Estimations[4] of the amount of lead in air samples collected in lead smelting works have been made. Thus in a cubic metre of air immediately over the slag run from 0·0029 to 0·0056 g. of lead were found, so that a worker in a ten-hour day would inhale from 0·013 to 0·025 g. of lead. In a cubic metre of air immediately above the Parkes’ melting-pot from 0·0056 to 0·0090 g. were found, so that a worker would inhale daily from 0·0252 to 0·0405 g. if he kept constantly close to the pot. On the handles of a de-silveriser 0·112 g. were found. In Hungarian lead-smelting works the water in which the hands had been washed was found to contain 1·27 g. of lead per litre. The hands of litharge grinders and sifters showed the highest amounts. Work carried on in lead-smelting works may be divided into five classes according to risk. Those most exposed to risk are the smelters at lead hearths and reverberatory furnaces, persons employed at the lead and slag runs, flue cleaners, and in crushing and packing flake litharge. Next come those employed at the refining furnaces, those breaking up the roasted ore, blast furnace workers, and those employed at the cupellation process. Attended with danger also is the removal of lead ashes and distillation of the zinc crust. Less dangerous are transport of material, crushing and mixing the ore, refining the work-lead and zinc crust, and work at the Pattinson and Parkes’ processes. In zinc smelting risk of lead poisoning is great, no matter which process is in question, because of the high proportion of lead in the ore and work-zinc. Swedish blende contains as much as 9 per cent. of lead, and Upper Silesian 2½ per cent. or less. There is risk in calcination, but it is much less than in the distillation process.[5] There are no quite satisfactory statistics as to the number of cases of lead poisoning in smelting works. Nevertheless, a number of recent publications give valuable data for certain smelting works in Germany, Austria, and Hungary. From details[6] of lead poisoning at Tarnowitz it would appear that the conditions have materially improved since 1884, the cases having declined from 32·7 per 100 employed in 1884 to 6·2 in 1894 and 1895. The following figures show the proportion affected in the different processes in the years 1901 and 1902: Process. Year. No. Employed. Cases. Per Cent.