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tried to arrive at the conditions under which the quantitative deter- 
mination of SO, gives the most reliable results. “Wie einfach eine 
Bariumsulfatbestimmung auch scheint, so zeigt sich doch, dass in 
Wirklichkeit die Ausführung derselben um mehrere Ungenauigkeiten 
behaftet ist, die sogar trotz aller mögliehen Vorsicht gewöhnlich nicht 
vermieden werden können,” and then he gives a method which is 
rather complicated. Especially the presence of Calcium is objectionable. 
After these remarks it will not surprise us that the physiology 
and the pathology of the sulphur-economy have been little studied 
until now, especially if we consider that, except in urine the quantity 
of SO, in bodyfluids is exceedingly small. 
Therefore it was attempted to establish a miceovolumetrical method 
for SO, in the same way as it had been done for K. To known 
solutions of Na,SO,, HCl and BaCl, were added, both in known 
concentrations. Then it was determined: 
1. Whether, if the circumstances were the same, the same volume 
of precipitate was obtained. 
2. Whether the volume of the precipitate is influenced by: 
a. dilution of the fluid with water. 
6. the concentration of HC]. 
c. the quantity of BaCl, solution added. 
d. the presence of other mineral substances which may be met 
with in animal fluids, such as NaCl, KCl, Ca, Mg, and phosphates. 
It soon appeared that these factors strongly influenced: the volume 
of the precipitate. 
Mindful of what our K determinations had brought to light, we 
asked ourselves whether these unsatisfactory results were connected 
with or due to, the nature of the crystalline precipitate. Again we 
called in the help of the microscope It was indeed discovered that 
whenever we started from the same volume of SO, and yet different 
volumes of BaSO, were arrived at, this was always attended with 
another microscopic view of the precipitate. Now there were needles, 
now columns, sometimes they presented an appearance of crosses; 
but not only the shape differed, considerable differences in size were 
also manifest. And all this at the same temperature. Hence it was 
advisable to find the conditions under which the erystals always 
had the same size and shape. 
The investigations connected with the K determination had shown 
that in order to obtain useful results the crystals ought at any rate 
to be very fine. Here again it was attempted to satisfy this demand. 
An addition of some acetone was one of the chief means by which 
this result was attained. 
