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large quantity of a concentrated potassinm-cyanid solution also makes 
the sulfo-band disappear, but then only after some minutes. If to an 
SHb-solution an equal volume of a 1 °/, solution of CNK is added, 
at a temperature of 37° the S-band disappears only after three hours. 
By passing a current of CO, through a little serum from the boy 
and collecting this in a solution of lead-acetate or even in the sen- 
sitive reagent of Caro-FiscHpr we again failed to demonstrate sul- 
phuretted hydrogen in the serum. 
This induced us to discontinue the chemical tests with sulphuretted 
hydrogen in the serum, and try another method. With due caution 
to ensure sterility we allowed serum to act at 37° on a normal 
haemoglobin solution. It then appeared that in the majority of the 
tests a little sulphaemoglobin had been formed from the normal 
haemoglobin after a sojourn of 2 X 24 hours in the incubator. 
Now the idea suggested itself whether the serum might contain 
bacteria to which the formation of sulphaemoglobin could be ascribed. 
This idea had already occurred to GrBson *) regarding methaemoglo- 
binaemia and, indeed, this author achieved a positive result. Later 
experimenters, however, could not confirm it. A bacteriological 
examination of our patient’s blood, carried out by Mr. ScHaar also 
showed it to be sterile. 
We now allowed very small quanta of hydrogen sulphid to act 
upon normal haemoglobin-solutions; this yielded the sulphoband in 
the incubator at 37° only after a good deal of time (24 hours), the 
same result as had generally been obtained in the action of serum 
from our patient on normal haemoglobin-solution. We were justified 
in concluding from this fact, that small amounts of sulphuretted 
hydrogen must be contained in the serum. Supposing that by passing 
a current of carbon dioxid, too much of the small amounts of hydrogen 
sulphid would get lost to recover the rest, we resolved to react 
directly on the serum. Lead-salts did not answer our purpose as 
they precipitate protein, which tampered with our result. Various 
technical circumstances prevented us for the time from applying the 
most sensitive reagent of Caro-Fiscurr. We then had recourse to 
the reagent of Kran, consisting of a weak nitro-prussid-sodium 
solution in a soda-alkaline or ammoniacal environment. When 
adding such a solution to a solution containing a trace of hydrogen 
sulphid, a beautiful red, violet-tinged coloration comes forth. This 
reaction is believed to be less sensitive than the two others, never- 
theless we obtained pronounced results, when we applied it as a 
1) GiBson and DouerLas, Lancet, 1906, II. 72. 
