I do not propose to detail the process of making soda or mineral water, “Carbonic Acid Water,” as it is properly called in the Pharmacopœia. The minutiæ of its preparation may well be left to the experience and practice of the operator. But the formula given in our standard book should not be defective or wrong in prominent principles, it should accord with experience and the improvement of the times. There does not appear to {42} be any good reason for altering the formula of 1820, which was comparatively “well enough” to that of 1830, ’40 and ’50, which is of no value. After designating the description of fountain required, so far, at least, as regards strength (which ought to be equal to the pressure of twenty atmospheres), and material, it should direct it to be supplied with water to the extent of about five sevenths of its capacity, in order to allow of due admixture of gas and water, and of agitation which greatly facilitates it, and the forcing carbonic acid into it to the extent of at least twelve times the bulk of the water. Thirteen or fourteen times is often employed for draught, and seventeen or eighteen times for bottling. It may be, as it has been, said that “a formula for this preparation is not of great moment.” It may be so; it may, perhaps, as safely be left to the skill of the manufacturer and the taste of the consumer, as “Mistura Spiritus Vini Gallici;” but “if it be worth doing at all, it is worth doing well;” if placed in the Pharmacopœia, it should be in accordance with knowledge, and the experience of practical men.

THE SOLUTION OF ARSENITE OF POTASSA has been made by some Apothecaries, with myself, for several years, by substituting 92 grs. of bicarbonate of potassa, as the equivalent of 64 grs. of the carbonate, by which we feel more confident of obtaining a definite compound than by the employment of the Carbonate, as generally procured, which mostly contains silica and other contaminations. The resulting compound is quite satisfactory, and keeps well. We also omit the compound spirit of lavender, making up the measure of a pint with water. Our object in this is two-fold. The solution is more permanent, according to our observation, and the compound spirit of lavender only renders it (if anything) more attractive in taste and smell, to children and ignorant persons.

In making MISTURA FERRI COMPOSITA, it is peculiarly necessary to proceed exactly according to rule, both in the order of its components and in the method of adding them, to produce a correct result. In the Pharmacopœia the six ingredients are set down thus:— {43}

We are directed to rub the first with the last, “and then mix with these” the fourth, the fifth, the second, and “lastly,” the third.

In the written process for making a mixture, which more than most others, requires exact method, and the adding of each of its numerous components in its right order, it would seem to be desirable, for the sake of perspicuity, to set them down in the order in which they are to be used. Here we have to chase about, forwards and backwards, for the one wanted next, and to read over and over the directions, to make sure of getting them right; for few of us make this mixture so often as to be perfectly familiar with the process, without referring to the text. It is not less awkward in this case from the directions chancing to be over leaf. But the formula is otherwise defective, I think, not being quite equal to that of 1830, in which the rose water and spirit of lavender are directed to be added together. Not only should these be mixed before using, but the myrrh, carbonate of potassa and sugar should be triturated well together, and rubbed with successive portions of the mixed liquids, effecting thereby a better solution of the myrrh. The mixture, then complete, except the sulphate of iron, should be put into the vial, and the salt should, by all means, be directed to be selected in clear crystals, to avoid any per salt of iron; it should be quickly powdered in a clean mortar, and added to the contents of the vial. The result is a bluish colored mixture, soon changing to olive green. If the sulphate of iron be not properly selected, or if it be rubbed in the mortar, as inferred from the formula, the mixture is more or less brown and proportionably deteriorated. Of course, we should not “take sulphate of iron in powder.” {44}

In giving directions for making a compound, something, certainly, is to be expected from the knowledge and skill of the manipulator. But essential points should not be left to him, and a formula for a mixture, probably not very often made by Apothecaries throughout our country towns, should be set down so clearly, that a person competent to put up mixtures generally, could make this one the first time he was called upon for it, without needless perplexity, and with sufficient detail of essentials to ensure its being made correctly. I have been frequently told by physicians that, even here, this mixture, requiring so much nicety of manipulation, does not appear to be made right one time in ten. This may not be so much the fault of the Apothecary as of his guide. He makes the mixture but seldom, and if he make it by his Pharmacopœia he does not make it as well as it can be made. For convenient use in the shop, I have the following process written out:—

Triturate together, and add gradually: