VOYAGE TO ALGERIA. 221 



called ultra-marine ; but looked fairly down upon, it 

 was of almost inky blackness black qualified by a 

 trace of indigo. 



What change does the home examination here 

 reveal ? In passing to indigo, the water becomes sud- 

 denly augmented in purity, the suspended matter 

 becoming suddenly less. Off Tarifa, the deep indigo 

 disappears, and the sea is undecided in colour. Accom- 

 panying this change, we have a rise in the quantity of 

 suspended matter. Beyond Tarifa, we change to cobalt- 

 blue, the suspended matter falling at the same time in 

 quantity. This water is distinctly purer than the 

 green. We approach Cadiz, and at twelve miles from 

 the city get into yellow-green water ; this the London 

 examination shows to be thick with suspended matter. 

 The same is true of Cadiz harbour, and also of a point 

 fourteen miles from Cadiz in the homeward direction. 

 Here there is a sudden change from yellow-green to a 

 bright emerald-green, and accompanying the change 

 a sudden fall in the quantity of suspended matter. 

 Between Cape St. Mary and Cape St. Vincent tne 

 water changes to the deepest indigo, a further diminution 

 of the suspended matter being the concomitant pheno- 

 menon. 



We now reach the remarkable group of rocks called 

 the Burlings, and find the water between the shore and 

 the rocks a strong green ; the home examination shows 

 it to be thick with fine matter. Fifteen or twenty miles 

 beyond the Burlings we come again into indigo water, 

 from which the suspended matter has in great part dis- 

 appeared. Off Cape Finisterre, about the place where 

 the ' Captain ' went down, the water becomes green, and 

 the home examination pronounces it to be thicker. Then 

 we enter the Bay of Biscay, where the indigo resumes 

 its power, and where the home examination shows the 



