624 THE POPULAR SCIENCE MONTHLY. 



translucent, they scratched a ruby, and they distinctly showed 

 under the microscope the crystalline structure and cleavage of 

 the diamond ; their density was that of the precious gem, and 

 they were completely consumed in oxygen at a temperature of 

 1,890°.* 



Mr. Marsden's experiment with silver was also repeated ; but 

 silver being a bad dissolvent for carbon, even at a high tempera- 

 ture, it was boiled for some time with sugar charcoal in the fur- 

 nace, the cooling being operated in the same way as with iron. 

 The result was extremely interesting. No diamonds were ob- 

 tained, but a series of carbonados of different densities (from 2"5 

 to 3'5 times heavier than water) were discovered, some of them 

 in grains, some others in needles, or in conchoidal masses, the 

 densest ones also scratching ruby and burning in oxygen at 

 1,800°. This is perhaps the most interesting part of Moissan's re- 

 searches, as it confirms the long-since suspected fact that there is 

 a whole series of carbon molecules each of which is composed of 

 a different number of atoms, and some of which must be very 

 complex. 



As to the quantities of diamond dust obtained in this way, 

 they were extremely small. Several cylinders gave no diamonds 

 at all, and from all his experiments Moissan could not collect 

 even a few milligrammes (a few hundredth parts of a grain) of 

 the precious dust, although the black carbonados were quite com- 

 mon. But a sure method is now indicated, and its further devel- 

 opment is only a matter of time and perseverance. 



The scientific value of these researches is undoubtedly very 

 great. Diamond, like graphite and simple charcoal, is pure car- 

 bon, but all attempts at fusing carbon or dissolving it have hith- 

 erto failed ; it could not be brought into a liquid condition out of 

 which it afterward might crystallize. However, the investiga- 

 tions recently made into the carburization of iron, especially by 

 Roberts Austen, tended to prove that in steel and cast iron the 

 carbon is not simply diffused through the iron, but enters with it 

 into some of those combinations in definite proportions which, 

 like all solutions, occupy an intermediate position between real 

 chemical compounds and purely physical mixtures, f It was 

 reasonable, therefore, to presume that carbon is brought into a 

 liquid condition in molten iron, and that under certain conditions 

 it may crystallize in the shape of diamonds within an iron mass. 

 Moissan's discovery confirms this view. On the other side, the 

 researches of Moissan and Friedel must also throw some light 



* From a subsequent communication by Moissan we learn that the same varieties are 

 found in the diamond-bearing earth at the Cape. 



f See Recent Science, in Popular Science Monthly, October, 1892. 



