"Second. On dry distillation, it yields sebacic acid, among many other products.

"These properties being so characteristic and peculiar as they are, we might expect to find them with other members of the series; but the sequel will show that such is the case only in part.

"The oleic acid is very widely diffused, forming, as it does, a constituent of all the more important animal fats, and of most of the vegetable fatty oils. In a few cases only is it replaced by other acids constituted according to the same general formula.

H O4, was discovered in a fat obtained

36

"The döglingic acid, C from a species of dolphin. This acid is likewise solid only at low temperatures. Under the influence of nitrous acid, it undergoes a change; but whether an isomeric acid is produced is not yet known. Neither has it been determined whether it yields sebacic acid on dry distillation.

"The brassinic acid is found in the rape-seed oil. It melts at 32 - 33° C., is changed in the air when heated to 100° C., and is very . soluble in alcohol, as are all the members of this series. An isomeric modification results from the action of nitrous acid.

42

"The erucaic acid, C1 H2 O,, is found in the fatty part of the white mustard. It melts at 34°, and is very soluble in alcohol. Farther than this, we know nothing concerning its properties.

"The moringaic acid was found in the poppy oil. It has been but little studied.

"Finally, the hypogaic acid, which has formed the subject of our investigation, is a constituent of the oil obtained from the fruit of the African plant, the Arachis hypogæa, which is known in commerce as the ground-nut or pea-nut.

"To obtain it, the lead salt is first prepared from the crude mixture of the acids which occur in the oil, according to the ordinary method of preparing oleate of lead. This lead salt, on decomposition with a mineral acid, yields a reddish-yellow mass, which, at common winter. temperatures, is a mixture of a reddish-yellow oil, and a white crystalline substance; the latter is the pure acid, the former the product of oxidation by the air. From this mixture the pure acid can be obtained by combining the whole with baryta, repeated recrystallization of the product from an alcoholic solution, and decomposition of this pure salt with a mineral acid. Thus purified, the hypogæic acid forms a white solid fat, which melts at 34° C., and then readily oxidizes

in the air, precisely as is the case with oleic acid. The hypogaic ether, and the copper and baryta salts possess the same properties as the corresponding compounds of oleic acid.

"In order to determine the result of the action of nitrous acid on this acid, we instituted the following experiments.

"A portion of the acid, partly oxidized by the air, was slightly warmed to render it completely fluid, while a rapid current of nitrous acid gas was conducted through the liquid. The product, after being allowed to stand a week in a well-closed vessel, yielded, on recrys tallization several times repeated, an acid which melted at 37-38° C., was unchangeable in the air, and very soluble in alcohol, separating from the solution in a crystalline form.

On analysis, the following results were obtained:

"Hence this acid is an isomeric modification of the hypogaic acid; we have proposed for it the name of Gæidinic acid.

"Gaidinic ether is a colorless oil, soluble in alcohol and ether, which solidifies at low temperatures, and can be distilled without decomposition.

"Gaidinate of potassa is easily soluble in water and alcohol, and can be obtained in pearly crystalline scales.

"Gaidinate of baryta is a white powder, insoluble in water, more soluble in alcohol.

"Gaidinate of copper is a green powder, with difficulty soluble in water or alcohol, which melts before decomposition.

"Gaidinate of silver is a flocky precipitate, insoluble in alcohol or water, soluble in ammonia, and which is readily blackened on exposure to the light.

"On comparison of this new acid with elaidic acid, the product of the action of nitrous acid on oleic acid, we find a perfect correspondence in their properties, and also that the relation between the properties of hypogæic and gæidinic acids on the one hand, and oleic and elaidic acids on the other, is quite similar.

"The oleic and hypogæic acids are both, as we have seen, readily oxidized on exposure to the air, as are also the ether compounds; and farther, neither the acids themselves, nor their ether compounds, can be distilled without decomposition.

"On the other hand, the elaidic and gæidinic acids are both unchangeable in the air, as well as their ether compounds. And they and their ether compounds can be distilled without undergoing decomposition. These acids also possess higher melting-points respectively than the oleic and hypogæic acids, although we observe here the remarkable distinction, that, while accompanying the transformation of oleic acid into elaidic acid there is an elevation of 31° C. in the melting-point, the same transformation of hypogæic into gaidinic acid produces a change of but 4° C. in the melting-point.

"The correspondence between the gæidinic and elaidic acids is also further established by the relation between their melting-points. They differ by C, H, in constitution, and their melting-points differ by about seven degrees. As Heintz has shown in regard to the other series of fatty acids, a difference of from 7° 10° C. in the meltingpoints corresponds to a difference of C, H, in constitution; this rule holds good within certain limits so far as the melting-points have been accurately determined.

"These results, then, show that, under the influence of nitrous acid, hypogæic acid behaves in a manner precisely similar to that which characterizes oleic acid under the same circumstances.

"Farther, as the results of our investigation have proved, sebacic acid is one of the products of the dry distillation of hypogæic acid. Thus, that correspondence between the characteristic properties of these two acids which we should have a right to expect with two bodies standing near to one another in the same series, does not fail to hold good in every important respect. And this result is interesting, as no other member of this series of acids which has yet been discovered has yielded such satisfactory results.

"It is to be hoped, that further investigation on this series may develop a more complete correspondence between its members;-for, as they now stand, there is hardly sufficient resemblance in their properties alone to suggest a classification of all of them together. The principal reason for this classification being founded in their constitution alone."

Professor Agassiz said, that, in the course of his recent studies of the Turtles, he had been anxious to ascertain whether the different stages of embryonic development, and the different orders of this class, corresponded with the different stages

of geological succession. He was satisfied that the tracks in the Potsdam Sandstone and the Trias, attributed to these animals, were not made by them. The earliest remains of Turtles were found in the Jura, and they are of the fresh-water type. Now the order of position among Turtles places marine types lowest, next fresh-water, and last land Turtles. There was a want of correspondence with the geological succession. From the descriptions of these specimens, and his own recollection of them, however, Professor Agassiz was satisfied that these fossils present a synthetic type, like the Crinoids among the Radiata; showing characteristics belonging to several types. A similar instance he had found among the living species of South American Turtles, from Brazil, the Podœnemyds; which, although belonging to the freshwater type, yet present certain characters in the formation of the temporal region very similar to those of marine species, constituting a true synthetic type. Professor Owen obtained from the Chalk the next geological species which had been discovered, and they belong to the Chelmians, with some characters of the marine species, but not the general form,another synthetic type. Professor Agassiz did not regard these forms as presenting true exceptions to the law of correspondence between geological succession and the grade of development in living species, but only as evidence of the existence in past ages, as well as the present, of what he had called synthetic types.

Professor Horsford announced a new and convenient method of determining the value of saltpetre for the manufacture of nitric acid, by ignition with sal ammoniac.

Four hundred and thirty-fifth meeting.

January 28th, 1857. STATED MEETING.

The PRESIDENT in the chair.

The Corresponding Secretary read a letter from Manuel J. Johnson, of the Radcliffe Observatory, Oxford, accepting his election as Foreign Honorary Member.

Hon. Robert C. Winthrop exhibited a piece of the submarine telegraph cable, by which it is proposed to connect Europe with America.

Dr. Hayes remarked, that the copper wire in the centre, with its gutta-percha envelope, will be protected from all action of the salt water by the sulphurizing action of the sea. This would convert the outer layer of iron wire with which the cable is invested into an impervious sulphuret of

iron.

Dr. Charles T. Jackson exhibited a terrestrial globe, showing by colored sections De Beaumont's Reseaux Pentagonales, by which he explained his theory of the elevation of mountain chains.

Professor Agassiz commented upon De Beaumont's theory as being extremely beautiful and ingenious; in it the whole earth is likened to an immense crystal, formed by the cooling of the heated mass, the mountain ridges appearing on the lines of greatest resistance to shrinkage. He stated, that there was a singular coincidence between the number of distinct systems of Fauna, as made out by naturalists of the present day, and the geological systems of De Beaumont. These are each from fifty-five to sixty in number.

Dr. Hayes exhibited specimens illustrative of his remarks at the previous meeting on the action and products of vol

canoes.

Dr. Holmes said that he had recently observed an unusual anatomical fact, viz. the power of voluntary motion of the ear in a man. This is of extremely rare occurrence. The individual in question was able to draw backwards and upwards either or both ears, with considerable force, to the distance of from a quarter to half an inch; and this was a natural movement whenever he listened intently.

In answer to an inquiry from Dr. Holmes, Dr. Hayes explained the action of gas stoves in the generation of heat. The following gentlemen were elected Resident Fellows, viz.: :