Of all the things of Nature WATER must rank as one of the strangest. It is indeed an incredible STUFF. Its behavior is uncommon and its properties serve man in extraordinary ways.
A. We first show the changes which occur when we consider ONE gram of ice at 0°C to which heat energy is conveyed. We note that in CHANGE OF STATE no change in temperature takes place. The Heat energy therefore must go into "tearing" the bonds which hold the stuff together. We discover from this sequence of operations that the liquid state is more "energetic" than the solid state and the vapour (vapor) state - or gaseous - more energetic than the liquid.
B. We observe the behavior of a thermometer in a beaker of ice. As the ice melts we might - if we did not know better! - we might expect the thermometer to show a rise. But it does not. As long as any vestige of ice remains the thermometer will read 0°C - if this is the temperature of the ice to begin with. Change of state - NO change in temperature.
C. Consider a glass of ice-and-water — so called ice-water - resting on the table. Let the vessel be FULL absolutely full. That means that some ice is ABOVE the level of the water. Now as time goes some ice melts. Question: Will the water run over — will the glass - as we say - overflow? Answer: NO. Since 1. 1 cmJ of ice = 1.0 cm of water. Most of the ice of an iceberg is below the level of the sea. Question that comes to me suddenly: Is an iceberg salty?
D. We take a huge block of ice - support it on a platform - and put around it a wire loaded on both ends. The wire in due course 'sinks" into the ice - cuts into the ice. .The pressure of the wire melts the ice - the water which arises again freezes. This process is called regelation. We encounter this when we make a snowball by squeezing the snow in hand. The snow melts under the pressure; the water refreezes and we have an "ice ball".
E. Here is a demonstration for engagement at the DINNER TABLE. We have ice water served to each guest. Each guest is supplied with a tiny length of string - three inches or so. The problem is this: Get out a hunk of ice - a cube of ice - using the string as the agent for lifting out the ice. Some try to tie the string to a cube of ice! But it is too short for this! SOLUTION: Lay the string atop a hunk of ice. Gently pour on the string some fine salt from the salt shaker. Wait a few seconds. The salt melts some of the ice immediate to the string. This ice water at once refreezes. The string is thereby fixed to the ice. Now gently pull up on the free end of the string.
F. We show an array of photographs of men who gave us abundant knowledge of these things. It is very important to have a mind to MEN AND EVENTS and to the national origin of these people — Maxwell — a Scot — Joule an Englishman — Bernoulli a Swiss — and so on.
Demonstrations in Physics was an educational science series produced in Australia by ABC Television in 1969. The series was hosted by American scientist Julius Sumner Miller, who demonstrated experiments involving various disciplines in the world of physics. The series was also released in the United States under the title Science Demonstrations.
This program was a series of 45 shows (approximately 15 minutes each) on various topics in physics, organized into 3 units: Mechanics; Heat and Temperature / Toys; and Waves and Sound / Electricity and Magnetism.