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Proceedings of Royal Society of Edinhurgli, [march 19 , 
It appears, however, as though in this case the whole of the mercury 
were converted into the white precipitate which is almost insoluble, 
and is an antiseptic of little potency. The blood is here simply held 
in suspension or solution in the aseptic, but not antiseptic fluid. 
(This is a point of some importance, as an aseptic fluid is of compara- 
tively little value in the treatment of a septic wound.) Haemoglobin 
absorption bands are very distinctly marked in fluid taken from any 
part of the glass vessel. 
If before adding the ammonia to the bichloride solution an excess 
of tartaric acid be introduced, there is no white precipitate formed, 
and none will make its appearance, however much ammonia be 
added. Weak potash or soda solutions may he added with similar 
results, no precipitate being thrown down even after the fluid 
becomes strongly alkaline. Similarly the white precipitate is dis- 
solved by a slight excess of tartaric acid, and the whole of the 
mercury is again thrown into solution, evidently retaining most of 
its antiseptic properties. In this respect mercury behaves with 
tartaric acid somewhat as do some of the metals of the copper and 
iron group, e.g., chromium, aluminium, iron, copper, zinc, lead, and 
molybdenum, — all of which, in combination with tartaric acid, are 
extremely soluble, and once so combined it is a matter of extreme diffi- 
culty to reprecipitate them (^.e., get them in an insoluble form). In the 
case of some it is necessary to fuse them before this can be done.* 
Citric acid acts in the same way, and it is in connection with this 
peculiar solvent action (amongst others) that chemists ascribe to those 
vegetable acids the character of an alcohol as well as of an acid. 
This action upon mercury has been apparently overlooked by most 
observers, for I can find no mention of it in any of the ordinary 
text-books on chemistry, and several authorities to whom I have 
spoken on the subject were unaware of it. Laplace, in the record of 
his experiments, makes no mention of the fact that tartaric acid will 
keep the bichloride of mercury in solution for a time, on the addition 
of this excess of an alkali. 
In making use of the second mercuric salt, biniodide of mercury, 
it must first be rendered more soluble. This is done by dissolving I 
* Since the above was read I have learned that some of these experiments 
have been repeated, and that Dr Dott has determined that in about a fortnight 
the tartaric acid converts the corrosive sublimate into the almost inert 
calomel. This is a point of great practical importance. 
