previously remarked several times this coincidence with rain and a sudden electrical change in clouds. I have this year had several opportunities of making the same observation. The remainder of the month, and the whole of May, was but slightly electric. The clouds rarely induced my apparatus to speak.

On the 8th of June, about 4 P. M. I had a descending negative current; rain began to fall at 5. The current suffered several negative and positive changes. The rain-drops were not affected in the same manner: they constantly gave negative indications by the electroscope. On the 11th, the commencement of a storm was positive, the middle negative, and the termination became again positive.

On the 16th, I was awakened at a quarter past 2 A. M.-a storm was raging on every side. I ran to my instruments; they indicated 80°, and a descending negative current. Some large flashes of lightning scarcely produced 10° to 15° of diminution in the deviation; at halfpast 2, the negative current still giving 70°, a very large flash occurred, the needle spun round on its axis, and settled at 80° on the other side; it stood there thirty seconds, and then returned to the 70, as before the flash. The storm passed off about three-quarters past 2, the needle returned to zero, then moved to the positive side, and rested.

In the selection of instances, I shall give the preference to the one of the 21st of July, because the cloud which I observed was of a very limited extent, and excited some hope that I might ascertain the cause of these anomalies. This cloud had passed over the apparatus for a fourth of its length before any indication was produced; at this point, a descending negative current of 4° to 5° began to take place; it increased with the progress of the cloud. Suddenly, the deviation ascended to 70°. I therefore predicted that the rain had separated from the cloud, and would shortly appear; this actually took place in a few seconds after. During the shower, the current continued negative, and was not positive till the end of it.

The showers on the 29th July gave no electrical indication.

Contrary to all preceding storms, that of the 4th August, at 2 A. M., was positive at first, and negative as it continued. The needle moved gradually towards a maximum, a flash occurred, and the

needle returned half-way; it then recommenced its ascending progress until the next flash, which reversed its motion. This progression coincided so closely with the electrical changes, that I was able to decide that they were simultaneous with the separation of the rain from the cloud. My second apparatus had its internal needle injured by the strength of the current.

Finally, the last storm, that of the 6th August, produced at least five and twenty changes. It was also negative at the commencement and positive at the end.

Though confined as the sphere is upon which I can operate in my observations, I shall continue to seize every favourable opportunity of throwing light on this obscure subject.-PELTIER.

The State assisted by Science. THE intercourse between the French government and the Académie des Sciences appears to be very frequent; and the objects are of the most interesting kind. The applications of the Academy for means, for authority, for access to documents, &c. are never disregarded, and, on the other side, no branch of the administration ever ventures to decide upon a measure in which the natural and applied sciences can furnish any information, without asking for information, or soliciting advice, from the Academy. We have already given one instance at p. 484. Here is another, demanding a more extensive range of inquiry, and an extent of laborious examination and comparison which would terrify many an F.R.S. among our countrymen, and induce him to abandon his initials rather than expose himself to be so questioned and set to work.

The Minister of Finance thus writes to the Secretary of the Academy:Sir,-The Commission directed by the Ordonnance of the King, dated the 29th March, 1836, to examine if there be any ground for altering or modifying the conditions of Article 219 of the Code of Forest-law relating to the felling of the woods of individuals, having, in the sitting of the 11th June last, taken into consideration various points in statistics, in meteorology, and administration, were of opinion that information might be usefully requested from the various ministers and public offices, from the prefects, and from the Académie des Sciences.

"The minutes of this sitting which I have before me, contain instructions to request of the Academy the solution of the following meteorological questions: "1. Are there existing in France thermometrical observations from which it can be deduced that the temperature is constant; or, on the contrary, that it varies? Does the snow lie as long on the summits of mountains as it formerly did? "2. From the earliest times described in history to the present, have the seasons of harvest, of fruit-time, and of the vintage, undergone any change? Have they not in some particular localities? Is rain more or less abundant?

"3. Is the fall of snow as great as during the last century? Is there any diminution in springs which can be attributed to the felling of woods?

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4. In districts which were formerly exempt from hail, are the effects of it injurious at the present day?

5. Has it been observed that the frequency of storms has increased since the destruction of the forests?

"6. Have inundations of rivers been greater and more sudden than before the Revolution?

"7. Has the direction of prevailing winds been changed by clearing away the woods? Are they more violent? more destructive? more insalubrious?

"8. Are the beds of rivers sensibly elevated? If they are, what is the annual amount of their rise?

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I shall be obliged by your submitting these various inquiries to the attention of the Academy and its correspondents in the departments, and to communicate the result to me."

The Academy appointed a Commission to carry the request of the minister into effect. This commission consists of MM. Dulong, Arago, Gay-Lussac, Silvestre, Girard, Mirbel, and Costaz. Easy solidification of Carbonic Acid. -Extraordinary artificial Cold. AFTER having examined, in succession, the various properties of liquid carbonic acid, its specific gravity, which is so variable that between 32° and 86° it runs through all the scale of densities, from that of water to that of the ethers, -its dilatability, four times greater than that of air itself,-the pressure, and the weight of its vapour,-its capillarity, and, above all, its compressibility, a thousand times greater than that of water, I was induced to determine

exactly the uniform and constant law, which connects these phenomena, and which, at the first glance, appear to be quite independent of each other. By means of a very simple apparatus, I can now produce instantaneously, and with economy, lumps of solid carbonic acid, weighing to oz. troy. These will probably be of some utility in experimental chemistry.

My early experiments on cold were made by directing a jet of liquid carbonic acid either upon the bulb of a thermometer, or upon tubes in which the substances intended to be exposed to the action of cold were enclosed. This mode has the disadvantages of wasting a large quantity of acid, and leaving some uncertainty as to the maximum of cold produced. The abundance and facility with which I can now obtain solid carbonic acid has furnished me with a mode of experimenting far more preferable.

The bulb of a thermometer being inserted in the centre of a small piece of solid carbonic acid, the index will, at the end of one or two minutes, become stationary, and mark -130° F. (= 162° below the freezing-point).

A few drops of ether or of alcohol, thrown upon the solidified mass, produce no appreciable modification, either more or less, in the temperature. The ether forms a mixture, partly fluid, and of the consistence of sodden snow; but the alcohol uniting with the solid carbonic acid, congeals, and produces hard and brilliant ice, of a demi-transparency. This congelation of anhydrous alcohol takes place in the state of union only; if the alcohol be preserved isolated in a silver tube, in the middle of a mass of solidified acid, it undergoes no change of form. The mixture of alcohol and solid carbonic acid begins to melt at-121° F. (= 153° below the freezing-point). Arrived at this degree, the temperature suffers no further change. So that at this extreme limit, there may be obtained a point as fixed as that of melting ice.

If, after having formed a little cup of solid carbonic acid, and about oz. troy of mercury be poured into it, the metal will be seen to congeal in a few seconds, and to continue in its new form so long as there remains an atom of solid carbonic acid; that is to say, during twenty or thirty minutes, if the weight of the cup be nearly oz. troy.

I have said that the addition of ether

or of alcohol does not increase the actual degree of cold; but by giving to the solid carbonic acid the property of wetting the bodies, and adhering more intimately to their surfaces, these substances greatly augment the frigorific effect. One volume of solid carbonic acid, upon which has been poured a few drops of ether or alcohol, can then congeal 15 to 20 times its weight of mercury. The rapidity with which the solidification of the mercury takes place, the mass which may be acted upon, (which, with facility, may exceed half a pound,) and the permanency of the change of form, (which may be maintained as long as desired, by merely taking the precaution to place the metallic button on a bed of solid carbonic acid,) induce me

to believe that this mode of solidifying mercury will henceforth be substituted for those which have been in use to the present time.-THILORIER.

Frozen Mercury.

M. DULONG exhibited lately to the

Académie des Sciences a mass of mer

cury frozen by the process of M. Thilorier, which weighed about 14lb. troy. * See p. 493.

Temperature of the Geysers.

THE temperatures of the Geysers (hot vapour-springs) in Iceland, have lately been taken with great care by M. Lottin. That of the Great Geyser, at about 80 feet deep, was found to be 257° Fahr., 45° above the boiling-point. The Small Geyser, situated close by, at about 50 feet deep, gave 232° Fahr. Water, at the surface of the ground, in a small hole, was found at a temperature of 214°.-ROBERT. Letter from Iceland, July, 1836.

Patent-Law Grievance. No. X.

THE penalties inflicted on the inventive genius of Britain during the present year, up to the 25th ult., in the shape of government stamps and fees on patents, amount to more than £42,000!

N.B. This sum has been paid in ready money on taking the first steps, and as many of the inventors are poor men, (Operatives,) and a great many others of them persons to whom it would be very inconvenient to pay at least £100 down, they have been obliged to go into debt, or mortgage or dispose of their inventions, either wholly or in part, &c.

NOVEMBER cont.

263. WILLIAM SNEATH, Ison-Green, Nott., Lace-maker; for improvements in producing embroidery, or ornaments on muslins, silks, and certain other fabrics. Nov. 28. -May 28.

264. ALEXANDER STOCKER, Bordesley Iron-works, and HENRY DOWNING, French Walls Iron-works, Birmingham, Warw., Gents. ; for improvements in manufacturing rivets, screw blanks, and other articles. Nov. 29.-May 29.

TOTAL, NOVEMBER...22.

DECEMBER.

265. DAVID NIMES CARVALHO, Fleet-st., Lond., Bookseller; for improvements in propelling or moving vessels, and other floating bodies, on water, and carriages on land, which improvements are applicable to windmills and other purposes. Dec. 3.June 3. For. Comm.

266. ROBERT ARMSTRONG, Stonehouse Devon., Doctor of Medicine; for improve

dering it more generally applicable for ments in the water-pressure engine, renraising water and other substances, and as a motive power. Dee. 3.-June 3. Lincoln's-Inn, Midda., Gent.; for ma267. MOSES POOLE, the Patent-Office, applicable to various useful purposes. Dec. chinery for a method of generating power,

3.-June 3. For. Comm.

268. JAMES CORBETT, Richmond-place, Limerick, Ireland, Professor of Music; for improvements in producing harmonic sounds on the harp. Dec. 3.-—June 3.

269. JACOB PERKINS, Fleet-st., Lond., Engineer; for improvements in steamengines, furnaces, and boilers, parts of which improvements are applicable to other purposes. Dec. 3.-June 3.

270. GEORGE SULLIVAN, Morley's Hotel, Charing-Cross, Midda., Gent.; for improvements in machinery for measuring fluids. Dec. 3.-June 3. For. Comm.