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crystals resembling the diamond, though generally of a reddish tint, 
and in this state it is the hardest of all sulsfances yet known, and 
scratches the diamond with ease ; 2, in metallic crystals, resembling 
graphite ; and 3, as a black amorphous powder. Boron combining with 
oxygen forms boric acid (a white crystalline powder much resembling 
silicic acid by its chemical properties), discovered in 1872 by Homberg, 
found in 1 776 by IIccfFer and Mascagni in the waters of tlie Lakes of 
Castel Nuovo, Monte-Cerboli, kc, in Tuscanj', and hitherto regarded as 
Bo 0^ ; that is, formeil with one atom of boron combined with three atoms 
of oxygen. But as boron is isomorphousf with tin, and as stannic 
acid, silicic acid, carbonic acid, and titanic acid contain only two atoms of 
oxygon, it is probable that boric acid will sooner or later turn out to be 
1)0 0'^ . 1^0 other oxide of boron has yet been dijcovered. 
Many chemists have endeavoured to ascertain the atomic weight of 
silicium, -which is generally thought to be 22. M. Marignac, the well- 
known and indefatigable chemist of Geneva, has just found that this 
number must be changed to 14 ; and that silicic acid is, consequentlj'', 
composed of one atom of silicium and two of oxygen (Si 0- ). When M. 
Dumas presented this result to the Academy of Science at Paris, a few 
days ago, it created, as may well be imagined, considerable sensation. 
The illustrious Berzelius himself had once remarked the probability of 
this formula, and Leopold Gmelin always looked upon quartz as composed 
of one of silicium aud two of oxygen. Mr. Miller in his " Mineralogy " 
advocates the same opinion, which was even suspected to be the exact 
one thirty years ago by Dumas ; and, finally, M. Gaudin, M. Marignac, 
and ourselves only waited for sufficient experimental proof to adopt it 
once for all. Indeed, we were on the point of again consulting our 
balance to investigate this question anew, when the results obtained by 
M. Marignac Avere laid before us.:]; 
M. Hermann von Meyer, the well-known pahcontologist, whosenamc 
has already appeared in one of our former papers, has announced to the 
Academy of Sciences of Paris, that he is about to send to that Society 
a work which he describes in these words : " My work treats of the 
Archegosaurus, the most marvellous animal that ever existed. The 
creature belongs to the family of the Labyrintliodonts, which became 
extinct before the end of the Triassic epoch. I have been fortunate 
enough to determine the entire organization of the Archegosaurus§ at 
each period of its life. It was in studying this animal that I first 
discovered the persistence of the embryonic condition of the vertebral 
Until nov/ the diamond has been considered the hai-dcst substance in nature. 
— T. L. P. 
t " Taking the same crystalline form." — T. I . P. 
X Marignac's Paper, which is extremely interesting, has been published in tho 
Comptes Rciidus of the Paris Academy of Sciences for the 3rd of May, 1858. Its 
purely chemical nature prevents our laying the details of it before our readers. — 
T. L. P. 
§ For some late observations on tlie Archogf saarus by Professor Owen, and an 
c.^:amination of some of M. von Meyer's views of its structure, sec Annals Nat. 
Hist., 3rd Scr., vol. T., p. 320.— Ed, Geol. 
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