haying only a slight odor like that of fat-oils, while the hydrocarbons that are condensed after passing over have a very offensive odor. The very last distillates from all of the destructive distillations are called "cokings," and are distilled by themselves, yielding mainly crude lubricating oil. The carbon separated in the stills contains some caustic soda, which can be obtained as carbonate by burning the carbon and lixiviating the ashes. The sulphuric acid used in agitating the oils is known as "sludge," and is sometimes sold to the makers of superphosphate of lime, although it has been occasionally successfully reconverted into oil of vitriol. The following list includes the commercial products which have been made from petroleum, being those already mentioned, with the exception of cymogene, which is distilled from gasolene, and condensed by a pump:
1. Cymogene, specific gravity 110° Beaumé; boils at 32° F. (0° C.); used in ice-machines. 2. Rhigolene, sp. gr. 100° B.; boils at 65° F. (18.3° C.); extremely volatile, producing by its rapid evaporation a temperature of -19° F.; used as a local anæsthetic. 3. Gasolene, sp. gr. 97°, 90°, 88°, and 86° B., as required by the market. The very light gasolene is ordered in small quantities, probably for ice-machines. The others are used in gas-machines, for which they are admirably adapted, and for various exceedingly dangerous lamps and stoves designed for their combustion. 4. Naphtha, sp. g. 70° to 76° B.; boils at 180° F. (27° C.), when of 70° gravity; used in manufacture of oil-cloths, cleansing, as a solvent for paraffine, etc.; sometimes fraudulently mixed with the higher-priced illuminating oils, or with crude petroleum, to be again sold to the refiner; also sold, under various names, as a burning-fluid, notwithstanding the certain danger attending its use. 5. Benzine, sp. gr. 65° to 62° B.; the boiling-point for 65° B. is 300° F. (149 C.); used in making paints and varnishes. 9. Illuminating oil (kerosene), sp. gr. 45° to 50° B.; boiling-point for 45° B. is 350° F. (177° C.). "Astral" oil and "mineral sperm" are particularly safe varieties, freed with care from explosive compounds. 7. Lubricating oil. "Neutral" lubricating oil has a specific gravity of 29° B., and boils at 575° F. (301.5° C.). 8. Paraffine, sp. gr. 0.87°; fusing-point for commercial paraffine about 110° to 150° F. (43.3° to 65° C.), according to its purity; boiling-point about 698° F. (370° C.); used for making water-proof fabrics, candles, lubricators, matches, chewing-gum, etc.
The refined illuminating oil should be free from more volatile compounds, which cause it to give off vapors that explode when mixed with air and ignited. Dr. White, President of the New Orleans Board of Health, found that, on adding to oil which "flashed" at 113° F. one per cent. of naphtha, the mixture flashed at 103°; with two per cent. at 92°; with five per cent. at 83°; with 20 per cent. the oil itself burned at 50° ("Report on Petroleum to New York Board of Health," Dr. C. F. Chandler, 1871). Dr. Chandler has found that
