On the action of nitric and nitrous acids on the sulphocyanides / by Edmund W. Davy.

  • Davy, Edmund William, 1826-
Date:
1865
Catalogue details

Licence: Public Domain Mark

Credit: On the action of nitric and nitrous acids on the sulphocyanides / by Edmund W. Davy. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    From the Philosophical Magazine for September 1865. EDMUND W. DAVY, A.B., M.B., M.R.I.A., PROFESSOR OF AGRICULTURAL CHEMISTRY TO THE ROYAL DUBLIN SOCIETY, ETC. SOME time since, having had occasion to test a sample of carbonate of potash (which I believed to be very pure), to ascertain if it was perfectly free from iron, and suitable for the purpose required, I was surprised, on dissolving a little of it in water and supersaturating the solution with some carefully purified nitric acid, to find that the mixture, on the addition of a few drops of a solution of sulphocyanide of potassium, became of a reddish colour, indicating apparently the existence of a small quantity of iron in the mixture. Conceiving that the coloration observed was caused by the presence of that metal, I proceeded to ascertain whether it existed in the acid or in the carbonate. A few experiments showed me that the effect was due to the acid; for I found, on testing a diluted portion of it with sulphocyanide of potassium, that it soon acquired the same reddish tint; whereas some of the carbonate of potash, after supersaturation with pure hydrochloric acid, did not acquire the reddish tinge on the addition of the sulphocyanide, or give the slightest indi- cation of iron when tested with either the ferrocyanide or ferrid- cyanide of potassium, clearly proving that the effect observed was alone attributable to the acid. This I thought was rather singular, as the nitric acid I employed was very carefully pre- pared by myself, and I believed that it was chemically pure. A considerable portion, however, of this acid being evaporated