DISOXIDATldN* OF IRON BY HIDROGEif GAS.' 377 



obtained by disoxidation contained 0*87 [13*44 grs,] of 

 earth; consequently there were 3*69 — 0*87 = 2*82 gr.' 

 [43-56 grs.] of pure iron.- In the analysis of this iron 

 4*07 gr. [62-86^rs.] of red oxide were obtained: the red 

 oxide therefore contained 4-07— 2*82= 1-25 gr. [19-31 grs.] 

 of oxigen; and consequently was at *|f|° per cent, or 44 

 per cent and upward, (allowing for any trifling errour). 



As to the iron of Elba, we find hy calculation, that the'and that of 

 red oxide obtained was at 43 per cent and upward, allowing 

 likewise for any trifling errour ; and if we take the mean 

 of the two results, admitting decimals and allowing for any 

 little errour, we shall findj^that the red oxide is at 44 per 

 cent. 



In some troublesome experiments, which I shall not de- Hidrogen ob- 



scribe, I was employed to obtain hidrogen by the decom- f^^^^^ ^'y P^^* 

 . . „ V. ^ ■ -r -, /. ^ng water over 



position of water, r or this purpose 1 took some very fine iron wire, 



iron wire, which I weighed and introduced into a gunbarrel, 

 adapted to this a retort filled with water, and proceeded in 

 the usual way. After the process I had a wire extremely state of tht 

 increased in size, consisting of an assemblage of octaedral *^°"* 

 crystals so small as to be visible only by a lens, and form- 

 ing a fragile wire oxided in all parts. I weighed it, and as 

 there were still some parts that had been less heated, and 

 not perfectly oxided, I pulverised the oxidule, subtracted 

 the iron thus separated, and on calculation found I had an 

 pxidule of 32 per cent and upward. 



DESROCHES. 



This is to certify, that these experiments were made at 

 the laboratory of the School of Mines in the month of 

 August, 1809, 



LE BOULLENGER. 



Observations by Mr, IIassenfratz. 

 It follows from the experiments of Mr. Desroches, that Observations bj 

 the oxidule of Cogne lost 0*317 of oxigen, which amounts ^^^^^j^ ^^^^' 

 to 46 parts to 100 of iron; and that the 'oligist iron of 

 Elba lost 0'3537; which would make more than 54 io 100 

 of iron. 



Th« 



