Peep-Show at St Petersburg, where we are easily reminded of Godfried Schalcken. Dietrich tried every branch of art except portraits, painting Italian and Dutch views alternately with Scripture scenes and still life. In 1741 he was appointed court painter to August III. at Dresden, with au annual salary of 400 thalers (<60), conditional on the pro duction of four cabinet pictures a year. This condition, no doubt, accounts for the presence of 52 of the master s panels and canvases in one of the rooms at the Dresden museum. These pieces enable the spectator, if careless of more serious occupation, to study the numerous varieties of a changing style. It is needless, perhaps, to add that Dietrich, though popular and probably the busiest artist of his time, never produced anything of his own ; and his imitations are necessarily inferior to the originals which he affected to copy. His best work is certainly that which he gave to engravings, A copious collection of these at the British Museum, produced on the general lines of earlier men, such as Ostade and Rembrandt, reveal both spirit and skill. Dietrich, after his return from the Peninsula, generally signed himself " Dietericij," and with this signature most of his extant pictures are inscribed. His death took place at Dresden, after he had successively filled the important appointments of director of the school of painting at the Meissen porcelain factory and professor
of the Dresden academy of artsDIEZ, Friedrich Christian (1794–1876), the founder of Romance philology, was born at Giessen, in Hesse- Darmstadt, March 15, 1794, and died at Bonn, May 29, 1876. He was educated first at the gymnasium and then at the university of his native town. There he studied classics under Welcker, who had just returned from a two years residence in Italy to fill the chair of archeology and Greek literature It was Welcker who kindled in him a love of Italian poetry, and thus gave the first bant to his genius. In 1813 he joined the Hesse corps as a volunteer and served in the French campaign. Next year he returned to his books, and this short taste of military service was the only break in a long and uneventful life of literary labours. By his parents desire he applied himself for a short time to law, but a visit to Goethe in 1818 gave a new direction to his studies, and determined his future career. Goethe had been reading Raynouard s Selections from the Romance Poets, and advised the young scholar to explore the rich mine of Provengal literature which the French savant had opened up. This advice was eagerly followed, and hence forth Diez devoted himself to Romance literature. After supporting himself for some years by private teaching, he removed in 1822 to Bonn, where he held the position of privat-docent, which is the lowest grade of the German professoriate. In 1823 he published his first work, An Introduction to Romance Poetry ; in the following year appeared The Poetry of the Troubadours, and in 1829 The Lives and Works of the Troubadours. In 1830 he was called to the chair of modern literature. The rest of his life was mainly occupied with the composition of the two great works on which his fame rests, the Grammar of the Romance Languages, 1836-1844, and the Lexicon of the Romance Languages Italian, Spanish, and French, 1853.
In these two works Diez has done for the Romance group of languages what Jacob Grimm has for the Teutonic family. In both cases much remains to be accomplished, many words and forms are not yet accounted for, some errors have already been pointed out, but all future philologists must build on the foundations which these two men have laid. " Nothing," says Max Miiller, " can be a better preparation for the study of the comparative grammar of the ancient Aryan language than a careful perusal of the comparative grammar of the six Romance languages by Professor Diez."
In order to appreciate the importance of Diez's work it is necessary to take a rapid glance at the history of philology in France. The earliest philologists, such as Perion and Henri Estienne, sought to discover the origin of French in Greek and even in Hebrew. For more than a century Menage s Etymological Dictionary held the field without a rival. Considering the time at which it was written (1650), it was a meritorious work, but philology was then in the empirical stage, and many of Menage s derivations (such as that of " rat" from the Latin "mus," or of " haricot " from " faba ") have since become by-words among philologists. A great advance was made by Raynouard, who by his critical editions of the works of the Troubadours, published in the first years of the present century, laid the foundations on which Diez afterwards built. The difference between Diez s method and that of his predecessors is well stated by him in the preface to his dictionary. In sum it is the difference between science and guess-work. The scientific method is to follow implicitly the discovered principles and rules of phonology, and not to swerve a foot s breadth from them unless plain, actual exceptions shall justify it ; to follow the genius of the language, and by cross-questioning to elicit its secrets ; to guage each letter and estimate the value which attaches to it in each position ; and lastly to possess the true philosophic spirit which is prepared to welcome any new fact, though it may modify or upset the most cherished theory.
Such is the historical method which Diez pursues in his grammar and dictionary. To collect and arrange facts is, as he tells us, the sole secret of his success, and he adds in other words the famous apophthegm of Newton, "hypotheses non fingo."
The introduction to the grammar consists of two parts:—the first discusses the Latin, Greek, and Teutonic elements common to the Romance languages ; the second treats of the six dialects separately, their origin, and the elements peculiar to each. The grammar itself is divided into four books, on phonology, on flexion, on the formation of words by composition and derivation, and on syntax.
His dictionary is divided into two parts. The first contains words common to two at least of the three principal groups of Romance,—Italian, Spanish and Portuguese, and Provencal and French. The Italian, as nearest the original, is placed at the head of each article. The second part treats of words peculiar to one group. There is no separate glossary of Wallachian.
Of the introduction to the grammar there is an excellent translation into French by Gaston Paris, a pupil of Diez, and an English translation by C. B. Cayler. The dictionary has been published in a remodelled form for English readers by T. C. Donkin. A second edition, enlarged and corrected, appeared in 1861, and a third edition was begun in 1869.
DIFFERENTIAL CALCULUS. See Infinitesimal Calculus.
DIFFUSION. Some liquids, such as mercury and water, when placed in contact with each other do not mix at all, but the surface of separation remains distinct, and exhibits the phenomena described under Capillary Action. Other pairs of liquids, such as chloroform and water, mix, but only in certain proportions. The chloroform takes up a little water, and the water a little chloroform ; but the two mixed liquids will not mix with each other, but remain in contact separated by a surface showing capillary phenomena. The two liquids are then in a state of equilibrium with each other. The conditions of the equilibrium of heterogeneous substances have been investi gated by Professor J. Willard Gibbs in a series of papers published in the Transactions of the Connecticut Academy of Arts and Sciences, vol. iii. part i. p. 108. Other pairs of liquids, and all gases, mix in all proportions.
