OXFORDSHIRE 30,544; to professors, 13,500; to fellows, 101,171 ; to scholars and exhibitioners, 26,- 226; all other expenditures, 242,402. Be- sides the revenues above mentioned, the uni- versity, colleges, and halls have in their gift 444 benefices, with an income of 188,695. OXFORDSHIRE, a S. county of England, bor- dered S. and S. "W. for 70 m. by the river Thames or Isis, and enclosed by the coun- ties of Warwick, Northampton, Buckingham, Berks, and Gloucester ; area, 735 sq. m. ; pop. in 1871, 177,956. It is very irregular in out- line, and the surface is greatly varied. In the southeast are the Chiltern hills, abound- ing in forests and tracts of fertile land; the central and northern portions, with the ex- ception of a not very elevated ridge, are most- ly flat, but well cultivated. The principal riv- ers are the Thames, or Isis (by which latter name it is known until it is joined by the Thame), the Evenlode, Windrush, and Cher- well. The soil is generally very fertile, and the population is principally engaged in agri- culture, especially in dairy husbandry. The county has long enjoyed a reputation for its beautiful woods, and the abundance of its mea- dows and pastures. There are many interest- ing antiquities. The principal towns are Ox- ford, the capital, Woodstock, and Banbury. OX GILL, the bile of the ox, a viscid green or greenish yellow fluid, of bitter and slightly sweetish taste, found chiefly in a membranous bag in the ox. It varies in consistency, some- times being very limpid, and at others like a sirup. (See BILE.) It possesses properties which render it of value in the arts. It dissolves greasy matters, and for cleansing woollen stuffs upon a large scale it is sometimes preferred to soap. To preserve it from putrefying it need only be evaporated at a gentle heat to the con- sistency of an extract ; and when wanted for use it may be dissolved in water slightly alka- line. The purified ox gall is much used by artists on account of its property of combining with colors, giving them more tenacity and fix- ing them strongly, while it also makes them flow more freely and often increases their lus- tre. It may either be mixed with the colors or applied to the paper after the colors. It is advantageously applied combined with gum Arabic as a light varnish, which however ad- mits of other shades being added without mix- ing with the first. With lampblack and gum water it makes a beautiful black paint or ink that may be used instead of India ink. The lampblack is first mixed with the gum water, and the purified ox gall is then added. It fixes sketches in lead pencil, and does not prevent them from being afterward tinted with colors in which a small proportion of ox gall is mixed. It is highly recommended for use in painting on ivory, as it removes from this all greasy matter, and causes the colors to spread freely, and penetrate into the ivory. It is equally useful in the application of paints to trans- parent paper. For these effects it is essential 626 VOL. xii. 49 OXIDES 767 that the purified article should be prepared from very fresh ox gall. The method of puri- fying in best repute is as follows : To a pint of the gall boiled and skimmed add an ounce of pulverized alum, and leave the liquor on the fire till the combination is complete. Another pint is treated in the same way with an ounce of common salt instead of alum. When cold the liquids are separately bottled and loosely corked. They should then be kept for three months, when a sediment subsides, and the liquor becomes clearer. There is still present a yellow coloring matter which would affect green and some other colors, and which is sepa- rated as a coagulum by turning off and mixing the clear portions of the two mixtures in equal quantities. The liquid is then obtained by fil- tering perfectly purified and colorless. It im- proves by age, and never disengages a bad odor, nor loses its useful properties. OXIDES, a general term applied to the com- Eounds of oxygen with other bodies, particu- irly the binary compounds with the other elements. Their number and variety are very great, for oxygen is the most widely diffused and abundant of all the elementary substances. Water is an oxide of hydrogen, and the geo- logical formations are principally composed of various oxides of the metallic and non-metallic elements, as oxide of silicon or silica in quartz rock, oxide of iron in various iron ores, and oxides of aluminum and silicon in clay and feldspathic rocks. The oxides exist in all three of the physical forms of matter, the solid, liquid, and gaseous. The metallic oxides are solid at ordinary temperatures, and most of them retain this state at high temperatures. Oxide of hydrogen, water, is a liquid at the common pressure of the atmosphere between 212 and 32 F. ; above 212 it has a gaseous, and below 32 a solid form. The oxides of carbon, carbon monoxide and carbon dioxide, commonly called carbonic oxide and carbonic acid, are gases, the former never having been liquefied. Carbonic acid has, however, been liquefied and frozen. (See CAEBONIO ACID, and HEAT.) According to the proportion of the number of equivalents with which oxygen enters into union with other bodies, the oxides receive the names of monoxide or protoxide, dioxide (deutoxide or binoxide), teroxide or tritoxide, tetroxide, pentoxide, and also subox- ide and peroxide, for lowest and highest ox- ides. The series of oxides of some of the ele- ments are remarkable for regularity of compo- sition, as the oxides of nitrogen and manganese. (See NITEOGEN, and MANGANESE.) The^oxides are conveniently divided into three principal groups, the first containing all those which re- semble the oxides of potassium, sodium, silver, and the lower oxides of lead, and which are called basic oxides or bases. In the second group the oxides of sulphur and phosphorus may be taken as types. They are called acid oxides, and are capable of uniting with the basic oxides and forming compounds called
