THE NEW YORK JOURNAL OF PHARMACY 



We note in general that the transfor- 

 mation of globules into crystals takes 

 place the sooner and the more quickly, 

 the lower the melting point of the 

 vehicle is. However, for purposes of 

 a rational comparison, one must con- 

 sider the purposes and properties of the 

 ointment bases: hydrocarbons, fats, 

 alcohol, cholesterin, vaseline. Taking 

 the diameter of the granules as 0.57 

 and the density of amorphous sulphur 

 as 1.92 there would be in i g of the 

 -2% sulphur ointment about 160,000,000 

 globules. Assuming the size limit of 

 colloid particles as 0. Iz^, sulphur glo- 

 bules would not figure as such on ac- 

 count of their large size. However, 

 they come very near to this limit and 

 in the lanolin ointment we find them 

 to be 0.2 and possibly still smaller — 

 consequently we can call this globular 

 form of sulphur the "disperse phase." 

 We have seen above that the globules 

 appear more or less rapidly, more or 

 less numerous, and that they are re- 

 placed by crystalline sulphur, that is, 

 by the solid phase. Inasmuch as the 

 crystals are formed at the expense of 



the globules and the latter are me- 

 chanically fixed in the solid ointment 

 body and, furthermore, inasmuch as 

 the crystals are formed with the as- 

 sistance of the molecules, we are com- 

 pelled to assume that the globules are 

 dissolved in the fat, forming a liquid 

 phase, from which the crystals with- 

 draw the amount of molecular sulphur 

 necessar}^ to their growth. In these 

 ointments we find the sulphur in three 

 different phases which are in a labile 

 equilibrium with one another. 



Disperse phase — liquid phase — solid 

 phase. 



The instability of the equilibrium 

 depends upon the solution tension of 

 the sulphur globules which is very 

 considerable on account of the relation- 

 ship of their volume to their tremen- 

 dously large surface, while the tension 

 of the sulphur crystal solution is very 

 slight on account of the minimal sur- 

 face of the crystals as compared with 

 their volume. 



A stable state of equilibrium : liquid 

 phase — solid phase is obtained only 

 when the disperse phase of sulphur in 



