This colouring matter, which is wholly superficial, and of different degrees of lustre, is due to an incrustation of the black oxide of manganese, and occurs independently on almost every variety of

stone.

In Jameson's Edinburgh New Philosophical Journal, for July 1851, Dr John Davy calls attention to somewhat similar incrustations in England, of which he says as follows: "Though always superficial, in one spot the incrustation is so thick as to be available for use; and in this instance the black oxide of manganese acts as a cement, forming a bed of conglomerate, several feet thick. Whence this incrustation is derived, or how produced, is not obvious. Restricting the view to the spots where it occurs, it might be supposed to be a deposit from running water. But when it is seen that the colouring matter is not to be detected on rocks in situ, the fixed rocks in the course of the stream, the idea ceases to be tenable, and the inference seems to be unavoidable, that the sand, pebbles, and stones, so coloured, have been incrusted with the oxide before they had been carried down to the spot where they are found loose, or when in the form of conglomerate, that the cementing oxide has been brought by water exuding from some rock or stratum containing manganese in a minor degree of oxidation, and acquiring the higher degree by the absorption of oxygen, and at the same time the cementing quality." Dr Davy also infers that manganese exists in the vicinity of these incrustations in large quantities, and advises special inquiry in search of it.

Before the publication of the article referred to by Dr Davy, the subject of these incrustations had attracted the attention of Dr A. Hayes of Boston and myself, and we believe the following to be a full and satisfactory account of the origin of this phenomenon :

The manganese exists in almost all the igneous and metamorphic rocks of New England, and I may say in other parts of the world, generally as a double carbonate of lime and manganese. When the waters of the springs, brooks, and rivers, flowing over these rocks, become changed with soluble organic matter, in the state of crenic, apocrenic, or humic acids, drained into them in consequence of rains or inundations, from swamps and peat meadows, the carbonates of lime and manganese enter into solution. At such times manganese may generally be detected in these waters, as has been done by Drs C. T. Jackson, A. A. Hayes, and others. When the water holding manganese in solution becomes broken and thrown up in the sage of falls or rapids, consequently exposing it to the influence of the atmosphere, the manganese passes from a low state of oxidation to the insoluble peroxide, and is deposited for a considerable extent upon the rocks and pebbles below. It will thus be found upon examination, that at intervals in the bed of the stream, the stones are completely blackened or discoloured, while in the other places no such depositions exist. Beautiful examples of this phenomenon may be

the

pas

seen at some points on the Merimac River, and indeed in almost every rivulet in New England.

I have also noticed similar depositions between the divisional strata planes of sandstones in the valley of the Connecticut, thus shewing, that apparently the same agencies were at work during the deposition of these rocks as at the present day.

2. On the existence of Organic Matter in Stalactites and Stalagmites, forming Crystallised and Amorphous Crenate of Lime.

In the eighth chapter of Liebig's Agricultural Chemistry, edited by Playfair, there is given the result of some examinations of stalactites, from caverns in Germany, and from the vaults of old castles upon the Rhine, made with the view of ascertaining the fact of the presence or absence of organic matter in these bodies, either combined or uncombined.

The result may be stated in the words of the author, Professor Liebig. The stalactites from the caverns "contain no trace of vegetable matter, and no humic acid, and may be heated to redness without becoming black. In the stalactites from the vaults and cellars of old castles," he says, 6: we could not detect the smallest traces of humic acid." There could scarcely be found a more clear and convincing proof of the absence of the humic acid of chemists, in common vegetable mould." Under the term humic acid, Professor Liebig undoubtedly means to include all those organic acids arising from the decomposition of vegetable matter, and which have received the names of crenic, apocrenic, geic, and humic acids.

Having been informed by Dr A. A. Hayes of Boston, that he had, in numerous examinations, arrived at results directly opposed to those of Professor Liebig, I was induced, at his suggestion, to make an examination of a large number of stalactites and stalagmites, obtained from various localities, with reference solely to the presence or absence of organic matter in these bodies.

The specimens examined were all from caverns or rock formations, and were obtained from various parts of the United States, from Trieste in Austria, Malta, and the Sandwich Islands. In colour, they varied from an almost pure white, to red, yellow, and brown, of different shades; and in crystalline character, from a structure resembling Arragonite, to a variety entirely wanting in symmetrical arrangement, or a mere incrustation. The specimens were dissolved in diluted hydrochloric acid, the flocculent matter separated, collected and washed, boiled in caustic potassa, carbonate of ammonia, or carbonate of soda, and then tested in the usual way for crenic and apocrenic acids. by acetate of copper and carbonate of ammonia. In all the varieties, with one exception, abundant flocculent organic matter was separated, which, on testing, gave evidence of crenic acid in considerable quantities, with doubtful traces of apocrenic acid. The excep

VOL. LII. NO. CIV.-APRIL 1852.

tion alluded to was the specimen examined from Trieste, which did not afford any appreciable flocculent matter, on dissolving in acid. The greatest quantity of organic matter was found in stalactites of a deep yellow colour, highly crystalline and uniform in character, and in the portions examined perfectly homogeneous, and free from layers or intervening bands, indicating different periods and changes in deposition. As the presence of iron could not be found in the acid solution, it is inferred that the colour of these yellow stalactites must be owing, in great part, to combined organic matter, existing as crenate of lime. In specimens, like the spar ornaments from the Rock of Gibraltar, with which all are familiar, the colouring and delicate shading is also probably due to organic matter.

Dr Hayes informs me that he has also found organic matter in Arragonite, in sufficient quantity to separate in flakes, while the specimen was dissolving in acid.

From these statements it must, I think, be inferred, contrary to the view of Liebig, that organic matter does exist in stalactites generally, as an acid combined with the lime, and imparting to them their various colours. I would by no means call in question the accuracy of the experiments of Professor Liebig, further than that, as far as my observations extend, crenic acid in the presence of lime, and combined with it, passes over like oxalates, upon heating, into carbonates, without perceptible blackening.

It may be here added, that Professor Johnston of England describes a compound of alumina with crenic acid, occurring in caves of granite upon the coast of Cornwall. This mineral has received the name of Pigotite, and is observed in places where the surface-water trickles down over the granite rocks. From this it may not be inappropriate to apply the term crenite to those lime formations in which crenic acid occurs in considerable quantities.

Results similar to those announced above, have been obtained by Dr C. T. Jackson, as well as by Dr Hayes of Boston. Dr. J. Lawrence Smith informs me, that he has frequently met with crenic acid in lime concretions from Asia Minor, and its existence in stalactites was also announced by Dr Emmons of Albany, some years since. My results can therefore be considered but as the verification of those obtained by others.

Obituaries of Oersted, Morton, and De Savigny.

1. Hans Christian Oersted.

The name of Hans Christian Oersted, the discoverer of electro-magnetism, has been added to the long list of those whom continental science has recently been called upon to

mourn.

It has been truly said of him, that the position which he occupied in Denmark was very similar to that of Humboldt in Germany. He was the philosopher, man of science, the scholar, the kind friend of youth the judicious counsellor of age,-one whom monarch and citizen alike delighted to honour. Oersted was born August 14, 1777, in Rudkjöbing, a small town on the Danish island of Langeland. The poverty of his parents and the isolation of their little village were alike unfavourable to the attainment of a thorough education. But Oersted, like many of his predecessors in the same path, learned for himself the elements of knowledge, and especially arithmetic, from old school-books which fell in his way, and taught his brother Anders, who was a year younger, all that he had thus acquired for himself. And like the brothers Humboldt, the brothers Oersted seemed in after life almost to divide between themselves the realm of human knowledge. While in each case, one brother followed the paths of actual science, and adorned the university and the academy,—the other rose to equal eminence in the other division of human knowledge, and finally became minister of state.

Oersted came to Copenhagen in his 18th year, and devoted himself to his studies with intense zeal. His fellow-student, Oehlenschläger, afterwards the celebrated poet, was at this time almost the only person who shared his friendship with his brother, and the intimate friendship thus begun continued undiminished and uninterrupted till dissolved by death.

In 1799, Oersted published his inaugural dissertation on the "Architecture of Natural Metaphysics," (Architectonik der Naturmetaphysik). This treatise shews that, even at that period, his mind was deeply imbued with tastes and sentiments similar to those which characterise the last writings of his life.

At this time he proposed his new theory of the alkalies, a theory which was afterwards universally adopted. In 1800, he was appointed adjunct in the medical faculty of the University, and began to lecture on chemistry and the philosophy of nature.

This was the year in which Volta discovered the battery which bears his name; setting this discovery, as Moller has admirably said, like a milestone at the close of one century

and the beginning of the next. All Oersted's energies were immediately enlisted for the new field of research thus opened, and he immediately detected the true law of the decomposition of salts. From this time forward he dedicated himself solely to the career of an investigator, and in the pursuit of his studies visited almost all parts of northern Europe.

His subsequent life is well known to the scientific world. In the year 1820 he discovered the magnetic influence of electricity, thus founding the science of electro-magnetism, and in fact first opening that new course of research into the mutual relations of the several energies of nature, which is still pursued with such brilliant success, yearly leading to more and more astonishing results. Without the discoveries of Oersted, where would have been those of Ampère, Arago, Faraday, Seebeck, and Melloni? In 1814 he established a magnetic observatory at Copenhagen, but has since that time devoted himself to those sciences which spring from the mutual relation of the material and spiritual worlds. His books on "The Spirit in Nature," "Natural Science and Spiritual Culture," "Natural Science in its relation to Poetry and Religion,"must be and continue classic works, whatever may be individual views of the correctness of their philosophy. The Bishop of Seeland has very recently published a severe attack upon Oersted's views, occasioned by the publication of his "Geist in der Natur." But although Denmark has been one of the last continental nations to learn how little our knowledge of the truth is advanced or facilitated by contests between theologians and men of science, the reception of Bishop Mynster's book shews that the great fact -that the true interpretation of revelations through moral and through physical media, must necessarily coincide, is now at last appreciated in Denmark also.—(Professor Silliman.)

2. Dr S. G. Morton, author of the Crania Americana and

Crania Egyptiaca.

With sadness we record the death of an eminent man from the ranks of American science, Dr Samuel George Morton of Philadelphia. He died on the 15th of May last, in his