Modern Gasworks Practice

 729 WATER GAS Distillates from American Gas Oil (Specific gravity, 0-8520.) Temp. 0° C. Per cent, by Volume. Specific Gravity. Characteristics. Up to 120° 120° to 200° .... 200° to 225° .... 225° to 240° .... 240° to 260° .... 260° to 275° .... 275° to 300° .... 300° to 350° .... 350° to 380° .... 380° to 400° .... Residue Löss on distillation . 0-5 10 90 7-0 16-0 6-5 16-0 25-0 14-5 3 0 0-5 10 0-7790 0-7881 0-7886 0-8224 0-8373 0-8409 0-8517 0-8610 0-8980 0-9130 Clear white Do. Do. Pale straw colour Do. Yellow Greenish yellow Do., slightly viscous Dark green, viscous Dark red, glutinous Black solid 100'0 per cent. (Note.—Sulphuretted hydrogen evolved throughout distillation.) With regard to gasworks tests, the only true indication of the suitability of an oil is a practical trial run by an engineer who knows the ins and outs of the working of his plants. Oils have frequently been known to give satisfactory laboratory tests in every way, and yet to yield unsatisfactory results. Petroleum, being a natural product, is liable to considerable variation, and no agents for gas oil will guarantee results or candles per gallon.” For American oilsthe specific gravity should fall between 0-845 and 0-865 ; but within recent years there has been. a growing tendency to remove a greater quantity of the lighter constituents owing to their enhanced value. Specific gravity, therefore, bas increased and now frequently approaches 0-90. The test for flash point is important, owing to the faet that if this falls below 73° F. a special licence for storing is required, while higher rates will be demanded for railwav carriage. The test may best be carried out by means of the Abel “ closed ” apparatus, and affords a fair indication as to the percentage of volatile constituents. The details of the test need not be described here, and it will be sufficient to recall that the flash, point of an oil is the temperature at which it gives off sufficient vapour to ignite momentarily on the introduction of a spark or flame. The oil is heated at a prescribed rate, and a definite ignition agent is applied in a given männer. One of the most satisfactory methods of testing a gas oil destined for water-gas manufacture is to ascertain by fractional distillation whethei or not it is of a homo-geneous nature; that is to say, not merely a mechanical mixture of different oils likely to separate out when stored in. a tank. A suitable liomogeneous oil would give fractions coming away with fair regularity between the second and eighth or ninth. 10 per cent, periods. The proportion of the oil distilling over at a temperature