It might be noticed

Comparison with Russian kerosines.

that there is a close agreement, especially in the earlier portions, between the specific gravities of the several fractions obtained during the fractional distillation of Mr. Oldham's sample and the results obtained by Mr. Boverton Redwood (Jour. Soc. Chem. Ind., Vol. IV, p. 76) from several samples of Russian kerosine. I append these results in parallel columns for comparison

This agreement in the densities of the distillates might at first seem discordant with the flashing points; but it appears from the researches of Beilstein, Schützenberger and others that the higher specific gravity of Russian kerosines, when compared with American and other commercial oils, is due to the large quantities of isomers of the olefine series (naphthenes) in the Caucasian products, whilst the various members of the isologous series of paraffins which predominate in the American petroleum have, for corresponding boiling points, lower specific gravities. The conversion of the latter into the former has been shown by Thorpe and Young to be the result of the process termed "cracking," and this fact must be taken into consideration in comparing the results of the fractional distillation of crude oils and those of commercial oils, which, like most American samples, have been "cracked." The agreement, therefore, of the specific gravities of the oil from the Sheráni country and that of marketable Russian kerosines does not necessarily indicate a corresponding commercial value.

Modification of the

still.

In the fractional distillation of mineral oils the loss commonly amounts to between 3 and 5 per cent., which seems due to the escape of hydrocarbons between the neck of the retort and the condenser. Unless the flashing point of the oil is very low and the temperature of the laboratory high, there can be no appreciable escape at the lower end of the condenser,-practically none after the first fraction.

In order to prevent the escape at the junction of the neck of the retort and the condenser, I have used a thick india-rubber tube which fits around the neck of the retort and tightly into the condenser. This allows of a considerable latitude of oscillatory movement and at the same time preserves a vapourtight joint.

The only objections which I can see to this simple contrivance are, (1) the action of the hydrocarbons on the caoutchouc and (2) the effect of the high temperature on the rubber.

In consideration of each of these I have made a series of experiments which seem to show that these objections are of little practical concern.

Action of kerosine on india-rubber.

(1). To test the action of the oil on the caoutchouc, a piece of the red rubber, weighing 77282 grammes, was used. Its specific gravity, both by weighing in water and by floating in a solution of salt, was found, as the average of closely agreeing results, to be 105. It was then immersed for twenty-four hours in the first distillate obtained from petroleum distilling below 430°F., and having a specific gravity of 7803 at 60° F. (7727° at 79° F.). On cleaning with weak alcohol the rubber was found to have increased in weight by the absorption of the liquid hydrocarbons to 21 370 grammes, indicating an absorption of nearly double its own weight. It had increased considerably in bulk, the specific gravity being reduced to '840, so that it easily floated on water. The residue of the liquid showed no change in its density (774 at 76° F.). There was nothing, therefore, dissolved from the rubber which might affect the characters of the oil.

water.

After three months' exposure to the open air at a temperature ranging between 75° and 85° F. the rubber became reduced to 13'563 grammes and would still float in On raising the temperature to 2c0° F. for four hours its weight quickly descended, although the vessel in which it was contained was kept filled with the vapours given off, and the specific gravity was so reduced that it again sank in

water.

I do not see that the distillates from the petroleum could in any way be affected by solution of the rubber; and at a high temperature, exposed only to vapours, the absorption must, on account of the small surface presented and that under pressure be inappreciable.

Pure caoutchouc begins to melt at 248° F. Its melting point is considerably raised by vulcanization and the introduction of mineral colouring matter, by which means the caoutchouc is reduced sometimes to 50 per cent. of the rubber.

Effect of high temperature.

By enveloping the joint with cotton-wool and packing in a thermometer, I found the temperature throughout the distillation never exceeded 270° F., and by removing the joint further from the retort the temperature can be kept still lower. There is thus no fear of the results being affected by the melting of the caoutchouc. The rubber may be found to have just adhered slightly to the glass, but shows no other signs of change. I have, consequently, considered it unnecessary to ascertain if any isoprene or caoutchene had been given off. These substances, moreover, would have all been lost during the vulcanization of the caoutchouc; and, if there was a possibility of the rubber giving off any vapours at such a low temperature, they would have found their way into the open air rather than into the condenser. Certainly, such would have no appreciable effect upon the distillates. The simplicity of the arrangement is the only apparent reason left for supposing its adoption must be accompanied by some source of error.

With the small quantity of material at my disposal, it was impossible to attempt a complete proximate analysis of the Sheráni oil. From the researches of a large number of workers, most petroleums appear to be composed principally of a complex mixture of

Hydrocarbons in the crude oil.

homologues ard isomers of the paraffin series (Cn Han+), and Warren1 was able, in 1868, by means of an improvement in the method of fractional distillation, to add to the results obtained by Pelouze and Cahours by showing the existence also in the Pennsylvanian oil of homologues of the series CnH2n. Following these, which have been found in varying proportions in all crude petroleums, comes the interesting question of the presence of members of the benzene series (CnH2n—6).

In 1856, Warren de la Rue and Hugo Müller announced the discovery in Rangoon tar of the hydrocarbons benzene (CH), toluene (C,Hg), xylene (CgH10) and cumene (C,H12).*

In 1860, Bussenius and Eisenstuck found xylene in a sample of Hanoverian petroleum.

In the same year, Pebal and Freund obtained five homologues of this series in naphtha from Galicia."

In 1863, J. Pelouze and A. Cahours, whilst recording the occurrence in Pennsylvanian petroleum of homologues of the marsh gas series from C H10 to C15 H2, besides possibly higher solid paraffins, distinctly denied the presence of the benzols.

In 1865, Schoriemmer, in the first of an exhaustive series of researches on the hydrocarbons of the series Cn H2n+g, showed the existence in Canadian rock-oil of the benzols.9

In 1867, the results of de la Rue and Müller were confirmed by the detection in Rangoon tar of xylene and isocumene by Warren and Storer.10

12

In 1876, Beilstein and Kurbatow obtained additive products of benzene (hexhydrobenzene, C. H12, &c.) in Caucasian petroleum;11 whilst in 1878, and again in 1882, Markownikoff and Oglobini obtained isomerides of this series in oil from the same locality. These results were confirmed by Markownikoff in 1886, when he pointed out the existence of the naphthenes already referred to13 (ante, p. 87). Many of the other results have also been confirmed by different authors, notably the occurrence of the aromatic hydrocarbons in Galician CnH2n-6 in the Baluchis- petroleum by Lachowicz and by Pawlewski.

Presence of the series

tan oil.

In examining the Sherani oil for aromatic hydrocarbons,

"Hydrocarbons of Pennsylvanian petroleum."-Amer. Journ. Sci., ser. 2, vol. xlv, (1868), p. 262.

2" On a process of fractional condensation applicable to the separation of bodies having small differences in their boiling points."-Amer. Journ. Sci., ser. 2, vol. xxxix (1865), p.

327.

"Recherches sur les pétroles d'Amérique."-Comptes Rendus, vol. Ivi (1863), p. 505,

and vol. lvii (1863), p. 62.

Proc. Royal Soc., vol. viii (1856), p. 225.

5 Ann. Chem. u. Pharm., vol. cxiii (1860), p. 151.

6 Ibid., vol. cxv (1860), p. 19.

7 Comptes Rendus, vol. lvii (1863), p. 62.

Loc. cit., p. 69.

Proc. Royal Soc., vol. xiv (1865), p. 168 (foot-note).

10 Amer. Journ. Sci., ser. 2, vol. xliii (1867), p. 251. (Abstract of paper from Mem. Amer. Acad., new ser, vol. ix, P. 208.

"Ber. Deutsch. Chem. Ges., vol. xfii, p. 1818 and vol. xiv, p. 1620.

I have followed the method used and described by Schorlemmer in the classic researches already quoted.1

A portion was distilled below 300° F., and the distillate treated with fuming nitric acid to produce the nitro-substitution products (Mitscherlich's 'nitrobenzides ") which were separated after dilution with water. When exposed to the action of nascent hydrogen the nitro-benzene (taking the initial term in the series) was reduced to the corresponding amidobenzene (C,H,NH,, or aniline), and the solution then distilled with caustic potash. The aqueous distillate gave the characteristic violet colour when treated with an alkaline hypochlorite. In this manner I treated three portions of the oil, but one of the re-actions failed on account of the acid being mistaken. In the other two the characteristic re-actions of the benzene series were most decided.

Salts dissolved in the

water accompanying the crude on.

I have made a careful qualitative examination of the small quantity of water which separated at the bottom of the sample of oil. The water gave distinctly acid re-actions with litmus, and I found that both sulphates and sulphides existed in combination with lime and traces of iron and magnesia. The lime was obtained as a sulphate in minute, characteristic, monoclinic combinations and twins of gypsum, on slow evaporation of the water under the microscope.$

A portion of the water was treated with a drop of nitric acid, ammonic chloride and ammonia, filtered, concentrated, and a drop of the filtrate placed on a slide. A drop of sodic phosphate solution and ammonia was placed near the first drop, and the two, after raising the temperature, were connected with a fine capillary tube of glass, when the formation of rhombic combinations of ammonic magnesic phosphate was observed under the microscope.*

I was unable to obtain definite re-actions for chlorides, nitrates or sulphides In describing the Khatan oil-fields, Mr. R. A. Townsend, in a previous volume of the Records, mentions the occurrence of sulphuretted hydrogen, sulphurous acid, sulphur, gypsum and pyrites in connection with the oil springs."

Previous examinations of Baluchistan oil.

Amongst the analyses made in the laboratory of the Geological Survey, I find two accounts of Baluchistan oil which have not as yet been published.

In 1886, the late Mr. E. J. Jones determined the specific gravity of a sample of "crude petroleum from Khatan, Beluchistan." He says that it "floats on water, while with the hydrometer it gives a specific gravity of 1005, the same hydrometer giving a specific gravity of o'995 with water at a temperature of 86° F."

In June, 1887, Mr. F. R. Mallet gives the following results of his examination of crude petroleum from Khatan, Beluchistan :

"Dark brown colour; thick and ropy consistency; specific gravity, 1'008 at 88° (or 1019 at 60° F.)

'Loc. cit., p. 168.

2 Pogg. Ann., vol. xxxi, p. 625.

Behrens' test, "Mikrochemische Methoden zur Mineralanalyse."—Verslagen en Mede. deelingen d. k. Akad. van Wetensch. Amsterdam, 1881, p. 47.

Behrens, loc. cit., p. 55.

Rec. Geol. Surv. Ind., vol. xix (1886), pp. 208 and 210.

"Owing to the water contained in the crude petroleum, the latter foams up and pours into the condenser unless the heat is properly managed. When heated very gently for a sufficient length of time, the water distills over first, after which the temperature may be raised and the oil distilled without risk of foaming.

66

The following results were obtained on partial distillation of the oil:

Pitch brittle and pulverizable at 85° F., although not quite so easily as No. 1.