IRON RUST. 303 



particles of the metal in the rust. I could not, of course, 

 make quite certain without other appliances, so on my return 

 to Sydney 1 examined the rust carefully for metalhc iron by 

 grinding it in an agate mortar, but could not find the 

 smallest speck of metal ; the material ground readily to the 

 last portion and yielded a dark brown coloured powder, and, 

 to my surprise, I found the powder to j)e wholly attracted by 

 tlie magnet, and not merely in part as I expected. I did not 

 care to publish the above as it rested upon observations 

 made upon a single specimen, and was directly opposed to 

 the usual statements in text-books and works of reference 

 on chemistry, that rust is a non-magnetic hydrated sesqui- 

 oxide of iron, and an opportunity to proceed with the matter 

 did not occur until September last. 



It may be thought that more has been made of the matter 

 than its comparative unimportance warrants, but as my 

 results are at variance with the general statements placed 

 before students and others, statements which are of so many 

 years standing, it is perhaps not unjustifiable to place suffi- 

 cient evidence on record to establish the facts and place them 

 on a firm footing. Fortnnately the statements can be verified 

 l)y anyone possessing a magnet, no matter how poor a one it 

 may be, inasmuch as material can be obtained from any old 

 piece of rusty iron. 



Since then I have been able to examine other specimens 

 of rust and to make a iew experiments upon the matter, 

 all of which bear out the original observation, and show that 

 ordinary iron rust is usually attracted by the magnet. 



By magnetic rust or oxide in this paper is meant iron 

 oxides which are attracted and lifted by a small bar magnet 

 of one-eighth inch in diameter, or by an ordinary penknife 

 blade which had been magnetised ; but when seeking to 

 separate large quantities a bar magnet which would lift 4 ozs. 

 of iron or an electro-magnet lifting 18 ozs, was employed. 

 As mentioned in the preceding paper, a powerful electro- 

 magnet was considered inadmissible. 



In spite of all the care exercised in grinding and using the 

 magnet under water, there may still be some non-magnetic 

 oxide mechanically enclosed and carried over by the magnetic 

 particles, as is seen when it is attempted to separate sulphur 

 and iron filings by a magnet ; but from the number of times 

 that the same powder can be lifted without leaving anything 

 behind I think it cannot amount to much, and may be 

 neglected as unimportant. 



