348 



that in the present experiment there was a loss of between three and 

 four inches of nitrogen to be sought in the residuum which had been 

 heated in the metallic tube. But when the tube was opened, nothing 

 was found but potash that had been fused, and a small quantity of 

 potassium sublimed into its upper part ; so that in the place of the 

 nitrogen nothing was found but oxygen contained in the potash, 

 which, together with a small excess of hydrogen, may amount to the 

 weight of the nitrogen lost. 



In other experiments five grains of the olive-coloured ammoniacal 

 pyrophorus, formed by potassium, yielded by mere heat, or by oxygen, 

 three fourths of an inch of nitrogen ; but by water they evolved one 

 fifth of hydrogen, and 3^ of ammonia, which by estimate contain l 

 of nitrogen. 



If the nitrogen is to be considered as converted into oxygen and 

 hydrogen, it must be regarded as containing much more oxygen than 

 water ; and if we do not adopt this supposition, Mr. Davy considers 

 the only alternative to be, that water is the ponderable matter which, 

 under different modifications of electro-chemical existence, consti- 

 tutes oxygen, hydrogen, nitrogen, and the nitrous compounds ; but 

 with respect to conclusions so important, and so little to be expected 

 by any analytical chemist, it appears to Mr. Davy highly unphiloso- 

 phical to decide in the present state of our knowledge. 



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

 Read November 16, 1809. [Phil. Trans. 18.10, p. 1.] 



Since the remarks, which the author has connected together on 

 the present occasion, as tending, each of them, to promote the design 

 of Dr. Croone, do not appear to bear any direct relation to each other, 

 he divides the lecture into three distinct heads ; the first of which 

 contains an observation, and some experiments on the duration of 

 muscular action. In the second he traces the origin of sea-sickness, 

 from a mechanical cause deranging the circulation of the blood. In 

 the third he offers a mechanical explanation of the advantages de- 

 rived from riding, and the various modes of carriage exercise. 



With regard to the duration of muscular action, the author is of 

 opinion that each effort, apparently single, consists in reality of a 

 great number of contractions, repeated at extremely short intervals. 

 He infers the existence of these alternate motions, from a sound ob- 

 served upon inserting the extremity of the finger into the ear. The 

 sound resembles that of carriages at some distance passing rapidly 

 over a pavement. The sound is not perceived when the force applied 

 to stop the ear is not muscular, unless the action of some distant 

 muscle be communicated through some medium capable of conveying 

 its vibrations. 



With a view to estimate the frequency of these vibrations, the 

 author contrived to imitate them by rubbing a stick, regularly notched, 

 and placing it in such a position, that the tremor was communicated 

 to the ear along with the muscular vibrations. The results of such 



