The Carpenter Eozoon Collection, linking curation and conservation

Portrait of William Benjamin Carpenter (1813-1885). © The Trustees of the Natural History Museum, London, CC-BY.

The Natural History Museum houses the Carpenter Eozoon Collection. Collection that has been the object of a long controversy between evolutionists and “old-school” naturalists. The significance of Eozoon hinged on its Precambrian age, with some scientists regarding it as a foraminiferan (single celled shelly marine organisms) and hence the oldest evidence for life on earth, while others considered it to have an inorganic origin. Even Charles Darwin cited Eozoon in his work On the Origin of Species of 1866, accepting its identity as an ancient fossil. This Eozoon is now universally recognised as being inorganic in origin.

William Benjamin Carpenter (1813-1885) was an expert in the study of Foraminifera and this made him the chosen person to confirm that the Canadian specimens were indeed of foraminiferal origin. If this was correct, these specimens would be a cornerstone for the study of early life, contributing significantly to an understanding of the origin of life on earth.

Their microscopic structure initially gave no evidence of organic structure. But, in 1864, similar specimens were found in the Grenville Limestone near Ottawa. Thin sections were prepared and sent to Sir John William Dawson (1820-1899) who identified them as foraminifera. Thin sections were also sent to Carpenter who supported Dawson’s opinion. Subsequently, Carpenter accumulated a huge collection of rock samples from around the world containing Eozoon from which more than 1000 slides were made and presented by his son, the Reverend Joseph Estlin Carpenter (1844-1927), to the British Museum (Natural History) in 1892, almost seven years after the death of his father.

Since its deposition, the Carpenter Eozoon Collection remained untouched until 2014 when it was decided that the long overdue conservation and curation of this controversial and important historical material should be undertaken.

Specimen of the Carpenter Collection. © The Trustees of the Natural History Museum, London, CC-BY.

The unusually thick layer of dust on the specimens inside the cabinets attracted our attention and led us to search for other parts of the Carpenter Eozoon collection. This collection was found to be distributed in different buildings and contained in several cabinets. Part belonged to the Mineralogy Section and part to the Palaeontology Section, reflecting the early controversy over the inorganic vs organic origin of Eozoon. The Eozoon Collection is mostly distributed in the specimen drawers of the main collections, except for two small wooden cabinets that are kept inside of one of the larger collection cabinets in the Palaeontology Building. The latter material was the focus of a study combining curation and conservation work. The material contained in the wooden cabinets contains cavity slides, thin sections and hand samples. One of these small wooden cabinets contained specimens that were covered by a very thick layer.

During the cleaning process it became apparent that the dust covering the specimens inside one of the small wooden cabinets was different from the dust accumulation in the other cabinet, which was very dark in colour. This suggested that these specimens could have been stored in a different environment from the others and had a separate history. The dark coloured dust could have come from a domestic fire used for heating, an accidental conflagration, or from the smoking of tobacco as it has been seen on other specimens.

Wooden slide cabinet that contained the dusty Eozoon specimens. © The Trustees of the Natural History Museum, London, CC-BY

We collected several samples of dust from the outer part of one of the dirtiest specimens for SEM-EDX (scanning electron microscopy with energy dispersive X-ray spectroscopy) analysis. At the same time, we investigated the history of the Carpenter Collection both before and after it was transferred to the NHM UK. We tried to match the results of the chemical analyses and the historical record, in order to shed light on the source of the unusually high density of dust. Chemical analysis of the dust revealed high contents of Ca and S, interpreted as indicating the presence of gypsum, most probably of anthropogenic origin (plaster?).

View of a tray with fragments of disaggregated specimens of Eozoon. © The Trustees of the Natural History Museum, London, CC-BY

The Eozoon specimens were housed in William Carpenter’s private residence from his retirement in 1879 until his death in 1885. It is during this time when Carpenter devoted most of his time to his Eozoon Collection, working on a monograph, accumulating further material and making drawings to support his interpretation of this “fossil” as a foraminiferan.

One possibility worth considering for the origin of the dust covering the specimens that it represents is soot and other debris resulting from the accidental house fire that led to the death of Carpenter in 1885. No details of the extent of the fire are known but it would have at least burned in the room where Carpenter kept the vapour bath for treating his rheumatism if not elsewhere in the house.

Lessons learned: The collections should be inspected and recorded their state upon arrival at the Museums, in order to take any remedial work necessary before their storage, avoid deterioration.

To know about this: Sendino M.C., Cuadros J, Allington-Jones L, Barnbrook JA (2015) Chemical Analysis of the Dust on a Historically Important Collection: The W. B. Carpenter Eozoon Collection at the Natural History Museum, London. Collections: A Journal for Museum and Archives Professionals, 11 (4): 291 – 304.

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