

1824.] Mr. Phillips on Argillaceous Iron Ore. 449 



3*055, it yields easily to the knife, and becomes magnetic 

 when heated by the blowpipe. 



a. 100 grains of this ore reduced to powder and moderately 

 dried on a sand bath, lost one grain, which was evidently mere 

 hygrometric moisture. 



o. As it effervesces strongly when put into an acid, 100 

 grains were put into a vial containing sulphuric acid, the weight 

 of which and its contents were together noted. After the effer- 

 vescence was over, which took place slowly, it was found that 

 293 grains of carbonic acid were given out. The iron was evi- 

 dently in the state of protoxide, for crystals of protosulphate 

 of iron were obtained. Indeed no percarbonate of iron pro- 

 bably exists, or at any rate none has been described, and it 

 cannot be formed artificially. 



c. 200 grains of the ore were treated with muriatic acid ; nitric 

 acid was added to convert the protoxide of iron into peroxide. 

 The solution was decomposed by ammonia, and the peroxide of 

 iron precipitated, being washed, dried, and ignited, weighed 

 97*6 grains. On repeating the experiment the mean result was 

 96 # 15 = 48075 per cent. The iron in the ore exists as already 

 mentioned in the state of protoxide, and as 4U peroxide arc 

 equivalent to 36 protoxide, 48-075 are equal to 43-2G protoxide 

 of iron, which is the quantity contained in 100 grains of the ore. 

 (L The residuum insoluble in muriatic acid was of a dark 

 colour, and after being moderately dried, it was heated to red- 

 ness in a platina crucible ; by this it became perfectly white, 

 and lost 5*33 grains, which is the weight of the carbonaceous 

 matter. The insoluble residuum, consisting of silica and alu- 

 mina, gave a mean of 18-12 per cent. 



f. The ammoniacal solution, after the separation of the iron, 

 was treated with carbonate of ammonia; by this a quantity of 

 carbonate of lime was thrown down ; it weighed in one experi- 

 ment 7, and in the other 6*5 grains, giving a mean of 3-74 of 

 lime, which of course existed in the ore in the stale of carbonate. 

 J. The ammoniacal solution, evaporated so as to expel all 

 excess of ammonia, was treated with prussiate of potash ; a 

 precipitate of a light pinkish hue was obtained, but the quantity 

 was too small to allow of determining the quantity of oxide 

 of manganese which it indicated. 



It will then appear that the ore, usually, but improperly called 

 argillaceous iron ore, is in fact a carbonate of iron, consisting of 



a Moisture 10 



b Carbonic acid 29'3 



c Protoxide of iron 43*26 



. /Carbonaceous matter 5*33 



\ Silica and alumina 18' 12 



e Lime 3*74 



100-75 

 New Series, vol. Til. 2 o 



