70 



KNOWLEDGE. 



March. 1915. 



13th. — The Ivy-leaved Speedwell is Veronica hederaefolia. The Lesser Celandine is not a Chelidonium, 

 but is Ranunculus ficaria. Wood-sorrel is Oxalis acetoseUa. The frog and toad mentioned 

 will be the common species in each case, namely, Rana tcmporaria and Bufo vulgaris. 



14th. — The JMarsh Marigold is Caltha palustris. The Violets are Viola odorata, and the Meadow- 

 sweet, Spiraea ulmaria. 



15th. — Chrysanthemum partheniuin is the name by which the Feverfew now goes. The Larch is 

 Larix europaea. 



17th. — The Guelder Rose is Vihurum opidus, and the Coltsfoot, Tussilago farfara. Gilbert White is 

 careful to add after his supposed record of the tuberous Moschatel that the plant was 

 Sanicle, Sanicula europaea. The Pig-nut is Carum hulhocastanum. 



19th. — The Wych-elm is Ulnius montana. Soapwort is Saponaria officinalis. The Sloe we now 

 know as Primus communis. The Butcher's Broom is Ruscus aculeatus, and the Wood-ant, 

 Formica rufa. 



21st. — Ulmus campestris is the name which is now used for the Common Elm. 



28th. — The Hazel is Corylus avellana. 



THE HISTORY OF THE SCOTTISH SHALE OIL INDUSTRY. 



By S. C. BRADFORD, B.Sc. 



Most of the oil fuel now used for naval purposes comes 

 from Russia, America, or Canada ; but it is not generally 

 known that a certain proportion is produced by the 

 destructive distillation of bituminous shale in Scotland, 

 nor that the first paraffin oil to be used on any considerable 

 scale for lighting purposes came from the same source. 

 With the eventual exhaustion of petroleum springs, this 

 method will necessarily be generally adopted, and it is 

 remarkable that in a textbook on liquid fuel, only just 

 published, no mention is made of the subject. 



As early as 1781 Lord Dundonald showed how to prepare 

 oil from bituminous shale, but no attention was paid to 

 his work ; and it was not until 1830 that Reichenbach 

 discovered solid paraffin. In 1839 the manufacture of the 

 latter was attempted in France by Sellique, who six years 

 later proposed a method for making it into candles. There 

 was, however, no demand for the products, and solid 

 paraffin remained little more than a laboratory curiosity, 

 until, in 1850, James Young took out his first patent for 

 the low-temperature distillation of coal, from which time 

 the history of the Scottish shale oil industry may justly 

 be said to date. 



Two years previously Young had started a works for 

 refining the petroleum from a spring in Derbyshire. This 

 supply, however, yielded only three hundred gallons daily, 

 and quickly gave out. Reasoning that this oil had been 

 produced by the destructive distillation of coal at a low 

 temperature, though ignorant of Lord Dundonald's work, 

 he conceived the idea of producing a similar result artificially. 

 Many experiments showed the Boghead or Torbanehill gas- 

 coal, in West Lothian, to be the most suitable for his pur- 

 pose, and the celebrated Bathgate works were soon founded. 

 Lamp oil was the principal product, but lubricating oils 

 and solid paraffin were also produced. Markets were created 

 for the products, suitable lamps introduced, and " paraffin 

 oil," as it was called, rapidly became the source of light 

 throughout the Kingdom. 



The success of the manufacture led to the erection of 

 a number of works in Britain and on the Continent, some 

 of the latter importing the Torbanehill coal for distillation. 

 Factories were also started in America to treat the native 

 coals. When petroleum began to be produced in quantity 

 from the springs in Pennsylvania in 1859, these factories 

 were ready to be utilised for its refinement, and led to the 

 rapid development of the American petroleum industry, 

 which soon became a formidable rival to the Scottish 

 manufacture. 



In 1862 the supply of Torbanehill gas-coal, which had 

 ^^.elded about one hundred and twenty gallons of crude 

 oil to the ton, began to fail, and recourse was had to 

 bituminous shale, which yielded from thirty to forty-five 

 gallons only. Competition with .\merican oil then began 

 to be seriously felt, and in 1873 oils from Russia and the 

 East commenced to be largely imported. Ammonium 

 sulphate, a by-product of the process, had, however, begun 

 to be used in quantity, and was supplanting Peruvian 

 guano as a nitrogenous manure. But in 1890 its price fell 

 rapidly in consequence of the importation of nitrate of 

 soda. 



This long series of checks necessitated constant improve- 

 ments in processes, with the result that at the present time 

 treatment of a shale yielding twenty gallons of oil to the 

 ton is profitable, while the yield of ammonium sulphate 

 has increased from sixteen to sixty pounds per ton. 



The survival of this important home industry has 

 undoubtedly maintained the light of the people at about 

 half what it would otherwise have risen to, and paraffin 

 oil is to-day considerably cheaper in England than it is 

 in the oil-refining districts of America. 



The process as now carried out comprises two main 

 divisions. In the first, the shale is distilled in vertical 

 retorts, into which it is delivered at the top, descending 

 slowly, with a gradual increase of temperature as the ash 

 is removed by mechanical means beneath. Steam is intro- 

 duced below, as well as the permanent gas which is produced 

 during the distillation, no other fuel being required. The 

 products of the distillation are ammonia liquor and " crude 

 oil," wliich collect in two layers in the receivers. In the 

 second division the crude oil is refined by alternate dis- 

 tillations with fractionation into the several products, 

 and separate treatments with oil of vitriol and caustic 

 soda. By the distillation of the crude oil " green naphtha " 

 is first produced, followed by " green oil " as the temperature 

 rises These are collected separately. The former is agitated 

 with acid and alkali, and redistilled with the production of 

 naphtha and motor spirit. The green oil is subjected to a 

 series of such operations by which it is separated into burning 

 or light oils, intermediate, and heavy oils. The two latter 

 series are cooled to remove the solid paraffin, and used for 

 gas enrichment, liquid fuel, and lubrication. 



Liquid fuel has a thermal value greater by fifty per cent, 

 than that of coal, and has the further advantage for naval 

 purposes of easy stowage and of smokelessness, which render 

 its complete triumph certain. 



