How can I recognize the salty layer???
You should really study some organic chemistry before SWIY starts to synthesize 2C-B. It's definately not the easiest synthesis to start with. You will encounter extraction and washing all the time while cooking. Master the theory on extraction and washing before you proceed, it will save you a lot of money on chemicals.
I can recommend James W. Zubrick's book "The Organic Chem Lab Survival Manual". I will give you some free hints you can find in this excellent book.
I quote "
Never, never,never,never,
ever throw away any layer, until you are absolutely sure you'll
never need it again. Not very much of product can be
recovered from the sink trap!"
This may sound silly but is is very useful!
I think it is better to call the "salty" layer the aqueous layer. [Extraction can only be done between two immiscible liquids, organic layer/aqueous layer] To know which layer floats on top you need to know what the density of your organic solvent is. The lighter layer floats on top of the heavier layer. Logic isn't it? You can assume that a dilute NaCl solution has the same density as pure water (about 1g/ml @25°C). Check the density of your organic solvent and you know if the layer will be on top or not.
An experimental way I quote directly from Zubrick's book:
""Which layer is the water layer?" This is so simple, it confounds everyone. Get a small (10x75 mm) test tube and add about 0.5-1.0 ml water. Now add 2-4 drops of the layer you thinks is aqueous, and swirl the tube. If the stuff doesn't dissolve in the water, it's not an aqueous (water) layer. The stuff may sink to the bottom, float on top, do both, or even turn the water cloudy! It will not however, dissolve."
Good luck and study hard!