How Can I sent to serial port a float?

Hi!
In my project i sent to serial port a int :

unsigned int X;
        putchar(X);
        putcahr(X>>8);

and everything to work OK!!

but if i want change my data type and use float, i cant do

putchar(X>>8)

.
I trying it:

float X _at_ xxxxx;

and with a function i read all adress of my data but it no work.

Any idea to do it??
thanks