234 



KNOWLEDGE 



[December 1, 1891. 



occurrence of this oil there is no need to speak, the names 

 Petroleum, rock oil, and Naphtha (Persian nafata—to exude), 

 being sufficiently indicative of its origin. There is probably 

 no country in tlie world that does not possess Petroleum- 

 bearing strata, but the comparative small expense with 

 which the Amarican and Russian springs can be worked 

 keeps out from the market oils which cost more to obtain. 

 The Russian oil trade is conducted on the simplest lines 

 possible. Pipe lines are laid down to conduct the oil from 

 the wells to the refineries. Thus between Balakhani and 

 Baku there are some seven lines of cast-iron pipes of six 

 inches diameter, and through these pipes there Hows in a day 

 2,000,000 gallons of Petroleum. The process of purifying 

 is a simple one, and merely involves the employment of a 

 series of stills, each one of a higher temperature than the 

 precedmg one. In one of these stills the Petroleum loses 

 a portion of its constituents, in one the more volatile oils, 

 in another the parafiin ; further on, the heavy lubricating 

 oils, and last of all there is the " residuum,'' as it is styled 

 in America, or " astatki " by the Russian distillers. The 

 commercial value of this residue it is at present difficult to 

 assess, but many engineering experts are of opinion that 

 it is far superior to coal as a steam raiser. 



The type of vessel which the conditions of the Petroleum 

 trade has called into existence is that aptly described as 

 the tank steamer, which is simply a vessel divided by 

 transverse bulkheads into watertight compartments or 

 tanks, in which the oil is carried in bulk. The tanks may 

 be divided by a longitudinal bulkhead, which reduces their 

 size to one half. Expansion tanks are provided, and man- 

 holes give the men free access to the tanks. lu tank 

 steamers the propelling engines are aft, and two bulkheads, 

 with a space between them, are interposed between the 

 aftermost tank. The object of this is to supply a chamber 

 into which the leakage fro.u the tanks may collect, as well 

 as oppose a barrier between the engine space and the oil 

 tanks. Cases are on record where the leaked oil has found 

 its way into the bunkers, with the result that the coals 

 were saturated with oil, and great risk of explosion incurred. 

 Where this intervening space is stored with water the oil 

 accruing from leakage can be easily removed, as by reason 

 of its lesser specific gravity it finds its way to the surface 

 and can be skimmed otf, and thus the generation of the 

 dangerous Petroleum vapour is obviated. Tank steamers 

 are fitted with electric light, and the double wire 

 system is being extensively adopted in preference to 

 the more questionable method of employing the single 

 wire with the iron hull of the vessel as the return. The 

 danger of the latter system of installation often militates 

 seriously against successful navigation ; as, apart from 

 other risks, the single wire system has been known to 

 produce an error in the ship's compass of from 3^ to 7^. 

 Where portable lights are required on a Petroleum shij), 

 wires are switched on to the main cable, and the lamp is 

 usually protected by a strong glass container and a stout 

 wire protector. iSuch are briefly the outlines of the 

 existent machinery for the over-sea transit of Petroleum 

 in bulk. 



It is somewhat remarkable that the destruction of 

 Petroleum vessels by explosion and tire does not seem to 

 be brought about directly by the cargo itself, but rather by 

 the residual vapour which remains in the hold spaces 

 when the oil is partially or wholly discharged. 



The dangerous character of this vapour is well known, 

 and its accumulation m a space employed to carry 

 quantities of crude oil not yet deprived of its most volatile 

 constituents must be regarded as an inevitable adjunct to 

 the risks of Petroleum carriage. The maximum danger in 

 the case of tank steamers is reached after the discharge of 



the oil has taken place, for the oleaginous properties will 

 ensure its adhering to the sides of the tanks when the 

 pumps have removed all they can. One volume of this 

 crude oil is sufficient to render feebly inflammable 2-400 

 volumes of air, and the exposure of such a great evaporating 

 surface supplies the most favourable conditions for the 

 generation of Petroleum vapours. In the bottoms of the 

 tanks there is usually some inches of oil which remains 

 even after the tanks have been filled with sea water and 

 pumped out again. Evaporation must of necessity go on 

 rapidly from such a shallow surface, and the result is that 

 the tank becomes, unless adcijiuite means are employed to 

 cleanse and ventilate, a danger space of the most 

 pronoimced type. 



A brief sketch of three typical disasters occurring on 

 Petroleum vessels wUl show the glaring deficiencies of the 

 precautionary measures at present adopted in the Petroleum 

 carrying trade. On the 19th December, 1889, the steam- 

 ship Ferfiusons was discharging at Rouen a cargo of crude 

 oil, shipped at Philadelphia, when a fearful explosion took 

 place, blowing out the mainmast and completely wrecking 

 the after-part of the vessel. In spite of all efi'orts to ex- 

 tinguish the flames the fire raged until the next day, when 

 the vessel foundered. No trace could be discovered of one of 

 the tank men who was below at the time of the disaster. 

 Her Majesty's Consul at Rouen forwarded to the Home 

 Office a sample of the crude oU carried by the Fcnjusom, 

 and this, on examination by Dr. Dupro, chemical adviser 

 to the Explosives Department of the Home Office, was 

 found to have at the normal temperature a sx^ecific gravity 

 of -7925. This crude oil contains all the most volatile 

 constituents of Petroleum, and this particular samijle was 

 capable of rendering inflammable 2400 times its own 

 volume of air. Thus, a gallon would suffice to render in- 

 flammable 400 cubic feet of air, and its volatility may be 

 judged of bj' the fact that the exposure of one foot of oil 

 surface for twenty minutes will make thirteen cubic feet of 

 air explosive. Now, although the employment of electric 

 lighting on oil ships tends in the main to minimize risk, yet 

 imperfect installation supplies a ready method of igniting 

 this Petroleum vapour. At the time of the disaster 

 the dynamo was running, and there is little doubt that 

 the emission of a spark consequent upon the faulty con- 

 tact of the portable cable and lamp led to the disaster. 



Some little while after this the nautical world was 

 startled by the news of a disaster almost without a 

 parallel in the annals of our mercantile marine. A tank 

 steamer, the WUddowcr, constructed in 1889 for the 

 Petroleum trade and fitted with six cargo tanks, each 

 holding 500 tons weight of oil, was engaged to con- 

 vey a cargo of crude Petroleum from Philadelphia to 

 Rouen. The voyage was accomplished in safety, and the 

 discharge of the oil was effected satisfactorily until the 

 pumps sucked, leaving in the tanks a depth of oil varying 

 from two to six inches, while in one tank there was some 

 fifteen inches of the crude oil left. Two of the tanks 

 were pumped full of water. The vessel then left Rouen, 

 and on -Tanuary 8th, 1890, she arrived in the Wear, where 

 she was moored. The tanks were then pumped out, and 

 it was noticed that an oily film spread over the surface of 

 the Wear and was carried seawards by the ebbing tide. 

 Hardly were the pumping operations concluded when an 

 alarm of fire was raised, and the surface of the water in 

 the vicinity of the vessel was covered with smoke and 

 flame. The adjacent shipping was much damaged, the 

 surging flames enveloping them and extending seventy 

 feet into the air, burning the rigging and buckling the 

 stout iron plates with most disastrous effects. One hfe 

 was lost. Most probably the firing of the oleaginous 



