I believe that it is soap for removing blood stains from a toga.....
got some new info...yes ,it is manufactured in greece,some bizarre "powdered" form of shaving soap !...mix with water and whip with brush...not too good from what I hear,and now possibly discontinued,but still on sale at global ebay..
It might be worth a try anyway. Shaving soap powders used to be fairly popular, or at least widely marketed.