Quinine and Urea Hydrochloride. The use of this drug for purposes of local anæsthesia is still in the experimental stage. It is made by adding urea to a solution of quinine in hydrochloric acid. The crystals are soluble in their own weight of water. For the production of local anæsthesia it is used in strengths of ·25 to 1 per cent. It is free from toxic effects, and its solutions can be sterilised by boiling. The striking feature about this drug is the extraordinary duration of the anæsthesia, this being from one to six days. It has therefore been used by Crile and other American surgeons to prevent pain during the first few days after operation. The great drawback to its use, however, is that it causes a persistent indurated condition of the tissues which interferes with primary union, and which is sometimes followed by actual sloughing. In addition, it is now established that its use has been followed by tetanus in several cases, and it is recommended that a dose of antitetanic serum should be given immediately before or after the injection of quinine. Although the action of this drug is of great interest, it cannot be recommended at present for ordinary purposes. Adrenalin. Adrenalin is obtained as an extract from the suprarenal glands of animals. It is a greyish white powder, slightly soluble in water, and readily so in weak acids. The usual preparation is a 1 in 1000 solution of adrenalin chloride in normal saline. It contains ·5 per cent. of chloroform as a preservative. The drawback to the animal extract is that the solution does not keep well, decomposition being indicated by a brownish colour. Of late a synthetic preparation has been introduced, which appears to have the same action, and which can be sterilised by boiling. The action of the drug is to cause marked vaso-constriction by direct action on the vessel walls. It has no analgesic action, and is used as an addition to solutions of anæsthetic drugs. The advantages of its use are that the action of the anæsthetic is concentrated and prolonged, owing to the delay in absorption, and that the field of operation is rendered practically bloodless. In large doses it may produce toxic symptoms in the form of palpitations and breathlessness, or even actual syncope, so that care is necessary in its use. For purposes of local anæsthesia, it is added to the solution of the anæsthetic drug in the strength of 3 drops to the ounce, and large injections of this dilute solution may be made without risk. At least twenty drops may be safely given. Induction of Local Anæsthesia Local anæsthesia may be induced by the use of anæsthetic drugs in three ways--(1) infiltration anæsthesia, (2) regional anæsthesia, and (3) by application to a mucous surface or to the surface of the eye.