, 1889-07-20
Experiments with Chemical
Manures.
From Report By Prof. Harrison CIR.
BoreN, Barbados.)
PRELIMINARY EXPERIMENTS.

1EeSo were undertaken with the objects
of investigating the correctness of the
determinations of the relative proportions
OF sucrose and glucose remaining in the,
megass, made i'll previous years during
which we had assumed that no inversion,
or not any to an appreciate extent, had
occurred during the drying of the megass
for its preservation for analysis and as to
whether the experiments might not. with
advantage, be greatly simplifed by deter.
mining the composition of a few selected
canes from each plot, instead Of crushing
and drawing average samples Of juice and
megaSs from the whole OF those grown.
With regard to this latter object, we had
to ascertain the possibility O~fdrawing three
to six canes from five to eight hundred so
as to represent correctly the average com
position OF the whole number, and, as to
whether the loss of weight which ensues
upon keeping the canes b tween the time
OF their "utting and OF the analysis is due
only to loss of water, or is accompanied BY
loss OF sugars aS we'll. The canes expert
mentrd upon were selected at DOdds by
one OF us with great care their weights
determined immediately as cut, forwarded
tn the laboratory, and their sugar contents
aScertained by crushing the canes in a
small hand mill yielding, according to the
variety etc, from go to - per cent Of
juice. The sucroSe and glucose in the
expressed Juice and in the megass were
separately determined The sucrose by
the polariScope, the glucose by SOxhlet's
modification of feelings test. 1t was
found impossible with our mill complete
~ to extract the sugar from the megass by
repeatedly mOlStening with hot water and
expressing, even when this treatment was
pnSAan$nI TN ~ Ru,ol-o 49, 49,
tanned III the ~cOrtical portions of the me.
gass offering great resistance to extrac-
ton in this manner The mAgaSs, after
the sugars had been washed out as com.
pletely AZ we conveniently could do, was
cut mp finely, and either difflSed directly,
for from one to two hours, into a known
weight of water, or extracted in a modified
form of S0xhlet'S apparatus devised for
this purpose by one OF us. The additional
amour of sugars thus obtained where the
megaSS had been washed out as complete
ly aS possible by the mill varied from %
to TO 90 OF the weight Of the canes.
Eleven experiments were made in this way
for the determination Of the sugar ratios
IN the juice and III the megasS, the average
OF these showed that in the expressed
juice the relation of the SucrOSe to the
glucose was l to. O85, whilst in the megass,
it was l to. O81, showing that as the pro-
portion of glucose to sucrose is very much
higher in our dried samples of megass
than it is in the freshly expressed Juice,
our assumption, of no appreciable inver-
sion having taken place during the pre-
paration for preservation of the megass
samples was incorrect, and that, practical
ly, the ratio of sucrose to glucose in the
expressed juice and in the megass is the
same. The quantities of these constitu-
ents remaining in the samples of megass
analysed, have, therefore, in each case
been calculated to the ratio found in the
corresponding expressed juices. Several
experiments were made to test the pro.
liability of drawing samples of a few canes
SO that their composition should represent
fairly the average composition of a large
number. This We found, in practice, inn
possible to do, az is shown by the follow
ing determinations made upon three lots of
Bourbon canes, four to six in each lot, cut
at the same time, and selected from the
same plot as being, TO the eye, nearly
identical in character 3
NJ So9 of ssS Ss ' IN saspl. $50
Weight of sample 3olba 15ozs 29Ibs lot 42bs liz 1 ton IT icw&
Weight of cane lbs ia !" Tbs St Tbs 6lbs 81 oss.
Per. CT. Glucose SO 90 rs SO
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