=Chronic Colic.=--The acute form of lead colic frequently passes on to a chronic condition; the attacks become much less intense, and may at times only amount to general discomfort in the abdomen, but the symptoms may last for several weeks, and even months, with no abdominal discomfort for a period of a week or ten days, then recurrence of pain, gradually increasing until it has attained a considerable degree of intensity, and then passing away, only to reappear in two or three days’ time. In such cases of prolonged colic after an interval of two or three weeks, small doses of strychnine or tincture of nux vomica will determine the onset of an attack of colic, showing that the intestinal muscular tissue remains in a state of hypersensibility long after the attack appears to have passed away. A particular form of colic of long duration with exacerbations and remissions has been known for many years in the French navy, called “seamen’s colic.” Before this time outbreaks had occurred in various parts of the world, and John Hunter[9] described a form of _dry bellyache_ occasioned by drinking certain West Indian wines, the wines in question having been stored in contact with lead--in fact, the vigorous Saxon of John Hunter peculiarly describes this chronic form of lead colic. Although the prodromal stages of malaise, lassitude, loss of appetite, nausea, etc., generally precede both the acute and the chronic forms, colic often commences suddenly. Men may be examined in the factory in the morning, when the ordinary routine examination has elicited no symptoms, and yet cases of acute colic have occurred later in the same day in the very men examined. The chief points associated with lead colic are-- 1. The intermittent character. 2. The relation of the colic mainly to the lower part of the abdomen. 3. The slowing of the pulse. 4. The relief afforded by firm pressure on the abdomen. To which may be added the action of amyl nitrite and other drugs of a similar physiological action.