Question

make a lactometer with ballpoint refill what Do you do to make the refill stand vertically straight

Answer 1

Lactometer is an instrument which is used to test the purity of milk.

Principle : Works on Archimedes Principle

TO make a lactometer with ball point refill, follow the given steps :

1.Take an empty ball pen refill.

2. Refill should have a metal point at the bottom.

3.Take  a boiling tube and fill it with water.

4.Put the refill in the water with metallic point.

5.To make the refill stand in water, insert a small eraser piece in the refill at the centre.

6.Mark the point  with marker up to which the refill is above the water.

7. Now, empty the boiling tube with water and fill it with milk.

8.Again put the refill in milk and mark the point which shows the part which is above the surface of milk.

9.Further we can add , milk water mixture in the boiling tube and repeat the same step 8. 

10. we can now compare and test whether water is added to milk or not.

All the best for the Improvised Lactometer you are going to do.

Answer 2

Lactometer is the special instrument used to testified whether a milk is pured or not.
milk is testified on the basis of density with it.
In order to make a ball point refill "a lactometer" first of all take a refilled ball point having metal tip at bottom Then take a boiling tube filled with water. After that by using metal point place the refill into the water . Then insert a piece if eraser in to the refill in order to make refill stand in water , Note the point of refill above water.
after that clean that boiling tube and poured the milk in to it and then put refilled into it.
note the point of refill again .
Now you can easily compare values for milk and water.