Note 400 — PHARMACOLOGIA. (continued 2)

It will probably afford a satisfactory explanation of the circumstance mentioned by Dr. Percival, that the workmen who solder silver filligree with an arsenical alloy, are never affected by the fumes. Dr. Percival does not appear to have been in the least aware of the probable reason of this fact; he says, “This solder is melted by the flame of a lamp directed by a blow-pipe; the greatest part of the arsenic is evaporated by the blast and flame, and some part also of the rest of the solder, and yet the men appear to enjoy as good health, and to live as long as other artists! Amongst other examples of the truth of this observation, I lately saw in the manufactory at the Soho at Birmingham, a man of more than fifty years of age, who had soldered silver filligree for thirty-five years, and had regularly, during that period, passed from eight to ten hours daily in his occupation, and yet he was fat, strong, active, cheerful, and of a complexion by no means sickly; neither he nor his brother artists use any means to counteract the effect of their trade.” Dr. Rotheram, in a letter to Dr. Percival, comments upon this fact, and says, “how far the fluxes used in soldering the filligree may fix the parts of the arsenic, or from what cause these workmen might escape, I dare not say, but I should notwithstanding strongly suspect the fumes of this very volatile and caustic mineral to be very prejudicial.”—I have shewn above that arsenious acid is readily decomposed when heated in contact with an oxidable metal, and I apprehend that this fact will explain the reason why the fumes of the alloy in question are disarmed of their virulence.