Henry Basseft, Jnn. — Prepat-atlon of SpJteniUtes. 



15 



As piire sulphanilic acid is colourless the bluish-grey colour must 

 be due to the production in the course of the reaction of a small 

 quantity of impurity, which is of the nature of an aniline dye. 



When we come to study the spherulites more closely we find that, 

 not only do they exhibit an alternation of colour in concentric shells, 

 ])ut also that near the upper surface of the mass, as incomplete 

 «pherulites developed downwards these were prolonged as a kind 

 of film on the surface of the glass above the solid mass, this film 

 no doubt being originally caused by the adherence to the glass of 

 a small quantity of liquid when the vessel was shaken. An 

 examination of this thin section (as it were) of a spherulite shows 

 that the pale bands in the solid mass are continued on the surface 

 of the glass as bands of closely packed crystals, while the dark 

 bands coincide with the bands on the glass where there are very 



Photograph of the bottom nf a flask containing tlie spherulitic structure. 



few crystals. It is thus quite obvious that the alternate dark and 

 light rings of the spherulites have been caused by a zoning out 

 of the sulphanilic acid, the interstices having been filled up by the 

 blue, very viscous magma (for only about 40 per cent, of the mass 

 is sulphanilic acid, the rest being chiefly sulphuric acid). On this 

 supposition the rings would be formed as follows : — A ring of 

 radiating crystals would first be formed round some nucleus, but as 

 the surrounding magma would thus be deprived of most of the 

 sulphanilic acid it contained in solution, this ring would be succeeded 

 by a ring where there were very few crystals, then another ring 

 with a great many crystals would follow, and so on. The formation 

 of these spherulites would thus be very analogous to the formation 

 of ' Napoleonite ' and spheroidal granites, to take extreme cases^ 



