240 Proceedings of Boycd Society of Edinburgh, [march 19 , 
tion of 5 c.c. of blood. There is at first a slight cloudiness, the 
result of the formation of a fine precipitate, which may afterwards 
be seen adhering to the sides of the glass. After twenty-four hours 
a deposit of a light brick-red colour constitutes about four-fifths of 
the whole column. The supernatant fluid is clear, and contains 
no haemoglobin. Merely a trace of corrosive sublimate is to be 
detected in this clear fluid. The haemoglobin is carried down with 
the precipitate. 
Two c.c. of 25 per cent, solution of potassium hydrate added to the 
sublimate gives a slight yellow coloration. On the addition of 5 
c.c. of blood, the fluid becomes turbid and light in colour, but it 
rapidly clears up, at the same time becoming dark in colour, almost 
like dark-brown vinegar, the whole or the greater part of the preci- 
pitate disappearing. Even a few drops of the potassium hydrate 
is quite sufficient to dissolve the whole of the coagulated albuminate 
of mercury. After twenty-four hours the haemoglobin is reduced. 
The characteristic absorption bands are absent ; there is simply a 
darkening at both the red and violet ends, and a thin dark line in 
the yellow band. 
If 1 c.c. of tartaric acid be used, there is at first no precipitate, 
and very little alteration in colour. Later, a very filmy precipitate 
makes its appearance, the fluid becomes quite black and slightly 
viscid, especially near the bottom. The haemoglobin is completely 
reduced. It is difficult to determine the presence of the mercuric 
salt in the filtrate, on account of the dark colour of the fluid ; but 
if the stannous chloride be added, and the fluid be allowed to stand 
for a few hours, there is a distinct dark-brown precipitate, showing 
that a large portion of the mercuric salt is left in solution. At the 
end of three weeks this reaction is not nearly so definite, and it 
appears that partial oxidation of the mercury has taken place, 
giving rise to the formation of calomel. 
If caustic potash or soda be now added in excess to the mix- 
ture of bichloride, blood, and tartaric acid, there is no precipitate 
thrown down, whatever quantity of the alkali be used. The fluid 
becomes slightly viscid, and no haemoglobin can be detected. 
It is evident from this experiment that the albuminate, once dis- 
solved in tartaric acid, cannot again be thrown down, even in the 
presence of a large excess of an alkali. It should here be pointed 
