Prussian blue penetration depth.

Many years ago a few article drafts appeared on the late Harry Mazal's website mazal.org. One of them was entitled "Techincal requirements for a gas chamber and some observations on Prussian blue".

It turned out to be a draft of the article quoted by Dr. Richard Green in his devastating rebuttal of the fraudulent Holocaust denier Germar Rudolf. Apparently it was initially to be a part of the collective report responding to Rudolf, though later it was decided that only Dr. Green and Prof. Jan van Pelt would officially respond.

The drafts disappeared from the site some time later, and Mr. Mazal died in 2011. The paper was left unpublished, and it is highly unlikely that it will ever be published. Therefore I decided to post an excerpt from this article that concerns one point about the formation of Prussian blue with several valuable photos.

The excerpt follows. There has been some minimal editing of the references (like picture numbers).

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What can be proven, to the embarrassment of deniers and pseudo-scientists is that Prussian Blue only stains the surface of mortar, plaster and brickwork. With the permission of the authorities of the Auschwitz Birkenau State Museum, and under the watchful eye of one of its official guides, a number of very small samples of brickwork, mortar and plaster were carefully removed for further analysis. Viewed under a simple loupe, it could be seen that Prussian Blue hardly penetrated the surface of these samples.

The following samples were viewed using a simple Intel Model QX3 Computer Microscope. The images were exported into Photoshop 6.0, labeled, sized, and converted to HTML without further modification.

Illus.1: Fragment of wall "e" in BIa bath and delousing building with strong Prussian Blue staining (x10).

Illus. 2: Cross-section of sample shown in Illus. 1 showing minimal penetration of Prussian Blue into the body (x10).

Illus. 3: Cross-section of sample shown in Illus. 1 showing minimal penetration of Prussian Blue into the body (x60).

Illus. 4: Cross-section of sample shown in Illus. 1, tilted to show Prussian Blue stain on surface.

Illus. 5: Brick sample from exterior wall "E" of bath and delousing building in BIa showing heavy Prussian Blue staining (x10).

Illus. 6: Cross-section of brick sample shown in Illus. 17 showing minimal penetration of Prussian Blue stain (x10).

Illus. 7: Brick sample from exterior wall "E" of bath and delousing building in BIa showing heavy Prussian Blue staining (x10).

Illus. 8 Cross-section of brick sample shown in Illus. 7 showing minimal penetration of Prussian Blue stain (x10).

As may be observed in the eight photographs above, penetration of Prussian Blue into either the wall material inside of the building, or the bricks on the exterior, is minimal, corroborating previous reports. It is possible that very porous materials such as plaster might permit a slightly greater penetration of the stain, but not to the degree claimed, without proof, by Holocaust deniers.

There is an as-yet unsolved mystery of how Prussian Blue made its way through apparently solid brick walls leaving its tell-tale blue stains on the exterior of both bath and delousing chambers in BIa and BIb in Birkenau. An answer might be found by looking carefully at Illus. 9.

Illus. 9: Brickwork and Mortar on Exterior wall "E" of the bath and delousing building in BIb.

This close-up picture shows strong Prussian Blue staining on both mortar and brickwork. Two other facts are revealed: (1) The stain scarcely penetrates the mortar. The broken section reveals pristine, unstained material proving that Prussian Blue does not penetrate solids to any great degree; and (2) the stains on the bricks appear like a semi-transparent wash, suggesting that the bricks are not subject (as was shown in the illustrations above) to any great penetration by the pigment.

A third, much more subjective, observation regards the patterns that the stain has left on the brickwork and mortar. The stain gives the appearance of having come through cracks in the mortar as a liquid and flowed down the surface of some bricks and part of the mortar. The stain is indeed stronger at the points where the mortar meets the bricks. If Prussian Blue is insoluble and practically inmiscible in water, whatever came through those walls must have had cyanide in some soluble form together with iron salts sufficient to react in order to form Prussian Blue. Furthermore, it could not be hydrogen cyanide in gaseous form as this would have dissipated immediately upon being released to the atmosphere.