454 Contributions to the Chemistry of Chlorophyll. 



well crystallised and appeared to be pure, but I will not give the 

 results until I have had an opportunity of confirming them with 

 freshly prepared material. The difficulty experienced in preparing 

 sufficient quantities of pure substances from chlorophyll has proved 

 a great drawback in this investigation and has much retarded its 

 progress. 



My friend Dr. Burghardt, of the Owens College, has had the 

 kindness to examine at my request the crystalline form (fig. 2) of 

 phyllotaonin, and reports as follows : — 



Fig. 2. 



Crystal system monosymmetrical, oblique rectangular prism, formed 

 by the combination of the ortho- and clino-pinacoids. 



The terminal faces are a negative hemipyramid. The faces b 

 (010 Miller or aMa, Naumann) predominate, giving a " vertical 

 tabular habit " to the crystal. 



It was impossible to obtain any measurements of the angles owing 

 to the smallness of the crystals and the roughness of the faces. The 

 value, therefore, of the hemipyramid indices is unknown. The faces 

 "a" are 100 (Miller) or a£ra. (Naumann), whilst the faces "c" are 

 the negative hemipyramid —Ml (Miller) or —mP (JNaumann). 



They cleave parallel to the ortho- pinacoid distinctly. Examined in 

 polarised light they exhibit depolarisation, on rotating the Nicol's 

 prism the colour changing from a light-yellow to a rich brownish- 

 red. 



