The next step in the conservation of the diorama taxidermy will be surface cleaning to remove dust, mould spores and the powdery substances that have accumulated on many of the specimens. There is a high likelihood of the presence of arsenic in any 19th Century taxidermy and as discussed in previous posts, it was known to be a pest deterrent employed in the Suffolk Street shop by Richard Glennon.
To determine the potential arsenic content of the diorama specimens, I chose an Osumex heavy metals testing kit which provides quantitative results measured in parts per million (ppm). The test was also relatively inexpensive and easy to administer, both big plusses! Although intended for liquid samples, the Osumex kit below also included very clear directions for making up a test solution from dry ingredients and so this was the method I followed in order to test the powdery substance from the Kestrel pictured above.
A few quick arsenic facts as supplied in the Osumex test kit…..
- Arsenic is the 20th most abundant element in the periodic table and is most commonly found combined with sulphur and iron ores.
- Traces of arsenic are found everywhere in water, soil, food, and the air with higher levels present in areas of sedimentary rock like India, China and South America.
- Studies have determined that levels of arsenic between 50-200 micrograms per litre are enough to cause health concerns.
Arsenic poisoning can result in wide ranging symptoms most commonly including vomiting, abdominal pain, diarrhoea and skin lesions.
So with those very unpleasant symptoms in mind, I gathered appropriate personal protection equipment (PPE) and glassware before beginning the test.
In order to make up a test solution, I first scraped the loose white powdery substance from where it had accumulated around the face, feet and underneath the wings. This dry powder was added to a test tube of de-ionised water, stirred vigorously and then left to sit for 24 hours.
Following the instructions supplied with the kit, I first added reagent 1 (with the red cap) to the test tube along with the test solution and stirred it thoroughly. Next, reagent 2 was added (the clear cap) and this was similarly mixed. The final step was to add the third reagent (blue cap) and immediately put on the test tube cap with indicator strip suspended 20mm above the solution which by this time was fizzing away. For 30 minutes the test tube had to be shaken at 5 minute intervals taking care not to splash the solution onto the indicator stick.
Finally, after much anticipation, the 30 minutes were up and it was time to dunk the indicator strip into water and compare it to the colour strip. The colour change was not as pronounced as I had thought it might be, indicating that arsenic was present in a quantity of somewhere between 0.1 and 0.25 ppm.
Moving forward, it will be extremely important to wear PPE at all times when handling and working with the diorama specimens. The white powder present on the surface of the taxidermy became airborne with very little encouragement and likely contains mould spores as well as traces of arsenic and other chemical used in the preserving of the skins.