for determining the rate 
of diffusion for different gases. =SyTL Spread, circulation, 
expansion, dissemination, distribution, 
diffusion-osmose (di-fu'zhon-oz"m6s), n. Os- 
mose due to the diffusibility of the liquids, and 
not to the chemical action of the membrane. 
diffusion-volume (di-fu'zhon-vol"um), re. The 
volume of a fluid which diffuses into a second 
in the same time that a given volume of the 
second diffuses into the first. 
diffusive (di-fu'siv), a. [= F. diffusif = Sp. 
difusivo = Pg. It. diffusive, < L. as if *dlffusivus, 
< diffusus, pp. of diffundere, diffuse: see dif- 
fuse.'] 1. Having the quality of diffusing or 
spreading by flowing, as fluids, or of dispers- 
ing, as minute particles : as, water, air, light, 
dust, smoke, and odors are diffusive substances. 
All liquid bodies are diffusive. 
T. Burnet, Theory of the Earth. 
Diffusive Cold does the whole Earth invade, 
Like a Disease, through all its Veins 'tis spread. 
Congreve, Imit. of Horace, I. ix. 2. 
2. Extending in all directions; widely reach- 
ing ; extensive : as, diffusive charity or benev- 
olence. 
No fear that the religious opinions he holds sacred, . . . 
or the politics he cultivates, . . . will keep back any from 
his share of the diffusive good. 
11. Choate, Addresses, p. 203. 
He [Hartley Coleridge] thinks intellect is now of a more 
diffusive character than some fifty years since, for progres- 
sive it can not be. Caroline Fox, Journal, p. 21. 
1612 
I seem in star and flower 
To feel thee some di/usiee power. 
Tennyson, In Mcniorlam, cxxx. 
diffusively (di-fu'siv-li), adv. Widely ; exten- 
sively ; iu every direction. 
diffusiveness (di-fu'siv-nes), re. 1. The state or 
character of being diffusive : as, the diffusive- 
ness ; copiousness of words or expression. 
Of a beautiful and magnificent diffusiveness Cicero is, 
beyond doubt, the most illustrious example. 
Blair, Rhetoric, xviii. 
diffusivity (dif-u-siv'i-ti)j n. [< diffusive + -ity.] 
The power or rate of diffusion. [Rare.] 
The diffusivity of one substance in another is the num- 
ber of units of the substance which pass in unit of time 
through unit of surface. Tait, Properties of Matter, p. 267. 
diffusqr (di-fu'zor), n. See diffuser. 
dig (dig), v.-. pret. and pp. dug or digged, ppr. 
digging. [< ME. diggen, dyggen (once deggen, 
for a rime) (pret. diggede, digged, pp. digged), 
prob. altered (through Dan. influence?) from 
earlier dikien, usually diken or assibilated di- 
cnen, dig, < AS. dician, make a ditch (= Dan. 
dige, raise a dike, = Sw. dika, ditch, dig ditches), 
< die, a ditch, etc. : see dike, ditch, v. and n. 
The pret. dug, for earlier digged, like stuck for 
sticked, is modern.] I. intrans. 1. To make a 
ditch or other excavation ; turn up or throw out 
earth or other material, as in making a ditch 
or channel or in tilling : as, to dig in the field ; 
to dig to the bottom of something. 
Thei wente to the tresour, aa Merlin hem taught, in the 
foreste, and lete digge in the erthe and fonde the tresour 
that neuer er [before] was seyn, and toke it oute of the 
erthe. Merlin (E. E. T. S.), ii. 370. 
I cannot dig ; to beg I am ashamed. Luke xvi. 3. 
The scripture says, Adam digged ; Could he dig without 
arms? Shak., Hamlet, v. 1. 
2. To study hard; give much time to study; 
grind. [Students' slang, U. S.] 
Here the sunken eye and sallow countenance bespoke 
the man who dug sixteen hours per diem. 
Harvard Itegister, 1827-28, p. 303. 
To dig out, to decamp or abscond suddenly : as, the de- 
faulter stole a horse, and dug out. [Slang, U. S.] 
II. trans. 1 . To excavate ; make a passage 
through or into, or remove, by loosening and 
taking away material : usually followed by an 
adverb : as, to dig up the ground ; to dig out a 
choked tunnel. 
Who digs hills because they do aspire, 
Throws down one mountain to cast up a higher. 
Shak., Pericles, i. 4. 
2. To form by excavation ; make by digging : 
as, to dig a tunnel, a well, a mine, etc. ; to dig 
one's way out. 
Whoso diggeth a pit shall fall therein. Prov. xxvi. 27. 
I believe more Men do dig their Graves with their Teeth 
than with the Tankard. HouieU, Letters, ii. 3. 
3. To break up and turn over piecemeal, as a 
portion of ground : as, to dig a garden with a 
spade ; a hog digs the ground with his snout. 
Dikeres and delueres digged [var. dikeden (A), vii. 100] 
vp the balkes. Piers Plowman (B), vi. 109. 
4. To excavate a passage or tunnel for; make 
a way of escape for by digging: as, he dug 
himself out of prison. 
Look you, th' athversary ... is digged himself four 
yards under the countermines. Shak., Hen. V., iii. 2. 
5. To obtain or remove by excavation ; figura- 
tively, to find or discover by effort or search ; 
get by close attention or investigation : often 
followed by up or out: as, to dig potatoes; to 
dig or dig out ore; to dig up old records ; to dig 
out a, lesson. 
There let Julianus Apostata dyggen him [John the Bap- 
tist] up, and let brennen [burn] his Bones. 
Mandeville, Travels, p. 107. 
As appeareth by the coynes of the Tyrians and Sidoni- 
ans, which are digged out and found daily. 
Purchas, Pilgrimage, p. 46. 
6. To cause to penetrate ; thrust or force in : 
followed by into : as, he dug his spurs into his 
horse's flanks ; he dug his heel into the ground. 
To dig down, to undermine and cause to fall by dig- 
ging. 
In their sclfwill they digged down a wall. Gen. xlix. 6. 
To dig in, to cover or incorporate by digging : as, to dig 
in manure. To dig over, to examine or search by dig- 
ging : as, he dug over the spot very carefully, but found 
nothing. 
dig (dig), re. [<<%,.] 1. A thrust; a punch; 
a poke : as, a dig in the ribs : often used figur- 
atively of sarcasm and criticism. 2. A dili- 
gent or plodding student. [Students' slang, 
U. S.] 
The many honest digs who had in this room consumed 
the midnight oil. Collegian, p. 231. 
digenesis 
digallic (di-gal'ik), a. [< di-% + gallic^ Used 
only in the following phrase Digallic acid. Same 
as taniiic acid (which see, under taimic). 
digamist (dig'a-mist), n. [< digamy + -ist.'} 
One who has been married twice ; a widower or 
widow who marries a second time. See biga- 
mist. [Rare.] 
Digamists, according to Origen, are saved in the name of 
Christ, but are by no means crowned by him. 
Lecky, Europ. Morals, II. 346. 
digamma (di-gam'a), n. [< L. digamma, also di- 
guiiiiitoii, digumi<i8, < Gr. diyafifia, also Aijau/iov, 
diyauiiot;, the digamma, a name first found in the 
grammarians of the first century (so called be- 
cause its form, F, resembles two gammas, T, set 
one above the other) ; < Si-, two-, twice, + yafi- 
fia, gamma.] A letter corresponding in deriva- 
tion and alphabetic place to the Latin and mod- 
ern European F, once belonging to the Greek 
alphabet, and retained longest among the .^0- 
lians. It was a consonant, and appears to have had the 
force of the English w. It went out of use with the dis- 
appearance of the sound signified by it from Greek pro- 
nunciation, but is restorable on metrical and other evi- 
dence in many ancient Greek words, especially in Homer. 
digammated (di-gam'a-ted), a. [< digamma 
+ -ate 2 + -erf 2 .] 1. Formed or spelled with a 
digamma; using a digamma. 
It is more than forty years since Richard Payne Knight 
published in 1820 his famous digammated Iliad or rather 
Vilviad of Homer. J. Hadley, Essays, p. 56. 
To the digammated and older form of the Greek ob- 
lique cases there corresponds also the Latin Jovem, Jovis, 
Jovi. Grimm, Teut. Mythol. (trans.), I. 193. 
2. Formed as if with a digamma : as, the digam- 
mated cross, a phallic symbol. 
digamous (dig'a-mus), a. [< LL. digamus, < Gr. 
6i\a/tof, married a second time, < Si-, two-, + 
yauos, marriage.] 1. Relating to digamy, or a 
second marriage. 2. In lot., same as androgy- 
nous. [Rare.] 
digamy (dig'a-mi), n. [< Gr. as if *diya/iia, < 
tuya/iof : see digamous.] Second marriage ; 
marriage after the death of the first spouse. 
[Rare.] 
Digamy, or second marriage, is described by Athanago- 
ras as "a decent adultery." Lecky, Europ. Morals, II. 346. 
digastric (di-gas'trik), a. and n. [= F. digas- 
trique = Pg. It. digastrico, < NL. digastrieus, < 
Gr. <!(-, two-, + yaoTr/p, belly.] I. a. In mini, : 
(a) Having two fleshy bellies with an interven- 
ing tendinous part, as a muscle : as, the omo 
hyoid, the biventer cervicis, etc., are digastric 
muscles. (6) Pertaining to the digastric Di- 
gastric fossa, (a) A shallow depression on the inner 
surface of the inferior border of the lower jaw, on either 
side of the symphysis. (6) The digastric groove. Digas- 
tric groove, the depression on the inner side of the mas- 
toid process of the temporal bone. Digastric lobe of 
the cerebellum. See cerebellum. Digastric muscle. 
See muscle. Digastric nerve, a branch of the facial 
nerve, supplying the posterior belly of the digastric 
muscle. 
II. H. Amuscleof thelowerjaw: socalled be- 
cause in man it has two bellies. In its general- 
ized condition it is a principal depressor of the lower jaw, 
opening the mouth and antagonizing the temporal and 
masseteric muscles. It arises from the back part of the 
skull, and is inserted into the mandible. In man and 
many other animals (though not in most) it becomes 
digastric or double-bellied, the intervening tendon being 
bound by an aponeurotic loop to the hyoid bone, and the 
muscle thus becoming an elevator of the hyoid as well as 
a depressor of the jaw. It arises from the digastric groove 
of the mastoid, and is inserted into the symphysis menti. 
With the lower border of the jaw its two bellies, which 
meet at an angle, bound the surgical triangle of the neck 
known as the submaxillary space. 
digastrieus (dl-gas'tri-kus), n. ; pi. digastrici 
(-si). [NL. : see digastric.] In anat., the di- 
gastric muscle. 
digby (dig'bi), n. ; pi. digbies (-biz). A smoked 
herring exported from the town of Digby in 
Nova Scotia; a Digby herring. 
Digenea 1 (di-jen'e-ii), n. [NL., fern, of "digene- 
us, < Gr. Styevfc, of two kinds or sexes: see 
digenous.~\ A genus of Asiatic flycatchers, of 
the family Muscicapidw, related to Niltara. D. 
supercitiaris of India is an example. Hodgson, 
1844. 
Digenea 2 (di-jen'e-a), n. pi. [NL., neut. pi. of 
*digeneus: see IMgenea^."] A division of trema- 
tode worms or flukes, containing those which 
leave the egg as free ciliated organisms : op- 
posed to Moiioe/enea. 
digenepus (di-jen'e-us), a. [< NL. *digcneus: 
see D/e( 2 .] Having the characters of the 
IHgenea; pertaining to the Digenea: as, a di- 
i/i'iicoiis fluke. 
digenesis (di-jen'e-sis), . [NL., < Gr. Si-, two-, 
+ yivtm<;, generation.] In Mol.. successive gen- 
eration by two different processes, as sexual 
