of Sugar in the Blood. 1 o i 
tracted. A little muriatic acid was then added, and sufficient 
heat applied for coagulation of the albumen. The water that 
separated after coagulation was found to contain the salts of 
the blood, but no trace whatever of sugar. 
A second specimen of dried blood, that had been ascertained 
to be diabetic on the same evidence as the preceding, was ex- 
amined in a similar manner, with the same result, as no ap- 
pearance of sugar could be discerned. 
In a third instance, I had some serum from the blood of a 
person whose urine had been tasted, and found “ very sweet." 
(I had no opportunity of procuring any of this urine for ana- 
lysis). After a portion of this serum had been coagulated, 
with the addition of the usual proportion of muriatic acid, there 
was no appearance whatever of sugar. But when three grains 
of diabetic sugar had been added to another ounce of the same 
serum, the presence of this quantity was manifest by the same 
process. 
I had also a fourth opportunity of examining serum of a 
person whose urine contained so much saccharine matter, that 
an ounce of it yielded, by evaporation, thirty-six grains of ex- 
tract. In this instance I was not so successful in my experi- 
ment ; for, though I was satisfied that no sugar was present, 
there certainly was a degree of blackness, which might have 
been occasioned by about one grain and a half of sugar in 
the ounce of serum. But this black matter appeared not to be 
sugar : it was more easily dried than sugar : it was not fu- 
sible by heat as sugar is : and its refractive power * was too 
great for that of sugar. 
* The method by which this was tried has since that time been described in the 
Philosdphical Ti ansae tions for 1802. 
