314 



wire by which the power was conveyed from the negative end of the 

 battery. Lead, silver, copper, and iron, were successively employed ; 

 and it was by means of the last that the most distinct results were 

 obtained. 



When an iron wire, one seventieth of an inch in diameter, was made 

 the conductor on the negative side, and brought into contact with 

 moistened barytes or strontites, lime or magnesia, alumine or silex, 

 the globule formed by fusion at the end of the wire appeared in each 

 case to be alloyed with something capable of acting upon water ; but 

 those last named had, in succession, less action than the preceding. 



The author had not himself used mercury as a means of obtaining 

 the bases in a state of alloy till informed by a letter from Professor 

 Berzelius of Stockholm, who has used it with success for the decom- 

 position of lime and barytes. And Mr. Davy has found it to succeed 

 equally with strontites and magnesia. And although mercury alone 

 failed of effecting the decomposition of alumine and silex, yet when 

 an alloy of mercury and potassium was made the medium of commu- 

 nication even with these bodies, they each appeared to be decom- 

 posed by assistance of the affinity of potassium for their bases. 



The author also informs us of his success in repeating an experi- 

 ment of Professor Berzelius and Mr. Pontin, on the decomposition of 

 ammonia: a globule of mercury being inserted in a small cavity 

 made in a piece of carbonate or muriate of ammonia slightly moisten- 

 ed, they are placed together on a plate of platina positively electri- 

 fied, and the wire from the negative end of the battery is applied to 

 the mercury. The globule soon increases very considerably in bulk, 

 and becomes converted into a soft amalgam, which absorbs oxygen 

 from the atmosphere, or decomposes water into which it is thrown, 

 and forms ammonia, while the globule gradually recovers its fluidity, 

 and is reduced to its original size before the experiment. 



The Croonian Lecture. On the Functions of the Heart and Arteries. 

 By Thomas Young, M.D. For. Sec. R.S. Read November 10, 

 1808. [Phil. Trans. 1809, p. 1.] 



Since the degree and manner in which the circulation of the blood 

 depends upon the muscular and elastic powers of the heart and arte- 

 ries are questions belonging to the most refined departments of hy- 

 draulics, the author has already submitted to the Society those gene- 

 ral principles upon which he designs, in the present lecture, 1st, to 

 inquire what would be the nature of the circulation if the vessels 

 were as inelastic as glass or bone ; 2ndly, in what manner the pulse 

 would be transmitted if the tubes were merely elastic ; Srdly, what 

 actions may be ascribed to their muscular coats ; and, lastly, what 

 disturbances are occasioned in different kinds of fevers and inflam- 

 mations. 



In order to determine the velocity of the blood in different parts, 

 it is necessary to estimate the pressure by which it is urged forward, 

 and the resistance opposed to its motion. From the experiments of 



