Augustine on Purgatory
In his dread of those more serious misfortunes, the speaker disregards this life which causes him to weep and groan with its misery, and makes his entreaty: Rebuke me not, O Lord, in thy indignation [Psalms 38:1]. Let me not be among those to whom thou wilt say: Depart into everlasting fire which was prepared for the devil and his angels [Matthew 25:41]. Nor chastise me in thy wrath [Psalms 38:1]. Do thou cleanse me in this life and make me such that I shall have no need to pass through the purifying flames prepared for those who will be saved yet so as by fire [1 Corinthians 3:15]. Why? Is it not because in this world they are building upon a foundation of wood, hay, stubble? If they constructed with gold, silver, precious stones, they would be safe from both kinds of fire, not only from the everlasting fire which will torment the wicked forever and ever, but also from that which will purify those who are to be saved by fire. For we are told: He himself shall be saved, yet so as by fire [1 Corinthians 3:15]. And because of the phrase shall be saved, that fire is not taken seriously enough. Clearly, although they will be saved by fire, yet that fire will be more grievous than anything a man is capable of bearing in this life.
Augustine: Discourse on Psalms (Enarrationes in Psalmos) 37.3
English translation from Ancient Christian Writers, Vol. 30, page 330-331
While Augustine did not use the word purgatory he distinguished two kinds of fire, the everlasting fire that will torment the wicked forever and the purifying fire.