Upgrading from:

Algebra`Quaternions`

All the functionality in Algebra`Quaternions` is available in the newly created Quaternions Package.

To access functionality from the new Quaternions Package, load Quaternions`:

Version 5.2 << Algebra`Quaternions`;
3 + 2 I + Quaternion[2, 0, -6, 0] - 3*Quaternion[1, 3, -2, 0]