SECTION OF CHEMISTRY, MINERALOGY, AND METEOROLOGY. J. H. WURTZ, Esq., in the Chair. INVESTIGATION OF THE INTESTINAL FAT OF A LARGE SEA TURTLE. BY DR. CHRISTIAN LINCK, Assistant in the Cambridge Laboratory. A PORTION of the subcutaneous tissue of this animal was presented to me by Prof. Agassiz, with the request that I would make an investigation of the nature of its fat. One pound of the substance was repeatedly boiled with water, which yielded from its surface seven and a half ounces of fat, which was purified by fusing and washing it with water several times. This fat had the consistency of hog's lard, and retained the strong fish-like smell that emanates from all parts of the animal. The color was a light brownish yellow. It easily saponified with a weak ley of caustic soda. This soap solution being supersaturated with sulphuric acid, was transferred into a glass retort, and two thirds of the liquid distilled off. The distilled liquid had the same odor as the distillate obtained from butter under analogous conditions. This liquid mixed with a quantity of baryta water, deposited during evaporation white flakes of the same appearance as the caprylate and capronate of baryta obtained in a similar way from butter. The quantity is apparently so small as not to admit of the isolation of the acid from it in the oily state. Four ounces of the same fat were saponified, and treated as before; to the distillate a quantity of soda was added, and the whole evaporated to two ounces; this was supersaturated with sulphuric acid and one and a half ounces of liquid distilled over. This gave a decided butyric smell and reddened litmus paper strongly, a reaction destroyed, however, by the addition of a few drops of soda solution, indicating the quantity of volatile acid to be very small. Gottlieb has found precisely the same results in the fat of geese. acids remaining on the surface of the decomposed soap liquor was collected, and treated repeatedly in the same manner as the original fat had been, in order to ascertain whether the formation of the volatile fat acids might not be owing to the reaction of the caustic alkali on one of the main constituents of the fat. The fat The distillate still possessed the smell of butyric acid, but less and less after each succeeding operation, so that most probably the volatile acids were formed only during the first saponification, and in the succeeding operations, those parts only which adhered mechanically to the fat after distillation, were given off. The fishy smell of the fat seems to have no connection with the nature of the volatile fat acids, and the substance on which it depends, exists perhaps in no greater quantity than the odoriferous principles of many flowers, which have not yet been isolated. The fat exposed to the dry distillation until two thirds had gone over, yielded a soft distillate, lighter colored than the original fat, from which emanated the strong and repugnant odor of acrolein, the common product of decomposition of glyceryl, the base which combined with fat acids constitutes animal fats. This product of distillation was boiled with water for some time, then filtered through a wet filter and set aside. After twelve hours there were deposited crystalline flakes with the appearance of sebacic acid the principal product of dry distillation of oleic acid. A quantity of the original fat was saponified with oxide of lead, and the lead plaster digested with ether. Nearly the whole of the plaster proved soluble in this menstruum, showing the presence of a large quantity of oleic acid, the only fat acid whose leadsoap is soluble in ether. The oleic acid was prepared from that soap by decomposition of it with sulphuric acid. It presented the appearance of a brown oil, possessing the physical properties of crude oleic acid. It slightly coagulated when cooled with ice. It remained now to search for the fixed, solid fat acids. Different methods were pursued, but the following proved the most satisfactory The mixture of fat acids obtained by decomposition of the original soap, was dissolved in boiling alcohol and set aside for crystallization, the mother-liquor separated by a filter, and the needles which remained purified by very oft repeated re-crystallizations, so that at last their point of fusion did not rise any higher, but remained stationary at 60° C. The product in such state of purity had completely the appearance of hydrated margaric acid, with which it also corresponded in its point of fusion. In this very tedious manner, and with a great loss of substance in the mother-liquors, a quantity of the acid was obtained sufficient for analysis. The soap separated by chloride of sodium, re-dissolved in water, and separated again by sulphate of soda, etc. Part of it was saponified with soda, thus a pure soda soap was obtained, and from it, by double decomposition with nitrate of silver, an insoluble silver-salt was prepared in the usual manner for preparing these compounds. Of this silver salt 0.4795 grms. was ignited, until all organic matter was destroyed, 0.1360 grms.28.36 per cent. of pure metallic silver, remained behind. Varrentrapp obtained from pure margarate of silver, 28.20 per cent. of silver, which agrees very well with the result which I have obtained. By a combustion with chromate of lead, 0.3241 grms. substance yielded Carbonic acid=0.8955 grms., and water 0.361 grms., which makes the composition of the substance: Carbon 75.35 per cent.; hydrogen 12.37 per cent. ; oxygen 12.28 per cent. : Varrentrapp's and Sacc's analyses vary between 75.30 and 75.85 per cent. carbon, and 12.22 and 12.69 per cent. hydrogen. These analy ses prove that the solid acid in the fat operated upon, is identical with margaric acid. The fat could not contain any stearic acid, because if so, this would have accompanied the margaric acid throughout the process of its preparation, and would have raised its point of fusion above 60° C. The soap which the original fat forms with soda, has a yellow tinge, which can be removed mostly when the soap is separated by salt out of a strongly alkaline solution. The alkaline mother-liquors are then of a deep brown color, and on super-saturation with an acid, deposit a small quantity of a brown sticky precipitate, which is soluble in alkali or in alcohol, and seems to consist of fat surcharged with coloring matter. As the result of this investigation, it appears that the fat under examination consists of margarate and oleate of glycirin and a small quantity of the volatile acids of butter; it contains no stearic acid and shows great analogy with the fat of geese. ON AN INSTRUMENT FOR DETERMINING THE VARIATION AND DuraTION OF WINDS. BY PROF. JAMES H. COFFIN. THE Report of the Regents of the University of the State of New York, for the year 1839, contains a description of an instrument that I formerly used to measure the duration of winds from the several points of compass. A vane was attached to the top of a perpendicular shaft, and at the bottom of the shaft a funnel-shaped tube was fastened pointing obliquely downward, so that as the shaft revolved by the action of the wind on the vane, the smaller orifice of the tube would describe a horizontal circle. A small stream of sand, gauged in the same manner as in an hour glass, was constantly running into the tube at the upper orifice, and thence descending to the lower orifice, was distributed into different boxes, (thirty-two in number,) according to the direction of the wind. The quantity of sand collected in each box, showed precisely the length of time that the wind had blown from the corresponding point of compass. The foregoing instrument, which I used about a year and a half, answered a very good purpose, but there were two defects in it. 1st. While it recorded the duration of the several winds with great minuteness, it failed to inform me at what hour and minute they occurred, a point of considerable importance in connection with the study of storms, and several other meteorological phenomena. 2d. It required attention twice a day to replace the sand. With a view to remedy these defects I modified the instrument, by substituting for the stream of sand a row of minute cards, arranged at regular intervals upon a movable band or apron, each card having printed upon its face the number of the day and hour upon which it made the record. The motion of the band or apron was regulated by a clock, in the same manner as in the animometer of Osler. As thus modified it seems to me to possess the following advantages over that instrument: 1st. It operates with more certainty, and as cards cannot fail to make their records at the proper time, whereas a pencil is liable to get out of order. 2nd. Its records are more definite, dividing the winds into thirty-two distinct classes, or a greater number if desired. 3d. It requires attention less frequently. There is no difficulty in making it keep an hourly record for months together without care. 4th. It not only shows the direction of the wind on any given day and hour, as is done by Osler's, but it also prepares its own abstracts, by collecting the records for each point of compass into a separate box, thus saving much labor in reducing them. upon By the motion of the apron the cards are carried forward, so that at the end of each hour one arrives at the roller E, (see Fig.) and falls off into some one of the boxes below, the particular box being determined by the direction of the wind at the time. As each card shows its face the day and hour upon which it fell, the record is complete. For example, suppose that on examining the boxes at the end of the month of July, the cards which I enclose were found in the box labelled "South." It would show that there was a south wind on the 3d day, 18th and 20th hours; on the 18th day, 12th hour; on the 22d day, 24th hour, &c. A, is the Vane. B, is the Perpendicular Shaft. C, is a Horizontal Circular Plate of light material attached to the shaft. E and F, two Rollers communicating motion to the Apron E F from left to right. 1, 2, 3, &c., are minute Cards, placed upon the Apron. G, is a Clock that regulates the motion of the Roller E, and consequently that of the apron D, is a small weight to relieve the Clock. N, NE, E, &c., are paper boxes placed upon the circular plate, to receive the cards, as they fall from the apron at E. B |