Danbury-based Praxair saw big gains in the first quarter of 2007. The company is the largest industrial gasses provider in North America. First-quarter net income of $265 million rose 18 percent from the first quarter of 2006, and diluted earnings per share grew 19 percent to 81 cents. Sales in the first quarter increased to a record $2.2 billion. Sales grew 8 percent from the same quarter in 2006.