The " New York Daily Times" of last Friday contains an article on the caloric steamship, and states that it will soon be ready for trial. It is only intended, it seems, for carrying freight, and is not expected to make the passage in less than 14 or 15 days, between New York and Liverpool. Well, after all, we are not to have a fair trial of superiority, so as to enable us to jwdge of its economy in running with the regular mail steamers. It is asserted that it will use less fuel, and be far more economical thail a steamship. It must be understood that it uses heated air in place of steam as a propelling force. We have seen articles in the " Merchants' Magazine," and in many other papers, holding forth the great advantages and economy in employing heated air as a substitute for steam, but we have not read a solitary statement how this was to be done upon philosophical principles. Some have got the idea from the name of an apparatus connected with the air engine, named a " regenerator," that no heat will be lost, that the same heated air will be used by some hocus pocus process over and over again to drive the engine without extra combustion. It is just about as scientific thus to talk of using heated air as to expect water to run down hill to drive one water wheel, and then up another to leap down a second fall to drive a second wheel. Steam is more economical than heated air, but great improvements have yet to be made in the construction of furnaces of boilers and the economizing ot the heat to prevent so much of it passing away up the smoke pipe.