It will also be found, that the cases which have come under my treatment are, without exception, such as have been regarded either as hopeless, or at least such as have previously enjoyed, without sensible benefit, all the advantages of our best Ophthalmic Institutions. It cannot therefore be contended, that the ordinary treatment would have proved equally efficacious if it had been previously tried. I have also given the cases that are at present under my treatment, in order that all who take an interest in the subject may have ample opportunity of watching their progress, and forming, from their own observations, just conclusions. I have also added some important observations concerning the action of the essential oils on the eye, as exhibited both externally and internally. ACTION OF HYDROCYANIC ACID, &c. UPON THE EYE. In September, 1841, I made the following communication to the editor of the _Medical Gazette_, which he kindly inserted:-- It is a well-known fact, that the eyes of those who have been destroyed by hydrocyanic acid show none of the usual symptoms of dimness for a length of time after death.[1] On the contrary, the eye is clear and the pupil much dilated. This satisfied me that the acid exerted a specific action upon the eye, which might be made available as a medical agent for relieving many of the diseases to which that organ is so subject. [1] Morbid appearances produced by hydrocyanic acid in a case related by Hufeland. The inspection was made the day after death. The eyes were still glistening like those of a person alive; but the countenance was pale and composed like one asleep. The arteries and left cavities of the heart were empty, and the veins and right cavities distended.--_Christison on Poisons, page 708._ In most instances venous turgescence and emptiness of the arterial system is commonly remarked throughout the whole body.--_Christison on Poisons, page 710._ It appears that long after death the eye, as in Hufeland's case, has a peculiar glistening and staring expression, so as to render it difficult to believe that the individual is really dead; and this appearance has been considered by Dr. Paris so remarkable, as even alone to supply decisive evidence of poisoning by hydrocyanic acid.--_Christison on Poisons, page 711._