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SCIENTIFIC NEWS. 



[Oct. 19, 1888. 



The discoveries of M. Moreau are not the only ones 

 which have been made in Tunisia in the last few years. 

 Those of Dr. Collignon have already been spoken of, 

 and in 1844 the Marquis de Nadaillac presented to 

 the Society of Anthropology numerous flint implements 

 found by his son (then a captain in the 101st Regiment 

 of the Line), in the neighbourhood of Cabes, several 

 of which present a type very similar to those just 

 described. They consist especially of arrow-heads, and, 

 judging from their number, it is probable that there 

 must have been a numerous population. There were 

 also found hatchets, or at least fragments from the 

 ancient bed of the Oued-Gabes, where they lie in a 

 stratum of sand humus, covering a bed of gypsum. We 

 may also cite a number of flints in the form of a crescent, 

 very small, but bearing traces of careful workmanship. 

 These crescents cannot have been for any use ; they 

 must have been amulets or votive stones deposited in 

 sepulchres. M. Rivett-Carnac announces that flints of 

 similar shapes have been found in the province of Banda, 

 in India, and others are known as coming from the 

 Caucasus. It is curious thus to find the same designs 

 recurring in all latitudes and in all parts of the globe. 



THE FORMATION OF PETROLEUM. 



THE hypothesis of an inorganic origin of petroleum, 

 advanced at one time by Professor Mendelejeff 

 and others, is at present scarcely taken into considera- 

 tion, whilst the question whether it has been derived 

 from plants or from animals, must still be regarded 

 as open. Both these have found their advocates down 

 to the present day. Whilst the geologists, especially 

 since Leopold Von Buch, assume the animal remains 

 of earlier geological epochs — especially those of fishes, 

 saurians, corallines, sepias, shell-fish, etc. — as the primary 

 material of petroleum, the adherents of the other theory 

 seek for the origin of these fossil hydro-carbons in the 

 plant-world of those ages. Both parties agree, both on 

 chemical and on geological grounds, that the formation 

 of petroleum must have ensued under high pressure, but 

 not at a very high temperature. 



In consequence of experiments on the decomposition 

 of animal fats, Herr C. Engler (Deutsche Chemische 

 Gesellschaft and Naturforscher) has made observations 

 which may serve as contributions to the theory of the 

 formation of petroleum from animal matter. 



By the distillation of 500 kilos, (about 1,000 lbs.) of 

 fish oil from the Menhaden (Clupea menhaden) a large 

 kind of herring caught off the east coast of North America, 

 at pressures from 4 to 10 atmospheres, and at tem- 

 peratures of 320 degs. to 340 degs. Cent., he obtained, 

 along with gases and a watery liquor, about 300 kilos., 

 or 60 per cent., of an oil which was resolved into three 

 main fractions, boiling respectively at 150 degs., between 

 150 degs. and 300 degs., and above 300 degs. Cent. The 

 portion boiling below 150 degs. Cent., consisted of a 

 mixture of non-saturated and saturated hydro-carbons. 

 Check experiments with the glycerides of oleic and 

 stearic acid (artificially prepared), as well as with these 

 fatty acids, alone gave analogous results. It may there- 

 fore be regarded as proved that animal fats under strong 

 pressure are capable of conversion into hydrocarbons, 

 as it is also the case with vegetable fats. 



But though the conditions of the formation of petro- 

 leum from vegetable and animal matter may be regarded 

 as identical, Engler points out certain facts which are 



strongly in favour of the latter source. There is, above 

 all, the absence of any considerable deposits of plant 

 remains in connection with oil-regions, and inversely, 

 the absence of any abundant discoveries of petroleum 

 among coal-beds. On the other hand, where oil is 

 found in a primary deposit, animal remains can be 

 regularly pointed out. Thus in the shelly limestone 

 (inuschelkalk), in the Carpathian fish shales, and in 

 coral reefs, the occurrence of petroleum has been 

 observed. Particularly interesting are the orthoceratites 

 in the Trenton limestone at Packenham, in Canada, 

 whose former living-cells sometimes contain several 

 ounces of petroleum. Bituminous rocks display, as a 

 rule, considerable quantities of animal remains. 



The absence of nitrogen and its compounds in 

 petroleum seems at first sight striking, and not in favour 

 of their formation from animal matter. But the same 

 fact might with almost equal justice be urged against 

 their vegetable origin ; for the remains of plants con- 

 tain considerable quantities of nitrogen, as is proved by 

 the extraction of ammonia from coal on a commercial 

 scale. But, even disregarding the circumstance that 

 nitrogenous compounds occur in many petroleums, we 

 must consider the very unequal stability of the non- 

 nitrogenous oils and of the nitrogenous muscular sub- 

 stance of the animal body. Engler recalls many obser- 

 vations on the formation of adipocire, " fat-wax," a 

 product of the transformation of the fats during the 

 decay of animal remains. This substance, which often 

 contains as much as 98 per cent, of fatty acids, is still 

 found even when the nitrogenous matter and the very 

 bones have disappeared. Thus in the accumulated 

 animal remains of the primitive world the decomposition 

 may have proceeded in two main phases. The nitro- 

 genous compounds were decomposed, the nitrogen 

 escaped either in the free state, or in that of ammonia 

 and other compounds. The fat remained behind or was 

 transferred to secondary localities, where it was finally 

 converted into petroleum. 



The absence of carbonaceous residues in mineral oils 

 must be interpreted as militating against a vegetable 

 rather than an animal origin. The poverty of cellulose 

 in hydrogen, in case of a decomposition at a low tem- 

 perature (whereby the formation of carbonic acids is 

 trifling, as compared with the formation of water), must 

 necessarily involve a more abundant liberation of carbon. 

 It is different in animal fats or in the fatty acids thence 

 resulting. If in these all the oxygen with an equivalent 

 proportion of hydrogen be eliminated as water, there 

 remains carbon and hydrogen in an approximate propor- 

 tion of 87 per cent, carbon and 13 per cent, hydrogen. 

 But this is, as Engler shows, very near the general 

 composition of crude mineral oils. His experiments 

 have also shown that fats and fatty acids under pressure 

 in a sealed tube are often resolved into gases and volatile 

 hydrocarbons without any important separation of car- 

 bonaceous residues. Engler, therefore, maintains that 

 petroleum is essentially of animal origin, especially as 

 the ancient marine flora was very small in quantity in 

 comparison with its fauna. 



— «^ 



The Buffon Centenary. — At a commemoration of the 

 hundredth anniversary of the death of Buffon, discourses 

 were pronounced by M. Guillaume, a connection of the 

 Buffon family, and by M Gtan^id^er, ?n behalf of the 

 Academy of Sciences. 



