Chemistry and Physics. 153 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. Artificial Diamonds from Fused Silicates. — Since it seemed 

 probable that natural diamonds have been formed by crystalliza- 

 tion from silicate magmas, it occurred to R. v. Hasslinger, that 

 they might be prepared artificially in this way. A mixture cor- 

 responding to the analysis of a diamond-bearing breccia (SiO„, 

 40-30; Al 2 O s , 9-45; K 2 0, -90; Na 2 0, 4'93 ; Fe a b 3 , 7'30 ; MgO, 

 21*10; CaO, 3.48 ; loss by ignition, 13-00) was found to be too 

 infusible when the usual methods of beating were used, hence the 

 method of Goldschmidt, the so-called "thermite" process, was 

 employed. Instead of magnesium and aluminum oxides in the 

 mixture which has been given the corresponding amounts of the 

 metals were used, and an amount of ferric oxide sufficient to 

 oxidize them was added. To this mixture carbon was added at 

 the rate of one or two per cent, best in the form of very fine 

 graphite. Portions amounting to about 300 g of this mixture 

 were placed in Hessian crucibles, surrounded by ashes and sand, 

 and ignited, with the result that satisfactory fusions were pro- 

 duced by the reaction and diamonds were formed in the fused 

 mass. It was found impossible to detect the diamonds in thin 

 sections of the slag, because, on account of their hardness, they 

 were broken out in grinding. The mass was accordingly dis- 

 solved in a mixture of ammonium fluoride and sulphuric acid, 

 and the insoluble residue was examined. Absolutely colorless 

 and transparent octahedrons were found, having an average 

 diameter of -05 mm . They scratched ruby and were combustible 

 when heated with oxygen. The results appear to strengthen the 

 theory that natural diamonds have been formed by crystallization 

 from silicates. It should be stated that the metallic iron pro- 

 duced in the experiments was found to contain carbon only in 

 the graphitic and amorphous forms. — Monaishefte, xxiii, 817. 



H. L. W. 



2. Fluorescence and Phosphorescence of Diamonds. — Marck 

 wald has observed that the rays emitted by polonium (now called 

 radio-active tellurium ; see the following notice) induce fluores- 

 cence in diamonds. Rosenheim has examined this behavior with 

 diamonds from various localities, and finds that all of them show 

 this property. In this way diamonds could be distinguished from 

 other precious stones, such as ruby, emerald, zircon, topaz, opal, 

 etc. For these experiments the bismuth rod coated with a radio- 

 active substance, recently described by Marckwald, was placed 

 close to the objects, and observation was made in total darkness. 

 The rays emitted by diamonds, under the influence of the rod, act 

 upon the photographic plate, even after an exposure of only two 

 minutes. The rays from the rod also act upon the plate, but 

 these are readily cut off by the interposition of substances such 



Am. Jour. Sci. — Fouhth Series, Vol. XV. No. 86.— February, ]903. 

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