Apparatus for Estimating the Quantity of Glucose or Grape Sugar in Fluids.
Year: 1889

page_text: Date of Application, 25th Nov., 1889
Complete Specification Left, 5th Apr., 1890-Accepted, 31st May, 1890
PROVISIONAL SPECIFICATION.
Apparatus for Estimating the Quantity of Glucose or Grape Sugar
in Fluids.
I ALFRED WILLIAM GERRARD 1 Cantlowes Road Camden Square London
Pharmaceutical Chemist do hereby declare the nature of this invention to be as
follows
"
Glass or other tubes so graduated as to enable any operator working with the same,
to read at once from the tubes, the percentage of glucose or grape sugar present in
any fluid of unknown strength. Or the number of grains of sugar per ounce in the
fluids examined.
The tubes are cylinders engraved transversely at various points, having figures or
letters at those points to indicate proportion of grape sugar.
The tubes are fitted either with stop cock or pinch cock.
COMPLETE SPECIFICATION.
Apparatus for Estimating the Quantity of Glucose or Grape Sugar
in Fluids.
I ALFRED WILLIAM GERRARD, Chemist 1 Cantlowes Road Camden Square
London England do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement:-
The apparatus consists of one or more tubes made of glass or other material.
The tube or tubes may be of any length or circumference.
The apparatus generally has the form of a burette or burettes, on any surface of
which may be engraved. marked or printed, lines or points: The space between the
lines or points gradually widen or iitcrease in distance contiguous to or opposite each
line, figures or words are so placed. as to indicate percentages, parts by weight, or
parts by measure. The weights and measures may be of any denomination.
The figures or words engraved on the tube or tubes indicate or read as quantities of
glucose or grape sugar, so that any operator testing for the above sugars by the
ordinary methods and using the apparatus herein described is saved the trouble of
making any calculations of
any kind.
The method of graduating the instrument is based on the fact that using a constant
volume of alkaline cupric tartrate (Fehlings solution) it needs a larger volume of a
solution weak in sugar, to reduce the copper, than of a solution strong in sugar,
then having found the volume of solution of sugar equivalent to the required per-
centage of sugar, that volume is marked on the instrument as a percentage.-
Thus 10 c.c. of Fehling's solution are equivalent to and reduced by 05 gramme of
glucose; therefore if a sugar solution contains 10 per cent. glucose 5 c.c. of the sugar
solution will decolourise or reduce 10 c.c. Fehlings solution.
These facts enable me to get the following statement in proportions by means of
which I have been able to calculate the volume of sugar solution (diluted twenty
times) equal to any required percentage of grape sugar.-As 10: 10 :: 10 x, i.e.
x=10) c.c. Or again, as 9 10 :: 10: x, i.e. x=111 c.c. In each of these cases
the number of c.c. of sugar solution correspond respectively to 10 and 9 per cent. of
grape sugar.
The following table gives the result of a series of calculations made for finding
137

page_text: the amount of grape sugar in solutions of unknown strength. The sugar solutions
must be diluted with water to 20 volumes.
Amount of sugar
in solution.
10.0 per cent.
Volume of solution
(1 in 20) required to reduce 10 cub,
cent. of Fehlings solution.
-
10.0 cub. centim.
9.5
-
10-52
"1
"
"
"
9.0
-
11.1
"
39
"
"
8.5
-
11.76
">
"
"
"
8.0
-
12.5
"
22
""
"
7.5
-
13.33
"
"
"
"
7.0
-
14.28
"
""
"
"
6.5
-
15-38
"
"
"
"
6.0
-
16.66
23
"
"
"
5.5
18-18
22
"
"
"
5.0
20.0
"
"
"
"
To graduate the instrument it is filled with water and the water level marked with
a zero line, then the volumes of water represented by the right hand column of
figures in the preceding table are withdrawn in the order of their sequence, the
water levels after each withdrawal are then marked with their proper percentage, as
shown in the left hand column of figures of table. When once those figures are
placed upon the instrument any operator may employ it for glucose or grape sugar
estimation without using any calculations.
Having now particularly described and ascertained the nature of iny said Inven-
tion and in what manner the same is to be performed I declare that what I
claim is,―
1. Apparatus for estimating glucose or similar sugar without the need of making
calculations.
2. The marking of the said apparatus so as to indicate percentages, parts by
weight, or parts by measure.
Dated this 3rd day of April 1890.
ALFRED WILLIAM GERRARD.