DEXTROSE. 609 
small quantity of /5-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 /^-naphthol, gives a violel 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- 
taine'l that in the filtrate obtained after treating a normal urine in this way, 
no sugar reaction can he 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 
to 6 litres of the urine of healthy men with lead salts and ammonia, 
and by decomposing the precipitate so obtained witli 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 018 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, Centralbl.f. d. med. Wissenseh,, Berlin, 1888, Nos. 34 and 49. Also Luther, 
Chcm. Centr.-Bl., Leipzig, 1891, Bd. ii. S. 90 ; v. Udransky, Ztsehr.f.physiol. C'hcm., Strass- 
burg, 1888, Bd. xii. S. 380. 
- Loc. cit., p. 19. 
3 Deidsches Arch. f. klin. Med., Leipzig, 1890, Bd. xlvi. S. 252. A complete review of 
the earlier literature will be found in this paper. 
4 "Physiology of the Carbohydrates," 1894, p. 180 et seq. 
5 Ztsctir. f. physiol. Chem., Strassburg, 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, Joura. Physiol., Cam- 
bridge and London, 1896, vol. xx. p. 109. 
8 Arch./, d. ges. Physio!., Bonn, 1889, Bd. xliv. S. 306. 
VOL. I.— 39 
