735

two local applications which are said to be efficacious, both ir:

neuralgia and common rheumatism,-tincture of aconite, and asolution of veratria in camphorated spirits of wine. I hope soonto see tobacco in the yet more elegant and more easily accessibleform of a solution of nicotine.

Hampstead, Apnl 14th, 1845.

REVIEWS.

Outlines of Chemistry. Part 2. Orgunic Chemistry. By Wii,LIAM GREGORY, M.D., Professor of Chemistry in the Univer-sity of Edinburgh. With Engravings on Wood. 12mo.

pp. viii. 588.

WE spoke of the former part of this work-namely, that on inor-ganic chemistry, as being in advance of all other English sys-tematic works on the subject; the same commendation is evenmore applicable to the present. The recent progress of organicChemistry has been astonishingly rapid; almost every monthlyjournal from France or Germany brings some discovery : a little,too, is beginning to be done at home, and we may not unreason-ably look to have, ere long, the keystone hewn out, which willenable some great mind to construct an harmonious and simpletheory, and arrange into system, the multitudinous and scatteredfacts. In the meantime, a lucid and yet condensed collection ofascertained facts, under such less general principles as have

already been established, or rendered probable, will be found inthe book before us. The style and logical arrangement of theauthor are too well known to require comment, and the modestpretensions of his preface, in which Dr. Gregory represents thisvolume as an introduction to the lectures of Liebig, published inTHE LANCET, by no means expresses all its merits.The following passage will show our readers how much the

work is in advance of all other manuals, and further supply alucid and intelligible introduction to a rapidly developingdepartment of organic chemistry, in which the French and Ger-man chemists are now most actively engaged:-" THEORY OF CHE:lIlCAL TYPES—DOCTRINE OF SUBSTITUTION.

The original and ingenious researches of Laurent have led tothe adoption of what is called the Theory of Types and the Lawor Doctrine of Substitution, which have been supported, and ina great measure estab ished, by Dumas and other distinguishedexperimenters of the French school. The views of Laurent andof Dumas were, for a time, vehemently opposed by some che-mists, especially by Berzelius and Liebig; but although theyhave in some points been modified and restricted, the progress ofdiscovery has gradually led to their general reception, so that re-cently some of the most striking illustrat’ons and proofs of thelaw of substitution have been discovered by Dr. Hoffman, assist-ant to Professor Liebig, and working under his eye.ti As the subject, therefore, is no longer purely controversial, itwould be wrong to omit it from an elementary work, more espe-cially as the doctrine has now taken such a form as to facilitatevery much the study of organic compounds and of their meta-morphoses.

It is not easy to define a chemical type, but in inorganic che-mistry we may say, for example, that hydrochloric acid, H Cl,is the type of a very numerous class of acids, the character ofwhich is, that they contain hydrogen united to a salt radical.

If for chlorine we substitute iodine, bromine, &c., or even

cyanogen, the type remains unchanged, the compound is still anacid, analogous to that which was selected as the type.

Again, common salt, Na Cl, is the type of a very large seriesof salts, in which a metal is united with a salt radical; and if wesubstitute potassium, lead, or stiver, for the sodium, the type isunaltered; we obtain a different salt, but still a salt of the typerepresented by Na Cl.

Here, then, we have the simplest types and the most obvious- cases of substitution ; when iodine or cyanogen is substituted forchlorine in the acid type; or when potassium, lead, or silver. issubstituted for sodium in the salt type ; in both cases without theloss of the type.

Nay, in the salt type, represented by Na Cl, we may not onlyreplace sodium by other metals, but we may also substituteiodine, bromine, &c., or cyanogen for the chlorine, and still thetype will remain unchanged. Iodide of sodium, Na I, bromide

of magnesium, Mg Br., and cyanide of silver, Ag C), are all as

good examples of the salt t3 pe represented by Na Cl, as commonsalt itself is.

It has been proposed, with great propriety, by Baudrimont,to employ certain Greek characters as symbols in representingthe fornrulae of extensive types or of types in general. I shall,therefore, express the above salt type by the formula &Dgr; X, inwhich A stands for any metal or body acting as a metal, and Xfor chlorine or any other radical of analogous power, such ascyanogen. As hydrogen appears to stand alone in the power offorming acids with bodies of the type X. the acid type abovealluded to becomes, in its most general form, H X.

But while it is very easy to understand the extensive substitu-tions which may be effected in the case of both elements of thetype A X, yet we observe that in these substitutions the electricalcharacter ot the elements is retained; and that as A is the posi-tive, and X is the negative element, so they are only replaced,A by positive and X by negative elements respectively.So far as inorganic chemistry is concerned, the study of types

would serve generally to confirm and establish the electro-che-mical theory. At all events, we are not as yet acquainted withmany exceptions to it; we do not usually find oxygen or chlo-rine occupying the place 01 A in a compound, or a metal playingthe part of X. Even in inorganic chemistry, however, there aresome examples of such Interchanges. Manganese in manganicacid, Mn Og, and chromium in chromic acid, Cr Og, obviouslyrepresent the sulphur in sulphuric acrd; and the manganese inh) permanganic acid, Mn2 0,, represents the chlorine in per-chloric acid, CI 0,; while, in its other compounds, manganeseacts as a metal.But the researches of Laurent and Dumas have shown that in

organic chemistry the substitution of one element for another,even where the type is retained, is not limited by the electricalcharacter of the elements. Thus, in acetic acid, H O. C4 H3 O3,the 3 eq. of hydrogen in the anhydrous acid may be re, laced bychlorine, giving rise to the compound H 0, C4 Cl3 03, in whichthe type is so little affected that this substance, chloracetic acid,has properties highly anatogous to those of acetic acid. Here itis evident that the chlorine performs the same function as thehydrogen which it replaces did, and not, as in hydrochloric acid,an opposite function.

Again, in aldehyde. (C4 Hs.) 0 + HO. the 3 eq. of hydrogenin the radical C4 Hs, may be replaced by 3 eq. of chlorine, andwe then have chloral, (C4 CIs,) 0 + H 0, a body of the sametype as aldehyde.Such cases of substitution of chlorine (iodine, bromine, &c.)

for hydrogen, and even of oxygen for hydrogen, without changeof type, are very frequent ; and it is this kind of substitution,so adverse to the electro-chemical theory, which is includedin the theorv of substitutions of Laurent. Those more usualsubstitutions, where one body is replact d by another of similarelectric character, may be viewed as so many examples of thedoctrine of equivalents, the replacing body being equivalentto that for which it is substituted, on the electro-chemicaltheory.

Adopting, then, the views of Laurent, we are compelled toadmit that the electro-chemical theory fails when applied to casesof substitucion of chlorine for hydrogen, &c., where the typeremains unaltered. This is clearly the case ill acetic and chlo-racetic acids ; and Hoffman has recently shown that in certainbasic organic compounds, hydrogen may be replaced hy chlorine,while the new compound retains the basic type and characters.Aldehyde and chloral furnish an example of the same, in a bodyneither acid nor basic.

Here, then. is a fact of very general occurrence, which not onlyproves that the electro-chemical theory of combination is inap-plicable, at all events in many cases, but also tends to establisha very different view-namely, that the electric character of anelement is no permanent or essential property ; and that the typeor character, or general properties of a compound, depend, noton the nature, but solely on the arrangrment, of its elementaryatoms, on the way in which they are grouped to form the com-pound molecule.The reader will remember that, in the section on Isomorphism,

the principle was laid down that the crystalline form of certaintypes of salts, such as the alum type, as well as many other pro-perties of the compounds having those types, were the result ofthe similar grouping of analogous elements. We now see that,according to the law of substitution, as deduced from numerouscareful observations, similarity of properties, or identity of type,are the result of similarity of grouping, even of elements not ana-logous, nay, of elements electrically opposed to each other. It i$evident, therefore, that the arrangement of the elementary mole-cules to form the compound molecule is the circumstance on which

736

depend almost exclusively the properties of the compound, or, inother words, the character of the type.

Substitution may be either complete or partial. In chloraceticacid, and in chloral, the substitution of chlorine for the hydrogenof the radical acetyle C, H3 is complete. But when ether (C4Hs) 0 is acted oa by chlorine, the substitution takes place bysuccessive steps, one equivalent of hydrogen being replaced at a

time, after the oxygen has also been replaced by chlorine. Thuswe have, first-

We thus obtain the series of compounds here indicated, in whichthe hvdrogen is gradually replaced by chlorine, until at last weobtain the compound (C, Cl5) -- Cl = C4 Cl6 = 2 C2 CIs, whichis the perchloride of carbon. Most of these compounds haveactually been obtained ; and it is obvious that they may all he re-ferred to one type. Such a series is called a series of mechanicalexamples of the type in question, or rather ot subtypes retainingthe original character, although modified.

In some cases, hydrogen has been replaced partly by chlorine,and partly by bromine. Laurent has described two compoundsderived from naphthaline by substitution, the empirical formulafor both of which is the following :—C20 H4 Cl3 Br. Yet theproperties of these two compounds are quite distinct, and it iscertain that this difference of properties must depend on a dif-ference in the arrangement of the elements. Now, in the for-mation of these two compounds we have a very beautiful proofof the existence of a difference in the arrangement; for one isproduced when chlorine acts on the compound called by Laurentbronaphtese, C20 H6 Br2 ; while the other is formed whenbromine is made to act on chlonaphtise, C20 II Cl3. It isobvious that in the first case 2 eq. of hydrogen and 1 eq. ofbromine are replaced by chlorine ; while in the second, 1 eq. of

hydrogen is replaced by bromine. While, therefore, all fourcompounds may be deduced from the type C20 Hs. and whileboth the bromine and chlorine play the part of hydrogen, it isimpossible to doubt that each of the 8 eq. of hydrogen has its

special place in the compound molecule of the type, and that,in the two empirically identical fcymulae above given, the1 eq. of bromine does not replace the same eq. of hydrogen,and consequently the bromine occup:es in the two compoundsdifferent positions. The same remark applies to the 3 eq. 01chlorine.We may illustrate our meaning as follows :-Let C20 H8 be

the type. and let each of the eqs. of hydrogen have a numberattached indicating zn its place in the typical molecule. We shallthen have

Now, if we represent the two compounds above mentioned in thefollowing manner, we can then conceive the influence Of arrange-ment on the properties of two compounds having the same empi-rical formula. The first may be

It is only on this principle that we can explain the facts observedby Laurent ; and it is easy to see that the above type, C20 IIe,’will admit of innumerable modifications: for even the subtypeC20 H4 CIs Br. is capable of yielding many more than the twoabove given ; and the change of 1 eq. produces a new subtype,equally fertile in new forms.

In fact, Laurent has actually obtained, as will be shown furtheron, a very large number of what we have called subtypes, fromthe type C20 H8, which is naphthaline, and has established thesame law in reference to many other types."

This clear exposition of the theory of types-a subject onlyglanced at in the lectures of Liebig, at the end of his account ofthe doctrine of compound radicals-evinces in its author high

qualifications as an expounder of chemistry. The facts are so*

recent, that they have scarcely appeared in the journals, at thesame time they are beautifully illustrative of the progress oforganic chemistry. We cordially recommend this work to everyreader who is interested in chemistry.

Practical Qbservalions on the Di.sea.ses most fatal to Children.By P. Hood. London : Churchill, 1845. 8vo, pp. 231.

A CITY of old had been saved could it have produced five good men.L t a single good idea, albeit not an original one, be the salvationof the volume before us from the critic’s condemnation. Mr. Hoodbelieves that inflammation, as a disease, rarely exists in children;and that the contrary opinion being generally entertained andacted on, is the cause of the great mortality which occurs in earlylife. It is perfectly true, that symptoms counterfeiting infla,mma-tion occur under circumstances directly the reverse of this condi-tion : an important fact pointed out many years ago by MarshallHall, a name most strangely omitted by the author. Correct dia-

gnosis, in the cases described by that eminent physician, is of moreimportance than in almost any other: the treatment is curativeor destructive, as it is correctly or incorrectly applied. The

present author, in insisting on the importance of this fact, rendersvaluable service to the community and his profession : but, likeother people who get a single notion into their heads, he has sopampered and nourished his idea, that it has grown into a form-less distorted monster. All the diseases incident to childhood hebelieves to depend on irdation, and not on inflammation, andthat they must be treated accordingly. One of the fatal errorstoo frequently committed in the practice of our profession, is thetreatment of disease by its name. There is nothing in the nama.The bedside physician recollects it but secondarily; he observes thesymptoms, refers them to their cause, and seeks to counteract orto remove it. The book physician refers to his nosology, finds anappropriate designation, and commences his operations accordingto the measured rhythm of his list. And this is the great faultof the present volume. Two cases, given by the author in the

preface, will well illustrate our remarks: he calls them cases of11 puerperal fever" :-

" A lady, aged thirty, of healthy constitution, was seized, threedays after being put to bed, with a violent pain over the abdomen,which became swelled and tense. She was feverish, thirsty, andrestless. Her medical attendant, impressed with the idea ofinflammation, bled her; and for a short time the violence of thesymptoms appeared to abate. At the end of twelve hours, how-ever, she became worse, and the alarming symptoms returned.Her medical attendant now called in a surgeon of great repute,who coincided in the propriety of what had been done, andrecommended a further abstraction of blood, and the administra-tion of active purgatives. She was accordingly leeched andpurged; and died on the third day from the first attack of themalady. The body was opened by the desire of the husband,who thought his wife had not been properly treated, and, at hisrequest, I attended the examination. The external appearanceswere extreme pallor of the face. and blueness about the mouth;the body looked bloodless, and like that of a person who had diedof cholera. Upon opening the abdomen and puncturing theintestines, large quantities of gas escaped: the intestines, whicliwere enormously distended, appeared pale and bloodless. Theuterus was uncontracted, and contained a small quantity of dark=coloured grumous blood.

" A lady, aged thirty-four, remarkable for her excellent health,and her quick recovery after childbirth, was seized, on theevening of the third day of her confinement, in precisely thesame manner as the lady whose case has just been given. I wascalled in next morning,—she had not previously had any medicalaid,-and I found her much exhausted, restless, and in greatpain. I immediately ordered hot bran to be applied to theabdomen, which was extremely painful, and as greatly distendedas before she was put to bed.’’

Purgatives with opium were prescribed, and the patientrecovered. The error here was in the first instance to calleither of the cases puerperal fever, when no such disease existed;

737

the still more serious error was to treat the first patient for adisease which existed but in name. Another striking defect,which constantly presents itself, is a tendency to find fault withothers ;-the author alone is correct in his views, and in his

practice. He is ignorant of what has been previously writtenon the subject which he has treated at so great length :-Had hebeen better informed he would have written less. There is a

quackishness, too, in the character of the book. The author says-"The chief object of this work is to call the attention, not

only of medical men, but of all persons who may be interested inthe matter, to the investigation of the mode of treatment, &c."

Again, we find the "attention of parents," (and why not guar-dians ?) "expressly called to the work."

It will be seen, from the preceding remarks, that our censureis not sweeping. There is some merit in the volume, and it isnot unworthy of the perusal of medical men interested in thetreatment of children’s diseases.

CHEMISTRY, PHARMACY, ANDMATERIA MEDICA.

To the Editor of THE LANCET.CONDENSED MAGNESIA.

SIR,—A paragraph appears in THE LANCET of June 14, respect -ing the methods of preparing heavy magnesia, calcined and car-bonate. It is stated, in a note by the editor, that he suspects thepreparations made by pressure objectionable, and it may be so.*But the heavy carbonate of magnesia, or concentrated magnesia,as some call it, is a most valuable preparation, quickly acted onby weak acids, and so perfectly miscible with water, that evenby the simple stirring with a teaspoon it becomes as smooth asmilk. This being the fact, it is important to prevent confusionas regards the substances, by using the same terms to dissimilarpreparations.A person employed in making the heavy carbonate, told me

that it is accomplished by throwing together the solutions ofsulphate of magnesia and carbonate of soda at a very high tem-perature; the double-elective attraction IS proportionately rapid,and the precipitated carbonate of magnesia fine and dense.

’

Your obedient servant, W. P.Bristol, June gth, 1845.

MYRRH.

This substance, according to Ehrenberg, is derived from thebalsamodendron myrrha. It exudes as an oily juice from the bark,and hardens, on exposure to the air, at the same time acquiringcolour. As it is transmitted by way of Cairo, there is but onecommercial kind, a mixture of good and bad. In the Europeanmarkets it has been sorted, and three kinds are known :-1. Electmyrrh ; 2. Natural myrrh, or in sorts; 3. Indian, or new myrrh.The first consists of the best fragments picked from the mass,large and small, tear shaped and angular, varying in colour fromyellow to a dark brown. Its specific gravity, according to

Martius, is 1.360. The peculiar odour and taste of myrrh arewell known. The second kind not only contains all the impu-rities and worst parts of the original packages, but is furthersophisticated with gum arable, cherry-tree gum moistened withtincture of myrrh, and bdellium. The third kind occurs in large,irregular fragments, brown, or nearly black, and very bitter.Martius describes a fourth kind, which he calls myrrhse alba,the fragments of which resemble gum ammoniacum, being tear-shaped, with a conchoidal fracture. Pure myrrh seems to con-tain about one and a half per cent. of water, and when burnt,leaves three and a half per cent. of white ash, consisting of car-bonate of lime, carbonate of magnesia, sulphate of lime, and per-oxide of iron. Brandes and Braconnot fbund potash and phos-phoric acid.When myrrh is treated with alcohol of s. g. 0.831 at 60° Fah.,

and the residue dried, this is a yellowish whte mass pulverizable,with a faint smell and taste of myrrh. It contains no starch, butdissolves in hot or cold water; the filtered solution leaves aresinous matter on the filter, and when evaporated, yields a gumclosely analogous to gum arabic, to the amount of about 40 percent. of the myrrh employed.On distilling the alcoholic solution, an oily or balsamic fluid is

obtained, which, when purified by repeated solutions and evapo-* We intended our remarks to apply to the calcined magnesia only.—ED.

ration, becomes of a light vinous yellow colour, with a powerfulodour and taste of myrrh. This may be termed myrrhole. Myrrhyields about two per cent. of this oil.The resinous matter left after evaporating the alcoholic solution,

amounts to about 44 per cent. This resin is of a reddish-browncolour, its soluble in ether, acetic and sulphuric acids, and par-tially so in caustic potash and alcohol. lIuriatic acid leaves aflocculent turbid solution. Its melting point is between 1940 and203°. It is obviously a neutral resin, and may be called myrrhine.

Acted on by heat, nayrrhirae becomes converted into an acidresin, 7nyrrhic acid. The analysis of myrrh, therefore, gives in100 parts-

METALLIC SALTS DECOMPOSED BY CHARCOAL.

M. Chevalier, in experimenting with vegetable and animalcharcoal, finds that they decompose acetate and nitrate of leadin solution, whether in water, wine, alcohol, or acetic acid, evenat ordinary temperatures, but more rapidly with the assistanceof heat. If acetate or nit-ate of lead be distilled with water andcharcoal, free acetic acid or nitric acid is obtained. A solutionof one of these salts, dissolved in orange-flower water, is whollydeprived of its lead bv allowing it to stand on charcoal, eitheranimal or vegetable, the charcoal being from ten to twenty timesthe amount of the lead-salt. In decolouring organic fluids bymeans of charcoal, as in medico-legal inquiries, this property ofcharcoal may cause the poison to be overlooked.—ComptesRendus.

Dr. EGAN gives the following summary of the results of his

experience at the Westmorland Lock Hospital, Dublin, in the

DIAGNOSIS AND TREATMENT OF SYPHILITIC DISEASES.

" 1st. I have observed the simple superficial ulcer, unattendedwith indurated margin or base, give rise to a papular eruption,pains resembling rheumatism, increased vascularity of the throat,generally accompanied with enlarged tonsils. In this form Ihave never witnessed the occurrence of rupia, nodes, or ulcera-tion of the back of the pharynx: in this class, which were forthe most part treated without mercury, constitutional symptomsoccurred far more frequently, but were of a milder description thanin those where the opposite plan of treatment was adopted.When topical applications fail, mercury is resorted to for the pur-pose of accomplishing a cure.

"2ndly. That strong presumptive evidence has been afforded,that the matter of gonorrhoea, in its incipient stage, is capable ofproducing a mild form of secondary symptoms; but not havingbeen able to substantiate this opinion by the process of inocula-tion, I cannot, as far as my experience goes, lay it down as anascertained fact.

’° 3rdly. That the excavated ulcer with indurated margins andbase, commonly described as the Hunterian chancre, has, in mylimited number of cases, been succeeded by a scaly eruption andexcavated ulcers of the tonsils; and that in those cases alone

mercury deserves the name of a specific."4th!y. That the phagedsonic ulcer, where it has existed ab

initio, does not owe its characters to any peculiarity of constitu-tion, but to a specific virus, as is evinced in the dissimilarity andinveteracy of the secondary and tertiary symptoms; and that insuch cases mercury is decidedly injurious. And, lastly, that allthe secondary forms of syphilis, with the exception of iritis, arecurable without the aid of mercury; the cure, however, is muchmore protracted, but relapses far less frequent." - DublinJournal.