Q: How long can a serial cable be?

[itsme <quantum@telis.org>]

I want to connect my Apple II to my PC with a serial cable.  

I have my Apple II in a room that is about 54 ft from my PC.

Q#1     How long can a serial cable be and the computers still be able to 
read the serial data?

I already have a 50 ft serial cable.  I need 4 more feet!

Q#2    Will this extra          'serial cable(50ft)to serial cable(4ft.)' 
connection                      
cause any problems such as data loss or scrambling?

I want to find out before I go get the other cable.

Thanks.