170 Scientific Intelligence. -^Chemistry. 
8. Light emitted during the Friction of Crystals. — It is well 
known that many crystallised substances, when rubbed together, 
or broken across, give out a light more or less intense. It is 
said by Olof Wasserstrom, in the Transactions of the Swedish 
Academy for 1798, that the phosphorescence of the sea, in 
northern countries, may sometimes be owing to the small and 
very thin needles of ice, which almost cover the surface of the 
sea, being broken in pieces by the agitation of the waves, and 
thus emitting a light, which may assist in giving the lumi- 
nous character to the water. He also affirms, that masses of sea- 
ice, when violently struck, give out light. The following pas- 
sage from Becquerel, on the development of electricity by pres- 
sure, in the Ann. de Chim. 22. p. 5., is of the same general na- 
ture Considering the increased development of electricity in 
foodies, by the augmentation of pressure, ought we not to refer 
to this cause certain luminous phenomena, of which the origin is 
as yet unknown ? For instance, it is said, that, in the Polar 
seas, it frequently happens that the blocks of ice which strike 
together evolve light. These enormous blocks arriving one 
against the other, with considerable motion, will be submitted to 
great pressure, and thus the two blocks be placed in two differ- 
ent electric states. At the moment the compression ceases, the 
two fluids will recombine, in consequence of the conducting 
power of the ice ; and may not the light disengaged be the re- 
sult of the combination of the electric fluids ? Iron, submitted 
to successive blows, also becomes luminous : Are not the same 
phenomena of pressure produced here, as when two masses of 
ice strike together ? 
9. Benzoic Acid in Grasses.— It is known that Scheele de- 
tected benzoic acid in the urine of newly born children ; and 
that, more lately, chemists have found the same acid in the 
urine of some graminivorous animals, as the cow, the horse, and 
in that of the rhinoceros. These facts naturally lead us to in- 
quire the source of this acid in the animal kingdom. Some 
conjecture that it is formed by the organic powers of the ani- 
mals ; while others maintain that it has been derived from with- 
out. This latter opinion has been in part confirmed by some 
late experiments of Vogel. Pie found this acid in an uncom- 
