16 



MOLYBDENUM BLUE 



tained a few dark blue opaque particles of regular out- 

 line. They were almost cubic in shape. Fig. 3 shows 

 the slide under low power. The hydrosol was treated 



with NHjCl. Precipitate was separated from solution 

 by filtration. The blue filtrate was allowed to evapor- 

 ate over slides. Crystals were found as shown in Fig. 5 and 6. 

 As can be readily seen, they belong to the cubic system. It will 

 also be noticed that the corners are truncated. These little 

 faces do not appear on crystals on slide No. 2. These crystals 

 (No. 4) are pale blue in color. They are certainly not am- 

 monium chloride crystals. 



They are different from 

 cither molybdic oxide or 

 ammonium Molybdate. 

 It is therefore probable 

 that they are crystals 

 of crystalloidal Blue. 



Fig. 5 shows a cry- 

 stal under high power. 

 7'he truncated corners 

 can be seen quite dis- 

 tinctly. The cross in 

 centre appears quite 

 plainly. 



As will be noted 

 more fully later, the 

 hydrogel was found to 

 be soluble in absolute 

 alcohol. 



A concentrated solu- 

 tion of the Alcosol was 

 made. It was concen- 

 trated further by slow 

 evaporation. Fig. 3 

 shows a section of the 

 slide obtained. The 



Fig. S 



