cuanha, cinchona, and fquill. The agent he employed was I. JALAP. All the tinctures obtained from this substance by the different menstrua as above, by the aid of maceration, turn more or less milky, he obferves, on the addition of water. Four drachms of each of them, containing the principles extracted from half a drachm of the jalap, being evaporated with neceffary precaution, gave a refiduum as follows: No. 1, gave 6 grains of pure refin. No. 2, No. 3, No. 4, Hence M. 5 grains of refin and I grain of gum. 8 grains of extract, nearly half which was gum. 7 grains, four of which were gum. Dubuc concludes, that in order to prepare the refin of jalap, and alfo a tincture as draftic as poffible, it is necessary to employ alkohol of 36o of strength. A tincture thus prepared might be denominated the alkoholic refinous tincture of jalap. He adds, that a resino-gummose tincture might be kept in the shops, prepared with No. 3, which would be less active, and fitted for making the vinum jalapii. 2. ALOES. Before fubmitting this drug to the action of the graduated alkohols, M. Dubuc tried it with cold water. An ounce and a half of this liquid was infused in two fucceffive portions on 2 drachms of fuccotrine aloes: it diffolved 60 grains of extractive matter, of an infupportable degree of bitterness; the remainder within 8 or 10 grains, was diffolved in alkohol of 36°, and furnished, by evaporation, a refin much lefs bitter than the extractive matter. 'Knowing the proportions in which the extractive matter. and the refin exist in the alkohol, M. Dubuc had recourse to the different menftrua above stated: No. 1 took up a drachm and half, half refin, half extract. No. 2 took up 4 fcruples, 36 grains of which were refin. No. 3, a drachm, a fcruple of Vol. I. Y y which was refin. No. 4 alfo a drachm, of which 10 grains were refinous. From these experiments the author advises the preparation of two fpirituous tinctures of this drug to be kept in the shops; the first made with the aloes in gross substance, and with alkohol of from 36 to 38 degrees; to be called the alkoholic tincture; the second, with alkohol of the fame degree of strength, but with the aloes deprived of its extractive matter by means of water. This might be termed the alkoholic refinous tincture of aloes. " 3. IPECACUANHA. M. Dubuc treats of the choice of this root, the precautions necessary in its pulverization, and the method of preferving the powder unchanged; which confifts in keeping it in small and well closed bottles. He then examines its habitudes with the different alkohols, in the proportion of a drachm to each ounce of the liquid: in these trials, No. I gave, by infusion and evaporation,,9 grains of pure refin. No. 2, 10 grains, of which 8 were refinous, and two gummy. No. 3,12 grains, of which 5 were refinous, the rest gummy. 14 grains, 5 of which were refin, and 9 gum. No. 4, This last tincture not turning milky, like the others, on the addition of water, and appearing to contain the principal virtues of the root, the author judges it a proper one to be adminiftered in the form of draughts; he recommends it also for making the vinum ipecacuanha, and for the preparation of a syrup. For the latter, he recommends the following formula. Ipecacuanha contufæ Aquæ bullientis oz. ii. oz. XX. Poft infufionem per horas 24, cola. Hujus liquoris, libram unam; facchari albi, libras duas. Liquentur fimul leni calore, addendo dum frigefcat folutio, tincturæ alkoholicæ fupradicta uncias quatuor. Each ounce of this fyrup will contain nearly two grains of refin, and about feven grains of the gummy principle of the drug. 4. CINCHONA rubra et grifea. An ounce of each of the graduated alkohols above mentioned, in which a drachm of the red bark had been infused, gave as follows: No. 1,-8 grains of refin, and I grain of extractive matter. No. 2,-7 grains of refin, and 3 of extract. No. 3, 6 grains of each. No. 4, the fame. 'From these products, M. Dubuc offers receipts for two alkoholic tinctures of this bark; obferving that he gives the preference to that made with the weakest alkohol, and which he deems the most proper for preparing a vinum cinchona. He does not, however, propofe its entering into the compofition of a fyrup, as it would render it turbid. "From having found that the cinchona, though exhausted as much as poffible by repeated affufions of cold water, ftill gave a portion of refin when dried and infused in alkohol of 38°, he concludes, that M. Baumé was deceived in fuppofing, that cold water would diffolve all the refin, the gum, and the extractive matter of this drug, and that therefore maceration was preferable to decoction for the preparation of the extract. M. Dubuc diftinguishes two extracts of this bark, one prepared by strong decoction, which contains, according to him, all the active principles, and therefore probably, all the medicinal virtues of the cinchona when taken in substance. The other, prepared by the action of warm water on the cinchona, after it has been deprived of its refinous part by alkohol. 5. SQUILL. The author next examined the tinctures of this drug, as made with the four forts of alkohol above described, in the proportions of one drachm of the dried fquill to an ounce of the liquid. Four drachms of each of these tinctures, when evaporated, gave as follows: No. 1, gave 8 grains of folid matters, 3 of which were refin, and 5 extractive matter. No. 2,9 grains, 3 refinous, and 6 extractive. No. 3,—12 grains, of which two were refin, 2 gum, and 8 extractive matter. No. 4,-14 grains, with the fame quantity as the last of gum and refin, and with 10 grains of extractive matter. The laft tincture appeared to be the most fully impregnated with the different principles of the fquill; and from this the author advises the vinum fcilliticum to be prepared, and also an extract by evaporation : it is likewife well fitted, he thinks, for mixing with the mel fcilliticum, a new formula for which is given. In their account of the memoir of M. Dubuc, the reporters obferve, that they have repeated the experiments related by the author, and have found them in general exact. They agree with him, that it is neceffary to fix precisely the degree of ftrength of the alkohol employed in medicinal preparations, and to banish from use the vague terms, fpirit of wine and rectified Spirit. They recommend the profecution of fimilar experiments, in order to ascertain, with accuracy, the quantity of resinous, gummy, and extractive matters, capable of being drawn, by alkohol of different degrees of ftrength, from the various ingredients of the fimple and compound tinctures of the shops. They obferve farther, that, in the present state of our knowledge, it might be fufficient to employ, in the formation of tinctures, alkohol of two different degrees of concentration: one of from 18° to 20°, for roots, stalks, barks, gum-refins, extractive juices, &c.; fince it has been demonftrated that in this state it. takes up the utmost poffible of their principles; the other of from 36° to 30°, for pure refins, the natural balfams, &c. Instead of the fyrup of ipecacuanha above defcribed, the reporters recommend a more fimple one, made with an infufion of fix pounds of cold water, in three fucceffive portions, on as many ounces of ipecacuanha in fine powder. An ounce of fyrup thus prepared will be equivalent to 12 grains of the powder taken in infufion. It was fuggefted by fome, that the weaker alkohol was preferable for obtaining the refin of jalap, provided care was taken to wash with water the refin thus obtained. To afcertain this point, the following experiments were made. Eight ounces of jalap in coarse powder, were digested in four pounds of alkohol of 36°, and marked No. 1. A fimilar mixture was made, and a fufficient quantity of diftilled water added, to reduce the alkohol to 20° of strength. This was marked No. 2. At the end of four days, the tincture No. 1 was much less coloured than No. 2, which had become of a deep brown hue. They were both filtered, and to each was added of distilled water double the weight of the alkohol employed. The depofit in No. 2 was more abundant, and darker coloured than in the other, and settled more quickly to the bottom of the veffel. The two liquids were then evaporated to dryness. The dried product of No. 1 was a brown, very transparent matter, and weighed an ounce and a half; that of No. 2 weighed 2 ounces, 2 drachms, and 48 grains. This laft was then repeatedly washed with distilled water, which it tinged in colour, and was reduced by this means to 9 drachms 24 grains of pure deficcated refin. This proves clearly, that diluted alkohol extracts a product more confiderable in appearance than the highly concentrated spirit; but that this excess in quantity is at the expense of its purity. Med. & Chirurg. Rev. Dr. Henderson of Edinburgh, in a letter to the editor of Nicholfon's Journal, dated April 1804, relates a number of experiments, which feem to prove decifively that a portion of the azotic gas of the atmosphere is abforbed by the lungs, or at least difappears during refpiration The method of proceeding was briefly as follows. After having afcertained the purity of the atmospherical air by means of the eudiometer invented by Dr. Hope, and knowing the exact bulk of the air contained in the gafometer, the total quan |