China's manufacturing may contract at a slower pace in August as the world's second-biggest economy weathers slumping global confidence.   A preliminary reading of 49.8 for a manufacturing index released by HSBC Holdings PLC and Markit Economics on Tuesday compares with a final reading of 49.3 for July. The final August number is due on Sept 1. A reading below 50 indicates a contraction.   The data suggests that growth in China is moderating rather than collapsing and the s...