[Separation of some compound drugs by the method of column chromatography. II. Separation of 1-N-methylpiperidyl-(4')-3-phenyl-4-ethylpyrazolone-(5) (piperylone) from sodium (4-methylamino-2,3-dimethyl-1-phenylpyrazolone-5) salt of methane sulfonic acid (pyralgin)].