(2) According to the chart, after 1 ~ 5 experiments, the deeper the metal cylinder is immersed, the greater the buoyancy (or the buoyancy is proportional to the depth);

After 6 ~ 8 experiments, the buoyancy of metal after complete immersion has nothing to do with depth.

So the answer is: (1)1n; (2) Under the condition of incomplete immersion, the deeper the metal cylinder is immersed, the greater the buoyancy (or the buoyancy is proportional to the depth);

After complete immersion, the buoyancy of metal is independent of depth (unchanged).