DEXTROSE. 609 



small quantity of /?-naphthol dissolved in chloroform is added, and then some 

 strong sulphuric acid. The latter, by acting upon the traces of sugar present, 

 produces furfurol, which, with the /3-naphthol, gives a violet or carmine-red 

 coloration. 1 This test is also affected by the presence of glycuronic acid. 



2. By treating the urine with mercuric acetate, creatinin and the various 

 non-saccharine reducing substances are precipitated. G. S. Johnson has main- 

 tained that in the nitrate obtained after treating a normal urine in this way, 

 no sugar reaction can be observed. A. H. Allen has, however, obtained posi- 

 tive results. 2 



3. By far the most satisfactory evidence is obtained by methods 

 capable of isolating any sugar that may be present. Moritz, by treating 

 5 to 6 litres of the urine of healthy men with lead salts and ammonia, 

 and by decomposing the precipitate so obtained with sulphuretted 

 hydrogen (Briicke's method), was able to isolate a substance which gave 

 all the reactions of grape-sugar. It was fermentable with yeast, yielded 

 phenylglucosazone crystals, was dextrorotatory, and reduced alkaline 

 copper and bismuth solutions. 3 Pavy, by a similar method, long ago 

 obtained a fermentable reducing body from normal urine, and he has 

 since extended his earlier results by showing that the substance yields 

 phenylglucosazone. 4 



When solutions of carbohydrates are treated with benzoylchloride, 

 they yield a precipitate of insoluble compounds (esters) with benzoic 

 acid. Glycuronic acid gives no precipitate. Baumann has applied this 

 fact to the separation of urinary carbohydrates ; and, in the hands of 

 Wedenski 5 and Baisch, 6 the method has yielded very convincing results. 

 The last observer decomposed the benzoic esters he obtained from 

 normal urine, with alcoholic soda, and isolated, inter alia, a sugar which 

 gave, with phenylhydrazine, an osazone melting at the right temperature 

 for that of glucose. The product gave also all the other reactions of 

 dextrose. The quantity found varied from 0'08 to 0*18 grms. in the 

 twenty-four hours. 



The evidence we have detailed leaves little room for doubt that 

 grape-sugar is a constituent of normal urine, and we may take the 

 figures just quoted from Baisch as the most accurate estimate we possess 

 of its amount. Pavy and v. Udransky found larger quantities, and 

 Seegen considerably less, but their methods are perhaps more open to 

 question from the quantitative point of view. 7 



Alimentary glycosuria. It is certain that many healthy individuals, after 

 a meal rich in sugar, and especially after the consumption of an excessive 

 amount of sugar in solution as in sweet wines and the like excrete tem- 

 porarily quantities of sugar greatly in excess of the small normal constant we 

 have just discussed. The explanation of this is probably to be found in the 

 observation of Ginsberg, 8 that when large quantities of sugar are present 



1 Molisch, CentralbLf. d. med. Wissensch., Berlin, 1888, Nos. 34 and 49. Also Luther, 

 Chem. Centr.-BL, Leipzig, 1891, Bd. ii. S. 90 j v. Udransky, Ztschr.f.physiol. Chem., Strass- 

 burg, 1888, Bd. xii. S. 380. 



' 2 Loc. tit., p. 19. 



3 Deutsches Arch. f. klin. Med., Leipzig, 1890, Bd. xlvi. S. 252. A complete review of 

 the earlier literature will he found in this paper. 



4 "Physiology of the Carbohydrates," 1894, p. 180 et seq. 



5 Ztschr. f. physiol. Chem., Strasshurg, 1889, Bd. xiii. S. 122. 



6 Ibid., 1894, Bd. xviii. S. 193 ; 1895, xix. S. 348 ; xx. S. 249. 



7 For a criticism of Briicke's lead-precipitation method, see Colls, Journ. Physiol., Cam- 

 bridge and London, 1896, vol. xx. p. 109. 



8 Arch.f. d. ges. Physiol., Bonn, 1889, Bd. xliv. S. 306. 



VOL. I. 39 



