why do not use water to make a liquid-in-glass thermometer?

Actually, alcohol also wet glass and colourless, but it is commonly used in making a thermometer.

Water is NOT suitable mainly because,

1. The specific heat capacity of water is too high.
i.e. it needs very large amount of energy to raise its temperature.

2. It has no temperature-dependent property.
e.g. its volume will expands below 4 degree Celcius

3. It is a very good thermal insulator.
so it responses to the temperature change extremely slow.

all of the above have the idea but miss one thing very important

WATER EXPENSION IS NOT LINEAR

at 4 degree it have highest density, but between 0 degree and 4 degree its vloume is increasing, fm 0 to 100 degree is also increasing in volume, so in same indication you may endup with 2 possible temperature, so it is not a good sustance to make thermometer.

2007-09-07 12:32:28 補充：
sorry i have not seen mr. jc100shiki have already mentioned this point, my apology...