High Explosives. By Capt. E. DE W. S. COLVER, Dr.Met., F.C.S., A.I.A.E. London: Crosby Lockwood and Son. 1918. Pp. xx x+830. Price £3 3s. net. THE copious literature in English, German, French, and Italian dealing with high explosives has certainly needed bringing together and summarising, and the author of this book has undertaken a formidable and lengthy task in attempting to deal with practically the whole of it. In the main he has succeeded admirably, although it would not be impossible to find details which could be adversely criticised. For example, the size of the book makes it rather unwieldy, and the same amount of material might well have been c mpressed into much less bulk, it all waste of space had been vigorously avoided, and possibly some unnecessary illustrations cut out. The treatment of coal-tar and petroleum for the recovery of various derivatives is first described in detail, and directions are given for the testing and analysing of raw materials used for making explosives. These directions are hardly tull enough for the analyst to work from them, but on the other hand, they give a general outline of the processes usually adopted and the conclusions to be drown from the results obtained. Methods of nitration are described, and separate chapters are given to the nitro derivatives of the aromatic hydrocarbons, the manufacture, purification, properties, &c., being fully discussed. The rules and regulations regarding the manufacture of nitro-compounds enforced in Germany are reproduced, and full accounts are given of the toxic effects of nitrous fumes, symptoms of poisoning, &c. The general properties of explosives their use and application, &c., are treated in considerable, detail and from an eminently practical standpoint, and the book is bound to take rank as an exhaustive, and authoritative text-book on the chemistry of high explo sives and their uses for both military and industrial purposes. BOOKS RECEIVED. "A System of Physical Chemistry." By Prof. W. C. MCC. LEWIS, M.A.(R.U.I.), D.Sc (Liv.) Pp. viii+204. Second Edition. In Three Volumes. Vol. III. 'Quantum Theory." With two Appendices by JAMES RICE, M.A. London: Longmans, Green, and Co., 30, Paternoster Row. 78. 6d. net. "Coal tar and some of Its Products." By ARTHUR H. WARNES. Pp. xxii+102. London : Sir Isaac Pitman and Sons, Ltd. "An Advanced Course in Quantitative Analysis." With Explanatory Notes. By Prof. HENRY FAY. Pp. vi+111. New York: John Wiley and Sons, Inc. London: Chapman and Hall, Ltd. 1917. 6s. net. "A Systematic Course of Qualitative Chemical Analysis of Inorganic and Organic Substances." With Rxplanatory Notes. By Prof. HENRY W. SCHIMPF. Third Edition, Revised. Pp. ix+187. New York: John Wiley and Sons, Inc. London: Chapman and Hall, Ltd. 1917. 78. net. "Essentials of Volumetric Analysis." An Introduction to CORRESPONDENCE. NUCLEAR ATOMS. = 155 To the Editor of the Chemical News. SIR. The structural alteration of the atom described by Prof. Soddy in the CHEMICAL NEWS of March 7, 1919, makes it possible for hydrogen to have a nuclear positive charge 2 with one electron I, so that the net nuclear charge, representing unit atomic number, balances a single electron in the outer shell. Physicists, however, contemplate a single positive charge as the maximum nuclear charge of the hydrogen atom; but they are thereby faced with a dilemma. Either there are large numbers of charges at an identical point forming the nucleus of the heavier atoms, which many will agree is absurd; or the positive charges representing mass must be numerically doubled to enable the mass units to be stabilised symmetrically, as described in my "Chemistry an Exact Mechanical Philosophy," published in 1900. The fact that "Pope's (?) benzene nucleus" with its ortho-, meta-, and para-positions is anticipated in this work is evidence of a correct theory of the nature of chemical &c., bonds.-I am, FRED. G. EDWARDS. MISCELLANEOUS. Notice of Removal.-Messrs. Henry Faija and Co., of the Portland Cement Testing Works and Chemical Laboratories, request us to announce that they have left their premises in Old Queen Street, and now carry on business at 6. Earl Street, Westminster, S. W. Royal Institution.-Next Thursday, April 3, at 3 o'clock, Prof. A. 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CHEMICAL NEWS, } Estimation of Cyanogen Compounds in Ammonia Liquor April 4, 1919 THE methods of estimation of these substances in crude gas liquor have been either worked out or re-examined most carefully by Linder, whose valuable results have been published in various of the Alkali Inspector's Reports. They are, however, not immediately suitable for employ. ment in the examination of concentrated ammonia liquor, partly on account of the large percentage of ammonia present, but particularly on account of the occasional smallness in quantity of one or other of the cyanogen impurities. Determinations of considerable accuracy can be made very simply by a colorimetric method (compare Young, Alkali Inspector's 43rd Rep., 1906, p. 42), by employing the Lovibond tintometer. The substances to be estimated are:-Ammonium thiocyanate highest percentage met with 0.185 per cent, average quantity about o'06 per cent. Ammonium cyanide ("volatile cyanide"): highest percentage met with o'024 per cent. Ammonium ferrocyanide: highest percentage met with 0:44 per cent, average quantity about o'i per cent. The usual titration method for estimating thiocyanate as cuprous thiocyanate is scarcely admissible in the present connection, mainly on account of the end point being somewhat troublesome (loc. cit., p 47); thus the percentage of ammonium thiocyanate found in two successive examinations in concentrated ammonia liquor was 0.0538 per cent and o·0526 per cent, and in crude liquor 0.237 per cent and o 275 per cent. Feld's method for estimating cyanide can be employed, but it's somewhat tedious; and it is necessary to modify it -on account of the large quantity of ammonia present after adding to the liquid 50 cc. of concentrated lead nitrate solution, by neutralising the remaining ammonia by running in 2/N nitric acid, until a little lead hydroxide still remains undissolved. Distillation and titration are then proceeded with as usual. Feld's method of estimating ferrocyanides, though applicable, is lengthy and cumbersome as compared with Williams' elegant reaction with cuprous chloride (Fourn., 1912, 468). The basis of this scheme of analysis which is being advocated is the following: 1. Conversion of the ammonium thiocyanate into ferric thiocyanate and measurement of the depth of colour obtained. 2. Interaction of a further quantity of the original liquid with ammonium polysulphide, whereby the ammonium cyanide originally present is converted into animo nium thiocyanate, and the estimation of the total ammonium thiocyanate as ferric thiocyanate. The increased quantity found over and above that found directly (without polysulphide treatment) is a measure of the quantity of cyanide originally present. The presence of ferrocyanide compounds causes no complication, as the conversion of any proportion of the ferrocyanide into thiocyanate by the polysulphide solu tion can be avoided. After a considerable number of experiments and trials on known mixtures and on commercial samples, the Reprinted from the Journal of the Society of Chemical Industry, February 28, 1919, xxxviii., p. 43. 157 following procedure is recommended, and it is advised that details be closely adhered to. Estimation of Ammonium Thiocyanate.-10 cc. of the sample is run into about 40 cc. of water and the liquid is acidified with dilute sulphuric acid, shaking and cooling being continuous all the time. Iron alum is added until the liquid becomes red in colour, and it is then warmed to coagulate the precipitate. It is allowed to stand for half an hour, and after filtering and washing the precipitate, and cooling, 10 cc. of acid solution of iron alum (100 cc. of saturated alum- solution with 10 cc. of concentrated nitric acid) is added, the volume is made up to 100 cc., and the liquid examined in the tintometer. diluted by taking 50 cc., adding 10 cc. more of the acid If the depth of colour is too great, the liquid must be alum solution, and making up to 100 cc. If this further addition of iron alum be not made, the dilute solution is less than half as deep in colour as the stronger solution. Estimation of Ammonium Thiocyanate together with Ammonium Cyanide, after Conversion of the latter into Thiocyanate.-If ferrocyanide is absent, 10 cc. of the sample is run into a little water, ammonium polysulphide solution is added until the liquid is distinct yellow, and the mixture is diluted to 100 cc. tion is made (Alkali Inspector's Rep., 1906, p. 47) by The polysulphide soludiluting 200 cc. of o 880 ammonia to one litre, saturating half of this with hydrogen sulphide, adding the other half of the diluted ammonia solution, and then saturating with sulphur (which takes about a week). The liquid under examination is then heated to boiling point, whereby all ammonia is driven off, treated with iron alum as before, and examined in the tintometer. The difference between this reading and that obtained for thiocyanate alone gives, by simple calculation, the percentage of cyanide in the original sample. During the boiling stage, the precipitated sulphur occasionally becomes greenish. This oes not indicate that there is necessarily any appreciable quantity of ferrocyanide in the precipitate; it may be due to a very small trace of sulphide of iron. Estimation of Ammonia Cyanide when Ferrocyanide is present.-The removal of the ferrocyanide is carried out as follows: 25 cc. of the sample is run into polysulphide solution which is to be kept in excess as judged by its yellow colour. After standing for twenty minutes the liquid is acidified with dilute sulphuric acid, with continuous shaking and cooling (the latter precaution is important), and iron alum is added until the liquid becomes reddish in colour. It is then warmed (not above 60° C.) to coagulate the ferrocyanide precipitate; this is helped by the addition of a few crystals of sodium sulphate. After standing for half an hour, the precipitate is filtered off and washed as usual, and 50 cc. of acid iron alum is added to the filtrate. If the volume of the latter is about 500 cc. or more, a small addition of nitric acid is advisable. The different procedures recommended for the estimation of thiocyanate and cyanide, when ferrocyanide is or is not absent, result from the necessity of avoidance of heating when ferrocyanide and polysulphide (added or original) are present together, or when cyanide may react, undesired, with polysulphide. It would be perfectly feasible, however, to employ the method given for the determination of cyanide when ferrocyanide is present to a sample when the latter is absent, but the procedure recommended is a quicker one. Estimation of Ferrocyanide.-The precipitate obtained during the estimation in the previous paragraph consists of ferrocyanide and sulphur. This precipitate is treated according to the method given in the Aikali Inspector's 46th Report, 1909, except that after decomposition by sodium hydroxide, it is distilled according to Williams' method. The applicability of the method, and its limitations, are shown by the following figures obtained from known mixtures:-In 5 cc. of a solution of potassium ferro |