Cambridge Philosophica I Society. 315 



and red in transmitted light, and unalterable in the air. The 



lead becomes much less fusible, and that which has been already 



used is more suited for the formation of crystals on its surface. 



The lead contains crystals dissolved which are not detected on 



cutting it, but may be obtained on dissolving the lead by the 



prolonged action of cold nitric acid of 1*1 spec. grav. The 



crystals thus obtained appear to be rhombohedra, and are thus 



probably isomorphous with the crystals of As, Sb, and Bi. There 



is then a metallic phosphorus which is amorphous in Schrotter's 



modification and crystallized in this new form, and a non-metallic 



form — that originally discovered by Brandt. The new metallic 



phosphorus has the spec. grav. 2*34 at 15°-5 C. • and its atomic 



31 

 volume, 7 r- F - r = 13*25, is identical with that of metallic arsenic. 

 ' 2*34 ' 



Amorphous phosphorus, when heated for a long time, passes 



into the crystalline modification. 



Crystallized phosphorus is less volatile even than amorphous. 

 It forms no colourless phosphorus below 358°. The maximum 

 tension and vapour-density are at all temperatures far lower 

 than those of amorphous phosphorus. Thus at 447° a litre of 

 the vapour weighs 2*573 grms. and has the tension 928 millims. 

 At 530° the weight is 10*198 to 10*338 grms., and the tension 

 4101 to 4158 millims. The author points out that phosphorus 

 is probably the first body which has a different tension in its 

 different modifications. He shows, too, that the vapour of 

 colourless phosphorus retains its density and tension unaltered 

 even if in contact with the amorphous metallic phosphorus. 



Hittorf states that Geissler, by placing colourless phosphorus- 

 vapour in closed glass tubes, has changed it into red by passing 

 the electric spark through it while in the state of vapour. The 

 author shows that sunlight does not change the vapour, nor does 

 the electric light. Yet a white heat effects the change to a 

 small extent, as is seen when phosphorus-vapour is driven through 

 a white-hot porcelain tube by means of a current of hydrogen. 

 The same effect is produced if charcoal-points placed in the 

 vapour are raised to incandescence by the electric current. 



XL VI I. Proceedings of Learned Societies. 



CAMBRIDGE PHILOSOPHICAL SOCIETY. 

 [Continued from p. 233.] 

 Feb. 26, " f~^)N the Papyrus of the Lake of Gennesaret." By 



1866. ^J Professor Cardale Babington. 



The author pointed out the distinctions between Cyperus papyrus 

 and Cyperus syriacus. The former, the papyrus of history, grows 

 in Nubia and on the White Nile, and was found (by Rev. H. B. 



