On the assumption that the relative volatilities, a, and the molal overflow are eonstant ln a given column section, a comparatively simple and rapid method of performing multicomponent fractionation calculations is developed. The proposed method enables one to calculate by means of tabulated values of the functions B1 and lC2 directly the composition on the nth plate without going through calculations of the compositions on the intermediate plates. This ls done by means of the simple equations : %I '$qj#, +QFd@r -l) Es (in rectifying section) z,,, =+E1 +@a"lVl) Es (instrippingsectlon) E, and q are functions of the equilibrium ratio, reflux ratio, and the number of the plate. Their valuea may be obtained from suitable tables or plots. It ls believed that the proposed method offers considerable shnplicillcation iu multicomponent rectification calculations. The 54 equations are tested and their use demonstrated in two examples. It&mm6-En supposant que les volatilit& relatives, a, et le flux mol&xlaim sont constants dans une section don& de la colonne, l'auteur expose une m&bode comparativement simple et rapide pour effectuer lea calculs dans la s6paration fractionn4e d'un m&nge h plusieurs composants. La mbthode proposk permet, B partir de tables dea valeurs da Ion&ions 6, et Es, de calculer diictement Is composition sur le n&me plateau sans passer par le calcul des compositions sur les plateaux lntermtkliaires. Ce qui se fait par les 6quations simples : x,, =q!fE, + %@r -1) Pt Es (in rectifying section) %I =;Emq + ~m(P,-l) PI E, (in stripping section) El et Es sont des fonctions du taux dVquilibre du reflux et du nombre de plateaux. Leure valeurs peuvent &e obtenuea A partir de tables ou de co&c% approprik. L'auteur pense que la m&bode propoe& pr4sent.e une simplification considerable dans les calculs de la rectillcation de m&ange~ & plusieurs composanto. 11 essaie lea 6quations Anales et dbmontre leur utilisation dans deux exemples. The classical method of solving multicomponent composition close to that of the feed is reached. rectification problems is that of LEWIS and Readjustment of the reflw ratio or of one of the MATHESON [8]. Thii method consists of plate-by-starting compositions (waste or distillate) may be p1at.e calculations starting with the still pot and required to make the compositions " mesh " on continuing up the column until a compition the feed plate. Thii method (as well as its graphical approaching that of the feed is obtained. In a equivalent, the method of LEWIS and COPE [a]) similar way, starting with the composition qf the has the advantage that it may be carried to any distillate, one proceeds down the column until a degree of accuracy and may be easily combined Rectification of multiw3mponent mixtures