310 Intelligence and Miscellaneous Articles* 



this would be couverted by the flame into protoxide, and thus act, 

 as before stated, on the oxide of copper ; and if, furthermore, this 

 latter substance were contained in too large a quantity in the borax 

 glass, it might become reduced by the sole action of the yellow 

 flame, and thus give rise to an erroneous result. To obviate, there- 

 fore, all doubt as to the presence or absence of FeO in any com- 

 pound, I find it advisable to conduct the operation in a different 

 manner, by which not the slightest uncertainty can be experienced. 



The borax bead must be coloured by a suflScient quantity of oxide 

 of copper to render it of a fine blue tint, but transparent, when cold. 

 To this the substance under examination in powder must be added, 

 and the bead exposed for a moment, or until the iron compound 

 begins to dissolve, to an oxidating flame. If peroxide of iron alone 

 be present, the glass will remain transparent, and of a green or 

 bluish-green colour ; but, on the contrary, if the added substance 

 contained protoxide of iron, the glass on cooling will be marked with 

 opake red patches, due to the reduction of the CuO to Cu'^ O, as 

 before explained. Care must be taken not to continue the blast too 

 long, otherwise the suboxide of copper might be again oxidized, and 

 the whole of the protoxide of iron converted into peroxide. After 

 one or two trials, however, no error can possibly arise. 



This reaction is not prevented by the presence of silica or other 

 acids. Amongst the silicates, the hedenhergite (a variety of au- 

 gite) 3CaO, 2Si03 ^ sFeO, 2SiO', the dark-coloured hornblendes 



^^ j Si03 + SFeO, 2SiOs, lievrite 3(3^^^8100 + 2(Fe« O^, SiO^), 



and other minerals, give very positive results. 



Finally, it will be perceived that in certain cases the protoxide of 

 iron, either alone or in combination as a salt, may serve to replace 

 tin in the detection of oxide of copper by the blowpipe. For in- 

 stance, when testing for minute portions of copper with borax on 

 the platinum wire, the glass must be removed to a piece of charcoal 

 if we wish to render evident the red suboxide by means of tin ; for 

 otherwise the end of the wire would be destroyed, the tin forming 

 with it a fusible alloy. By employing, however, a small fragment of 

 sulphate of iron to ensure this reduction, the bead may still be re- 

 tained on the platinum wire ; and we shall thus effect a saving of 

 time and trouble, and preserve our charcoal for other experiments, 

 an advantage of no little consequence when travelling, or in situa- 

 tions where good charcoal is not easily procurable. Nevertheless, 

 it must be confessed, that, under other circumstances, tin is, for this 

 purpose, the better reagent of the two. — From the Chemical Gazette 

 for March 1,1848. 



ON THE EXISTENCE OF SEVERAL METALS IN THE HUMAN 

 BLOOD, AND THE FIXED SALTS IT CONTAINS. 



M. Millon states, that when blood flowing from a vein is received 

 into about three times its bulk of water, and after this dilution is 



