ART. I.-Philosophical Transactions of the Royal Society of London. For the Year 1810.—Part I.

The Croonian Lecture. By William Hyde Wollaston, .M. D. Sec. R. S.

DR. WOLLASTON has in this lecture given a few observations on subjects not intimately connected. He has divided it therefore into three distinct parts, which we shall notice in their order.

Part I. On the Duration of Muscular Action.

If the extremity of a finger be inserted into the ear, a sound is perceived which much resembles that of carriages at a great distance passing rapidly over a pavement. From this fact Dr. Wollaston infers that a single effort of muscular contraction consists in reality of a great number of contractions repeated at intervals so short, that the intermediate. relaxation cannot, in a state of health, be perceptible. To produce this sound muscular action is absolutely necessary; no such sound is produced, whatever pressure is applied to the tympanum by any other agency; and a slight pressure makes the vibration more distinct than a great one, if the finger be made rigid by the forcible action of antagonist muscles.

Dr. Wollaston estimates the frequency of these vibrations at between 20 and 30 in a second. He thus describes the method he used in forming this calculation.

'While my ear rested on the ball of my thumb, my elbow was supported by a board lying horizontally, in which were cat CRIT. REV. Vol. 22, January, 1811.

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a number of notches of equal size, and about 1-8th of an ich asunder. Then, by rubbing a pencil or other round piece of wood with a regular motion along the notches, I could imitate pretty correctly the tremor produced by the pressure of my thumb against my head, and by marks to indicate the number of notches passed over in 5 or 10 seconds, observed by my watch, I found repeated observations agree with each other as nearly as could be expected; for I could not depend upon exerting the same degree of force in different trials.

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. It seems that the frequency of these vibratory motions is not uniform. The greatest number of beats was about 35 or 36 in a second; and the last was as low as 14 or 15. This curious observation deserves to be pursued.

Part II. On Sea Sickness.

We doubt whether physiologists will agree with Dr. Wellaston in his explication of this distressing affection. He conceives it to be the consequence of mechanical pressure on the brain, and that the stomach acts sympathetically. In the erect posture the blood presses upon all parts in proportion to its altitude. This is evident. But, says Dr. W. let the support be removed from the feet,

the blood would be no longer supported by its vessels; but both would fall together with the same velocity by the free action of gravity; and the same contraction of the vessels which before supported the weight of the blood, would now occasion it to press upon the brain, with a force proportioned to its former altitude.'

We do not believe this to be either physically or experimentally true. Dr. W. illustrates his position by the barometer, in which it has been observed that by the subsidence of the wave the mercury is seen to rise in the tube which contains it. We are surprised at so weak an argument from the pen of Dr. Wollaston, since it is evident, that if the mercury rises in the tube it must sink in the bason. The whole is probably owing to the motion communicated to the whole body of quicksilver making it to vibrate, or rather to undulate.

But whether the mechanical effect be or be not such as Dr. W. supposes, the hypothesis is quite incompetent to account for the phenomenon. Sickness, the same in kind, though less severe in degree, is excited by motion in a carriage on a level road. We remember to have seen a dog made sick by being carried across the Frith of Forth in a boat, when there were no waves. Simple motion, to which the

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body is unaccustomed, or a great interruption to the usual catenation of action, is sufficient to excite sickness. must rest contented with the fact; the cause will probably never be resolved upon mere mechanical principles.

Part III. On the salutary Effects of Riding, and other Modes of Gestation.

These observations, we are compelled to say, are very frivolous. Dr. Wallaston, we think, will not increase his wellearned reputation, by travelling out of the field of scientific observation, which has diverted him from pursuing medical and pathological inquiries.

11. The Rakerian Lecture for 1809. On some new electro-chemical Researches, on various Objects, particularly the metallic Bodies, from the Alkalies and Earths, and on some Combinations of Hydrogene. By Humphry Davy, Esq. Sec. R. S. F. R. S. E. M. R. I. A.

We shall follow our customary mode of analysing Mr. Davy's papers, pursuing the arrangement of the author, and condensing, as far as is consistent with clearness, the mass of information contained in his multifarious researches.

I. Some new Experiments on the Metals from the fixed Alkalies.

In this part of the lecture Mr. Davy defends his former conclusions on the metallic nature of potassium, sodium, and the other new metals against the objections which have been offered against them, chiefly by foreign chymists.

The first hypothesis he examines is that of M. M. GayLussac and Thenard, who have maintained that potassium and sodium are compounds of the respective alkalis and hydrogenes. They say that by heating strongly the olive coloured substance produced by the action of potassium on ammon a, potash is produced; moreover, hydrogen is evolved during the production of the fusible substance; and the whole of the ammonia is afterwards procured either in its proper form, or as hydrogene and nitrogene. But Mr. Davy has shewn in his former experiments that the results of this process when the operations are conducted in a refined and accurate manner, are not such as stated by the French chymists, and he has now repeated the process of distilling the olivecoloured substance, as he proposed, in a tube of platina bored from a single piece, with every precaution to avoid error.

This experiment seems decisive as to the nature of potassium, though it has not confirmed his suspicions of the convertibility of nitrogene into hydrogene.

When the distillation was performed in this manner, taking care to raise the heat very slowly, more than four-fifths of the potassium was reproduced; and very nearly the whole of the nitrogene existing in the ammonia employed, the loss of hydrogene was proportionally greater than that of nitrogene.

In these experiments a considerable quantity of black matter separates, whilst the potassium, which is reproduced in the tube is exposed to the action of water. As far as Mr. Davy has advanced in its analysis, it appears to be platina combined with a minute quantity of inatter which affords water by combustion in oxygene.

Upon the whole Mr. Davy concludes that

by the operation of potassium upon ammonia, it is not a metallic body that is decompounded, but the volatile alkali, and that the hydrogene produced does not arise from the potassium, as is asserted by the French chymists, but from the ammonia, as I have always supposed; the potassium in the most refined experiments is recovered, but neither the ammonia nor its elements can be reproduced, except by introducing a new body, which contains oxygene and hydrogene.'

Mr. Curandan has stated, that when sodium is oxydated, carbonic acid is formed, and has thence inferred that the metals of the alkalies are composed of the alkalies united to charcoal. This experiment has not succeeded with Mr. Davy. No carbonic acid is produced, except when the metal is covered by a film of naphtha; and it appears that M. Curandan must have operated upon carburets, not of potash and soda, but of potassium and sodium.

M. Ritters argues from the extreme levity of potassium and sodium, that they contain hydrogen. This however proves nothing in contradiction to direct experiment. This gentleman has stated the curious fact, that when a circuit of electricity is completed in water, by means of two surfaces of tellurium, oxygene (as in other cases) is given off at the positive surface, but no hydrogen at the negative surface, but a brown matter is separated, which he regards as a hydruret of tellurium. Mr. Davy, observing with attention these appearances, found that when tellurium is made the negative surface in water of a voltaic battery, composed of more than 300 plates, a purple fluid first separates and is diffused through the water, which gradually becomes turbid, and deposits a brown powder. The purple fluid is a compound of hydro