It is my intention, shortly, to give a full account of the action of these medicines upon the various forms of disease to which the eye is subject, and also what particular disease each medicine is best calculated to remove. At the same time I shall state such instances of failure as have occurred in my experience, in order that a just estimate may be formed of the value and importance of each medicine. It may not be out of place here to state, that I have employed, with great success, the bisulphuret of carbon to enlarged indurated lymphatic glands. In the first instance, I rubbed equal quantities of the bisulphuret of carbon and alcohol upon the parts affected, but without any effect upon the glands. But as its effects were so great when its vapour was confined to the eye, I was led to apply it in the form of vapour, and by means of glass bottles similar to those I have described. By these means I excluded the action of the medicine from the external air, and thereby prevented its speedy evaporation. When it had been applied about one minute, the patient felt the part very cold, but immediately after a gradual heat, accompanied with great prickling; the heat increasing the longer the medicine was kept in contact with the part, until it could be no longer endured. On removing the glass, the part was red to an extent two or three times greater than the part enclosed. In a few days the change in the size of the glands was very great; and by its daily repetition, a complete and speedy removal of the disease was effected. I also find that its action upon diseased glands is more decided if the surface of the skin is well moistened with water previous to the application of the bottle to the part. The water, in fact, not only prevents the escape of the vapour between the glass and the skin, but assists the imbibition of the carbon; a point of the highest importance, inasmuch as all its action on the part depends upon the exclusion of the atmosphere from the vapour. I may here observe that these applications occasion no injury whatever to the skin. I have also found the _bisulphuret of carbon_, and the chlorocyanic acid, valuable medicines in the removal of deafness, depending upon a want of nervous energy and deficiency of wax. The mode of its application is substantially the same as that which I employ in diseases of the eye, with this difference only, that the bottle is formed with a small neck and stopper adapted to the size of the orifice of the ear, and held close to the organ until a considerable degree of warmth is produced. The action of these medicines, which contain so large a share of carbon, arises from the carbon in the vapour permeating the cuticle, and coming in contact with the oxygen in the vessels, which is conveyed through every part of the frame by inspiration and otherwise, and thereby forming carbonic acid gas, which evolves heat in the ratio of the quantity consumed by the oxygen.