"The Carmack Amendment of 1906,4 ?? 20(11) of the Interstate Commerce Act, makes carriers liable 'for the full actual loss, damage, or injury * * * caused by' them to property they transport and declares unlawful and void any contract, regulation, tariff, or other attempted means of limiting this liability.5 It is settled that this statute has two undisputed effects crucial to the issue in this cas" . . . . .