(Updated, February 2018)This view may show the manufacture or refinement of combustibles, possibly of saltpetre (potassium nitrate [KNO3] for fuses) by being heated and then filtered. In the centre the mixture is apparently either being filtered out through cloth filters stretched on the large frame to collect the chemically impregnated solid residue, or just being strained for drying and grinding, into glazed earthenware containers: the matter requires more specialist research to explain the details. A row of copper vessels on the right appear to be in graduated sizes for measuring ingredients. The barrel at right may contain saltpetre. The Royal Laboratory at Woolwich was constructed in 1696 for the purpose of manufacturing munitions and became centre of a larger site, formally renamed the Royal Arsenal in 1805. This drawing is one of 11 of which the numbers are non-sequential owing to the different boxes in which they are stored (by mount size): PAG9664, PAH4071-72, PAI0744-46, PAI7701-03, PAJ2303 and PAJ2312. Four (including this one) were reproduced as a double-page spread in the 'Illustrated London News' of 1 January 1916, pp.14-15, as having recently appeared at auction by Messrs Hodgsons' and been bought by the ILN for that purpose. This makes it likely that they were later given to the NMM by Sir Bruce Ingram, managing proprietor and editor of the ILN and an early supporter of the Museum. They have been attributed to Gamaliel Massiot, an obscure artist of probably Huguenot French ancestry who was drawing master at the Royal Military Academy at Woolwich from 1744 to 1768, after which he continued in a secondary position under Paul Sandby to shortly before his death early in 1782 (see further notes to PAI0746).