ITS PROPERTIES AND COMPOSITION MUNRO 



13 



A test tube containing a brown solution ob- 

 tained by reduction by zinc and H2SO4 was treated 

 with three drops of H, O^. A green color appeared 

 in two thirds of the tube. Another drop of per- 

 oxide was then added. This gave a blue solution 

 in the upper part of the tube. These experiments 



■ show conclusively that the green and browns are 



successive reduction products. 

 The colloidal nature of the blue was confirmed 

 by adding an electrolyte (NaCl) to the clear filtrate. 

 '°' The mixture was shaken. A precipitate formed. 



After allowing the solution to stand for a few hours, the pre- 

 cipitate was removed by filtration. The filtrate was still blue. 

 More electrolyte was added but no further precipitate was 

 obtained. The fact that the filtrate was blue would suggest 

 that Molybdenum Blue exists in the crystalloidal form also. 



A simple dialyzer was made by covering the mouth of a 

 funnel tube 2" in diameter, with a membrane of sheepskin. 

 Solutions of the Blue, the filtrates from the preparation by 

 SnClz and H2S, were placed in the dialyzer and the latter kept 

 immersed in distilled water for five days. The water was chang- 

 ed every twelve hours. After twelve hours dialysis, some of the 

 water was evaporated over microscopic slides. Examination 

 under the microscope revealed large amount of stannous chloride 

 crystals. Slides prepared after thirty hours dialysis showed 

 stannous chloride needles, and a little Blue. At the end of 

 four days continuous dialysis, the water in which the dialyzei* 

 had been immersed for twelve hours, gave almost no deposit 

 on the slide. This slight deposit consisted of tint patches of 

 Blue with a mere trace of stannous chloride. That some Blue 

 passes through the membrance would suggest that it might be 

 crystalloidal as v/ell as colloidal. The blue patches might well 

 be aggregations of ultramicroscopic crystals. 



The bleaching action of animal charcoal on solution of 

 Molybdenum Blue was tried. The blue solution was soon 

 bleached by the charcoal. Concerning this phonomenon Zsig- 



