carburet of potassium, producing thereby cyanogen and cyanuret of potassium. This explanation accords with the experiments of Defosse.

Mr. Leigh read a communication "On a new product obtained from Coal Naptha."-The substance described was obtained in the course of some investigations on an oil which Mr. Leigh discovered about three years and a half ago, as the result of a mixture of nitric and sulphuric acids on purified coal naptha. In their behaviour with potassa, both in aqueous and alcoholic solution, the crystals now brought under the notice of the section by Mr. Leigh have much analogy with the oil (like that of bitter almonds) obtained at the same time with them. The oil when extensively exposed to the action of hydrogen, becomes a crystalline solid, having much the same appearance as these crystals. It is probable the crystals differ from the oil in containing a quantity of oxygen. Mr. Leigh had made no analyses of these compounds.

Mr. Croft read the next paper, "On Kakodylic Acid, and the Sulphurets of Kakodyl," by Professor Bunsen, of Marburg. In the present paper, Professor Bunsen examines the higher stages of oxidation of kakodyl, and the sulphurets corresponding to them. He finds that, by the oxidation of alkarsin, either by the direct action of the air, or by means of oxide of mercury, kakodylic acid is formed; but there is also an intermediate oxide, which cannot be obtained in a state of purity, which seems to be similar to the hyponitric acid, and to be a combination of kakodylic acid with the oxide. Kakodylic acid crystallises out of alcohol; its composition is C H As, O3 + HO, this atom of water being constitutional, and only to be replaced by a base; it is soluble in water, but not in ether. A very remarkable fact with respect to this body is, that the poisonous properties of the arsenic seem totally annihilated; eight grains administered to a rabbit exerted no poisonous action. Kakodyl combines directly with sulphur, forming the proto-sulphuret which has been already described. This compound takes up another atom of sulphur, and produces the bisulphuret. There appears also to be a tersulphuret analogous to kakodylic acid; Professor Bunsen has not, however, been able to obtain it in a pure state. From the above results, it appears, that kakodyl is precisely similar in its behaviour to some simple metals, and the formation of kakodylic acid by direct oxidation, is in exact opposition to Dumas's theory of substitution.

Dr. Schunk read a paper "On the compounds of Carbon and Iron," by Dr. C. Bromeis.-Dr. Bromeis analyzed various kinds of iron by burning them in a tube, with a mixture of chromate of lead and chlorate of potash. The combustion is conducted exactly like an organic analysis, and is the method invented by Regnault. An important point in the determination of the carbon in iron, is to ascertain the proportion of carbon in a state of combination, in contradistinction to that which is mechanically mixed with the metal.

Dr. Bromeis effected this by dissolving the mixture in muriatic acid; the carbon, in chemical combination, unites with hydrogen, and forms carburetted hydrogen, while the carbon in mechanical mixture, takes no part in the action, but remains unaffected, and . may be accurately determined. This quantity being subtracted from the whole carbon obtained by combustion, affords a means of estimating the quantity in chemical combination. Dr. Bromeis found in crystalline white cast iron, 3.8 per cent. of carbon. But as some white cast iron has been found to contain 4.2, or even 5.3 per cent., Dr. Bromeis considers that manganese may be substituted for it; he sometimes found as much as 7 per cent. of this metal. It appears, therefore, that neither common nor white cast iron are polycarburets of determinate constitution. In white cast iron Dr. Bromeis found only 0.5 per cent. of mechanically combined carbon, in other kinds nearly 1 per cent., and in grey cast iron, 2.3 per cent. Hence it follows, that the chemically combined carbon amounts only to 0.9 per cent.: Karston found 0.85 per cent.; cast steel, according to Gay-Lussac and Wilson, contains 0.93 per cent. of carbon. Bromeis found in hard cast steel 0.97 per cent. Grey cast iron may be considered as a mixture of very impure cast steel with carbon. This may possibly be the cause that it can be so easily hardened on the surface.

The next paper was by Mr. Richardson, "Contributions to the history of the Magnesian Limestones."-The author, considering the great importance of the magnesian limestones, both to the manufacturer and agriculturist, conceived that an account of their composition might prove acceptable. He examined the various limestones systematically, according to the excellent arrangements of Professor Sedgwick, and collected the results of his analyses in a tabular form. The insoluble residue of the specimens subjected to analysis, contained, in every case, organic matter. The analyses proved a very great variation in the quantities of lime and magnesia; a fact which will not surprise the chemist when he considers that they are isomorphous, and therefore capable of mutual replacement. Mr. Richardson argued, that the deposition of the lime and magnesia must have been effected simultaneously, from the fact of layers of limestone existing above and below the magnesian limestones, in which layers no magnesia can be detected. He was inclined to ascribe their deposition to the influx of waters holding chloride of magnesia in solution, which, meeting with calcareous matter held in solution by an excess of carbonic acid, robbed it of that excess, and the two carbonates of lime and magnesia fell together.

Dr. Kane remarked that Dr. Apjohn had examined some Irish Dolomites of the magnesian limestones, and had found the carbonates of lime and magnesia in atomic proportions. Mr. Croft stated, that he had observed the same fact in analyzing specimens from Saxony and other countries.

Mr. W. Snow Harris then made a Report on the Meteorological

Observations made at Plymouth last year. He stated that, at the close of 1842, he should be able to revise (and bring to the next meeting of the association) the results of the series of meteorological observations continued hourly, night and day, without material interruption, during ten years. He now submitted only a general discussion of five years' observation of the barometer, during the years 1837 to 1841, both inclusive, and some observations and experiments on the wind, made with Professor Whewell's anemometer. The observations were made at a height of seventy-five feet above the level of the sea, and were produced to 32° Fahrenheit. He exhibited a chart, showing the lines resulting from the means in each of these years, and also the mean of the whole five years, and noticed the surprising coincidence in the general character of all these lines, and the very few and small deviations they presented: a remarkable result, considering the frequent atmospheric disturbances to which these latitudes are liable. The mean pressure of the six years corresponded with that already obtained. The line of mean pressure occurred between the hours of 1 and 2, and between and 8 A.M., and again between 12 and 1, and between 6 and 7 P.M. The hourly maximum pressure was at ten o'clock morning and night, being with only one exception, the uniform result for six years. The hourly minimum pressure occurred at 4 A.M. and P.M., being the uniform result for six years, without any exception. The line of mean pressure was crossed four times in the twenty-four hours; and thus was realized, in the midst of atmospheric disturbances of very considerable amount, that effect, termed "horary oscillation," which was first observed by Baron Humboldt, in tropical climates. Mr. Airy, to whom these observations were submitted, seemed to think, that but little more could be effected by a further continuance of them, after the close of this year. There had been 48,000 hourly observations on the atmospheric pressure, and 87,000 hourly observations on the temperature; and he trusted these would not be preserved merely in the fragile form of MS., but placed at the disposal of the scientific world, After explaining the construction of Whewell's anemometer, he said, that when the pencil tracing the integral effect of the wind, moved at the rate of one-tenth of an inch per hour, the current of air at the same time moved at a mean rate of eleven feet per second. He (Mr. Harris) had, by means of ' this instrument, endeavoured to arrive at something like an approximation to the velocity and direction of what he believed would amount to a trade wind. He had a table of results which gave the mean velocity of the wind (in feet per second) for each month of the year, viz:

So that the mean velocity of the wind during one year (leaving the direction out of the account), was about nine miles per hour. If the mean velocities arrived at in this table were diminished and made proportionate to the whole length of the wind, we should then have something like a general idea of the velocity of the aerial current as deduced from observation and inquiry. Then, according to Mr. Whewell's method of taking the observations (which he was persuaded was the only true method), in the latitude of Plymouth, they had something like a trade wind, setting in from southerly to northerly points of the compass at a mean velocity of four and a half to six miles in the hour. This was something like a definite result in meteorology; for no person before had ever attempted to discover the direction and velocity of the wind in its rate per hour, setting in a given direction. In these statements he had been dealing only with mean results.

Mr. Howard hoped that Mr. Harris would not think of discontinuing these observations until at least the cycle of eighteen years had been completed.-Dr. Scoresby would wish that observations with the anemometer should be tried on the sea, in order to get rid of the friction and other causes of retardation which affected the current of air over the land.-Col. Sykes believed that the hours of maximum and minimum mean pressure observed by Mr. Harris at Plymouth, would be found nearly, if not exactly, the same as those observed in India at an elevation of 2,000 feet above the sea, and those observed in Mexico by Humboldt, 10,000 feet above that level. Col. Sabine said, he had that morning received a very important letter from Prof. Wheatstone, which had been laid before the Committee of the Section, and which they wished should be communicated to the Section previous to being transmitted to the Committee of Recommendations. It contained a proposal to make, for the Observatory at Kew, an apparatus which should record the operations of all meteorological instruments, so as to effect a great saving of cost. One of the instruments was for measuring the force and direction of the wind, and was capable of being sent up in captive balloons, so that the currents, to a height of 8,000 or 10,000 feet, might be carefully examined. It was stated in the letter that, all attempts to make self-recording thermometers, barometers, &c. by mechanical means have hitherto failed, because the mechanical force exerted by the rise of the mercury in the tubes is insufficient to overcome the friction of the attached mechanism, and only very in

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accurate indications can be obtained. The principle, however, observes Mr. Wheatstone, which I employ in my meteorological telegraph, viz. the determination (by means of a feeble electric current) of any required mechanical force, by the mere contact of the mercury in the tube with a fine platina wire, enables all these difficulties to be overcome. propose, therefore, that such an instrument, the cost of which I estimate will not exceed £50, shall be constructed under my direction, for the Richmond Observatory. If, after a few months' trial at the Observatory, it shall be found to succeed, as I confidently expect it will, a great impediment to the advancement of meteorological science will be removed. Persons in almost every locality may be found who would not object to devote a few minutes per day to prepare such an instrument for use, but who would find it impossible to give the requisite attention to make hourly or half-hourly observations them-selves. Col. Sabine said, Mr. Bache, of Philadelphia, has requested me to explain the reasons which have prevented him from completing the Report on the Meteorology of the United States, which has been first called for, and which, at the meeting of the British Association at Newcastle, Mr. Bache, being then present, was requested to prepare. But the task of providing funds by private subscription in the United States for the support of the system of magnetical and meteorological observations recommended by the association (which is elsewhere provided for as a national work) has been undertaken by by Mr. Bache, in addition to that of superintending its establishment and progress. Being thus occupied, Mr. Bache has found himself unable to devote the necessary time and thought to the report.

Mr. Nasmyth prefaced his paper "On the Application of the Law of Definite Proportions to the Stratification of Clouds," with the remark, that he was first led to speculate on this subject, by observing the arrangement of clouds in fine weather, when, towards the horizon particularly, they may be seen extended in parallel bands or stripes. He conceived that the excess of vapour floating in the atmosphere beyond what the air could combine with, formed clouds; and that the air, in each electrical state, was capable of sustaining a definite proportion of vapour, and consequently, that the clouds of one class or description, floated (in what might be called a plane of equal electricity) at a uniform distance from the earth.

Prof. Bessell, Königsberg, made a communication "On the Astronomical Clock." Having ever been of the opinion, that that indispensable instrument to the astronomer, the transit clock, could only acquire perfection if the pendulum, separated from the works, were made to vibrate in equal time, whatever the temperature and the arc might be, he would submit, whether the expeditious method of coincidences might not be employed for checking the pendulum in both respects. The pendulum, apart from the clock, being suspended from the wall, a clock, taken out of its case, might be placed