plaisant as to take the blame to himself, this however does not always happen, and the physician necessarily loses in character.

The study of chemistry, considered from this point of view, is urgently neces sary to the physician for daily use; but it embraces a field far too extensive to be acquired with anything like facility. Hence it occurred to us, that some general rules may prove not unacceptable, which may serve as a clue to enable practitioners to shun those gross chemical blunders in the writing of prescriptions.

1. SUBSTANCES MUST NOT BE PRESCRIBED IN SOLUTION WHICH ARE INSOLUBLE.

A. The Aqueous Solution.

As the aqueous solution is the most usual, the most frequent errors are committed in this instance. It is known that water dissolves the so-called soluble salts, extracts, gum, sugar and soaps, not resins, oils, fats, balsams, camphor, nor sulphur, phosphorus, iodine, calomel, &c.

With respect to the salts, or saline combinations, it is necessary to exhibit some which are insoluble or nearly so, though they are still prescribed in the form of solution; we must, however, impart to them solubility by means of other salts which are soluble; in cases of this kind errors are not infrequently committed.

The following substances are insoluble, or nearly so:

Magnesiæ carbonas and m. usta-ferri prussias, et f. phosphas.-pulvis antim. compos.-antimonii sulphuretum auratum,-antim. sulphuretum rubrum,— zinci carbonas, zinci cyanidum, and some other metallic cyanides-to these, also, may be added the pure vegetable alkalies, quinine, cinchonine, salicine, and the sulphate of quinine, so often prescribed in solution; which is dissolved in pure water in extremely small quantity, but readily in water slightly acidified with sulphuric acid.

Of the combinations of iodine and bromine, those of iron are readily solublethe same may be said of the iodide of zinc-iodide of gold is insoluble-the perbromide and protobromide of mercury are very difficult of solution-the periodide and iodide of mercury are insoluble.

With respect to the solution of extracts, it should be observed, that this is perfect in but few cases; partly because the extracts become changed, and a part is rendered insoluble by its combination with oxygen, partly because they contain resinous combinations, especially if they have been prepared by means of alcohol; in these cases the solution is turbid, being partly of a brownish, and partly of a greenish colour.

B. The Alcoholic Solution.

Alcohol chiefly dissolves resins, ethereal oils, balsams, soaps, camphor, and iodine. Of the salts, alcohol dissolves more especially the combinations of chlorine soluble in water, or bichloride of mercury, the chloride of gold, chloride of iron, &c.—the acetates and lactates, the carbonates, sulphates, and phosphates are not at all soluble in alcohol. Alcohol dissolves but a very small quantity of sulphur and phosphorus.

The alcoholic solution of resins, ethereal oils, balsams, camphor, and iodine are thrown down on the addition of water. The salts not soluble in alcohol, gums, also, several extracts, are thrown down from their aqueous solution, by adding alcohol.

c. The Ethereal Solution.

Sulphuric ether dissolves fat, ethereal oils, camphor, phosphorus, and some

combinations of chlorine, as chloride of iron, chloride of gold, and chloride of

mercury.

D. The Oily Solution.

The ethereal oils combine with fluid and solid fats; they dissolve camphor, sulphur and phosphorus, the Dippel oil in great quantity; they are soluble in alcohol. The fatty oils mix with the ethereal oils; they also dissolve camphor, sulphur, and phosphorus; in æther they are readily soluble, in alcohol but slightly so.

When a substance is given in solution, the most indifferent solvent must be employed, lest, when a full dose is to be administered, the action of the solvent should predominate.

2. NO SUBSTANCES SHOULD BE PRESCRIBED TOGETHER, WHICH

mere custom?

MUTUALLY DECOMPOSE EACH OTHER.

This is a principle which may easily be defended, but it is one which must find a stumbling-block raised by usage. But why do we not endeavour to remove this block by the aid of science, a block, too, not set up by justice, but by Were there no re-action in science, we should make no advance, and use and authority, however badly grounded, would become laws. We do not mean to say any thing here against the black and red wash, nor against Goulard's mixture, and several other preparations of that kind. These are useful preparations in the cases where they are indicated. We here intend to guard our readers against those unchemical formula where the intention, as well as the character, of the practitioner simultaneously suffer.

The following general rules may probably serve many a practitioner as a clue, wherein it is to be remarked, that in reference to the medicine which is to be prescribed, and that which is to be avoided, a reciprocal relation always naturally exists.

When salts of baryta, of lead and of lime are ordered, sulphates and free sulphuric acid are to be avoided, as the sulphuric acid yields white precipitates, difficult of solution with salts of baryta, of lead and of lime.

When salts of silver and salts of lead are prescribed, the hydrochlorates and free hydrochloric acid are to be avoided as the chloride of silver is insoluble, and the chloride of lead is difficult of solution.

When metallic salts are prescribed, care must be taken to avoid :

:

a. Combinations of sulphur, especially those that are soluble, as sulphuret of potassium, or of ammonium, as the insoluble black or yellow, or reddish-coloured metallic sulphurets are precipitated. Even when both the metallic salt as also the sulphur-combination are insoluble, their combination should be avoided. Insoluble sulphur-combinations with such as are soluble, may be prescribed together.

b. Soluble carbonates, more especially carbonate of soda, carbonate of potash, as they form insoluble metallic carbonates; this is more especially to be remarked in the salts of iron, lead, copper, zinc, antimony and mercury.

c. The free alkalies and free earths, more especially the aqua ammoniæ causticæ, and the aqua calcis, are to be reckoned here: on mixing the metallic salts with these substances, the metallic oxides are generally thrown down in the state of hydrate. It is necessary to keep this in view when ordering substances for external use; as in ordering corrosive sublimate, calomel, acetate of lead, &c. &c.

d. Extracts, and especially those containing yellow colouring matter, (extr. of cascarilla, bark, rhatany, &c.)

All the metallic salts yield with the extracts, which, with few exceptions, contain a certain quantity of yellow colouring matter, insoluble, flocculent, dark-brown or black precipitates. These are particularly marked in the salts

of mercury, gold, silver, lead, copper, and iron, so that, ordinarily, if the quantity of extract is sufficiently great, the entire metallic salt is decomposed. In the case of mercury the precipitate is dark-brown, in that of gold violetbrown, in silver brown, in lead a dirty brown, in copper a green brown, and in iron black. The narcotic extracts act of course in the same manner. In a combination of acetate of lead, chloride of mercury, or nitrate of silver, with opium or extract of aconite, we must always expect a portion of the metallic salt to enter into combination with the extractive matter and with the vegetable acids of the extract. Usage sanctions such formulæ, but the physician can never account to himself to which combination he is indebted for the favourable effect produced in the case under treatment; in a fomentation, in an eye-water, consisting of acetate of lead, and tincture of opium, it may be that the acetate of lead does not at all come into action, but the acetate of morphium, the meconate and the tannate of lead may be the real agents; the same thing holds good with respect to the composition of the collyrium, consisting of sulphate of zinc and acetate of lead, wherein the insoluble sulphate of lead is formed, and an acetate of zinc continues in solution. If the practitioner attain his end with this, so much the better. Only if he proceeds rationally, he should know, which substances produced the effect.

e. Soaps. Soaps are decomposed by the metallic substances; combinations of the metallic oxides with the fatty acids are separated: this is more especially to be kept in view in the salts of iron, lead, and copper. To order insoluble metallic combinations with soaps, is not at all warranted.

f. Vegetable mucus. It is the salts of lead and iron, more especially, which combine with the mucus, forming insoluble gelatinous masses.

In ordering free or carbonated alkalies or earths, the free acids must be avoided, unless in the one case of effervescing mixtures. Saturations should contain a slight excess of free acid rather than of carbonated alkali. Certain extracts, and those especially rich in salts, but above all extr. aloes cum acid. sulphur. in like manner, decompose the carbonated alkalies, or the ammoniacal combinations formed sometimes by their being kept for a long time in considerable quantity, are broken up, and ammonia is evolved. Hence, in prescribing pill-masses, in which carbonated alkalies and vegetable extracts, as the extract. taraxaci. card. bened. absinth. or the extracts of narcotic plants are contained, great caution is required. The pills in which this action of the constituents on each other, and the development of a gas takes place, become after a time larger and larger, and may swell from the size of a pea to that of a small hazel-nut.

In ordering sulphur combinations, more especially sulphuretted alkalies (sulphuretum potassa) free acids or acid salts must be avoided. But it must be considered that in a neutral fluid an acid may be generated through fermentation, and particularly in substances containing sugar, as for instance in the syrup of white poppies. This circumstance merits particular attention when ordering the kermes with sugar as a linctus. If an acid is generated here in consequence of fermentation, the golden sulphuret is decomposed, sulphuretted hydrogen is formed, and an antimonial oxide, which acts as an emetic.

It has been already mentioned that in ordering sulphur combinations metallic salts in the reguline metals must be avoided. In this respect it is only to be remarked in the case of pills, that we must avoid directing, that the pills in which sulphur combinations exist be covered with gold or silver leaf, as in a little time the metallic covering becomes black.

With respect to the ordering of metallic salts, very different in reference both to their action and to their chemical habitudes, as for instance, of the chloride of gold, nitrate of silver, acetate or sulphate of copper, acetate of lead, chloride of mercury, &c. cautions have been given in the foregoing observations. As these substances are frequently ordered in the form of pills, but when decompo sitions are to be avoided extracts must be shunned, conformably to the experiments which I have formerly instituted on this subject, I propose as a pill-mass

a mixture of equal parts of the pulvis althæ and of sugar, with the necessary proportion of water. When there is no reason to apprehend that the metallic salts will act prejudicially on the organs of deglutition, the form of powder seems most adviseable, and the saccharum lactis then appears to be the most appropriate constituent; however, in the case of corrosive muriate, chloride of gold, or nitrate of silver, the pilular form should be preferred. In solutions, however, these metallic salts, at least with respect to the eye, act still differently in reference to vegetable matters from what they do in the pilular form. An infusion of one ounce of chamomile flowers with 10 grains of acetate of lead or nitrate of silver forms two parts, one a precipitate, wherein the metallic oxide is a metallic salt, and a fluid wherein there is little more than water. These purely empirical formulæ might probably be exchanged for others more judicious and rational, but it would be better, if physicians would make themselves acquainted with the remedies they order, (in the above case the combinations of the acetate of lead or nitrate of silver with the organic, extractive and other matters) as they know, for instance, in the unguentum ctr. decub. antenr., that it is not the acetate of lead and yellow matter, but the tannate of lead that acts.

In ordering the vegetable alkaloids the xanthic acid and the vegetable substances containing yellow colouring matters must be avoided, as there are then formed insoluble combinations; hence it is the substances containing yellow colouring matter are the most appropriate antidotes in cases of poisoning with the vegetable alkaloids. In the same case also iodine must be shunned; this too enters into insoluble combinations.

In ordering soaps, besides the metallic substances already mentioned, the earthy salts and the free acids and acid salts, as also the extr. aloes cum acido sulphur. must be avoided, by which latter remedies the fatty acids are separated; this is more particularly to be kept in view in ordering the sapo stibiatus from which not only the fatty acid is precipitated by the free acids, but also the sulphuret of antimony and hydrosulphuric acid gas is developed. A formula very prevalent in Berlin, but one by no means practically applicable, is the combination of the soaps with extr. al. c. acid. sulphur. corr. The fatty acid is constantly separated.

In like manner in ordering the extracts besides the metallic salts, the free acids must be avoided, by which a portion of the extractive matter is thrown down. Of the earthy sal's alum is more especially to be remarked, which yields precipitates with the extracts, and more especially with the substances containing yellow colouring matter.

In ordering the soluble earthy salts, as chloride of barium, chloride of calcium, sulphate of magnesia and alum, the carbonated alkalies and phosphate of soda are to be avoided, by which free or carbonated or phosphated earths are thrown down. However it is to be remarked that the sulphate of magnesia is not thrown down by the bicarbonate of soda.

In ordering the salts of potash, more especially in case of tartrate of potash, the free tartaric acid is to be avoided, by which bitartrate of potash is thrown down.

In ordering the simple tartrate of potash and also the double salts of tartaric acid, besides free tartaric acid other free acids also are to be avoided, more especially the mineral acids; the salts are decomposed in greater or less quantity, so that partly cream of tartar, and partly metallic combinations, are precipitated. But likewise acid vegetable remedies, as the pulp of tamarinds, &c., when they meet with the tart. tartaris., throw down cream of tartar. This accounts for the sediments which occur so frequently in these popular aperient mixtures.

On saturating common vinegar in saturations, or prepared vinegar, or fresh lemon juice, vegetable substances separate in the form of flocculi; hence it is that these saturations are turbid; but the saturation with distilled vinegar is clear.

The other saturations may be filtered, in which case however there is a loss of carbonic acid.

The combination of calomel with chlorine-combinations, more especially hydrochlorate of ammonia, is frequently productive of mischievous consequences, which is assigned to the formation of corrosive sublimate; this is possible through the medium of the vital process; however it has not been demonstrated by investigations that have been made on the subject outside the animal body. On the contrary, the combination of calomel with the so-called absorbent earths, as carbonate of magnesia or prepared chalk, seems to act prejudicially rather than beneficially, as by these carbonated earths carbonate of mercury is formed, which is obviously more energetic than calomel, and acts differently from it.

Some metallic salts are decomposed in consequence of the accession of the oxygen of the atmospheric air, and especially in the aqueous solution; this occurs chiefly with the salts of iron, as the chloride of iron, lactate of iron, and the ioduret of iron. To prescribe these substances in the aqueous solution is not advisable; their mixture with sugar-juice is to be recommended in preference, and equally judicious is their exhibition in powder with sugar of milk.

It is scarcely necessary to mention that deliquescent salts in powder should be ordered not in boxes, but in bottles. Such are more especially the salts of potash, the tart. tartarisat., tart. ammoniat., potass. carb. etc.

To mix ointments with aqueous or spirituous fluids is possible only to a certain quantity; if the quantity of the aqueous or spirituous solution is too great, it does not combine with the fat. Hence it is not possible to combine the linim. sapon. comp. with an ointment, as the former substance is a solution of soaps in spirit, whereas, on the contrary, the liniment. ammon. blends very well with ointments. If it be necessary to combine a great quantity of aqueous or spirituous substances with ointments, we must use the liquor ammoniæ causticæ as a connecting or binding medium, and partly saponify the fat.

In ordering phosphor. liniment, or ointments containing phosphorus, great caution is necessary that the solubility of the phosphorus in the fat be not overrated, otherwise particles of phosphorus continue undissolved, which may take fire on being rubbed in. One ounce of common fat dissolves from six to eight grains of phosphorus.

It is scarcely necessary to mention that when ordering eye-salves one cannot be too cautious with respect to the fatty acids of the salves ready prepared in the shops, which often baffle the best intention of the practitioner; for this reason an extemporaneous base of the salve should be selected, one prepared from almondoil or wax. In ordering combinations of iodine, especially the iodide of potassium, the fatty acids must be avoided.

A TREATISE ON MENTAL DERANGEMENT. By FRANCIS WILLIS, M.D. Second Edition,

Dr. Willis states that, the attention of the public having been of late much directed to the treatment of the insane, more particularly as regards restraint or non-restraint, he has been induced to re-consider the observations published by him many years ago on the "Cure of Mental Derangement;" the result is, that he is firmly convinced not only of the efficacy, but also of the necessity of restraint in the management of insane persons.

However agreeable, he says, the idea that a system of kind and watchful treatment is only required, he feels convinced that this will not alone avail. “The minds of the insane must be operated upon by control, either in fact or in idea. The greater number may, and certainly ought to be, rendered tractable without bodily restraint; but we must attribute the orderly behaviour we are able to pro