i88o.] 
On Water and Air. 
ii3 
shown by my excellent friend, Mr. Spedding, and his distin- 
guished and eminent colleague, Mr. Ellis, that nearly fifty 
years prior to the experiment in Florence it had been made 
by Bacon ; and therefore, instead of being called the Flo- 
rentine experiment, it ought really to be called the Baconian 
experiment. 
In our last ledture we had some experiments illustrating 
the tenacity of water. Well, this tenacity is enormously 
increased if you repel the air from the water. Take a flask 
of water, heat it over a spirit-lamp, and you will always 
find, after a certain time, bubbles coming from the water, 
and condensing like bubbles of steam. They are small 
bubbles of air held in solution by the water. If you rid the 
water of this air, if you get the air from between the parti- 
cles of water, you enormously increase its tenacity, and it 
has very many peculiar properties when it is thus rid of the 
air. For instance, here is a quantity of water contained in 
this tube, and if I bring the water into one end of the tube 
and turn it down you hear that the water rings like a solid. 
[In this experiment the water was contained in a glass tube 
called the water-hammer, from which the air had been ex- 
pelled.] This is water that has been deprived of its air by 
boiling. The water was placed in this tube, and one end of 
the tube was drawn out nearly to a point, for the steam and 
air to escape through the orifice, and after a certain amount 
of boiling the orifice was hermetically sealed. This water, 
as I have said, has far greater tenacity than ordinary water, 
and in order to demonstrate this I have here a glass V-shaped 
tube (a b c, Fig. 4) which illustrates a series of experiments 
made by a distinguished man in Belgium, M. Donny. He 
showed that when water is deprived of its air the tenacity 
of the water is enormously increased. You see that, as I 
turn the tube, the water rests at the same level in the two 
legs of the tube. If I hold the tube in one way the water 
goes into one leg, and if I hold it in another way the water 
goes into the other leg. Now this tube has been deprived 
of its air in a somewhat similar manner to the water- 
hammer, as it is called, that I have just shown you, and 
you hear that the water rings when I bring it into contact 
with the interior surface of the tube. 
Now what I want to show you is that, if I really bring 
that water into close contadt with the interior surface of the 
tube, it will not flow back : there it will cling, and the par- 
ticles of water will so hold on to the glass that the water 
will not flow from one end to the other. When I first turn 
down one end of this tube you observe that there is a little 
