the continued use of diachylon plaster during eleven weeks for dressing an extensive ulcer.[1] Such accidents are exceedingly rare, and some auxiliary cause must have favoured the operation of the poison in the cases now noticed; for every one knows that free use is made of lead unguents and lotions, yet we seldom hear of any bad consequences.—These cases, however, will probably remove the doubts which some entertain of the possibility of lead colic being induced by the application of the compounds of lead to the sound skin in those trades which compel the workmen to be constantly handling them. At the same time it must be admitted, that in all these trades there exists a more obvious and ready channel for the introduction of the poison; because the workmen are either exposed to breathe its fumes, or are apt to transfer its particles from the fingers into the stomach with their food.—Of all exposures none is more rapid and certain than breathing the vapours or dust of the preparations of lead. But for that very reason workmen who are so exposed seldom suffer; because the greatness of the risk has led to the discovery of means to avert it, and the openness of the danger renders it easy for the workmen to apply them. Tanquerel mentions a singular case of a woman who was attacked in consequence of the fine dust of white lead ascending through chinks in the floor from a room below, where a perfumer was in the practice of grinding and sifting that substance.[2]—It may be added that Dr. Otto of Copenhagen has published an extraordinary instance of fatal lead-colic, originating in the habitual use of Macuba snuff adulterated with twenty per cent. of red lead.[3]
To these observations on the various ways in which lead insidiously enters the system a few remarks may be added on the trades which expose workmen to its influence. The most accurate information on this subject is contained in the work of Mérat.
He places foremost in the list miners of lead. In this country miners are now rarely affected, because the frequency of colica pictonum among them formerly led their masters to study the subject, and to employ proper precautions for removing the danger. It has been stated by Dr. Percival, and is generally thought, that the whole workmen in lead mines are apt to be attacked with the colic,—those who dig the sulphuret as well as those who roast the ore.[4] If this idea were correct, it would be in contradiction with the general principle in toxicology, that the metals are not poisonous unless oxidated. But the opinion is in all probability founded on error; for, according to information communicated to me by Mr. Braid, and confirmed since by personal investigation, the workmen at Leadhills who dig and pulverize the ore, although liable to various diseases connected with their profession, and particularly to pectoral complaints, never have lead colic till they also work at the smelting furnaces.
