1168 THE COLLIERY GUARDIAN. June 22, 1917. It is an advantage to carry out a few distillation tests to secure sufficient of each fraction to test in comparison with well-recognised products. Thus, the several curves may be com]) ar eel with those shown in fig. 10, which represent distillation curves of (a) washed 90 per cent, benzol, (5) 50 per cent, benzol, (r) 90 per cent, toluol, and (d) solvent naphtha. The pro- ducts from the quantitative tests should agree fairly well with these curves. To estimate the proportion of pure products, a more elaborate procedure is necessary, and after several trials with methods advocated by various observers, the writer has found that an adaptation of the scheme described by Edwards* is well suited for this purpose. Details of a test carried out by the writer on these principles are given below :— In this test, 400 c.c. crude benzol (from the same store tank as the previous test) was distilled in two lots in a flask, fitted with a 12 bulb Young column, up to a temperature of 180 degs. Cent. : — Distillate = 340 c.c. (A); residue = 60 c.c. (B). (A) Re-distilled in same apparatus to 145 degs. Cent. : — Distillate = 314 c.c. (C) ; residue = 26 c.c. (D). (C) (1) Washed three times with sulphuric acid (1-84) using 5 per cent, by volume each time, and shaking for two, five, and five minutes respectively; (2) gently washed with water; (3) washed with caustic soda and water; (4) dried with calcium chloride. (E) Result: 290 c.c. washed and dried product; loss, 24 c.c., or 6 per cent, on original sample. (E) Fractionated in same apparatus: (1) up to 85 degs. Cent., 128 c.c. ; (2) 85 to 96 degs., 97 c.c. ; (3) 96 to 110-7 degs., 26 c.c.; (4) 110-7 to 125 degs., 26 c.c.; (5) residue, 13 c.c. (1) Refractionated to 80-2 degs., gave 33 c.c. “ first runnings,” 95 c.c. to No. 2. (3) Refractionated to 110-7 degs. gave 15 cc. to No. 2, 11 c.c. to No. 5. (4) Refractionated to 110-7 degs., gave 14 c.c. to No. 2, 12 c.c. to No. 5. No. 2 and No. 5, not refractionated, but augmented by the above distillates and residues, giving 33 c.c. first runnings; 221 c.c., No. 2, consisting of a mixture of benzene and toluene; 36 c.c., No. 5, consisting of a mixture of-toluene and xylene. The proportion of benzene and toluene in No. 2 is found by ascertaining the boiling point of the mixture in a boiling point apparatus fitted with a reflux con- denser, as shown in the original paper. This will range between 80-2 and 110-7 degs. Cent, the boiling points of benzene and toluene respectively. From the boiling point of the No. 2 fraction, which was found to be 82-9 degs. Cent., the proportions were read off from a curve constructed from data in the paper, showing 84 per cent, benzene, and 16 per cent, toluene, or, calculated on the volume of the mixture (221 c.c.), a proportion of 185-6 c.c. benzene and 35-4 c.c. toluene. On similar lines, No. 5 gave 26-5 c.c. toluene and 9-5 c.c. xylene. These two results totalled gave the following analysis:—33 c.c. first runnings, or 8-2 per cent, on original; 185-6 c.c. benzene, or 46-4 per cent, on original; 61-9 c.c. toluene, or 15'5 per cent, on original; 9-5 c.c. xylene, or 2-4 per cent, on original. 90 so Fig 10. TEMPERATURE — CEKT ° .go 90 /OO no 120 130 140 150 IGO 170 The two residues (B) and (D) were totalled and dis- tilled to 190 degs. Cent., giving 34 c.c. naphthas, or 8-5 per cent., and 52 c.c. creosote, or 13 per cent. The final analysis would thus be given as: —First runnings, 8-2 per cent.; benzene, 46-4; toluene, 15*5; xylene, 2-4; solvent and heavy naphtha, 8-5; creosote oil, 13; loss on washing, 6 per cent. It is often of importance to know the amount of carbon disulphide in benzol, especially if the latter is for nitration purposes. Probably the best method depends upon the formation of potassium xanthate by the interaction of the carbon disulphide and alcoholic potassium hydroxide. The xanthate may then be dealt with in several ways : — (a) Titration, after solution in water and acidify- ing, with a standard solution of copper sulphate. (5) Addition of an excess of copper sulphate to an acidified aqueous solution of the xanthate, filtration, washing, and ignition of the precipitated xanthate to cupric oxide, which is weighed. (c) The aqueous solution treated with potassium hydroxide and bromine, by which means all the sulphur is oxidised to sulphate. This is precipitated in the form of barium sulphate by adding an excess of barium chloride to the acidified solution. The BaSO4 is filtered off, washed, ignited, and weighed as such. The * “ The Estimation of Benzene and Toluene in Commer- cial Mixtures.” A. Edwards. Journal of Soc. Chem. Ind., 35, 10, 587, is acidified with acetic acid, Fig. 11. AH ft reaction which takes place in the formation of the xanthate is as follows: — CS2 + C2H5H0 + KHO - KC2H5COS2 + H2O The alcoholic potassium hydroxide is made by dis- solving 11 grms. of potassium hydroxide in 90 grms. of absolute alcohol. The standard solution of copper sulphate contains 12-475 grms. of the crystals dis- solved in distilled water, and made up to a volume of 1 litre. Of this solution, 1 c.c. is equivalent to 0-0076 grm. of carbon disulphide. In making a test, 50 grms. of benzol are mixed with an equal weight of the alcoholic potassium hydroxide. The mixture is allowed to react for several hours, with occasional shaking. The xanthate will separate in the form of yellow needles. These are dissolved out by shaking with water in a separating funnel, several times, the aqueous extracts thus obtained being used for the copper titration, after being acidified with acetic acid. If the gravimetric method (5) is adopted, the aqueous extract of the xanthate and an excess of cop- per sulphate added, the precipitated cupric x a n t hate CuC2H,(CO)S2 being filtered off, etc., and weighed finally as cupric oxide with the u s u a 1 precautions. The amount of car- bon disulphide in 90 per cent, benzol aver- ages from 1 to 2 per cent. Since other sulphur compounds are usually present in benzol, in addition to carbon disulphide, it is sometimes desir- able to determine the total sulphur. In doing this, the gen- eral principle is to b u r n a weighted quantity of the ben- zol in a small lam]), with an ample air supply. In burning, the sulphur com- pounds become con- verted into sulphur dioxide. This may be dealt with in sev- eral ways : (a) Absorp- tion in acid or in alkaline solutions of bromine whereby the sulphur is further oxidised to sulphate, and is finally weighed as barium sulphate, after precipitation with an excess of barium chloride. (5) Absorption in an ammoniacal atmosphere, with final oxidation to sulphate, either by bromine water or a little hydrogen peroxide, also finally weighing as barium sulphate. The ammonia may be supplied by placing a few pieces of ammonium carbonate round the burner. In any case, the combustion of the oil must not be too rapid. A very small flame is required, and the process usually extends over several hours. A con- venient type of apparatus for this purpose is shown in fig. 11. In testing for thiophene (C4HzJS), 2 c.c. of benzol is agitated with 20 c.c. of a mercurial solution, consisting of 1 grm. HgO dissolved in 4 c.c. concentrated sulphuric acid, and diluted to 20 c.c. The mixture is heated on a boiling water bath for one hour. It is then cooled and filtered, the precipitate washed with hot water, dried at 110 to 115 degs. Cent., and weighed. Weight x 0-0758 — thiophene. Stone Dusting in Collieries. — We understand that the Stanton Iron Works (Collieries) Limited are about to put down a stone dust grinding machine at the Pleasley Collieries, near Mansfield, Notts. This company recently installed a mill for preparing stone dust at their Teversal pits, the machine put down being the “ Ideal ” mill, manufactured by Messrs. Richard Scholefield, engineers, Leeds. Messrs. Scholefield have received a repeat order for a similar mill at Pleasley pits. French Peat Committee.—The Peat Committee appointed by the French Minister of Public Works comprises: Senators Cauvin, Dupont, Forsans, and Rivet, Deputies de La Porte, Delaroche - Vernet, Deshayes, Giray, Guist’hau, Mauger, Pechadre, and Pottevin; and Messrs. Coste (representing the Ministry of Public Works), Con- stantin (Minister of the Interior), Copaux (Inventions Department), Pelissier (Ministry of Agriculture), Lancien (Ministry of Supplies), and Willems (Ministry of Muni- tions), secretary. Mineral Rights Duty. — In a letter to the Press, Mr. R. T. Pawsey, secretary of the Mineral Owners Associa- tion, observes“ Royalty owners as a body have accepted the mineral rights duty as a permanent tax without oppo- sition, and since its imposition it is estimated that the national revenue has received not less than £1,500,000 from this source. Of this sum it is calculated that.about 3^ per cent., or more than £50,000, is over and above what Par- liament intended to impose when’ in 1910 it put a separate and distinct tax on mineral rents. Surely, the Govern- ment mean that whatever sum came to a royalty owner as income from minerals was to be charged, and had no inten- tion or thought that an owner would not be allowed a small percentage deduction for expenses of management— such as the 5 per cent, permitted to the owner of a surface property. It is hoped that the Chancellor of the Exchequer will so amend the Budget now before the House of Commons as to remove the present inequitable position of a mineral owner, so as to entitle him : (a) To a percentage or other allowance for management; (5) to deduct mineral rights duty paid before paying income tax ; and (c) if he pay super-tax, to deduct both (a) and (5) from the sum upon which such tax is now payable.” THE IfiSTUOTIOlM OF ffilliliW E1GIMEERS. LONDON MEETING. The 66th general meeting of the members of the institution was held in the rooms of the Geological Society, Burlington House, Piccadilly, on Friday, the 15th inst. The President (Mr. Wallace Thorneycroft) —who has been nominated for a further term of office— occupied the chair, and a good attendance of members included the following:—Sir William Garforth, Sir Lindsay Wood, Profs. F. W. Hardwick, H. Louis, A. Lupton, and L. T. O’Shea, Col. W. C. Blackett, Capt. T. FI. Thorneycroft, Dr. J. V. Elsden, Dr. J. S. Haldane, Messrs. J. Ashworth, Chas. Bingham, E. O. Forster Brown, C. A. Carlow, A. Cordner, J. H. Dew- hurst, B. Dodd, R. W. Dron, J. I. Graham, S. Hare, G. L. Kerr, C. C. Leach, W. W. Lloyd, C. McDermid, B. Madew, Wm. Maurice, J. T. Middleton, H. E. Mitton, D. M. Mowat, H. B. Nash, A. J. A. Orchard, R. E. Ornsby, J. D. Paton, J. Simpson, H. S. Smith, S. A. Smith, J. B. Sneddon, T. Stone, P. Strzelecki, N. T. Williams, Wm. Williamson, T. F. Winmill, and T. Fl. Wordsworth. The President announced that the next annual meeting -would be held at Newcastle-on-Tyne on September 13 and 14. He also stated that the council at their meeting just held had awarded the Institu- tion medal for this year to Col. W. C. Blackett. The members had shown their appreciation of the judgment of the council, and when the time came at the next meeting for the presentation of the medal he would have great pleasure in handing it to Col. Blackett. The “Roll of Honour” of the Institution of Mining Engineers continued to grow, unfortunately. It could not be helped. Applications for temporary commis- sions in the tunnelling companies of the Royal Engi- neers were still being granted to suitable members of the institution. Re-election of President. Sir William Garforth said it gave him very great pleasure to be able to announce that the council at their meeting that morning had unanimously nomi- nated Mr. Wallace Thorneycroft to be president for the ensuing year, and he would be duly elected at the Newcastle meeting in September. He would like to say that, in addition to the very valuable presidential address which they had heard from the president at the Glasgow meeting, it had been a matter of great satisfaction to him and other members who were asso- • ciated with him on certain committees to notice the zeal, the energy, and the wisdom that the president had exhibited on certain matters connected with the work of the institution. He did not wish to enlarge upon it too much, but he wanted to assure the mem- bers that the institution was safe in the hands of Mr. Wallace Thorneycroft, and he believed that he would carry on the best traditions of the institution. He hoped, therefore, that the members would show their appreciation of the nomination which had already been made in the way which was usual among mining engineers when they were very well pleased. The President assured the members that he appre- ciated very highly the honour which had been done him last year in electing him as president, and he appreciated still more the suggestion that he should be nominated for another term of office. The work involved was considerable, but it gave him great pleasure at all times to do the very best he could to promote the objects and welfare of the institution, and he would endeavour to do so if elected for another term. He thanked them for their appreciation of the small services which he had already been able to render. Spontaneous Ignition of Coal. Dr. J. S. Haldane then read his paper on “ The Spontaneous Firing of Coal.” (See page 1165.) Discussion. The President, in opening the discussion, said he desired, on his own account and on account of every member present, to associate himself with every- thing that Dr. Haldane had said in reference to the late Sir Arthur Markham and Mr. J. W. Fryar. In initiating the Doncaster Laboratory, they had laid the foundation of a scheme for a closer alliance between pure science and practical working in the industry. It appeared to him that the finest tribute that could be paid to their memory and to honour them for their work was to build upon that foundation to the best of their ability, in order that they and their successors who spent their lives in and about collieries might reap the increased benefits that he was certain would follow the development of that alliance. In the paper that Dr. Haldane had read they had a most valuable ‘resume of the work done at Doncaster laboratory during the last four years. The discovery of the fact that coal takes up oxygen in two different ways— viz., by chemical combination and by solution—was of far-reaching importance. Pyrites used to be blamed for spontaneous combustion, and it was now clearly shown that if finely crushed it was one cause, but that, generally speaking, it was some other kind of material of more than one variety that was attacked at low temperatures by oxygen. What that material was, Dr. Haldane cautiously avoided suggesting. He had asked his friend, Mr. Forgie, to place on record an incident that he remembered which occurred in 1886 in one of the pits under his supervision that was difficult to explain at the time. Mr. Forgie, who was unable to be present, wrote as follows : — The coal which has, in my own experience, given most trouble with spontaneous combustion is the coking coal of Kilsyth, and that only in the Barwood area. The Denny steam coal frequently fired in the holds of vessels, and latterly had to be mixed with other coals to prevent spontaneous combustion. The coking coal seam in most of the Kilsyth area could safely be stacked without any danger of spontaneous combustion taking place, but in the Barwood area, where the coal was of a first-class coking quality, but very friable and soft, and breaking readily up into dust, spontaneous combustion was almost