borhood of the wells. In the oil regions and their vicinities of North America and Baku, the gases issue from the ground, frequently without petroleum, in such quantities that they can be used for technical purposes, and hence deserve special consideration. The natural earth gases issuing from the petroleum wells of Pennsylvania have been examined by Fouqué, Ronalds, Lefèbre, Sadtler, Ford, Hay, Fulton and others, those of New York by Wurtz, of the peninsula Apscheron (Baku), which, according to Abich, have a temperature of 69° F., by Schmidt, and those of the peninsulas Kertsch and Taman (Asow Sea) by Bunsen. All these investigators found a decided preponderance of methane and its nearest homologues in them. Further details are given in the following table, which might be still more enlarged: The analyses 13 to 16 refer to the same gas well, but the samples were taken at different periods (October 28 and 29, November 24, and December 4, 1884). Analyses 17 and 18 also refer to the same well at different periods (October 18 and 25, 1884). These analyses, showing remarkable changes in the composition of the gases, are in many respects of great interest; while the one series (13 to 16) shows in the course of time with a steady decrease in methane, a steady increase in ethane and hydrogen, in the other series the reverse is partially the case, the only agreement which can be recognized being that the quantities of methane and ethane are in a reverse ratio. The natural gases from Murraysville, Speechley, and Fredonia II have recently been analyzed by C. Phillips', who took the samples directly from the wells he examined 1. Gas of the Fredonia Co. -and found: N. O. H Cn Hm. C. H 21.83 23.36 23.48 23.18 22.93 25.06 78.17 76.64 76.52 76.82 77.07 74.94 Ammonia as well as carbonic oxide could not be established. 1 Annual Report of the Geological Survey of Penna. Whether nitrogen was present in a free or fixed state was not closly examined into. Its determination was effected by conducting the gas over red-hot copper oxide. That the large amount of nitrogen cannot be referred to atmospheric air (somewhat decomposed) is proved by the small quantities of carbonic oxide and by the presence of oxygen in traces only. With this agree also analyses I, II, 16 and 19 of the table previously given. Phillips mentions expressly that ammonia is not present in the natural gases examined by him. Engler examined the following natural gases of Pechelbronn (Alsace). I. The salt-water gas No. 1., which continuously issues from the ground together with salt water and is used for heating purposes in the laboratory; II. the salt water gas No. 2, and III. the gas which issues together with the oil from the wells. In the salt water gas No. 1 (I) free oxygen and hydrogen were searched for in vain. Engler supposes that the oxygen is derived from the air, which was originally in contact with the oil and gradually yielded its oxygen to the latter, so that only nitrogen remained behind. In II. and III. the oxygen and nitrogen were referred directly to atmospheric air. The high content of carbonic oxide in the Pechelbronn natural gas is remarkable, and, according to Engler, supports the hypothesis according to which petroleum has been formed by dry distillation, and is opposed to the supposition of a process of fermentation. Natural gas has for a long time been used in various localities for technical purposes; for the longest time perhaps in the district Tsien-Luon-Tsing, China, where, according to Imbert, it issues together with the brine from wells up to 3000 feet deep, in such quantities that it is used not only for illuminating purposes, but also for evaporating the brine. Baron von Richthofen states that in the province Sz'-tschwan the gas is at the present time used for the same purposes. Such exhalations of gas have been frequently observed to accompany the occurrence of salt; thus as early as 1786 the gas was used for illuminating the salt-mine Ludovica at Szlatina (Hungary). The gas is, however, most extensively used in the eastern parts of this country, especially in Pittsburgh, where it issues in enormous quantities from many wells. It is chiefly used for fuel and but seldom for illuminating purposes, its illuminating power being somewhat less than that of ordinary illuminating gas. By experiments on a large scale it was found that in firing boilers 83 per cent. of the theoretical heating effect is utilized (of the best Pittsburgh coal 64 per cent.), 100 liters of gas weigh 64.86 grammes and possess about 790,000 units of heat, hence about seven times as many as the Siemens gas. A committee of the "Engineers' Society West Pennsylvania' determined by direct boiler experiments the evaporating power of best Pittsburgh coal as 9 kilogrammes (19.8 lbs.) of water, and that of natural gas as 20.31 kilogrammes (44.68 lbs.) referred to 1 kilogramme (2.2 lbs.) of fuel. Hence the calorific value of natural gas is 3.36 times greater than that of coal. |