We will discuss here about the methods of measurement of volume of a substance. Liquid substances do not have any specific shape. It takes the shape of the container in which it is kept. So we cannot measure liquid with a measuring tape or a scale. But we can measure the volume of a liquid very easily.
We know the volume of a substance is the space occupied by it. The unit used for measuring the volume of a liquid is liter (I). We use this unit to measure volume of milk, water, etc. To measure the volume of smaller quantity of liquid like medicines, chemical substances, etc., we use milliliter (ml). It is a very small unit of volume. One thousand milliliters make a liter.
Liquid occupies the space in any container it is kept. So we can measure the volume of a liquid with the help of a graduated container. It is called a measuring cylinder. It is a glass jar with a flat base having equal diameter all along its length. The wall of the cylinder is graduated in milliliter.
To measure the volume of a liquid we have to pour the liquid within the measuring cylinder and observe the upper surface of the liquid perpendicularly. The mark in the graduation that coincides with the top level of the liquid, indicates its volume in milliliter. With different measuring cylinders we can measure liquid from 50 ml to 500 ml.
To measure volume of petrol, kerosene, etc., typical cone shaped measuring containers are used. Such containers are of different sizes and are used to measure different quantities of liquid. The size of the containers may vary from 500 ml to 5 liters.