Many people may think that the liquid measuring process is more difficult than solid substance measuring process because of the liquid surface tension.
The gravity pushes down on the surface of the liquid, but at the edges of the container it is found that the liquid surface tension gently pulls it up the sides.
For that reason, you will find that the top of the liquid is not flat, but it has a convex shape which is frequently difficult for measuring when the liquid volume that you want to measure is relatively small.
Moreover, if you want to get accurate measurement of a liquid, it is very important for you to locate the meniscus.
This is the lowest part of the correct shape which is made by the liquid in the measuring vessel.
Also, it is very important for you to have the water surface at the eye level.
When you are looking at the liquid from above or below, you will know that the meniscus position will slightly shift and give the inaccurate reading.
Furthermore, you should locate the line which marks the measurement that you want to take.
In this step, you should hold the vessel at the eye level and then you need to locate the meniscus.
After that, you have to add or remove the liquid as needed with the dropper or something which can add or subtract the small volumes from container.
You must do this until you find that the level of meniscus is the level with the line of the desired volume.
In addition, if you fail to locate the meniscus can indicate that the vessel you are measuring in is dirty and incapable to hold the liquid surface tension.
On the other hand, the different types of the liquids contain different surface tensions so that the meniscuses are also different.