All these reactions show that the phenol occurs in the free state in the cones of this plant. In the same manner I treated the acicular leaves, and portions of the stem separately, both being previously cut up into small pieces, and from both I obtained phenol.
I have ascertained the relative amount of phenol in each part of the plant operated upon; by heating the stem with water at 80° C., and filtering, and repeating this operation until the aqueous filtrate gave no violet color with ferric chloride and no white precipitate with bromine water.
I found various quantities according to the age of the stem. The older portions yielding as much as 0.1021 per cent, while the young portions only gave 0.0654 per cent. The leaves yielding according to their age, 0.0936 and 0.0315 per cent.; and the cones also gave varying amounts, according to their maturity, the amounts varying between 0.0774 and 0.0293.
Two methods were used in the quantitative estimation of the amount of phenol. The first was the new volumetric method of M. Chandelon (Bulletin de la Societe Chemique de Paris, July 20, 1882; and Deutsch-Americanishe Apotheker Zeitung, vol. iii., No. 12, September 1, 1882), which I have found to be very satisfactory. The process depends on the precipitation of phenol by a dilute aqueous solution of bromine as tribromophenol. The second method was to extract, as already staled, a known weight of each part of the plant with water, until the last extract gives no violet color with ferric chloride, and no white precipitate with the bromine test (which is capable of detecting in a solution the 1/60000 part of phenol). The aqueous extract is at this point evaporated, then ether is added, and finally the ethereal solution is allowed to evaporate. The residue (phenol) is weighed directly, and from this the percentage can be ascertained. By this method of extraction, the oil of turpentine, resins, etc., contained in Pinus sylvestris do not pass into solution, because they are insoluble in water, even when boiling; what passes into solution besides phenol is a little tannin, which is practically insoluble in ether.
From this investigation it will be seen that phenol exists in various proportions in the free state in the leaves, stem, and cones of Pinus sylvestris, and as this compound is a product in the distillation of coal, and as geologists have to a certain extent direct evidence that the flora of the Carboniferous epoch was essentially crytogamous, the only phænogamous plants which constituted any feature in "the coal forests" being the coniferæ, and as coal is the fossil remains of that gigantic flora which contained phenol, I think my discovery of phenol in the coniferæ of the present day further supports, from a chemical point of view, the views of geologists that the coniferæ existed so far back in the world's history as the Carboniferous age.
I think this discovery also supports the theory that the origin of petroleum in nature is produced by moderate heat on coal or similar matter of a vegetable origin. For we know from the researches of Freund and Pebal (Ann. Chem. Pharm., cxv. 19), that petroleum contains phenol and its homologues, and as I have found this organic compound in the coniferæ of to-day, it is probable that petroleum in certain areas has been produced from the conifers and the flora generally of some primæval forests. It is stated by numerous chemists that "petroleum almost always contains solid paraffin" and similar hydrocarbons. Professors Schorlemmer and Thorpe have found heptane in Pinus, which heptane yielded primary heptyl-alcohol, and methyl-pentyl-carbinol, exactly as the heptane obtained from petroleum does (Annalen de Chemie, ccxvii., 139, and clxxxviii., 249; and Berichte der Deutschen Chemischen Gesellschaft, viii., 1649); and, further, petroleum contains a large number of hydrocarbons which are found in coal. Again, Mendelejeff, Beilstein, and others (Bulletin de la Societe Chemique de Paris, No. 1, July 5, 1883), have found hydrocarbons of the—
CnH2n2+, CnH2n-6,
also hydrocarbons of the CnH2n series in the petroleum of Baku, American petroleum containing similar hydrocarbons.
I think all these facts give very great weight to the theory that petroleum is of organic origin.
On the other hand, Berthelot, from his synthetic production of hydrocarbons, believes that the interior of the globe contains alkaline metals in the free state, which yield acetylides in the presence of carbonic anhydride, which are decomposed into acetylene by aqueous vapor. But it has been already proved that acetylene may be polymerized, so as to produce aromatic carbides, or the derivatives of marsh gas, by the absorption of hydrogen. Berthelot's view, therefore, is too imaginative; for the presence of free alkaline metals in the earth's interior is an unproved and very improbable hypothesis. Byasson states that petroleum is formed by the action of water, carbonic anhydride, and sulphureted hydrogen upon incandescent iron. Mendelejeff thinks it is formed by the action of aqueous vapor upon carbides of iron; and in his article, "Petroleum, the Light of the Poor" (in this month's—February—number of Good Words), Sir Lyon Playfair, K.C.B., F.R.S., etc., holds opinions similar to those of Mendelejeff.