186 Mil. E. SCflUNCK ON THE 



tinged with a dark purple colour, forming- a thin coating on 

 the exterior. The greater proportion of the plants, however, 

 bore leaves which did not exhibit the glaucous appearance 

 nor the fleshy consistency which, according to authors, are 

 characteristic of the cultivated variety of woad. They were, 

 on the contrary, of a bright grass-green and possessed but 

 little succulence, characters which belong rather to the wild 

 variety. 



As soon as I could collect a small ^juantity of leaves, I 

 commenced my experiments. Having taken some leaves, 1 

 chopped them fine and then extracted them with boiling 

 water. The filtered liquid was light brown and transparent, 

 it had a bitter taste and an acid reaction. It deposited no 

 indigo-blue, however long it might be left exposed to the 

 atmosphere, and hence it might have been inferred that it 

 contained no indigo-blue. Nevertheless, a very simple expe- 

 riment suflSced to show that it was capable of yielding an 

 appreciable quantity of that colouring matter. On adding 

 to it sulphuric or muriatic acid and boiling, it became of a 

 <larker colour and deposited a quantity of dark brown, almost 

 black flocks. Now these flocks contained indigo-blue, for if 

 after collecting them on a filter and washing out the acid, 

 they were treated with boiling alcohol, they communicated 

 to the latter a bright blue colour, and on being treated with 

 a boiling alkaline solution of protoxide of tin, they gave a 

 yellow solution, which on exposure to the air became covered 

 with a thin blue film. A small quantity of finely chopped 

 woad leaves having been pounded in a mortar with water 

 until converted into a uniform green pulp, yielded on being 

 strained through calico a dark green opaque liquor. On 

 heating this liquor to near the boiling point the vegetable 

 albumen contained in it coagulated, carrying down with it 

 the green colouring matter. On now filtering through paper 

 a green coagulum was left on the filter, while a clear light 

 yellow liquid ran through. On adding acetate of lead to the 



