[515]. The only probable source of such impregnation is pyritic sulphur, which is frequently used abroad, and has of late been occasionally employed in this country, for making sulphuric acid. As pyrites commonly contains arsenic, the acid becomes adulterated with oxide of arsenic, and may communicate the same impregnation to various other reagents which are prepared by means of sulphuric acid. The oxide may easily be detected in that acid by a stream of hydrosulphuric acid gas, after moderate dilution with water; for pure acid is rendered milky; but an arsenical acid yields a yellow precipitate of sulphuret of arsenic.
[516]. Journal de Chim. Méd. viii. 449.
[517]. Reinsch, in Repertorium für die Pharmacie, lvi. 183.
[518]. This has been occasionally observed by Chevallier [Journal de Chim. Méd. 1840, 434], and once by M. Roturier [Ibidem, 627]. The former met with a medico-legal case where from this circumstance an erroneous opinion was at first formed in favour of poisoning.
[519]. London Med. Chirurgical Transactions, iii. 342.
[520]. See a paper by myself in Edin. Med. and Surg. Journal, xxii. 60, where the fallacies to which the liquid tests are liable are investigated at great length.
[521]. Horn’s Archiv für Medizinische Erfahrung, 1827, i. 230.
[522]. Edin. Med. and Surg. Journal, xxii. 74.
[523]. Edinburgh Med. and Surg. Journal, July, 1824.
[524]. Edinburgh New Philosophical Journal, 1836, xxi. 229.