EXP. 4.--Ten grains of sulphur were administered in the same way to a fourth dog. On killing it and opening the body, the thoracic duct was found to be full. A considerable quantity of chyle was collected from it. Now, as it is asserted by some, that fat passes undissolved into the chyle, and as I believe that sulphur is digested in the neighbourhood of the bile duct, this chyle was chosen for analysis in preference to blood, as more likely to contain any insoluble sulphur. Besides, the blood would be less satisfactory, on account of the large quantity of albumen and fibrine contained in it, both of them also containing sulphur. The insoluble part of the chyle was obtained in the same manner as with the blood. It was then boiled in a small quantity of a weak solution of caustic potash. By this any free sulphur would be converted into a soluble sulphate of Potassium. The solution was filtered, and a few drops of a solution of the Nitro-prusside of Potassium added. (This is a salt lately discovered by Dr. Playfair. It is a delicate test for soluble sulphurets, with which it strikes a deep purple colour.) No change was produced. Therefore no insoluble sulphur was present in the chyle. The results of these experiments are thus in direct opposition to those of M. [OE]sterlen, and support a view of the question which seems even _à priori_ more philosophical and reasonable than that which he has adopted. I believe that no insoluble medicine can in any way gain entry into the blood without first undergoing solution in some way or another. PROP. IV.--_That some few remedial agents act locally on the mucous surface, either before absorption, or without being absorbed at all. That they are chiefly as follow:_-- _A. Irritant Emetics._ _B. Stomach Anæsthetics._ _C. Irritant Cathartics._