Madame Sontag's voice is well preserved. If its lower notes have lost a little of their fulness and freedom, as is always the case with soprano voices, the upper notes still retain their roundness and their charm. Her powers are hardly less exquisite than when she was twenty years old; her execution has lost nothing of that marvellous flexibility which was then its characteristic; and, with the slightest awakening of the imagination, we recognise to-day in Madame Sontag the finish, the charm, the placid and serene expression which have distinguished her among the eminent vocalists who have astonished Europe in the last half century. Received with distinction by audiences of the highest fashion, who were drawn together by the rumor of her greatness and her misfortune, she has sung with great success many selections from her former _repertoire_. Among these none have attracted more attention than Rode's Variations, a sort of musical tapestry, brought into fashion by Mad. Catalani, and upon which Mad. Sontag has embroidered the most intricate and charming arabesques. An ascending scale launched out at lightning speed and flashing upon the ear like a ribbon of fire, has excited the liveliest transports. The celebrated vocalists of the nineteenth century may be divided into three groups, very diverse from each other. In one we find those who have shone by the expression of strong passion, and by elevation of style, such as Mad. Pisaroni, Mad. Pasta, and Mad. Malibran; in another, those wonderful syrens who exhale in a merry peal of radiant laughter, such as Marcolini, Mad. Persiani, and many others. It is between these two extreme groups that we place Mad. Maineville-Fodor and Mad. Sontag, who have possessed all the seductions of a rich and graceful vocalization, without exhibiting either the transports of passion or the spontaneous outpourings of gaiety. Accordingly, they have flourished long, for they have never undergone those paroxysms which break and consume a feeble woman as a diamond is devoured in the crucible of the chemist. We delight to bring Mad. Sontag before our mind's eye decked in a white robe, listening to harmless thoughts, moving placidly through a leafy vista, and in her bosom a cluster of Forget-me-not. HENRIETTE SONTAG IN FRANKFORT. BY LOUIS BOERNE.