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The walls of the test-tube or the object-glass, which exhibit the 

 said colour-phenomena, have that same structure, but with this diffe- 

 rence, that the globular, concentrically deposited spherolites have 

 much smaller dimensions and lie much closer together. Each little 

 spherolite has also a cross; this however, is not dark, bul coloured 

 with yellow and violet arms. The spherolite is also coloured in the 

 alternate circle-quadrants. 



This ensemble of small, coloured spherolites is the cause of the 

 said brilliant colour-phenomena; they are quite analogous to those 

 which are wont to appear in die case of liquid crystals and remain 

 in existence for an indefinite period. Each of them exhibits one or 

 generally two luminous points in the centre; they exhibit a strong 

 circular polarisation and are left-handed. The whole appears between 

 crossed nicols as a splendid variegated rnozaic of coloured cellular 

 parts. The size of each individual is 0.5— J micron. 



The acetate also exhibits something similar, but the spherolites are 

 built more radial and the whole is not at all so distinct. 



I hope to contribute more particulars as to these remarkable 

 phytosterol-compounds shortly. I have mentioned them here merely 

 to show the importance of this structure-form for the optical pheno- 

 mena, observed in the anisotropous phases. 



Zaandam, 14 November 1906. 



Chemistry. — "On irreversible phase-transitions in substances which 

 may exhibit more than one liquid condition." By Dr. F. M. 

 Jaeger. (Communicated by Prof. Franchimont). 



(Communicated in the meeting of November 24, 1906). 



§ 1. The fatty esters of a-Plu/tosterol from Calabar-fat, which the 

 Phytosterol mostly occurring in the vegetable kingdom, and which has 

 also been isolated from rye and wheat under the name of ''sitosterol'", 

 exhibit very remarkable properties in more than one respect. 



In my previous communication, I alluded briefly to the colour 

 phenomena and the spherolite-structure in the propionate and the 

 acetate. In the latter I could not observe anisotropous liquid phases ; 

 n the former a doubly-refracting phase is discernible just before 

 melting, but it lasts too short a time to allow the accurate measure- 

 ment of the temperature-traject. 



With the following four terms of the series, however, these pheno- 

 mena are more distinct, and occur under conditions so favourable as 



