Chemistry and Physics. 55 



fusibility, tenacity, and electrical conductivity also appear to 

 exert some influence as to the place of the different metals in 

 the list. 



It may be observed also that where it is desirable to avoid 

 discoloration of vacuum-tubes by the metallic deposit, this can 

 be effected by making the electrode within the tube of alum- 

 inum or magnesium, the interior portion of the platinum wire 

 which passes through the glass being itself covered with a 

 small glass tube. Of the two metals magnesium is the best, as 

 a wire hall a millimeter in diameter would not be at all affected 

 by discharges of the intensity ordinarily used with vacuum- 

 tubes, nor would it be so easily fused or rendered red hot as a 

 wire of platinum. Of course these metals could only be used 

 with gases which would have no chemical action upon them. 

 Yale College, December 13, 1876. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 

 1. On the so-called Crystallized Boron.— Haupe has prepared 

 and submitted to careful examination both .■( the forms of the 

 so-called crystallized boron, the black and the yellow, and finds 

 that neither is pure boron, both beintr coin pounds of this substance. 

 For the preparation of the black variety, 200 to 400 grams of 

 fused coarsely pulverized boric acid was placed in an English clay 

 crucible, a piece of aluminum weighing 100 to 200 grams was 

 laid upon it and cover* the cover of 



the crucible was luted on with clay. The whole was enclose! in 

 a Hessian crucible, the space between the two being filled with 

 quartz sand. The secret of the production of the black crystals 

 consists in the absence of carbon in the crucible. The fusion 

 was effected in a melting furnace, the fuel used being coke, and 

 the time of heating three hours. By closing the draft almost 

 completely, the cooling took place very slowly, requiring from 

 12 to 18 hours; the en - in -iz>' proportionally. 



On breaking the inner '. vor of the 



fused mass -ted of aluminum borate. Within 



this was a thin dense very hard la. . in. h un- 



rounded the resulus. The free - as well as 



the cavities in it were covered w;> u-k crystals, 



which were obtained on solution of the aluminum, accompanied 

 bv red hexagonal plates of the aln 



chocolate-brown crystals of silicon. The yield was small, only 

 2-5 to 3 cr tnriaum, one 



gram of which proved completely pure. Various other methods 

 of preparation were trii - l <*a in every case. 



The crystals are monoclinic prisms, have a brilliant metallic luster, 



