32 Experiments on the Urine' [Jaw. 



composed sugar. Even in these latter products, however, a 

 portion of aairaonia exists, and may be obtained in a separate 

 form, hy first si^turating the liquid with pure potash, and then 

 submitting it to a second distillation. The condensed fluid will 

 invariably be found to contain volatile alkali, tliough often, it 

 must be acknowledged, in very minute quantity. It is on the 

 ammonia which comes over early in the distillation of diabetic 

 urine, that I am disposed chiefly to insist, as establishing the 

 presence of urea ; because we are unacquainted witii any other 

 animal substance which can give origin to the volatile alkali 

 under such circumstances. 



Another proof of the existence of some portion of urea in 

 diabetic urine, may, in many instances, be obtained by a careful 

 observation of the phenomena attending its spontaneous decom- 

 position. At a temperature exceeding 60^ Fahr. diabetic urine 

 passes rapidly to the acetous state. But if the succession of 

 changes be carefully watched, it will be found that there is a 

 point at which, before it becomes acid, it exhibits, to sufficiently 

 delicate tests, distinctly alkaline properties. 



In the account of ihese experiments I have not thought i 

 necessary to state the proportion of urea in the fluid submitted to 

 them, because the ingredients of the urine, whether in a healthy 

 or a morbid condition, will scarcely ever be found to have the 

 same proportion to each other. The deficiency of urea ia 

 diabetes, however, may be stated as being very considerable. Ia 

 those cases v/here I have attempted to estimate it, from the 

 quantity of ammonia evolved by the destructive distillation of 

 the urine, the urea has not appeared to exceed from to -^-^ the 

 quantity contained in an equal measure of concocted healthy 

 urine. One specimen of diabetic extract, with which I was 

 favoured by Dr. Bardsley, approached so nearly to perfect white- 

 ness, that there appeared to me little reason to expect any evi- 

 dence of its containing urea. Yet, even in the product of the 

 distillation of this extract, after being rectified with the addition 

 of potash, ammonia was found. On distilling, also, a portion 

 of the urine itself, the condensed liquor gave manifest traces of 

 carbonate of ammonia. This urine, however, contained a far 

 less proportion of urea than I had ever before ascertained ; not 

 exceeding, as nearly as I could estimate, of the natural 

 quantity. Making every allowance, then, on account of the 

 increased flow of urine, it will appear that the quantity of urea 

 discharged by persons labouring under diabetes, in any diurnal 

 interval, falls considerably short of the quantity voided in a state 

 of health. 



In the examination of dieibetic urine, when the disease has not 

 been completely formed, it has occurred to me to find, along 

 witli saccharine matter, sufficient urea to give a distinct precipi- 



