Murphy is clearly right on this subject. "Savings" means uhm well saving, (or preserving if you will) something, in this context meaning the claim on consumer goods. That is something that can be achieved by any act that refrains from consumption, including for example holding paper money, holding gold, holding stocks or holding bonds or bank deposits.
But isn't there a difference between putting money in a jar and using it for capital expenditure. Yes, but that's why you have words like "investment" and "capital expenditure", to differentiate between different forms of savings.
As Murphy points out, Wenzel's definition creates the absurd situation where someone who has deposited money in a bank really doesn't know whether or not he has saved until he knows whether or not it has been lended. And indeed that's not really sufficient, as he also must know whether or not the loan has ceteris paribus causally made the borrower invest in capital goods. It furthermore would imply that if the borrower didn't use it for capital expenditures, but for consumer expenditures, then people who saves their income really aren't saving. What is really going on is that the people lending (depositing) money to the bank are saving while the people borrowing from the bank are dissaving, but if you define savings as "capital expenditure" you would not be able to understand that these transactions involved some people saving and other people dissaving.