Stained-glass painting—a form of vitreous enamelling—very rarely gives rise to poisoning, as no dust is generated (see vitreous enamelling for use of aerograph in glass-painting).

Paints and Colours.

[33]—Most of the cases have occurred in the manufacture of white-lead paint, although manufacture of chromate of lead and of Brunswick greens (barytes with which Prussian blue and chrome yellows are mixed) account for several. The following table shows the precise occupation of persons affected, the number of cases distributed according to precise occupation, and the proportion of these to the total in 225 cases which were closely examined:

Precise Occupation
of Person affected.		Number
of Cases
in each
Subdivision.		Proportion
of Cases
to Total
(per Cent.).
Mixing and grinding (mainly of white lead)14464·0
Packing (mainly of red lead) 19 8·4
Sieving  2 0·9
Manufacture of chrome yellow 22 9·8
Colour house and filters 16 7·2
Painting and stencilling  6 2·7
Other processes 16 7·0

Knowing the conditions of work, we can confidently assert that the poison must have entered the system in the form of dust in at least 90·0 per cent. of the cases, and in the remainder the possibility of dust having been the cause is not excluded.

In a small factory the cask of white lead is broken and the material scooped out into a pail. Scales are at hand, and when the amount of lead removed weighs half a hundredweight the contents of the pail are discharged either into a cylindrical pug-mill or into the pan of an edge-runner to be mixed with oil. In large factories the dry white lead is generally shovelled directly from the cask down openings or shoots in the floor to the grinding mills below.

Dangers and Prevention.

—Dust arises in unheading the casks from the displacement of air following the scooping or shovelling out of the lead, in filling the pails, and in discharging the lead into the mill. All points should, and can, be adequately protected by locally applied exhaust ventilation at each one of the points enumerated. A telescopic arrangement of the branch duct in connection with the barrel enables dust generated in scooping out to be removed as the contents of the barrel get lower and lower (see [Fig. 15]).

Fig. 15.[A]