I have not played Betry, so I can only go by the walkthroughs.
Here is another one on
GameZebo. When you have the Red Solution, grab the Red Flask from the top of the Cabinet. There is a Green Flask on the desk by the computer, and one on the Chair (Click the chair to turn it around). When you have all 4 Flasks, place them on the Electronic Scale. You must weigh each flask, so empty the green one into the left flasks. When it is empty, make the red flask hold 9mL, and then put 4mL of green back in the flask, equaling a total of 13mL in weight. When you have the correct amount, pour the combination into the Powder sitting on the ledge.
Ana