The "glass capacitors" that look like diodes look that way because they ARE
diodes. It turns out that one of the cheapest and best ways to make 0.1uF capacitors is
to make two diodes in the same case, in series with opposite polarities (it never conducts
because one of the diodes is always back biased). The back-biased junction forms the
capacitor, and it has very good characteristics for bypass (decoupling).
As for the 104 notation, this is 10**4 (ten to the 4th power). Thats 10,000 pF = 0.1 uF.
50V is the voltage rating.
Barry Watzman