While it is an unusual usage, you can say someone is ‘in dependence’, but this suggests that he is in a psychological state of dependancy, not that he is dependant on something like e.g. a wifi connection.

‘in-’ in the word ‘independence’ is a prefix indicating ‘without’. If one has independence, it means one is not dependant.

In English, we sometimes say that someone is "in denial"; what we are actually saying is that the person in in (a state of) denial. Adam, similarly, may be in (a state of) dependence on his wireless connection. But, (what is) more important, the sentence as it is now structured fails the most basic requirement for written communication: it muddles, rather than clarifies, your message.

All right then, what about "flammable" and "inflammable"?

There are two different Latin prefixes that mean different things but, as it happens, both take the form "in-". One of them indicates negation and is cognate to the Germanic prefix "un-" or the Greek prefix "a-"; examples: infidelis = not faithful, invisibilis = not visible. The other one indicates movement toward and is related to the preposition "in"; examples: inflammare = to set something on fire, influere = to flow into.

All right then, what about "flammable" and "inflammable"?

They both mean the same thing: that something is burnable. American usage is ‘flammable’ and British usage is ‘inflammable’. In this case the prefix ‘in-’ means into or towards.

Yes, the prefix ‘in-’ has two different meanings.

Such a strange language we speak... thanks everyone. Can you recommend a good read on these subjects?

I highly recommend http://www.amazon.com/Joy-Lex-Amazing-Amusing-Words/dp/1861053991

Strunk and White's lightly contemptuous take on "flammable" is quoted here.

Enjoyed reading all that. Thanks.