188 
agree, and in what they differ. Among other things he observes, that extreme 
cold extinguishes the light of shining wood, as appeared when a piece of it was 
put into a glass tube, and held in a frigorific mixture. He also found that 
rotten wood did not waste itself by shining, and that the application of a 
thermometer to it did not discover the least degree of heat. 
There is a remarkable shell-fish called Pholas, which forms for itself holes 
in various kinds of stone, fee. That this fish is luminous, was noticed by 
Pliny; who observes, it shines in the mouth of the person who eats it, and 
if it touch his hands or cloaths, makes them luminous. He also says that 
the light depends upon its moisture. The light of this fish has furnished 
matter for various observations and experiments to M. Reaumur, and the 
Bolognian academicians, especially Beccarius, who took so much pains with 
the subject of phosphoric light. 
M. Reaumur observes, that, whereas other fishes give light when they 
tend to putrescence, this is more luminous in proportion to its being fresh; 
that when they are dried, their light will revive if they be moistened either 
with fresh or salt water, but that brandy immediately extinguishes it. 
He endeavoured to make this light permanent, but none of his schemes 
succeeded. 
The attention of the Bolognian academicians was engaged to this subject 
by M. F. Marsilius, in 1f 24, who brought a number of these fishes, and 
the stones in which they were inclosed, to Bologna, on purpose for their 
examination. 
Beccarius observed, that though this fish ceased to shine of itself when 
it became putrid; yet that in its most putrid state, it would shine, and make 
the water in which it was immersed luminous, when it was agitated. Galeatius 
and Montius found, that wine or vinegar extinguished this light; that in 
common oil it continued some days ; but in rectified spirit of wine or urine, 
hardly a minute. 
In order to observe in what manner this light was affected by different 
degrees of heat, they made use of a Reaumur’s thermometer, and found that 
water rendered luminous by these fishes increased in light till the heat arrived 
to 45 degrees; but that it then became suddenly extinct and could not be 
revived. 
In the experiments of Beccarius, a solution of sea-salt increased the light 
of the luminous water, a solution of nitre did not increase it quite so much. 
