Glass Thermometer 0-100 Degree C

The alcohol thermometer or spirit thermometer is an alternative to the in-glass thermometer and has similar functions. The contents of an alcohol thermometer are less toxic and will evaporate quickly. The ethanol version is the most widely used due to the low cost and relatively low hazard posed by the liquid in case of breakage.

An organic liquid is contained in a glass bulb which is connected to a capillary of the same glass and the end is sealed with an expansion bulb. The space above the liquid is a mixture of nitrogen and the vapor of the liquid. For the working temperature range, the meniscus or interface between the liquid is within the capillary. With increasing temperature, the volume of liquid expands and the meniscus moves up the capillary. The position of the meniscus shows the temperature against an inscribed scale.

The liquid used can be pure ethanol, toluene, kerosene or isoamyl acetate, depending on manufacturer and working temperature range.
Since these are transparent, the liquid is made more visible by the addition of a red dye. One half of the glass containing the capillary is usually enamelled white or yellow to give a background for reading the scale.