NA TURE 



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THURSDAY, JULY 25, x\ 



COMMERCIAL ORGANIC ANALYSIS. 

 Commercial Organic Analysis. A Treatise on the Pro- 

 perties^ Proximate Analytical Examination, and Modes 

 of Assaying, the Various Organic Chemicals and 

 Products employed in the Arts, Manufactures, Medi- 

 cine, dr'c. ; with Concise Methods for the Detection 

 and Determination of their Impurities, Adulterations, 

 and Products of Decomposition. By Alfred H. Allen, 

 F.I.C., F.C.S. Second Edition, revised and enlarged. 

 Volume III., Part I. (London: J. and A. Churchill, 

 1889.) 



IN this instalment of the amplified edition of Mr. 

 Allen's well-known and valuable work of refer- 

 ence, the substances dealt with are the acid derivatives 

 of phenols, also including aromatic acids and tannins, 

 dyes, and colouring matters ; the large additions made to 

 the first edition necessitating the division of the conclud- 

 ing volume into two parts, of which this is the first, the 

 discussion of organic bases, cyanogen compounds, and 

 albuminoids, &c., is reserved for the second part. In 

 consequence, the large majority of the present portion is 

 entirely new, only comparatively short sections on picric 

 acid and basic aniline derivatives having appeared in the 

 first edition, in place of some 270 pages relating to dye- 

 stuffs. Where references to E^nglish translations or ab- 

 stracts of foreign papers are obtainable, the author has 

 deliberately given them in preference to references to the 

 original memoirs appearing in German and other foreign 

 periodicals, on the ground that these publications " are 

 practically, if not absolutely, inaccessible to the great 

 majority of English readers." No doubt so doing saves 

 a considerable amount of trouble to the reader in the first 

 instance ; but, on the other hand, concise abstracts such 

 as are to be found in the Journals of the Chemical Society 

 and the Society of Chemical Industry, Nature, the 

 Chetnical News^ the Pharmaceutical Journal, Sec, are 

 frequently of necessity shorn of many details of especial im- 

 portance to the commercial analyst ; whilst most chemists 

 concerned in the analysis of dye-stuffs and analogous 

 organic products probably possess in their own libraries the 

 leading German and other periodicals, or at least have 

 access to them in the various public libraries in the manu- 

 facturing towns and cities. 



Amongst the phenol and aromatic derivatives Fahlberg's 

 saccharine (benzoyl sulphonic imide) finds a place ; this 

 is stated by the author to be " quite uninjurious, even 

 when taken in considerable quantities," passing un- 

 changed through the system, so that it can be detected 

 in the urine. It would seem, however, that the alleged 

 freedom from noxious effect is a matter still somewhat in 

 dispute, at any rate as regards habitual use ; the difference 

 of opinion on the subject being one reason why the Com- 

 missioners under the Customs and Inland Revenue Act 

 of 1888 exercised their discretion in prohibiting the use of 

 saccharine in beer (May 1888) until further notice. For 

 similar reasons, the addition of salicylic acid to wine is 

 forbidden in France and other countries, although only 

 one part in 10,000 is essential even as a maximum for the 

 preservation of the liquid ; magenta being also prohibited 

 Vol. XL.— No. 1030. 



as a tinting material for sweetmeats, wines, &c., on 

 account of the frequent presence of arsenic therein. 

 The use of picric acid as a bitter for beers or " hop 

 substitute" is rightly condemned by the author, on 

 account of the distinct poisonous properties of the sub- 

 stance, rabbits and dogs being killed by doses of from 

 o-o6 to o-6o gramme (nearly one to ten grains) ; similarly 

 the employment of dinitro-cresol and naphthalene 

 yellow as " saffron surrogates " for tinting butter, cheese, 

 maccaroni, &c., is strongly objected to on the same ground. 

 In all these and many other instances the various methods 

 of detection of the objectionable substances are carefully 

 detailed, the book being largely intended for the use of 

 the public analyst in connection with articles of food and 

 drugs, as well as for chemists and specialists working in 

 other directions. One of the tests for sahcylic acid in beer, 

 recommended on the authority of Bias, is of a somewhat 

 heroic character, and is hardly likely to be adopted by 

 toxicologists as a process of general application : the 

 analyst is required to drinh the beer, and, after three 

 hours, to examine his urine, the colour-reaction with 

 ferric chloride being stated to be then seven times as 

 delicate as with the original beer. Probably it is the 

 adoption of analytical methods of this description that 

 has led to the popular belief that an analytical certificate 

 of having examined edibles " chemically, physiologically, 

 and dietetically, without finding anything injurious to 

 health in them," simply implies that the operator has 

 lunched on the materials, and has not noticed any par- 

 ticular inconvenience resulting therefrom. In cases where 

 injurious substances are believed to be present, it might 

 be preferable to make the vendor of the suspected goods 

 the medium for the application of the test, thus to some 

 extent returning to the mediaeval practice of punishing 

 sellers of adulterated wine by compelling them to swallow 

 a gallon or two of the Hquor, and pouring the remainder 

 of their stock over them as an external application of a 

 sobering nature. 



In the same section, the general chemistry of the tan- 

 nins is discussed, so far as it is at present understood, 

 and the various processes described for the valuation of 

 the numerous tannin-yielding materials occurring in com- 

 merce. From the tanner's point of view, these are divis- 

 ible into two great classes, viz. those which produce a 

 " bloom," or fawn-coloured deposit on leather (such as 

 gall-nuts, divi-divi, sumach, valonia, and oak-bark), and 

 those which do not (such as catechu, hemlock, larch, and 

 mimosa) ; broadly speaking, these two classes yield, with 

 ferric acetate, somewhat different colorations, the first set 

 producing a blue-black, and the second a green, the dif- 

 ference being mainly due to the presence of gallic acid 

 and protocatechuic acid, or derivatives thereof, in the two 

 classes respectively. Curiously, the author has omitted 

 to give, in this connection, any directions for the testing 

 of manufactured leather, the adulteration of which with 

 sulphate of barium (mechanically forced in whilst moist 

 and soft), glucose, and analogous weighting substances, 

 has of late years come somewhat prominently into notice, 

 and indeed occasioned special Government inquiry. In 

 connection with tannin, some interesting facts are re- 

 corded concerning the examination of documents in 

 cases of suspected forgery or alteration where ordinary 

 ink has been used, more recent writing being frequently 



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