Thomas Chalmers' Interests . .

One could enumerate a great number of these - let's start with the obvious one, common to most Godly ministers of his time - Books!
In a letter to Grace, a daughter, he mentions some of his favourites for personal devotions.

Lives - of Brainerd and Doddridge
Bridges on Psalm 119
Horne on the Psalms
Doddridge's Family Expositor
Scott and Henry's Bibles

And for solid reading, 2 hours at a time,

Evidences of Christianity - (Keith?)
Symington on the Atonement
Owen on the Work of the Holy Spirit
Owen on the Person of Christ
Reid's, Stewart's and Brown's Works
Foster's Essays
Chalmers on Endowments and Establishments.

Chalmers was also very keen on Mathematics and Chemistry - his enthusiasm nearly lost him his first job at the University of St. Andrews, in Fifeshire, Scotland. He was, in fact, removed from it but was replaced after demonstrating that his enthusiasm actually helped his pupils to learn, and engaged their respect and affection.

As a good evangelical, he repudiated the claims of so-called "hyper-Calvinism", as instanced by the quote here reproduced from his Essay on Guthrie's Work on "The Christian's Great Interest"
"Nor is his clear and scriptural exhibition of the dispensation of grace less fitted to guide the humble inquirer into the way of salvation. As a faithful ambassador of Christ, he is free and unreserved in his offers of pardon and reconciliation, through the death and obedience of Christ, to the acceptance of sinners; but he is no less faithful in stating and asserting the claims of the gospel, to an unshrinking and universal obedience, and to an undisputed supremacy over the heart and affections"

Chalmers also had a great enthusiasm for Education - of the masses. See his submission to the government, by their request, here.

Another theme involving much of his time, was that of grants of land by landowners, which were not forthcoming after the Disruption, which these hoped could be reversed with time. See here his paper on this.

Chalmers was always conscious of his besetting sin - intemperence, especially in diet. This made him extremely abstemious in practise as he sought to be obedient to his Master

Another great interest was Social Reform. He started Sabbath Schools in his district, he supported the formation of the British and Foreign Bible Society with all the (considerable) power at his command. He further investigated the working of Relief to the Poor, with some remarkable, but un-arguable conclusions. See item here.