ARTICLE X. On newly discovered Animal Acids. By M. Chevreul.* M. Chevreul has described five new animal acids, to which he has given the names of butiric acid, capric acid, caproic acid, hircic acid, and phocenic acid. The butiric acid is the odorous principle to which soap, made with the butter of cows' milk, and the butter itself, more particularly owe their smell, but not entirely, for these bodies contain the capric and caproic acid, which also impart some odour to them. Butiric acid has, however, by much the strongest odour, resembling, when concentrated, the smell of strong butter and acetic acid; but when the acid is dilute, it smells like butter. The taste of this acid is at first hot, and afterwards sweetish, resembling that of nitric and muriatic ether. The butiric acid is colourless and fluid, and does not solidify at 15° of Fahr. and at 77° its specific gravity is 0-9675. In the state of hydrate it requires a higher temperature to boil it than water, and distils unchanged. It unites in all proportions with water, and when diluted with half its bulk of water, its specific gravity is greater than that of water. Alcohol combines with it in all proportions. When mixed with hogs'-lard, the butiric acid gives it the smell and taste of butter; the lard soon loses its smell by exposure to the air. In volume it is composed of Oxygen. 3 8 11 One hundred parts of this acid saturate 97.58 of barytes. An atom of hydrogen = 1, and of barytes 78; the weight of the atom of butiric acid must be nearly 80. If the analysis had yielded 12 instead of 11 volumes of hydrogen, the composition of this acid would be 3 atoms of oxygen 24, 8 of carbon 48, and 6 of water = 6; the weight of its atom would consequently be 78, instead of nearly 80, as deduced from the composition of butirate of barytes. Butirate of lime resembles its base in being more soluble in cold water than in hot; the butirate of barytes crystallizes in long prisms; 100 parts of water dissolve 36 of this salt. Capric acid is obtained from the same sources as the butiric acid, and resembles it in being colourless, but it has a smell like that of a goat. In taste it is similar to that of the butiric acid. At 5o of Fahr. it exists in the form of small crystals; in the state of hydrate it requires a higher temperature to boil it than water does; it distils unaltered. The specific gravity of capric acid at 65° of Fahr. is 0-910; 100 parts of water dissolve only 0.12 of it, but with alcohol, it combines in all proportions. * From the Annales de Chimie et de Physique, tom. xxiii. p. 16. New Series, VOL. VI. P One hundred parts of it saturate 56-45 of barytes; the weight of its atom is, therefore, 138. The caprate of barytes forms small globular crystals; 100 parts of water dissolve 0.5 part of this salt. Caproic acid is procured from the same substances that yield the butiric and capric acid. It is colourless, its smell is not so strong as that of the capric acid, but it is similar in taste; it remains liquid at 15° Fahr. and at 77°, its specific gravity is 0.923. One hundred parts of water dissolve 15 of it, and its hydrate distils unchanged at a higher temperature than water: with alcohol, it unites in all proportions. It is composed of One hundred parts saturate 72-41 of barytes; its atom must, therefore, be represented by about 108. Supposing the hydrogen to be 20 instead of 19 volumes, the composition of this acid would be 3 atoms of oxygen = 24, 12 atoms of carbon = 72, and 10 of hydrogen = 10, and the weight of its atom 106. Caproate of barytes, when the solution evaporates spontaneously, crystallizes in needles, but if evaporated, it crystallizes at a lower temperature in hexagonal plates. The hircic acid is the odorous principle of soap made of mutton suet; it exists in so very small a quantity, that fewer experiments have been made upon it than upon the preceding acids. It forms an hydrate, which is but little soluble in water, and does not solidify at 32° Fahr. Its smell resembles that of the goat. With barytes, it forms a salt of difficult solubility, while with potash it produces a deliquescent compound. It is this principle which gives mutton broth its peculiar odour. Phocenic acid is the odorous principle of fish oil soap (savon des huiles de dauphin). It is colourless; remains fluid at 24° Fahr. It has a much stronger smell than either the capric or caproic acids. Its hydrate boils at a temperature above that of water, and distils unchanged. Its taste resembles that of those already described. At 77° its specific gravity is 0.932; 100 parts of water dissolve 5.5 of phocenic acid. It consists of One hundred parts of this acid saturate 82.77 of barytes. Its atom must, therefore, weigh about 94. Phocenate of barytes is soluble in equal weight of water at 68° Fahr.: the crystals are large, and appear to be octahedrons. From the analysis, this acid appears to be a compound of 3 atoms of oxygen 24, 10 of carbon = 60, and 7 of hydrogen=7, and the weight of its atom will consequently be 91. ARTICLE XI. On the Cause and the Effects of an Obstruction of the Blood in the Lungs. By David Williams, MD. (To the Editor of the Annals of Philosophy.) Liverpool, Aug. 5, 1823. WHILE investigating the effects of the pressure of the atmosphere upon the lungs, on its admission into the cavities of the chest, I remarked several appearances that militated against every hypothesis advanced, as to the cause of the unequal distribution of the blood after death. Reflecting on what I had witnessed, and thinking I had observed a phenomenon that had escaped the attention of all the physiologists whose writings I had perused, it encouraged me to a further inquiry. The result of my inquiry has been favourable, as it will, in my opinion, unveil the mystery that envelopes the cause of the comparative vacuity of the system circulating arterial blood post mortem. Before entering into the detail of my research, it will be better to premise the nature of the appearances alluded to. In one of my examinations, after the animal had been suffocated, by making a ligature on the trachea, during the acme of inspiration, previous to removing the sternum, I noticed after the action of the heart had ceased, that the blood still flowed into the right auricle and ventricle, and consequently into the pulmonary artery; and that the propelling agent was so powerful as to distend the right auricle and ventricle so forcibly after the pericardium was slit open, as to make it doubtful whether they would not burst, yet at the same time the pulmonary veins were comparatively empty. In this instance it was apparent, that the blood was obstructed in its course through the lungs, and that this obstruction was one of the principal causes of the vacuity of the circulating system of the arterial blood. From the distention of the cavities of the right side of the heart, and the gorged state of the cave, it was evident that no obstacle impeded the return of the blood through the capillaries, from the system at large. In a mechanical point of view, the blood ought to have met with equal impediment in passing through the capillaries, as in passing through the final terminations of the pulmonary artery into the pulmonary veins. Impressed with the comparative emptiness of the pulmonary veins, and as no visible subsidence of the lungs had taken place, I was at a loss how to assign a cause for the obstruction on a mechanical principle. It occurred to me that it was probable that the blood (from its vital principle being exhausted in its route through the system, and from its supply from the thoracic duct being unassimilated), could not pass from the pulmonary artery into the pulmonary veins, without first being acted upon by pure atmospherical air. As such a cause seemed likely to offer a solution for every phenomenon connected with the subject, the idea was cherished, and for further satisfaction, the following investigations were instituted on the canine species. An animal was destroyed by securing the trachea at the acme of inspiration, afterwards the sternum and cartilaginous ends of the ribs were removed. The blood appeared florid in the pulmonary veins, and in the coronary arteries through the pericardium. When the contractions of the left ventricle began to flag, the pulmonary veins became less and less distended, the blood changing from the florid to a darker and darker colour as the currend diminished. At the last contraction the veins flattened, and the left ventricle felt contracted. At this instant, an irregular or fluttering contraction of the mus+ cular fibres of the right ventricle commenced, and continued for a short time, excited seemingly by the stimulus of distention, from the accumulation of blood in its cavity. After the irregular muscular action had ceased, the right ventricle felt soft and distended, the left was still contracted, but not so rigid as immediately after the last systole. The pulmonary veins appeared empty; one of them was opened, when only a temporary oozing of blood followed. The pericardium was then slit open, and the right ventricle soon became enormously distended, yet no blood flowed out of the punctured vein. Another pulmonary vein was opened, followed by a similar oozing of blood. The pulmonary artery was now punctured, and instantaneously the blood gushed out, and deluged the shell of the chest. An animal was examined in the presence of Dr. Traill, after being destroyed in the same manner as the above, and the pulmonary veins were found in the same empty condition after the last systole. From the investigation, the following corollaries are drawn: 1. That the blood is obstructed in its passage through the lungs, on suspension of respiration, while its circulation through the other parts of the body continues. 2. That the obstruction of the blood in the lungs, on suspension of respiration, is not the effect of a mechanical cause. 3. That the obstruction of the blood in the lungs, on suspension of respiration, arises from a deprivation of pure atmospheri cal air. 4. That the blood which is found post mortem in the left auricle and ventricle, is the remnant after the last systole, and the subsequent draining of the pulmonary veins. 5. That the obstruction of the blood in the lungs, on suspension of respiration, is one of the principal causes of the vacuity of the system circulating arterial blood post mortem. 6. That the immediate cause of the cessation of the action of the heart, is a privation of its natural stimulus, arising from the obstruction of the blood in the lungs. Among numerous phenomena observed in health and disease, which I conceive to arise from an obstruction of the blood in the lungs from a deficiency of pure atmospherical air, are the following. Hæmoptysis, in my opinion, is generally the effect of an accumulation of blood in the pulmonary artery, arising from a deficiency of pure atmospherical air in the lungs to decarbonate the blood, immediately on its being conveyed into that viscus. The deficiency may arise from an interruption of the action of the respiratory muscles, as from the immoderate use of the vocal organs, or from inspiring rarified and impure. air, or from the over distension of the stomach, limiting the action of the diaphragm. Public speakers, singers, and performers on wind instruments, are well-known to be the frequent victims of hæmoptysis. The enthusiastic orator, stimulated by the interest of his subject, and proud of the approbation of his audience, endeavours, by every exertion, to make the greatest impression upon his hearers; by so doing he interrupts his respiration, and occasions a partial accumulation of blood in the pulmonary artery. If this interruption is often repeated, the minute branches of the pulmonary artery must become more and more dilated, as well as debilitated, and at last hæmoptysis will suc ceed; or, from habitual irritation, the foundation of a more insidious disease will be laid, I mean tubercular consumption. If the last conclusion be correct, we can account for the frequency of tubercular consumption in countries subject to sudden vicissi tudes of the atmosphere. The consequence of sudden and frequent changes of temperature, must be sudden and frequent floods of blood, as it were, rushing into the lungs, especially into the lungs of those who have a delicate and a highly sensible constitution. The pulmonary arteries of open-chested persons easily accommodate those frequent torrents, as the blood from the capacity of their lungs is immediately exposed to the influence of the atmosphere, and undergoes the necessary change to admit it to proceed onwards without any delay. The pulmonary arteries of narrow-chested persons, on the contrary, soon feel the effects of a sudden increase in the circulating medium, for their lungs are unable to supply the increase of blood immediately with pure air, so as to enable it to proceed onwards without delay; therefore a temporary accumulation takes place in the pulmonary artery, which must irritate its extreme termi nations. Now I flatter myself, that the cause of the phenomenon that reserved the discovery of the circulation of the blood to modern times, and to the honour of our country, has been disclosed, and that no one for the future, however sceptical, will be able to |