What is the significance of the lines beginning, "Thou art a soul in bliss; but I am bound Upon a wheel of fire, that mine own tears Do scald like molten lead..."?

When Lear regains consciousness in Cordelia's tent he thinks he is still dead and that she is an angel. His imagination of being dead and in hell is so vivid that he can still see the instruments with which the demons torture the condemned souls. His own form of torture is being bound on a burning wheel and turned around and around like an animal being barbecued over a blazing fire. This metaphor reflects Lear's mental suffering, which he has been experiencing throughout the play. The genius of Shakespeare is evident in the words, "...that mine own tears do scald like molten lead." This contains an alliteration of L sounds in "scald," "like," "molten," and "lead." It is highly unusual to use L sounds in alliteration, but it is especially effective here because it suggests the slow, relentless dripping of hot molten lead. There are also three L sounds in the preceding words, "soul," "bliss" and "wheel," so that there are actually seven L sounds in the sentence. The words "wheel" and "fire" help to suggest the image of a turning wheel. The word "fire" can sound like two syllables, and coming right after "wheel," it is intended to augment the image of a turning wheel with the addition of flames. Instuments of torture similar to the one Lear describes may have actually existed in his time, but he is suggesting that the demons have much better technology down below. Lear has certainly come a long way down from the proud man he was in the opening scene of the play.