PART I. Examination of Ben Davis Apples.

The variety of apple first examined was that known as the Ben Davis, as this was available in considerable quantity, and as the odorous constituents appear to be contained chiefly in the outer skin or rind of the fruit, only the parings were employed. The apples had been stored in a cellar without refrigeration, and at the time of distillation, in the latter part of October, had developed considerable odour. They were pared by means of a machine, which was so adjusted as to completely remove the rind with only a very small portion of the white substance of the apple, and without removing the core, so that any admixture of seeds was carefully excluded. In order to avoid any possibility of fermentation or loss of volatile substances the fresh parings were brought immediately into a still, and, without any further addition of water, subjected to distillation in a current of steam. The total amount of parings employed from the above-mentioned variety of apples was about 161 kg., representing approximately 805 kg, of the entire fruit. The amount of aqueous distillate collected was 163 litres. This distillate was somewhat opalescent, and the first portions separated some oily drops, but on keeping for a few days it became perfectly clear, with the separation of a little solid material on the sides of the glass vessels containing it. The liquid possessed in a high degree the pleasant, characteristic odour of fresh, ripe apples, and even the first portions of the distillate were perfectly neutral to test-paper. After decanting the aqueous liquid, the above-mentioned solid material was dissolved by means of ether, the ethereal solution dried with anhydrous sodium sulphate, and the solvent evaporated. A small amount (0'04 grm.) of a colourless, flocculent substance was thus obtained, which was soluble in hot alcohol, but separated for the most part on cooling. When collected on a filter, and dried on a porous plate, it formed thin, satiny laminæ, which were not altered by contact with either conc. nitric or sulphuric acid. The substance melted quite sharply at 63° and was probably slightly impure triacontane, CH.2, which stated to melt at 65:6°. Concentration of the Distillate. Identification of Furfural and Acetaldehyde.

is

A large portion of the original aqueous distillate, amounting to 106 litres and representing 107 kg. of apple parings, was repeatedly cohobated in a current of steam, whereby the odorous substances were eventually concentrated in a volume of about one litre, the nearly odourless liquids remaining from this treatment being reserved for further examination. The concentrated distillate, which was practically neutral and contained some globules of colourless oil floating on the surface, was first subjected to some special tests. It gave no coloration with ferric chloride, indicating the absence of phenolic substances, but rapidly reduced an ammoniacal solution of silver oxide in the cold, producing a metallic mirror, and also

gave an immediate red coloration with sensitised Schiff's reagent, which was evidence of the presence of an aldehyde (Mulliken, "Identification of Pure Organic Compounds,” 1905, i., 15. A few drops of the liquid gave with aniline and hydrochloric acid the bright red coloration characteristic of furfural, the latter having doubtless been produced in the process of distillation. When tested for formaldehyde by means of phenylhydrazine hydrochloride a perfectly negative result was obtained (Z. Nahr. Genussm., 1902, V., 353, and J. Assoc. Official Agr. Chemists, Methods of Analysis, 1916, p. 147). On the other hand, the 'distillate gave the specific reaction for acetaldehyde, which consists in adding to a little of the liquid in a test-tube one or two drops of a solution of dimethylamine (33 per cent) and subsequently about 5 drops of a freshly prepared i per cent aqueous solution of sodium nitroprusside, when a beautiful indigo-blue colour is produced, soon changing to brown or yellow. Rimini (Annali Farmacoterapia e Ch., 1898, p. 249; Chem. Centr., 1898, Bd. II., p. 277) has shown that the reaction for acetaldehyde as obtained by Simon (Compt. Rend., 1897, CXXV. 1105; J. Chem. Soc., 1898, Ixxiv., II., 315) with trimethylamine was due to the presence in the latter of dimethylamine, and that it is given by all secondary bases of the aliphatic series or by ring compounds which have completely lost their aromatic character by hydrogenation. We have found that the abovementioned blue coloration is readily obtained with a solution of one part by weight of acetaldehyde in 10,000 parts of water, but that it is not produced by formaldehyde, the higher fatty aldehydes, such as n-heptylic aldehyde, or by aliphatic terpene aldehydes, such as citral, which gives only a reddish colour. Further confirmation of the presence of acetaldehyde, and evidence of its Occurrence as an emanation from ripe apples will subsequently be described.

Hydrolysis of the Esters Contained in the Concentrated Distillate. Identification of Amyl Alcohol and Formic and Caprylic Acids.

The previously mentioned concentrated distillate, amounting to about one litre, was brought into a flask provided with an inverted condenser, 25 grms. of pure sodium hydroxide added, and the mixture kept in active ebullition for 2 hours. During this operation the liquid acquired a deep yellow colour, and a small amount of material separated, which evidently consisted of the socalled aldehyde resin. After cooling, the contents of the flask were distilled in a current of steam, and about 300 cc. of liquid was collected. This liquid, which gave no reaction for aldehyde, possessed a pleasant odour, and after a short time an appreciable amount of yellowish, oily drops separated on the surface. It was extracted five times with pure, aldehyde-free ether, and the neutral aqueous liquid then reserved in order to test for the presence of methyl alcohol, as subsequently described.

(It is known that acetaldehyde when heated with a caustic alkali is chiefly converted into the socalled aldehyde resin, and that small amounts of formic and acetic acids are also produced, together with some odorous substances which may be extracted from the distilled liquid by means of ether. The formation of these products has been duly considered when necessary in the

present investigation in order to exclude any incorrect deductions).

The above-mentioned ethereal liquids were united, dried with anhydrous sodium sulphate, and the greater part of the ether removed by distillation, the residual liquid being then brought into a small, tared flask and allowed to evaporate spontaneously until the odour of ether, had disappeared. A yellowish oily liquid was thus obtained, which had a distinct odour of amyl alcohol, and produced the characteristic irritating effect of the latter on the throat when inhaled. The amount of this liquid was o7063 grms., which represented o 00065 per cent of the weight of apple parings employed. It was brought into a strong flask provided with a tightly-fitting glass stopper, 25 cc. of a chromic acid mixture (J. prakt. Chem., 1892, xlv., 599) added, and the whole heated for 15 minutes on a water-bath at a temperature of about 90° with occasional agitation. The flask was then cooled, the contents diluted with water, transferred to a separatory funnel, and the acid liquid extracted five times with pure, aldehydefree ether. The united ethereal liquids, after being washed with a little water, were extracted four times successively with 25 CC. of a 5 per cent solution of barium hydroxide. The total alkaline liquid was treated with carbon dioxide for the removal of the excess of baryta, and, after filtration, the neutral liquid was concentrated to a small volume.

(To be continued.)

CHEMICAL NOTICES FROM FOREIGN

SOURCES.

Journal de Pharmacie et de Chimie. Vol. xxii., 7th Series, No. 4, August 16, 1920. ACTION OF HYDROCYANIC ACID ON GLUCOSE. KILIANI'S REACTION.—MM. J. Bougault and J. Perrier. According to Emil Fischer (Liebig's Annalen, 1892, cclxx., 64), the synthesis of oxyacids by the action of hydrocyanic acids on aldehydes is due to the work of Winkler (about 1830). This reaction has been applied to the sugars (glucose, &c.), by Kiliani (Ber., 1885, xviii, 3168), by whose name the reaction is known, although it was a French chemist, Schützenberger (Bull. Soc. Chim. [2], 1881, xxxvi., 144), who first showed that inverted sugars, when subjected to the action of hydrocyanic acid and water, give rise to acids containing seven atoms of carbon, according to the equation—

CH0%+CNH+2H,O=C,H,O,CO,NH,

The above authors have further investigated this reaction, and have discovered that alkalinity and acidity play an important part in the success of the operation. In a very faintly acid solution the reaction does not take place, likewise it fails in neutral solution. But it is difficult to lay this latter point down definitely as it is very difficult to obtain an exactly neutral solution, the alkalinity of the glass vessel being sufficient to act as a catalyst. From the above remarks, the authors infer that it was a cyanide and not hydrocyanic acid which plays the active role in the reaction. By writing the equation in the following manner CH0+CNK+2H,O=C,H,O.CO,K+NH,

13

these facts can be stated; it can be seen that the quantity of alkali taking part in the reaction as cyanide reappears in an equivalent quantity as ammonia on the right-hand side of the equation. This ammonia gives rise to a further quantity of cyanide, which combines as before with a fresh quantity of glucose, and so on.

NOTES.

AT the Machine Tool Trades Exhibition to be held at Olympia in September, a great Convention will be held under the joint auspices of the Home Office and the British Industrial "Safety First" Association. There will be two sessions, at which papers of absorbing interest will be discussed.

ALCOHOL FUEL PATENTS.-Warning to Investors. The Empire Motor Fuels Committee of the Imperial Motor Transport Council has recently been considering the abnormal and unhealthy activity shown by pseudo-inventors in respect of alcohol motor fuels and mixtures containing alcohol. Shortly before the House rose, Mr. E. Manville, M.P., at the request of the Empire Motor Fuels Committee, addressed the following question to the President of the Board of Trade: "If the Patent Office will pay special attention to the number of applications for letters patent in respect of admixtures of such bodies as alcohol, ether, kerosene, benzol, and toluol, as motor fuels, in which applications no element of novelty, discovery, or invention appears to be disclosed; and if he will give instructions to the Patent Office to be especially careful not to hamper or prejudice the production or utilisation of new motor fuels by the creation of ground for litigation in respect of alleged master patents." Sir Robert Horne's reply was that "Full and proper consideration will be given to all applications for patents in respect of inventions relating to new motor fuels before the patent is granted. The Comptroller of the Patent Office in considering what is a proper subject of a patent, is, of course, bound by the provisions of the Patents and Designs Act in accordance with which he must act." It is felt by the Empire Motor Fuels Committee that great damage may be done to the prospect of early production and marketing of new motor fuels if disregard is shown by the Patent Office for the known miscibility within various limits of alcohol, benzol, petrol, and other hydro-carbons and carbohydrates, and the Committee wishes to give warning to the investing public that any claim to a master patent should in any conceivable circumstances be viewed with the maximum of doubt. The Committee feels it is regrettable in the public interests that the Patent Office should be allowing patents to be granted for mixtures which every chemist knows can be employed as fuels and which every engineer knows are more or less applicable in existing engines or in engines slightly adapted in order to suit such mixtures.

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