368 Mr. H. M, Vernon on a New 



into the other, but it must be repeated another time in the 

 slow cooling, and two or three times more in the rapid cooling. 

 It is very easy to obtain an idea as to the proportions of each 

 variety present in any specimen by taking its rate of rise of 

 temperature, the form of the curve obtained being between 

 those of the two given, and the melting-point also varying 

 between the extremes 44°*3 and 45°'3. It is therefore 

 possible by alternate rapid and slow cooling to convert phos- 

 phorus backwards and forwards from one variety to the other 

 as often as is desired. 



As a single rapid or slow cooling is not sufficient to wholly 

 convert one variety into the other, it follows that the phos- 

 phorus, when melted, must also be in a different state in the 

 two cases, thus differing from sulphur, with which, though 

 there are several different crystalline states, there is only one 

 liquid state. 



Up to the present phosphorus has always been stated to 

 crystallize in octahedral or rhombic dodecahedral crystals. It 

 is necessary therefore to ascertain which of the above varieties 

 crystallizes in this form, and in what form the other variety 

 crystallizes. It was at first endeavoured to crystallize out the 

 phosphorus from its solution in carbon disulphide. About 

 equal volumes of carbon disulphide and phosphorus were 

 mixed and the excess of carbon disulphide distilled off ; but 

 the solution, though left for some time, did not crystallize. 

 It would probably be only possible to obtain good crystals by 

 operating on very large quantities of material, as carbon 

 disulphide dissolves about eighteen times its weight of phos- 

 phorus, and so the whole of the phosphorus would crystallize 

 out by the evaporation of this very small quantity of carbon 

 disulphide. Benzene only dissolves phosphorus to a slight 

 extent, but it was found possible to obtain small crystals by 

 first warming the benzene with the phosphorus to 40° and 

 then allowing the solution to slowly cool down. All the ope- 

 rations were performed in sealed glass tubes with a bend in the 

 middle, and after the crystals had been deposited in one limb 

 the benzene was poured off' into the other, the crystals being 

 thus left free for examination. The tubes containing the 

 crystals were then examined under a microscope with a power 

 of ten diameters. The crystals from the modification with 

 the undefined melting-point were observed distinctly to crys- 

 tallize in rhombic prisms ; but as, from their inflammable 

 nature, it was not possible to examine them except in the 

 glass tube, no measurements could be taken. Some of the 

 crystals were in masses, with smaller crystals shooting out in 

 different directions at right angles from the larger ones : none 

 of the crystals were, however, more than about 5 millim. in 



