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ON THE NATURE OP POTASSIUM AND SODIUM. JJ 



" The line of contact of the tube, when the weights were Change of p». 

 first suspended, traversed the poles of the centre bar of the duc^d no*"l- 

 niagnet only; but while they remained attached, I turned terationinthe 

 the tube till it stood in a diagonal direction with the extreme *ff«ct. 

 angles of the outside bars; but no difference of attraction 

 was indicated, as it would not sustain more, or separate 

 with less weight, than in its first position; 



I then increased the width of the line of contact in the On increasinf 

 tube, with a file, to about ,V of an inch, and found that it »he contact by 

 separated with nearly a pound less weight: I increased its facef the at- ' 

 width still more, and the attraction was proportionably less, traction dimf- * 



This led me to suppose, that the extraordmary degree of 

 attractive force, by which the tube was held to the magnet Under^ adhered 

 in the first instance, depended entirely on the minuteness '"°'6^'^«^ly 

 of the line of contact; and of course, that a solid piece ^* * ^* 

 of sound iron of the same diameter, would be similarly 

 attracted. To prove this however, I procured a solid cylin- ' 

 der of iron the same length and diametier as the tube; but 

 upon applying the weights, 1 was surprised to find it sepa^ 

 rate with less than half what was necessary to displace the 

 conductor belonging to the magnet. 



These hitherto unexplained, and probably unobserved, 

 phenomena, are submitted for explanation to such of your 

 philosophic readers, as may have paid more attention to 

 this subject, than I have had an opportunity of doing; 

 in hopes of being gratified with some communications, 

 which will not fail to be interesting, while they elicit a more 

 extensive inquiry into that mysterious and neglected princi- "'^ 



pie of nature, magnetism. 



Yours, &c. 

 London, April the 10/A, 1811. E. LYDIATT. 



V. 



•An Answer to Mr, Murray's Observations on the Nature of 

 Potassium and Sodium: by Mr, John Davy, 



To Mr. NICHOLSON. 

 SIR, 



; 



♦»&*! 



R. Berthollet has estimated the proportion of water in Quantity of 

 common fused potash at 13*9 per cent ; and Mr. Davy, from water in pot- 



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