Albertite of New Brunswick was also being distilled on the Atlantic coast, while west of the Alleghenies cannel coal was being distilled at Cannelton, on the Kanawha river, in West Virginia; at Cloverport, on the Ohio river, in Kentucky; at Newark, O., and near Pittsburgh, Pa. The experiment of distilling oil from Devonian pyroschists was also made at Erie, Pa. They yielded fifty gallons of distillate to the ton. Without exception every one of these materials yielded paraffine, and when the petroleum obtained from Pennsylvania and West Virginia was used as a substitute, it was found that it yielded identical products, and the coal-oil industry was quickly rendered unprofitable. In an attempt to utilize all available material, William Atwood, who was one of the most skillful technologists in coal oil, was sent to the Island of Trinidad, where a plant was constructed and an unsuccessful attempt made to prepare illuminating and lubricating oils from Trinidad pitch. The pitch furnished distillates very different from the paraffine products obtained in the United States.

During the last years, before the coal-oil industry ceased to be profitable, a number of patents were granted for improvements in this technology, mainly for improved methods of distillation. The aim of these inventions was to effect a uniform heating of the material by which a slow distillation at low temperatures would be promoted. The presence of steam, often superheated, was found to be at all times beneficial. While to produce gas from these materials, it was found necessary to thrust them into a retort heated to a high temperature; to produce oil, it was found on the contrary best to distill at the lowest temperature possible. The intermediate oils, too dense for illumination and too light for lubrication, accumulated in the refineries, until Joshua Merrill discovered that by distilling them in such a manner that the vapors were superheated the vapors were "cracked" or "dissociated," and when they were condensed they were found to be of such a specific gravity that they could be used for illumination. This was the most important discovery ever made in the technology of bitumens, and when applied to the manufacture of paraffine petroleums it was of enormous value.

Soon after 1860, attempts were made to treat the bitumens of southern California by the same methods of distillation that were employed in treating paraffine oils, but all the results obtained showed that the processes were being applied to different materials

and the results were different. These results all pointed to an excess of carbon and more unstable compounds. On analysis these crude oils were found to contain a large percentage of nitrogen as compared with paraffine petroleums.1

Canadian petroleum had been known to contain sulphur and to be difficult to refine. When similar oils were obtained in large quantities about 1885, in western Ohio, the sulphur petroleums became a serious problem in the technology of bitumen, as it was commercially desirable to treat them in the same manner as the pure paraffine petroleums of Pennsylvania. During 1893 and 1894, the technology of California bitumens was again investigated. Destructive distillation when applied to these bitumens, resulted in the production of a large volume of gas and asphaltic residuums with a distillate consisting principally of unsaturated hydrocarbons. The crude oils were found to be allied to the crude oils produced in the Scotch shale-oil industry, as they contain a large percentage of nitrogenous basic oils."

There were thus established among North American bitumens three great classes: those known as Pennsylvania oils," consisting of nearly pure paraffines, for which I have elsewhere proposed the name of Warrenite; those known as "Lima oil," which together with the Canadian oils contain a notable proportion of sulphur compounds, for which I have proposed the name of Maberyite, and the California oils, which occur in great variety and, while containing sulphur, are characterized as nitrogen bitumens and for which I have proposed the name of Venturäite. There is also a class of bitumens not yet investigated that are found on the eastern slope of the Rocky mountains from Mexico to the Arctic circle. In Europe, the paraffine petroleums of Galicia appear to be quite distinct from the bitumens of the Caspian sea. Technology has also divided bitumens into two great classes that are largely determined by geological occurrence. The great petroleum region of North America, which is by far the most important in the world, lies in the great palæozoic basin that surrounds the Cincinnati anticlinal; while the bitumens of California, the West Indies and Europe issue from Tertiary rocks. These Tertiary bitumens are found in much greater

1 S. F. Peckham, Reports Geol. Surv., California, "Geology," ii, Appendix, P. 73.

2 S. F. Peckham, Am. Jour. Sci. (3), xlviii, 250.

variety and are uniformly more difficult to refine into commercial articles than the bitumens obtained from older formations.1

It is proper to mention in this connection three classes of investigations that have been made on a commercial scale. The first was made about 1860-65, by Cyrus M. Warren, and consisted in distilling destructively the lime soap made from menhaden (fish) oil.

The products of this distillation were refined into illuminating oil, in all respects identical with coal oil and refined petroleum; and they were also proved by an elaborate research to contain the same constituent hydrocarbons. Quite recently, Prof. Karl Engler, has repeated these experiments with the addition of pressure and steam during distillation. Warren's results were confirmed. Still more recently, Dr. S. P. Sadtler has discovered that the vapors escaping from linseed oil while being boiled furnish, when condensed, a petroleum-like liquid, which upon examination was found to consist of hydrocarbons identical with those found in Pennsylvania petroleum. It is an honor to American science that these results, valuable and interesting alike to science and technology, were obtained by American investigators."

The general conclusion from technology appears to be, that for commercial purposes, crude bitumens and the products of their distillation may be duplicated by products of the destructive distillation of pyroschists, wood, coal, peat and a great variety of animal and vegetable substances.

13. It would be entirely unnecessary for my present purpose to notice in detail all the researches that have been undertaken upon bitumen, in all its various forms, since de Saussure published his paper on the Naphtha of Amiano, in 1817. It is sufficient to indicate along what lines the investigations have proceeded and in what manner the results have been interpreted. The earliest investiga

1 Boverton Redwood, Petroleum, etc., London, Charles Griffin & Co., 1896, ii. S. F. Peckham, PROC. AM. PHIL. Soc., x, 445. Repts. 10th Census, U.S., x. “Petroleum,” Am. Jour. Sci. (3), xlviii, 250 and 389, 1, 33. Science xxiii, 74. Four Frank. Institute, Nov., 1895. S. P. Sadtler, Am. Jour. Pharm., Sept., 1896. C. F. Mabery, Jour. Frank. Institute, cxxxix, 401. Proc. Am. Acad., n. s., xxiii. Am. Chem. Jour., xix, 243, 374, 419,796. B. Silliman, Jr., Am. Jour. Sci. (ii), (xliii,) 242. Chem. News, xvii, 257. Bul. Soc. Chem, de Paris, 1868, p. 77.

2 C. M. Warren and F. H. Storer, Mem. Am. Acad., n. s., ix, 177. Karl Engler, Berichte der Deut. Chem. Gesellschaft, 1888, xxi, 1816, xxii, 592. Dingler, Poly. Jour., 1889, p. 271. S. P. Sadtler, Am. Jour. Phar., Sept., 1896.

tors analyzed bitumens as if they were homogeneous substances. They determined the carbon and hydrogen, added the percentages together and subtracted the sum from one hundred, calling the deficit oxygen. This went on for nearly fifty years. It is true that Prof. B. Silliman, Jr., fractionated petroleum by distillation, and queried whether the liquids that he obtained were educts or products. It was not until 1863 that Schorlemmer, in England, and Pèlouze and Cahours, in France, published researches that professedly separated the compounds that were mixed together in petroleum. They were soon followed by Warren and Storer in the United States, who, by a superior method of condensation, succeeded in separating the hydrocarbons in coal-tar naphtha, naphtha from Pennsylvania and Rangoon petroleum, naphtha from lime soap of menhaden oil and also the hydrocarbons from oil of cumin. These researches established the existence in these liquids of several series of hydrocarbons, the members of which were identical, whether obtained from natural or artificial substances, and were also in many cases recognized as identical with chemical compounds already well known.1

Since these results were published, a great amount of work has been done with varying success upon a great variety of petroleums, in which work progress has been observed along two lines, viz., first, better methods of separation, and second, better methods of ultimate analysis. It is only quite lately, however, that Prof. C. F. Mabery has succeeded, by distilling in vacuo with Warren's hot condenser, in so completely avoiding decomposition by cracking as to reach results that are final. While this is said without any wish to disparage the work of other investigators, it must be said with a proper regard for truth. There is, however, a vast amount of chemical research on record, a very complete résumé of which can

1 Theo. de Saussure, Ann. Chim. et de Phys. (2), iv, 314–320. London Jour. of Sci., iii, 411. B. Silliman, Jr., Am. Chemist, ii, 18. Moniteur Scientifique, No. 366. Am. Jour. of Gas Lighting, xvi, 83. Wagner's Ber., 1872, p. 848. C. Shorlemmer, Chem. News, 1863, viii, 157; xi, 255. Am. Jour. Sci. (2), xxxvi, 115. Rep. de Chim. Appliqueé, 1863, p. 174. Jour. für Phar., xxi, 320. J. Pelouze and Aug. Cahours, Comptes Rendus, lvi, 505; lvii, 62. Ann. de Chim. et de Phys. (4), i, 5. Am. Jour. Sci. (2), xxxvi, 412. C. M. Warren and F. H. Storer, Mem. Am. Acad., n. s., ix, 121–176. Am. Jour. Sci. (2), xxxix, xl and xli. Chem. News, xii, 85, 261, et seq.

2 C. F. Mabery, Proc. Amer. Acad., n. s., xxiv; Amer. Chem. Jour. xix, 243, 374, 419.

be found in the exhaustive work of Mr. Boverton Redwood, which has given results sufficiently accurate for my purpose. These results may be generalized as follows:

The Pennsylvania petroleums are the purest paraffine petroleums known. They contain small percentages of olefines and traces of benzoles. The same hydrocarbons have been found in other petroleums, in the distillates from cannel coal, pyroschists, peat, wood tar, fish-oil soap, fish oil under pressure and linseed oil, and also from grahamite, albertite, ozocerite and many other substances of mineral and organic origin.1

The Lima and Canadian petroleums contain the paraffine series, with a notable proportion of sulphur derivatives of the paraffines, formed by substitution; and also traces of benzoles and nitrogenous basic oils.2

The Russian oils contain the benzole hydrides and naphthenes." The California oils, so far as at present known, consist of the benzole hydrides, naphthenes, benzoles and sulphur substitution compounds with a large percentage of esters of nitrogenous basic oils.'

The Scotch shale oils contain paraffines, olefines, benzoles and esters of nitrogenous basic oils."

These esters are also found in coal tar and in Dippel's oil, the latter being an oil obtained as a distillate from the gelatine of bones.

No satisfactory research has ever been undertaken upon semifluid malthas or solid asphaltums. They cannot be distilled without decomposition, and no analysis by solution has yet been made that was not highly empirical. It is assumed, rather than proved, that many solid bitumens contain oxygen. They certainly do contain sulphur, and in some instances they contain nitrogen. When distilled upon the large scale solid bitumens are decomposed and 1 Schorlemmer, Pelouze et Cabours, Warren and Storer, Mabery, loc. cit. Mabery and Smith, Proc. Amer. Acad., n. s., xxiii; Amer. Chem. Jour., xvi, 83, 89, 544; xvii, 713; xix, 419.

3 Beilstein and Kurbatow, Ber. d. D. Chem. Ges., 1880, p. 1818. Jour. Amer. Chem. Soc., xiii, 232. Markonikow and Oglobini, Ber. d. D. Chem. Ges., xviii, 2234; Ann. de Chim. et de Phys. (6), ii, 372.

S. F. Peckham, PROC. AMER. PHIL. SOC., x, 445; xxxvi, 154; Amer. Jour. Sci. (3) xlviii, 250. C. F. Mabery, Jour. Frank. Inst., cxxxix, 401. Boverton Redwood, Petroleum, i, 203.

5 English patents.