g8 Dr. Wollaston on the Non-existence 
cause an increase of the quantity of oxalic acid formed, and 
secondly, that slight variations in the process for forming 
oxalic acid will unavoidably occasion differences in the result. 
The method which I employed appears to me capable of 
detecting much smaller quantities of such an ingredient, for 
though it might not enable us to distinguish exactly the nature 
of any small quantity that may be discovered, still the mere 
question of absence or presence admits of determination with 
great precision. 
For this purpose I investigated, in the first place, how the 
albuminous part of healthy serum could be most completely 
coagulated, and by what appearances the presence of sugar 
that had been added to it would be most easily discerned. 
When heat alone had been employed for the coagulation 
of serum, to which water had been added, that which exsuded 
from it was still found to contain a portion of albumen dis- 
solved in it, and if this were allowed to remain, any saccharine 
matter which might be present would be disguised, and could 
not with certainty be detected. 
I found, however, that this residuum of coagulable matter 
might be altogether prevented by the addition of a small quan- 
tity of dilute acid to the serum before coagulation.* To six 
drams of serum i added half a dram of muriatic acid previ- 
ously diluted with one dram and a half of water, and immersed 
the phial containing them in boiling water during four minutes. 
The coagulation was thus rendered complete. In the course 
of a few hours a dram or more of water exsudes from serum 
that has been so coagulated. If a drop of this water be eva- 
* I presumed that this portion of albumen was retained in solution by the alkali 
redundant in serum, and added the acid for the purpose of neutralizing it. 
