This nineteenth century report briefly discusses the relation of glucose to picric acid which yields a useful reaction for the detection of glucose. It is stated that it is best to prepare a picric acid solution of the concentration used for the detection of prussic acid, so that there are 250 parts water to 1 part acid. One proceeds in the testing expediently by adding a few drops of picric acid to a glucose solution which has been mixed with some soda lye, and then heating the mixture to boiling. If the glucose solution was only somewhat concentrated, one will now obtain an intensely blood red fluid, while the color of thinner glucose solutions will be deep red. Since cane sugar does not demonstrate this behavior at all, a simple means to recognize the glucose in beet sugar and the like is derived. The author states that the practicing physician will be interested in the new reaction to determine whether a questionable urine is diabetic or not.