In comparison with chemical workers they have, it is said, relatively the lowest morbidity. Although in this industrial occupation no special factors are at work which injure in general the health of the workers, there is a characteristic effect, without doubt due to the occupation—namely, disease of the respiratory organs. Leymann’s figures are sufficiently large to show that the number of cases of diseases of the respiratory organs is decidedly greater in the sulphuric acid industry than among other chemical workers. He attributes this to the irritating and corrosive effect of sulphur dioxide and sulphuric acid vapour on the mucous membrane of the respiratory tract, as inhalation of these gases can never be quite avoided, because the draught in the furnace and chamber system varies, and the working is not always uniform. Strongly irritating vapours escape again in making a high percentage acid in platinum vessels, which in consequence are difficult to keep air-tight. Of greater importance than these injurious effects from frequent inhalation of small quantities of acid vapours, or employment in workrooms in which the air is slightly charged with acid, is the accidental sudden inhalation of large quantities of acid gases, which may arise in the manufacture, especially by careless attendance. Formerly this was common in charging the roasting furnaces when the draught in the furnace, on addition of the pyrites, was not strengthened at the same time. This can be easily avoided by artificial regulation of the draught. Accidents through inhalation of acid gases occur further when entering the lead chambers or acid tanks, and in emptying the towers. Heinzerling relates several cases taken from factory inspectors’ reports. Thus, in a sulphuric acid factory the deposit (lead oxysulphate) which had collected on the floor of a chamber was being removed: to effect this the lead chambers were opened at the side. Two of the workers, who had probably been exposed too long to the acid vapours evolved in stirring up the deposit, died a short time after they had finished the work. A similar fatality occurred in cleaning out a nitro-sulphuric acid tank, the required neutralisation of the acid by lime before entering having been omitted. Of the two workers who entered, one died the next day; the other remained unaffected. The deceased had, as the post mortem showed, already suffered previously from pleurisy. A fatality from breathing nitrous fumes is described fully in the report of the Union of Chemical Industry for the year 1905. The worker was engaged with two others in fixing a fan to a lead chamber; the workers omitted to wait for the arrival of the foreman who was to have supervised the operation. Although the men used moist sponges as respirators, one of them inhaled nitrous fumes escaping from the chamber in such quantity that he died the following day.