to fall. The precipitate weighed 175-2 gr. This he considers equivalent to 28 gr. of carbonic acid. It is in reality equivalent to 28-7 gr. Thus these two analyses corroborate each other.--(See Gilbert's Annalen, vol. xlix. 412.)

II. Iodine.

Lampadius has observed that iodine dissolves with great facility in sulphuret of carbon, and gives it a dark reddish brown colour. One grain of iodine gives a deep colour to 1000 gr. of this liquid. Hence he recommends the sulphuret of carbon as an excellent reagent for detecting the presence of iodine.

III. Analysis of the Tourmalin.

I mentioned in the number of the Annals of Philosophy for last July, that boracic acid had been detected as a constituent of the tourmalin. This discovery was announced by Lampadius in March, 1818. It was made, he says, in his laboratory, by Mr. Breithaupt and himself. Since that time, the tourmalin has been examined by Dr. Gmelin, of Tubingen, with the express object of verifying the discovery of Lampadius. But hitherto his efforts to detect the presence of boracic acid have been unsuccessful. He had repeatedly analyzed the tourmalin in Berzelius's laboratory, and had always met with the same loss as had occurred to Bucholz.

IV, Phosphate of Iron.

M. Vogel, of the Academy of Sciences at Munich, has made a set of experiments to determine the composition of the different phosphates of iron. Native prussian blue (as it is called) he found composed of

Artificial protophosphate of iron he found composed of a dis

to The perphosphate of iron he found a compound of bed sw

38

$99

.... ....

It is obvious from the equivalent numbers which I have added

to these analyses, that they neither agree with each other, with the preceding analyses of the phosphates by Berzelius, nor with the weight of an atom of phosphoric acid as deduced from my experiments on phosphuretted hydrogen gas. Chemists have not yet hit upon an unexceptionable mode of analyzing the phosphates. Further researches are wanting to put us in possession of the true constitution of these bodies.

V. Meagre Nephrite.

There is a green coloured mineral which occurs likewise at Hartmannsdorf, the specific gravity of which is 2-392. It has been considered as a variety of nephrite, and distinguished by the name of meagre nephrite. But from the analysis of Zellner, there is reason to conclude that it is nothing else than an impure variety of quartz. He found its constituents as follows:

1

(Gilbert's Annalen der Physik, lix. 181.)

ad (halls VI. Professor Mohs' Observations on Cornwall.

The following extract of a letter from Professor Mohs to Mr. Privy Finance Councillor Blöde, has been published in Gilbert's Annalen der Physik, lix. 217. I am induced to translate it, because I had the pleasure of meeting with Prof. Mohs pretty frequently last summer while in Scotland, and had every reason to form a very high opinion both of his abilities and his mineralogical skill. He has been appointed the successor of Werner at Freyberg, and his reputation as a mineralogist is not inferior to that of any person whatever in Germany.

"In all Cornwall I could observe no greywacke nor greywacke slate. The killas is an intermediate substance between mica slate and clay slate, very similar to some varieties which occur at Johann-Georgenstadt. It alternates here and there with beds of a porphyry, whose basis is an intimate mixture of felspar, quartz, and mica. In some places it alternates with beds of greenstone and limestone; and contains granite in that very remarkable relation which I described in a preceding letter (namely, that which the English mineralogists, and particularly the Huttonians, call granite veins). I believe I have seen all the remarkable appearances of this kind. They agree exactly with

the stockwerke at Geyer. St. Michael's Mount, near Penzance, is a very remarkable mountain, which exhibits the relations of these stockwerkes in a striking manner, as the same veins pene. trate into both, and contain the very same minerals; namely, tinstone, apatite, copper pyrites, &c..

"Similar veins, equally remarkable, occur at Conglure near St. Austle, and at Cliggepoint, not far from St. Agnes, At the latter place are some of the celebrated granite dikes, unconformable masses in killas, and without doubt of the same age with the rock in which they occur. Dartmoor is a desert and bare and almost uninhabited place, in which the most interesting thing which I observed is the Zinnseifen. The geological relations of Cornwall are very simple, though for want of a sufficient number of accurate observations they have not yet been fully made out. My astonishment at the number, the richness, the extent, and the quality of the tin and copper veins, is not yet over. When I saw the first heap extracted from a vein, I conceived that it must have been obtained from a bed, and only satisfied myself by actual inspection that the ore was really extracted from a vein.

"An object, on which several geologists in England employ themselves in preference, is the study of the formations lying above the chalk. To see them, we went to the Isle of Wight. These newer formations are very remarkable. But the separa tion of the fresh water formations from each other depends merely on the loose stones found in the different beds, and seems to be merely a conclusion which has been borrowed, perhaps, on too slight grounds from the French."

VII. Remarkable Mineral Spring in Java.

Mr. Clarke Abel, in his "Narrative of a Journey in the Interior of China," lately published, gives the following account of á mineral spring in Java, which I am induced to transcribe, though the account is unavoidably incomplete, because the quantity of sulphuretted hydrogen gas which passes through the water seems much greater than has ever been observed in any other part of the world.

"These springs are in the midst of a jungle on the right hand side of the road from Sirang to Batavia, and the country for many miles round is a perfect flat. On approaching them, I smelled the sulphureous gas, which they throw out in immense quantities. They are situated on a piece of barren ground, about 50 yards square, composed of a hard rock, which seemed to have been formed by deposition from the springs. In the midst of this space were several small pools of water in great commotion. They so exactly exhibited the appearance of boiling, that I immersed my hand in them with considerable caution, and scarcely credited my feeling when I found them of the temperature of the surrounding atmosphere. The central pool was the largest, having an area of eight or ten feet. The water

bubbled up from several parts of its surface. For the sake of ascertaining the cause of these phenomena, I walked in, and discovered its greatest depth to be about three feet. Its bottom was formed of rock, broken into masses of different shapes. On searching immediately under the place where the agitation of the water was most violent, I found a small funnel shaped aperture, the lower part of which was not more than an inch in diameter. Through this sulphuretted hydrogen gas rushed up in such quantity and with so much force, that I could with great difficulty keep my hand close to its orifice."

"On examining the sensible properties of the water on the spot, I found it to be of a dirty white colour, containing a considerable portion of earthy matter in suspension. The smell was that of Harrowgate water. The soil on the margin and at the bottom of these pools is soft, and of a yellowish-grey colour on the surface; but a few inches beneath, it becomes of a rocky hardness and red. At the distance, however, of two or three feet from the pools, the surface itself is equally hard, but of a blue colour, and bearing evident marks of having been at some distant period the seat of agitated water. A loud bubbling noise is distinctly heard on placing the ear close to any part of the barren spot in which they are situated. The natives believe that the water possesses medicinal properties, and that it is especially efficacious in cutaneous diseases."(P. 40.)

VIII. Chinese Stone Yu.

Many of my readers are aware that there is a stone of a greenish white colour, and considerable hardness, to which the Chinese give the name of Yu, and which they prize more than any other stone. It is said to occur in the form of nodules in the bottom of ravines and in the beds of torrents, and in larger masses in the mountains themselves, especially in Yunan, one of the most northern provinces of the empire. It has been long known in this country under the name of Chinese jade or nephrite; but Prof. Jameson, in the last edition of his Mineralogy, vol. i. p. 505, assures us, that it is prehnite. The following are the characters of this mineral as given by Mr. Clarke Abel, in his Narrative, &c. p. 134.

"Its colour is greenish white, passing into greyish green and dark grass green. Internally, it is scarcely glimmering. Its fracture is splintery; splinters white. It is semi-transparent and cloudy. It scratches glass strongly; and is not scratched by, or scratches, rock crystal. Before the blow-pipe it is infusible. without addition.

1. Whitish green, marbled with dark green 2. Dark green variety.

Sp. gr. 3.330

3-190

3. Whitish green variety, same as No. 1.

3.400

4. Light-coloured greenish white variety.

2.858

The specimens, of which the specific gravities are as above,

were all, except the last, furnished me by the kindness of Sir George Staunton. The last is precisely of the same nature as the sceptre sent to his Royal Highness the Prince Regent, and was put into my possession for the purpose of examination by the Hon. Mr. Amherst, to whom it was presented by one of our

attendant Mandarins."

The only part of this description which cannot be reconciled to prehnite is the infusibility before the blow-pipe. The specific gravity of the fibrous variety of prehnite is 2.901, its hardness is nearly the same as that of the Yu; and though its fracture is always fibrous, yet I can conceive it to be described by a person not familiar with the external characters, as having a splintery fracture, which is not altogether erroneous. The infusibility before the blow-pipe seems to separate the Yu both from prehnite and from nephrite to which Mr. Abel refers it..

IX. Temperature of the Bottom of the Sea.

The following are all the observations on this interesting subject which Mr. Clarke Abel preserved. The rest were lost by the unfortunate shipwreck of the Alceste. The observations in the following table were made in the Yellow Sea.

July 23. 8a. m. 350 1'123° 46' 11 miles. 40 760 749 24.12 m. 36 24 122 59

650

15 75 71

67

Mr. Abel states an experiment on this subject by Captain Wauchope of his Majesty's ship the Eurydice, which deserves to be stated here as one of the most striking and instructive upon record. Within a few degrees of the equator during a calm, Capt. Wauchope put his apparatus overboard, and allowed it to descend till it had carried out 1400 fathoms of line. But he estimated the perpendicular depth at 1000 fathoms. The temperature of the surface was at 73°. On drawing up the instrument, he found the inclosed thermometer marking 42°—a difference of temperature between the surface and given depth of 31(Ibid. p. 347.) amigolobes le monddel Jadi Borobiente

os ibomenrud ms Ulmin from a Corks Treetspils ibi! »

This substance was collected by Dr. Leach from la decayed cork tree on the estate of Marriott, Esq. of Wimbledon.