Hi EmilyB,
I was also dismayed by the term washing soda, but after having read numerous post, it the chemical composition that is omportant and not the name.
See thread from RC where RHF recommends the use use of Washing Soda. I did a search in the Chemistry Form using "Washing Soda" as the keyword.
web page
What bothers me the most is the scent. Is it supposed to smell like that. The box has no indication of ingrediants except to say that it has no phosphates.