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XX. On the magnetic Attraction of Oxides oj Iron. By Timothy 
Lane, Esq. F. R. S. 
Read June 20, 1805. 
Having found by experiment, that hardened iron is not so 
readily attracted by the magnet as soft iron, and that needles 
are inferior to iron wire as indexes to Six's thermometer, I 
was proceeding to other comparative experiments, when I re- 
ceived the Second Part of last year’s Philosophical Transactions, 
in which I saw an Analysis of magnetical Pyrites, with Remarks 
on Sulphurets of Iron, by Mr. Hatchett. 
This Paper led me to examine what magnetical properties 
iron possessed, when free from inflammable matter. For this 
purpose I obtained a precipitate of iron, prepared and sold at 
Apothecaries’ Hall by the name of Ferrum prcecipitatnm. Mr. 
Moore, the chemical operator, informed me, that he pre- 
pared it by dissolving twelve pounds of sulphate of iron in 
twenty-four gallons of distilled water, and then adding eight 
ounces of sulphuric acid to render the solution more complete. 
Twelve pounds of purified kali were mixed with the solution : 
the precipitate was well washed with hot distilled water, and 
then carefully dried. This precipitate is similar to the sediment 
of chalybeate waters, and affords no magnetic particles ; nor, 
when exposed to a continued clear red heat, does it suffer any 
alteration beyond the acquirement of a darker colour. But if 
any smoke or flame has access to it, then magnetic particles 
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