Mr. Ince questioned the propriety of adding carbonate of potash to those pills in which no alkali is ordered by the college, as it would be incompatible with many substances occasionally ordered in such pills. A discussion of rather a conversational nature ensued, from which it appeared to be the general opinion of the meeting that the suggestions of Mr. Hulse were worthy of consideration as a means of facilitating the reduction of gum resins to a more tractable and less variable consistence, but that it should not in any way interfere with a strict adherence to the directions of the college in dispensing prescriptions. ADULTERATION OF THE CANTHARIS VESICATORIA BY MR. JOHN MACKAY, A SPECIES of adulteration of the above insect came lately under my notice, which, from its singularity, I am induced to communicate. I do this more readily, as I am not aware of the circumstance having been mentioned before. From an ounce weight of the flies, I picked, in a few minutes, forty-six various coloured glass beads. I estimate the weight of glass in this form to amount to upwards of three ounces in a pound weight of the cantharides. The late Dr. Duncan, in speaking of the adulteration of cantharides, says, "the melolontha vitis is sometimes found mixed in considerable numbers with the cantharides. They are easily distinguished by their almost square body, and as they do not stimulate the skin, should be picked out before the cantharides are powdered.' Pereira, and other writers, mention the powder only as liable to adulteration, and chiefly with euphorbium. In Dr. Christison's last work, he says, "in the entire state cantharides are scarcely subject to adulteration in this country. In Germany, the cetonia aurata of Fabricius, or scarabæus auratus of Linnæus, the golden beetle is sometimes mixed with it; but this insect may be known by its greater proportional breadth and flat belly."+ "There is, therefore, no evidence of any extraneous matter being introduced to the flies, excepting the golden beetle; which, of course, is at once distinguishable from its appearance. The addition of glass beads to cantharides, whether it be accidental or fraudulent, ought to be exposed, as the particles of glass, when reduced to powder with the flies, and applied for the purpose of vesication, must prove a source of extreme irritation to the skin. 55, George Street, Edinburgh, 16th April, 1842. * Vide Duncan's Dispensatory, page 276. It appeared to be the general opinion of the meeting, that the adulteration of the flies, mentioned by Mr. Mackay, was an accidental circumstance, it being thought that the cost of the beads would be as great as that of the cantharides. ON POTATO SUGAR. BY ANDREW URE, M.D., F.R.S. Honorary Member of the PHARMACEUTICAL SOCIETY. ABOUT two years ago, a sample of sweet mucilaginous liquid was sent me for analysis by the Hon. the Commissioners of Customs. It was part of a quantity imported in casks at Hull from Rotterdam; it was called by the importers vegetable juice. I found it to be imperfectly saccharified starch or fecula; and on my reporting it as such, it was admitted at a moderate rate of duty. Three months since, I received a sample of a similar liquid from the importer at Hull, with a request that I would examine it chemically. He informed me, that an importation just made by him of thirty casks of it had been detained by orders of the Excise till the sugar duty of twenty-five shillings per cwt., of solid matter it contained, was paid upon it. It was of specific gravity 1.362, and contained eighty per cent. of ill-saccharified fecula. In the interval between the first importation and the second, an Act of Parliament had been obtained for placing every kind of sugar, from whatever material it was formed, under the provisions of the Beet Root Sugar Bill. As the saccharometer tables, subservient to the levying of the Excise duties under this Act, were constructed by me at the request of the President of the Board, I was aware that fifty per cent. of the syrup of the beet root was deducted as a waste product, because beet root molasses are too crude an article for the use of man. Well saccharified starch paste, however, constitutes a syrup, poor indeed in sweetness when compared with cane syrup or that of the beet root; but then it does not spontaneously blacken into molasses by evaporation, as solutions of ordinary sugar never fail to do when they are concentrated even with great care. Hence, the residuary syrups of saccharified fecula may be all worked up into a tolerably white concrete mass, which, being pulverized, is used by greedy grocers to mix with their dark brown bastard sugars to improve their colour. It is only within two years that sugar has been in this country manufactured from potato starch to any extent, though it has been long an object of commercial enterprise in France, Belgium, and Holland, where the large coarse potatoes are used for this purpose. The raw material must be very cheap, as well as the labour, for potato flour or starch, for conversion into sugar, has been imported from the continent into this country in large quan tities, and sold in London at the low price of sixteen shillings per cwt. The process usually followed by the potato sugar makers is to mix 100 gallons of boiling water with every 112 pounds of the fecula, and two pounds of the strongest sulphuric acid. This mixture is boiled about twelve hours in a large vat, made of white deal, having pipes laid along its bottom, which are connected with a high-pressure steam boiler. After being thus saccharified, the acid liquid is neutralized with chalk, filtered, and then evaporated to the density of about 1.300, at the boiling temperature, or exactly 1.342, when cooled to 60°. When syrup of this density is left in repose for some days, it concretes altogether into crystalline tufts, and forms an apparently dry solid, of specific gravity 1.39. When this is exposed to the heat of 220° it fuses into a liquid nearly as thin as water, on cooling to 150° it takes the consistence of honey, and at 100°Fahr. it has that of viscid varnish. It must be left a considerable time at rest before it recovers its pristine state. When heated to 270° it boils briskly, gives off one-tenth of its weight of water, and concretes on cooling into a bright yellow, brittle, but deliquescent mass, like barley sugar. If the syrup be concentrated to a much greater density than 1.340, as to 1.362, or if it be left faintly acidulous, in either case it will not granulate, but will remain either a viscid magma, or become a concrete mass, which may indeed be pulverized, though it is so deliquescent as to be unfit for the adulteration of raw sugar. The Hull juice is in this predicament, and is therefore, in my opinion, hardly amenable to the new sugar law, as it cannot by any means be worked up into even the resemblance of sugar. Good muscovado sugar from Jamaica, fuses only when heated to 280°, but it turns immediately dark-brown from the disengagement of some of its carbon at that temperature, and becomes in fact, the substance called caramel by the French, which is used for colouring brandies, white wines, and liqueurs. Thus starch or grape sugar is well distinguished from cane sugar, by its fusibility at a moderate heat, and its unalterability at a pretty high heat. Its sweetening power is only two-fifths of that of ordinary sugar. A good criterion of incompletely formed grape sugar, is its resisting the action of sulphuric acid, while perfectly saccharified starch or cane sugar is readily decomposed by it. If to a strong solution of imperfectly saccharified grape sugar, nearly boiling hot, one drop of sulphuric acid be let fall, no perceptible change will ensue; but if the acid be dropped into solutions of either of the other two sugars, black carbonaceous particles will make their appearance. The article which was lately detained by the Excise for the high duties at Hull is not affected by sulphuric acid, as are solutions of cane sugar, and of the well made potato sugar of London; and for this reason I gave my opinion in favour of admitting the so called vegetable juice at a moderate rate of duty. I subjected the solid matter, obtained by evaporating the Hull juice, to ultimate analysis, by peroxide of copper, in a combustion tube, with all the requisite precautions; and obtained in one experiment 37 per cent. of carbon, and in another 38 per cent., when the substance had been dried in an air-bath heated to 275°. The difference to 100 is hydrogen and oxygen in the proportion to form water. Now, this is the constitution of grape sugar. Cane sugar contains about 5 per cent. more carbon, whereby it readily evolves this black element by the action of heat or sulphuric acid. An ingenious memoir, by Mr. Trommer, upon the distinguishing criteria of gum, dextrine, grape sugar, and cane sugar, has been published in the 3d volume of the Annalen der Chemie und Pharmacie. I have repeated his experiments, and find them to give correct results, when modified in a certain way. His general plan is to expose the hydrate of copper to the action of solutions of the above mentioned vegetable products. He first renders the solution alkaline, then adds solution of sulphate of copper to it, and either heats the mixture, or leaves it for some time in the cold. By pursuing his directions, I encountered contradictory results; but by the following method, I have secured uniform success in applying the criteria, and have even arrived at a method of determining by a direct test, the quantity of sugar in diabetic urine. I dissolve a weighed portion of sulphate of copper in a measured quantity of water, and make the solution faintly alkaline, as tested with turmeric paper, not litmus, by the addition of potash ley in the cold, for if the mixture be hot, a portion of the disengaged green hydrate of copper is converted into black oxide. This mixture being always agitated before applying it, forms the test liquor. If a few drops of it be introduced into a solution of gum, no change ensues on the hydrate of copper, even at a boiling heat, which shows that a gummate of copper is formed which resists decomposition; but the cupreous mixture, without the gum, is rapidly blackened at the boiling temperature. I do not find that the gummate is redissolved by an excess of water, as Trommer affirms. Starch and tragacanth comport like gum, in which respect I agree with Trommer; starch, however, possesses already a perfect criterion in iodine. water. Mr. Trommer says, that solution of dextrine affords a deep blue coloured liquid, without a trace of precipitate; and that when his mixture is heated to 85° C. it deposits red grains of protoxide of copper, soluble in muriatic acid. I think these phenomena are dependent, in some measure, upon the degree of alkaline excess in the mixture. I find that solution of dextrine treated in my way, hardly changes in the cold, but when heated slightly becomes green, and by brisk boiling an olive tint is produced; it thus betrays its tendency of transition into sugar. Solution of cane sugar, similarly treated, undergoes no change in the cold at the end of two days; and even very little change of colour, even at a boiling heat, if not too concentrated. Cane sugar, treated by Trommer in his way, becomes of a deep blue; it can be boiled with potash, in excess, without any separation of orange red oxide of copper. Starch, or grape sugar, has a marvellous power of reducing the green hydrate of copper to the orange oxide, but I find it will not act upon the pure blue hydrate even when recently precipitated; it needs the addition in this case also of a small portion of alkali; but ammonia does not seem to serve the purpose, for on using the ammonia sulphate of copper in solution, I obtained unsatisfactory results with the above vegetable products. The black oxide of copper is not affected by being boiled in a solution of starch sugar. "If solution of grape sugar," says Trommer," and potash be treated with a solution of sulphate of copper, till the separated hydrate is re-dissolved, a precipitate. of red oxide will soon take place at common temperature; but it immediately forms, if the mixture is heated. A liquid containing Too of grape sugar, even one millionth part," says he, "gives a perceptible tinge (orange) if the light is let fall upon it." To obtain such a minute result, very great nicety must be used in the dose of alkali, which I have found it extremely difficult to hit. With my regulated alkaline mixture, however, I never fail in detecting an exceedingly small portion of starch sugar, even when mixed with Muscovado sugar; and thus an excellent method is afforded of detecting the frauds of the grocers. I find that manna deoxidizes the green hydrate of copper slowly when heated, but not nearly to the same extent as grape sugar, which reduces it rapidly to the orange oxide. If an excess of the hydrate of copper test be used, there will be a deposit of green hydrate at the bottom of the vessel. To apply these researches to the sugar of diabetic urine-This should first be boiled briskly to decompose the urea and to dissipate its elements in the form of ammonia, as well as to concentrate the saccharine matter whereby the test becomes more efficacious. Then add to the boiling urine, in a few drops at a time, a cupreous mixture containing a known quantity of the sulphate of copper, till the mixture assumes a greenish tint, and continue the heat till the colour becomes bright orange. Should it remain |