In Shulgin's procedure in Tihkal (#26) for making LSD, he starts out by doing an alkaline hydrolysis of Ergotamine Tartrate. After refluxing the alkaloid in the potassium hydroxide solution, dilute H2SO4 is added, which precipitates the Lysergic Acid, and one presumes, some Potassium Sulfate.
He then extracts the Lysergic acid into Ammoniated Ethanol, and then removes the Ethanol under vacumm.
However, he next "dissolves the residual solids in 50 mL of 1% aqueous ammonia, and acidfies the solution as before with 2.5 N H2SO4" to re-precipitated the Lysergic Acid.
My question is, what is the purpose of this second step of dissolving and re-acidfying? Why not just use the Lysergic Acid after evaping off the Ammoniated Ethanol?