THE RUDOLF REPORT

8. EVALUATION OF CHEMICAL ANALYSESTable 21: Test sample preparation and fumigationNr. Material Conditions25/26 Brick from demolished building fromBavaria; only sample 26 was fumigated!16 h fumigation with 0.3 Vol.%,Storage after fumigation for 120days at room temperature. Nosealing with paraffin27 Cement mortar: 1 part sand, 1 part Portland cement,½ part lime. Sample measurements: 55×60×20 mm,100 g (ca. 1.5 g/cm 3 )28 Cement mortar: 1 part sand, 1 part Portland cement,½ part chalk. Sample measurements: 55×60×20 mm,108 g (approx.. 1.6 g/cm 3 )29 Lime mortar: 2 ½ parts sand, 1 part lime. Samplemeasurements: 55×60×20 mm, 94 g (ca. 1.4 g/cm 3 )30 Lime mortar: 2 ½ parts sand, 1 part lime. Samplemeasurements: 52×58×20 mm, 96 g(ca. 1.6 g/cm 3 )addition of 1 gwateraddition of 2 gwatercement mortar sample, the odor was no longer perceptible after aweek, while in the case of the lime mortar sample, it was no longerperceptible after two weeks. Storage of the samples for more than twomonths at room temperature therefore perceptibly reduced the hydrogencyanide content, while the drying of the samples strongly hinderedthe conversion to iron cyanide.The analytical results relating to the brick samples (Table 19, p.254, Sample no. 25 and 26) are surprising for their values, which appearparadoxical: the fumigated sample, in contrast to the unfumigatedsample, exhibited no traces of cyanide. The value of the unfumigatedsample could be exactly reproduced (Table 20). Further analyses of thefumigated brick likewise resulted in no demonstrable cyanide concentrations.These findings prove that cyanide values up to 10 mg per kghave only very limited probative value, since these can be attributed totraces which occur everywhere. 510The interpretation of the analytical results of samples 27 to 30 resultedin the following data:• In total, 30 mg of cyanide were found in the samples during theanalysis. Since 300 mg cyanide were used during this test, 10% of510It is also conceivable that the unfumigated samples were contaminated during preparation foranalysis, perhaps through an improperly cleaned ball mill, in which samples with a high cyanidecontent had previously been crushed. The reason for the good reproducibility may be thatthere is hardly any carbonate in brick, since it acts as a disturbance ion.267