A kind of glass wool is produced by drawing out to a capillary thread two glass rods of different degrees of hardness.
Inside the inner skin there was a layer of glass wool for heat insulation.
Inside the glass wool was a layer of material serving exactly the function of the coating of a bulletproof gasoline tank.
glass wool serves to hold the calcium chloride and iodine in place.
The flask was then allowed to cool, the entering air being filtered through a plug of glass wool or asbestos.