538 SYLVIUS SYMBOLS terrestrial and celestial globes to illustrate his lessons, and a steam organ to explain his les- sons on music ; and he is said to have intro- duced the use of the Arabic figures in arith- metic, and to have invented the first wheel and weight clock. He was subsequently ap- pointed abbot of Bobbio by Oth o II. ; but being unable to agree with the monks, he re- turned to Rheims after the death of Otho, resumed his teaching, and became secretary to Archbishop Adalberon of Rheims, and his successor through a contested election. He was deposed by Pope John XVI., and fled to the court of Otho III., who made him arch- bishop of Ravenna and had him elected pope, April 2, 999. He displayed uncommon zeal, talent, and severity in his administration. His universal knowledge caused him to pass for a magician. His letters, numbering 149, were published by Papire Masson (4to, Paris, 1621), and by Andre Duchesne in vol. ii. of his His- tories Francorum Scriptores. His complete works are published in vol. cxxxix. of Migne's Patrologie latine. See Bzovius, Silvester II. (4to, Rome, 1629) ; Hock, Gerlert, oder Pabst Sylvester II. und sein Jahrhundert (Vienna, 1837; French, Paris, 1842); and Milman, "Lat- in Christianity," vol. iii. SYLVIUS, Jaeobns, the Latinized name of a French anatomist, JACQUES DU Bois, born at Louville, near Amiens, in 1478, died in Paris, Jan. 13, 1555. He graduated as A. B. in 1531, delivered lectures, and was appointed profes- sor of medicine in the royal college of France in 1550. He is said to have originated the practice of injecting the blood vessels to fa- cilitate their dissection. The oblique fissure separating the anterior and middle lobes of the cerebrum is called from him the fissure of Sylvius. SYMBOLS, Chemieal, abbreviations of the chem- ical names of the elements, which are com- bined into formulas, with or without quanti- tative signs, to represent the composition of compound bodies. The idea of representing the names of chemical substances by conven- tional signs or abbreviations appears to be a very old one. The alchemists were in pos- session of a set of hieroglyphics by which the metals and the four so-called elements, fire, air, earth, and water, and indeed many other sub- stances, were designated. At a later period, as chemical knowledge became more consolidated, various modifications of the alchemistical no- tation were from time to time proposed, and adopted to a greater or less extent. Among these should be specially mentioned the sys- tem of notation offered in 1787 by Hassen- fratz and Adet, as an appendix to Guyton de Morveau's revised system of nomenclature, since its failure enables us the better to ap- preciate the peculiar excellence of the system which now prevails. Here was a system of symbols by no means devoid of ingenuity, and much more complete than any previous meth- od, published in connection with a new sys- tem of nomenclature, which was soon univer- sally adopted, and recommended by the com- mittee of the French academy by whom this nomenclature had been prepared ; yet it met with little or no favor among chemists, and was soon forgotten. This last remark applies as well to the symbols proposed by Dalton in 1808, in connection with his writings upon the atomic theory. None of these systems ever came into general use, nor does it appear that they were of much value as instruments of study even in the special cases in which they were employed. It is to Berzelius that chemical science is chiefly indebted for the simple and rational system of notation now in use, which has done so much to advance knowledge and to lighten the labors of chem- ical investigators. This system, in its first outlines at least, appears not to have been the result of any premeditated plan or special study, but to have followed incidentally as a natural result from the investigation of the combining proportions of bodies with which its author was occupied. Thus in 1814 he first mentions his symbols in a foot note to a memoir upon nitrous acid (Gilbert's Annalen der Physik, xlvi., 154), as convenient abbre- viations for expressing the composition of bodies, which he has himself frequently em- ployed in his private memoranda. Subse- quently a more complete exposition of the plan appeared in his Lehrluch, and in Poggen- dorff's Annalen, 1826, viii., 7. As a sign'to express the name and combining equivalent of an element, Berzelius chose the initial let- ter of its Latin name ; and in those cases where the names of several elements com- mence with the same letter, he annexed to the common initial the first of the following letters in the Latin name of the element which is peculiar to it ; thus, the symbol C indicates an equivalent of Carbon, Cl an equivalent of chlorine, and Cr an equivalent of chromium. (For a complete list of these symbols, see EQUIVALENT, CHEMICAL.) There are various other symbols used in chemistry, some to ex- press qualities as well as the atoms or mole- cules of substances, as, for instance, the signs which express the quanti valence of bodies. (See ATOMIC THEOET, vol. ii., p. 88.) The signs +, , and = are also used in chemical writing for the purpose of joining the sym- bols of the elements together in formulas, as K a O + H a S0 4 =K a SO + 2H, or O.H, 9 O 6 -H a O =C 8 HioO 6 . When united by the sign = the formulas are called equations. Thus the lat- ter formula is an equation which represents starch as being formed from the elements of glucose or grape sugar, by the abstraction of a molecule of water or of the elements of such molecule. The quantity of any substance is usually expressed by placing a numeral before it, whether the substance is an element or a compound, unless where the numeral is used to express the number of separate elements or substances which enter into the composition of
