Urist Da Vinci's delete blood script from http://www.bay12forums.com/smf/index.php?topic=91166.msg4246062#msg4246062

blooddel.lua

local my_entity=df.historical_entity.find(df.global.ui.civ_id)
local sText=" "
local k=0
local v=1

for x,y in pairs(df.global.world.entities.all) do
my_entity=y
k=0
	while k < #my_entity.resources.misc_mat.extracts.mat_index do
		v=my_entity.resources.misc_mat.extracts.mat_type[k]
		sText=dfhack.matinfo.decode(v,my_entity.resources.misc_mat.extracts.mat_index[k])
		if (sText==nil) then
			--LIQUID barrels
			my_entity.resources.misc_mat.extracts.mat_type:erase(k)
			my_entity.resources.misc_mat.extracts.mat_index:erase(k)
			k=k-1
		else
			if(sText.material.id=="BLOOD") then
				my_entity.resources.misc_mat.extracts.mat_type:erase(k)
				my_entity.resources.misc_mat.extracts.mat_index:erase(k)
				k=k-1
			end
			if(sText.material.id=="ICHOR") then
				my_entity.resources.misc_mat.extracts.mat_type:erase(k)
				my_entity.resources.misc_mat.extracts.mat_index:erase(k)
				k=k-1
			end
			if(sText.material.id=="GOO") then
				my_entity.resources.misc_mat.extracts.mat_type:erase(k)
				my_entity.resources.misc_mat.extracts.mat_index:erase(k)
				k=k-1
			end
			--VENOM
			--POISON
			--FLUID
			--MILK
			--EXTRACT
			
		end
		k=k+1
	end
end