326 FURTHER OBSERVATIONS ON 



the fabric ; at the same time, it is attached to the cyanide, for it is precipitated 

 b}^ it. We can thus understand that the dye may act as a go-between, attaching 

 the cyanide to the fabric by virtue of its affinity for the fabric on the one hand and 

 for the particles of the cyanide on the other. The mode of attachment is altogether 

 different from that by starch, but the thing is done nevertheless. It seems to 

 me astonishing that the dye should have this power. The quantity of gentian 

 violet used is exceedingly small. We take, say, twenty grains of the salt, and 

 diffuse it in sixteen ounces of a liquid containing only i-5o,oooth part of the 

 dye, draw a piece of the fabric through it, and so charge it with the requisite 

 amount of the cyanide. If now we consider what proportion the gentian violet 

 bears to the cyanide which it fixes, we find that there is only about one grain 

 of the dye to 140 grains of the salt. But more than that, the molecule, the 

 atom of the dye, is an exceedingly complex and heavy one ; so that if we consider 

 how many there are in comparison with the atoms of the cyanide which it fixes, 

 we find that there is only one molecule of the dye to nearly 600 molecules of 

 the cyanide salt. It is simply wonderful that each molecule of the dye should 

 have the power of fixing such a multitude of other molecules. It seems another 

 instance of what I have ventured to call solid solution. It is not a chemical 

 combination ; it is not a combination of one atom with one atom, but it is an 

 attachment of one molecule with a multitude of other molecules. I have often 

 contemplated with amazement the familiar fact of the solution of a soluble salt 

 in water. Put a bit of common salt into a tumbler of water, and, as everybody 

 knows, it will be quite uniformly distributed in a second or two. This marvellous 

 fact implies that every molecule of the chloride of sodium has an area of a mul- 

 titude of molecules of water in relation to it. If there were not the arrangement 

 of a definite number of molecules of water round every molecule of chloride of 

 sodium, there would not be an equable solution. So, I conceive, on the same 

 sort of principle, without chemical combination, this dye influences a multitude 

 of particles of cyanide in its vicinity. Here is a piece of gauze charged in the 

 way I have described, and you notice its delicate violet tint ; and we have the 

 satisfaction of knowing that, wherever we see the dye, there is the antiseptic 

 salt. You also observe that, when freely handled, it does not dust materially. 

 Thus we have the two advantages combined, one of which I had not hoped for — 

 that while we have the material dyed so as to show its presence by its tint, it 

 is also prevented from dusting. 



Note. — After the above paper had been read, I was mortified to find that 

 some gauze charged by aid of gentian violet dusted to a very inconvenient degree. 

 This appeared to be due to the influence of the bichloride of mercury, which was 



