It doesn't work. There is no predictor of the babies sex chemically. The only way to know is to wait til he/she is old enough and get an ultrasound. If you suspect you may be pregnant, then you shouldn't be playing with drano or other cleaning chemicals.
I always say, if you are carrying all front ways you will have a boy, if you carry all around and get quite weighty around your hips, then you will have a girl!
Then there is that magpie saying, if you see
1 for sorrow
2 for joy
3 for a girl
4 for a boy