DIFFUSION. 237 DIGEST. a partial separation of the sulphates making up ordiuaiy alum may be eliected, the rates ol dif- fusion of the sulphates being quite dillerent. This does not apply, however, to electrolytic dissociation. (See Dissoci.vtion.) True, the ions of electrolytes possess, of themselves, different capacities for diffusion: thus, in a solution of hydrochloric acid, the electropositive hydrogen ions could diffuse much more rapidly than llie elect ro-negative clilorine ions. But their separa- tion by diffusion would cause one part of the solution to become charged with positive, the other with negative, electricity. In this manner an electro-static attraction would be established between the two parts of the solution, by the force of -which the different ions would again become nii.xed. In processes of electrolysis, how- ever, the electro-static attraction just mentioned is counteracted, and then the products of electro- lytic dissociation of acids, bases, and salts can actually be separated. See Osmosis ; Solution; Colloids. DiTFUsiox OF Solids. The diffusion of solid substances through one another is shown by a numtier of phenomena. Xot to speak of the even distribution of hydrogen gas through a mass of platinum or palladium, the surface of which has been exposed to the gas — solid carbon is known to be capable of passing through porcelain and to distribute itself evenly in a mass of iron. Further, solid barium sulphate and solid sodium carbonate have been shown to react with each other chemically — a process which could hardly take place unless the molecules of the two sub- stances became intimately intermixed by dif- fusion. Finally, experiments have been carried out on the diffusion of gold into lead at ordinary temperatures. At 18° C, gold has been found to diffuse upward, and. after a lapse of four years, traces of gold could be found at a distance of 7 millimeters from the surface of contact. DIGAM'MA ( Lat., Gk. Stya^^. from 5i-,di-, doub'e -r- 'jiixiia. gamma). The name given by grammarians not earlier than the first centurv A.D. to Vau. anciently the sixth letter of the Greek alphabet. The name is due to the form, double gamma. r. In the Ionic alphabet it was lost by the seventli century B.C., save as the nu- meral 6; the Chalcidian alphabet, however, re- tained it, and transmitted it, through Cuniie. to the Latins, with whom it lost its original sound (approximately our w). and became F. Even where it had ceased to be written, as in the Ho- meric poems, its influence can be detected, and often the cognate words in other languages than Greek show it, e.g. iinwrn = fotvos, wine. DIGBY. .^ port of entry and popular summer report, rapital of Digby Coimty, Xova Scotia, on the Bay of Fundy (Ma'p: Xov.a Scotia. Do). It has lumber and ship-building industries, a long pier, good bathing, boating, and fishing facili- ties, and a special reputation for a variety of small herrings or pilchards, known as 'Digby chickens.' which are cured for export, and have a high flavor. The United States is represented by a consular agent. Population, in 1891, 1381; in inni. 11.50. DIGBY, Oeorge, second Karl of Bristol (1012- 77 K An English legislator. He was bom in Madrid, was a member of the T.ong Parliament, and was one of the foremost opponents of Straf- ford. He was extremely vacillating by nature, and, after figuring as a champion of privilege, csi.oused the royal cause. In the Civil War he was for a time lieutenant-general of the royal army. During the Commonwealth he lived in France, where he rose to the rank of lieutenant-general, but was subsequently dismissed because of a political intrigue. After his return to England he was the accuser of Lord Clarendon, upon whom he endeavored to fasten a charge of high treason. He wrote the comedy Khira: or, The M'orst ^'ot Always True. DIGBY, Sir Ke.xelm (1603-U5). An English author and naal commander. He was born three years before the execution of his father, Sir Everard Digby. noted as one of the gun- powder plot conspirators. At the age of fifteen he was entered at Gloucester Hall, O.xford. Leaving the university in 1620, without a degree, he traveled abroad. Returning, he was knighted. In 1625 he married the celeoraled Venetia Stan- ley. In 1628 he equipped two ships at his owii expense, and sailed on a privateering expedition against the French and Venetians in the Jlcdi- terranean. He won a victory in the harbor of Iskanderim. In 1632, on the "death of Dr. Allen, of Gloucester Hall, Digby inherited his collection of books and manuscripts, which he presented to the Bodleian Library. In the troubles between JCing Charles and Parliament, Digby took the Royalist side, and was imprisoned in Winchester House, but in 1643 was allowed to retire to France. After Cliarles I. had fallen, Digby re- turned to England, bift Parliament forbade" him the kingdom, under penalty of death. Retiring to the Continent, he traveled in France and Italy; but in 1655 he was again in England, and was in frequent attendance at the Court of the Protector. He went again to France, and busied himself with the preparation of philosophical papers. He returned to England in 1661, and died there. His works are numerous, and on a great variety of subjects, comprising: A Con- ference with a Lady About Choice of Religion (Paris, 1638) ; Observations on Spenser's Fairy Queen (London. 1644) ; A Treatise on the Sovl, Proving Its Immortality (Paris, 1644) ; Of the Cure of ^'ounds by the Pouder of Sympathy (London, 1058) ; and Discourse on Vegetation (London. 1661), etc. The Private Memoirs of Sir K. Digby. etc., Written by Himself, were pub- lished in London in 1827. Consult: ".Journal of the Scanderoon Voyage," in Camden Society Pub- lications (London. 1868) ; and Poems, ed. War- ner (London. 1877). DIGBY, Kexelm Henry (1800-80). An Eng- lish writer. He was born in Ireland, graduated at Cambridge in 1819, and soon afterwards be- came a convert to the Roman Catholic Church. He published many works, chiefly on mcdianal theology-, or reflecting the spirit of the Middle -■Vges. The list includes: Mores Cafholici: or. Ages of Faith (11 vols., 1831-40) : Compitum: or. The Meeting of the Ways at the Catholic Church (7 vols., 1848-54) : The Broad Stone of Honor: or. Rules for the Gentlemen of England (1822) ; and Evenings on the Thames (2 vols., 1860). DIG'-DIG' or DIK'-DIK' (Arabic). See 0.ZF.LLK. DIGEST. A topical arrangement or compila- tion of legal rules, judicial decisions, or statutes.
