7 20 P E T P E T requirements from extreme laxity to unreasonable exaction, in con sequence of the lack of intelligent national Governmental action. Nearly all the nations of continental Europe have petroleum laws in the main based upon an intelligent appreciation of the subject, and but little inferior to English legislation. The Uses of NaplUlia. ^ lightest products obtained from petroleum are rhigolene, which is used in surgery, and cymogene, which is used as the volatile fluid in ice-machines. Gasolene is the lightest fluid obtained in considerable quantity, and is used in automatic gas - machines for the carburatiou of gas or air. The question of increasing the illuminating power of gas (see GAS, vol. x. p. 101), by causing it to absorb fluid hydrocarbons, was discussed as early as 1832, but it was only after petroleum furnished a cheap and suitable fluid that inventors succeeded in securing results of any value. While hundreds of machines have been patented in England, America, and continental Europe for accomplishing this purpose, it is only quite recently that an American inventor, Dr Walter M. Jackson, has succeeded in constructing a machine that satisfactorily meets all the requirements of the problem. His metrical carburetter measures both the fluid and the gas or air in such a manner that the least amount of the hydrocarbon fluid required to produce the effect sought is furnished to the gas, and the whole is immediately absorbed. By this means a uniform car- buration is secured, furnishing a gas of uniform quality, that never contains a sufficient amount of fluid to admit of condensation in any part of the apparatus. Both crude petroleum and the products of its manufacture have been used as a material for the manufacture of gas by distillation. The different qualities of naphtha are used in mixing paint, in the manufacture of oil-cloths for floors and of varnishes, as a solvent for gums and resins, in the preparation of alkaloids, in the manufacture of india-rubber, in washing wool, and in removing oils and grease from seeds and textile fabrics. Petroleum as Fuel. In the region of the Caucasus and on the Caspian Sea, where other fuel is scarce and dear and petroleum is plentiful and cheap, the latter is used with complete success on both steamships and locomotives. Petroleum and its products have been used with practical success in the manufacture of iron in the United States. Both illuminating oil and naphtha are now very widely used in stoves ; but naphtha -stoves are extremely dangerous, and their use should be prohibited by law. In the valley of the Euphrates, near Mosul, petroleum is used as a fuel in burning lime. Petroleum in Medicine. Although petroleum has been used as a remedial agent for an unknown period in the countries where it is a natural product, its physiological effects have never been very fully investigated. Barbados tar, Haarlem oil, Seneca oil, and American oil, all consisting wholly or in large part of crude petroleum, were sold by apothecaries for years before petroleum was obtained by boring. They were mainly used as liniments for external application, particularly in rheumatism. The oil of the Alleghany valley early had a local reputation as an internal remedy for consumption, and it has lately been prescribed for bronchitis. The most volatile product of petroleum obtained by distillation, called rhigolene, has been used to produce local insensibility, by means of the intense cold resulting from its rapid evaporation ; and the same fluid when inhaled as vapour or the gas escaping from fresh oil will produce an intoxication or insensibility resembling the effects of laughing-gas, resulting in death if its action is pro longed. The products of petroleum that have proved most valu able in medicine are the filtered paraffin residues sold under the names of cosmoline, vaseline, &c., that are now so widely used as ointments, either plain or medicated. They are of about the con sistence of butter, with very little taste or odour, and will keep indefinitely without becoming rancid. These valuable properties have caused them to almost entirely supersede all other prepara tions containing animal or vegetable fats. Looking towards the past, it may be said that petroleum has attained universal diffusion as a lighting agent ; it is fast displacing animal and vegetable oils as a lubricator on all classes of bearings, from railroad - axles to mule - spindles, and also where other oils are liable to spontaneous combustion ; it is very largely used as fuel for stoves, both for heating and cooking ; it is very successfully used for steam purposes when other fuel is scarce and petroleum plentiful ; it is likely to be used for the production of pure iron for special purposes ; and it has become a necessity to the apothecary as petroleum ointment. Looking towards the future, what assur ance have we that these varied wants, the creation of a quarter of a century, will be satisfied ? While it is not probable that the de posits of petroleum in the crust of the earth are being practically increased at the present time, there is reason to believe that the supply is ample for an indefinite period. Yet the fact is worthy of serious consideration that the production of petroleum as at present conducted is everywhere wasteful in the extreme. There are very few works that treat exclusively of petroleum. An article in the Bull, de la Soc. Ge.nl. de France, xxv., gives the best resume of the mention mafle by classical writers. Travellers overland to India and Persia have usually described Baku (see Kaempfer, 1712 ; Hanway, 1743; Foster, 1784; Kinnier, 1848). On the occurrence of petroleum in Burmah, see Journals of the Em bassies to the CourtofAva, Symes (1795), Crawfurd (1826), Yule (1855); in Persia, Carl Ritter s Erdk. v. Asien, 1840 ; in Japan, B. S. Lyman s Reports, Geolog. Survey o/V<ip(m,1874-75 ; in Galicia.Von Hauer (1853), Fotterle (1853, 1859, 1862), J. Moth (1873), Bruno Walter (1880), in Jahrbuchder K.-K. Geo. Reichsanstalt; in Roumania, Von Ilauer, Geologie Siebenburgens, 1863; H. Coquand, Bui. Soc. Geol. de France, xxiv. 505, 1807 ; in Canada, T. Sterry Hunt, in Reports of Geol. Survey of Canada of various dates, 1863-73; in Pennsylvania, J. F. Carll, Reports, I., II., and III., with maps, Second Geological Survey of Pennsylvania, 1874-1880. On the chemistry of petroleum, see C. M. Warren, in American Journal of Science and Chemical News ; Shorlemmer, in Quar. Journal of the Chemical Society ; Pelouze and Cahours in Ann. de Chimie et de Physique ; Berthelot in the same, all at various dates, 1863-1880. On the origin of petroleum, see Lesquereux, in Trans. Am. Phil. Soc., xiii., 1S66 ; J. S. Newberry, in Ohio Ag. Report, 1859 ; T. Sterry Hunt, in Chem. News, vi. 5 et sq.; Byasson, in Revue Industrielle, 1876; Mendeljeff, in Bull. Soc. Chim. de Paris, 1877. On testing petroleum, see John Attfield, in Chem. News, xiv. 257 ; F. Grace Calvert, Chem. News, xxi. 85 ; C. F. Chandler, in American Chemist, ii. 409 ; Boverton Redwood, in English, Mechanic and World of Science, xxii. 335, 1875 ; F. A. Abel, in Chem. News, xxxv. 73. On the general subject, see T. Sterry Hunt, "History of Petroleum or Rock Oil," in Canadian Naturalist, [1], vi. 245; Chem. News, vi. 5; Report of Smithsonian Institution, 1862 ; J. Lawrence Smith, in Report to the Judges of the. Centennial Exposition, Philadelphia, 1876; S. F. Peckham, monograph on petroleum, in cluding bibliography of petroleum and allied subjects to 1881, in Reports of the Tenth Census of the United States. See also, for an account of wells at Baku, Engineering, 22d February to 16th May 1884, London. (S. F. P.) PETROLOGY. See ROCKS. PETRONIUS. Petronius Arbiter, although excluded from the list of classical writers available for the purposes of education, is one who enjoyed a great reputation, especi ally in France, at a time when Latin authors were more read as literature than they are in the present day. A recent critic l of Petronius has stated, though with evident exaggeration, that no ancient writer except Aristotle has found so many interpreters. But there is perhaps none about whose history and era there has been so much controversy, nor is the controversy yet settled with abso lute certainty. He hides himself so completely behind the mask of his fictitious personages that we learn nothing of his fortunes, position, or even of the century to which he belonged, directly from himself. He does not belong to any of the classes of " viri illustres " (poets, orators, historians, philosophers, grammarians, and rhetoricians) whose lives were written by Suetonius. Though he is mentioned by critics, commentators, and grammarians of a late date (such as Macrobius, Servius, and Priscian), the only hint we have of anything bearing on his personal position is contained in two lines of Sidonius Apollinaris, a writer of the latter part of the 5th century A.D., who associates him with the masters of Latin eloquence, Cicero, Livy, and Virgil, in the lines " Et te, Massiliensium per hortos Sacri stipitis, Arbiter, colonum Hellespontiaco parem Priapo. " If these lines are to be construed as implying that Petronius lived and wrote his work at Marseilles, this inference could hardly be reconciled with the indirect evidence which leads to the identification of the author of the Satirx with the C. Petronius of whom Tacitus has painted so vivid a picture in the sixteenth book of the Annals (ch. 18, 19). His place of residence in his later years at least was not Marseilles but Rome. There is nothing, however, in what Tacitus says incompatible with the sup position that Marseilles was his birthplace ; or perhaps the allusion might be explained by the supposition supported by a note of Servius on Virgil, sEn., iii. 57 that the scene in the early part of the long novel, of which two fragmentary books have been preserved, was laid at Marseilles. The chief personages of the story, as they appear in these fragments of books xv. and xvi., are evidently strangers in the towns of the south of Italy where the adventures in which they share are supposed to take place. Their Greek- sounding names (Encolpius, Ascyltos, Giton, &c.), and their literary training also, accord with the character istics of the old Greek colony in the 1st century A.D. The high position among Latin writers assigned by Sidonius to Petronius, and the mention of him by Macro bius in juxtaposition with Menander, when compared with the absolute silence of such writers as Quintilian, 1 J. N. M. De Guerle, Recherches Sceptiques sur le Satyricon.
