=Heading of Yarn dyed with Chromate of Lead.=--Cotton yarn is dyed (10) on a considerable scale with chromate of lead, chiefly for Oriental markets; and it is the orange chrome--that most heavily weighted with lead--which is most in demand there. The orange chrome colour is obtained by dipping hanks of yarn into solution of lime, and then into acetate of lead. The process is repeated a second time, after which the chromate is formed by dipping in bichromate of soda, and finally boiling in lime-water[39]. In production of yellow chrome colour, the yarn is treated only once in a bath of lead acetate. Other colours made are lemon chrome and (by addition of an indigo bath) chrome green. The early processes of dyeing rarely give rise to poisoning, but the strong solution of bichromate of soda readily causes characteristic ulceration of the skin--“chrome holes.” Danger arises from dust in the process of heading or “noddling,” as it is sometimes called, of the dried yarn over posts. The hanks of yarn are tugged and shaken by women as a rule, and in the case of orange chrome very considerable quantities of dust are liberated. We have been told that a hank of this kind of yarn does not commend itself to an Oriental buyer unless, when shaken, dust is visible. The industry was certified as dangerous in 1895, in view of serious illness and death in Glasgow and Manchester, and special rules were made to apply, not only to the heading operations, but also to the winding, reeling, and weaving, of the dyed yarn--processes in which cases of poisoning are very rare. Detailed inquiry was made in 1906 in eleven factories where yarn was dyed on a considerable scale by means of chromate of lead--in eight mainly for export to India, and in three for the home market. Yarn dyed for the home market gives off less dust when headed, as the material undergoes additional washing in water and in dilute acid; and it is also sometimes passed through a sizing of starch, which fixes the chromate of lead to the yarn more securely. Proof of the greater danger from orange chrome is found in the fact that Dupré was able to wash 1 pound of dust (0·29 per cent.) from 345 pounds of heavy orange yarn, and only 1 pound (0·03 per cent.) could be washed from 3,300 pounds of light yellow or green yarn. In none of the factories were the workers engaged solely on the dangerous yellow and orange chrome-dyed yarn. In some the work may last an hour or two every day, in others for an hour or two every day in alternate weeks, or for one week in every three or four weeks, and perhaps in a dozen factories the work may not be done more frequently than half a day a month, or even one in three months.