Report on three samples of Violet Powder received from Mr. W. H. Power, April 4, 1878.
Reading edition
All the powders were of a very pale yellowish colour, and rather more gritty to the touch than ordinary violet powder; they were also appreciably heavier, bulk for bulk. Taking the weight of a given bulk of ordinary violet powder as 1, the same bulk of these powders would weigh about 1.25. Under the microscope they are shown to consist of potatoe starch mixed with a very considerable proportion of crystalline matter, among which regular octahedra (arsenious acid) can be distinguished. On burning they evolve a very powerful arsenical odour.
Chemical analysis showed them to consist in 100 parts of
A B C
Starch with traces of other organic matter 37.58 34.56 36.76
Arsenious acid (white arsenic) 50.34 51.40 48.94
Oxide of lead [6] 1.07 1.16 0.83
Other mineral matters chiefly carbonate of magnesia 11.01 12.88 13.47
100.00 100.00 100.00
A. Dupré.
Westminster Hospital, April 13, 1878.