what were the economist opinions regarding the trade without cost??
Free trade provides a net gain for society.
Free trade
Although it creates winners and losers, the broad consensus among economists is that free trade provides a net gain for society. 
who is elias abraham rosenberg? An adviser and friend of King Kalākaua. which kingdom did the latter reign? The Kingdom of Hawaiʻi. was he into politics? Yes, before coronation he was a member of the Privy Council of State and a member of the House of Nobles. what was his role in promoting education? He started the Education of Hawaiian Youths Abroad  program. what was the program about? It was a government -funded educational program in which Hawaiian students were selected for enrollment in a university or apprenticeship to a trade, outside the Kingdom of Hawaii. can you tell me something about the treaty that got extended? It was a free trade agreement between the Hawaiian kingdom and the United States of America. were there any specific product that come under this treaty? yes, sugar and other products.
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Free trade [SEP] Economist opinions
The literature analysing the economics of free trade is rich. Economists have done extensive work on the theoretical and empirical effects of free trade. Although it creates winners and losers, the broad consensus among economists is that free trade provides a net gain for society. In a 2006 survey of American economists (83 responders), "87.5% agree that the U.S. should eliminate remaining tariffs and other barriers to trade" and "90.1% disagree with the suggestion that the U.S. should restrict employers from outsourcing work to foreign countries". Quoting Harvard economics professor N. Gregory Mankiw, "[f]ew propositions command as much consensus among professional economists as that open world trade increases economic growth and raises living standards".