What is Spirit-Baptism?

So too were all the water-baptisms administered by John the Baptist. He constantly preached to his Hebrew converts that Jesus, unto Whom he was baptizing, would Himself soon come — and baptize with the Holy Spirit and with fire! Lk. 3:16 cf. Acts 1:5 & 2:1f.

There were only three or four Post-Pentecost "out-tricklings" of the Spirit. Acts 8:12-18; 8:37?; 10:44f cf. 11:15f; & 19:1-6. These were all only in respect of gathering the 'first-fruits' of Non-Hebrew Christians — and ingrafting them into the new Church Visible alias Christ's storehouse for His wheat. Mt. 3:11f & Lk. 3:16f.