384 M. Lamy on Thallium-glass. 



was melted under water in tubes of this dimension, and two 

 grammes introduced in small fragments which were previously 

 dried. That being done, the flask being held in a wet cloth, 

 the neck was rapidly drawn out and sealed ; this could be done 

 without the phosphorus taking fire provided the flask was held 

 vertically. The phosphorus was at first surrounded by whitish 

 vapours, and shone in darkness ; the interior then became clear, 

 and the phosphorescence disappeared. In twenty-four hours all 

 the oxygen was absorbed, and the phosphorus could then be 

 melted, which was done in a water-bath heated by means of a 

 small lamp. The flask was kept always in the same position, float- 

 ing on water, the neck uppermost, by its being placed in a hole 

 in the centre of a cork. Finally, to avoid the action of light, 

 the whole was surrounded by a cone of cardboard. 



After the lapse of a few hours, in the upper part of the flask, 

 and even into the neck, small brilliant points are observed, which 

 slowly increase and in two or three days are changed into a mag- 

 nificent crystalline arborization which covers all the surface, and 

 shines with all kinds of reflection and a lustre like that of the 

 diamond. The crystals evidently belong to the cubical system. 

 Many small crystals appeared to be regular cubes, and octahedra 

 could also be observed. Independently of crystals applied against 

 the sides, sometimes long salient needles having the aspect of 

 fern leaves were observed. 



In these experiments, if the phosphorus is suitably preserved 

 from light it is of a beautiful white ; but the moment it is struck, 

 not merely by the solar rays, but even by diffused light, it passes 

 in a few minutes into a garnet-red. In this new condition it 

 retains its crystalline form, transparence, and its lustre; the 

 crystals might be said to be small rubies. The crystalline form 

 is then so little altered that, if the apparatus is replaced in the 

 water-bath, new and perfectly white crystals are deposited on the 

 red crystals. Hence red phosphorus does not deserve the term 

 of amorphous which it generally receives — in this sense, that the 

 character does not essentially belong to it, but arises from the 

 difficulty, a posteriori, of crystallizing any body which, like it, is 

 infusible, insoluble, and absolutely fixed. 



Some of the thallic alcohols described by Lamy in 1864 are 

 liquids characterized by their great refractive and dispersive 

 powers ; ethyl-thallic alcohol in particular is the most refracting 

 of all known liquids. Lamy considered it probable that oxide 

 of thallium, substituted for potash or minium in the composition 

 of glass, would impart to it high refringent properties ; and he 

 accordingly undertook some experiments* on the subject, at first 



* Bulletin de la Societe 'Chimique, March 1866. 



