NONEXISTENCE OF SUGAR IN DIABETIC BLOOD. ]35 



By addition of ten grains to the ounce, the crystallization 

 of the ?alts is entirely prevented, and the degree of black- 

 ness, and disposition to deliquesce are of course more mani- 

 fest than with smaller quantities*. 



As I was aware, that the sugar obtained from diabetic Sugar froin 

 urine is a different substance from common sugar (approach- ^^^^ ^^'^ ^J^* 

 ing more nearly to the sugar of figs), 7 had the precaution effects. 

 to repeat the same series of experiments upon serum, to 

 \ihich I made corresponding additions of dry sugar, that I 

 had formerly extracted from the urine of a person who void', 

 ed it in considerable quantity ; and I found the effects to be 

 perfectly similar in every respect. 



As a farther test of the absence or presence of sugar, I "fartheT tostd 

 found it convenient to add a little nitric acid to the salts, that 

 remained after crystallization of the drop. If the serum has 

 been successfully < oaguiated without any addition of sugar, 

 the addition of niiric acid merely converts the muriatic salts 

 into nitrates, and nitrate of soda is seen to crystallize with- 

 out foam or blackness. But when sugar has been added, a 

 white foam rises round the margin of the drop ; and, if far- 

 ther heat be applied, it becomes black in proportion to the 

 quantity of suaar present. 



Such are the appearances, when the proportions have been Difficulfies m 

 duly adjusted, and the proper heat for coagulation applied, *''^^"™''"'^^''" 

 I must own, however, that I could not always succeed to my 

 satisfaction, at the time when these experiments were con- 

 ducted ; and 1 am inclined to ascribe occasional failures to 

 having used more muriatic acid than was really necessary, 

 which by excess of heat might redlssolve a part of the 

 coagulated albumen, and thence occasion appearances, 

 which, without careful discrimination, might be ascribed to 

 sugar. 



After having, by this course of experiment, satistied my- t 



self as to the phenomena exhibited by serum in its natural 

 state, and the effects of any small additions of sugar, I then 

 proceeded to the examination of such specimens of diabetic 

 blood or of serum, as 1 was able to procure, 



♦ In Plate V, fig 6, are represented the degrees of blackness of the 

 ilrop occasioned by adding one, two, three, and four grains of sugar to 

 six drachms of serum. 



The 



