In 1851, in one of the most famous publications in the history of thermodynamics, On the Dynamical Theory of Heat, with numerical remits deduced from Mr JOULE'S equivalent of a Thermal Unit. etc., Thomson (later Lord Kelvin) pronounced his version of the 2nd law as follows: "It is impossible, by means of inanimate material agency, to derive mechanical effect from any portion of matter by cooling it below the temperature of the coldest of the surrounding objects."

Some 45 years later in 1897, Planck in the 1st edition of his book Treatise on Thermodynamics he phrased the 2nd law as: "It is impossible to construct an engine which will work in a complete cycle, and produce no effect except the raising of a weight and the cooling of a heat-reservoir," without even hinting at an inanimate material agency in this formulation.

I assume in 1851 it was still normal to accept some form of vitalism, hence Thomson's restricting his 2nd law to inanimate agencies but not any more 45 years later. What and when the change happened to reject vitalism in physics? When did Thomson himself reject vitalism explicitly, did he ever?