FLAT E (XI. 
In 1684, Mr. Cole, of Bristol, described the process of extracting 
the purple of this shell, in the Philosophical Transactions. His ac- 
_ count is as follows: 
«* The Shells being harder than most of other kinds, are ‘to be 
broken with a smart stroke with a hammer, on a plate of iron, or firm 
piece of timber (with their mouths downwards) so as not to crush the 
body of the fish within; the broken pieces being picked off, there 
will appear a white vein, lying transversely in a little furrow, or cleft, 
next to the head of the fish, which must be digged out with the stiff 
point of a horse-hair pencil, being made short and tapering. ‘The 
letters, figures, or what else shall be made on the linnen (and perhaps 
silk too) will presently appear of a pleasant light green colour, and if 
placed in the sun, will change into the following colours, 1. e. if in 
winter, about noon; if in summer, an hour or two after sun-rising, 
and so much before setting; for, in the heat of the day in summer, 
the colours will come on so fast, that the succession of each colour 
will be scarcely distinguished. Next to the first light green, it will 
appear of a deep green, and in a few minutes change into a sea- 
green; after which, in a few minutes more, it will alter into a 
watchet-blue; from that, in a little time more, it will be of a pur- 
plish-red ; after which, lying an hour or two, (supposing the sun 
still shining) it will be of a very deep purple-red, beyond which the 
sun can do no more. 
** But then the last and most beautiful colour, after washing in 
scalding water and soap, will (the matter being again put into the sun 
or wind to dry) be of a fair bright crimson, or near to the prince’s 
colour, which, afterwards, notwithstanding there is no use of any 
stiptick to bind the colour, will continue the same, if well ordered, 
