390 Journal of the Asiatic Society of Bengal. [August, 1910. 



1 ' Thousand-puta lauha." M Thousand-puta lauha.' ' 



Fe 



(A). 



• • 



(B) 

 nil. Fe = nil. 



FeO .. = nil. FeO .. = nil. 



Fe 9 0, .. = 78-1 Fe 0, .. = 846 



2^3 



2 W 3 



Siliceous matter. . = 17*9 Siliceous matter. . » 11-3 



Soluble salt . . = 4-1 Soluble salt of which 



PoO, = 12. = 8-8 



1001 



99-7 



Discussion of Results. 



From the above it is clear that the magnetic properties of 

 the samples of iron which have undergone fewer number of 

 " putas" are not due to free iron, which is present in minute 

 quantities in the "one-puta" €i lauha," but to ferroso- ferric 

 oxides, the ferrous and ferric oxides being present in them in 

 varying proportions. 1 As the number of "putas" increases, 

 the amount of ferrous oxide diminishes, and at the hundred 

 ' ' putas ' ' and above , the iron is wholly present in the form of 

 ferric oxide. Hence " hundred-puta " and " thousand puta f9 

 " lauhas " are not attracted by the magnet. 



2. Siliceous matter is present in very large proportions 

 varying from 10*1 to as much as 34*1 per cent. This impurity 

 most probably comes from the unglazed earthenware pots that 

 are used for roasting. 



3. " Shata-puta " and " shahasra-puta " " lauhas M have 

 almost identical compositions. Both are impure ferric oxide, 

 the percentage of which varies from 78-1 to 84*6. Both are 

 non-magnetic and u swim like a duck " on water. On account 

 of the very large number of * ' putas , ' ' in the course of which 

 it undergoes maceration, powdering and roasting for a thousand 

 times, the " shahasra-puta ' ' " lauha " is lighter and finer than 

 "shata-puta." The time taken to prepare these lauhas is 

 very long indeed. If one " puta " be finished in one day, the 

 preparation of ' ' shata-puta ' ' takes more than three months 

 and that of "shahasra-puta" about three years. As the 

 roasting is carried on in closed vessels the oxidation proceeds 



i 



l Cf. Roscoe and Schorlemmer's Treatise on Chemistry, Vol. II, 

 Part 2, " Magnetic oxide of iron " :— " When iron is heated to redness 

 in the air, it becomes coated with an iron scale. This is a mixture or a 

 compound of the monoxide and sesquioxide in varying proportions 

 The inner layer which is blackened grey, porous, brittle and attracted 



by the m~ ~ " ^ Al '" ™ ~ • ' ' ~~ +; " 



The outer layer contains a large quantity 



agnet, has the composition 6Fe6 Fe 2 03 anc ^ i s not magneti 

 : laver contains a larsre auant.it.tr nf fnmo. rvride. is of areddis 



inner 



portion. 



* » 



