180 Dr. Scliunck on Sugar in Urine, 



unnoticed, though it may, I think, serve to explain several phe- 

 nomena recorded in physiological chemistry, the cause of which is 

 still enveloped in obscurity. In a paper " On the Occurrence of 

 Indigo-blue in Urine*," I stated that when urine which is free 

 from sugar is mixed with sulphuric or muriatic acid and boiled, 

 it deposits a large quantity of brown flocks, and that the liquid 

 filtered from these nocks, after being made alkaline, gives the 

 reaction of sugar with salts of copper. Hence I inferred that 

 urine must contain some substance which, by decomposition with 

 acids, yields sugar, the brown flocks representing the body or 

 bodies with which the latter was originally associated in the 

 manner so well known to chemists ; and I ventured to surmise 

 that this substance might be the so-called extractive matter of 

 urine, regarding which so little is yet known. This supposition 

 has been fully confirmed by further investigation. My experi- 

 ments have led to the conclusion that human urine contains, as 

 Berzelius supposed, no less than three distinct extractive matters. 

 I have succeeded in separating these from one another, and from 

 the other constituents of urine. "When quite pure, their compo- 

 sition is uniform, even when they have been obtained from various 

 sources at considerable intervals of time ; and hence it is to be 

 inferred that, like urea and uric acid, they must be classed 

 among the last and simplest products of decomposition which the 

 tissues are capable of affording under the circumstances usually 

 occurring in the animal frame. When decomposed in watery 

 solution by means of strong acids, they yield brown pulverulent 

 or resinous bodies insoluble in water, which contain the whole of 

 the small quantity of nitrogen originally present, and a species 

 of glucose, which, though it has the composition and some of the 

 properties of grape or diabetic sugar, differs from the latter in 

 being uncrystallizable and insipid. 



The bearing of these facts on several important questions in 

 physiological chemistry will be apparent at once. The origin of 

 the sugar occasionally found both in health and disease in various 

 animal secretions is still a matter for speculation. It has been 

 surmised that it may be formed by the decomposition of albu- 

 minous substances ; but direct experiment has hitherto failed to 

 confirm this supposition. The extractive matters of urine, how- 

 ever, probably represent the missing link connecting the tissues 

 on the one hand with the sugar on the other ; or, in other words, 

 they contain that portion of the original complex (proteine) 

 which is capable of forming sugar, — the latter being no doubt 

 preserved by its association with nitrogenous matter from oxi- 

 dation, which would, if it were completely uncombined from 



* Phil. Mag. S. 4. vol. xiv. p. 288. 



