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Rh spectra-spark, arc, phosphorescence and absorption; the evidence, however, cannot in all cases be accepted as conclusive, but when taken in conjunction with chemical tests it is the most valuable method.

Chemical Relations.-The rare earth metals were at first regarded as divalent, but determinations of the specihc heats of cerium by Mendeléeff and Hillebrand and of lanthanum and didymium by Hillebrand pointed to their t rival ency; and this view now has general acceptance. They are comparatively reactive: they burn in air to form oxides of the type Me2O3; combine directly with hydrogen at 2OOO*3OO° to form hydrides of the formula MH2 or MH3; nitrides of the formula MN are formed by passing nitrogen over the oxides mixed with magnesium; whilst carbides of the type MC2 are obtained in the electrolytic reduction of the oxides with carbon. In addition to the oxides MQOQ, several, e.g. cerium, terbium and neodymium, form oxides of the formula MO2. The sesquioxides are bases which form salts and increase in basicity in the order Sc, Yb, Tm, Er, Ho, Tb, Gd, Sm, Y, Ce, Nd, Pr, La; the latter hissing with water like quicklime.

The placing of these elements in the periodic table has attracted much attention on account of the many difficulties which it presented. The simplest plan of regarding them all as trivalent and placing them in the third group is met by the fact that there is not room for them. Another scheme scatters them in the order of their atomic weights in the last four groups of the system, but grave objections have been urged against this plan. A third device places them in one group as a bridge between barium and tantalum. This was suggested by Benedick in 1904 (Zeit. anorg. Chem., 1904, 39, p. 41), and adopted in Werner's table of 1905 (Bef. 38, p. 914), whilst in 1902 Brauner (ibid. 32, p. 18) placed the group as a bridge on a plane perpendicular to the planes containing the other elements, thus expanding the table into a three-dimensional figure. The question has also been considered by Sir William Crookes (J onr. Chem. Soc., 1888, 53, p. 487; 1889, 55, pp. 257 et seq.), whose inquiries led him to a new conception of the chemical elements.

REFERENCES.-For the general chemistry see R. Bohm, Seltene Erden (1905); Abegg, Handbuch der anorganischen Chemie (1906), vol. iii. (article by R. 'I'. Meyer); H. Moissan, Traité de chimie minérale (1904), vol. iii. (article by G. Urbain); Roscoe and Schorlemmer, Trealfse on Chemistry (1908), vol. ii.; P. E. Browning, Introduction to the Rarer Elements (1909); see also A. W. Stewart, Recent Advances in Physical and Inorganic Chemistry (1909). For the rare earth minerals see J. Schilling, Das Vorkommen der sellenen Erden im Mineralreiche (1904).

RAS, the Arabic for a &ldquo; head,&rdquo; hence a cape, promontory or headland; a common word in place names.

RASCAL, a term originally used in the sense of a rabble, especially descriptive of camp-followers or the dregs of an army, or of the lowest of the people; now only of a single person, in the sense of a rogue or knave. The origin of O.Fr. rascaille, modern racaille, from which the word came into English, is uncertain. The word was early used, in hunting, for the weaker or poorer male deer of a herd; the word has been connected with O.Fr. rascler, mod. racler, to scrape, rake, in the sense of the off-scourings of the herd.

RASHBAM (1085–1174), Jewish scholar, so called from the initials of his full name,, was a leading member of the French school of Biblical exegesis. He was a grandson of (q.v.), but differed in his method of interpretation. He wrote commentaries on the Pentateuch and some other parts of the Scriptures. Rashbam adopts a natural (as distinct from a homiletical and traditional) method; thus (in agreement with the modern school) Rashbam (on Gen. i. 5) maintained that the day began at dawn and not from the previous sunset (as later Jewish custom assumed). Another famous interpretation was Rashbam's view that the much disputed phrase in Gen. xlix. 10 must be rendered &ldquo; Until he cometh to Shiloh,&rdquo; and refers to the division of the kingdom of Judah after Solomon's death. Rashbam's notes on the Bible are remarkable for brevity, but when he comments on the Talmud&mdash;he wrote explanations on several tracts&mdash;he is equally noted for prolixity. (I. A.)

 RASHI (1040–1105), Jewish scholar. (son of Isaac), usually cited as Rashi from the initials of those words, was born at Troyes in 1040 and died in the same town in 1105. Legends concerning him are many. Isaac's wife, shortly before the birth of their famous son, was walking one day down a narrow street in Worms, when two vehicles moving in opposite directions seemed about to crush her. As she leant hopelessly against a wall, it miraculously fell inwards to make a niche for her. So with his education. Legend sends the student to southern France, and even on a tour of the world. At an inn in the Orient he cured a sick monk, who later on, as bishop of Olmütz, returned the kindness by saving the Jews from massacre. In fact, Rashi never went farther than from the Seine to the Rhine; the utmost limit of his travels were the academies of Lorraine. Situated between France and Germany, Lorraine was more French than German, and French was the common language of Jew and Christian. This is shown by the glosses in Rashi's works, almost invariably in French. He seems to have passed the decade beginning with 1055 in Worms, where the niche referred to above is still shown. Within this, it is said, Rashi was wont to teach. A small edifice on the east of the synagogue is called the “ Rashi Chapel,” and the “ Rashi Chair,” raised on three steps in the niche, is one of the objects of the pious admiration of pilgrims. At Worms Rashi worked under Jacob ben Yaqar, and at Mainz under Isaac ben Judah, perhaps combining at the same time the functions of teacher and student. Besides the oral tuition that he received, the medieval schools habitually kept the notes of former teachers. From these Rashi learned much, and probably he incorporated some of these notes in his own works. In the middle ages there was a communism in learning, but if Rashi used some of the stones quarried and drafted by others, it was to his genius that the finished edifice was due.

Rashi was twenty-five years of age when he returned to Troyes, which town thenceforward eclipsed the cities of Lorraine and became the recognized centre of Jewish learning. Rashi acted as rabbi and judge, but received no salary. Not till the 14th century were Jewish rabbis paid officials. Rashi and his family worked in the vines of Troyes (in the Champagne); in his letters he describes the structure of the wine-presses. His learning and character raised him to a position of high respect among the Jewries of Europe, though Spain and the East were long outside the range of his influence. As was said of him soon after his death: “ His lips were the seat of wisdom, and thanks to him the Law, which he examined and interpreted, has come to life again.” His posterity included several famous names, those of his grandchildren. Rashi had no sons, but his three daughters were women of culture, and two of the sons of Jochebed (see and ), as well as others of his descendants, carried on the family tradition for learning, adding lustre to Rashi's fame. The latter part of Rashi's life was saddened by the incidents connected with the first Crusade. Massacres occurred in the Rhinelands. According to legend, Rashi and Godfrey of Bouillon&mdash;of the foremost leaders of the Crusade&mdash;were intimate friends. Rashi died peacefully in Troyes in 1105.

Rashi was the most conspicuous medieval representative of the Jewish spirit. A century later Maimonides was to give a new turn to Jewish thought, by the assimilation of Aristotelianism with Mosaism, but Rashi was a traditionalist pure and simple. He was in no sense a philosopher, but he exemplified in his person and in his works the stored up wisdom of the Synagogue. Yet through all that he wrote there runs a vein of originality. Besides minor works, such as a recension of the Prayer-Book (Siddur), the Pardes and ha-Orah, Rashi wrote two great commentaries on which his fame securely rests. These were the commentaries on the whole of the Hebrew Bible and on about thirty treatises of the Talmud. His commentary on the Pentateuch, in particular, has been printed in hundreds of editions; it is still to Jews the most beloved of all commentaries on the Mosaic books. More than a