42 
tion when at Edinburgh in 1850. For a tree in the neigh- 
bourhood having been struck and specially shattered into 
thin plates of wood, during the week of congress, was formally 
examined by a deputation of the Association, and the light- 
ning was held to have exploded the watery matter of the 
sap-vessels. 
(2) That water is a far more powerful exploder than gun- 
powder if you can get it (the water) to explode at all, is now 
experimentally proved by Professor Osborne Keynolds’s 
electrical experiments; and did occupy my attention many 
years ago, on comparing the far larger increase of space 
occupied by exploded water in the shape of steam, than by 
exploded gunpowder in the shape of its permanent gases. 
The difficulty however is, to get the water to explode, 
and not to pass off merely into steam ; a difficulty well illus- 
trated by any and every accession of dampness to gunpow- 
der fired in the usual way, decreasing, instead of increasing, 
the gunpowder’s explosive force. 
In order to try to explode water, at that time, I melted a 
large ladle full of lead ; put upon the fiuid and almost red- 
hot surface a drop of water and tried various devices to 
bring it under the influence of the heat ; but even when 
forcibly attempted to be pushed under the melted lead, the 
water ran with vehemence up the substance of the wooden 
probe employed, and refused to have anything to do with 
the fluid lead, which consequently remained undisturbed. 
But when I next took a smaller iron ladle, put a drop of 
water on the bottom of it, and gave therewith a little pat 
to the surface of the melted lead, instantly the whole con- 
tents of the great ladle were scattered to the winds, and 
only a few grains were recovered. Explosion of water had 
apparently taken place with excellent effect. 
Then came a question as to repeating such an explosion 
