On the other hand, the process of soldering is so analogous to that of tinning that such poisoning as occurs is probably due to inhalation by susceptible persons of lead chloride fumes. And this is borne out by the results of analysis in the Government laboratory of a sample of deposit collected from a duct where exhaust ventilation had been applied to take away the fumes.
The material was a black mass, obviously containing a large proportion of carbon.
On completely extracting with water, the solution was found to show an acidity equal to 0·20 per cent. of hydrochloric acid calculated on the original sample, and in this solution the following metallic substances were present—viz.:
| Percentage on Original Substance. | |
|---|---|
| Zinc, calculated as zinc chloride | 19·53 |
| Copper, calculated as copper chloride | 1·77 |
| Lead, calculated as lead chloride | 0·19 |
Tin and arsenic were both absent, and the chlorine present closely corresponded with the proportion of chloride shown above.
The portion of the substance which was insoluble in water was found to contain the following metallic substances:
| Percentage on Original Substance. | |
|---|---|
| Tin, calculated as tin oxide | 6·09 |
| Lead, calculated as lead oxide | 1·33 |
| Copper, calculated as copper oxide | 0·57 |
| Zinc, calculated as zinc oxide | 0·20 |
This portion of the sample was also free from arsenic.
We believe that where soldering is done by several persons in a workroom, inhalation of the fumes is prejudicial to health, and that the usual methods of localized ventilation are desirable. Where this has been done the result has been in every way satisfactory.
In lead burning the heat from the blowpipe flame is sufficient, if kept long enough in contact with the lead sheet, to cause volatilization of the metal, and, as the worker’s face must necessarily be close to the flame, inhalation of fume is inevitable. Such work, however, has often, unfortunately, to be carried on in confined spaces where exhaust ventilation cannot be applied.