Arsenical

containing or relating to .
any of a group of pesticides, drugs, or other compounds containing .
historical examples

-rs-nical soaps, &c.—-rs-nic is used in preserving the skins of animals.
poisons: their effects and detection alexander wynter blyth

-rs-nical compounds have supplanted practically all other substances used to combat external biting insects.
apple growing m. c. burritt

some taxidermists prefer to use in place of the paste some form of -rs-nical soap.
home taxidermy for pleasure and profit albert b. farnham

iron and -rs-nical pyrites are also very common attendants, and are both confounded under the name of mundic.
a guide to the mount’s bay and the land’s end john ayrton paris

a fresh section of it shows it to be -rs-nical iron pyrites, each piece weighing four or five ounces.
the mound builders george bryce

the -rs-nical vapours being conducted into this p-ssage, adhere both to the sides thereof and to the joists that lye across it.
elements of the theory and practice of chymistry, 5th ed. pierre joseph macquer

this is owing to some particles of inflammable matter, from which -rs-nical minerals are seldom quite free.
elements of the theory and practice of chymistry, 5th ed. pierre joseph macquer

adjective
of or containing -rs-nic
noun
a drug or insecticide containing -rs-nic

-rs-nical ar·sen·i·cal (är-sěn’ĭ-kəl)
n.
an agent containing -rs-nic. adj.
of, relating to, or containing -rs-nic.