On the peculiar Effects produced by certain Odours. VARIOUS cases of idiosyncracy, or peculiarity of temperament with respect to particular effluvia or odours, are recorded not only in the writings of physicians, but also in other publications. The effect produced by the odour of ipecacuanha on the lady of the late Dr. Buckham of Wooler, mentioned by Dr. Trotter in the last Number of the Medical and Physical Journal, I have myself oftener than once witnessed, while residing with that gentleman, So exquisitely sensible, indeed, was she to the effluvia of this substance, that I have known her subjected to dyspnoea, merely in consequence of pulvis ipecacuanha having been incautiously handled, though she was at that time in an adjoining apartment. It may not be here improper to remark, that though this lady was often unavoidably exposed to various medicinal effluvia, not only belonging, like ipecacuanha, to the class of odours termed nauseosi, but also to those denominated tetri, ambrosiaci, &c. yet from none of these did she ever, so far as I know, experience the slightest inconvenience. I have likewise heard of other females being affected in a similar manner by ipecacuanha; hence, I was led to consider this peculiarity to be so well known, that, like Dr. Trotter, I was surprised at Mr. Royston's conceiving he had been the first to remark it. Many individuals, it is also well known, experience a sense of suffocation when a candle is imperfectly extinguished, particularly at night, after retiring to rest; while, on others, it produces no such effect. Nor are the respiratory the only organs which, in certain habits, are affected by particular effluvia. Thus the exhalations of camphor, though far from ungrateful to many, not unfrequently induce head-achs, particularly in females endowed with great nervous sensibility. The stomach is frequently known likewise to suffer, in some individuals, from the impression of particular effluvia on the olfactory nerves. A relative of my own was so sensibly affected by the odour of old ewe cheese, as to be seized with anorexia, nausea, and even sometimes vomiting, whenever he came within the sphere of its exhalations. An acquaintance, supposing that this might proceed rather from the sight than the smell of the substance in question, determined to resort resort to what he considered an experimentum crucis, in order to satisfy his doubts on the subject. With this view, he slipped into his pocket a piece of old cheese; but tho' the subject of his experiment was wholly unconscious of the action, the usual effects were in a short time produced by it. While these, and many other similar facts, which are well known to physicians, serve to demonstrate the sympathetic connection that subsists between the lungs, the stomach, the brain, and the olfactory organ, they also shew us, that some odours or effluvia, though wholly innocuous to the generality of mankind, nevertheless prove highly injurious to others, in consequence of a peculiarity of habit, either innate or acquired. London, July 26, 1810. Report on the Memoirs presented to the Society of Pharmacy at Paris, in consequence of the Prizes offered in the Year 1809. Extracted by M. BOUILLON LAGRANGE from the full Report drawn up by Messrs. NACHET, DEROSNE, and VALLEE. OF nine Memoirs sent to the Society, two have particu larly fixed the attention of the committee. They were written in answer to the following question: "To prepare the acetate of potash, so as to obtain it white and saturated, without employing radical vinegar, and without having recourse to fusion; to point out which of the two, the acid or the alkali, gives it the colouring principle." The first Memoir, with the motto Ex cognitis incognita, is written with great precision. The author, after having ascertained the advantage which would result from obtaining this salt in all its purity by a simple and economical process, begins by inquiring from whence the colouring principle arises: it cannot, he says, be owing to the alkali, when it is considered that the fusion of the acetate of potash renders it insoluble, and that the heat requisite for this fusion is not so strong as that which is necessary for the preparation of any given potash; and on the other hand, it cannot be essential to the acetic acid, when radical vinegar is capable of instant ly ly furnishing a colourless salt. Consequently, this colouring principle must be a foreign substance contained in common vinegar, and which may be introduced into it in distillation. But this same principle is less volatile than the acetic acid, since distilled vinegar leaves a residue of it if we evaporate it a second time: it is not very soluble by itself, and it cannot be dissolved except by the addition. of acetic acid, since it is precipitated, at least in part, when we saturate the latter by potash and finally, it has been ascertained that it is of a vegeto-animal nature, either from the smell which it exhales when placed on hot coals, or by the prussiate of ammonia, which upon distillation furnishes the acetate of potash prepared with distilled vi negar: a product which does not give the same salt prepared with radical vinegar: whence the author concludes that the radical principle which colours the acetate of potash is nothing but a part of the ferment of common vinegar, carried into the distillation and more or less altered by this operation. Independently of this colouring principle, inherent in the constitution of common vinegar, the author of the Memoir mentions another still more capable of making the acetate of potash look brown: this is the empyreumatic oil with which the vinegar is charged when the distillation is carried too far. He further says, that this salt may also be coloured by the oxides of iron and of manganese contained in the alkali, or by the metallic utensils used in its preparation but this colour being merely accidental, we may avoid it entirely by using a purę potash and vessels of tin or porcelain. We must therefore adhere to the ferment and the empyreumatic oil. The following directions are given for avoiding these two colouring principles; the ferment may be separated from the acetate of potash the more easily the less of it there is in the distilled vinegar," and the latter will contain so much the less in its turn; as in common vinegar, the proportion of the ferment will be smaller with respect to that of the acid, on account of the quantity of ferment brought over in distillation being aiways more or less in proportion with that which exists in common vinegar. It follows therefore that it is necessary, above all, to employ common vinegar, which is at once the most acid, and the least charged with ferment; and this requisite may be attained by choosing a clear vinegar, besides being very strong and completely fermented. After the choice of the vinegar, the process of distillation may also have some influence on the quantity of the ferment (No. 139.) contained R contained in distilled vinegar: for, since this principle is less volatile than the acetic acid, the less of it will pass over in distillation, the more slowly this process is conducted; and in this respect we may admit a slight ebullition as being the fittest degree of heat. If the preceding rules have been well attended to, the distilled vinegar will contain so small a quantity of ferment that it will be capable of furnishing immediately an acetate of potash almost entirely colourless; but if, notwithstanding every precaution, the whiteness of the salt still leaves something to be desired, there remains a final method of remedying it, which consists in filtering through charcoal in powder. The action of this substance, although little known as to its theory, is nevertheless certain in its effects; since it is sufficient to boil slightly with it the solution of the acetate as above prepared, in order to obtain it perfectly white after filtration and evaporation carefully managed. As to the empyreumatic oil, there is only one way of avoiding it, which is to stop the distillation of the vinegar at the moment when this principle begins to come over, and the product gives out an empyreumatic smell: for, beyond this term, the vinegar, if still white in appearance, would not undergo any change of colour during the evaporation of the acetate; and this colour, when once produced, could not be removed, either by charcoal powder or by any other means what ever. The second Memoir presents fuller details. Its motto is taken from Boileau: "L'artifice agréable Du plus affreux objet fait un objet aimable.” The author describes in the first instance the various processes hitherto adopted in preparing the acetate of potash. He mentions as the most exact the process of M. Bouillon Lagrange, which consists in crystallizing this salt but he regrets not having been able to put it in practice, from the difficulty of separating the crystallized acetate from the mother waters, which are very thick. In order to obtain as advantageous a result by a more practicable process, he tried double decompositions; be treated acetate of lime with the carbonate or sulphate of potash, but he did not obtain an acetate of potash less coloured than if he had directly saturated the carbonate of potash with distilled vinegar. It would be necessary, as he observes, to employ a cry 9(tallized tallized acetate of lime, but in this case the process would become too tedious and expensive. The decomposition of the common acetate of lead by the carbonate of soda, furnished him with a tolerably white acetate of potash although this method unites with the facility of using it, the advantage of being cheaper, the author of the memoir does not think it right to resort to it, because the smallest negligence in the operation may change a wholesome medicine into a deadly poison. Recuring to the combination described of distilled vinegar and potash, he first inquires, whence arises the colour assumed by this salt during its evaporation he is also aware that it is owing to a foreign principle contained in the distilled vinegar; but he afterwards saw that this substance was very slightly of a colouring nature by itself: he observed that the acetate of potash well saturated, is found as a consequence of its evaporation with an excess of alkali; and it is this excess of alkali which reacts on the foreign principle contained in the distilled vinegar, and colours it. In order to show more clearly this reaction of the potash, he divided into two equal portions a solution of acetate of potash, he evaporated both at the same degree of heat, maintaining constantly in the one an excess of acid, and in the other an excess of alkali: the salt produced by the liquor with excess of acid was much less coloured than that furnished by the liquor with an excess of alkali*. After having ascertained the origin of the colouring principle and the cause which developes it, the author next endeavoured to destroy it; and charcoal, in his opinion, is the fittest agent with this view, he filters the distilled vinegar through charcoal, he then saturates it with carbonate of potash, leaving in it an excess of acid, which he takes care to keep constantly in the liquor during its evaporation. The result is an acetate equally white with that obtained by means of fusion. This process, although very simple, did not appear to him to be practicable, because the acetate of potash is mixed with a certain quantity of acetate of lime, to which *We have reason to believe, from our own experiments, that the potash still reacts, but much less on the colouring principle, even when the liquor contains an excess of acid; since by operating in this manner we always obtain an acetate of potash which is more or less coloured, whilst the same vinegar is capable of furnishing acetate of lime, magnesia, and alumine, which are very white. Soda did not appear to us to act so strongly potash on this principle,Note by the Committee. |