Centinel
Tenther
Appropriations made by Law
explain the above
Okay, I'll try to explain more fully.
The states created the federal government as their agent, and they delegated to this agent of theirs certain powers. These powers are listed in Article I, section 8. For example, in this section one will find a power to tax, a power to mint coins, a power to declare war, a power to establish a navy, etc.
So we have a federal government to which a small set of power has been delegated. At the end of art I, sec 8, one can find a clause that gives congress the power to actually write the legislation necessary to carry out its delegated powers. So, for instance, congress could write a law the purpose of which might be to, say, build a mint and set up the rules for its operation.
The clause to which you refer is not a delegation of power. It is a restriction of power, in that it places limits on how and when funds may be withdrawn from the treasury. As it states, funds may only be withdrawn from the treasury when congress has passed a bill authorizing the withdrawal of such funds.
So, for example, in legislation that carries into execution one of its enumerated powers, congress (only the house, actually) will include language that appropriates the funds necessary to execute the legislation. So, in my example above, if congress writes legislation to establish the operation of a mint, the bill would appropriate funds to that end. Only with this appropriation can funds then be withdrawn from the treasury.
So my point is that the clause you cite is does not represent a power delegated to congress, but simply restricts withdrawals from the treasury to those appropriated in legislation. One might look upon it as an anti-fraud provision.