This is a slow blues version of the well-known Christian hymn written by Philip Paul Bliss (1838–76). It was arranged as a solo for bass trombone and band, giving the instrument a rare chance to be the featured soloist.
 
Audio demo: https://soundcloud.com/user-565396545/i-am-so-glad-bass-trombone
 
Duration: Approx. 3.25 minutes
 
Difficulty Level (Band): Medium
Soloist: Medium
 
This PDF download includes the full score and parts. 
 
Sheet music available at www.brassband.co.uk (UK) or https://satradecentral.org (USA)