I'm probably a bit late in sending this but here goes.
F.Y.I.
This is quoted straight from the label of my 
Mallinckrodt.Parlodion (strips)(A Purified Pyroxylin)

"Mallinckrodt Parlodion is a highly purified form of non-explosive
cellulose nitrate,especially prepared for embedding tissues for section
cutting,and preparing semipermeable membranes.
Mallinckrodt Parlodion keeps perfectly when dry,and dissolves rapidly in
ether-alcohol mixture.It burns rapidly,but there is no danger of
explosion."
This product is from Mallinckrodt Chemical Works,St Louis,MO.63160.

Cheers,Lorraine.
Histo/Anatomy/Uni.of Akld.NZ