3.8 Quicksilver, in bottles?
During the excavation, small beads of mercury were occasionally found, rolling in hollows in the sand, in the grooves of wrought-iron or adhering to brass pins. A few drops were collected (fig. 36), most of them together with pins. Although there was some apprehension with regard to the presence and handling of mercury (and lead), this did not lead to a precautionary regime in the excavation. Protective clothing and dive suits were evidently worn, and common sense in handling was relied upon. Although only small amounts were registered, these were found so dispersed that they must represent a considerable shipment.
Mercury or quicksilver is occasionally found in historical wrecks. It is relatively rare and expensive. Mined at various places in Europe, such as France, Austria, Hungary, Poland, Spain and the Balkan peninsula, it was used in thermometers and barometers, in making mirrors and felt hats. Large amounts were needed in metallurgical processes, notably the extraction of silver. Although it was traded over long distances, transport of the liquid and very heavy metal (density of 13546 kg/m3) was problematic.
In an 18th-century Spanish wreck off the Dominican Republic, a large consignment of mercury has been discovered in small casks packed in cases (Peterson 1979). Evidently, various containers were tried, as is reflected in successive directives of the Dutch East India Company VOC (Green 1977). In the 17th century it was shipped to Asia, probably to be used for the gilding of objects (Sténuit 1977, 441-443). It was also taken on board as part of the ship’s pharmacy (Gawronski 1996, 212). In archaeological literature, Bellarmine jugs are referred to as the most common containers for mercury in the Aanloop Molengat period (Green 1977, 481). No sherds of such jugs were found. The only possible container elements in the assemblage are lead screw caps (fig. 37). Twenty-three caps were found, consisting of a lower part, which was attached to a glass bottle, and an upper part, which could be screwed onto the lower part. The caps have a diameter of 1.8 to 2.3 cm and a height of 2.0 to 2.4 cm. XRF measurements revealed mercury inside these caps, at the bottleneck (van Os 2011 HyperlinkVan Os). This mercury may have attached itself to the caps in the same way as it did to pins, but it would be more logical to assume that the mercury was stored and transported in glass bottles with lead screw caps. The same suggestion is made in relation to bottle caps and neck reinforcements of similar type in the assemblage from the Lastdrager that wrecked in 1653 (Sténuit 1977, 440). It is notable that one of the 1636 VOC regulations recommends the use of square bottles in a case (Green 1977, 481). Although some glass was found, it is too little for reconstructing bottle form and size. Square capped storage bottles (kelderflessen) are known in sizes varying from 235 ml to 1.8 l or more (Henkes 1994, 236-244). If the caps sat on bottles of 1.2 litres, 23 bottles would account for approximately 375 kg of mercury. It is likely, however, that the 23 caps represent only a fraction of the total number of bottles.