He took an interest in education and served as a principal of the Serampore College where he taught science and produced the first chemistry textbook in Bengali.

William Ward was on furlough in Britain in 1821 and was looking for someone to work at the Serampore College and visited the Bristol Baptist Academy.

[7][8] The public lectures on chemistry were well attended with nearly 80 to 100 students and he was able to contribute 100 guineas [c] to the mission funds from his class earnings.

[13][14] William Ward died of cholera in 1823 and Mack served in his place as a pastor at Serampore.

He was ordained co-pastor of the Baptist Church in June 1832 and in 1834 he succeeded William Carey as principal of the college.

In 1826 Mack and his wife made a visit to northeastern India and provided Sir William Hooker with a set of plant specimens.

[d][16] In 1836 he visited the Khasi Hills and Assam with his wife after which he suffered from a severe fever and it was thought he might not live.