476 Scientific Intelligence. 



dodecahedrons. Retgers however has experimented with essen- 

 tial oils used as solvents and has not been able to confirm the 

 production of dodecahedrons under these circumstances. Indeed 

 it would appear that under certain conditions the yellow variety 

 of phosphorus is amorphous; as when it is obtained in a thin 

 layer between two slips of glass. With reference to the action 

 of heat on this substance, the author observes that when heated 

 phosphorus passes through three stages of change. In the first 

 it becomes yellow to brown, though still remaining regular and 

 transparent. In the second a granular, undoubtedly crystalline 

 segregation occurs, red opake phosphorus being formed. And in 

 the third there is produced a graphitic chocolate-colored phos- 

 phorus. The first production of a true modification occurs at the 

 second stage. Light was observed to produce a similar series of 

 changes, these changes not being confined to the surface. The 

 character of the white crust which forms on phosphorus when 

 submerged in water, the author has not finally determined though 

 he considers it a hydrate rather than a different modification. 

 Since the properties of an amorphous modification so far as 

 known, are never intermediate between those of two crystalline 

 modifications, this rule would be violated if red phosphorus were 

 amorphous; for the density of red phosphorus is 2'148 and that 

 of yellow phosphorus is 1-826; while that of the chocolate-col- 

 ored hexagonal variety is 2-34. — Zeit. Anorg. 6 hem., v, 211, 

 October 1893. a. f. b. 



4. On the Behavior of Carbon, Boron and Silicon in the 

 Electric Furnace. — In continuing his experiments with the elec- 

 tric furnace Moissan has now subjected carbon, boron and sili- 

 con to the action of the electric arc. At a somewhat high 

 temperature, the diamond under those circumstances becomes 

 incandescent and swells up without melting, covering itself with 

 black particles entirely consisting of hexagonal plates of graphite 

 easily convertible into graphitic oxide. When placed in a small 

 carbon crucible and acted on by an arc produced by 70 volts and 

 400 amperes, the diamond first breaks up into fragments along 

 the planes of cleavage and then swells up as the temperature rises 

 and is completely converted into graphite. Hence it appears 

 that the stable form of carbon is graphite, even at the tempera- 

 ture of only a moderately intense electric arc. If heated in a 

 carbon enclosing vessel, in a jet of oxygen and hydrogen gases, 

 however, the diamond is sometimes covered with a black adher- 

 ing mass which slowly dissolves in a- mixture of nitric acid and 

 potassium chlorate but which is not graphite. Amorphous boron 

 volatilizes without fusion in the electric arc, the ends of the elec- 

 trodes being converted into semi-crystallized boron carbide. 

 Silicon thus treated melts and then boils, covering the ends of 

 the carbon electrodes with pale green crystals of carbon silicide. 



This carbon silicide Moissan has studied more carefully. He 

 finds that when carbon is dissolved in fused silicon in a wind 

 furnace, crystals of carbon silicide several millimeters in length 



