PURSER, an officer aboard a man of war, who receives her victuals from the victualler, sees that it be well stowed, and keeps an account of what he every day delivered to the steward. He also keeps a list of the ship's company, and sets down exactly the day of each man's ad mission, in order to regulate the quantity of provisions to be delivered out, and that the paymaster or treasurer of the navy may issue out the disbursements, and pay off the men, according to his book.
PUS, in medicine. What is called healthy pus is about the consistence of cream, and of a yellowish-white colour, an insipid taste, and when it is cold, with out smell. It produces no change on vegetable blues. When pus is exposed to a moderate heat, it dries and assumes the appearance of horn. By distillation it gives out water in considerable propott. tion, ammonia and some gaseous sub stance, and an empyreumatic oil ; a shin ing cooly matter remains behind, the ashes of which, after being burnt, afford ed some traces of iron. The following tests have been given to distinguish pus from mucus, which is of considerable importance in cases where the formation of pus is suspected in the lungs. 1. Pus
is in sulphuric acid, and precipi tated by water ; mucus swims. 2. Pus may be diffused through water, diluted sulphuric acid, and brine ; but mucus is not. 3. Pus is soluble in alkaline solu tions, and is precipitated by water ; hut this is not the case with mucus. These are the properties of pits when it is se creted from a sore which is said to be in good condition, or in a disposition to heal. Its properties are very different in what are called ill-conditioned sores. In these cases, the matter secreted is thin, fetid, and acrid. Matter secreted by cancerous sores, which has been examined, converts the syrup of violets to a green colour ; and from this matter sulphurated hydro gen gas is separated by means of sul phuric acid. This gas is supposed to exist in combination with ammonia.