456 Intelligence and Miscellaneous Articles, 



is very dark green, and minute spangles of the sesquioxide of chrome 

 are easily recognized in it. 



Third Experiment. — With 40 grms. of the hichromate, the fusion 

 is decidedly more difficult, and the glass is filled with extremely 

 brilliant crystals. Those persons who saw specimens of this glass, 

 at once compared it to Venetian aventurine, and called it chrome 

 aventurine, which name I propose to retain. 



FourthExperiment. — With 50 grms. of the bichromate, fusion is ex- 

 tremely difficult. The glass is filled with a confused mass of span- 

 gles, and has no longer the lustre and beauty of the preceding. 



Hence the best proportions for the preparation of the chrome 

 aventurine are these : — 



Sand 250 parts, 



Carbonate of soda 100 ,, 



Carbonate of lime 50 ,, 



Bichromate of potash . . 40 ,, 



The resulting glass contains from 6 to 7 per cent, of oxide of 

 chrome, nearly half of which is combined with the glass, the other 

 half remaining free in the form of brilliant scales or spangles. 



The green aventurine is much more easity prepared than the 

 Venetian. It exists during the fusion of the glass, while the latter 

 is only formed during the annealing. I may refer those who are 

 interested in this question to Fremy and Clemandot's paper upon 

 artificial aventurine in the Comptes Rendus for 1846, p. 341*. 



Chrome aventurine sparkles in the sun and in strongly lighted 

 places ; in this respect it is surpassed by the diamond alone. It is 

 harder than common glass, which it scratches and cuts easily, and 

 is especially harder than the Venetian aventurine ; hence its greater 

 value. 



Among the irregularities presented by the outlines of the spangles 

 disseminated in the chrome aventurine, M. Daubree has recognized 

 with certainty the form of the regular hexagon, which belongs to 

 the crystalline system of the sesquioxide of chrome. Moreover the 

 spangles have the greatest resemblance to certain varieties of lami- 

 nated oligistic iron ore, such as are met with in certain lodes, espe- 

 cially the specular variety ; and it is well known that oligiste iron 

 is isomorphous with the sesquioxide of chrome. 



The colour of the new aventurine is that of the third yellowish 

 green, the thirteenth shade in M. Chevreul's chromatic circle. 



The lapidaries who saw my first specimens of the new aventurine, 

 and who cut some of them, agree in stating that it forms an important 

 acquisition to their branch of manufacture, for which reason I have 

 thought it worth making public. — Comptes Rendus, October 16, 1865. 



ON THE DETECTION OF POISONING BY CARBONIC OXIDE. 

 BY M. HOPPE-SEYLER. 



Blood charged with carbonic oxide, investigated in the solar spec- 

 trum after suitable dilution, exhibits almost exactly the same absorp- 

 tion-bands as oxygenated blood. If sulphide of ammonium be added, 

 the bands do not disappear for some days ; while blood free from 

 * See also Chem. Gazette for April 1846, p. 141. 



