Why '8'?  It's already on 'the Chart' (Oxygen).  I would have designated HU as '0' - to represent the numinous ethereality of heart-soul.  But I bet Dow was anticipatingly sensitive to a criticism that designating HU as '0' would indicate that they considered HU to be 'nothing', 'worthless', 'zilch'.   Hence, in the interest of good PR, they have here propagated a snippet of bad science.  Just as in the interest of profit, they have in the past, prostituted good science.  Still, a rather captivating and atypical ninety seconds of elementalism here.