|MadSci Network: Cell Biology|
i think that the best way to add these solution to your samples is to do it prior to the slide preparation. if yout like to do it on the slide than it is difficult to get a homogenous distribution of your salt without disturbing the whole preparation.
Another solution is using an inverted miscrocope. in this way you will
have your blood suspension a petri dish or culture plate and is it quite
easy to add your salt solutions
I hope these answers will help.
Try the links in the MadSci Library for more information on Cell Biology.