It is great to see someone actually checking the references  The description in the article is my personal editorial freehand description of the equation on page  No reference Indeed I did not try to use Clausius terminology My aim was to present his idea in present day language If you feel like improving on it I will not be offended I referred to the  paper to in order to defer to Clausius priority in stating the law I would still prefer to quote the  paper rather than the  one I have not tried to present the nearly simultaneous  version by Rankine but I would not object to seeing that done as well though I think it perhaps unnecessary