dates when something happens

[upthera44.livejournal.com]

Over time I've somehow forgotten how to express when something happens with dates. 

I know there are two ways -- в + accusative case  OR  genitive case without a preposition: 

во второе июля...

втогоро июля...

When is each used? 
Thanks!

Железнодорожная вода

[olydiagron.livejournal.com]

What is the symbolic meaning of "railway water"? I've heard it in lyrics and read it in essays... Help!

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