JSO An Attempt to analyse Cast Iron.- 



(0-045-fO«017 = 0"062) from the whole of the extractive 

 substance (0-225 + 0- 170 = 0-395) consisted chiefly of silica 

 about 0"05. The remainder is oxide of iron, magnesia, 

 and a loss which is inevitable in such small experiments. 



2. The red-brown acid solution of iron was carefully 

 neutralized with caustic ammonia : a pale yellow precipi- 

 tate was slowly deposited, which I took to be a mixture of 

 silica and phosphate of iron. The precipitate on the filter 

 was well washed, dried, and ignited. On burning it 

 emitted vapours of sulphureous acid, and left at last 3*375 

 grammes of a beautiful red oxide of iron. It dissolved 

 completely in muriatic acid, and therefore did not contain 

 silica: nor did it show any signs of precipitation with a 

 solution of muriate of lead, even after several days. The 

 yellow mass which deposited on the neutralization of the 

 soluiion was therefore nothing but a sub-sulphate of oxide 

 of iron. 



3. The water employed to wash this precipitated sul- 

 phate of iron had deposited, after 48 hours, a salt in large 

 crystals, colourless, and resembling alum. They had a 

 sweetish astringent taste, and therefore from their external 

 character I supposed them to be alum. I dissolved them 

 in a caustic ley of potash. A great deal of ammonia was 

 disenoaged, and red oxide of iron was deposited in great 

 quantity, v^hich did not get darker by boiling, — a proof that 

 the salt did not contain any oxide of manaanese. The 

 ley of potash super-saturated with muriatic acid, and car- 

 bonate of amrnonia added in excess, aave no sign of tur- 

 bidness. This salt therefore contained no alumina, and 

 was a triple salt of sulphuric acid, anmionia, and oxide of 

 iron. 



4. The solution of iron which had been neutralized was 

 mixed with caustic ammonia in excess. The precipitate 

 taken on the filter was well edulcorated and mixed with 

 that before obtained (in No. 3), and thereafter ignited in a 

 platina crucible. The burnt oxide was dark-red, and 

 weighed 22*28 grammes. 



5. Three grtnimes of this oxide dissolved in muriatic 

 acid left on the filter a little of gelatinatcd silica, which 

 after burning weighed 0-01, answering to 22"28 oxide of 

 iron, equal O-Olb. 



6. The muriatic solution was neutralized as correctly as 

 possible with ammonia, then precipitated with benzoate of 

 potash, and filtered. The percolated solution was precipi- 

 tated with caustic potash in excess. The precipitate be- 

 came black in drying, and weighed after burning 0-2. 



When 



