104 EMISSION OF LIGHT BY 
death, none perhaps so vividly as that of the Pholas, 
a mollusk well known to those who reside on the 
coast. That this mollusk was luminous after death 
was known to Pliny, who said that it shone in the 
mouths of the persons who ate it; and among 
the moderns, Réaumur, Beccaria, Marsilius, Galea- 
tus, and Montius have studied its phosphores- 
cence. f 
Beccaria had the curiosity to ascertain how 
the hght of putrescent fish, and that of the dead 
pholas, affected different colours, and for this pur- 
pose he placed in the light emitted, pieces of dif- 
ferent coloured ribbons. The white came out 
brightest, next to that was the yellow, and then 
the green; the other colours could hardly be per- 
ceived. ‘he same experiment was repeated, with 
similar results, on trying coloured liquids in glass 
tubes. We have here then another instance of the 
predominance of yellow tints over the others in 
cases of phosphorescence. Indeed Sir Isaac New- 
ton, who first decomposed light into the seven 
rays of the spectrum, says, “The most luminous 
of the prismatic colours are the yellow and the 
orange ; these affect the senses more strongly than 
all the rest together.” 
These experiments of Beccaria were made chiefly 
with the Pholas. A single pholas rendered seven 
ounces of milk so luminous that the faces of per- 
sons might be distinguished by it, and it looked 
as if transparent. 
