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to medical men of a knowledge of the physical agents attheir disposal. Every efficient physician can bring to his aidsuch branches of physics as acoustics, optics, and me-chanics, but from want of proper knowledge electricity isnot utilised as frequently as its importance deserves. Anywork there’ore which brings before us the uses of elec-

tricity as a physical aid to diagnosis mu-t be of interest.Dr. Benuett’s treatise on Electro-Diagnosis has supplieda great want. The reader is not only impressed withthe importance of this somewhat neglected agent, but heis taught how to use it with almost as little trouble and

expense as the u e of the ophthalmoscope entails. Theauthor’s profess’-d object is to convey to his readers "themeaus of utilising at the bedside a physical agent of

great value in the investigation of an obscura class ofdiseases. ’ How thoroughly and ably he has performedhis t ask can only be realised by a perusal of the work.Dr. Dennett is careful to point out that electricityatoas cannot enable us to form an exact diagnosis of ’,auy disease of the nervous system. As the stethoscopeenables us to determine Certain physical changes in the

lungs cr heart, so electricity furnishes us with informationconcerning the anatomical conditions of nerve and muscle,which enables us to complete our diagnosis when combinedwith a knowledge of the history, symptoms, aud other cir-cumstances of the case. Well-marked phenomena are pro-duced by the app’ication of the galvanic and faradaic cur-rents to healthy nerve and muscle, and in disease theseresults are modified. " It is the careful consideration ofthe relations which exist between these two states, and thepractical advantages which result therefrom, which consti-tute the art of electro-diagnosis."A concise and excellent description is given of the

apparatus required for electro-diagnosis. The author’selement board can be conveniently attached to any batterywhich does not possess the ordinary accessories. Dr.Bennett’s ingenious combined electrode will do much to

bring electro-diagnosis into more common use, for the

manipulative dexterity necessary in using the ordinaryapparatus has deterred many from employing electricity.All the essential accessories are contained in the handle ofthe electrode, so that the currents can be graduated, alter-nated, and interrupted by using one hand only. The ana-tomical knowledge required is shortly stated, and the excel-lent plates aid in its acquisition.The chapters on the electrical reactions in health and

disease supply knowledge which is absolutely essential forthe intelligent use of electricity, and should be read by allwho desire to employ it scientifically. The observations onthe relative electric excitability of the nerve-trunks, themotor points, and the muscles are worthy of attention. The

spinal accessory nerve appears to be the most sensitive toelectric irritation. The anterior crural and external pop-liteal nerves are as nearly as possible equal to the medianand facial as regards their electric irrihbility. Such factsare of use when, for example, both legs are paralysed, andwe can derive no information as regards the electric irrita-bility by comparing one leg with the other. The informationwe desire can, however, be obtained by comparing thenerves of the legs with those of nearly equal irritability inthe arms.

A series of cases is given in Chapter VIII. which illustratesthe electrical reactions in the different forms of paralysis.The study of this subject is facilitated by the excellentgrouping of the various paralyses into those resulting fromdisease of the brain, of the spinal cord, of the peripheralnerves, and those of doubtful origin. The cases are wellchosen, and show that electro-diagnosis is a powerfulauxiliary when taken in conjunction with other facts andobservations. Dr. Bennett insists most strongly that_" we

must not expect electricity by itself to act as a mysteriouspower which will give us every information without aninquiry into all the circumstances of the case." In the last

chapter examples are given which prove that electricity canoften give us information which cannot be arrived at byany other methods of investigation, and that its applicationis sometimes essential before we can form a complete dia-gnosis.The work is calculated to supply the medical profession with

scientific information regarding a most important diagnosticagent which has too long been looked upon with mistrust.

OUR LIBRARY TABLE.

Elements of Dental Material Iledica and Tlzcrapeutics, withPharmacopœiÂ. By JAMES STOCKEN, L.D.S.Eng.; assistedby THOMAS GADDES, L.D.S.Eng. and Edin. Third Edition,1882. London : J. and A. Churchill, New Burlington-street. — Both dental students and practitioners must begrateful to Mr. Stocken for the very useful manual ofwhich he has produced a third edition. It contaius, inmost accessible form, information on preparations usedin dental surgery, and recipes of all the known remedie3for the various forms of toothache, with practical hintsas to their application, and on this account it is to becommended especially to the notice of army and navy.surgeons, who, under the existing regulations, are com-

pelled often to act the part of dentis’s when out of thereach of qualified dental-surgeons. The section treating ofnitrous oxide gas is most useful, though the part dealingwith coma, syncope, and apnœ, is rather involved, and thecourse to pursue in the event of a foreign body getting intothe larynx is not even hinted at. A notable feature of thisbook is its clear and large type, for which Messrs. Churchilldeserve all praise. An index of diseases, with the variousremedies numbered according to the page, is an acceptableaddition to the volume, which numbering might be carriedout with advantage in Section VII., and in the classifica-tion of medicines. The literary style of the work issomewhat marred by the frequent occurrence of suchsolecisms as "strichnia," "rarefication," &c. We also

regret to have again to protest against the recoiii-

mendation of internal remedies by dental surgeons, whichthis book obviously encourage?, and it is to be wished thatin future editions the authors may be satisfied with the goodwork they have done in the large field of dental materiamedica without encroaching on the debateable ground ofgeneral medicine.The illeclical Man’s Handy Book. Edited by WILLIAM

SHEPPERSON. London: J. and A. Churchill.-This is an

unpretentious but very handy little book, giving at a glance,in fifty pages, a 1’st of incompatibles, of po’sons andtheir antidotes, a table of doses, a table showing the

strength of the principal pharmaeopceial preparations ofthe chief drugs ; a saturation table, a table of solutionsfor hypodermic use, and a table of spray solutions fromBarber. It can be carried easily in the coat-pocket. Itclaims no merit beyond that of being an accurate and con-cise compilation, and this claim may be recognised.Della Paralisi Regressiva. GLGr.IELmo H. BARLOW,

M.D. Versione Italiana pel Dottor ViRGlxio BOMPIANO.Milan : Vallardi. 1882.—Dr. Barlow’s clinical study of in-fantile paralysis has been translated into Italian. By thetranslator, as well as by Dr. Barlow, the name " regressiveparalysis " is preferred to current term?. The task of trans-lation has been very well and faithfully execute(), and a feworiginal notes have been added. We are glad to see suchcareful and thorough English clinical work rendered accept-able to the Italian medical public.Magnetism. By THOMAS P. TREGLOHAN, Head Master

of St. James’s Science and Art Schools, Keyham, Devonport.x 2

898

London : Longmans and Co.-A useful little text-book, con-taining in a small compass a large amount of information ona subject about which, in these days, a gnat many peopleare anxious to know something.Common British Insects, selected from tlze typical Beetles,

Moths, and Butterflies of Great Britain. By the Rev. J. G.WOOD, M.A. London : Longmans and Co.-This is an

abridged account of the above-named insects, more fullytreated of in the accomplished author’s fascinating volume,"Insects at Home." Beautifully printed and profuselyillustrated, this smaller work is just the kind of pre-sent to offer to a boy or girl at this season of the year,whilst it is not destitute of attractions to persons of maturer

years.Letts’s Diary for 1883, including the Medical Diary, the

Pocket Diary and Almanack, the Office Diary and Almanack,the Rough Diary or Scribbling Journal (two sizes), theClerical Tablet Diary, and the Housekeeper and EngagementBook.—All who have used any one or more of this group ofuseful diaries will welcome their reappearance. By meansof them, professional work as well as business operationsgenerally, are greatly facilitated. Indeed, to those whohave become accustomed to their aid these diaries, or someof them, are simply indispensable.Our Happy Family, being the Little Folks’ Annual for

1883, and Cassell’s Illustrated Almanac, 1883 (Cassell,Petter, Galpin and Co., London), are beautiful specimens ofthe arts brought into requisition for the production ofChristmas books. They certainly do no discredit to the highreputation of the publishing firm from which they are issued.

THE ALKALINE PICRATE OF POTASHTEST FOR GRAPE SUGAR.To the Editor of THE LANCET.

SIR,—For the practical application of the test for grapesugar, referred to, and briefly described, in’my letter in THELANCET of November 18th, and for the indication of the pre-cautions to be observed in its use, both as a quantitative anda qualitative test, several details will have to be carefullyworked out. One of the most interesting results of the use ofthis test is the clear indication which its gives of the fre-quent, if not constant, presence of a trace of sugar in normalurine, a condition asserted as a fact by some high chemicalauthorities and denied by others. On this point see Dr.Parkes on the Urine (p. 11).

I am indebted to my son, G. Stillingfleet Johnson, thejunior demonstrator of chemistry at King’s College, for thefollowing contribution to the chemistry of this interestingsubject. I am, Sir, yours obediently,Savile-row, Nov. 23rd. GEORGE JOHNSON, M.D., F.R.S.

The Pierate of Potash and Caustic Potash Test for GrapeSugar.

GEORGE JOHNSON, M.D., F.R.S.

Several precautions are necessary in the use of this test.First, care must be taken not to employ too strong a solutionof caustic potash, for picric acid is decomposed by con-centrated potash on boiling, ammonia being evolved inabundance, and a dark-brown colour being produced. Theliquor potassæ of the British Pharmacopoeia does not decom-pose picric acid when boiled with the crystals. A solutionof potassic hydrate, containing 20 grammes KHO to 1 litreof water (nearly 2 per cent.) produces no decompositionwhen boiled for many minutes with crystals of picric acid ;whilst the full effect of Moore’s test for grape sugar may beobtained with a solution of this strength. In testing thelimit of delicacy of the potash and picrate test, a 2 per cent.solution of caustic potash was therefore uniformly employed.Secondly, it is necessary to avoid the presence of an excessof picrate, on account of the strong colouring effects ex-hibited by this substance when boiled with excess even ofdilute (2 per cent.) potash solution. It was found impossibleto detect less than 50 parts of grape sugar in 100,000 parts

i- of water, when a saturated cold solution of picrate of pota:lin in 2 per cent. caustic potash was boiled with the grapj

sugar, and the colour produced compared with that obtaintdby boiling an equal volume of water devoid of grape sugar,mixed with the same volume of the alkaline picrate. The

s, deep colour of the alkaline picrate itself interfered with thedelicacy of the test.

n By adopting the following method it is passible to detectthree parts of grape sugar in 100,000 parts. 0.8 c. c. grape

y sugar solution (containing 0’0006776 gramme grape sugar)’; was mixed with 20 c.c. of 2 per cent. potash solution andy 0 5 c. c. of a cold saturated solution of picrate of potash.i- This liquid was boiled for about thirty seconds in a flask.. 20 c.c. of 2 per cent. potash solution + 0’5 c.c. of the same

picrate of potash solution was boiled for an equal length ofr time in another glass flask. The two liquids were then

transferred to two colourless test-tubes, held vertically overe a white porcelain plate in a good light, when that con-

, taining the grape sugar was seen to be very slightly, but, distinctly, darker than the other. This experiment, by

which the limit of delicacy of the test was fixed, willt give a sufficient illzistration of the general method to bef employed, and the precautions necessary in applying thiss delicate test.s As regards the application of this test to the detection of

grape sugar in urine ; since it was observed that normalurine gives a slight indication with the alkaline picrate,

e the interesting question suggested itself whether any othersubstance present in urine is capable of producing a coloura-

r tion on boiling with a solution of potash and potassicpicrate.

, In order to solve this question, if possible, Brucke’a

f method for separating sugar from urine was employed.About half a pint of normal urine, which produced, however,

1 a blood-red colouration with the picrate test, was mixed, with four times its volume of absolute alcohol in a glass

beaker and filtered. To the clear filtrate was added analcoholic solution of ten grammes of caustic potash, and themixture having been well stirrcd was allowed to stand forfour days.The addition of the alcohol throws down a copious pre-

cipitate, consisting of the bulk of the inorganic salts ofthe urine, which are removed by filtration. The alcoholicpotash produces a gradual separation after a day or two

. of a compound of grape sugar with potassic hydrate,,

which is insoluble in the alcohol liquor.’

A few drops of a reddish oily liquid separated out and a. few crystals formed on the sides of the beaker. The clear’ yellowish liquor was now decanted from the sediment, neu-

tralised with dilute sulphuric acid, filtered and distilled toremove the alcohol. The aqueous residue in the retort,which contains the extractives and other substances, gaveno indication of grape sugar with the picrate test ; indeed,it became somewhat paler in colour after boiling with thealkaline solution.The solution in water of the sediment in the beaker, on

the other hand, gave the sugar reaction with alkaline picratevery strongly. This solution was now treated with an ex-cess of solution of basic acetate of lead and filtered, toremove the extractive matters ; the filtrate was freed fromexcess of lead by sulphuretted hydrogen and filtration, andthe resulting clear solution was concentrated by evaporation.On testing with the alkaline picrate, it still gave distinctindications of the presence of grape sugar, and, on furtherconcentration, also with Fehling’s solution. So far, then, thechemical application of this very delicate test seems to con-firm Brucke’s statement that traces of grape sugar may bedetected even in normal urine. Further confirmation ofthis statement can be obtained only from clinical observation.

G. STILLINGFLEET JOHNSON, F.C.S.

PRESENTATION.-The members of the Loyal AlbionLodge of Odd Fellows, Manchester Unity, have presentedtheir surgeon, Dr. Alderson of Hammersmith, with a silver-mounted library inkstand and a collarette, accompanied withan illuminated framed address, in recognition of hisvaluable services to the Lodge for the past fourteen years.A CORONER’S jury at Birmingham has returned a

verdict of "Wilful murder" against a midwife at BalsallHeath, for the improper use of an instrument for the purposeof procuring abortion, death having resulted from theoperation.