Vegetable Albumeriy Fat and Starch. 423 



matter closely corresponding with sugar is found in the sto- 

 mach. Experiment was scarcely necessary to prove that sugar 

 exists in the stomach, since as all flour and meal contain 

 sugar, it is obvious that when these articles of diet are swal- 

 lowed, sugar must be present in that viscus. But as it exists 

 in the stomach, it is natural to expect that it should pass into 

 the blood-vessels, and be capable of being detected in the mass 

 of the sanguineous circulation. That fermentation can be 

 excited by yeast in many of the fluids of the body, was long 

 ago shown by Tiedemann and Gnielin. Dr. A. Buchanan 

 during the course of last winter obtained traces of carbonic 

 acid from serum by fermentation, and I repeated the experi- 

 ments with success ; but I found it necessary to be careful in 

 such a delicate experiment that no source of fallacy should be 

 present to complicate the result, and that in order to arrive at 

 a demonstration of the presence of sugar in the blood, it would 

 be requisite to resort to weighing. For this purpose I em- 

 ployed what may be termed a saccharometer. It consists of 

 two light phials or flasks connected by a bent tube, one or 

 both of which possess a safety-tube. The serum or fluid to 

 be examined is weighed out in one of the flasks, which is placed 

 in a vacuum, or in hydrogen gas, to remove any carbonic acid 

 in solution, while into the other is introduced a solution of ba- 

 rytes, the bent tube dipping considerably under the surface of 

 the barytes solution. Yeast being mixed with the serum, the 

 connexion between the flasks is established, and the whole ap- 

 paratus placed in a warm atmosphere (70°). Fermentation 

 speedily begins if sugar is present, and the carbonic acid as it 

 passes over precipitates the barytes in the form of carbonate. 

 In twelve hours the action will be at an end ; the flask con- 

 taining the serum is then to be heated to carry over any CO2 

 which may remain in its atmosphere by means of vapour. I 

 prefer this method to using a safety-tube in the second phial, 

 because it is difficult to wash off" the carbonate of barytes which 

 is apt to adhere to the ends of the tubes. 



The carbonate of barytes is then to be thrown on a small 

 filter covered with a plate of glass, washed, ignited, and 

 weighed. Every 49 grains of it are equivalent to 22*5 of 

 sugar existing in the blood*. 



By means of this process, I found that the serum of a pig, 

 which had been starved for at least twelve hours, then fed on 



* The results contained in this paper were communicated to Prof. Liebig 

 in September 1844, He then suggested the mode of detecting sugar by 

 means of bile and sulphuric acid. I found this test to be ambiguous, as 

 sulphuric acid alone produced a red colour in diabetic urine and in other 

 animal Huids. 



