In 1867 he was appointed as a commissioner representing California at the Exposition Universelle (Paris Exposition). His report on the precious metals, forming one of the government volumes on the Paris exposition of 1867, is full of valuable information. He was the first to recognize the tellurides among the products of California, and was also the first to draw attention to the platinum metals associated with the gold-washings of that state. Some of his findings when reported to Whitney, enmeshed the two in continued feuds over primacy of geologic discoveries. Scientific conflicts between these scientists, especially over priority in recognizing potential oil fields tarnished their reputations. Blake, being less of a self-promoter than Whitney, fared poorly in the conflict. Returning to New York and Connecticut, he was a founding member of the American Institute of Mining Engineers (1871) and contributed to its conferences and "Transactions" throughout his career.