sorry for posting in such an old topic but I think I got some information\question to add.
I bought sodium thiosulfate and tried the Improved mixture I.
In powder form it didn't light, I used Ca(OH)2 to replace CaO. when I wetted it a little to make cut stars it started foaming after some minutes and a smell of sulfur (I guess H2S) was coming out of it.
I will wait till it will be dry and try to light it again, but I'm quite sure it won't be very lightable.