NOTE OF REGELATION. 55 
it, he concludes that two wet pieces of ice will have the water be- 
tween them frozen at the place where they come into contact.* 
Though some might think that Professor Thompson, in his last 
communication, was trusting to changes of pressure and temperature 
so inappreciably small as to be not merely imperceptible, but also 
ineffectual, still he carried his conditions with him into all the cases 
he referred to, even though some of his assumed pressures were due 
to capillary attraction, or to the consequent pressure of the atmos- 
phere, only. It seemed to me that experiment might be so applied 
as to advance the investigation of this beautiful point in molecular 
philosophy to a further degree than has yet been done; even to the 
extent of exhausting the power of some of the principles assumed in 
one or more of the three views adopted, and so render our knowledge 
a little more defined and exact than it is at present. 
In order to exclude all pressure of the particles of ice on each 
other due to capillary attraction or the atmosphere, I prepared to 
experiment altogether under water ; and for this purpose arranged a 
bath of that fluid at 32° F. A pail, surrounded by dry flannel, 
was placed in a box ; a glass jar, 10 inches deep and 7 inches wide, 
was placed on a low tripod in the pail; broken ice was packed be- 
tween the jar and the pail ; the jar was filled with ice-cold water to 
within an inch of the top; a glass dish filled with ice was employed 
as a cover to it, and the whole enveloped with dry flannel. In this 
way the central jar, with its contents, could be retained at the un- 
changing temperature of 32° F. for a week or more ; for a small piece 
of ice floating in it for that time was not entirely melted away. All 
that was required to keep the arrangement at the fixed temperature, 
was to renew the packing ice in the pail from time to time, and also 
that in the basin cover. A very slow thawing process was going on 
in the jar the whole time, as was evident by the state of the indicat- 
ing piece of ice there present. 
Pieces of good Wenham-lake ice were prepared, some being blocks 
three inches square, and nearly an inch thick, others square prisms 
four or five inches long: the blocks had each a hole made through 
them with a hot wire near one corner ; woollen thread passed through 
these holes formed loops, which, being attached to pieces of lead, 
enabled me to sink the ice entirely under the surface of the ice-cold 
water. Each piece was thus moored to a particular place, and, be- 
* Proceedings of the Royal Society of Edinburgh, April 19, 1858. 
