By John S. McClenahen By several major measures, U.S. corporations were more profitable during the second quarter of this year than they were in the first. Overall, profits for domestic corporations increased $78.8 billion to a seasonally adjusted annual rate of $788.8 billion, says the U.S. Commerce Department. For nonfinancial corporations, a category that includes manufacturing, domestic profits increased by $64.6 billion during the second quarter to a seasonally adjusted annual rate of $551.1 billion. During the first quarter, profits for nonfinancial corporations advanced only $12.1 billion. Both inflation-adjusted gross corporate product and profits per unit of real product increased during the second quarter. Meanwhile, current-production cash flow -- the internal funds that corporations have available to invest -- increased $78.5 billion in the second quarter, a striking contrast to a $4 billion decrease in the first quarter of this year.