ALKALOID

Syn. Vegetable Alkali , Organic Base ; Alkaloïdes ( pl. , -IDES , or -IDÆ ), L.; Alcaloïde , Alcali organ i que , Fr. In chemistry , a name commonly given to any proximate principle of vegetable origin po e ing alkaline or basic properties, however feeble. In its most extended sense the term embraces all organic bases, whether obtained from the animal or vegetable kingdom, or produced artificially. The alkaloids form a numerous and important cla of bodies. They exist in nature nearly always in the form of salts, the acid being often, like themselves, peculiar to the plant, or cla of plants, in which they are found; whilst the medicinal activity of the latter, in most cases, almost entirely depends on their presence. Prep. The following general methods of procuring the alkaloids will be found applicable to such as full directions are not given for under their respective heads:— 1. (When the base is insoluble in water, non-volatile, and existing in the plant in an insoluble form.) The bruised plant is boiled or macerated in water acidulated with hydrochloric or acetic acid, and the liquor, after filtration, is neutralised with an alkali (ammonia, pota a, lime, or magnesia); the resulting precipitate is purified by re-solution in dilute acid, digestion with a little animal charcoal, and subsequent crystallisation, or re-precipitation with an alkali; or the first precipitate is purified by di olving it once, or, if nece ary, several times, in boiling alcohol, which yields the pure alkaloid either on cooling or by evaporation. 2. (When the base is insoluble in water, and non-volatile, but existing in the plant as a soluble salt.) The bruised or sliced plant is boiled or macerated in water, and the filtered liquor precipitated and otherwise treated as before. 3. (When the base is soluble in water, and non-volatile.) An infusion made with very dilute acid, hydrochloric or acetic, is concentrated by a gentle heat; and the residual liquor treated with pota a (or concentrated solution of ammonia) and ether conjointly; after repose, the ethereal solution is decanted and evaporated. For those alkaloids which are insoluble in ether (as morphia and cinch on i a), the previous proce may be adopted. 4. (When the base is both soluble in water and volatile.) The vegetable, in a bruised or divided state, or its extract, is alkalised with pota a and distilled; the distillate is neutralised with dilute oxalic or sulphuric acid, and carefully evaporated to dryne ; the residuum is next digested in alcohol, and the resulting tincture agitated with pota a and ether, the former being in quantity just sufficient to seize on all the acid; lastly, the ethereal solution thus formed, on careful evaporation, leaves the alkaloid nearly pure. It may be further purified by cautious distillation. As some of the alkaloids are soluble in exce of the alkaline precipitant, over-saturation should be carefully avoided; or the precipitant may be used under the form of carbonate or bicarbonate. When lime and magnesia are employed, they are boiled for a few minutes with the solution. Props. Alcoholic or aqueous solutions of the alkaloids generally exhibit an alkaline reaction with vegetable colours. Like the alkalies, also, they combine with acids to form salts which, when di olved in water, are capable of producing the ordinary phenomena of saline double decomposition. Their taste is usually intensely bitter. The majority of the natural alkaloids contain carbon, hydrogen, nitrogen, and oxygen, and are, at ordinary temperatures, solid, and not volatile without decomposition. Some natural alkaloids contain carbon, hydrogen, and nitrogen only; these are, for the most part, liquid at ordinary temperatures, and can be distilled without decomposition. The greater number of the artificial alkalies are composed of carbon, hydrogen, and nitrogen; some, however, contain oxygen in addition. Alkaloids have also been obtained artificially, in which nitrogen is replaced by phosphorus, arsenic, antimony, or bismuth. Most of the alkaloids, as they are obtained in the free state, correspond in function to ammonia, NH 3 , rather than to the fixed alkalies; that is to say, they form salts by direct union with acids, without elimination of water or any other substance. In order to make them strictly comparable to the fixed alkalies, they require, like ammonia, the addition of water (H 2 O) to their formulæ; they may then be considered as hydrates of compound radicles analogous to ammonium. Physiological action. The alkaloids generally po e great medicinal power; some of them act with terrific energy, and are the most violent poisons with which we are acquainted. Perfectly pure aconitia is about 200 times more poisonous than arsenic, and at least 50 times more poisonous than ordinary medicinal pru ic acid. The greater number act on animals in the same way as the plants which produce them, provided they are given in proportionately small doses. Many of them, when judiciously administered, are most valuable medicines. Pois., Ant., . Some of the alkaloids act as narcotic or stupefying poisons; others are cla ed with the narcotico-acrid poisons, or those which produce both narcotism and irritation of the parts they touch. The example of the former; those from aconite and strychnia, of the latter. In large doses of the greater number, narcotism predominates; in smaller ones, irritation; they are rarely coexistent.— Treatm. No common antidote to the effects of this cla of substances has yet been discovered. The only safe treatment, of at all general application, is to immediately clear the stomach by means of a strong and quick-acting emetic (as sulphate of zinc), or the stomach-pump, and to administer copious and continued draughts of astringent vegetable solutions (as of tannin, nut-galls, oak-bark, or what is always at hand—very strong tea or coffee). These may be followed by or combined with a smart purge of castor oil, as soon as the stomach is thoroughly cleared of the poison. M. Bouchardat strongly recommends a solution of iodine, 3 gr., and iodide of pota ium, 6 gr., in pure water, 16 fl. oz., in cases of poisoning by OPIUM , ACONITE , COLCHICUM , DEADLY NIGHTSHADE , HEMLOCK , NUX VOMICA , ., or by the alkaloids obtained from them— ACONITINE , ATROPIA , COL CHIC IN A , CONIA , MORPHIA , STRYCHNIA , ., or their salts; but not where foxglove or in has been taken. The stomach having been well emptied by an emetic, the solution is to be given by wine-gla fuls for some time; the vomiting being still encouraged during the early part of the administration of the antidote. In the case of narcotics (as opium, morphia, .), this is to be followed by the free use of a strong infusion of coffee. According to Dr Garrod, purified animal charcoal is an ‘excellent antidote’ to many of the alkaloids, including those above enumerated, when taken in poisonous doses; as it not merely absorbs them, but, for the most part, renders them inert. To be serviceable it should be recently prepared and fresh-burnt; and should be given in doses of about an ounce at a time, diffused in warm or tepid water, and frequently repeated. The vomiting which follows its use, owing to the warm water, proves advantageous; but after a sufficient time may be le ened by employing le water, or cooler or even cold water. Drowsine , if present, may be combated by the subsequent use of strong coffee or tea, as before. We have seen this plan succeed in several cases.— Lesions. These, like the symptoms, vary. In some cases there are redne and inflammation of the stomach and intestines, and turgescence of the ve els of the lungs and brain; in others, these appearances are either slight or wholly wanting. Wherever there has been much cerebral disturbance, traces of congestion are usually discernible. Detec., Tests, . The identification of the pure alkaloids is extremely simple; but their detection, when combined with organic and colouring matters, is a task of considerable difficulty. One or other of the following plans may be adopted for this purpose: — 1. (Merck.) The matter under examination is digested, for several hours, with concentrated acetic acid, added in sufficient quantity to produce a strongly acid reaction; the fluid portion is then strained from the insoluble matter, and the latter being washed with water acidulated with acetic acid, the mixed liquors are gently evaporated to dryne in a water bath; the residuum of the evaporation is boiled first with rectified spirit, and next with rectified spirit acidulated with acetic acid; the mixed liquors are again evaporated, the residuum redi olved or diluted with distilled water, and carbonate of soda or pota a added to feebly alkaline reaction, and the whole, after evaporation to the consistence of a syrup, set aside to repose for 24 hours; it is now again diluted with water, filtered, and the insoluble portion washed with cold distilled water, and digested with concentrated acetic acid; this last solution is diluted with distilled water, and decoloured with pure blood-charcoal (if it be nece ary); the fluid, either at once, or after cautious evaporation, may then be tested for the alkaloids, in the usual manner. The charcoal previously used should also be tested in the way described below. This method answers admirably with all the NON-VOLATILE ALKALOIDS , and may be applied to the stomach and viscera, and their contents, and to food, ., in cases of poisoning. 2. (Stas.) The suspected matter, in a finely divided state, is digested, at 160° to 165° Fahr., with twice or thrice its weight of strong alcohol acidulated (according to the quantity) with 1 ⁄ 2 dr. to 2 or 3 dr., or more, of pure oxalic or tartaric acid. After a sufficient time, and when the whole has become quite cold, it is thrown on a filter, and the undi olved portion, after being squeezed dry, is washed with strong alcohol. The mixed and filtered alcoholic liquids are then evaporated at a temperature not exceeding 95° Fahr., and, if no insoluble matter separates, the evaporation is continued nearly to dryne ;[19] but if fatty or other insoluble matter separates during the proce of concentration, the concentrated fluid is pa ed through a moistened filter, and the filtrate evaporated nearly to dryne , as before. The residuum is next digested with absolute alcohol, in the cold, the insoluble portion, after filtration, washed with alcohol, and the mixed filtrates again evaporated in the air, or in vacuo. The acid residue is now di olved in a little distilled water, and bicarbonate of soda added as long as effervescence ensues. To this mixture 4 or 5 times its volume of ether is added, and after lengthened agitation (the bottle or tube being held in a cold wet cloth), the whole is allowed to repose for a short time. A little of the supernatant ether is now removed to a small gla capsule or watch-gla , and allowed to evaporate spontaneously. [19] When this leaves oily streaks upon the gla , which gradually collect into a small drop, which emits, when gently heated, a disagreeable, pungent, and stifling odour, the presence of a LIQUID VOLATILE BASE or ALKALOID is inferred; whilst a solid residue or a turbid fluid with small solid particles floating in it, indicates a NON-VOLATILE SOLID BASE . [20] In either case the blue colour of reddened litmus is permanently restored by the residuum. If no residuum is left on the capsule, some solution of pure soda or pota a is added to the liquid, the whole well agitated for several minutes, and the ether (after repose) decanted; an operation which is repeated with fresh ether a second, third, and even a fourth time. The base, or bases (if any are present), will now be found in the mixed ethereal solution, which is, therefore, tested as before. The presence of an alkaloid being detected, the mixed ethereal solutions are allowed to evaporate spontaneously, care being taken, if a volatile alkaloid be present, to neutralise the liquid with an acid before the final evaporation. The last residuum is then tested for the particular alkaloid present, as before. [21] [19] The evaporation, according to Stas, should be conducted under a bell-gla over sulphuric acid, with or without rarefaction of the air; or in a tubular retort through which a current of air is made to pa . [20] A merely disagreeable animal odour, without pungency, is here disregarded. [21] ‘Bulletin de l’Académie de Méd. Belgique,’ ix, 304; ‘Jahrb. f. prakt. Pharm,’ xxiv, 313; . This method, according to Stas, answers well for all the ALKALOIDS which are soluble in ether; including— ACONITIA , ANILINE , ATROPIA , BRUCIA , CODEIA , COL CHIC IN A , CONIA , DELPHIA , EMETIN A , HYOSCYAMINE , MORPHIA (?), NICOTIA , PETININE , PICOLINE , SOLANINE , STRYCHNIA , VERATRIA , . By means of it Stas found nicotia in the heart-blood of a poisoned dog. With such alkaloids as are, however, only very sparingly soluble in ether (as morphia for instance), the result must, nece arily, be doubtful. To detect these, as well as all the alkaloids which are insoluble in ether, it is, therefore, nece ary, as directed by Otto, to add to the alkaline fluid left by the decantation of the ether, sufficient solution of soda to di olve the morphia, . (if any has separated), and after the expulsion of the last traces of the ether by a gentle heat, to add a concentrated solution of hydro chlorate of ammonia, and to allow the mixture to repose for some time in the open air. When MORPHIA is present, it separates under the form of small crystals. [22] Or the alkaline liquor may be diluted with distilled water, and treated with charcoal, and this with alcohol, in the manner noticed under method 4 ( below ). [22] Otto’s ‘How to Detect Poisons.’ 4. (Graham and Hoffmann—slightly modified.) 2 or 3 oz. of purified animal charcoal are digested in about 1 ⁄ 2 gal. of the (neutral or only slightly acid) aqueous fluid under examination, with frequent agitation, for 10 to 12 hours, or longer. The liquid is then filtered, and the charcoal left on the filter is washed twice with cold distilled water. The charcoal is then boiled for 1 ⁄ 2 an hour with about 1 ⁄ 2 a pint of rectified spirit of 80 or 90%; the ebullition being conducted in a flask having a very long tube, open at both ends, fitted air-tight through the cork, to prevent lo of the alcohol by evaporation. The spirit, which now contains the alkaloid (if any was present in the original liquor), is next filtered whilst hot, and the filtrate is submitted to distillation until the whole of the alcohol is removed. A small quantity (commonly a few drops) of solutions of pota a is then added to the residual aqueous liquor, followed by 1 to 2 fl. oz. of pure ether, after which the whole is well agitated for several minutes, and allowed to repose for a short time. Lastly, the supernatant ether is decanted, and allowed to evaporate spontaneously, when the residuum (if any) left in the capsule may be tested by reagents, as before. This method was devised for the detection of STRYCHNIA and NUX VOMICA in malt-liquors; but it is equally applicable to the detection of ANY ALKALOID which is soluble in ether. The CHARCOAL TEST may also be employed to detect alkaloids which are insoluble in ether; but then the base must be sought in the aqueous residuum obtained by the evaporation of the alcohol. [23] [23] ‘Journ. of the Chem. Soc.,’ v, 173. The presence of the alkaloids and their salts, in clear solutions, may be thus determined:— I. (Fresenius).—1. The solution is rendered very slightly alkaline with dilute solution of pota a or soda, added drop by drop:— a. No precipitate is formed; total absence of the alkaloids. (See 4, below .) b. A precipitate is formed:—solution of pota a or soda is added, drop by drop, until the liquid exhibits a strong alkaline reaction:— α. The precipitate redi olves; absence of Brucia, Cinch on i a, Narcotina, Quina, Strychnia, and Veratria; probable presence of Morphia . β. Precipitate does not redi olve, or not completely; probable presence of one or more of the first six of the above-named alkaloids:—the fluid is filtered from the precipitate, mixed with either bicarbonate of soda or of pota a, gently boiled nearly to dryne , and treated with water. If it di olves completely; absence of morphia; an insoluble residue indicates Morphia . 2. The precipitate 1. b. β. is washed with cold distilled water, di olved in a slight exce of dilute sulphuric acid, neutralised with a saturated solution of bicarbonate of soda, and allowed to repose a few hours: [24] — [24] Before setting the gla aside the liquor should be well mixed, and the gla stirrer vigorously rubbed against the sides of the ve el. a . No precipitate; absence of Cinch on i a, Narcotina, and Quina:—the solution is gently evaporated nearly to dryne , and treated with cold water:—if it di olves completely, pa on to 4; if there is an insoluble residue, it may contain Brucia, Strychnia, or Veratria. (See 3.) b. A precipitate:—the filtered fluid is treated as directed at 2 a .; the precipitate is washed with cold distilled water, di olved in a little hydrochloric acid, ammonia is added in exce , and subsequently a sufficient quantity of ether, agitation being had recourse to:— α. The precipitate formed by the ammonia redi olves completely in the ether, and the clear fluid separates into two layers; absence of Cinch on i a; probable presence of Quina or Narcotina . redi olve in the ether, or not completely; probable presence of Cinch on i a , and perhaps also of Quina or Narcotina. The filtered liquid may be tested for these alkaloids as at a . 3. The insoluble residuum after the evaporation of the solution 2. a. , or of the filtrate 2. b. , is now dried in a water bath, and digested with absolute alcohol:— a. It di olves completely; absence of strychnia; probable presence of Brucia , Quina (?), or Veratria :—the alcoholic solution is evaporated to dryne , and, if quina has been already detected, the residue is divided into two portions, one of which is tested for Brucia, the other for Veratria. b. It does not di olve, or not completely; probable presence of Strychnia , and perhaps also of Brucia and Veratria:—the filtered fluid is divided into two portions, and tested separately as at a . 4. The original liquid 1. a . may contain Salicine, a proximate vegetable principle closely allied to the alkaloids:—a portion is boiled with hydrochloric acid for some time; the formation of a precipitate shows the presence of Salicin . (See 2, below .) [25] [25] For further information on this subject, see the admirable ‘System of Qual. Chem. Anal.,’ by Dr C. R. Fresenius. Church ill. II. (Larocque and Thibierge.) Terchloride of gold is recommended, by these writers, as a more decisive test for the alkaloids than the ‘double chloride of gold and sodium’ commonly employed for this purpose. The following are the colours of the precipitates which it produces with the aqueous solution of their salts:— Brucia , milk-brown, pa ing into coffee-brown, and lastly chocolate-brown:— CINCH ON I A , sulphur yellow:— MORPHIA , yellow, then bluish, and lastly violet; in this last state the gold is reduced, and the precipitate is insoluble in water, alcohol, the caustic alkalies, and sulphuric, nitric, and hydrochloric acid; it forms with aqua regia a solution which is precipitated by pro to sulphate of iron:— QUINA , buff-coloured:— STRYCHNIA , canary-yellow:— VERATRIA , pale greenish-yellow. All these precipitates, with the exception mentioned, are very soluble in alcohol, insoluble in ether, and only slightly soluble in water. Those with morphia and brucia are sufficiently marked to prevent these alkalies from being mistaken for each other; and those with brucia and strychnia are, in like manner, easily distinguishable. III.—Mr Wanklyn discriminates the different alkaloids from the estimation of the ammonia they evolve. His proce is as follows:—A small flask with a lateral tube, and connected with a Liebig’s condenser, is charged with about 25 c. c. of an alkaline solution of permanganate potash made by di olving 200 grammes of caustic potash and 8 grammes of crystallised permanganate of potash in 1 litre of water. A minute quantity of the alkaloid carefully and accurately weighed is now introduced, and the mixture slowly distilled. The most satisfactory results are obtained by treating from 1 to 5 milligrammes of the alkaloid in this way, but quantities so small as 1 ⁄ 10 th of a milligram will in skilled hands give accurate results. The ammonia is formed in the distillate by Ne lerising it, as described under Water analysis . For all practical purposes the poisonous alkaloids may be divided into four cla es: (a) Those which yield from 5 to 2 per cent. of ammonia. (b) Those which yield from 2 to 3 per cent. of ammonia. (c) Those which yield from 3 to 5 per cent. of ammonia. (d) Those which yield a larger quantity than 5 per cent., e.g. | I. | | NH3 per cent. | | Solanine yields half its nitrogen as Ammonia | 0·98 | | II. | | Morphia yields half its nitrogen as Ammonia | 2·98 | | Codeine, ditto, ditto | 2·87 | | Papaverine, ditto, ditto | 2·50 | | Veratria, ditto, ditto | 2·87 | | III. | | Atropia yields all its nitrogen as Ammonia | 5·73 | | Narcotine, ditto, ditto | 4·11 | | Strychnia yields half its nitrogen as Ammonia | 5·09 | | Brucine, ditto, ditto | 4·32 | | Aconite, ditto, ditto | 3·50 | | Coneine, ditto, ditto | 4·60 | | IV. | | Nicotine yields half its nitrogen as Ammonia | 10·49 | IV. Dr Guy, as well as others, have made researches, having for their object the determination of the exact temperature at which the poisonous alkaloids melt and sublime. A very minute speck of the substance is placed on a porcelain plate or copper disc, and a square or oval of microscope-covering gla is placed over it, supported by a thin ring of gla or any other convenient substance. Heat is then applied to the plate or copper, and the temperature, as indicated by a thermometer at which the substance fuses or volatilises, is carefully noted. | Fahr. | Cent. | | Canthari dine sublimes as a white vapour without change of form or colour. | 212° | 100° | | Sublime. | Melt. | | Fahr. | Cent. | Fahr. | Cent. | | Morphine | Sublime, melt and yield carbonaceous residue. | 330° | 165° | 340° | 171° | | Strychnine | 345° | 174° | 430° | 224° | | Melt. | Sublime. | | Fahr. | Cent. | Fahr. | Cent. | | Aconitine | Melt, change colour, sublime, and deposit carbon. | 140° | 60° | 400° | 204° | | Atropine | 150° | 66° | 280° | 138° | | Veratrine | 200° | 93° | 360° | 182° | | Brucine | 240° | 116° | 400° | 204° | | in | 310° | 154° | 310° | 154° | | Picrotoxin | 320° | 160° | 320° | 160° | | Solanine | 420° | 215° | 420° | 216° | Selmi’s method of extracting poisonous alkaloids in forensic investigations. The alcoholic extract of the viscera, acidified and filtered, is evaporated at 65° C., the residue taken up with water, filtered to separate fatty matters, and decoloured by means of basic acetate of lead, leaving the solution in contact with the air for 24 hours. It is then filtered, the lead precipitated by means of sulphuretted hydrogen, and the solution after concentration repeatedly extracted with ether. The ethereal solution is then saturated with dry carbonic anhydride, which generally causes a precipitate of minute drops adhering to the sides of the ve el, and containing some of the alkaloids. The ethereal solution is then poured into a clean ve el, mixed with about half its volume of water, and a current of carbonic anhydride pa ed for about twenty minutes, which may cause the precipitation of other alkaloids not precipitated by dry carbonic anhydride. Usually the whole of the alkaloids present in the ether are thrown down by these means, but if not, the solution is dehydrated by agitation with Barium oxide, and then a solution of tartaric acid in ether added to the clear liquid, taking great care not to employ exce of acid. This throws down any alkaloid that may remain. In order to extract any alkaloids that may still remain in the viscera, they are mixed with Barium hydrate and a little water, and then agitated with purified amylic alcohol; the alkaloids may subsequently be extracted from the alcohol by agitation with very dilute sulphuric acid. A knowledge of the different solubilities of the alkaloids will be found an important auxiliary in their analysis. The following is a summary of the relative solubility of the most important of them. The figures denote the number of parts of the liquid required for their solution:— Absolute alcohol. —Strychnine insoluble; brucine soluble. Amylic alcohol. —Solanine (1061); in sparingly soluble; morphine (133); strychnine (122); veratrine, brucine, atropine, aconitine, and picrotoxin, freely soluble. Benzol. —All the poisonous alkaloids, except solanine, are soluble in benzol. Chloroform. —Solanine (50,000); morphine (6550); strychnine (8); the rest freely soluble. Ether. —Solanine (9000); morphine (7725); strychnine (1400); aconitine (777); brucine (440); veratrine (108); atropine, picrotoxin, [26] and in, very soluble. [26] in and picrotoxin, although not alkaloids, are inserted in the above list, because they have a general similarity in chemical properties to them; and for the convenience of the toxicologist. Water ( cold ).—Strychnine (8333); veratrine (7860); morphine (4166); aconitine (1783); solanine (1750); brucine (900); atropine (414); picrotoxin (150); in very soluble. The principal Alkaloids and their Salts, in the state of powder, or with ‘conia’ and ‘nicotia,’ in the state of an oily looking liquid, may be thus distinguished:— 1. a. The powder is treated with nitric acid:—It is coloured red; probable presence of Brucia, Delphia, Morphia, or commercial Strychnia. If the reddened acid becomes violet on the addition of ‘pro to chloride of tin,’ it is Brucia ; if it becomes black and carbonaceous, it is Delphia . If the powder is fusible without decomposition, and strongly decomposes iodic acid, it is Morphia ; if it is not fusible without decomposition, and does not decompose iodic acid, it is Strychnia . b. If instead of a red, the powder strikes a green colour with nitric acid, it is Solania ; if it is insoluble in ‘ether,’ and not reddened by ‘nitric acid,’ it is Emetia ; if soluble in ether, not reddened by ‘nitric acid,’ but melts and volatilises when heated, it is Atropia ; if it is thus affected by ether or nitric acid, but does not volatilise, it is Veratria . (See 2, below .) 2. a. The powder, or (with ‘conia and nicotia’) concentrated liquor, is treated with a drop or two of concentrated sulphuric acid:—A red colour is produced; probable presence of Brucia, Nicotin a, Salicine, or Veratria. If the reddened mixture has at first a roseate hue, turning deep red on the addition of nitric acid, it is Brucia ; if the original substance moistened with solution of pota a evolves the odour of tobacco, it of an intense blood-hue, and the powder agglutinates into lumps like resin, it is Salicine ; if the colour is at first yellowish, changing to blood-red, and ultimately to crimson and violet, it is Veratria . b. If instead of the substance being ‘reddened’ by strong sulphuric acid, no particular action ensues in the cold, it contains either Conia or Strychnia; if a small fragment of bichromate of pota a being now dropped in, produces a rich violet colour, it is Strychnia ; if the original matter on being heated, or treated with solution of pota a, evolves a penetrating, disagreeable odour, somewhat analogous to that from ‘hemlock,’ or to a mixture of those from tobacco and mice, it is Conia . “ Reactions with cero so-ceric oxide. This oxide exhibits characteristic colours with several alkaloids, especially with STRYCHNINE . When strong sulphuric acid is poured upon strychnine, and then a small quantity of cero so-ceric oxide added, a fine blue colour is produced, similar to that which strychnine exhibits with pota ium bichromate, but much more permanent. The blue colour gradually changes to cherry-red, and then remains unaltered for several days. This reaction is capable of detecting one part of strychnine in a million parts of liquid. Brucine similarly treated acquires an orange-colour, gradually changing to yellow; MORPHINE , olive-brown, finally brown; NARCOTINE , brown cherry red, finally wine-red; CODEINE , olive-green, finally brown; QUININE , pale-yellow; CINCHONINE and THEINE remain colourle ; VERATRINE becomes reddish-brown; ATROPINE , dingy yellowish-brown; SOLANINE , yellow at first, finally brownish; EMETINE , brown; COLCHICINE , first green, then dirty brown; ANILINE , after a long time, acquires a blue colour extending from the edges inwards; CONINE becomes light-yellow. Piperine colours the sulphuric acid blood-red, and is turned dark-brown, almost black by the cerium oxide” (Sonnenschein). “ Reactions with picric acid. This acid is a very good precipitant for alkaloids, affording a very delicate test for many of them, and may perhaps also serve for separating them one from another. The precipitation takes place even in solutions containing a large exce of sulphuric acid, and is sometimes complete. Precipitated are, BRUCINE , STRYCHNINE , VERATRINE , QUINIDINE , CINCHONINE , and most of the opium alkaloids; not precipitated , MORPHINE , ATROPINE (English), PSEUDO-MORPHINE , CAFFEINE , and all glucosides” (Hager). The presence of one or more of the alkaloids being shown by any of the preceding methods, a portion of the original clear solution or powder, or of the precipitates or filtrates above referred to, must be treated with their characteristic tests, as given under the individual notices of these articles, so as to set at rest all doubt as to their identity. No single test must ever be relied on as a positive proof. The presence of Brucia, Morphia and Strychnia may be determined in substances which after being mixed with the salts of these alkaloids have undergone the acetous, vinous, or putrefactive fermentation, as shown by Orfila, MM. Larocque and Thibierge, and many other eminent chemists and toxicologists, and confirmed, in numerous cases, by our own experiments. Opium and morphia may thus be readily detected in beer, wine, soup, and milk. A paper by Profe or Dragendorf in the ‘American Chemist’ for April, 1876, may be consulted with advantage. Concluding Remarks. It is a singular fact that none of the organic bases found in plants have yet been formed artificially, although several analogous substances have been thus produced. Closely allied to the alkaloids there also exists an extensive series of neutral proximate principles, which differ from those substances chiefly in the absence of basic properties, and in most of them being destitute of nitrogen. They are usually bitter, and, like the alkaloids, generally represent the active properties of the plants in which they are found; whilst some of them po e considerable medicinal energy. Of this kind are asparagin, elaterin, gentian in, picrotoxin, salicin, . These two cla es of bodies, though actually distinct, are frequently confounded. See Alkali , Organic Bases , Poisons , Proximate Principles , Vegetables , Nomenclature , .; also the individual alkaloids under their respective heads.