* Each drop of reagent added should be mixed with the solution before the next drop is added.
* Observe the effect of each drop of reagent as it is added and mixed into the solution.
* When a test tube is less than half full, mixing can usually be accompanied by shaking or flicking the tube. • Shaking a closed tube with or finger results in thorough mixing of the contents, but danger of contamination from the cork or injury to the finger, making this technique impractical.