Industrial and Manufacturing Uses of Shells. 305 



When this juice is applied to linen, by means of a small 

 brush, and exposed to the sun, it becomes green, blue, and 

 purple, and at last settles into a fine unchangeable crimson. 

 Neither acids nor alkalies affect its colour, and it may be 

 conveniently employed in marking linen where an indelible 

 ink is desirable. 



Linton, in his work " On Ancient and Modern Colours," 

 states that the Purpura of the best description were chiefly 

 found on the rocks of Tyre, on the coast of Asia. They 

 were also collected at Mininge on the Graetulan shore in 

 Africa, and on the coast of Laconia in Europe. The 

 colours varied according to the locality in which they were 

 taken. Those from Pontus and Galatia in the north pro- 

 duced a black dye ; in the equinoctial regions a violet hue 

 predominated ; whilst in the south, as at Rhodes, the colour 

 was of a richer red. These purple shell-fish were called 

 Pelagia, and they were distinguished by the district, as well 

 as by the food which the locality supplied. Two hundred 

 Buccina were added to iii Pelagia to make the purple 

 colour so much eulogized by Pliny, and one of the three 

 shades of purple recorded by the ancients. To make a 

 purple dye, they also mingled several varieties of shell-fish, 

 adding nitre, urine, water, salt, and fuci. But the dye from 

 the Buccina required only pure water. 



Experimental investigations in zoologj' showed that the 

 tint of the purple varied in accordance with the nature of 

 the haunt in which the shell-fish was found. Thus, when 

 it lived among seaweeds or mud, the juice it contained 

 was comparatively worthless; when amongst pebbles, its 

 quality was much improved ; and it produced the richest 

 purple when the food and locality of the fish were of varied 

 materials. Researches carried still further proved that, to 

 produce the richest and most postly dye which art could 

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