WRITINGS OF JAMES SMITHSON. 75 



the cylinders through the substance of the cast-iron cylinder, 

 and issued over its internal surface in the state of fibres, 

 which were curled and twisted in various directions. This 

 form in the fibres of copper I had considered as very favour- 

 able to my hypothesis. Such was the tenuity of these fibres 

 of tin that little tufts of them applied to the flame of a 

 candle took fire, and burned like cotton. 



This passage of melted tin through cast-iron has a perfect 

 agreement with the passage of water by pressure through 

 gold, and tends to elucidate and confirm the account of the 

 celebrated Florentine experiment. Had the water on that 

 occasion issued solid, it would have been in fibres. 



This penetration of solid matters by fluids, by means of 

 great mechanical force, will, perhaps, come to be thought 

 deserving of more attention than has been yet paid to it ; 

 besides any scientific results to which the consideration of 

 it may lead, it may be found to afford compound substances, 

 not otherwise obtainable, and of value to the arts. 

 I am, sir, your most obedient servant, 



JAMES SMITHSON. 



ON THE DETECTION OF VERY MINUTE QUAN- 

 TITIES OF ARSENIC AND MERCURY. 



From Thomson's Annals of Philosophy, Vol. XX ; New Series, Vol. IV, 



1822, p. 127. 



SIR : To be able to discover exceedingly small quantities 

 of arsenic and mercury must, on many occasions, prove 

 conducive to the purposes of the chemist and the mineralo- 

 gist, more especially now that a very diminished scale of 

 experiment, highly to the advantage of these sciences, is 

 becoming daily more generally adopted. 



But the occasion above all others in which the power of 



