series of cases treated in this way, eleven out of twenty-one were aseptic. Some of this skin was from regions which are the hardest to deal with. As we gain experience and learn how difficult it is, and what strenuous exertions it requires to disinfect the skin, our results improve. In the next series the proportion of aseptic skin was rather higher. The skin of the lower limb was septic once in ten experiments. But the groin and scrotum were still unsatisfactory. The skin of the groin was aseptic five times, and septic six. The skin of the scrotum was aseptic eight times, and septic six. Taking all regions together, we found that in forty-one tests, twenty-six were aseptic and fourteen were septic, one of the latter having been tested twice. The limbs gave the best results; then the breast and abdomen; and the groin and scrotum the worst.1 But our later results are still better. Mr. Williamson disinfected the skin of the groin, scrotum, and abdomen twenty-one consecutive times, but of a total of forty-five experiments four were septic. These all came from the groin and scrotum; the skin of the scrotum having been tested thrice with one septic result, and the skin of the groin was tested twenty-five times and was septic thrice. We

Brit. Med. Journ., London, 11th July 1896.

again found the skin of the abdomen easy to disinfect. It was tested nine times before operations in the gall bladder, urinary bladder, ovaries, vermiform appendix, and uterus. It was aseptic in every case. The skin of the leg was aseptic twice, and the breast once. Later, when the results of the operations is mentioned, it will be noted that the septicity of the scrotal skin is not accompanied with a corresponding amount of suppuration. It is clear that we are gradually learning the best way of disinfecting the skin. But the nature of the problem is such that more will always depend upon the care with which the skin is prepared for disinfection than upon the kind of disinfectant which is applied.

After the skin has been disinfected, it has to be kept aseptic until the operation. For this purpose we place next to the skin a layer of 5 per cent. carbolic gauze, which has been soaked in biniodide of mercury lotion for at least twelve hours. This lotion contains 1 part of biniodide in 2000 parts of water. It is advantageous to use glycerine instead of water, but, as solutions of disinfectants in pure glycerine are inert, the whole of the water ought not to be replaced with glycerine. Dr. Black Jones and Mr. Furnivall grew bacteria from threads which had soaked for ten

minutes in fresh glycerine and carbolic acid, 1 part in 20. Glycerine and biniodide, 1 in 2000, and glycerine and perchloride, 1 in 1000, did not disinfect in one minute. The addition of glycerine keeps the gauze continually moist, and also helps the disinfectant to soak into the skin. This layer of wet gauze is covered with a layer of alembroth wool, and an outside dressing bandaged over the whole. The outside dressing should fit accurately, and may be used again after the operation. It consists of eight layers of 5 per cent. carbolic gauze, covered with a layer of waterproof jaconet. Its construction and

uses will be described when I come to the final

dressing of the wound. When there is a septic ulcer or sinus in the skin which has to be prepared for operation, the process of disinfection is much more difficult and uncertain. Not only should an attempt be made to disinfect such as these before the operation, but after the patient is anæsthetised they ought to be thoroughly scraped with a sharp spoon, soaked with pure carbolic acid, or touched with the actual cautery, irrigated with 1 in 1000 biniodide of mercury lotion, and shut off as far as possible from the field of operation by packing them with carbolic gauze. Sometimes a layer of gauze soaked in iodoform collodion seals the infected region, and affords

a fair protection. The only case I have lost from septicemia was infected from a cancerous ulcer which had not been properly disinfected. I was not then aware of the impotence of our chemicals.1

1 "Hunterian Lectures on Traumatic Infection," Edinburgh and London, 1895, p. 50 et seq.

CHAPTER XVII.

PREPARATION OF INSTRUMENTS.

THE preparation of the instruments has been mentioned more than once. The following suffice for almost every operation, namely, a knife, a pair of scissors, a pair of dissecting forceps, six to twelve pairs of pressure forceps, a straight needle, and a curved needle. For special operations, amputating knives, saws, bone forceps, blunt-pointed needles on handles, and such like may be wanted in addition, but the foregoing are the stock ones. All the instruments are put into boiling water for fifteen minutes. To each pint of water a teaspoonful of ordinary washing soda is added. This removes grease, prevents rust, and increases the temperature of the water. They are taken from the water without contamination, and arranged in a basin or tray filled with 2 or 2 per cent. carbolic lotion.

If the operation is at a distance, the instruments are boiled at home in a saucepan or small fish kettle,