AN ADDRESS OX A NEW ANTISEPTIC DRESSING 315 



greatly in liability to this irritation. The iodide of mercury, which is so very 

 slightly soluble, as you know, in water, is much more soluble in serum, and the 

 solution in blood-serum becomes irritating. In consequence of this, we had 

 the same disadvantages from irritation as we had with the alembroth ; and 

 although, as in the case of the alembroth, this was only a transient inconveni- 

 ence, I became dissatisfied with the iodide-of-mercury gauze. There was, 

 however, one point of considerable interest, both theoretically and (as it turned 

 out afterwards) practically, which we found in this investigation with the iodide 

 of mercury. If we simply charged with iodide of mercury, say, from a solution 

 in spirit of wine, and then applied the gauze so prepared, we found that the 

 particles of iodide of mercury tended to gravitate down towards the skin, and 

 there produce the most fearful irritation. It was absolutely necessary that 

 it should be fixed. I tried various means, and among the rest a solution of 

 starch, and then there came out this remarkable fact, that if a solution of starch 

 is used with one of the ingredients employed for forming the biniodide of 

 mercury by mixing a solution of iodide of potassium with solution of bichloride 

 of mercury — if you dissolve the iodide of potassium in a weak solution of starch 

 — the iodide of mercury thus formed in the nascent state associates itself 

 with the starch particles in the most intimate manner, and the starch becomes 

 entirely precipitated along with the iodide of mercury. If you take a drop of the 

 red fluid formed by mixing these two solutions, and place it on a piece of calico, 

 the watery material is absorbed by the calico and passes into the surrounding 

 parts without colouring them, while the red spot with its insoluble iodide 

 remains. If now you take a little iodine water, and apply it to the part of the 

 calico moistened by the fluid that has exuded, you find that the iodine water 

 produces no blue colour of iodide of starch, showing that there is no starch in 

 the fluid that thus oozes out and leaves the iodide of mercury behind ; whereas, 

 if you take a solution of starch and apply it as such to a piece of fabric, as far 

 as the fabric becomes moistened so far do you get a blue colour with the iodine. 

 Here we have, as it seems to me, a somewhat analogous case to the so-called 

 albuminate of mercury. We have the starch ])articles associated with the 

 particles of iodide of mercury ; the starch remains as such, the iodide of mercury 

 remains as such, still they are attached to each other. And so the result was that 

 when such a red solution produced by these two liquids was used for charging a 

 gauze, the iodide of mercury was stuck to the gauze by means of the starch, and 

 we had a most satisfactory arrangement in that respect. The iodide of 

 mercury could not be washed out by water, nor did it in the least dust out. The 

 value of this observation with reference to our present subject will appear shortly. 

 Being dissatisfied with the iodide of mercury, I turned my attention again 



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