Warren Buffett’s Berkshire Hathaway Inc. said today it will buy specialty chemicals firm Lubrizol Corp. in a deal valued at around $9.7 billion, making it one of the biggest acquisitions in the firm’s history. Berkshire Hathaway has agreed to acquire 100 percent of Lubrizol for $135 per share in an all-cash deal, which has been approved by the boards of both companies. The deal includes about $700 million in net debt. The price represents a 28 percent premium over Lubrizol’s closing price on March 11, and is 18 percent higher than Lubrizol’s all-time high share-closing price. Lubrizol supplies lubricant additives for engine oils, other transportation-related fluids and industrial lubricants, as well as fuel additives for gasoline and diesel fuel.