259 



The examination of the incrustation upon ancient coins showed it 

 to consist of oxide of tin, and of carbonate and submuriate of tin,' and 

 of carbonate and submuriate of copper. It in some cases acquires a 

 dingy hue from the prevalence of black oxide of copper, mixed with 

 a little of its protoxide. 



The author could discover no connexion between the perfect state 

 of preservation of ancient coins, and their composition ; but he ob- 

 serves that the manner in which the crystalline structure of the in- 

 crustation is acquired is a peculiarly interesting question. There 

 being no reason to suspect deposition from solution, " are we not," 

 says the author, " under the necessity of inferring, that the mineral- 

 izing process witnessed in its effects, depends on a slow motion and 

 separation of the particles of the original compound ? And must we 

 not conclude that this motion is connected with the operation of 

 attractions of different kinds, as chemical affinity, electro-chemical 

 attraction, and attraction of aggregation?" If this conclusion be 

 just, the author remarks that it opens a new field of inquiry, which 

 may help to explain several phenomena in mineralogy and geology. 



Additional Proof s of Animal Heat being influenced by the Nerves. By 

 Sir Everard Home, Bart. V.P.R.S. Read November 16, 1825. 

 [Phil. Trans. 1826, Part II. p. 60.] 



In this communication Sir Everard gives an account of a repetition 

 of his former experiments upon the effect of dividing the nerves that 

 supply the velvet of the deer's horns, and in which some sources of 

 error have been avoided. The general results are the same as those 

 formerly obtained ; the temperature of the horn, the nerves of which 

 were divided, was diminished to the amount of 7; and, as before, 

 the disparity of temperature gradually decreased until, after the 

 lapse of about twelve days, the temperatures of the two horns were 

 the same. Upon examining the structure of the parts after the ani- 

 mal's death, it was found that the interval between the divided ends 

 of the nerves was filled up by a newly-formed connecting substance, 

 capable of restoring their action. 



In further illustration of the effect of the nerves in producing heat, 

 independent of mere circulation of blood, the author mentions a case 

 of aneurism, in which the femoral artery was tied without occasion- 

 ing any diminution in the temperature of the foot. 



The Croonian Lecture. On the Structure of a muscular Fibre from 

 which is derived its Elongation and Contraction. By Sir Everard 

 Home, Bart. V.P.R.S. Read December 15, 1825. [Phil. Trans. 

 1826, Part II. p. 64.] 



In this paper, after attending to the striking analogy between the 

 structure of a nervous and of a muscular fibre, as demonstrated by 

 Mr. Bauer's microscopical observations, Sir Everard adverts to an 

 error into which he had fallen, in his former examination of the 



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