BULLETIN OF THE BUSSEY INSTITUTION. 41 
> 
fine, spruce sawdust mixed with 0.4 kilo. of molasses and 7 kilo. 
of cut hay ate the fodder freely, and digested 9.4 per cent. of the 
carbohydrates of the sawdust and 8.4 per cent. of its cellulose, 
or, together, 17.7 per cent., — against 12.9 per cent. of the carbo- 
hydrates and 23.1 per cent. of the cellulose (together 36 per cent.) 
in the straw of winter grain, when such straw was fed to the 
animals instead of the sawdust. He argues that, in times of 
dearth, fine, fresh spruce sawdust may well be used to replace 
straw in the rations of idle oxen, and that, when properly balanced 
by appropriate nitrogenous food, it may be regarded as possessing 
about one half the nutritive value of straw for maintaining oxen. 
The Lead Acetate Test for Mannose. 
Beside phenylhydrazin, there is another test for mannose that 
is excellent when applied to not too dilute solutions of the pure 
substance, but is of only limited applicability because of the 
liability that it will be interfered with or even vitiated by the pres- 
ence of substances other than mannose in the matters to be tested. 
Reiss* has insisted strongly on the fact that, among all the sugars, 
mannose (‘‘ seminose”’) alone yields a precipitate when a neutral 
aqueous solution of it is mixed with a solution of basic acetate of 
lead. Although this mannose-lead precipitate has a decidedly 
characteristic appearance, and in spite of the fact that it is men- 
tioned as a test in the standard text-books,t comparatively little 
attention seems to have been paid to it by chemists. I was sur- 
prised at this silence when my attention was first directed to the 
subject, for it is evident that the test is an excellent one when 
applied under fit conditions; but on seeking to apply it more 
freely I soon discovered a very serious difficulty in that almost all 
samples of the sugars obtainable in commerce, even those reputed 
to be chemically pure, contain traces of impurities which in 
presence of the basic lead acetate may cause cloudiness, faint 
precipitation, or sometimes a precipitate so distinctly appreciable 
as to preclude the possibility of testing for mannose in such solu- 
* Landwirthschaftliche Jahrbiicher, 1889, 18. 753, 754. Cf. E. Fischer 
and Hirschberger, Berichte der deutschen chemischen Gesellschaft, 1889, 
22. 1155. 
+ For example, in Lippmann’s Chemie der Zuckerarten, page 335; and 
Tollen’s Handbuch der Kohlenhydrate, 2, 115. 
