Transaction interpretation as shown on "chain.so"

[jfdutcher]

If you go to this URL:   https://blockchain.info/address/1L2i3QJkFShpUomr8g9wX2BXjfe45x4kGS

you see where the Virwox company observes I sent bitcoin to address:  1L2i3QJkFShpUomr8g9wX2BXjfe45x4kGS

They then state that I spent it from there about one-half hour later.

I believe I bought quarkcoin at that time with it (Jan 11, 2014).

How can the address:  1L2i3QJkFShpUomr8g9wX2BXjfe45x4kGS    still seem to show more 'spent' activity going
forward if I used all the coins for quarkcoin on that day ?    I cannot locate those quarks on the quark explorer, it's
true..........but wherever they went ......... I puzzle at how I can keep tracking 'spent' addresses endlessly which
involve much more bitcoin than was involved in my spend just by clicking address links..

[RGBKey]

Once you deposit your Bitcoins into Virwox by sending them to that address, they become a part of Virwox's wallet. This means that they can be combined with other people's transactions, or split up, or sent around however Virwox likes to because that money belongs to them now. As you click on "spent" it takes you to the next transaction or transactions those coins were spent in, possibly other people were withdrawing from Virwox or anything else really.

The point is that once you send someone Bitcoin, it becomes theirs to send on to whoever else they want to. It's like if you pay somebody by giving them a $5 bill, but then they later used that $5 bill, plus some other bills they had to buy something for $20. The next transaction contains more money, but not all of it was originally yours.