Prof. L. Duthiers on the Purple of the Ancients. 295 
action, a considerable amount of blue always remains; whence in 
nature the final red is never pure, so that the dye always inclines 
more or less to violet. . 
These properties have been placed beyond doubt by the possibility 
of making photographs on silk and cambric, which exhibit a remark- 
able delicacy in detail, combined with great strength of tone. 
_ Ina photograph obtained in this way, the different tints through 
which the dye-stuff passes before becoming violet are more or less to 
be seen, but the deep violet predominates, and represents the black 
of ordinary photographs. 
The changes in the colour of the purple dye-stuff are accompanied 
by the production of a very penetrating fcetid odour, similar to that 
of essence of garlic. The evolution of this odour is as charac- 
teristic of the solar action as the changes of colour, a consideration 
of much importance when we desire to solve the problem to which 
I now turn— What was the primitive colour of the purple stuffs of 
antiquity ? 
At first sight this question seems to be easily answered; but 
when one seeks for a precise signification of the word “‘ purple,” one 
soon becomes embarrassed. If we ask a painter, without telling him 
why, “Be so good as to paint the shade which you would give to 
a purple drapery in a historical painting,” each painter to whom 
the request is made will give a different colour. This is the case 
because no one has an exact idea of the primitive colour, which has 
been gradually modified, and which has now become the red, almost 
scarlet, which many painters understand by the word purple. It 
is only by the interpretation of the phrases of the ancients, and com- 
paring them with direct observations, that one arrives at a solution 
of the difficulty, which would appear to be of great use to art. 
It is enough to remark that the purple colour exists only because 
it has been developed by the sun, in justification of the conclusion 
that the ancients must have been acquainted with this peculiarity, 
as also with that of the development of the characteristic foetid 
odour. Pliny, moreover, speaks of both, and hence it cannot be 
doubted that the purple was produced formerly exactly as at present, 
unless we admit that the animals and their dye-stuff have changed, 
which would be an altogether gratuitous hypothesis. The conclusion 
to which we are driven then is this: the colour was produced formerly 
as at present, under the same conditions and with the same characters, 
so that it ought to have been similar to that which we now obtain. 
In simple and natural experiments the violet has never failed to 
pear, while pure red has always been absent. One is led to con- 
idaie, therefore, that the natural and unmodified purple of the 
ancients was violet, as it is now; for whoever discovered it must 
have made the experiment, as it has been so often repeated, on the 
sea-shore, by breaking a purpuriferous mollusk, and crushing its 
mantle on moist linen which is exposed to the sun. 
Pliny cites Cornelius Nepos, who states positively that at first 
the violet purple was esteemed; and the passages of Plato and of 
Aristotle, which relate to the colour, lead to the same conclusion. 
