982 THORPE AND HOLMES: THE OCCURRENCE OF By T. E. THORPE, C.B., F.R.S., and JOHN HOLMES. BY the Act of 5 & 6 Vict., c. 93 (1842), manufacturers were permitted to use oil in making up spun or roll tobacco, and by the Act of 42 and 43 Vict., c. 21 (1879), the word ‘‘ oil ” is defined as meaning “ essential oil ” for the purpose of flavouring, and ‘‘ olive oil ” for ‘‘ the process of spinning and rolling up.” Prior to 1900, no legal prohibition existed as to the amount of “oil” which could be so used, but in that year it was found desirable to restrict the quantity which might be present in manufactured tobacco t o 4 per cent., and by 63 & 64 Vict., c. 35 (1 goo), i t was enacted that in calculating the proportion of oil, any fatty o r oily substance which may be naturally present in the tobacco is t o be included within the 4 per cent.Discussion with manufacturers prior to the introduction of thisPARAFFINS IN THE LEAF OF TOEACC‘O. 983 measure showed that it was necessary to obtain some definite know- ledge concerning L L the fatty or oily substance ” which was alleged to be present in the natural leaf of tobacco. It was surmised by some makers that tobacco leaf not only contained such substances, but that the quantity varied with the character of leaf, conditions of growth, season, &c. At the same time, no very precise information as t o the real nature of this so-called fatty or oily substance could be elicited, nor could auything relative to the subject be discovered in the already very extensive literature dealing with the natural history of tobacco.A rapid and sufficiently accurate method of ascertaining whether the provisons of the lam are complied with as regards oil consists in macerating a weighed quantity of the manufactured product with a definite volume of light petroleum, of boiling point not exceeding 60°, for about 18 hours at the ordinary temperature. An aliquot portion of the clear solution is evaporated and the residual extractive mat.ter is dried and weighed. This is then saponified with a solution of alcoholic potash and the equivalent amount of olive oil calculated from the saponification value. Direct experiments have shown that the whole of the added oil can in this may be readily estimated, and t h a t the results are not materially affected by the small amount of matter which the light petroleum may have extracted from the leaf.It was, however, desirable t o obtain accurate knowledge of the nature and amount of the substance or substances which light petrol- eum would extract from the natural leaf of tobacco. ,4ccordingly, quantities of the various kinds of leaf used by a number of the largest manufacturers in the United Kingdom in making spun or twist tobacco were procured for examination. The samples selected consisted of some 46 representative varieties of Kentucky and Virginian-grown tobaccos, and care was taken that they corresponded in all respects with the leaf as imported; in other words, it, was ensured that the tobacco was in the condition technically known as ‘‘ raw leaf.” The amount of matter extracted from tobacco by light petroleum a t the ordinary temperature is very small, even after prolonged macera- tion.I n the case of the American tobaccos above-named, i t varied from less than 0.5 up to about 2 per cent.; the average amount yielded by the 46 different varieties was 1.25 per cent. No glyceride, or anything in the nature of a vegetable oil or true fat, could be discovered in the extract. Hence the apprehensions of certain manufacturers t>hat their legal position might be prejudicially affected by the variable amount of fatty or oily matter occurring in the untreated leaf of tobacco had no foundation infact, since such substances are not naturally present in 3 x 2984 THORPE AND HOLMES: THE OCCURRENCE OF tobacco. Experience has, in fact, amply demonstrated that the limit of oil imposed by Parliament has proved more than suficient for the proper manufacture of spun tobacco.The matter extracted by light petroleum from tobacco constitutes a dark brown, viscous or semi-solid substance, I t is readily soluble in cold ether, carbon disulphide, chloroform, or carbon tetrachloride, but more sparingly so in absolute alcohol. On shaking with water, the aqueous solution is strongly alkaline, contains nitrogen, and gives the usual reactions for alkaloids with iodine, corrosive sublimate, and platinum tetrachloride. This alkaloid consists almost entirely of nicotine. It is present to the extent of about one-fifth of the weight of the extract. In addition, there is a small amount of wax, equal to about three-tenths of a per cent., on the original leaf, and, lastly, there are two solid hydrocarbons of the paraffin series, an account of which forms the subject of the present communication, I n order to isolate the paraffins, a quantity of the light petroleum extract obtained from several kilograms of Western Kentucky leaf, used mainly as ‘‘ fillers,” was dissolved in the minimum quantity of ethyl ether and the solution mixed with about six times its volume of ethyl alcohol (rectified spirit).The precipitate thus obtained was re- dissolved in hot alcohol, separated by cooling, and recrystallised from ether. It formed pearly, nacreous scales melting at 63*0-63.8’, and gave, on analysis, Carbon ....................... S4.9 per cent. Hydrogen .................. 14.7 99.6 - showing that i t was almost certainly a hydrocarbon, or mixture of hydrocarbons.That it was not a wax or solid fat was further established by boiling with standard solution of alcoholic potash. This was shown to have no action upon it, nor was the melting point of the substance at all changed. A second preparation, from another variety of tobacco used for ‘‘ wrappers,” and a third preparation from leaf employed for general purposes, gave very similar results on analysis, and the products had substantially the same melting point. The actual amount of the hydrocarbon present in the leaf seemed to be fairly constant, judging from the following results : (1) 34.92 grams of light petroleum extract obtained from 2.211 kilos. of Western Kentucky leaf gave 2.337 grams of hydrocarbon, or 0.10 per cent.on the original leaf. (2) 28.03 grams of extract from 1.3’75 kilos. of Henderson tobacco gave 1.757 grams of hydrocarbon, or 0.13 per cent, on the original leaf,PARAFFINS IN THE LEAF OF TOBACCO. 085 (3) 106.02 grams of extract from 7.084 kilos. of leaf used for general purposes gave 8.157 grams of hydrocarbon, equal to 0.11 per cent. on the original leaf. The amount of the hydrocarbon present in American tobacco leaf may be taken therefore as rather more than one-tenth per cent. Although the light petroleum employed in these extractions boiled completely below 60° and left no solid residue on evaporation, it was desirable to prove that the paraffins obtained, which conceivably might exert even at 60' sufficient vapour pressure to distil over with the more volatile hydrocarbons, were not actually present in the light petroleum employed.Accordingly, about a kilogram of leaf was treated in precisely the same way with a mixture of chloroform and ether. A white substance was thus obtained resembling in all respects that extracted by the light petroleum. It melted at 64-66', and was found on analysis to have the percentage composition : Carbon ...................... 85.0 per cent. Hydrogen .................. 14.6 ,, - 99.6 Systematic examination of the product thus obtained showed that i t was in reality a mixture. By repeated fractional crystallisation from ether it was eventually resolved into two solid hydrocarbons, which, by analysis and treatment with bromine, were recognised as paraffins.The first hydrocarbon was found to melt a t 6'7.8-6S*5O, and gave on analysis the following numbers : Carbon ........................ S5.1 per cent. Hydrogen .................. 14.S ,, 99.9 A solution in carbon tetrachloride was unaffected (N/lO) in the same .solvent, and the substance characters of a hydrocarbon of the CnH271+2 series. by bromine had all the A determination of the molecular weight by the boiling point method, according t o Beckmann, using ether as a solvent, gave values varying from 412 to 419, which agree fairly well with that demanded by the formula C,,H,, (mol. wt. 436). Indeed there can be little doubt that this hydrocarbon is identical with Krafft's hentviacontane, C31H64, which has the melting point 68.1' (Ber., 1882, 15, 1687).The second hydrocarbon, after repeated crystallisation from ether, in which it is markedly more soluble than the other, was found t o melt constantly at 59-3-59.89 On analysis, it yielded :986 THE OCCURRENCE OF PARAFFINS Carbon ........................ Hydrogen .................. IN THE LEAF OF TOBACCO. 84.9 per cent. 14.8 ?, 99.7 It was entirely unaffected by a solution of bromine (N/lO) in carbon tetrachloride, and was in other respects very similar in char- acter to the hydrocarbon just described. A determination of molecular weight by Beckmann’s method gave somewhat higher values (433-440) than those obtained in the case of the other hydrocarbon, but the results of the analysis and the melting point indicate that the second hydrocarbon is in all probability heptcc- coscme, C27H56, the melting point of which was found by ICrafft to be The two paraffins appear to he present in tobacco leaf in about equal amounts and in the aggregate, as already stated, to the extent of about one part in a thousand.We incline to the opinion that the substance obtained by Kissling (Ber., 1883, 16, 2432), and regarded by him as a wax, was in reality a mixture of the two paraffin hydrocarbons just described. Kissling, who extracted the material by means of ether, found after repeated recrystallisation from alcohol that it formed a snow-white mass of satiny lustre melting at 6 3 O , and gave on analysis numbers agreeing withthose required for the formula C,OH,,oO,(C = 83.0, H = 13.8,O = 3.2 per cent.). It was present in Kentucky tobacco to the extent of 0.18 per cent. I n the course of an investigation on the constituents of tobacco smoke, Kissling also found a wax-like substance, similar in appearance to the so-called ‘( tobacco wax,” melting a t 64*5*, but which seemed on analysis to be a hydrocarbon coGtaining C = 84-7-85.5 and H = 14.63--15.16 per cent. There can be little doubt that the substances extracted by Kissling are identical, and that they were mixtures of the paraffin hydro- carbons hentriacontane and heptacosane described in the present communication. As present in Kentucky and Virginia leaf, we found such mixtures had the following melting points : 59.5O (ZOC. cit.). Western leaf .................. 63-0-63*S0 ‘‘ Wrappers ” .................. 63.5-64.0 ‘ I Fillers” ..................... 63.7-65-0 numbers almost identical with those observed by Kissling. TIIE GOVERNMENT LABORATORY. I,ONDON.