LIBRARY
UNIVERSITY OF CALIFORNIA.
Class
THE BREWER'S ANALYST
A SYSTEMATIC HANDBOOK OF ANALYSIS RELATING
TO BREWING AND MALTING
THE
BREWER'S ANALYST
A SYSTEMATIC HANDBOOK OF ANALYSIS
RELATING TO BREWING AND MALTING
GIVING DETAILS OF UP-TO-DATE METHODS OF ANALYSING ALL
MATERIALS USED, AND PRODUCTS MANUFACTURED,
BY BREWERS AND MALTSTERS
TOGETHER WITH
INTERPRETATION OF ANALYSES,
POLARISCOPICAL, MICROSCOPICAL, AND
BIOLOGICAL WORK
BY
R. DOUGLAS BAILEY, F.C.S., F.R.M.S.
WITH NUMEROUS ILLUSTRATIONS
OF THE.
UNIVERSITY
OF
FOKJJ^
KEGAN PAUL, TRENCH, TRUBNER & CO, LTD.
LONDON
D. VAN NOSTRAND COMPANY
NEW YORK
1907
[All rights reserved}
<-\0
^
't>'
UNIVERSITY
OF
I
PREFACE.
THE author's first work, dealing amongst other matters with the
analyses of brewing materials and products, was published sixteen
years ago, entitled Notes on Brewing, being a collection of the
more important of his articles contributed during several years to
the Brewers' Guardian. Since that time it has been his occasional
occupation to write articles on brewing for one of the trade
journals and to carry out analytical work for several large
brewing concerns. To this it may be added that for the past
eighteen years he has been daily employed in conducting practical
brewing and malting operations on an extensive scale, and can
therefore, with reason, claim to have a practical and scientific
knowledge of the subjects which his present work treats. So far
as he is aware, there are but two works dealing solely with
analyses relating to brewing one having been published so far
back as 1884, and slightly revised some six years ago, the other,
more recent, being a drawn-up course of laboratory studies for
the special use of the students at the Birmingham University.
There can be hardly any doubt under these circumstances that
there is at present a want for an up-to-date work for the use of
brewers and brewing students, and it is to supply this want that
the author has published the present volume.
Of late years there has been considerable controversy amongst
brewers' analysts as to the standardisation of analytical methods ;
and although nothing definite has so far been decided, the author
has borne the controversy in mind, and, in view thereof, has
endeavoured to steer clear of the same, and not vary the gener-
ally employed methods of analysis more than is consistent with
modern views, which have resulted in more accurate information
in the evaluation of brewing materials being obtained.
Details are given of the polarisation of light, a subject
neglected in all other works on brewing; particulars are also
given of the latest improvements in the polarimeter. A chapter is
Vi PREFACE
devoted to arsenical work, which is also of the greatest importance ;
whilst in the appendices is given a series of tables and typical
analyses which, it is believed, will prove extremely useful, par-
ticularly to those about to commence a laboratory course.
The author has left the consideration of the biological examina-
tion of water, malt, hops, and beer out of the part dealing with
methods of analysis, but has embodied the same in a separate
chapter on biological work, since an introduction to such a chapter
is necessary before a general idea of cause and effect in this
direction can be conveyed. Here will also be found particulars
of the microscope, the cultivation of single-cell yeast, the isolation
of bacteria, and other matters of general interest.
The author is indebted to Messrs Townsen & Mercer, 34
Camomile Street, London, E.G., and to Messrs Baird & Tatlock,
14 Cross Street, London, E.G., for the loan of blocks from which
numerous illustrations have been produced. The reader is
assumed to have a slight knowledge of theoretical chemistry, if
not of practical analytical methods, but the book is not intended
to replace any of the already numerous works on chemistry.
Finally, although the work is primarily intended for beginners,
it is anticipated that advanced students and qualified analysts
will find it useful as a work of reference.
K. DOUGLAS BAILEY, F.C.S., F.R.M.S.
LONDON, July 1907.
CONTENTS.
PART I.
PAGE
QUALITATIVE AND QUANTITATIVE ANALYSIS .... 1
PART II.
THE POLARIMETER 39
Polarisation of Light Specific Rotatory Power Solution
Weight Solution Factors Cupric Oxide Reducing Power
PART III.
CARBOHYDRATES AND ALLIED SUBSTANCES PROTEIDS OK AL-
BUMINOIDS AND ENZYMES 61
PART IV.
INDICATORS USED IN ALKALIMETRY 124
PART V.
PREPARATION OF STANDARD AND OTHER SOLUTIONS . . .127
PART VI.
METHODS OF ANALYSIS . . . . . . . 147
PART VII.
ARSENIC 270
PART VIII.
INTERPRETATION OF THE RESULTS OF ANALYSES 279
CONTENTS
PART IX.
MICROSCOPICAL AND BIOLOGICAL .
PAGE
326
PART X.
APPENDICES.
070
A. TYPICAL ANALYSES .....
B. TABLES AND FACTORS . . -
INDEX. ....... 407
LIST OF PLATES.
Plate
I. fig. 52. Solution Factors for Carbo-hydrates
at Various Densities
to face p. 60
II. {
I. JJ
53. Potato Starch \
54. Rye Starch J '
68
III. 1 "
I
55. Rice Starch \
56. Oat Starch J
68
IV. j
57. Maize Starch \
58. Pea Starch J '
68
H:
59. Tapioca Starch \
60. Sago Starch /
68
VI. f "
61. Barley Starch \
68
I
62. Wheat Starch /
VII. | "
63. Tous les Mois Starch \
64. Bermuda Arrowroot Starch J *
68
VIII.
80. Compound Microscope . . .
326
' ,, 85. Ped. acidi lacticf
,, 86. Sarcin a maxima
,, 87. Viscous Ferment
IX.-
,, 88. Bacterium aceti V .
,, 89. Lactic Ferment
,, 90. Bacterium lactis
,, 91. Bacterium termo
,, 92. Bacterium butyricum^
,, 93. Bacillus subtilis
,, 94. Bacterium ulna
X. -
,, 95. Bacterium leptothrix V
,, 96. Spirillum tenue
,, 97. Spirillum undula
^ , , 99. Mucor racemosus
XI / 98. Mucor mucedo 1
'I ,, 100. Mucor racemosus (submerged) /
XTT f 101. Odium lactis \
l '\ ,, 102. Penicillium glaucum J '
103 Burton Yeast \
104. London Yeast /
108. Saccharomyces Pastorianus, I
ix
.}
334
336
344
,, 346
348
358
LIST OF PLATES
Plate XV. j fi S' JJJ- Saccharomyces Pastorianus, II, )
(. ,, 110. Saccharomyces Pastorianus, III. /
XVI. -f" m< Saccharomyces ellipsoideus, I. 1
I ,, 112. Saccharomyces ellipsoideus, II. f
XVIII.
XIX.
XX.
XXI
'
( 113. Spore Formation: Saccharomyces 1
cerevisise, I. . . t *
| ,, 114. Spore Formation : Saccharomyces /
i Pastorianus, I. . J
115. Spore Formation: Saccharomyces 'l
Pastorianus, II. . . .
,, 116. Spore Formation: Saccharomyces J"
Pastorianus, III. . . . J
,, 117. Spore Formation: Saccharomyces^
ellipsoideus, I.
,, 118. Spore Formation: Saccharomyces f
ellipsoideus, II.
119. Film Formation
cerevisiae, I. .
120. Film Formation: Saccharomyces f
Pastorianus, I.
121. Film Formation
Pastorianus, II.
Pastorianus, III.
C 123. Film Formation: Saccharomyces^
XXII. -[ ellipsoideus, I. .
,, 124. lilm Formation: Saccharomyces f
t ellipsoideus, II. j
358
358
358
358
358
362
362
362
THE BREWER'S ANALYST.
PAKT I.
QUALITATIVE AND QUANTITATIVE ANALYSIS.
ANALYSIS is broadly divided into two classes, qualitative and
quantitative, the former consisting in processes for detecting one
or more or the whole of the constituents of a substance, the latter
in separating out one or more or the whole of the constituents
either in a pure state or in the form of some new substance of
known composition, and accurately estimating the quantity of
the product or products.
There are two methods by which this may be performed, the
first being known as
GRAVIMETRIC,
that is to say, separating out the constituents by gravity in the
form of a precipitate, collecting and weighing the same ; the
second method being known as
VOLUMETRIC,
consisting in submitting the substance to be estimated to certain
characteristic reactions, employing for such reaction solutions of
known strength, and from the volume of solution necessary for
the production of such reaction determining the weight of the
substance to be estimated by the aid of the known laws of
chemical equivalence. Both gravimetric and volumetric methods
are adopted in the analytical work described in subsequent pages,
and as the accuracy of both depend in the first place upon certain
principles, the employment of perfect thermometers, accurately
adjusted balances, weights, burettes, pipettes, measuring flasks,
etc., of definite capacity, and the use of certain forms of apparatus,
we may proceed at once to briefly consider the same.
1
.THE BREWERS ANALYST
means
1. The Bunsen burner (fig. 1) is generally employed in the
laboratory for heating purposes.
It is so constructed that the coal-gas, before being burnt, is
mixed with a proper proportion of air, which is drawn in through
holes at the lower part of the burner. The
flame is non-luminous, and is smaller than
the bright flame. It deposits no soot upon
a cool object. Its high temperature, non-
luminosity, and colourless appearance also
render it very valuable for producing flame
colorations. The burner is provided with
for partly or entirely closing the
air-inlets when requisite. This
is usually effected by turning
round a loose perforated ring,
which is slipped over the holes.
When the burner is to be used,
it is connected, by means of a
piece of tightly-fitting india-rubber tubing, about T \ths of an
inch in internal diameter, with the tube which supplies gas to the
working bench. The gas-tap is then turned on, and in a few
seconds the gas is lighted. The flame should be almost colourless,
and give scarcely any light.
When a small flame is used, the supply of air should be partly
FIG. 1.
FIG.
shut off, else the flame is apt to recede and burn beloiv. If this
should occur, the gas supply is stopped by pinching the rubber
tube, the supply of air is reduced, and the flame is then relighted.
The effect of partially or entirely closing the air-holes of the
burner should be learnt by experiment.
For diffusing heat over a large surface, a small perforated metal
cap, called the rose-top (a, fig. 1), is placed upon the top of the
QUALITATIVE AND QUANTITATIVE ANALYSIS 3
burner. It yields a circle of small tlames, and thus diffuses the heat.
Other forms of the burner are shown in figs. 2 and 3.
In country laboratories, where gas is not obtainable, a very
convenient form of burner is that shown in fig. 4, which is automatic
in action and constructed for burning methylated spirit contained
in the reservoir.
2. The Spirit-lamp is occasionally employed instead of the
gas or spirit burner ; but for general purposes it, or the methy-
FIG. 3.
ated spirit burner, should only be employed when coal-gas cannot
be obtained.
The spirit-lamp (fig. 5) consists of a glass vessel containing
methylated spirit, into which dips a cotton wick supported by
means of a brass or stone- ware wick-holder. When the lamp is
not in use, the upper end of the wick should be covered with the
glass cap, to prevent evaporation of the spirit.
3. Glass tube OP rod is CUt by making a deep scratch with
the edge of a three-cornered file at the point to be cut. The
glass is then held with both hands, and a gentle pressure is
exerted upon the glass as if trying to break it across. If the
file-mark has been made sufficiently deep, the glass will readily
break at this point. The sharp edges of a freshly-cut rod or
4
THE BREWER'S ANALYST
tube should always be rounded by holding them in the Bunsen
flame or blowpipe flame until they are partly melted, or by
rubbing them with the face of a file.
4. Glass tube is bent by holding it in the upper edge of
a common fish-tail gas-flame. The tube is constantly turned
slowly round on its axis, so as to heat all sides equally. As soon
as the glass is felt to be soft and pliable, it is quickly bent to
the required angle. The heated part must not be allowed to
touch anything until it is cold. It is then cleansed from soot
by means of a cloth.
A bend, if properly made, should be a curve, and should not
FIG. 6.
FIG. 4.
alter the bore of the tube. If a sharp angle is made, the bore
will be narrowed, and the bend, besides being unsightly, will be
very liable to break under a small strain.
Glass rod may be bent in the Bunsen flame or in the blow-
pipe flame.
5. The blowpipe is used for producing a small but very hot
flame. This is effected by blowing a fine stream of air through
an ordinary flame. The blowpipe (fig. 6) is held in the mouth,
and after the cheeks have been blown out to their full extent, the
air contained in them is forced out through the jet. This
produces a small-pointed, conical flame in the direction of the
blast. The chief difficulty in using the blowpipe properly is
experienced in maintaining the blast of air uninterrupted by the
respiration. The cheeks are kept inflated with air, so that the air
QUALITATIVE AND QUANTITATIVE ANALYSIS 5
may be forced through the blowpipe by the pressure of the
cheeks alone, and not by the action of the lungs. Breathing is
carried on meanwhile through the nose ; and the cheeks are
occasionally replenished with air from the lungs.
It is frequently necessary to have both hands free while the
blowpipe is being used. This "may be secured by resting the jet
on the top of the burner.
A blowpipe which is fed with air from a foot-bellows (fig. 7),
or from a mechanical or water blower, is often indispensable for
maintaining a high temperature, or for extensive glass-working
or glass-blowing.
6. Small Ignition Tubes. A piece of hard glass tubing,
FIG. 7.
five inches long, is drawn out at its middle point by heating it
strongly in the blowpipe flame. While the tube is being heated,
it is constantly turned round upon its long axis, and when
softened, it is gradually drawn out by pulling its ends in
opposite directions. By heating the conical parts successively
in the blowpipe flame, the narrow tube may be drawn off, and
two small closed tubes obtained. If the closed end of the tube
is strongly heated in the blowpipe flame, and is then gently
blown into while it is red-hot, it may be expanded into a small
bulb.
Small test-tubes, three inches long by half an inch in diameter,
will also serve for ignition tubes (fig. 8).
7. Mounted Platinum Wires. Two pieces of platinum wire,
each about two inches in length, should be fixed in glass handles
in the following way : Draw out a piece of glass tube, five inches
6
THE BREWER'S ANALYST
in length, at its middle point, and cut it across at the middle
of the narrow portion. Each piece of glass thus obtained serves
for the handle of a wire. Break off the narrow part of the tube
until it extends only about a quarter of an inch from the shoulder.
Insert the end of the platinum wire into this narrow opening ;
and hold the end of the tube in the blowpipe flame until the
glass melts and thickens around the wire, fixing it firmly
when cold. Then roll the free end of the wire round a stout
wire, so as to shape it into a loop about the eighth of an inch
across.
8. Glass Stirringf-RodS- Cut some glass rods into lengths
of three, six, and seven inches. Heat both ends of each of these
rods to redness in the blowpipe
flame, the rod being meanwhile
constantly turned round on its
long axis. The sharp edges are
thus removed. The end of the
rod must not be allowed to touch
anything until it is cool. If a
very thin glass rod is required,
FIG. 9.
FIG. 10.
heat part of an ordinary rod in the blowpipe flame until it is soft,
then draw it out to the requisite degree of fineness.
9. Corks are bored by means of the cork-borer, which is a
brass or steel tube sharpened at one end. These are of various
sizes, one fitting into another (fig. 9). A borer is selected
of slightly less diameter than the glass tube which is to be
inserted into the cork. The cork is then pressed against a
wooden surface, and the perforation is made by gently pushing
the borer through it with a constant movement of rotation upon
its axis.
QUALITATIVE AND QUANTITATIVE ANALYSIS 7
A convenient mechanical contrivance for boring holes through
corks and rubber stoppers is shown (fig. 10), several borers of
different sizes being supplied which may be conveniently screwed
to the apparatus as required.
A slender round file is used for smoothing the interior of
the hole made by the cork-bd'rer, and for slightly enlarging it.
Great care must be taken to leave the hole round in shape,
and not to enlarge it so much that the glass tubing, when
inserted, fits loosely. The cork-borer is sharpened by rubbing
the outer part of the edge obliquely with the face of a fine-
toothed file.
10. The Wash-bottle. A thin, flat-bottomed conical flask,
about eighteen ounces in capacity, and with a neck about an inch
in diameter, is fitted as is shown in fig. 11.
Select a sound cork which is slightly too large to enter the
neck of the flask. Roll it backwards and for-
wards under the foot with gentle pressure. When
the cork has been thus softened, it must fit tightly
into the neck of the flask.
Two pieces of glass tubing, rather longer than
would be required for the tubes, are then bent
(4) into the form shown in fig. 11. Their ends
are cut off to the right length, and the sharp
edges are rounded (3).
Two parallel holes are then made in the cork
by means of a cork-borer (9). The holes must
be somewhat smaller than the glass tubes, and may 'j,
be smoothed, and slightly enlarged, if necessary, by
the round file. Into these holes the tubes are then gently
pushed ; they must enter somewhat stiffly.
An india-rubber Stopper is much more durable than a cork
for this and for most other chemical purposes. It may be purchased
with two holes already made, or may be perforated by a sharp,
wetted cork-borer (9). Both the glass tubes and the inside of the
holes should be well wetted before the tubes are inserted, since water
serves as a lubricant for glass against rubber. Before the fitting
of the flask is proceeded with, insert the cork with the tubes into
the neck. Close one tube with the finger, and blow down the
other tube. A leakage of air is, as a rule, easily detected ; but by
wetting the outside of the cork, the escape of air-bubbles becomes
visible.
If the cork is air-tight, fit upon the long tube a piece of india-
rubber tubing about an inch in length. Into the other end
8
THE BREWER'S ANALYST
of this rubber tube push a short jet, made by drawing out a
piece of glass tubing in the blowpipe flame. The neck of the
flask may then be bound round with twine like the handle of a
cricket bat, or tightly covered with a folded strip of rubber or
other material. This renders it possible to handle the wash-bottle
when it is hot.
The wash-bottle is now nearly filled with distilled water, and
is ready for use.
Tap-water should not be kept in the wash-bottle. A fine stream
of water may be obtained from the jet by blowing down the
short tube. This stream serves for washing percipitates and for
other purposes. If a larger stream is required, the flask is in-
verted, when the water will flow out from the end of
the short tube, air entering meanwhile by the long
tube.
When hot water is required, the wash-bottle is
supported on a tripod stand upon a piece of coarse
iron-wire gauze, and is heated by the Bunsen flame,
or it may be placed on the water-bath (figs. 29, 30,
fl and 31).
It is preferable to have two wash-bottles, one as de-
scribed for hot water, the other of stronger build for
cold.
11. Cleaning 1 Apparatus. It is indispensable to
the success of an analyst that all glass and porcelain
apparatus should be scrupulously clean, and before
beginning to work, the student will do well to clean his
set of apparatus as directed below.
Test-tube Brush. This brush is constantly used for
/iff cleaning glass and porcelain apparatus. The piece of
FIG 12 s P n S e ordinarily fastened on the end of the brush does
not well adapt itself to the bottom of test-tubes and
boiling-tubes. A much more efficient end is given to the brush
by removing the sponge and bending back the end of the wire
stem sharply upon itself at a point just above where the hairs
commence (fig. 12).
Test-tubes^ beakers, and porcelain dishes are washed in a stream
of tap-water, their surface being rubbed meanwhile by the test-
tube cleaner. If the brush fails to remove a stain, hot dilute
hydrochloric acid may be used. Sometimes it is necessary to
heat a little strong sulphuric or nitric acid in a vessel in order
to cleanse it. Hot caustic potash solution may be used to remove
grease. In fact, when removing a substance from a vessel to
QUALITATIVE AND QUANTITATIVE ANALYSIS 9
which it strongly adheres, it should be treated by a liquid in
which it is easily soluble. Each article, after it has been carefully
washed with tap-water, should be placed upside down in a wicker
basket to drain.
Apparatus should be washed as soon as possible after use,
since the surface is more difficult to clean after standing.
Test-tubes containing liquids are placed in a test-tube stand.
After being washed, they should be placed to drain mouth down-
wards in the wicker basket.
Platinum foil and wire ar? cleansed by boiling them in hydro-
chloric acid and rinsing off the acid with water. The wire should
then be strongly heated for some time in the blowpipe flame,
until, when wetted with pure, strong hydrochloric acid and held
in the Bunsen flame, it no longer persistently colours the
flame. If the tip of the wire cannot be cleansed in this
way, it should be cut off. Commercial platinum is sometimes
FIG. 13. FIG. 14.
alloyed with barium or some other metal which colours the flame.
Wire made from such platinum is useless for flame-coloration
tests.
Instead of cleaning platinum foil and wire immediately before
use, it is better to keep them in a small beaker containing
moderately strong hydrochloric acid. The platinum, when
removed from the acid and rinsed with water, will then usually
be sufficiently clean for use.
Before putting apparatus away, it should be made a rule
to wash all glass or porcelain which is not in actual use,
and place it in the wicker basket to drain. The basket is
then put away with its contents. Dirty apparatus should never
be kept in the basket. AH iron apparatus should be carefully
dried, and must be kept in a dry place to prevent it from
rusting. Metal apparatus must never be put into the wicker
draining-basket.
12. Heating 1 Porcelain and Glass. The two follow-
ing rules must be attended to when either a glass or a
10
THE BREWERS ANALYST
porcelain vessel is being heated, in order to avoid the risk of
cracking it.
A vessel containing a liquid must never be heated by the flame
above the level of the liquid inside. A dry, hot vessel must be
allowed to cool before it is placed on a cool surface, and before
any liquid is poured into it.
Porcelain dishes (fig. 13) are generally used for the purpose of
boiling or evaporating liquids. They are supported on a pipe-
clay triangle or wire-gauze placed upon a tripod or retort-stand.
They may be safely heated by a small naked flame.
Porcelain crucibles (fig. 14) are used for containing solid
bodies which are to be strongly heated. They are supported in
the same way as porcelain dishes. The flame should not at first
be allowed to play steadily upon the bottom of the crucible so as
to heat it suddenly ; but the burner should be constantly moved
slightly from side to side until the porcelain is hot. The
crucible should be allowed to cool slowly on the triangle before
being removed. The hot crucible and cover are handled by
means of the crucible tongs (fig. 15).
Glass vessels require to be heated more cautiously than those
made of porcelain. A large naked flame must never be allowed
to play for any length of time on one part of
the glass surface. In heating a test-tube or
boiling-tube, this local heating is prevented by
holding the tube obliquely with the lower part
in the flame, and either moving it gently up and
down, or constantly turning it round on its axis.
Small quantities of liquid may be boiled in a test-
tube ; but for boiling larger quantities broader
boiling-tubes are better suited. The risk of burn-
ing the fingers by steam is avoided by bending
round the neck of the tube a strip of folded
paper, and pinching the ends of the strip together,
close to the tube.
Glass flasks are most safely heated by placing
them upon a piece of coarse wire-gauze on a
tripod stand. In many laboratories a sand-bath
is employed ; the flask may then be heated on the sand ; it is
better still, however, to heat the flask by placing it on the
water-bath.
13. Thermometers are instruments for measuring tempera-
tures. Owing to the imperfections of our senses, we are unable
to measure temperature by the sensation of heat or cold which
FIG. 15.
QUALITATIVE AND QUANTITATIVE ANALYSIS 11
they produce in us, and for this reason recourse must be had to
the physical actions of heat on bodies. These actions are of
various kinds, but the expansion of bodies has been selected as
being the easiest to observe.
Liquids are best suited for the construction of thermometers
the expansion of solids being too small, and that of gases too
great. Mercury and alcohol are the only liquids now commonly
used.
The mercury thermometer is the most extensively used. It
consists of a capillary glass tube, at the end of which is blown a
bulb a cylindrical or spherical reservoir. Both the bulb and
a part of the stem are filled with mercury, and the expansion is
measured by a scale graduated either on the stem itself, or on a
frame to which it is or may be attached.
The construction of the thermometer comprises three opera-
tions : the calibration of the tube, or its divisions into parts of
equal capacity ; the introduction of the mercury into the reservoir ;
and the graduation.
Division of the Tube into Parts of Equal Capacity. As the
indications of the thermometer are only correct when the
divisions of the scale correspond to equal expansions of the
mercury in the reservoir, the scale must be graduated, so as to
indicate parts of equal capacity in the tube. If the tube were
quite cylindrical, and the same diameter throughout, it would
only be necessary to divide it into equal lengths. But as the
diameter of glass tubes is usually greater at one end than
another, parts of equal capacity in the tube are represented by
unequal lengths of the scale. In order, therefore, to select a
tube of uniform calibre, a thread of mercury about an inch long
is introduced into the capillary tube, and moved in different
positions in the tube, care being taken to keep it at the same
temperature. If the thread is of the same length in every part
of the tube, it shows that the capacity is everywhere the same ;
but if the thread occupies different lengths, the tube is rejected,
and another one sought.
Filling the Thermometer. In order to fill the thermometer with
mercury, a small funnel is blown on at the top of the tube, and
is filled with mercury ; the tube is then slightly inclined, and the
air in the bulb is expanded by heating the bulb with a spirit-
lamp. The expanded air partially escapes by the funnel, and on
cooling, the air which remains contracts, and a portion of the
mercury passes into the bulb. The bulb is then again warmed,
and allowed to cool, a fresh quantity of mercury enters, and so on
12 THE BREWER'S ANALYST
until the bulb and part of the tube are full of mercury. The
mercury is then heated to boiling the mercurial vapours in
escaping carrying with them the air and moisture. The tube
being full of the expanded mercury and of mercurial vapour, is
then hermetically sealed at the open end, and when the thermo-
meter is again cooled, the mercury should fill the bulb and a
portion of the stem.
Graduation of the Thermometer. The thermometer being filled,
it requires to be graduated, that is, to be provided with a scale to
which variations of temperature can be referred. And, first of
all, two points must be fixed which represent identical tempera-
tures and which can always be easily reproduced.
Experiment has shown that ice always melts at the same
temperature whatever be the degree of heat, and that distilled
water under the same pressure, and in a vessel of the same kind,
always boils at the same temperature. Consequently, for the
fixed point, or zero, the temperature of melting ice has been
taken ; and for a second fixed point, the temperature of boiling
water in a metal vessel under the normal atmospheric pressure.
This interval of temperature, that is, the range from zero to the
boiling-point, is taken as the unit for comparing temperatures ;
just as a certain length, a foot for instance, is used as a basis for
comparing lengths.
Determination of the fixed Points. To obtain zero, snow or
pounded ice is placed in a vessel in the bottom of which there is
an aperture by which water may escape. The bulb or part of
the stem of the thermometer is immersed in this for about 15
minutes, and a mark is then made on the tube at the level of the
mercury and represents zero.
The second fixed point is determined by suspending the thermo-
meter in an apparatus designed so that water may be boiled and
the steam escape under ordinary atmospheric pressure. The
thermometer is thus surrounded with vapour, the mercury
expands, and when it has become stationary the point at which it
stops it marked. This is the point sought for.
The determination of the boiling-point of a centigrade thermo-
meter, viz. 100, would seem to require that the height of the
barometer during the experiment should be 29 '92 inches or 760
millimetres, for when the barometric height is greater or less
than this quantity, water boils either above or below 100 C.
But the point 100 C. may always be exactly obtained by making
a suitable correction. For every 27 millimetres' difference in
height of the barometer, there is a difference in the boiling-point
QUALITATIVE AND QUANTITATIVE ANALYSIS 13
of 1 degree. If, for example, the height of the barometer is 778
that is, 18 millimetres or two-thirds of 27, above 760 water
would boil at lOOf. Consequently, lOOf would have to be
marked, on a centigrade thermometer, at the point at which the
mercury stops.
Gay-Lussac observed that ..water boils at a somewhat higher
temperature in a glass than in a metal vessel ; and as the
boiling-point is raised by any salts which are dissolved, it was
assumed to be necessary to use a metal vessel and distilled water
in fixing the boiling-point. Rudberg showed, however, that these
latter precautions are superfluous. The nature of the vessels and
salts dissolved in ordinary water influence the temperature of
boiling water but not that of the vapour which is formed. That
is to say, if the temperature of boiling water from any of the
above causes is higher than 100 C., the temperature of the
vapour does not exceed 100 C., provided the pressure is not
more than 760 millimetres. Consequently, the higher point
may be determined in a vessel of any material, provided the
thermometer is quite surrounded by vapour, and does not dip
in the water.
Even with distilled water, the bulb of the thermometer must
not dip in the liquid ; for it is only the upper layer that really
has the temperature of 100 C., since the temperature increases
from layer to layer towards the bottom in consequence of
increased pressure.
Construction of the Scale. Just as the foot-rule which is
adopted as the unit of comparison for length is divided into a
number of equal divisions called inches, for the purpose of having
a smaller unit of comparison, so likewise the unit of comparison
of temperatures, the range from zero to the boiling-point, must
be divided into a number of parts of equal capacity called degrees.
On the Continent, and more especially in France, this space is
divided into 100 parts, and this division is called the Centigrade
or Celsius scale, the latter being the name of the inventor.
The degrees are designated by a small cipher placed a little
above, on the right of the number which marks the temperature,
and to indicate temperatures below zero the minus sign is placed
before them. Thus - 15 signifies 15 degrees below zero.
In accurate thermometers the scale is marked on the stem
itself. It cannot be displaced, and its length remains fixed, as
glass has very little expansibility. The graduation is effected by
covering the stem with a thin layer of wax, and then marking the
divisions of the scale, as well as the corresponding numbers, with
14 THE BREWER'S ANALYST
a steel point. The thermometer is then exposed for about ten
minutes to the vapours of hydrofluoric acid, which attacks the
glass where the wax has been removed. The rest of the wax
is then removed, and the stem is found to be permanently
etched.
Besides the Centigrade scale, two others are frequently used
Fahrenheit's scale and Reaumur's scale.
In Reaumur's scale the fixed points are the same as on the
Centigrade scale, but the distance between them is divided into
80 degrees instead of into 100. That is to say, 80 degrees
Reaumur are equal to 100 degrees Centigrade; 1 degree
Reaumur is equal to ^^ or f of a degree Centigrade ; and 1
degree Centigrade equals T 8 ^ F or i degrees Reaumur. Con-
sequently, to convert any number of Reaumur's degrees into
Centigrade degrees (20 for example), it is merely necessary to
multiply them by f (which gives 25). Similarly, Centigrade
degrees are converted into Reaumur by multiplying them by -|.
The thermometric scale invented by Fahrenheit in 1714 is still
largely used in England and elsewhere. The higher fixed point is
like that of the other scales, the temperature of boiling water,
but the null point or zero is the temperature obtained by mixing
equal weights of sal-ammoniac and snow, and the interval between
the two points (the lowest then known) was thought to represent
absolute cold.
When Fahrenheit's thermometer is placed in melting ice it
stands at 32 degrees, and therefore 100 degrees on the Centi-
grade scale are equal to 180 degrees on the Fahrenheit scale, and
thus 1 degree Centigrade is equal to f of a degree Fahrenheit,
and inversely 1 degree Fahrenheit is equal to f of a degree
Centigrade.
If it be required to convert a certain number of Fahrenheit
degrees (95 for example) into Centigrade degrees, the number 32
must first be subtracted in order that the degrees may count
from the same part of the scale. The remainder in the example
is thus 63, and as 1 degree Fahrenheit is equal to -| of a degree
Centigrade, 63 degrees are equal to 63 x f or 35 degrees Centi-
grade.
If F be the given temperature in Fahrenheit degrees and C the
corresponding temperature in Centigrade degrees, the former may
be converted into the latter by means of the formula
(F-32)|=C,
QUALITATIVE AND QUANTITATIVE ANALYSIS 15
and conversely, Centigrade degrees may be converted into Fahren-
heit by means of the formula
-
5
These formulae are applicable to all temperatures of the two
scales, provided the signs are taken into account. Thus, to
convert the temperature of 5 degrees Fahrenheit into Centigrade
degrees, we have
In like manner we have, for converting Reaumur into Fahrenheit
degrees, the formula
and conversely, for changing Fahrenheit into Reaumur degrees
the formula
" I =R
More briefly stated we have :
F. to C., subtract 32, multiply by 5, and divide by 9.
F. R., 32 4 9.
R. F., multiply by 9, divide by 4, and add 32.
R. C., ;, 5 4.
C. R., 4 5.
C. F., 9 5, and add 32.
14. Balances. In a brewer's laboratory, a pair of scales as
shown (fig. 16), and weights ranging from J oz. to 2 Ibs. (fig. 17)
will be found extremely useful, especially in weighing barley,
malt, hops, sugar, etc., where extreme accuracy is not needed.
It is absolutely essential, however, that the laboratory be equipped
with a really good light and delicate balance (fig. 18) to carry
100 grams and turn easily and quickly when loaded, with a
weight of one- or two-tenths of a milligram (figs. 19, 20). The
balance consists of a perfectly rigid metal beam suspended near
its centre of gravity on a fulcrum, the substance under comparison
being suspended from pivots placed at either extremity of the
beam, equidistant from and in the same horizontal line with the
fulcrum in the centre. The beam usually rests, by means of a
triangular piece of steel termed a knife-edge, on a plate of polished
16
THE BREWER'S ANALYST
agate. At the beam-arms similar arrangements exist,, the knife-
edge in each case being reversed and supporting an agate plate,
from which depends a hook, with wires attached to and supporting
each pan. A small metal vane is fixed on the exact centre of the
FIG. 16.
beam above the central knife-edge, which, by being turned to the
right or left, compensates any inequality in the weight of the arms
or pans ; or, instead of a vane, a screw weight may be employed at
one end of the beam, the precise distance of which, from the
centre, may be adjusted as required. The movements of the
beam are indicated by a vertical pointer
which oscillates before a small ivory
scale fixed to the base of the pillar.
A balance of this description serves for
weighing small quantities of substances
to be tested, many of which are hygro-
scopic and need to be weighed quickly
and with great accuracy. It also serves
for testing the accuracy of pipettes and
burettes, and, in fact, for the prepara-
tion of standard and other solutions and
all gravimetric analyses, as mentioned in subsequent pages.
15. Weights and Weighing". The weights most convenient
for use in chemical experiments are those based on the decimal
or metric system. A box of weights (fig. 19) ranging from 100
grams to a milligram is most useful and sufficient for all chemical
purposes. Since these weights are either multiples or sub-
multiples of ten, the weight of a substance is most conveniently
written down in the decimal notation. Thus a weight of 10
grams, 6 decigrams, 4 centigrams, and 3 milligrams, would be
written 10*643 grams.
FIG. 17.
QUALITATIVE AND QUANTITATIVE ANALYSIS
17
The larger weights are usually made of brass, the smaller
ones of platinum or aluminium (fig. 20). Instead of employing
the very small milligram weight, a wide " rider " (a piece of
platinum wire in the shape & ), weighing 1 centigram, is gener-
ally used. This is suspended over the graduated scale along the
beam of the balance,, the scale" being graduated in ten divisions,
each of which corresponds to 1 milligram. The " rider " placed
on the extreme end or tenth division of the scale, immediately
over the axis of the pan, equals 1 centigram, or, what is the
FIG. 18.
same thing, 10 milligrams; placed on the fifth division, it equals
but half this amount, and so on. Sometimes the arm of the
balance is divided into twelve divisions, in which case the rider
weighs 12 milligrams. Each division, of course, then corre-
sponds to 1 milligram.
The following rules should be observed during the process of
weighing :
(a) Place the substance on the left-hand pan of the balance
and the weights on the right.
(b) No substance must be placed directly on the scale- pan.
(c) Most substances can be weighed on a watch-glass or in a
2
18
THE BREWER S ANALYST
small dish, which has been previously weighed, or balanced by
means of a counterpoise.
(d) A non-volatile liquid is weighed in a balanced beaker or
dish ; a volatile liquid is weighed in a stoppered bottle.
FIG. 19.
(e) The weights should not be handled by the fingers, but
should be lifted by a brass forceps.
(/) The weights should be placed on the pan in a systematic
manner. Commence with the heavier weights, and if they are
too heavy, take the lighter weights in succession until the correct
ones are found. This method attains the result more quickly
and certainly than a random selection of weights would do.
FIG. 20.
(g) Before placing a substance or weight on the balance,
always bring the beam to rest by means of the lever.
(h) A substance should be weighed while it is at the same
temperature as that of the room ; if it is much colder or hotter
than the surrounding air, the body will appear heavier or lighter
than it should do.
QUALITATIVE AND QUANTITATIVE ANALYSIS 19
(i) The substance may be considered to be balanced by the
weights when the pointer swings through equal distances on
both sides of the central mark on the graduated ivory scale
fixed at the base of the pillar of the balance.
Occasionally the balance requires a careful removal of its
various parts for cleaning. The greatest care should be exer-
cised in this matter ; the various parts should be placed on a
clean sheet of paper, carefully wiped with a chamois leather,
and returned to their positions. Weights may be cleansed in
the same manner, and on no account should they be scraped or
cleansed otherwise than in the manner directed, excepting the
smaller weights, which, if of platinum, may be passed through a
smokeless Bunsen flame which will remove any organic matter
which may have become attached after prolonged use. The
smaller weights, however, are sometimes
made of aluminium, in which case they
must not be heated.
The balance case should never be left
open when out of use, should be closed
while ascertaining the final weight of any
substance by means of the rider, and
neither weights nor any substance should
be allowed to remain on the pans for any
length of time.
16. The desiccator usually employed FlG 21
in a laboratory consists of a glass dish of
the form shown in fig. 21. In the bottom of the vessel sulphuric
acid is placed, and over this is fitted a perforated tray of metal.
The rim of the vessel is smeared with grease or vaseline, so that
when it is covered by the lid the atmosphere is excluded. Upon
placing a substance to be cooled, such as a crucible containing
a calcined precipitate, on the perforated tray, and then fixing the
lid so as to render the vessel air-tight, the crucible and its
contents are, in time, cooled to the ordinary temperature, the
sulphuric acid at the bottom of the desiccator absorbing the
moisture. Substances should not be weighed until quite cold.
Should they have been previously heated, they would, in the
ordinary way, have to be exposed for a long period to the atmos-
phere in order to become cold ; and since all bodies, on cooling,
attract moisture to their surfaces in varying degree, their weight
by reason of this becomes augmented. This applies with greater
force to bodies which cool but slowly and to them that readily
absorb moisture, so that the use of a desiccator becomes obvious.
20
THE BREWER'S ANALYST
Fused chloride of calcium is sometimes employed as a desiccating
agent in place of sulphuric acid. For the interior of the balance,
calcium chloride is preferable, since, should sulphuric acid be here
employed and be accidentally spilt, it would ruin the balance,
whereas the spilling of calcium chloride might do but little damage.
Calcium chloride is not, however, so good a desiccating agent as
sulphuric acid, and should not
be employed, on this account,
in the ordinary desiccator.
17. Burettes. These in-
struments are used for the de-
livery of accurately measured
quantities of any particular
standard or other solution.
They invariably consist of a
long glass tube of even bore,
throughout the length of
which are engraved certain
divisions corresponding to a
known volume of fluid.
They may be obtained in a
great many forms under the
names of their respective in-
ventors, such as Mohr, Gay-
Lussac, Binks, etc. The Mohr
burette, with india-rubber tube
and metal spring clip (fig.
22, a), is preferred to any
other, being simple, the
quantity of fluid to be de-
livered being regulated to a
nicety by the pressure of the thumb and finger on the clip, and
the instrument not being held in the hand, there is no chance of
increasing the bulk of the fluid by the heat of the body, and thus
leading to incorrect measurement. There is, however, a great
drawback to this instrument, viz., it cannot be used for per-
manganate in consequence of its india-rubber tube, which decom-
poses the solution ; nor can it be used for iodine or strong alkaline
solutions. In such instances it is therefore preferable to employ
a burette of the same kind, only fitted with a glass stop-cock,
as is shown (fig. 22, 6).
These instruments are usually of a capacity to hold 100 c.c. or
50 c.c., and graduated in tenths of a c.c.
FIG. 22.
QUALITATIVE AND QUANTITATIVE ANALYSIS
21
31
The burette is filled with liquid from the top, the lower end
being closed. A little of the liquid is allowed to flow out through
the rubber tube or tap, in order to sweep out air-bubbles. The
liquid is then allowed to gradually flow out until the curved
under surface, called the meniscus, just reaches the zero graduation
near the top of the burette. The appearance of the meniscus is
shown in fig. 23. The volume of liquid shown in this figure
would be read as 32 c.c.
When the burette is being used, the volume of liquid is read,
and the stop-cock is then opened. When the requisite quantity
of liquid has flowed out, the reading is again taken. The differ-
ence between the two readings will
give the volume of the liquid which
has flowed from the burette. A
light glass float known as Erdmann's
float (fig. 24) is sometimes used to j 30 1 1-^:30
facilitate the reading of the liquid
volume.
The float consists of an elongated
closed glass bulb containing a small
quantity of mercury, and having a
diameter slightly less than that of
the burette ; round this bulb is
etched a regular line. The position
of this line is read off on the burette. ^^ k^xjj a b
In titrating hot or boiling solu- FlG 2 3. FIG. 24. FIG. 25.
tions, the burette should not be
arranged directly over the utensil containing the hot liquid, since
the burette would be heated and an incorrect reading obtained.
It is advisable in such instances to attach to the end of the
burette, by means of rubber tubing, a piece of bent glass tubing,
so that the heat evolved does not come directly in contact with
the burette.
18. Pipettes. A pipette is used for delivering a small
volume of a liquid. It usually consists of a tube narrowed at
both ends. Two kinds of pipette are in general use : one (fig. 25, b)
serves to deliver a definite volume of liquid, in this instance 20
c.c. ; the other (fig. 25, a) is graduated throughout, and serves to
deliver fractions of 10 c.c.
In using the pipette, the liquid is drawn into it, by suction,
past the graduation mark, and is retained by placing the first
finger over the upper end. The pressure of the finger is then
slightly relaxed, and the liquid is allowed to flow out until the
22
THE BREWER'S ANALYST
lower curve of its surface (meniscus) just reaches the graduation.
The finger is then firmly pressed down again so as to arrest the
flow. When the liquid is to be "delivered" from the pipette, the
finger is removed or its pressure relaxed until the liquid has
flowed out. When the pipette is emptied, it is allowed to drain
further for a few seconds in a vertical position, so as to deliver the
liquid which adheres to its inside. In both the whole and
graduated pipettes the upper end is narrowed to about one-eighth
inch, so that the pressure of the finger is sufficient to arrest the
flow at any point.
The usual capacities are 5 c.c. or 10 c.c. graduated stem ; 5 c.c.,
c.c
GO
50 -
FIG. 26.
10 c.c., 15 c.c., 20 c.c., 25 c.c., 50 c.c., 70 c.c. and 100 c.c. to
deliver.
19. Measuring-Flasks. These indispensable instruments are
made of various capacities ; they serve to mix up standard solu-
tions to a given volume, and also for the subdivision of the liquid
to be tested, and are in many ways most convenient. They
should be tolerably wide at the mouth, and have a well-ground
glass stopper, and the graduation line should fall just below the
middle of the neck, so as to allow room for shaking up the liquid.
Convenient sizes are 50 c.c. (to deliver), 100 c.c., 200 c.c.,
250 c.c., 300 c.c., 500 c.c. and 1000 c.c. (1 litre), all graduated to
contain the respective quantities.
Graduated cylinders are shown (fig. 26) and glasses (fig. 27).
QUALITATIVE AND QUANTITATIVE ANALYSIS
The latter are graduated, as shown, to contain from 1 pint to
1 gill and also to show fluid ounces.
Cylinders are usually graduated throughout the greater part of
their length, the graduations indicating cubic centimetres, or
multiples of cubic centimetres, according to the capacity. They
may be obtained either closed Ijy a stopper, or open.
When the measurement of a volume of liquid is being taken,
FIG. 27.
the under surface of the liquid (meniscus) should be exactly level
with the graduation.
20. Filtration is generally performed by employing a glass
funnel (fig. 28) into which a folded filter paper is placed, adding
the solution to be filtered in such quantity as will
not fill the funnel more than three-quarters full at
any time.
Glass funnels of a diameter of three inches, the
sides of which should be perfectly regular and
inclined at an angle of 60 degrees, the stems
narrow and long and cut off at the end obliquely,
are the most convenient to employ.
The liquid to be filtered should be added to the
funnel containing the filtered paper, by allowing it
to gently run down a glass rod which should be held over the
funnel with one hand, the other hand decanting the liquid.
If the liquid were poured into the apex of the paper, loss by
spirting might result, and there is the danger also of the paper
itself becoming ruptured.
FIG. 28.
24 THE BREWER'S ANALYST
In most cases a portion of the precipitable matter in suspension,
or the precipitate itself, when passed on to the filter paper, is apt to
pass through the pores of the paper ; it is therefore advisable to
first see that the pores of the paper are filled before proceeding
to use the filtrate. A portion of the liquid to be filtered should
therefore be allowed to pass through the paper and then be
returned and refiltered. This is in numerous instances essential,
whilst in some cases it is necessary to first moisten the filter
paper with hot or cold water or weak ammonia before commencing
to filter.
The stem of the funnel should be arranged to touch the side
of the receptacle receiving the filtrate, so that splashing may be
avoided, and the speed of flow accelerated by capillary attraction.
Having transferred the whole of the precipitate to the filter
paper, the next operation is to wash it ; this is performed by the
aid of the wash-bottle (fig. 11). By holding the wash-bottle and
blowing through the short tube, the spray of water issuing from
the long tube may be directed against the upper edge of the
filter paper. Care should be taken, however, to moderate the
force of the flow so as to avoid rupturing the paper.
The funnel should not be refilled until the liquid previously
added has passed through. A precipitate usually requires three
thorough washings after the whole of the liquid has been passed
through the paper. This is a point of great importance, as
inattention to it is the cause of many worthless results.
Precipitates of a very gelatinous nature take a long time to
filter, and the process therefore becomes tedious. In order to
accelerate filtration in such instances, one of the simplest and
most efficacious ways is to take a rubber stopper through which
two holes are bored, fit it to a flask or bottle in the same manner
as in constructing a wash-bottle, pass the stem of the glass
funnel, through which it is intended to filter, through the hole
which would, in the case of the wash-bottle, be fitted with a piece
of glass tubing to almost the bottom of the flask, and through the
other hole pass the ordinary piece of bent tube. To the end of
this bent tube fit a small piece of india-rubber tubing and a metal
spring clip. Having inserted the folded filter paper in the funnel
and added the liquid it is intended to filter, place the mouth to
the end of the rubber tubing and apply suction, by which means
the air is withdrawn from the flask and a partial vacuum created ;
this facilitates the filtration, which, under such circumstances, is
wonderfully expedited. In fact, the most gelatinous precipitates
can be speedily and effectively filtered in this way. Care should
QUALITATIVE AND QUANTITATIVE ANALYSIS . 25
be exercised to only gently create the partial vacuum, as, otherwise,
there is great danger of rupturing the apex of the filter paper.
21. Evaporation. Liquids are easily evaporated by long-
continued heating or by boiling them in a porcelain or platinum
dish over a Bunsen flame. In these cases, however, there is the
liability of spirting, and with such liquids as beer, wort, sugar
solutions, etc., there is the disadvantage that their constituents
may, by this method of evaporation, caramelise. 1
It is best to avoid evaporation by direct flame, and in no
instance should alcohol, methylated spirit, ether, or liquids con-
taining the same, be subjected to such method of evaporation, as
they would undoubtedly catch fire.
Under these circumstances it is wisest in all cases to evaporate
liquids over the water-bath.
22. The water-bath (figs. 29, 30, 31) consists of a vessel
made of sheet copper fitting
into another vessel of the same
material, leaving a space
between the two around the
sides and bottom of about
1 inch, and at the top about
1J inch, so that water may
be added to nearly fill the
space. There are usually one
or two doors in front of the
vessel, the interior constitut-
ing a drying oven, so that
samples of malt, etc., may be
introduced and dried. On the
top of the vessel there are FIG. 29.
openings fitted with lids
(fig. 29), or a series of flat rings of varying diameter which fit one
on top of the other (fig. 30), so that the openings may be made
large or small to allow of the exact fitting of the utensil containing
the liquid to be evaporated. On the other hand, each opening is
fitted with an Iris diaphragm as shown (fig. 31).
A liquid to be evaporated is poured into a porcelain or platinum
dish and the dish placed on the water-bath. A Bunsen flame is
1 In evaporating liquids it should be remembered that both glass and
porcelain are attacked by many solutions, and thus error (sometimes serious)
may be introduced into analyses. The estimation of alkalies may be affected
by this cause. It is preferable, therefore, to employ a platinum dish for all
such purposes.
26 THE BREWER'S ANALYST
placed beneath the bath, and as the water boils the steam heats
the vessel containing the liquid being experimented with, and
evaporation is allowed to continue until the liquid is of the bulk
desired, or until it is completely evaporated.
In the analysis of malt, when the mash is made and placed on
the bath, it is necessary to maintain a constant temperature of
150 F. (65 '5 C.) for about an hour. In order to do this the
Bunsen burner employed for heating the water in the bath is
fitted with a gas regulator, so that the water may be maintained
at the proper temperature. The gas regulator is known as the
"thermostat."
FIG. 30.
23. Thermostat. The principle of this instrument consists
in the mercury, when heated, expanding, and closing the main
entrance of the gas.
Referring to fig. 32, a shows a T-tube ground to fit into the
wide part of a thermometer tube ; b shows a side gas exit tube,
and c shows a mercury bulb at the foot of the thermometer tube ;
s represents the side tube filled with mercury and fitted with a
metal screw ; A is a small hole in T-tube a opposite b. The gas
enters by a and passes through b to the burner. When the
temperature rises the mercury expands into the wide part of the
cylinder, closing the bottom a tube ; the burner is thereby
reduced, as it is only fed by the small hole in T-tube. S screw
regulates the heat. If a high temperature is wanted, then the
QUALITATIVE AND QUANTITATIVE ANALYSIS
27
mercury must be pressed down the tube to begin with, as it is only
when the required temperature is reached that the mercury should
rise as high as the widening in the tube, and shut off the excess
of gas above that which is required.
Owing to impurities in the gas, the mercury in time becomes
coated with a film, which affects the sensibility of the apparatus.
FIG. 31.
In order to remove this film, take out T-tube a, screw down
the mercury, and clean with a brush.
This regulator, known by the name of its inventor Reichert
is suitable for all temperatures. For very low temperatures
however, instead of a Bunsen burner, it is better
to use a burner with a very small opening, almost
the size of a blowpipe jet.
24. The Air-Bath. For driving off the water
of crystallisation from salts such as the residue
from water and with substances which do not
undergo change at very high temperatures, it is
usual to dry them off in an air-bath. This con-
sists of a box of sheet copper having a closely
fitting door. It is placed on an iron tripod and
heated by a Bunsen flame, the temperature
employed and regulated by a thermostat being
215-6 F. (102 C.).
25. Precipitates and Ignition. In some
cases it is necessary to weigh a precipitate col-
lected on a filter paper ; but before weighing, it j,
becomes essential to thoroughly dry it. In such
instances the glass funnel containing the filter paper and its
contents is placed in the water oven (22) and thoroughly dried,
28 THE BREWER'S ANALYST
after which the paper is removed from the funnel, folded, placed
under the desiccator (16) to cool, and afterwards weighed, deduct-
ing the weight of the unburned paper from the total weight found,
whereby we arrive at the weight of the precipitate.
In other cases it becomes necessary to subject the precipitate
to ignition. This is performed by folding the paper, placing it
in a small tared platinum dish or crucible (12), and burning it
by means of a small Bunsen flame. In such instances a triangle
made of wire, the three sides of which carry small pieces of pipe-
clay, is employed. This is placed on an iron tripod over a Bunsen
flame ; the crucible containing the precipitate is then placed on
the top, and ignition proceeded with, it is at all times advisable
to employ a small flame, and to arrange it so that the tip of its
inner blue cone approaches to within an eighth of an inch of the
bottom of the crucible. Experience has shown, in fact, that
inattention to this, such as the application of a large flame which
excludes atmospheric air and hence prevents oxidation, may
necessitate the ignition of a precipitate for several hours,
and that even then the ignition may be imperfect and the
precipitate not thoroughly burnt.
With a platinum crucible this would result in considerable
damage and loss of weight, thus vitiating the result in a two-
fold way.
After burning off in the proper manner, the crucible is placed
under the desiccator, and when cool, weighed, the weight of the
ash of the filter paper being deducted from the weight thus found.
26. Filter Papers. It is always advisable to employ filter
papers of the purest kind, that is to say, as free as possible from
saline bodies. There are now several kinds on the market, which,
when subjected to ignition, leave practically no weighable
residue, and obviously they are the best to employ.
The author uses and prefers the Swedish papers manufactured
by J. H. Munktell, a box of which contains 500 papers, each of
which, when reduced to ash, leaves no weighable residue. With
other papers it is necessary to know the amount of ash they leave,
so as to deduct this from the weight of a precipitate. The ash
will be less, however, when the liquid filtered is acid ; for example,
when dealing with a precipitate of boric sulphate, the filtrate of
which is acid, 1 milligram would probably be the correct differ-
ence ; whilst for lime, the filtrate of which is alkaline, the same
paper would give an ash of 2 milligrams. It is advisable there-
fore to prepare unknown papers by steeping them over-night in
a 5 per cent, solution of hyrochloric acid, afterwards decanting
QUALITATIVE AND QUANTITATIVE ANALYSIS
29
the liquid and washing the papers with distilled water until the
washings are neutral to litmus. Upon then drying the papers
in the drying oven, they will invariably be found, upon ignition,
to give no appreciable residue.
27. Distillation. There
are several forms of distilling-
or condensing apparatus. Fig.
33 shows Keene's, employed in
beer analysis, which consists
of a copper tube, curved at
the top, to the end of which
is attached the distilling flask
D. The straight portion of
the tube is surrounded by
a strong metal jacket through
which cold water is passed
during distilling, the water
entering at A and leaving at
B. The distilling flask D is
heated by an Argand burner
E, and the distillate is col-
lected in a plain or graduated
flask C.
Another form of distilling
apparatus is Thorpe's (fig. 34),
whilst a further form of yet
more ancient date is the well-
known Liebig's (fig. 35), still
employed, particularly in water
28. Density and Specific
Gravity. According to the
principle of Archimedes, every
body immersed in a liquid is
submitted to the action of two
forces gravity, which tends FIG. 33.
to lower it, and the buoyancy
of the liquid which tends to raise it with a force equal to the weight
of the displaced liquid. The weight of the body is either totally
or partially overcome by this buoyancy, from which it is con-
cluded that a body immersed in a liquid loses a part of its weight
equal to the weight of the displaced liquid.
If we take the density of distilled water at a given temperature
\
OF THE
UNIVERSITY
OF
30
THE BREWER S ANALYST
to be the unit, the relative density of any other substance is the
ratio which the mass of any given volume of that substance at
that temperature bears to the mass of an equal volume of water.
Thus, it is found that the mass of any volume of platinum is
22'069 times that of an equal volume of water; conssquently, the
relative density of platinum is 22*069, and this relative density
of a substance is called its specific gravity.
In order, therefore, to calculate the specific gravity of a body,
it is sufficient to determine its weight and that of an equal
FIG. 34.
volume of water at the same temperature, and then divide the
first weight by the second ; the quotient is the specific gravity of
the body.
In taking the specific gravity of a liquid or solid body,
a temperature of 39 '2 F. (4 C.) is often chosen, this being the
temperature at which water is at its maximum density ; for
water, unlike most other substances which contract between this
temperature and the freezing-point 32 F. (0 C.), expands.
It is exceedingly inconvenient, however, to have to bring bodies
to such a low temperature, so in ordinary practice a more readily
attainable temperature is chosen, namely 60 F. (15*5 C.).
The specific gravity of gases, however, is determined at the
QUALITATIVE AND QUANTITATIVE ANALYSIS ' 31
temperature of the air at the time of performing the experiment,
and the volume the particular gas would occupy at any other
temperature is found by calculation.
It is obvious that in practical brewing operations a method
of arriving at the specific gravity of a solution, requiring a
balance, weights and a specific- gravity bottle, is quite out of the
question. Instruments were therefore devised which will show
the specific gravity of solutions when immersed therein.
These instruments hydrometers and saccharometers are
well known to the practical brewer ; for instance, we have the
Sykes hydrometer, the indications of which are simply in degrees
of specific gravity over the weight of water. Thus 20 Sykes
correspond to 1020 specific gravity. We have also the Bates
FIG. 35.
hydrometer, which deals with true specific gravity ; thus with the
smallest counterpoise attached, which is 1000, or equal to the
weight of water and floating in a liquid to the graduation mark
of 20 on the stem, the specific gravity is 1020.
We have also the hydrometer of Twaddell, so graduated that
real specific gravity may be deduced by a simple method from
the degrees indicated, viz., multiplying the latter by 5, and
adding 1000; the same being the specific gravity, water being
1000. Thus 5 Twaddell indicate 1025 specific gravity. Again,
we have two different instruments under the name of Baume, one
being for liquids heavier than water, the other for those lighter
than water, the specific gravity being calculated as follows :
To convert degrees Baume into specific gravity, deduct the
degree indicated from 144, and then divide 144 by the number
so found and multiply by 1000.
32 THE BREWER'S ANALYST
Thus to convert 20 Baume into specific gravity
144-20=124.
144 -r 124=1-16129.
1-16129 x 1000= 1161-29 specific gravity.
We have also the saccliarometer of Balling, graduated to indicate
the percentage of dry, solid matter in the liquid ; and the Dringe
and Page saccharometer, graduated to show pounds per barrel.
Thus water weighs 10 Ibs. to the gallon, so that a barrel of 36
gallons weighs 360 Ibs. Should a barrel of beer weigh 380 Ibs.,
the indication by the saccharometer would be 20 Ibs, that is, the
excess weight over the natural barrel of water.
To convert specific gravity as found by any of the former
mentioned hydrometers into pounds per barrel degrees, it is
merely necessary to multiply the excess weight over 1000 by '36
or divide by 2 '7 7. Whilst to convert pounds per barrel degrees
into specific gravity, all one has to do is to. multiply the pounds
per barrel by 2'77 or divide by -36 and add 1000.
Example :
1025 specific gravity - 1000 = 25 x "36 = 9 Ibs. per barrel.
1025 -1003 = 25-2-77 = 9
9 Ibs. per barrel x. 2'77 + 1000 = 1025 specific gravity.
9 -r "36 = 25 + 1000 = 1025
Although these instruments are essential in practical operations,
they are of little use in analytical work ; a pint of liquid is
necessary in order to immerse the instrument, and not only is
such a quantity seldom at hand in analytical operations, but
greater accuracy is necessary than these instruments are capable
of showing; hence in analytical operations the specific gravity
of a liquid is always ascertained by means of the specific-gravity
bottle.
Specific- Gravity Bottle. This instrument (fig. 36) consists of
a glass flask, generally made to contain some even quantity of
distilled water at 60 F. (15'5 C.), such as 25, 50, or 100 grams,
or 250, 500, or 1000 grains. An accurately ground stopper,
perforated by a fine hole, fits into the neck of the flask. The
liquid to be weighed is brought to the temperature of 60 F.
(15'5 C.), the bottle rinsed with it and then filled, and the stopper
fitted, care being taken to exclude air-bubbles. The bottle is
then wiped dry with a handkerchief, placed on the balance, and
weighed.
The object of the fine hole through the stopper is to allow for
QUALITATIVE AND QUANTITATIVE ANALYSIS Ii3
the expansion of the liquid which sometimes takes place owing
to the warmth of the atmosphere, or the hands when handling
the bottle. The position of the liquid
due to expansion thus finds its way
up the hole in the stopper, but pro-
vided the weighing be quickly per-
formed, the liquid on the top of the
stopper will not have had time to
evaporate before an exact weight is
obtained.
Before taking the specific gravity of
a liquid, we have first to ascertain the
weight of the bottle, both when empty
and when filled with distilled water, at FrG>
60 F. (15-5 C.); and knowing these
two factors, upon weighing any other liquid we obtain the specific
gravity by a single calculation.
Example :
Weight of bottle filled with wort . 90*960 grams.
Weight of empty bottle . . .21-810 ,,
Weight of wort . . 69*150
Weight of bottle filled with water . 86'260
Weight of empty bottle . . . 21 '8 10
Weight of equal volume of water to
that of wort . . . . 64*450
Wort 69-150 irw , fto
= 1072-92 specific gravity of wort.
Water 64-450
The specific-gravity bottle is usually purchased enclosed in a
tin box, the lid, which is arranged to hold a small weight, usually
containing shot (fig. 36). This weight is a counterpoise for the
weight of the empty bottle, so that in the above example the
specific- gravity bottle, filled with wort and placed upon the
balance, the counterpoise being placed upon the opposite scale
pan, would weigh 69*150 grams, which, divided by the weight of
water (64*450 grams), which has been previously ascertained and
noted so as to save a fresh calculation at each weighing, gives the
specific gravity. On the other hand, the specific-gravity bottle
may be purchased with a counterpoise, and to contain an exact
quantity of liquid such as 100 grams at 60 F. (15'5 C.), the
o
34
THE BREWER S ANALYST
weight of any liquid ascertained by its aid and in the manner
directed being, in such case, the specific gravity without any
calculation. Specific - gravity bottles, however, as purchased,
seldom contain exact quantities ; they are nevertheless at times
only slightly out, and in such cases, taking it that a bottle when
full contains 100*012 grams, with care the stopper may be
made smaller by rubbing with fine emery cloth, so as to fit
further into the bottle and the bottle thus made to hold exactly
100 grams. In like manner, if the bottle is found to contain
less than 100 grams, say
for instance 99*997, the
bottom of the stopper may
be slightly rubbed away
with emery cloth so as to
allow the extra volume to
be retained in the bottle
when the stopper is fitted.
29. The Centrifuge.
This instrument, more
commonly known as the
centrifugal machine (figs.
37, 38), has for many years
been employed by medical
men for the examination
of blood and urine, by
analysts for bacteriological,
microscopical, and other
purposes, and particularly
for testing milk.
It is employed in the brewer's laboratory for the rapid separa-
tion of suspended matter in beer.
The instrument (fig. 37) consists of an upright, which can be
clamped on to a table, with four short arms, which can be rotated
at extreme velocity by turning the toothed wheel communicating
with the screw of the upright. At the end of each arm hangs
a metal test-tube, into which slides a glass test-tube holding the
beer. When the machine is operated, the pendent tubes rise
towards the horizontal position, and the suspended matter in the
beer is driven in a compact mass by centrifugal force to the end
of the tube. It can then be examined microscopically, biologically,
and chemically.
Another form of the instrument is that shown in fig. 38. The
test-tubes are closed and placed round the dish in a horizontal
FIG. 37.
QUALITATIVE AND QUANTITATIVE ANALYSIS
35
position ; the lid is then lowered, and the dish rapidly revolved
by means of the strap or a piece of string.
With turbid beers it is often of great importance to know at
once the nature of the matter causing the cloudiness. Without
the centrifuge it is necessary to allow the suspended bodies to sub-
side which not only takes time, but may then be incomplete
or we may hasten subsidence by "forcing." Forcing, however,
brings about changes other than the mechanical separation of
FIG. 38.
suspended bodies, and these are not always required. Where,
therefore, it is desired to separate the suspended matter from
beers other than by fermentation and putrefactive changes which
are induced by forcing, the centrifuge becomes of value, and
enables us to gain information as to the nature of the organised
and amorphous matters suspended in the beer. Two or three
minutes' rotation of the apparatus is usually sufficient for the
purpose, but with very stubborn beers (such as those containing
budding primary yeast) a slightly longer time is often necessary.
It was shown by H. Tikes l seven years ago that micro-organisms
1 Allgem. Zeitschr. Bierbrau. und Malzfabrik., 1900, 28, 1-2.
36 THE BREWER'S ANALYST
can be rapidly separated from beer and other liquids by means of
the centrifuge, and it is due to him that the instrument has
become a valuable adjunct to the brewer's laboratory.
Sterilised solutions containing equivalent amounts of potash
alum and sodium carbonate were prepared, and a snail quantity
of each added to the liquid to be treated. After the evolution of
the carbon dioxide the mixture was spun in a centrifuge until the
gelatinous precipitate collected at the bottom of the tube.
The supernatant liquid was then poured off and the precipitated
alumina was then dissolved in 1 c.c. caustic soda, which had
practically no effect on the bacteria present, and the solution
examined under the microscope. By this process it was possible
FIG. 39.
to remove 89-90 per cent, of the organisms from beer and 96-100
per cent, of added organisms from water.
30. The Tintometer. This well-known instrument (fig. 39)
consists of a binocular tube B, terminating at the object end H
in two small square holes. The instrument is arranged to be
raised or lowered on the stand A and fixed in position as shown,
A 3 . At F a square of opaque unglazed porcelain is fixed.
Supplied with the instrument for brewers' purposes are two cells
or metal boxes, fitted at opposite sides with glass, one being
known as the 1-inch cell, the other the J-inch cell. A sample of
beer, caramel, sugar, or other solution to be tested is placed in
one of the cells, and the cell is then placed in position on the left
side of the instrument H. Upon looking through the tube at C
the colour of the solution is distinctly seen, and 'the object now is
to match the colour. For this purpose a series of yellow glasses,
known as the 52 series, are supplied with the instrument. These
glasses range from a decimal or from 1 degree in equal gradation
QUALITATIVE AND QUANTITATIVE ANALYSIS 37
up to any desired number. For instance, glass number 2 is of
double the colour intensity of glass number 1, or glasses numbered
4 and 6 equal in intensity the colour glass number 10. These
glasses are taken and slipped into the instrument at J, so that
upon looking through the tube at C the colour of both the
glasses and the solution are viewed, the glasses being added until
the colour of the solution is matched.
The numbers of the glasses are then read and added together,
and the colour value expressed as of so many degrees. For example,
if glasses 8, 11, and 12 were required to match the colour of the
solution in a 1-inch cell, the colour would be registered as equal to
31 in 1' cell. The author carried out a series of experiments
with this instrument in 1888, almost as soon as it was introduced,
and may here, with slight alteration, repeat the same as then
published. 1
.... The colour of beer is of great importance, since
uniformity in this direction is greatly admired by most consumers.
In order, therefore, to turn out beers day by day of constant
colour uniformity in accordance with their respective quality, some
form of instrument is useful, and we here refer to Lovibond's
Tintometer.
This instrument answers a chain of questions which are
interesting and necessary to the brewer, beginning with the
colour of a percentage solution of malt in relation to that of the
worts before and after boiling, to the registration of the colour of
the beer. A few estimations of colour in malt will lead to a
practical knowledge of character and evenness in drying ; it will
soon be ascertained what colour in malt produces a given colour
in ale, and what quantity of black malt or caramel is required to
produce a beer of definite colour intensity. Experiments carried
out with the tintometer were as follows :
Degrees of Colour.
1-inch cell.
Pale malt, 5 per cent, solution . . . .3
Wort before boiling, 1050 specific gravity . .10
Wort after boiling . . . . . .14
Finished beer .... . 13
Finished beer after storing 3 weeks . . .11
The above are the observations of an actual brewing, the
ultimate eleven degrees of colour being about that of the Burton
pale ale.
The instrument is also of great value in estimating roasted
1 Brewers' Guardian, Feb. 21, 1888.
38 THE BREWER'S ANALYST
malts and caramels, where the value bought is primarily colour,
the variations between samples very similar in outward judgment
being sometimes very wide :
Roasted Malt.
Degrees of Colour.
No. 1. Black, 1 per cent, solution J thickness 1\
No. 2. Chocolate, ,, 10
These observations show the large difference in colour value
between two samples of which the difference in price was very
trifling.
PART II.
THE POLARIMETER.
POLARISATION OF LIGHT SPECIFIC ROTATORY POWER SOLUTION
WEIGHT AND SOLUTION FACTORS CUPRIC OXIDE REDUCING
POWER.
SOME twenty years ago the Polarimeter, or " Polariscope " as it
was then incorrectly called, was looked upon and described by
those who had but little, if any, knowledge of its use, as a
" pretty but useless chemical toy." With the rapid strides that
have since been made in the science of brewing, the polarimeter
has become an indispensable instrument, and has played a
wonderful part in enabling those who have worked upon starch-
conversion products to define many points, particularly with
regard to the composition of the so-called malto-dextrins.
That the polarimeter is a most useful apparatus to the brewer,
and one which, without any laborious or tedious experimenting,
enables him to estimate the conversion products of his mashes,
apart from its value in numerous other well-known directions, is
now a recognised fact. As, therefore, it is essential that the
modern brewer should become familiar with the instrument, it is
necessary that we sketch the principle upon which it is based,
and then describe its construction.
The principle of the instrument depends upon the polarisation
of light.
Polarisation Of Light. There are four processes by means
of which a ray of light may be polarised : these are reflexion,
ordinary refraction, double refraction, and scattering by small
particles.
It will be convenient, however, to reproduce the description of
the phenomena of polarisation as given by Spottiswoode, 1 who
1 Polarisation of Light, Macmillan & Co.
39
40 THE BREWER'S ANALYST
starts with a plate of crystal called tourmalin as an instrument,
tolerably simple in its action and easy of manipulation :
"Tourmalin is a crystal, of which there are several varieties,
differing only in colour. Very dark specimens generally answer
the purpose well, excepting that it is difficult to cu'u them thin
enough to transmit much light. Red, brown, or green specimens
are usually employed ; the blue are, for the most part, optically
unsuitable. Some white, or nearly white, specimens are very
good, and may be cut into thicker plates without loss of
light.
" If we take a plate of tourmalin, cut parallel to a particular
direction within the crystal called the optic axis, and interpose it
in the path of a beam of light at right angles to the direction of
the beam, the only effect perceptible to the unassisted eye will
be a slight colouring of the light after transmission, in conse-
quence of the natural tint of the particular piece of crystal.
But if we examine the transmitted beam by a second similar
plate of tourmalin placed parallel to the former, the following
effects will be observed : When the two plates are similarly
placed, i.e. as if they formed one and the same block of crystal,
or, as it is technically expressed, with their optic axes parallel,
we shall perceive only, as before, the colouring of the light due
to the tints of the two plates. But if either of the plates be then
turned round in its own plane so as always to remain perpen-
dicular to the beam, the light will be observed to fade gradually
until, when the moving plate has been turned through a right
angle, the light becomes completely extinguished. If the turning
be continued beyond the right angle, the light will begin to
revive ; and when a second right angle has been completed, the
light will be as bright as at the outset. In figs. 40 and 41, a, b,
c -> d, e, j\ g, h represent the two plates. In fig. 40 the two plates
are supposed to be in the first position ; in fig. 41 the plate e, /,
g, h has been turned through a right angle.
" Of the parts which overlap, the shading in fig. 40 represents
THE POLARIMETER 41
the deepened colour due to the double thickness of the crystal ;
in fig. 41 it indicates the complete extinction of the light. The
same alternation of brightness and extinction will continue for
every right angle through which the moving plate is turned.
Now it is to be observed that this alternation depends only upon
the angle through which one of the crystals has been turned, or,
as it is usually stated, upon the relative angular position of the
two crystals. Either of them may be turned, and in either
direction, and the same sequence of effect will always be produced.
But if the pair of plates be turned round bodily together, no
change in the brightness of the light will be made. It follows,
therefore, that a ray of ordinary light possesses the same properties
all round ; or, as it may be described in more technical language,
a ray of ordinary light is symmetrical in respect of its properties
about its own direction. On the other hand, a ray of light, after
traversing a plate of tourmalin, has properties similar, it is true,
on sides or in directions diametrically opposite to one another,
but dissimilar on intermediate sides or directions. The properties
in question vary, in fact, from one angular direction to another,
and pass through all their phases, or an entire period, in every
angle of 180. This directional character of the properties of the
ray, on account of its analogy to the directional character of a
magnet or an electric current, suggested the idea of polarity j and
hence the condition in which the ray was found to be was called
polarisation.
"Having so far anticipated the regular order of things on the
experimental side of the subject, it will be worth while to make a
similar anticipation on the side of theory. It is considered as
established that light is due to the vibrations of an elastic
medium, which, in the absence of any better name, is called ether.
The ether is understood to pervade all space and all matter,
although its motions are affected in different ways by the mole-
cules of the various media which it permeates. The vibrations
producing the sensation of light take place in planes perpendicular
to the direction of the ray. The paths or orbits of the various
vibrating ethereal molecules may be of any form consistent with
the mechanical constitution of the ether ; but, on the suppositions
usually made, and none simpler have been suggested, the only
forms possible are the straight line, the circle, and the ellipse.
But in ordinary light the orbits at different points of the ray are
not all similarly situated ; and although there is reason to believe
that in general the orbits of a considerable number of consecutive
molecules may be similarly situated, yet in a finite portion of the
42
THE BREWER'S ANALYST
ray there are a sufficient number of variations of situation to
prevent any preponderance of average direction.
" This being assumed, the process of polarisation is understood
to be the bringing of all the orbits throughout the entire ray
into similar positions. And in the case of the tourmalin plate
the orbits are all reduced to straight lines, which consequently
lie in one and the same plane. For this reason the polarisation
produced by tourmalin, as well as by most other crystals, is
called rectilinear, or, more commonly, plane polarisation. This
property of tourmalin may also be expressed by saying that it
permits only rectilinear vibrations parallel to a particular
direction, determined by its own internal structure, to traverse it.
" Adopting this view of polarisation as effected by a plate of
tourmalin, it would be interesting to ascertain the exact direction
of the vibrations. And a simple experiment will go far to satisfy
a
o n
FIG. 42.
us on that point. The argument, as now stated at least, is
perhaps based upon general considerations rather than upon
strict mechanical proof; but the experimental evidence is so
strong that it should not be denied a place here. Suppose for a
moment that the tourmalin be so placed that the direction
of vibration lies either in or perpendicular to the plane of
incidence (that is, the plane containing the incident ray, and
perpendicular to the surface on which it falls at the point of
incidence) ; then it is natural to expect that vibrations executed
in the plane of incidence will be far more affected by a change
in the angle of incidence than those perpendicular to that plane.
In fact, the angle between the direction of the vibrations and the
surface upon which they impinge will in the first case vary with
the angle of incidence, but in the second case it will remain
unchanged. In fig. 42, n o represents the ray of light ; the
arrow the direction of vibration ; a, b, c, d, a', t/, c, d' the plate
in two positions, turned in the first instance about the direction
of vibration, in the second about a line perpendicular to it.
"Dismissing, then, the former supposition, and supposing that
nothing whatever is known about the direction of vibration, then,
THE POLARIMETER 43
if all possible directions be taken in succession as pivots about
which to tilt or turn the second tourmalin, it will be found that
for one direction the intensity of the light diminishes more
rapidly with an increase of tilting (or, what is the same thing,
with an increase of the angle of incidence) than for any other.
And, further, that for a direction at right angles to the first, the
intensity of light diminishes less than for any other, while for
intermediate directions the diminution of intensity is intermediate
to those above mentioned. In accordance, therefore, with what
was said before, we may conclude that the vibrations are parallel
to the line or pivot about which the plate was turned when the
diminution of light was least.
" Secondly, polarisation may be effected by reflexion. If light
reflected from the surface of almost any, except metallic, bodies
be examined with a plate of tourmalin, it will in general be found
to show traces of polarisation ; that is to say, if the plate of
tourmalin is caused to revolve in its own plane, and the reflected
rays be viewed through it, then in certain positions of the plate
the reflected light will appear less bright than in others. If the
angle at which the original rays fall upon the reflecting surface
be varied, it will be found that the amount of alteration in
brightness of the light seen through the revolving tourmalin (or
analyser) will also vary. This fact may also be expressed thus :
In polarisation by reflexion, the degree of polarisation, or the
amount of polarised light in the reflected rays, varies with the
angle of incidence on the reflecting surface. But at a particular
angle, called on that account the polarising angle, the polarisation
will be a maximum. This angle (usually measured between the
incident ray and perpendicular to the reflecting surface) is not
the same for all substances ; in fact, it varies with their refractive
power according to a peculiar law, which may be thus enunciated :
The tangent of the polarising angle is equal to the refractive
index. Simple geometrical considerations, combined with the
usual expressions for the laws of reflexion and refraction, will
show that this relation between the polarising angle and the
refractive index may be also expressed in the following way : If
light be incident at the polarising angle, the reflected and refracted
rays will be at right angles to one another.
"In fig. 43, si represents the incident, if the reflected, and in
the refracted ray. Then si will be incident at the polarising
angle when the angle fin is a right angle.
" An apparatus devised by Tyndall for experimentally demon-
strating the laws of reflexion and refraction is admirably adapted
44
THE BREWER'S ANALYST
for verifying this law. The following description is quoted from
his Lectures on Light : ' A shallow circular vessel RIG (fig. 44),
with a glass face, half filled with water rendered barely turbid
by the admixture of a little milk or the precipitation of a little
mastic, is placed upon its edge, with its glass face vertical. By
means of a small plane reflector M, and through a slit I in the
hoop surrounding the vessel, a beam of light is admitted in any
required direction.'
" If a little smoke be thrown into the space above the water,
the paths of the incident, the reflected, and the refracted beams
will all be visible. If, then, the direction of the incident beam
be so adjusted that the reflected and the refracted beams are at
right angles to one another, and a NicoPs prism be interposed in
FIG. 43.
the path of the incident beam, it will be found that, by bringing
the vibrations alternately into and perpendicular to the plane of
incidence, we shall render the intensity of the reflected and
refracted rays alternately a minimum.
" Thus much for the verification of the law. But not only so ;
if we take different fluids, and for each of them in succession
adjust the incident beam in the same manner, we shall only have
to read off the angle of incidence in order to ascertain the
polarising angle of the fluid under examination.
" The general theory of the reflexion and refraction of polarised
light was first established by Fresnel, who based it upon the four
following suppositions :
" (1) That the ether, to the vibrations of which light is supposed
to be due, is regarded as perfectly elastic, so that the whole of
the motion taking place at the source of light is transmitted
without loss throughout the ray. This appears to be substantially
THE POLAKIMETER 45
true in transparent media; but in proportion as a substance is
more opaque, so do its molecules take up part of the motion of
the ether, and convert the light into heat (the principle of vis
viva).
" (2) That in passing from one medium to another, although the
velocity and extent of the motion may change, yet its character
is not altered (the principle of continuity).
" (3) That any change in velocity or in extent, due to the
passage from one medium to another, takes place immediately at
the surface of separation ; and that such change is maintained
subsequently.
" (4) That while the elasticity of the ether in different bodies re-
mains the same, its density may differ.
" By means of these ^ ,,
suppositions relations
were established be-
tween the intensity of
the reflected and re-
fracted rays on the one
hand, and the angles of
reflexion and refraction
on the other, from which
many phenomena pre-
viously known only as
experimental facts were
deduced as conse-
quences. Of these, one FIG. 44.
should be mentioned,
viz., that in the case of vibrations in the plane of incidence, if
the ray be incident at such an angle that the reflected and
refracted rays are perpendicular to one another, there can be no
reflected ray.
" We next come to the subject of polarisation by double
refraction.
"There are a large number of crystals which have the property
of generally dividing every ray which passes through them into
two. But the extent of separation of the two rays varies with
the direction of the incident ray in reference to the natural
figure of the crystal. In every double refracting crystal there
is at least one, and in many there are two, directions in which
no separation takes place. These directions are called optic axes.
" Of such crystals Iceland spar (crystallised carbonate of lime)
is the most notable instance. If we take a block of such spar
46
THE BREWERS ANALYST
split into its natural shape, a rhombohedron, fig. 45, and for
convenience cut off the blunt angles by planes perpendicular to
the line joining them, ab, it will be seen that a ray of light
transmitted perpendicularly to these planes, that is, parallel to
the line joining the blunt angles, is not divided. In fact, the
image of an object seen by the eye in the direction in question
appears single, as if passed through a block of glass. The
direction in question (viz. the line a b itself, and all lines passing
through any part of the crystal parallel to a b) is called the optic
axis of the crystal.
"If, however, the crystal be tilted out of this position in any
direction, it will be seen, by the appearance of two images instead
of one, that the rays are divided into two. The angular diver-
gence of the two sets of rays, or, what comes to the same thing,
the separation of the two images, depends upon the angle through
FIG. 45.
which the crystal has been turned ; or, as it may also be expressed,
upon the angle between the directions of the incident ray and the
optic axis of the crystal. When this angle amounts to a right
angle the separation is at its greatest; and if the crystal be
still further turned, the images begin to come together again
until, when it has turned through another right angle, they
coincide.
" This process of separation, or doubling the rays, is called double
refraction, and the character of the polarisation of two images is
best studied by using flat instead of curved surfaces for separating
the rays.
"For the purpose in question there is, perhaps, no better
instrument than the double-image prism. This consists of a
combination of two prisms, one of Iceland spar, so cut that
the optic axis is parallel to the refracting edge; the other of
glass, and usually having a refracting angle equal to that of
the spar.
" The rays passing through the crystal prism being perpendicu-
THE POLARIMETER
47
lar to the optic axis, undergo the greatest separation possible.
And the chromatic dispersion caused by that prism is usually
corrected or neutralised entirely in the case of the extraordinary,
and nearly so in that of the ordinary, ray by the glass prism,
which is placed in a reverse position. In this arrangement the
extraordinary image occupies the centre of the field, and remains
fixed when the double-image prism is made to revolve in a plane
perpendicular to the incident rays ; while the ordinary image is
diverted to a distance from the centre, and revolves in a circle
about that centre when the prism revolves.
" Other dispositions of the double-image prism are also made for
particular purposes ; e.g. in which neither image is central, and in
which the chromatic dispersion of both images is partially
corrected. If the nature of the light in the two images thus
formed be examined by any polarising instrument,
it will be found that it is polarised in both cases,
and that the vibrations in the one image are
always perpendicular to those in the other. And
in particular, the vibrations in the extraordinary
image are parallel and those in the ordinary are ,,
perpendicular to the optic axis.
" On these principles polarising and analysing
instruments have been constructed by various
combinations of wedges or prisms of Iceland spar,
the details of which it is not necessary to describe
in full. But the general problem and object pro-
posed in all of them has been to cause such a
separation of ordinary and extraordinary rays that
one set of rays may, by reflexion or other methods, be further
diverted, and afterwards thrown altogether out of the field of
view. This done, we have a single beam of completely polarised
light, and a single image produced from it.
" One such instrument, however, the Nicol's prism, named after
its inventor, a clever optician, on account of its great utility and
its very extensive use, and which is to be found in all polarimeters,
must be described. A rhombohedron of Iceland spar, double of
its natural length, is taken (fig. 46) ; and one of its terminal faces
P, which naturally makes an angle of 71 with the blunt edges
K, is cut off obliquely so as to give the new face, say P', an
inclination of 68 to the edges K. The whole block is then
divided into two by a cut through the angle E in a direction at
right angles to the new face P'; the faces of this cut are then
carefully polished, and cemented together again in their original
FIG. 46.
48
THE BREWER'S ANALYST
position with Canada balsam. Fig. 47 represents a section of
such a prism made by a plane passing through the edges K. A
ray entering as a b is divided into two, viz. b c the ordinary and
b d the extraordinary. But the refractive index of the Canada
a balsam is 1 '54, i.e. intermediate between that of
the spar for the ordinary (1'65) and the extra-
ordinary (the minimum value of which is 1'48)
rays respectively; and in virtue of this the
ordinary ray undergoes total reflexion at the
surface of the balsam, while the extraordinary
passes through and emerges ultimately parallel
to the incident ray. Fig. 48 shows an end view
of a Nicol's prism P P, representing the plane of
polarisation of the emergent polarised ray.
"Two such instruments, wheri used together,
are respectively called the " polariser " and the
"analyser," on account of the purposes to which
they are put. These, when placed in the path
of a beam of light, give rise to the following
phenomena, which are, in fact, merely repro-
ductions in a simplified form of what has
gone before.
" When polariser and analyser are placed in front of one another
with their shorter diagonals parallel, that is, when the vibrations
in the image transmitted by the one are parallel to those in the
image transmitted by the other, the light will be projected exactly
as if only one instrument existed. If, however, one instrument,
say the analyser, be turned round,
the light will be seen to fade in
the same way as in the case of the
tourmalin plates; until, when it has
been turned through a right angle,
or, as it is usually expressed, when
the polariser and analyser are crossed,
the light is totally extinguished.
" In the complete apparatus or
polarimeter we may incorporate any system of lenses, so that we
may make use of either parallel or convergent light, and finally
focus the image produced."
Now various substances have the property of rotating polarised
light, as, for example, turpentine and sugar solutions of various
kinds, such as dextrin, maltose, dextrose, etc. If, therefore, we fill
a glass tube with turpentine or with a certain percentage sugar
FIG. 48.
THE POLARIMETER 49
solution, place the tube in the polarimeter and then look through
the telescope, it will be noticed that the two halves of the field
are unequally illuminated, being darker on one side than on the
other. By now adjusting the instrument so that both halves of
the field are evenly illuminated, the exact angle of rotation can
be read off from the vernier scale. Of the various substances
which are optically active, some turn the polarised ray to the
right, and are known as right-handed, dextro-rotatory, or positive
substances, whilst others bend the ray to the left, and are known
as left-handed, levo-rotatory, or negative bodies; the signs +
and - being used to briefly designate each kind. All solutions
of an optically active substance of the same strength, when tra-
versed by the polarised ray in layers of the same thickness, rotate
the ray, each substance having a definite power. When this is
calculated upon a certain definite strength of solution, and upon
a layer of such solution of a definite thickness, an expression is
found which is termed the "specific rotatory power" or the
"opticity"of the substance. The function, then, of the polari-
meter is to determine the amount of rotation which the polarised
ray suffers in passing through a layer of the solution of an
optically active substance.
From this, by taking certain other factors into account, the
specific rotatory power of the substance can be found ; and when
the specific rotatory power of a substance present in solution is
known, the polarimeter enables us to estimate its amount.
It is not within the scope of this work to describe the subject
at greater length ; suffice it to say that the polarisation of light is
undoubtedly one of the most intricate but at the same time most
beautiful branches of the science of optics. For full information
the reader should consult the latest work, viz. The Optical Rota-
tion of Organic Substances, by Professor Landolt. 1
The Polarimeter. There are several differently constructed
polarimeters, such as the Soleil or Ventzke-Scheibler ; the Lippich ;
Laurent; Schmidt & Haensch Half -Shadow instrument, and
others ; but the two most commonly used forms are the Laurent
and Schmidt & Haensch Half-Shadow. With the latter a white
light illumination from oil or gas is employed, but with the
former a sodium flame illumination is used.
Specific rotatory power, as determined in reference to the D
ray of the solar spectrum (that is, with the sodium flame), is
indicated by [a] D , whilst when determined by the older forms
1 Translated from the German by Dr Long. The Chemical Publishing Co..
Easton, Pennsylvania.
4
50
THE BREWER'S ANALYST
of instrument, such as the Ventzke-Scheibler, it is indicated
by [a],
In the Laurent polarimeter which is shown, fig. 49, F
indicates the telescope, I I the magnifying glasses, n n the two
verniers, K the graduated dial, A a prism of Iceland spar known
as the " analyser," or analysing Nicol, which is fixed to the revol-
ving dial K and to the telescope, and capable of being rotated on
its axis by means of the milled head T seen underneath it. It
carries with it the two verniers n n, which indicate the observed
rotation on the scale of the dial-plate K.
FIG. 49.
Next comes the trough B E, with a lid, in which the tube
50) filled with the solution to be examined is placed.
P is the movable " polariser " (another prism of Iceland spar;),
which converts one half of the ordinary light passing through;jl
into polarised light, the other half being reflected to the side aflfl'
absorbed. Above it is a fixed graduated segment of a circle h. At
G is a thin plate of quartz, covering half the field, known 'as
Laurent's plate, its function being to increase the delicacy of^jtfre
indications of the instrument, and at S is placed a bichromate
plate.
The apparatus can only be used in conjunction with a sodium
THE POLARIMETER 51
flame, and a suitable sodium lamp is supplied with it. This con-
sists of a burner supplied with a small piece of platinum wire, on
which some pulverised chloride of sodium is placed and made
intensely incandescent by means of the non-luminous flame from
the burner ; the apparatus is pointed to the most intense part of
the yellow flame, which can be done easily by means of an
adjuster with which the lamp is provided.
The lamp is placed a few inches away from the end of the
telescope, and observations are taken in a darkened room or
cupboard.
The observation tubes (fig. 50) are made of glass, their ends
being ground perfectly true. A brass cap attached to each end
enables the tubes to be closed water-tight with small circular
glass plates, which are retained in position by the screw-caps.
The length of the tubes usually employed are 1 and 2 decimetres
(100 and 200 millimetres) ; an extra 2-decimetre tube, jacketed for
invert-sugar determinations, being very useful.
FIG. 50.
If the liquid to be examined is dark in colour, a decimetre
(100 mm.) tube is used; whilst if sufficiently pale a 2-decimetre
(200 mm.) tube is employed by preference, since the longer the
tube the larger the reading and the smaller the chance of error.
It becomes necessary, however, in some instances to decolorise a
solution before it is possible to take a reading. Decolorisation is
usually effected by either passing the solution repeatedly through
animal charcoal or by adding basic lead acetate solution and
then filtering : examples are given hereafter.
In using the instrument, the lamp is lighted and the flame
adjusted to position. On looking through the eye-piece a circle
of light is seen divided into two halves by a vertical line, and both
halves of the field of view should be exactly equally illuminated.
For this purpose the telescope F is, by drawing it out or pushing
it together, focussed on the Laurent plate. If the graduated dial
is now turned round 3 or 4 degrees to the right of the zero line
it will be seen that one half of the field of view will become
lighter, the other half darker. The same will be observed on
turning it round to the left. That position, however, exactly
between these, when both halves of the field of view are equally
illuminated, is the zero position of the instrument, and the
52 THE BREWER'S ANALYST
latter is first so adjusted that the zero line of the circle
coincides with the zero line on the vernier. The half-shadow
can now be made lighter or darker, according as the polariser
is turned more or less to the right or left of the zero line,
by means of the pointer reaching beyond the dial-segment.
When the pointer is in the zero position the Laurent's plate
and the polarising Nicol have the same wave direction, and
consequently, if at the same time the analyser is placed in the
zero position, both halves of the field of view appear black. The
nearer the pointer is to the zero line, the darker the half-shadow
will be, and the more sensitive the apparatus ; but when the
solution being examined is not quite transparent, the pointer
must be moved more or less away from the zero line, so that the
field of view is clear. For the majority of experiments the
position of the pointer at 7 J is most suitable ; the apparatus is
therefore usually so adjusted that in this position the dial and
vernier read exactly 0. When the pointer is moved, of course,
the zero point of the apparatus changes and no longer corresponds
with the zero line of the dial. The difference between the latter
and the zero position of the apparatus must either be taken into
account this is the most simple way or else, after the graduated
dial has been moved to 0, the apparatus must be again placed in
the zero position ; to do this, the analysing Nicol is turned by
means of the screw T so far to the right or left until both half-
shadows are equal.
Having adjusted the instrument, if we now take a 2-decimetre
(200 mm.) observation tube, fill it with a 10 per cent, solution
of cane-sugar and place it in the instrument, it will be found on
examination that both halves of the Held of view are unequally
illuminated. On turning the index by means of the milled-head
in the same direction as that in which the hands of a clock move
( + ), a position will be reached when both halves of the field are
equally illuminated. When this position is reached, the reading
of the scale indicates exactly the amount of twisting or rotation
which the polarised beam of light has undergone in passing
through a layer of 10 per cent, cane-sugar solution 2 decimetres
(200 mm.) thick; and from this can be deduced the specific
rotatory power or opticity of the solution as before mentioned.
It often happens, especially during the time when the apparatus
is first taken in use, that a circumstance is mistaken for the zero
position of the apparatus which arises when the circle has been
turned too far and has gone beyond the sensitive range. In this
case the light is also to a certain extent equal, but will hardly
THE POLARIMETER
53
change if the circle is turned round 10, 15 or even more degrees.
Special attention must, therefore, be given to this circumstance,
especially after the fluid Jias been filled into the tube and the
latter placed in the apparatus, that a sudden change of light and
dark is not to be observed in both halves of the field of view
when, as described, the circle is turned a few degrees either to the
right or to the left of the zero line. When the tube has been
placed in the apparatus, the first thing to do is to again adjust
FIG. 51.
the telescope exactly, so that the field of view is again clear and
divided into two halves by the vertical line ; then the circle is
turned round until the half-shadows on both halves are the
same, and the result is then read off the scale on the circle.
The graduated dial is graduated right round, that is, into 360
degrees, and, by means of the vernier attached to the index, can
be read to the sixtieth of a degree.
The Lippich polarimeter shown (fig. 51) is somewhat similar
in construction to the Laurent just described, excepting that a
bichromate solution is employed instead of the bichromate glass.
54 THE BREWER'S ANALYST
With the Schmidt and Haensch Half-shadow Polari
HieteP. The scale is entirely different from that of the Laurent.
As the instrument was constructed specially for the use of
sugar manufacturers and refiners, its scale is constructed so as to
show percentages of cane-sugar directly. It has consequently 100
divisions, which by means of the vernier can be read to tenths of
a division. When the 2-decimetre tube is filled with a solution,
100 c.c. of which contains 26*048 grams of pure cane-sugar, the
instrument indicates 100 scale divisions. If an impure sugar is
employed for making the solution, and with this the reading is
75 '8 divisions, then such a sample contains only 75 '8 per cent, of
cane-sugar. Owing to this difference in the scales of the two
instruments, it is necessary, in order to convert half-shadow
degrees into Laurent degrees, to multiply by a factor. The
divisions of the scale of the instrument bear a fixed relation,
however, to the degrees of a sodium-light or Laurent polarimeter.
Each single division is equal to 0'34f>9 of a degree of the Laurent
instrument for the ordinary carbohydrates, excepting cane-sugar,
for which each division of the scale is equal to 0'3469 of a
degree. When therefore the half-shadow instrument is employed
to determine the specific rotation of a carbohydrate, multiply by
0*3459 for all carbohydrates other than cane-sugar, in order to
convert the observed scale divisions into angular degrees for
sodium light; in the case of cane-sugar multiply by 0*3469.
In order to convert divisions of the half-shadow instrument
into degrees [a]j, multiply by 0*3843 for all carbohydrates
other than cane-sugar; in the case of cane-sugar, multiply by
0*3854.
Lastly, the phenomenon of " mutarotation " or " bi-rotation "
must be mentioned ; that is to say, the varying opticity of certain
solutions. For instance, freshly prepared solutions of invert-
sugar or maltose show abnormal rotation; in the former
solution the rotation being above, in the latter below, normal.
In either case the solution may be immediately rendered normal
by either the addition of a very small amount of alkali (0*1 per
cent.) or by boiling. Care must be taken not to overlook this
point when analysing worts or freshly prepared solutions con-
taining maltose, dextrose, or levulose. 1 Observations should
also always be made with the solution to be examined at a
definite temperature, 68 F. (20 C.) being most usually
employed.
1 For recent views concerning muta rotation, see H. E. Armstrong,
"Studies on Enzyme Action," Jnl. Chem. &oc., 1903, Ixxxiii., 1310.
THE POLARIMETER 55
SPECIFIC lioTATORY POWER OR OPTICITY.
By the above terms is meant the angle indicated by the
polarimeter when a layer of the substance, 1 decimetre (100
mm.) in thickness, is examined in that instrument. For instance,
when a decimetre tube is filled with turpentine and examined on
the Laurent polarimeter, the reading is 22'4 ; this number, divided
by the specific gravity of the turpentine, gives directly the specific
rotatory power of that particular turpentine.
The specific rotatory power of an optically active substance in
solution is denned as the angle through which a plane polarised
ray of light of definite refrangibility is rotated by a column of
liquid, 1 decimetre in length, containing 1 gram of the sub-
stance in 1 c.c.
It is obvious that a 100 per cent, solution chus indicated could
not be used, and we therefore employ a 10, 20, or other per cent,
solution, and calculate to 100 per cent. If, for instance, a 10
per cent, solution of pure cane-sugar be examined in a 1-deci-
metre tube, the angle observed will be 6*66, and the multiplication
of this figure by 10 will give the opticity of cane-sugar = 66'6.
If instead of a 10 per cent, solution, one of 20 per cent, is
employed, the angle observed will be twice as large, and will,
consequently, have to be halved before being multiplied by 10.
Should the 2-decimetre (200 mm.) tube be employed, then
the reading will have to be halved and multiplied by 5. The
opticity is obtained in any case by the following equation :
R
T
Lx Too
in which R is the reading of the polarimeter, L the length of the
tube employed in decimetres, and G the number of grams
of substance contained in every 100 c.c. of the solution.
For instance, suppose we have a solution containing in every
100 c.c. 13'5 grams of a body, the opticity of which we wish to
determine, and upon examining in the 2 decimetre tube we
obtain a reading of + 42*5", then
The opticity or specific rotatory power of such a solution is
therefore [a] D = +157*4.
56 THE BREWER'S ANALYST
When the specific rotatory power of a solution is known, the
quantity of that substance in solution is readily determined with
the polarimeter by the aid of the following formula :
G is the number of grams of the substance in 100 c.c. of solu-
tion, R the observed angle, and [a] D the opticity of the substance,
L being the length of the observation tube in decimetres.
For example, a solution of cane-sugar of unknown strength is
found to give a reading of + 18 '20, then
Every 100 c.c. of the solution, therefore, contains 13'66 grams
of cane-sugar.
Again, supposing we have a solution containing maltose and
dextrin, and we desire to ascertain the amount of each of these
bodies present in the solution. Knowing as we do the opticity
of maltose and of dextrin, we proceed thus :
The solution is found to contain, say, 15*5 grams per 100 c.c.
of the mixture of maltose (opticity [a] D + 13S), and dextrin
([a] D + 198'9). On examining the solution in a 2-decimetre
tube, the angle observed is +52'90. Then
J. -M.+170... .
2x TOO
From this number, which is the opticity of the mixed substances,
we have to subtract the opticity of that which has the less
rotatory power in this case it will be maltose 138 and divide
the result by the difference of the rotatory powers of the two
bodies, which here is 60'9 (198'9-138).
This will be 170-6-138 = 32-6, and ^ = 0'53 gram dextrin.
60'9
Each gram of substance in solution consists therefore of 0'53
gram of dextrin and 0"47 gram of maltose ; consequently the
15 '5 grams contain 8 '2 15 grams of dextrin and 7 '285 grams of
maltose.
Lastly, to convert degrees [a] D into [a] j5 multiply by 1-111 or
simply add one-ninth.
To convert degrees [a]j into [a] D , multiply by '9 or simply
deduct one-tenth.
THE POLARIMETER
57
The following are the specific rotatory powers of the carbo-
hydrates according to Brown, Morris, and Millar. 1
TABLE SHOWING THE SPECIFIC ROTOTARY POWERS OF THE
CARBOHYDRATES.
Substance.
Formula.
Specific rotatory
power (absolute).
Specific rotatory
power reduced to
the common
divisor 3 "86.
[*)
IXb
t a ]l3'86
E
Dextrin . . (C 12 H 20 10 ) n
+ 221
+ 198-9
+ 216
+ 194*
Cane-sugar . C^H^n
+ 73-8
+ 66-6
+ 74
+ 66-8
Maltose . . ,,
+ 153-3
+ 138
+ 151
+ 135-9
Lactose (anhyd. ) ,,
+ 61-6
+ 55'4
+ 59-6
+ 53-6
Lactose (cryst. ) . C^H^OnHoO
+ 58-5
+ 52'6
+ 56't)
+ 50-9
Dextrose .
C 6 H 12 6
+ 57
+ 51-3
+ 57-4
+ 517
Levulose .
-106
- 95-4
-104-1
- 937
at 15-5 C.
at 15 -5 C.
I n vert- sugar . C 6 H 12 6 +
- 24-5
- 22
- 24-4
- 21-9
C 6 H 12 6
at 15 '5 C.
at 15-5 C.
Iii this table it will be noticed that the absolute specific
rotatory power is given, as well as that reduced to the common
factor 3-86.
SOLUTION WEIGHT AND SOLUTION FACTORS.
In the analysis of the carbohydrates it is necessary in most
instances to know the amount of solid matter present in solution.
This may be estimated by evaporating a known bulk to dryness
and weighing the residue. Such method, however, is by no
means satisfactory, since it becomes essential, in order to remove
the last traces of moisture, to continue heating for a considerable
time, and by thus heating, the organic substance is to an extent
decomposed. On this account it was found preferable to ascertain
the amount of matter in solution by taking the specific gravity
and dividing the excess weight over water (1000) by a factor.
The original factor employed was 3 '85, which was devised by
O'Sullivan in 1876, 2 who based it on the assumption that 10
grams of pure maltose or pure dextrin, when dissolved in so much
water that the solution measures exactly 100 c.c. at a temperature
of 60 F. (15-5 C.), the specific gravity of the solution (10 per
cent.) is 1038 '5, water being taken as 1000.
l Jnl. Chem. Soc., Jan. 1897, 86.
2 Ibid., 1876, 129.
58 THE BREWER'S ANALYST
Assuming that the strength of such solutions was strictly
proportional to their specific gravity, a 1 per cent, solution would
have a specific gravity of 1003*85, and solutions containing inter-
mediate quantities would have gravities expressed by intermediate
values. Consequently, if each per cent, of either of these bodies
raised the specific gravity of a solution by 3'85, it would be a
simple matter to ascertain the amount present in solution ; it
would, in fact, be only necessary to subtract 1000 from the
specific gravity of the solution and divide the figure so obtained
by 3-85.
Thus 100 c.c. of a solution of maltose of a specific gravity of
1055 would contain
1055- 1000 =14 . 285 grams of that su bstance.
O'OO
Later on Brown and Heron 1 came to the conclusion that 3'85
was too low for maltose, the correct divisor being 3 '9 3 14, and
O'Sullivan afterwards gave the fresh divisor 3 '95 for starch
conversion products. It was afterwards found that with solutions
of the various carbohydrates the specific gravity of the solution
was not strictly proportional to the amount of the substance
contained in solution, and Brown and Heron 2 proposed the use
of 3 '86 in all cases as a solution divisor ; but this is only correct
for a 10 per cent, solution of cane-sugar, which has a specific
gravity of 1038*6 at 60 F. (15'5 C.).
Brown, Morris, and Millar 3 have made fresh determinations "of
the solution weights of a number of the sugars, and of various
starch transformation products ; the last traces of moisture being
removed from the substances dealt with by a process devised by
Lobry de Bruyn and Van Leent. It consists in placing the sugar
or other body in a small flask, which is placed in a water or oil
bath, and connected with another small flask containing anhydrous
phosphoric acid, a vacuum being maintained in the apparatus
during the drying process. From the results thus obtained, the
solution factor was determined for various concentrations. They
were found, as in the case of cane-sugar, not to be directly pro-
portional to the percentages present in solution, but might be
expressed in the form of a series of curves. These are given in
a table, and by consulting this the proper solution factor for any
concentration of any of the sugars given can be found by inspection.
The solution factors for solutions of several of the sugars and
starch transformation products at a density of 1055 and at a
1 Jnl. Chem. Soc. t 1897, 618. 2 Ibid., 02. 3 Ibid., 72.
r>F THE
DIVERSITY
r 'F
THE POLARIMETER 59
temperature of 60 F. (15'5 C.) are shown, Plate 1. fig. 52, but
the original paper referred to should be consulted where extreme
accuracy is essential.
Brown, Morris, and Millar point out, in defence of their having
used the 3 '86 factor for starch conversion products, that, so far
as ascertaining the percentage of the constituents is concerned,
the factor employed is a matter of indifference, provided the
specific rotatory powers and cupric reducing values of the con-
stituents corresponding with those of the particular divisor taken
are used in the calculation. They can be readily calculated into
the true amounts as soon as the true factor for the particular
starch conversion is known. At the same time, attention is
called to the fact that this is only strictly correct when the
solutions are of approximately the same density, and the con-
stituents possess identically the same divisor; but they do not
consider that the error thus introduced is sufficiently large to
vitiate their former work, or the conclusions based on it.
When the curves of the divisors for the different grades of
starch conversions are examined, it is found that for equal
concentrations the divisor for high conversions is greater than
that for low, in fact there appears to be some inverse ratio
between it and the amount of apparent maltose present.
It was found that if the mixed products of starch conversions
were assumed to consist of dextrin and maltose, and that the
maltose, which, according to the amyloin theory, exists in com-
bination with dextrin, was assumed to have the same solution
density as free maltose, it became possible to obtain by calculation
the divisor for the amyloin or dextrin constituent. This was done
for various conversions, and the curve thus found is given in the
table.
Though, as stated, it is somewhat improbable that the solution
factor for combined and free maltose would be the same, yet it
was found that when this dextrin curve was used in conjunction
with the maltose curve it was possible to determine, within
certain limits of concentration, and with a fair amount of
accuracy, the solution divisor for the mixed products of any
starch conversion brought about by diastase, the apparent maltose
percentage being either obtained from the opticity or cupric
reducing power of the solution.
We thus understand that where carbohydrate bodies have to
be examined for cupric reducing power, their amount is most
frequently deduced from the specific gravity of their solutions
by means of a solution factor. Consequently, it is usual to affix
60 THE BREWER'S ANALYST
in small characters the solution factor which has been used in
any particular case, such as K 3 . 8(3 or K 3 . 85 . This means that the
amount of solid matter in the first instance was estimated by the
3 '86 factor, in the second by the 3 '85.
The absolute reducing power may be readily obtained from
the statement of these on the 3 '8 6 factor when the true solution
factor is known. Thus the reducing power of maltose is K 3 . 86 =
61. If, as O'Sullivan assumed, the true solution factor for maltose
is 3 '93 14, then its real reducing power is
3-86: 3-9314:: 61: 62-12.
CUPRIC OXIDE REDUCING POWER.
It is shown in subsequent pages that several of the carbo-
hydrates reduce Fehling's solution, or, in other words, precipitate
different amounts of the copper contained in that standard
solution. According to the amount of copper precipitated, so is
the power of the carbohydrate in solution. The cupric oxide
reducing power is based upon the specific cupric reducing power
of a substance referred to dextrose as a standard of 100, and
such a figure is indicated by the letter K. Thus K = 50 signifies
a solution having half the reducing power of dextrose. As the
amount of reducing carbohydrate is almost invariably determined
by means of a solution factor previously referred to, it is con-
venient to add the divisor which has been used: thus K 3 . 86 = 50
explains that the reducing power is expressed on solid matter
determined by the factor 3*86.
Brown, Morris, and Millar propose to refer the reducing power
of carbohydrates to maltose taken as 100, and for indicating this
they use the letter R; thus RS-SS^ 50 indicates that the substance
has a reducing power of half that possessed by maltose, when the
amount of the substance is determined by means of the factor
3-86.
The cupric oxide precipitated by the various carbohydrates,
under favourable conditions, is as follows :
1 gram CuO = *7435 maltose.
'4535 dextrose.
'4715 invert-sugar.
Ptciiley's Brewer's Analyst.']
[PLATE I.
Solution Factors for Carbo-hydrates at Various Densities.
Specific Gravity at 15' C. (From Brown, Morris and
Millar, Journal of the Chemical Society, 1897, vol. Ixxi.,
p. 72.)
FIG. 52.
[To face p. 60.
PAKT III.
CARBOHYDRATES AND ALLIED SUBSTANCES.
PROTE1DS OR ALBUMINOIDS AND ENZYMES.
CARBOHYDRATES AND ALLIED SUBSTANCES.
THE name carbohydrate, embracing a very large number of
organic bodies, was originally applied to compounds which contain
in the molecule six atoms of carbon, or a multiple of this number,
together with hydrogen and oxygen present in the proportion in
which these elements unite to form water. This water, expressed
by the formula OH 2 , contains two atoms of hydrogen and one atom
of oxygen to form the molecule. In cane-sugar, expressed by the
formula C 12 H 22 O n , it will be seen that the same ratio between
the hydrogen and oxygen atoms exists, viz. 2:1. In inorganic
compounds the term " hydrate " is applied to those substances
which actually contain hydrogen and oxygen combined as water :
thus calcic hydrate Ca(OH) 2 when gently heated gives off the
combined water Ca(OH) 2 = CaO + OH 2 . Hence it was that the
carbohydrates were designated as hydrates of carbon. The term
carbohydrate, however, applied to the group of compounds about
to be considered, is in this sense a misnomer, since the elements
of hydrogen and oxygen are not contained within the molecule of
these compounds in the same sense as would be understood in the
case of an inorganic substance. The term was deduced from a
consideration of the empirical formulae of these bodies before their
constitution was as well understood as at the present time.
Recent researches, especially those by Emil Fischer, have shown
that the carbohydrates possess an exceedingly complicated
molecular structure, and that the group term carbohydrate
includes a very large number of substances which may be sub-
divided into groups having relationships and properties analogous
61
62 THE BREWER'S ANALYST
to, and not greatly differing from, the elementary group of the
hydrocarbon derivatives.
Most of the carbohydrate compounds occur in the vegetable
organism, but some few are also found in the animal kingdom.
The larger number are well known as constituting articles of food,
and it is needless to say that the majority are of the highest
physiological importance. They consist of several isomeric
groups, 1 most of whose members when in solution exhibit active
optical properties deviating the plane of polarised light either to
the right ( + ) or to the left ( - ), and are therefore said to be
optically active.
The more important carbohydrates which have an importance
from the brewing point of view are, according to their empirical
composition, divided into the following groups :
A. THE PENTOSE GROUP (C 5 H 10 5 ).
(a) Aribinose.
(b) Galaetoxylan.
(c) Xylose, Amylan, and Furfural.
B. THE CELLULOSE GROUP (C 6 H 10 5 ) n .
(a) Celluloses including the Hemicelluloses
and Oxycelluloses.
The molecular weight and constitution of most of the members
of this group are unknown, or have only been ascertained with
approximate accuracy.
(b) Starch. Amylo-cdlulose.
Granulose.
Soluble Starch.
(c) Dextrms. Amylo-dextrins.
Ery thro-dextrins.
A chroo-dextrin*.
(d) Inulin.
C. THE HEXOSE GROUP C 6 H 12 6 .
(a) Dextrose, (d-glucose) \
(b) Galactose V Aldose.
(c) Mannose }
(d) Levulose Ketose.
bodies or isomePS are bodies of identical empirical com-
position, but vary in properties. Thus starch, dextrin, cellulose, etc. have all
the same percentages of carbon, hydrogen, and oxygen, though different in
many other respects.
CARBOHYDRATES AND ALLIED SUBSTANCES 63
D. THE DrsACCHARiDB GROUP (C 12 H 22 O n ).
(a) Cane Sugar or Saccharose.
(b) Maltose or Malt Sugar.
(c) Lactose or Milk Sugar.
E. THE POLYSACCHARIDBS.
(a) Malto-Dextrins. (C 12 H 22 O n ) n .
(C 12 H 20 10 ) n .
(b) Rafflnose. C 18 H 32 16 .
We need only discuss the characteristics of the more important
of these bodies, thus :
A. THE PENTOSE GROUP (C 5 H 10 O 5 ).
Aribonose. Galactoxylan. Xylose. Amy Ian and Furfural.
The pentoses and their derivatives are found as constituents of
the husk and gummy matters of barley and malt. The pentoses
yield furfural when hydrolysed * by acids, and to this compound
is due the objectionable smell which always accompanies any
attempt to the further conversion of " spent " grains by means of
acid. Furfural is also formed to a slight extent at the mashing
stage, the acidity of the mash inverting galactoxylan and then
xylose into this compound.
B. THE CELLULOSE GROUP (C 6 H 10 5 ) n .
Hemicelluloses.
Oxy celluloses.
Starch. Amylo-cellulose, Granulose, Soluble Starch.
Dextrins. Amylo-dextrins, Erythro-dextrins, Achroo-dextrins.
Inulin.
CELLULOSE, HEMICELLULOSE, OXYCELLULOSE (C 6 H 10 5 ) n .
The Celluloses constitute the fundamental material of the
structure of all plants from the highest tree to the lowest fungus.
They are built up from soluble carbohydrates contained in
1 Hydrolysis. The term was suggested by Dr Armstrong. It is the
term used where the assimilation of the elements of water by a molecule of any
substance is immediately followed by its splitting up into other compounds.
Decompositions, like that of starch into dextrose, of cane-sugar into
dextrose and levulose, of the fats into glycerine and an acid, or of ordinary
ether into ethylic alcohol, which involve the fixation of the elements of water,
may all be said to be the result of hydrolysis.
64 THE BREWER'S ANALYST
protoplasm, and, with the exception of the very young cellular
tissue, always contain mineral matter. Cellulose is therefore very
seldom found pure, inasmuch as other substances pass from the
cells into the membrane, and there become fixed. If we micro-
scopically examine a thin section of wood or a little pith of the
elder, we see that the mass is made up of a great number of
irregularly shaped cells, and these are composed of cellulose.
Whilst the wood or other vegetable growth is still young the
substance of the cells is almost pure, but as the structure gets
older the cells become encrusted with resinous and other
secretions, and frequently assume a yellow, brown, or red tint.
The sources of cellulose are practically endless, and the forms in
which it appears are very numerous. Cotton is almost pure
cellulose, so also is elder pith, whilst w&jjfld it in very hard form
in the date stone and in vegetable ivory. ^^arley contains about
7 per cent, of it, cotton 91 '35 per cent., straw 46*22 per cent.,
and in different kinds of wood the percentage varies from 30 to
63. The purest forms of cellulose are cotton- wool, frequently
washed linen, and unglazed paper. If either of* these substances
be washed, first with weak alkali, and, after every trace of the
alkali has been removed, by distilled water, then submitted to the
action of weak hydrochloric acid, and finally again washed with
distilled water, we obtain cellulose iincontaminated by foreign
substances. As such, it is insoluble in the ordinary solvents such
as water, alcohol, ether, etc., or by prolonged boiling with dilute
acids or alkalies, but it dissolves in an ammoniacal solution of
cupric oxide, or in a strong solution of zinc chloride and hydro-
chloric acid.
Cellulose is a white, tasteless, odourless, innutritious substance,
which readily takes up moisture, but is unacted on by it, and
unaffected by exposure to air. It is coloured brown by iodine
solution, and is about one and a half times as heavy as water.
A mixture of strong nitric and sulphuric acids converts cellulose
into nitro-cellulose or gun-cotton, C 6 HK(N0 2 ) 3 O 5 , a substitution
which is reversed by alcoholic solution of potassic hydrosulphide,
reproducing cellulose. Besides ordinary forms of cellulose, which
in general resist the action of acids, alkalies, and enzymes, there
are certain celluloses which undergo hydrolysis with comparative
facility. Instances of these are the hemi-celluloses, which in the
seeds of some plants constitute the reserve material stored by the
parent plant for the sustenance of a future plant whilst in
embryo. Such reserve material takes the place of the starch
stored in the endosperm of the barleycorn. This cellulose is
CARBOHYDRATES AND ALLIED SUBSTANCES 65
readily hydrolysed by acids, and is converted into soluble
saccharine matters by the agency of enzymes secreted by the
growing plant. As examples, mention may be made of the cellu-
lose forming the walls of the starch containing cells of the
endosperm of barley, the dissolution of which takes place during
germination by the enzyme cytase, and the amylo-cellulose of
ordinary starch granules which is slowly hydrolysed by diastase
in the cold, but with facility at a temperature of 140 F. (60 C.).
Cross and Be van have shown that there are still further modi-
fications of cellulose present in many vegetable tissues, such as
those of the barley plant; and these, since they contain larger
percentages of oxygen than ordinary cellulose, have been named
" oxy-celluloses." They are extremely resistant to the action of
dilute alkalies, and, like the pentose sugars, the oxy-celluloses,
when distilled with hydrochloric acid, yield furfural ; and upon
hydrolysis with dilute acids (1 per cent, sulphuric) are partially
converted into a fermentable sugar, having probably the following
constitution,
XX
3 H 8 C 5 < >H 2 .
It was whilst studying this class of bodies that the author con-
ceived and patented the idea of treating "spent" grains for the
extraction of sugar. 1
The process consisted in converting "spent" grains in a similar
fashion to that in which raw grain is sometimes converted.
" Spent" grains contain from 2 to 10 per cent, of starch ; and it
was not only to recover this residual starch, but also to act upon
the cellulose and convert it also into sugar, that constituted the
idea. The sugar obtained was found to be of the furfuroid
character, and amenable, to an extent, to the fermentative action
of yeast. The results of the author's experiments in conjunction
with those of Cross and Bevan have long been recorded; 2 suffice
it to say that no commercial progress was made, after lengthy
experiments and heavy expenditure.
+ STARCH (C 6 H 10 5 ) n .
Amylo- Cellulose. Oranulose. Soluble Starch.
The formula for starch is as shown above, the value of n not
being known. Brown and Morris, as is shown hereafter when
1 Bailey and Ford Patent, No. 1788, 1896.
2 Jnl. Fed. Inst. Breivincj, 1897, 75.
66 THE BREWER'S ANALYST
considering the malto-dextrins, are of opinion that the formula
for starch cannot be less than 5(C 12 H 20 10 ) 20 , but it is yet doubtful
whether this formula will not at some future date be altered. At
any rate we may look upon starch as a carbohydrate containing
C, H, and O in the proportions in which these elements unite to
form water, and await developments for more light upon the
actual multiple of these elements.
Starch is a substance found in the form of small granules in
the cells of grain, legumes, and potatoes. It exists in nearly all
plants with the exception of the fungi. It is, in fact, the most
abundant material to be found in the vegetable world. It is
originally formed in the cells of the leaves of plants from the
carbon dioxide of the atmosphere, by the agency of chlorophyll
(the green colouring matter of leaves) in the presence of sunlight.
The starch thus formed may be looked upon as migratory, since
by enzymic action it is transformed into soluble sugars, passing
into the sap of the plant, and thence carried throughout the
plant, building up its fabric, reappearing at different stages of
the plant growth as cellulose, gummy matter, lignin, or trans-
formed again into starch as the reserve material in the seeds of
cereals, the tubers of the potato, etc. The study of the meta-
morphoses of starch in the living plant, from the assimilation of
carbon dioxide in the green leaves to the formation of starch in
the barleycorn, is an interesting study, and yields much valuable
information upon the process of germination. The classical
researches of Brown and Morris upon the " Physiology of Foliage
Leaves " l and the " Germination of the Gramineae," 2 should
therefore be consulted.
Starch is generally obtained in Europe from wheat, maize,
potatoes, and rice, and in tropical countries from the stems of
the palm and from the tubers of various plants; thus, in the
East Indies and the Philippine Islands, starch is obtained from
the pith of the sago-palm (Sagus loevis or Sagus rlium.pMi). This
comes into the market under the name of sago (a word meaning
bread). Arrowroot is the starch of the Maranta arundinacea and
indica, and a few other tropical plants growing in the West Indies,
Brazil, and the Southern States of America. Tapioca is derived
from Yatropha manihot, this, like sago, being subjected to pressure
to give the grains a peculiar form.
1 "A Contribution to the Chemistry and Physiology of Foliage Leaves"
(Jnl. Chem. Soc. Trans., 1893, 604-677).
2 " Researches on the Germination of some of the Gramineae " (Jnl. Chem.
Soc. Trans., 1890, 458-528).
CARBOHYDRATES AND ALLIED SUBSTANCES 67
Starch being heavier than water, its density at a temperature
of 67-5 F. (19-7 C.) being 1-505, has the property, when mixed
with it, of sinking with proportionate rapidity, and we may observe
that the bottom layer is "remarkable for great toughness. It is
never found in a state of purity, but always occurs mixed with a
greater or less amount of nitrogenous matter. In order to purify
it, until within recent years the starch was mixed with water
and allowed to stand until fermentation set in, this being caused
by the action of aerial ferments, the result being that the formation
of acetic, butyric, and lactic acids in time split up the nitrogenous
matter, and a subsequent washing with water left the starch pure.
There are two objections to this method of preparing starch :
firstly, the lengthy time necessarily occupied ; and secondly, the
objectionable odour evolved from the fermentation, which renders
the manufacture a nuisance to the neighbourhood. It became
necessary, therefore, to adopt fresh means for purifying it, and this
is now performed by dissolving the nitrogenous bodies with caustic
soda instead of the previous objectionable method of fermentation.
The steep water is first made faintly acid by the addition of a
little sulphuric acid, and the starch is afterwards treated with
water containing y-g^th of its weight of caustic soda, or a solution
containing 200 grains or J ounce of the alkali per gallon.
The external characteristics of starch granules can only be
distinguished by the aid of the microscope on account of their
minute size ; and by the aid of this instrument it was discovered
that not only does the size of the granules vary in every species of
starch, but that each species exhibits its own particular form and
structural markings. Adulteration can thus be detected, and
admixture of cheap potato starch with the more expensive
wheaten starch may be approximately measured by microscopical
observation.
Though the cells of every species of starch vary in size and
shape, they nevertheless exhibit certain similarities in structure.
Each has a dark point, central in some, eccentric in others, known
as the "hilum." Round this are seen a series of concentric lines,
an appearance caused by the peculiar structure of the granules,
which are built up of layers containing varying amounts of water.
The hilum is always rich in water, and each layer alternately
contains more or less water, the outside layer being always most
free from moisture and richest in substance. As a consequence
of the proportion of water increasing from the outside of
the granule inwards to the hilum, fissures radiating from the
hilum towards the periphery often arise as the granule becomes
68 THE BREWER'S ANALYST
dry. By steeping starch granules in alcohol, which entirely
deprives them of water, all appearance of stratification disappears,
but the lines reappear if the granules are moistened with water.
If they are treated with dilute alkali or acid, the appearance of
stratification is rendered much more distinct.
The following sketches, figs. 53 to 64, Plates II. to VII., show the
microscopical appearance of the more important starches ; and the
table, by Gait, 1 gives their outline, measurement, surface, hilum,
and markings.
Air-dried starch contains from 15 to 20 per cent, of moisture,
the last traces of which it retains with remarkable pertinacity,
consequently it is almost impossible to remove the whole of the
moisture by heat alone without at the same time causing a
chemical alteration in the starch substance itself. To avoid this,
Dafert 2 proposes to remove the hygroscopic water by drying the
starch in vacua at 212 F. (100" C.). Absolutely dry starch
attracts moisture with such avidity that when moistened with
water a perceptible rise of temperature takes place, a phenomenon
which shows that the last portions of water are in a state of
chemical combination.
Starch is an exceedingly inert substance, insoluble in cold
water, alcohol, ether, and ammonia cuprate, the latter showing
its difference from cellulose ; but it dissolves in potassic hydrate
solution, in consequence of the formation of a potassium derivative.
On treating with acetic anhydride it is converted into a tri-
acetate, C 6 H 7 2 (C 2 H 3 2 ) S .
It may be heated, when dry, to a temperature of 300 F. (148*8
C.) without change, but by a temperature of from 300 to 400 F.
(148 '8 to 204'4 C.) it is converted into a substance soluble in
cold water, termed dextrin or British gum, and at temperatures
above this it is decomposed.
Starch is largely used in the arts for laundry purposes, paper
sizing, bookbinding, weaving and finishing calicoes, also for pre-
paring the thickening for colours and mordants in calico printing,
for dusting the formes in metal founding, and a variety of other
purposes.
So long ago as 1716 Leuwenhoek asserted that the cell -walls of
the granules differ from the cell contents ; and Raspail confirmed
this assertion, believing, however, that the cell contents were
identical with gum arabic. On the other hand, Guibort came to
the conclusion that both the above possessed the same chemical
1 TJie Microscopy of the Starches.
2 Jnl. f. prakt. Chem., Ixxiii. 51.
Bailey's Brewer's Analyst.]
[PLATE U.
FIG. 53. Potato Starch, x 116.
(Galt-Bailliere, Tindall, and Cox.)
FIG. 54. Rye Starch, x 116.
(Galt-Bailliere, Tindall, and Cox.)
[To face p 68.
Bailey s Brewer's Analyst.']
[PLATE III.
FIG. 55. Rice Starch, x 300.
(Macmillan.)
FIG. 56. Oat Starch, x 380.
(Galt-Bailliere, Tindall, and Cox.
[To face p. 68.
Bailey's Brewer's Analyst. '
[PLATE IV.
FIG. 57. Maize Starch, x 300.
(Macmillan.)
FIG. 58. Pea Starch, x 116.
(Galt-Bailliere, Tindall, and Cox.)
[To face p. 68.
Bailey's Brewer's Analyst. ]
[PLATE V.
FIG. 59. Tapioca Starch. xl!6.
(Galt-Bailliere, Tindall, and Cox.)
FIG. 60. Sago Starch, x 116.
(Galt-Bailliere, Tindall, and Cox.)
[To face p. 68.
Bailey's Brewer's Analyst,.
FIG. 61. Barley Starch, x 116.
(Galt-Bailliere, Tindall, and Cox.)
[PLATE VI.
FIG. 62. Wheat Starch, x 116.
(Galt-Bailliere, Tindall, and Cox.)
[To face p. 68.
Bailey's Brewer's Analyst.'
[PLATE VII.
FIG. 63. Tons les Mois Starch. x 116.
(Galt-Bailliere, Tindall, and Cox.)
FIG. 64. Bermuda Arrowroot Starch. x 116.
(Galt-Bailliere, Tindall, and Cox.)
[ To face p.
CARBOHYDRATES AND ALLIED SUBSTANCES
69
TABLE SHOWING THE LEADING MICROSCOPICAL CHARACTERS OF THE
MORE IMPORTANT STARCHES.
Fi
Outline.
Measuremen
Surface.
Hilum.
Markings.
60
Potato.
Oval or ellip
tical.
mm.
Js In long dia
" meter ;
J 7 in short
diameter.
Uniformly
but slightly
convex.
Dark spot nea
narrow end.
Concentric rings ;
closed, or almos
closed, curves.
61
Rye.
Circular.
A
Convex,
spherical.
Crucial o
radial, cen
tral, large.
Exceedingly faint
complete concen-
tric rings.
62
Rice.
Rectilinear
and poly-
gonal.
*i
Flat.
None.
None.
63
Oat.
Rectilinear
and poly-
gonal.
0(7
Flat or slight
ly convex 01
concave.
None.
None.
64
Maize.
Rectilinear
and poly-
gonal.
1
Uneven, anc
slightly
concave.
Stellate or ir
regular, large
central.
None.
65
Pea.
Ren if or m.
2 V in long dia-
meter ;
& in short
diameter.
Convex, with
central lon-
gitudinal
depression.
Large, si it-like
longitudinal,
central. '
Appearance of
concentric rings
forming closed
curves.
66
Sago.
Rounded ;
some partly
angular.
vfa in long
diameter ;
n in short
diameter.
Uniformly
and highly
convex.
Near large and
rounded end,
large, slit-like
or irregular,
transverse.
Occasionally a few
very faint, gener-
ally incomplete,
concentric rings.
67
Tapioca.
Rounded ;
some partly
angular.
^
Uniformly
convex.
Slit-like, trans-
verse, stel-
late, central.
Like sago, but still
more indistinct.
68
Wheat.
Circular, or
nearly so.
*
Convex.
Dark spot, ec-
centric.
Occasionally a few
exceedingly faint
concentric rings.
69
Barley.
Circular,
lenticular.
^00
Convex.
Dark spot, ec-
centric, sel-
dom apparent.
Very rarely, faint
indication of con-
centric rings.
70
Jermuda
arrow-
root.
Oval.
V in long dia-
meter;
3*5 in short
diameter.
Uniformly
but slightly
convex.
yfear broad
end, circular,
crucial, trans-
verse line or
slit.
Taint concentric
rings, in a few
cases extending
about two-thirds
of length of grain.
71
'ous'les-
Mois.
Irregularly
oval or
elliptical.
Jjy in long
diameter ;
T&J in short
diameter.
Uniformly
but very
slightly
convex.
Dark spot near
narrow end.
oncentric rings
extending for less
than one -third of
length of grain.
70 THE BREWER'S ANALYST
composition, and that they only differed physically. 1 The
structure of the starch granule was then carefully examined by
Fritsche, 2 and the classical researches of Naegeli 3 proved that
starch is a mixture of several isomeric compounds. Its internal
portion consists of what is termed yranulose with a small portion
of starch cellulose, whilst the outer coating consists principally,
if not entirely, of this latter substance. The outer coating or
cellulose of the starch granule protects the inner content or
granulose from being acted upon either by cold water or diastase,
and before any action can therefore take place it becomes necessary
to burst the granules either by attrition or heat.
There is great divergence of opinion as to whether or not the
granulose upon being set free from the granule enters into a state
of solution. Some say that it does not, since if it did so it would
readily pass through cell membrane, which property it does not
possess. Brown and Heron believe that the granulose is in a true
state of solution, and that the viscosity of starch paste is due to
the swollen state of the cellulose. They found the viscosity to
vary considerably. The more slowly the starch has been dried
and the lower the heat at which this has been effected, the more
viscous the solution ; in fact they found the difference in viscosity,
due to the varied methods of preparation, to amount to more than
three to one. Moritz and Morris express the opinion that on
boiling starch the granulose is converted into soluble starch.
In any case, when starch is heated with water the granules-
undergo a singular change in their structural condition. They
take up large quantities of water, become swollen, and in time,
if the temperature of the water is high enough, burst. A
gelatinous mass is formed which is designated as starch paste,
the process itself being termed the production of starch paste, or
the gelatinisation of starch.
During the heating the volume of the liquid becomes greater.
According to Pay en, the increase of volume amounts to 142 per
cent, at a temperature of 140 F. (60 C.), and to 1255 per cent,
at 158-161-6 F. (70-72 C.). The higher the temperature
of the water, the greater the swelling of the granules, and also
the greater the diffusion. The temperature at which starch
granules begin to swell, and also that at which a complete
transformation into paste occurs, differs according to the nature
of the starch.
Soluble Starch is conveniently prepared, according to
1 Jnl. Cliem. Med., v. 9. 2 Pogg. Ann., xxii. 129.
3 Jahresber. d. C/iemie, 1859, 544.
CARBOHYDRATES AND ALLIED SUBSTANCES 71
Lintner, 1 by digesting potato starch with a 7 '5 per cent, solution
of ordinary strong hydrochloric acid at a temperature of 60 F.
(15*5 C.) for one week, afterwards washing the starch by repeated
decantation until the washings are perfectly free from acid; or,
according to Brown and Morris, 2 a 12 per cent, solution of hydro-
chloric acid may be employed, in which case digestion for twenty-
four hours suffices. The starch granules undergo no apparent
physical change by the process, as is shown by microscopical
examination, in which case it will be seen that the granules retain
their original appearance.
Soluble starch is precipitated by a large addition of alcohol,
also by many metallic oxides, as lime, baryta, and lead oxide. It
is coloured an intense deep blue by iodine solution, this property
having been discovered by Gaultier de Clanbry in 1814. The
reaction, however, is much influenced by temperature ; the
lower the temperature the more sensitive is the reaction. At or
near the boiling-point of water the coloration does not appear at
all, but a deep blue makes its appearance as the solution cools,
provided the solution is not subjected to prolonged heating.
The blue colour does not show itself so readily, nor is it so
pure, in the presence of other bodies such as tannin, malt extract,
beer, yeast, etc. Whether the blue substance formed is a true
chemical compound or not has not been definitely settled.
The colour also varies according to the nature of the starch ;
thus potato starch gives a deep blue, wheat-starch a colour
inclined to violet. This is accounted for by a larger amount of
the cellulose, which is coloured brown by iodine, being contained
in some of the starches.
Two starches have been met with by Dafert and Kreusler, 3 the
one in a species of rice, the other in a kind of millet, which are
coloured from red to brown by iodine solution. The opticity of
soluble starch is given as [a]j 3 ' 86 + 216 by Brown and Morris, and
as [a] D + 200 by Lintner. Brown, Morris, and Miller state that
the opticity in 2*5 to 4*5 per cent, solution is at 60 F. (15'5 C.)
[a] D 202. It has no reducing action on Fehling's solution.
When acted on by diastase in the cold it is decomposed in ten
minutes to the No. 8 equation. When, however, the action of
diastase is allowed to proceed for ten or twelve days in the cold,
soluble starch is entirely converted into maltose. 4
1 Jnl. f. praM. Chem. , xxxiv. 378.
2 Jnl. Chem. Soc., 1889, 450.
3 Landwirth. Jahrbuch, xiii. 767, xiv. 831.
4 Lintuer, Jnl. /. prakt. Chem., 1887.
72 THE BREWER'S ANALYST
By the action of diastase or acid on soluble starch, under
suitable conditions, identical sugars are formed, and the inference
naturally arises that the intermediate products (malto-dextrins),
formed by the respective agents, are identical.
The transformation of soluble starch to dextrins and malto-
dextrins can be followed to a certain extent by the iodine reaction,
the deep blue tint produced in soluble starch changing to red
upon the starch hydrolysing to dextrin.
Brown and Morris, 1 by employing Raoult's method, found the
molecular weight of soluble starch to vary from 20,000 to 30,000 ;
and on the asumption that the stable dextrin of the No. 8
equation constitutes one-fifth of the molecule, they concluded that
its molecular weight is 32,400, and its formula 5(C ]2 H 20 10 ) 5 , .
The question the brewer has to take into consideration is how
best and most economically he can transform starch into dextrin,
maltose, and malto-dextrin, in proportions suitable for any
particular beer. No matter whether he employs the starch of a
cereal such as rice or maize, he obtains the same fermentable
products as those produced by the employment of oats or barley.
Certain starches, however, produce somewhat objectionable
flavoured worts, and such worts are prone to quickly acidify ;
hence it is that only certain raw grain starches are employed by
the brewer.
+ DEXTRIN (C 6 H 10 5 ) n .
Amylo-dextrins. Erythro-dextrins. Acliroo-dextrins,
By heating dry starch to a temperature of from 300-400 F.
(14S'S-204*4* C.), as already mentioned, a substance, soluble
in cold water, termed dextrin or British gum, is produced.
Dextrin forms an intermediate stage in the conversion of starch,
whether effected by mineral acids or malt-extract (diastase).
There are three kinds of dextrin, designated amylo, erythro,
and achroo, the amylo- and erythro-dextrins giving a red or
brownish colour with iodine solution, the achroo-dextrins
being unaffected by this reagent. There has been great con-
troversy as to the existence of different types of dextrin, Greiss-
mayer, O'Sullivan, Nsegeli, and other investigators describing
several.
The dextrins are neutral, tasteless substances, soluble in
water, dilute alcohol or naphtha, but insoluble in absolute
alcohol or ether.
1 Jnl. Chem. Soc. t 1889, 465.
CARBOHYDRATES AND ALLIED SUBSTANCES 73
C. THE HEXOSE GROUP C 6 H 12 6 .
+ Dextrose (d-glucose). Galaciose. Mannose.
Levulose (fructose).
+ DEXTROSE (d-glucose} C 6 H 12 6 .
Dextrose or d-glucose is one of the sugars found in great
abundance in the vegetable kindom. Ripe sweet fruits, such as
grapes, plums, figs, etc., contain, in addition to levulose and
small quantities of cane-sugar, large quantities of this substance.
It is also met with in the stems and seeds of cereals and in the
flowers of many plants from which bees derive honey ; it is also
found in honey.
Compounds of dextrose are frequently met with, termed
glucosides, which readily split up under the hydrolysing action of
dilute acids or enzymes into dextrose and their other constituents.
Dextrose is now largely prepared from starch and starchy
materials by the action of dilute mineral acids, the product thus
obtained consisting of a mixture of dextrin, maltose, and dextrose,
the percentages of these sugars depending upon the conditions
and length of time the hydrolysis is allowed to proceed. But if
the hydrolysis is prolonged to its fullest limit, the dextrin first
formed is converted to maltose and the latter to dextrose. In
such cases other substances besides dextrose are formed, amongst
which is supposed to be a substance termed gallisin. Of their
character, little of a satisfactory nature is known.
Dextrose is only half as sweet as cane-sugar ; it is readily soluble
in water and dilute alcohol, but is completely insoluble in absolute
alcohol. It is not charred or blackened by concentrated sulphuric
acid, as is cane-sugar, but if heated with solutions of the alkalies
a brown coloration is produced, and with dilute acids prolonged
heating forms brown substances termed ulmin and ulmic acid.
On heating dextrose to temperatures between 230-309F.
(110-154 C.) caramel is produced. On heating to 340F.
(171 C.) water is given off and glucosan is formed; whilst on
still further heating, the substance is decomposed.
Dextrose readily combines with oxygen, and hence is able to
reduce the oxides of several metals to the metallic form ; whilst
in the case of some metals such as copper, the higher oxide is
reduced to the lower, viz., CuO to Cu 2 O. On this property the
methods of determining dextrose quantitatively are founded.
Dilute nitric acid oxidises dextrose to saccharic acid (C 6 H 10 8 ).
Solutions of dextrose are readily fermented by yeast, maltose
74 THE BREWER'S ANALYST
requiring to be first hydrolysed to dextrose by the enzyme
maltose contained in yeast, and cane-sugar to be first hydrolysed
to invert by the enzyme invertase contained in yeast, before
fermentation commences and splits the sugar up into alcohol and
carbon-dioxide. Upon fermenting, dextrose yields 48*67 per cent,
of alcohol. It possesses an optical activity of [a] D3 . 86 = 51'7, and
its cupric-oxide reducing power is K 3 . 86 = 100.
Dextrose solutions, like those of levulose and maltose, produce
an osazone when treated with phenyl-hydrazine.
If 1 gram of dextrose is dissolved in 50 c.c. of water, and 2 grams
of phenyl-hydrazine dissolved in 2 grams of 50 per cent, acetic
acid are added, the mixture upon being treated throws down a
dense yellow precipitate. The action is complete in one hour.
The precipitate, microscopically examined, will be found to consist
of needle-shaped crystals, some of which may occur in fan-shaped
aggregates. The precipitate, when collected, washed with hot
water, and dried at 212 F. (100 C.), will be found to be very in-
soluble in boiling water, which characteristic assists in its
identification.
The reaction of phenyl - hydrazine with the hexoses is as
follows : If one molecule of phenyl-hydrazine is allowed to act
on one molecule of a hexose, a normal hydrazone is formed :
Dextrose. Phenyl-hydrazine. Hydrazone.
CH 2 .OH(CH.OH) 4 . CHO + C 6 H 5 NHNH 2 = CH 2 .OH(CH.OH) 4 .
CH + H 2
II
N-NH.C 6 H 5 -
But if two molecules of phenyl-hydrazine are used, an osazone
is obtained :
CH 2 .OH(CH.OH) 3 .C - CH = N - NH.C 6 H 5
II
N
NH.C 6 H 5 .
Glucosazone.
Dextrose solutions, like those of some other carbohydrates,
also possess the phenomenon of muta-rotation. A freshly-prepared
solution shows an opticity nearly twice as great as that given
after standing, and the opticity only becomes stationary after a
lapse of about 24 hours. Two minutes boiling or the addition
of a very small quantity of caustic potash or ammonia (O'l per
cent.), however, at once fixes the rotatory power. Besides by the
hydrolysis of starch, dextrose may be prepared from cane-sugar,
CARBOHYDRATES AND ALLIED SUBSTANCES 75
in which case the product consists of nearly equal weights of
dextrose and levulose, otherwise known as invert-sugar. The solid
portion of commercial samples of invert consist of crystallised
dextrose, which may be washed with alcohol, dissolved, and
recrystallised from methyl-alcohol. The dextrose then separates
as hydrate (C 6 H 12 O 6 + H 2 0).
- LEVULOSE (Fructose) C 6 H 12 O 6 .
Levulose exists in association with dextrose in grapes, ripe
fruits, honey, and in the stems and seeds of cereals; and is
present in invert-sugar to the extent of nearly half the latter's
weight. It may be separated from invert by making a solution,
mixing an equal weight of finely-powdered slaked lime, and
maintaining for some time at a low temperature. The lime forms
a solid compound with the levulose known as insoluble calcic
levulosate, while the dextrose forms a compound which is freely
soluble, and may be separated by nitration and washing. The
residue is then mixed with water, and on passing a current of
carbon-dioxide through the liquid, decomposition occurs, the
lime being precipitated as carbonate, and the levulose passing
into solution. This solution may be rendered anhydrous by
evaporation in vacuo over sulphuric acid. Thus prepared,
levulose is a colourless, uncrystallisable syrup, distinctly sweeter
than dextrose, and more soluble than the latter in alcohol. By
careful recrystallisation, it may be obtained in fine silky crystals,
which melt at a temperature of 203 F. (95 C.).
Levulose turns a polarised ray of light strongly to the left,
hence its name, the angle of rotation being [] D 3-sG = - 93'7,
and it has a cupric-oxide reducing power of K 3 . 8(j = 92'4.
The polarisation is thus more powerful than that of dextrose
to the right, so that a solution of invert-sugar, containing equal
quantities of each sugar, possesses a distinct levo-rotatory power.
The levo-rotatory angle diminishes as the temperature of the
solution rises, so that at a certain temperature levulose apparently
possesses no rotatory power at all, since the action of the negative
levulose is then exactly balanced by the positive rotation of the
dextrose, and at about this temperature invert-sugar becomes
dextro-rotatory.
Levulose ferments in contact with yeast, but not so readily as
does dextrose, a fact which favours the theory that the sluggish-
ness of its fermentation is due to it not being able to diffuse so
readily as dextrose through the walls of the yeast cells.
76 THE BREWER'S ANALYST
When levulose is heated strongly it is converted into levulosan
(C C H 10 5 ), a body isomeric with glucosan and produced in the
same way from dextrose by the expulsion of water. It comports
itself in many respects in an almost similar manner to dextrose,
and is oxidised into saccharic acid by contact with dilute nitric
acid.
Solutions of levulose form an osazone when treated with phenyl-
hydrazine.
D. THE DISACCHARIDE GROUP C 12 H 22 O n .
Cane-sugar or Saccharose. Maltose or Malt-sugar.
Lactose or Milk-swjar.
+ CANE-SUGAR C 12 H 22 lr
Cane-sugar is freely soluble in water, a cold, saturated solution
at 60 F. (15-5 C.) contains about 66'3 per cent., a boiling
solution about 82-5 per cent. The gravity of a solution increases
in a slightly greater ratio than the percentage of sugar, and the
difference in ratio becomes still more pronounced as the quantity
is further increased.
Cane-sugar is insoluble in ether, slightly soluble in absolute
alcohol, and more so in dilute alcohol, the solubility increasing
with the dilution of the alcohol. It has no reducing action on
Fehling's solution, melts at a temperature of 320 F. (160 C.).,
and on cooling solidifies to an amorphous mass, which, after some
time, becomes crystalline.
When heated for some time to 338 F. (170 C.) it is split up
into dextrose and levulose, but if exposed to a higher temperature,
356-392* F. (1SO-200 C.), the mass becomes first yellow and
then brown, forming caramel. Heated to a still higher tempera-
ture, decomposition takes place with evolution of combustible
gases and acid vapours, a light porous mass of carbon being left
behind.
If a little concentrated sulphuric acid be added to cane-sugar
syrup, an immediate and characteristic action ensues ; the sugar
is deprived, by the acid, of the elements of water, and its carbon
separates as a solid swollen black mass, of much greater bulk
than the syrup from which it is derived. If, however, a solution
containing not more than 30 per cent, of cane-sugar is heated
with dilute acid, the sugar, instead of parting with, takes up
the elements of water and is hydrolysed into a mixture of dextrose
and levulose, otherwise known as invert-sugar. The same change
CARBOHYDRATES AND ALLIED SUBSTANCES 77
is brought about when cane-sugar solution is placed, under
suitable conditions, in contact with yeast, invertase, the enzyme
of monilia Candida, or malt extract. In the latter cases, how-
ever, the action is very slow. The reaction which results is the
same whichever agent be employed ; it consists in the assimilation
of water by the cane-sugar molecule, followed by its separation
into the two different kinds of sugar named, which, though of
very different properties, have the same formula.
The following equation expresses the change : -
C 12 H 22 O n + H 2 = C 6 H 12 6 4 C 6 H ]2 6 .
Cane-sugar. Water. Dextrose. Levulose.
Invert-sugar.
Yeast ferments cane-sugar solutions of weak or medium strength,
but is unable to ferment solutions of 50 to 60 per cent, strength,
or any solutions to which large quantities of glycerine have been
added : the enzyme zymase, however, ferments these solutions
readily.
Cane-sugar forms compounds (saccharates) with several bases,
such as potassium, strontium, lead, etc., all of which are de-
composed by carbon-dioxide.
It does not form a compound with phenyl-hydrazine, but when
heated in a solution of the acetate of that base, it first suffers
inversion into dextrose and levulose, these latter sugars uniting
with the phenyl-hydrazine to form glucosazone. Cane-sugar
solutions of medium dilution and under suitable conditions are
completely fermentable by yeast, but in such instances the
fermentation is not a direct one, the sugar being first split up
into invert.
Many bacteria are able to induce peculiar fermentations in
solutions of cane-sugar, in which such bodies as lactic acid,
butyric acid, mannitol, etc., are produced.
+ MALTOSE C 12 H 22 O n .
Although belonging to the same group as cane-sugar, maltose
has few properties in common with that most familiar substance.
It nowhere in nature exists ready formed to any great extent. It
is surmised that plants, during their growth, transform a portion
of their starch into maltose as and when they require the latter
for food, but the amount required is so infinitesimal that no large
quantity is found to exist therein.
78 THE BREWER'S ANALYST
Maltose was discovered by De Saussure in 1819, but the
discovery was overlooked or forgotten. It was again discovered
by Dubrunfant 1 in 1847, but again overlooked or forgotten. In
1872, however, C. O'Sullivan 2 rediscovered it.
O'Sullivan prepared it by acting upon gelatinised potato starch,
with diastase at about 90 F. (32'2 C.). Chloroform was added
to prevent bacterial growths, and the infusion allowed to stand for
ten days. The solution was then evaporated to a syrupy
consistency, when maltose slowly crystallised out which was
purified by. being dissolved in alcohol and recrystallised. It
separates from an aqueous solution in needle form, and contains
one equivalent of water of crystallisation ; but when separated
from alcoholic solution it is anhydrous. It is a white substance,
soluble in water, but sparingly soluble in alcohol. It reduces
Fehling's solution in a degree equal to about two-thirds of its
weight of dextrose. This reduction is stated by O'Sullivan to be
equal to 65 per cent, of its weight of dextrose, but Brown and
Morris state the percentage to be equal to K 3 . 86 = 61, which, how-
ever, is practically the same thing, when allowance is made for the
fact that O'Sullivan employed the factor 3 "85 in place of the
now commonly used factor 3 '86.
According to Soxhlet, with an excess of undiluted Fehling's
solution and an approximately 1 per cent, solution of maltose, 100
parts of maltose invariably yield 127 '3 parts of cupric oxide, or
113 parts of copper. A series of tables for the estimation of
maltose have been prepared by Kjeldahl. 3
The optical activity of maltose is [a] D3 . 8fi = 135'9. It is
converted into dextrose when heated for a short time with
dilute mineral acid, the best temperature for the hydrolysis being
176 F. (80 C.) to 194 F. (90 C.). Malt extract or diastase is
unable to effect any change in it, whilst in contact with yeast,
under suitable conditions, it is hydrolysed to dextrose under
the influence of a special enzyme contained within the yeast
termed maltase or glucase, and is further decomposed with the
production of from 51 to 52 per cent, of alcohol. When in
company with dextrose the latter is fermented first.
A hot solution of maltose, heated with phenyl-hydrazine, forms
osazone which separates on cooling as yellow needles, and which
melt and decompose at a temperature of 390 F. (198*8 C.).
1 Ann. Chim. et Phys., xi. 379.
2 Jnl. Chem. Soc. Trans., xxv. 579.
3 Med. Carlsb. Lab., 1895, 1.
CARBOHYDRATES AND ALLIED SUBSTANCES 79
E. THE POLYSACGHARIDES.
+ Malto-dextrins (C 12 H 22 O n ) B .
( C 12 H 20lo)"-
Raffihose C 18 H 32 O 16 .
+ Malto-dextrins (C 12 H 22 O n ) n .
( C i2 H 2oio)-
The transformation products in a starch conversion possessing
an [] D 150'3 consist of :
Maltose . . . 80'8 per cent.
Dextrin . . 19'2
KHM)
The optical activity of a starch transformation effected by
unrestricted diastase falls rapidly from [a] D 202, representing the
original soluble starch, to [a] D 150'3 representing a so-called
complete conversion, and when it reaches this stage the velocity
of the transformation change is checked; [a] D 150'3 therefore
represents a well-defined point in the hydrolysis of starch. An
equation representing this change, commonly called the " No. 8 "
equation, is given thus :
[5(C 12 H 20 10 )] + 4H 2 - 4C I2 H 22 O n + (C 12 H 20 10
Starch. Water. Maltose. Stable dextrin.
This equation represents that four-fifths of the starch molecule
is converted into maltose and one-fifth into stable dextrin ; but
the amount of maltose in the starch transformation products is
not four-fifths the weight of these products, owing to the fixation
of water during hydrolysis, hence the proportion 80 '8 maltose to
19*2 dextrin in the products of a complete conversion.
The starch molecule is, however, much larger than [5(C 12 H 20
o w )].
Brown and Millar 1 bring forward evidence to show that the
molecule of stable dextrin is [20(C 12 H 20 10 )], and therefore that
the molecule of soluble starch must be at least five times as large.
According to this view, the conversion of soluble starch into
maltose and dextrin is represented as follows :
(C 12 H 20 10 ) 20 + 80H 2 - 80C 12 H 22 O n + [20(C 12 H 20 10 )]
(C 12 H 20 ]0 ) 20 Maltose. Stable dextrin.
(^12-^-20^10)20
Soluble starch.
1 Jnl. Chem. Soc., 1899, Jxxv. 317.
80 THE BREWER'S ANALYST
The so-called " stable " dextrin, although it strongly resists the
action of diastase, is eventually hydrolysed to maltose and
dextrose if the action of the diastase is very prolonged ; but
the velocity of the action is exceedingly slow as compared with
the velocity of hydrolysis of starch to maltose and dextrin.
RAFFINOSE C 1S H 32 16 .
Raffinose was discovered by O'Sullivan as a constituent, to a
small extent, in barley ; its common origin, however, is the sugar-
beet. The formula is C 1S H 32 16 + 50H 2 , and it crystallises in small
needles or prisms which readily dissolve in water but are only
slightly soluble in alcohol and possess but a faint sweetness.
It does not reduce Fehling's solution, its rotatory power being
[a] D3 . 86 = 104-5.
When heated for a short time with dilute mineral acid, it
splits up into equal molecules of levulose and of a disacharide
isomeric with lactose, called "melibose." This latter substance,
on prolonged treatment with dilute acid, splits up into galactose
and glucose in equal molecules. 1
On fermentation, raffinose behaves differently with various
yeasts; some are able to hydrolyse and ferment it completely,
others only partially invert it into melibose and levulose, the latter
sugar being alone fermented.
It is not known whether raffinose has any important influence
upon worts or beers.
a and (3 AMYLAN.
These bodies were found by O'Sullivan in barley, wheat and
rye. Barley contains about 2 per cent, of a-amylan and about
0'3 per cent, of ft-amylan.
They were obtained from barley by extracting the cereal first
with alcohol and then with water. The aqueous solution was
concentrated by evaporation, and strong alcohol added, which
precipitated the two bodies. The precipitates were treated with
cold water, which dissolved out the fi-amylan and left the a-amylan.
The latter was afterwards dissolved in dilute hydrochloric acid,
and precipitated therefrom by alcohol.
Both these bodies are levo-rotatory, and have the following
opticities :
a-amylan . . [a] j = - 24
/3-amylan . . . []j= -73
Hydrolysis by dilute acids converts them into glucose.
1 Berichte, xxii., 1678 and 3118.
PROTEIDS OR ALBUMINOIDS AND ENZYMES 81
GUM.
Lintrier separated a small amount of gum from beer, and a
similar, if not identical, substance was afterwards found in barley,
malt, straw, bran, and "spent" grains. The gum forms very
viscous solutions which are very difficult to filter. The gum is
dextro-rotatory, does not reduce Fehling's solution, and is pre-
cipitated by lead acetate. Like many other gums, it gives a
cherry-red colour with phloroglucin and hydrochloric acid, also a
bluish-green colour with orcein and hydrochloric acid, its
presence in beer being demonstrated by these reactions.
Lintner and Diill l have shown that the gum may be regarded
as galactoxylan ; for when boiled with dilute acid it is resolved
into galactose and xylose. It is evidently formed by the union of
a molecule of galactose with a molecule of the penta glucose sugar,
xylose, with the elimination of a molecule of water, thus :
C 6 H 12 6 + C 5 H 10 5 - H 2 = C n H 20 10 .
Galactose. Xylose. Water. Galactoxylan.
PROTEIDS OR ALBUMINOIDS AND ENZYMES.
Serum, Fibrin, Egg, Casein, and Plant Albumins Molecular
Constitution of the Proteids Effects of Hydrolysis on the
Proteids Chemical Reactions of the Proteids Members of
the Proteid Groups The Proteids of Barley The Proteids
of Malt Enzymes or Hydrolysis Chemical Composition
of the Enzymes Enzyme Groups Action of Proteoiijtic
Enzymes on the Proteids.
DIASTASE, GLUCASE OR MALTASE, CYTASE, INVERTASE, ZYMASE.
The proteids or albuminoids, otherwise spoken of as protenaceous,
nitrogenous, or albuminous bodies, form the chief part of the solid
constituents of the blood, muscles, nerves, glands, and other
organs of animals. They occur in small quantities in almost every
part of vegetables, and in large quantities in the seeds, and in
fact enter so largely into the composition of organic substances
that they have been regarded as building up the animal and
vegetable worlds. They are of great importance to man's
existence ; both plants and animals lay up reserves or stores of
them in various parts of their tissues for contingent use, so that
should their food supplies be suddenly withdrawn, neither the
plant nor animal would immediately die, but would live for a time
1 Zeit.f. angew. Chem., 1897, 538.
82 THE BREWER'S ANALYST
on its reserves. Before these reserves, however, can be made
available for the operations of nutrition, they must first be
converted from their inert and mostly insoluble state into a state
of solution and adaptability to circulate in the nutritive fluid
which constitutes the alimentary atmosphere or environment of
the protoplasmic elements. We shall hereafter more readily
perceive how these operations are performed, so for the present
may merely look to the characteristics of a few specially studied
proteid bodies.
ALBUMIN.
Of the various forms of albumin we have serum albumin, fibrin
albumin, egg albumin, and plant albumin or gluten.
Serum albumin is the most abundant albuminous substance
in animal bodies. It may be obtained tolerably pure, from blood-
serum by precipitation with lead acetate, washing with water,
suspending the precipitated lead compound in water, and decom-
posing it with carbon-dioxide ; then, by nitration, a very cloudy
solution of albumin is obtained. The albumin may now be pre-
cipitated from this solution by the addition of alcohol which in
time coagulates it. It is not precipitated by weak mineral acids
in small quantity; but large quantities of acid precipitate it
immediately, nitric acid acting most strongly. It forms a yellow,
elastic, transparent substance which, when perfectly dry, can be
heated to 100 F. (37'7 C.) without change. The substance to
which the clotting of blood is due is termed fibrin. It is insoluble
in water, sparingly soluble in dilute acids and alkalies and in
neutral saline solutions. It may be obtained by washing blood-
clots, or more readily by stirring with a bundle of twigs blood
just shed, before it has had time to clot. The fibrin, which
adheres in layers to the twigs, may then be stripped off and
washed till perfectly white.
Egg* albumin or white of egg differs from serum albumin by
gradually giving a precipitate when agitated with ether, whilst oil
of turpentine coagulates it. A characteristic between serum and
egg albumin is that the former is easily dissolved by nitric acid
whereas the latter is only dissolved with difficulty therein. The
so-called vitellin contained in solution in the yolk of egg is a
mixture of albumin and casein. If a drop of egg albumin is
allowed to fall into a saturated solution of resorcinol, the drop of
albumin, at first transparent, becomes gradually opaque, and
finally white like a hailstone. It gradually falls through the
liquid, lengthens itself out to a band, becomes broader and
PROTEIDS OR ALBUMINOIDS AND ENZYMES 83
broader, and finally reaches the bottom. It has the appearance of a
bacteriological culture. If the liquid is now shaken it falls to the
finest powder, and is so disseminated in the froth that it appears
to have dissolved. The s'ame effects are produced however dilute
the egg albumin may be.
Casein OP legumin, sometimes termed alkali-albumin, or
albuminate, according to whether the substance is derived from
animal or vegetable sources.
An example of casein is the flocculent substance which separates
when milk becomes acid, whilst legumin occurs in peas, beans, etc.
Casein occurs most plentifully in the milk of animal feeders,
and is best obtained from milk by precipitating with crystalline
magnesium sulphate, filtering and washing with concentrated
solution of sodium chloride, and dissolving the precipitate in
water; the butter is then filtered off, and the clear solution
precipitated by dilute acetic acid. Dried casein and albuminate
are yellow, transparent, and hygroscopic ; they swell in water but
do not dissolve. They dissolve easily in alkaline water when
placed in it in a flocculent state. The precipitate which forms,
on neutralising the alkaline solution, dissolves easily in an excess
of acetic or hydrochloric acid.
By fusion with potassium hydrate, casein yields valeric and
butyric acids, besides other products.
Plant albumin or gluten is a substance analogous to the
fibrin previously described ; it occurs as an insoluble substance in
plants, especially in the seeds of cereals and grasses.
When wheat flour is lixiviated with water, a tough, coherent,
elastic mass is left behind, which can be pulled out into strings.
This is the gluten, or the body which gives the coherent character
to the dough, and the presence of which confers the property of
enabling it to yield a light, porous bread. Gluten cannot be
obtained in this way from the meal of any other grain. It is
insoluble in water, becomes dark by exposure to the air ; whilst
dried at a low temperature, it assumes a yellowish-brown colour
and becomes horny, and when treated with strong alcohol it
assumes an earth-like appearance. It may be dissolved by
hydrochloric acid and dilute alkalies, and is precipitated from
these solutions by mineral salts and acetic acid.
MOLECULAR CONSTITUTION OF THE PROTEIDS.
All proteids contain the elements carbon, hydrogen, nitrogen,
and oxygen, whilst occasionally they contain sulphur and phos-
84 THE BREWER'S ANALYST
phorus. Our knowledge of their composition is, however, very
imperfect, and at present it is assumed that their molecule is
extremely complex.
Stohmann and Langbein assert that the formula of crystallised
proteid is C 720 H 113 N 218 S 5 248 , equivalent to a molecular weight
of 16,954, whilst Sabanejeff obtained a molecular weight of 15,000
by Raoult's cryoscopic method. This method, however, is admitted
to be inapplicable to the accurate determination of the molecular
weights of colloid bodies, hence the figures cannot be accepted as
of definite value, but merely as a confirmation of the high
molecular weight of these bodies. Many investigators have
obtained compounds of proteids with inorganic salts; thus a
copper salt obtained approximates to the formula
whilst with magnesium and other salts the formula
has been indicated.
EFFECTS OF HYDROLYSIS ON THE PROTEIDS.
By the action of certain hydrolysing agents such as superheated
steam, dilute mineral acids, caustic alkalies or enzymes, the latter
of which are dealt with hereafter, the large proteid molecule is
split up into much smaller and less complex molecules. From a
study of these we have obtained some general knowledge as to.
the nature of the molecular groups which enter into the composi-
tion of the proteids. When the proteids are acted upon by
enzymes, the splitting-up process does not extend nearly so far,
the molecules of the bodies produced being much nearer in size
to that of the original proteid molecule.
Of such a nature are the proteoses and peptones.
The nature of the hydrolysis may be conveniently stated as
follows :
Proteid Albumin.
Proteoses.
Peptones.
I
Amides.
All the amides are of a crystalline nature and eminently diffus-
ible in plants ; and it is extremely probable that the amides in
the living plant form a portion of the materials from which the
PROTEIDS OR ALBUMINOIDS AND ENZYMES 85
proteids are constructed, the amides themselves being probably
produced by a combination of the deoxidation products of the
chlorophyll cells with nitrogen, derived from the nitrates and
ammonia contained in tire fluid contents of the cells. Whether
this conjecture is right or wrong, we know that numerous amide
bodies and also various products resulting from their hydrolysis
exist in plants. We are also aware that by the action of acids,
alkalies, or steam, proteids or albumins may be decomposed to
proteoses and amides, and that the latter bodies are further
hydrolysed. Thus by the action of boiling hydrochloric acid to
which a little stannous chloride is added, amides produce, more
or less, the following substances :
Leucine.
Tyrosine.
Aspartic acid.
Glutamic acid.
Glutaminic acid.
Lysine.
Arginine.
Histidine.
Lysatine.
When barium hydroxide is used as the hydrolysing agent, in
addition to the formation of the above-mentioned products, much
ammonia and carbon-dioxide are evolved ; and these gases are
given off in the proportion of one molecule of water and one of
VTTT
urea, CO** 2 + OH 2 = C0 2 + 2NH 3 .
Taking the principal amide substances, we have the following:
Leucine or ctmido-caproic add.
CH 3 , /NH 2
C 6 H 13 N0 2 = >CH-CH 2 -CH<
CH 3 / \COOH.
This amide is usually the normal product in every energetic
decomposition of proteid matter ; it is obtainable in considerable
amount by the hydrolysis of horn by acids, and by the action of
trypsin upon most proteids. It is found in germinating seeds
and is present in germinated barley and in malt worts. In a
state of purity it consists of brilliant, silvery- white plates,
which melt at 338 F. (170 C.). It is soluble in water, arid
its aqueous solutions are dextro-rotatory. It is only slightly
soluble in alcohol. It has been prepared synthetically. When
86 THE BREWER'S ANALYST
treated with nitrous acid it yields up the whole of its nitrogen
thus : ^
C 6 H 8 N0 2 + HN0 2 = C 6 H ]2 O 3 + OH 2 + 2N
Leucine. Nitrous Hydroxy- Water. Nitrogen.
acid. caproic acid.
Tyrosine or paraliydroxy-phenylamido-propionic acid
/OH /NH
C 9 H n N0 3 = C 6 H/ CH<
\CH 2 \COOH
is also produced in the decomposition of all proteids, with the
exception of gelatine, and has frequently been detected in
germinated seeds. When pure, it crystallises in brilliant silky
needles which are not readily soluble in water, and insoluble in
alcohol. An aqueous solution is Isevo-rotatory, but a dextro-
rotatory modification is known.
It is found in the liver and other organs, and among the
excretory products of yeast, and frequently accompanies the
decomposition of proteids by the putrefactive action of bacteria.
Treated with nitrous acid, it yields up nearly the whole of its
nitrogen.
Asparaglne or amido-succinamide.
/ CH \
C 4 H 8 N 2 3 = COOH< >CH 2 -CON H 2 .
So called because it was first found in asparagus sprouts. This
substance, although probably not resulting from the breaking
down of proteids by proteohydrolysts, is of great importance,
since it is found in considerable amount in many plants and
germinating seeds. It has not yet been isolated from malt, but
occurs in considerable quantity in the rootlets. It is supposed
that the formation of this compound in living plants is, in reality,
a result of synthesis rather than decomposition ; that is to say,
as previously mentioned, it makes an early stage in the building
up of the complex albuminoids rather than a final stage in the
retrograde decomposition by proteolysis.
Although the existence of asparagine in malt and wort is
uncertain, there is little doubt that its presence would be of
considerable benefit. The extraordinary stimulating effect of this
substance upon the activity of diastase has been investigated by
Effront and Fernback, and its high value as yeast nutriment has
been fully demonstrated by Stern.
In a state of purity it forms large colourless crystals, soluble in
PKOTEIDS OR ALBUMINOIDS AND ENZYMES 87
water, but insoluble in alcohol. Its aqueous solutions are laevo-
rotatory, its specific rotatory power being [o] D =-6 % 23. A
dextro-rotatory asparagine which rotates the same angle in the
opposite direction has, however, been found in tares. The dextro-
rotatory body has a distinctly sweet taste; the laevo-rotatory is
almost tasteless. When heated with dilute acids, asparagine is
readily transformed into aspartic acid and ammonia, thus :
C 4 H 8 N 2 8 + OH 2 = C 4 H 7 N0 4 + NH 3 .
Asparagine. Water. Aspartic acid. Ammonia.
When acted on by nitrous acid, it yields half of its nitrogen in
the gaseous state as follows :
C 4 H 8 N 2 8 + NH0 2 - C 4 Hg0 5 + NHg + 2JS T .
Asparagine. Nitrous Malic Ammonia. Nitrogen,
acid. acid.
A method for the estimation of asparagine and the amides
generally has been based on this reaction by Sachasse. 1 Aspara-
gine is precipitated by mercuric nitrate, and the compound so
obtained may be decomposed into asparagine and mercuric
sulphide by the action of hydrogen sulphide.
AspartlC acid or amido-sucdnic add.
C 4 H 7 N0 4 = CH/
pw \COOH
UH 2 ,
\COOH.
This is the crystalline body previously referred to ; it is slightly
soluble in water, rotates the polarised ray to the left or right,
according as the asparagine from which it is obtained is laevo- or
dextro-rotatory. Treated with nitrous acid, it yields up the whole
of its nitrogen thus :
C 4 H 7 N0 4 + HN0 2 = C 4 H 6 B + OH 2 + 2N.
Aspartic Nitrous Malic Water. Nitrogen,
acid. acid. acid.
Among other amide compounds resulting from the decomposi-
tion of the proteids, the following may be enumerated, which have
a more or less important bearing upon the subject :
Glutamic acid or amido-gluiaric add.
/\
4 = CH 2 < \COOH
\CH 2 -COO
Agricult. Chem., 390.
88 THE BREWER'S ANALYST
Glutaminie acid.
^5H 10 N 2 O a ^ A j. 2 v x
\CH<
CH 2 -CONH 2
K 2
COOH.
And the hexone bases :
Lysine or diamido-caproic acid.
C 6 H 14 N 2 2 = CH 2 NH 2 -CH 2 -CH 2 -CH 2 -CH/
\COOH
a dextro-rotatory substance from hydrolysis of casein.
Arginine or diamido-valeric acid.
/NH 2X ,NH 2
C 6 H 14 N 4 2 = NH = C< >CH 9 -CH 2 -CH -CH<
\NH / X COOH.
Histidine. C 6 H 9 N 3 2 .
Lysatine. C 6 H 18 N S 2 .
In addition to the above compounds, glycocoll (amido-acetic acid)
CH 2 <^ sometimes results from proteolytic decomposition,
\COOH
and has been detected in many plants.
Besides the important amide products, resulting from the
decomposition of the proteids by hydrolysis, either by acids or
enzymes, there are numerous bodies which result from the
breaking down of albuminoid substances by the aid of living
organisms ; these are frequently excretory products such as :
Xanthine . . . C 5 H 4 N 4 2 .
Sarcine . . . C 5 H 4 N 4 0.
Guanine . . . C 5 H 3 N 5 0.
The above and other xanthine bases are found among the
excretory products of yeast and micro-organisms of other
description. In addition to these or similar substances, besides
the normal products of proteohydrolysis, many pathogenic
organisms form either products of a phylacteric nature, such as
protective serums, or of a poisonous nature, such as the toxins,
which, together with the ptomaine* formed by certain kinds of
putrefactive bacteria, partake of the nature of alkaloids.
CHEMICAL REACTIONS OF THE PROTEIDS.
The proteids give the following characteristic reactions, which
may readily be observed with a solution of egg albumin, made by
PROTEIDS OR ALBUMINOIDS AND ENZYMES 89
mixing a small quantity of white of egg, which contains about 12
per cent, of albumin, with water, and filtering.
Precipitation by Nitric Acid. When strong nitric acid is added
to an aqueous solution of any of the proteids, a white precipitate
forms, which turns yellow on heating the liquid. The addition of
ammonia to the mixture, after it has become cold, causes the
yellow precipitate to become orange-coloured.
Biuret Reaction. On adding a few drops of a dilute solution of
cupric sulphate to an aqueous solution of a proteid, and after-
wards a few drops of a strong solution of caustic soda, a colour is
developed which varies with the different classes of proteid. The
proteids give a violet colour ; the proteoses, a reddish-violet ; the
peptones, a rose-red.
Millon's reagent l yields a white precipitate which becomes
reddish on boiling the fluid.
Evolution of Ammonia. The proteids when strongly heated
evolve ammonia, produced under the destructive action of heat.
The ammonia may be recognised hy its changing the colour of a
piece of moist red litmus paper to blue. A smell resembling that
of burnt hair is also given off during the heating.
Formation of Cyanides. The proteoses, when heated with
metallic sodium, yield sodium cyanide. The presence of this
compound can be detected by extracting the mass with water,
adding a few drops of a solution of ferrous sulphate containing a
little ferric sulphate, and digesting for a short time. On the
addition of hydrochloric acid a blue or bluish-green colour is
produced if proteids are present.
MEMBEES OF THE PROTEID GROUPS.
By means of the solvent power of various saline solutions it
has been found possible to isolate the proteids from the sub-
stances with which they are associated, and to effect a fairly
complete separation of the various members of the proteid
groups from one another by reason of the further property
possessed by certain salts of throwing out of solution certain
members of the groups when the solution is saturated with the
particular salt.
This latter process is known as "salting out," and by the
1 Millon's Reagent. Prepared by gently warming mercury with an
equal quantity of strong nitric acid till it dissolves, then diluting the liquid
with twice its bulk of water, and leaving the precipitate to settle. The clear
supernatant liquid is the reagent.
90 THE BREWER'S ANALYST
employment of this method the various plant proteids have been
divided into the following groups :
Albumins. Soluble in water, coagulated by heat.
Gliadin and Hordein. Slightly soluble in water, readily soluble
in 70 per cent, alcohol.
Glutenin. Slightly soluble in hot water and hot alcohol,
soluble in O'l per cent, solution of caustic potash and in 0'2 per
cent, hydrochloric acid ; insoluble in saline solutions.
Gloubulins- Vitellins. Insoluble in water, soluble in dilute
saline solutions, coagulated in great part by heat.
Gloubulins- Myosi7is. Insoluble in water, soluble in dilute
saline solutions, precipitated by sodium chloride, coagulated by
heat.
All these bodies, excepting the latter (gloubulins), are obtained
in an amorphous condition, in which state they probably exist in
plants. Many of the gloubulins have been obtained in a crystalloid
form, and to some extent exist in this condition in seeds.
THE PROTEIDS OF BARLEY.
Ritthausen l succeeded by fractionation with alcohol in
differentiating three proteid bodies from wheat-flour, viz., gluten-
fibrin, gliadin, and mucedin, and a fourth, gluten-casein, which
was insoluble in alcohol but soluble in dilute alkali. He con-
sidered that these four bodies constituted the gluten of wheat,
and that it was the gliadin which formed the binding material.
This body was found to be absent in the flour of those grains
which left no gluten behind on washing.
Ritthausen also considers that these are the bodies belonging
to the gluten group in barley, viz., gluten-fibrin, gluten-casein,
and mucedin.
Osborne 2 finds that there are only two : hordein, which is
apparently identical with Ritthausen's mucedin, but which has
almost the same physical and chemical properties as the gliadin
obtained from wheat, though it differs from it in composition ; the
second being the insoluble proteid which it was found impossible
to isolate.
Mulder 3 found a barley to contain 6 per cent, of albumin and
plant gluten ; he obtained the latter by extracting the ground
barley with hot alcohol.
Von Bibra 4 considers that the proteids of barley are albumin,
1 Die EiweissJcdrper. a Jnl. Amer. Chem. Soc., xv. 392.
3 Ann. Chim. et Phys. , 306. 4 Die Getreidearten, 204.
PROTEIDS OK ALBUMINOIDS AND ENZYMES
91
plant gluten, and casein, but gives no particulars concerning
these substances.
Kreusler found that an aqueous extract of ground barley con-
tained an albumin which '"coagulated on boiling, and that hot
75 per cent, alcohol dissolved a substance which could be sub-
sequently separated into three proteids gluten-casein, gluten-
fibrin, and mucedin, which were supposed to be identical with
the bodies having the same names, which Ritthausen had isolated
from wheat.
According to Osborne, 1 to whom we are indebted for an
elaborate and extensive series of investigations on the proteids of
various grains and seeds, barley contains the following proteid
bodies :
Per cent.
Leucosin (albumin) . . 0*30
Proteose ) , .g^
)
Edestin (globulin)
Hordein
Insoluble proteid .
Total
4-00
4-50
10-75
whilst the average percentage composition of a large number of
analyses gave the following :
Carbon.
Hydrogen. Nitrogen.
Sulphur.
Oxygen.
Leucosin .
Edestin .
Hordein .
52-81
50-88
54-29
6-78 16-62
6-65 18-10
6-80 17-21
1-47
2232
^/
24-37
0-83
20-87
Insoluble proteid
Unknown.
THE PROTEIDS OF MALT.
During the process of malting, the proteids of barley undergo
considerable modification, a large portion which are insoluble in
water becoming soluble as the barley germinates. This arises
chiefly from the breaking down of the proteids into proteoses.
The proteids of malt have been investigated by Osborne and
1 Report of the Connecticut Agricultural Experimental Station, 1892.
92 THE BREWER'S ANALYST
Campbell, 1 who, by employing similar processes to those which
they adopted in their investigations on the proteids of barley,
obtained the following bodies :
Bynedestin. A globulin, soluble in dilute solutions, and
therefore passing into the aqueous extract of malt. It appears
to replace the original edestiu of the barley, from which it differs
in composition, since bynedestin contains about 2 per cent, more
carbon and 3 per cent, less nitrogen. Its percentage composi-
tion is
Carbon .... 53-19
Hydrogen .... 6"69
Nitrogen .... 15*68
Sulphur . . . .1-25
Oxygen . . . .23-19
Leucosin. Identical in composition and properties with the
albumin of the same name contained in barley.
Protoproteose 1. Has the same composition as leucosin,
from which it is impossible to effect a complete separation. The
proteose is precipitated from its aqueous solution by adding an
equal weight of alcohol.
Protoproteose 2. Less readily precipitable than No. 1, by
alcohol, its percentage composition being
Carbon .... 5O63
Hydrogen . . . 6 -67
Nitrogen .... 16"69
Oxygen and sulphur . . 20*01
DeutCPOproteOSe. A body inseparable from non-proteid
impurities.
HetePOproteOSe. A substance found in extremely small
amount.
Bynin. A body insoluble in water or saline solutions, but
readily soluble in dilute alcohol, its percentage composition
being
Carbon . . . .55-03
Hydrogen . . . 6 -67
Nitrogen . . . . 16 '26
Sulphur .... 0-84
Oxygen . . 21 '20
Insoluble Proteid. This, which amounts to about 3 '80 per
cent, of the total proteid matters, is insoluble in water, saline
1 Report of the Connecticut Agricultural Experimental Station, 1896, 239.
PROTEIDS OR ALBUMINOIDS AND ENZYMES 93
solutions, or alcohol ; and consequently it is impossible to study
its composition or determine its properties. A sample of malt
which contained altogether 7 '84 per cent, of proteid matters,
yielded the following quantities of these substances, as far as they
could be separated :
Per cent.
Proteids, insoluble in salt solution or alcohol . 3'80
Bynin, soluble in dilute alcohol . . . .1*25
Bynedestin, leucosin, and proteoses (coagulable) . 1 -50
Bynedestin, soluble in water and salt solution
(uncoagulable) . . . . . . 1'29
Total proteids . . . 7 '84
These results show that during germination the proteids of
barley undergo extensive changes before acquiring the properties
of proteoses ; that hordein disappears, and an alcohol-soluble body
of entirely different composition takes its place ; that edestin
also disappears, and a new globulin is formed very different both
in composition and properties.
The albumin, on the other hand, appears to be unchanged in
character, but its quantity is increased. It is to be noted that
hordein and edestin are both replaced by proteids much richer
in carbon and poorer in nitrogen.
ENZYMES OR HYDROLYSTS.
Enzymes or hydrolysts exist in all living organisms whether
of animal or vegetable origin, and are remarkable nitrogenous
bodies either actually albuminoids or very closely allied to them.
There are numerous varieties, each having its special correlative
alimentary principle or group of principles, on which, under
certain conditions (an absolutely necessary one being the presence
of water), it is capable of acting. Diastase, for instance, acts on
amylaceous substances and cane-sugar ; whilst pepsin and trypsin
act only on the azotised principles. The emulsive ferment of the
pancreas is only capable of acting on fatty bodies, and the
inversive ferment of yeast and of the small intestine has no
activity except on cane-sugar.
These nitrogenous bodies are often spoken of as the " unorganised
ferments " or " enzymes," * and the transformations they effect
1 The word "enzyms" was first proposed by Ktihne. Roberts afterwards
adopted the word into English with a slight change of orthography, terming
it "enzymes."
94 THE BREWER'S ANALYST
" fermentative processes." In 1 890, however, Armstrong suggested
more scientifically correct terms, viz., as in the changes brought
about by these bodies water is almost invariably assimilated or
added to the molecule of one or both of the newly formed
substances, the process is one of, and should be designated,
" hydrolysis," and the agents concerned in the action " hydrolysts."
Thus by combining with the word " hydrolyst," the name of the
substance on which each particular enzyme acts, we obtain a
distinctive name for each class. Thus the enzymes which act
upon starch are now called amylo-hydrolysts ; those that act on
proteids, proteo-hydrolysts, etc.
CHEMICAL COMPOSITION OF THE ENZYMES.
It is doubtful whether any of the preparations of .the enzymes
obtained by different investigators have been of a sufficient degree
of purity to permit of accurate determination of their chemical
composition.
Lintner, working with the diastase of malt, obtained a solution
possessing a high diastatic power having the following com-
position :
Carbon . . . .46*66
Hydrogen . . . 7 '35
Nitrogen . . . 10 '41
Oxygen . . 34*46
Sulphur .... 1-12
A substance having this composition differs from albumin, to
which the enzyme bodies are generally closely allied, albumin
on analysis giving the following percentage composition :
Carbon .... 53*02
Hydrogen . .6*84
Nitrogen . . . 16*80
Oxygen . . 22*06
Sulphur . . . .1*28
At first sight one would be disposed to consider diastase as
a substance differing in a marked degree from albumin. Osborne,
however, who has made a very close study of the albuminoid
constituents of cereals, isolated a diastase having a much higher
diastatic power than Lintners preparation, its diastatic power
being equivalent to 600 upon Lintner's scale.
The composition of this body, which is undoubtedly one of
PROTEIDS OR ALBUMINOIDS AND ENZYMES
95
the purest preparations of the enzymes which has been obtained,
is as follows :
Carbon
Hydrogen
Nitrogen
Oxygen
Sulphur
52-50
6-72
16-10
22-78
1-90
a- body of this percentage composition closely agreeing with the
analysis of albumin already given.
Osborne further found that this diastatic preparation had a
very close resemblance to leucosin, an albumin which he had
previously isolated from barley, wheat, rye, and malt.
Other preparations of diastase and enzyme substances have
been made by different investigators, the chief of which are in-
cluded in the following table by Enron t, " Les enzymes " :
Carbon.
Hydrogen.
Nitrogen.
Sulphur.
Ash.
Malt diastase
45-68
6-90
4'57
6 08
j j j j
47-57
6-49
5-14
...
3-16
Invertase .
43-10
7-80
4-30
...
6-10
>
43-90
8'40
6 00
0-63
3 )
40'50
6-90
9 30
...
Ptyalin .
43-10
7-80
11-86
6-10
Trypsine .
5275
7-50
16-55
17-70
Pepsine
53-20
670
17-80
...
Pancreatin
43-60
6-50
13-81
0-88
7-04
Emulsin
43-06
7'20
11-52
1-25
48-80
7-10
14-20
1-30
...
It will be seen from the foregoing table that considerable
differences exist between the various enzyme bodies, these differ-
ences being due to imperfectly purified substances. The diffi-
culty of obtaining these bodies free from ash and carbo-
hydrate matters, with which they are always contaminated, being
the cause.
All the enzymes when in solution are extremely susceptible to
elevated temperatures, their power being weakened, and if the
heating be continued they are wholly destroyed, the destruction
being usually accompanied by separation of the albuminoid in an
insoluble form, since many of them appear to belong to the group
of coagulable proteids.
96 THE BREWER'S ANALYST
ENZYME GROUPS.
The enzymes may be divided into the following seven groups,
in which they are arranged according to their respective specific
actions :
GROUP I. Diastatie Enzymes :
Diastase of secretion (malt) . } , . ,
, ( . \ Convert starch into mal-
Translocate diastase (barley) . ,
Ptyalm (saliva) . . . '
Glucase (maize) /Converts starch finally
( into glucose.
GROUP If. Cyto-hydrolytic Enzymes:
Cytase (malt) . . . . | Transform cellulose into
Enzymes of seeds in which the r sugars, such as man-
reserve material is cellulose . ' nose, xylose.
GROUP III. Pectin Enzymes:
Enzymes which convert pectinous substances into vege-
table jelly.
GROUP IV. Inverting 1 Enzymes :
Invertase (yeast) . . . ) Convert cane-sugar into
Invertase (malt) . . .1 invert sugar.
Maltase or glucase (yeast) . ) Transform maltose into
Enzymes of the small intestine J glucose.
Enzymes of yeast which degrade the intermediate dextrins
into maltose ; these are especially present in wild
yeasts.
Enzyme of Kephir . . . Inverts milk-sugar.
Probable enzyme of germinating ) Converts maltose into
barley . . . . J cane-sugar.
GROUP V. Proteolytie Enzymes :
Enzymes of malt and other ^
vegetables (sometimes called Convert P roteids into
peptase), but which have not f P roteose ' peptones,
i j ,, ., , . i , i and amides,
yet been definitely isolated . J
Trypsin (pancreas) . . | Amido acids and hexone
I bases.
PROTEIDS OR ALBUMINOIDS AND ENZYMES 97
j Converts proteids into
Pepsin (stomach) . . proteosesand peptones,
' but not into amides.
Peptonising ferments secreted by many bacteria.
GROUP VI. Glucosidal Enzymes :
Splits up amygdalin into
oil of bitter almonds,
Jijniulsin (bitter almond) . . i , , . .-,
hydrocyanic acid, and
water.
Many other enzymes which have the power of hydrolysing
glucosides.
GROUP VII. Zymase (yeast) :
Splits up sugar into alcohol and carbon-dioxide.
ACTION OF THE PROTBOLYTIC ENZYMES ON THE PROTEIDS.
From the preceding list showing the various groups of enzymes,
we have, amongst others, those of animal origin, which act upon
insoluble proteids as follows :
1. The pepsin group, which act upon albumins, degrading them
to proteoses and peptones.
2. The trypsin group, which act upon albumins, resolving them
beyond the peptone stage, with the formation of simpler com-
pounds, viz., amido acids and hexone bases.
There is no doubt that proteolytic enzymes exist in plants,
since, as already mentioned, before the reserve materials stored
up by plants can be made available for the operations of nutrition,
they must first be converted from their inert and mostly insoluble
state into a state of solution and adaptability to circulate in the
nutritive fluid of the plants.
Group-Besanez, in 1874, 1 was the first to conclude that a
proteolytic enzyme existed in germinating barley, and he con-
sidered he had extracted it not only from barley, but also from
tares, hempseed, and linseed.
It is extremely doubtful, however, whether or not he detected
such enzyme, and in any case his method for detecting the pro-
ducts of its action is open to criticism. A powerful enzyme of
this nature has, however, been lately isolated in a fairly pure
state from the latex of the tropical plant Carica papaya, so that
proof is no longer wanted of its existence in plants, although it
has not yet been isolated from barley or malt. Shortly after
1 Berichte, 1874, 7, 1478.
7
98 THE BREWER'S ANALYST
Group-Besanez's investigations, Neumeister, 1 working with ex-
tracts prepared from germinating barley and green malt, obtained
products from blood fibrin which he considered exhibited char-
acteristic albumose and peptone reactions. Here the matter rested
until 1899, in which year Lazynscki 2 disputed the existence of
a proteolytic enzyme. In 1900, however, Fernback and Hubert 3
concluded that they had discovered it, and then followed other
investigations by Windisch and Schellhorn, 4 Petit and Labourasse, 5
Weiss, 6 and finally Schidrowitz, 7 all of which endeavoured to prove
the existence of a proteolytic enzyme in barley and malt.
The tests of these various investigators, however, have no real
value, and up to the time of writing no proteolytic enzyme has been
satisfactorily isolated from barley or malt, and on this account
there is and will be, from time to time, considerable controversy
as to whether barley or malt contains such an enzyme and whether
any peptonising action really takes place during mashing.
When germination commences in the grain of barley, it is
necessary that the starch stored up in its endosperm should be
able to travel to the growing germ. This is first effected by an
enzyme or amylo-hydrolyst (the translocation diastase) already
present in the seed, afterwards by another hydrolyst (ordinary
diatase) which is formed in considerable quantity during
germination. 8 In like manner the insoluble proteids in the grain
are, to a great extent, rendered soluble and diffusible, but in what
manner has not yet been settled, although from what has been
stated there is strong evidence of the existence of proteid-
hydrolysts both in barley and malt in spite of the fact of their
non-extractability therefrom.
As, therefore, we are unable to obtain a single proteolytic enzyme
from barley or malt, we have to rest content with a knowledge of
the action of the animal proteolytic enzymes, pepsin and trypsin,
which can be obtained in an almost pure state from the stomach
and pancreas of animals, and surmise, from their action, what
action takes place during the germination of barley and the
peptonisation of the proteids of malt during mashing.
Wort must contain proteid bodies of a nature readily assimilable
1 Zeit.f. Biologic, 30 (94), 447. 2 Zeit. f. d. gesammt. Brau., 22, 71.
3 CompL Rend. (4). 4 Wocliensch. Brauw. (1900), 17, 334-452.
5 Compt. If end., July 5 and 6, 1900.
6 Zeit.f. phys. Chem., 31, 78-97, and Zeit. ges. Brauw., 1903.
7 Jnl. Fed. Inst. Brewing, 1903, 361.
8 "Researches on the Germination of some of the Gramineae," Jnl. Chem.
Soc. Trans., 1890,458-528.
PROTEIDS OR ALBUMINOIDS AND ENZYMES 99
by yeast, or the yeast would speedily become weak for want of
food and as a consequence become incapable of properly ful-
filling its functions. The albumin and globulins which occur in
barley seem completely indiffusible, but the proteoses and amides
are very highly diffusible.
These facts therefore show that the diffusible and assimilable
bodies requisite for yeast nourishment are yielded by the proteo-
lysis of the proteids originally contained in the barley, effected for
the most part during its germination, and afterwards, to a slight
extent, during the mashing process. Pepsin acts best in slightly
acid media, preferably 2 per cent, hydrochloric acid, and the most
favourable temperature for its action is 100 F. (37*7 C.), the
" blood-heat " of most mammals. When coagulated egg albumin
or other insoluble proteid is added to an acid solution of pepsin,
and maintained at a temperature of 100 F. (37'7 C.) for some
hours, the process of digestion is imitated, solution of the proteid
taking place accompanied by a degradation of the albumin mole-
cule to proteose and then peptone, the proportion of the latter
body being dependent upon the time of digestion.
Pepsin is incapable of degrading proteids beyond the peptone
stage, so that peptone must be considered the final product of its
action, although there is evidence that other bodies besides
proteoses and peptones are formed. These secondary products
result from the action of pepsin upon a portion of the peptone,
and although closely allied to this group, do not give the
characteristic reactions of these bodies.
According to Dr Sykes, 1 "The proteid molecule consists of two
distinct groups or radicles, from which the various products of
proteolytic action are derived. The following schematic arrange-
ment will, without going into too minute distinctions, give a
general idea of the series of changes :
Proteose
Deuteroproteose
Pro
Synt
beid
ilbumin
Anti-f
I
Peptone
IHetroproteose
Deuteroproteose
Peptone.
Principles and Practice of Brewing, 167-168.
100 THE BREWER'S ANALYST
"The great distinction between these two groups, which are
called the hemi- and an ti -groups, and which appear to exist in
about equal quantities, is that the peptone of the former can be
further broken down by the action of trypsin into a number of
amide bodies, whilst the peptone of the latter cannot be so
broken down. In every digestion a variable quantity of a
substance is left undissolved, which is called anti-albumin ; it is
extremely resistant to the further action of the proteolytic
enzyme, but, by treatment with strong solution of pepsin and acid,
may be partially converted into anti-deutero-albumose, and finally
into anti-peptone."
Sykes proposes l the following process for the estimation of the
proteids in malt : " The malt is extracted with cold water,
filtered, and the albumin in the nitrate coagulated at a tempera-
ture of 140 F. (60 C.). The coagulum is filtered off and
weighed. The filtrate is then boiled for a short time, when a
second precipitate forms, which is filtered off and weighed. This
is considered to represent the globulin, but from the recent
experiments of Osborne, it is extremely doubtful if all the globulin
can be separated by boiling.
"The filtrate is now evaporated to small bulk and saturated with
ammonium sulphate, when a precipitate consisting of the proteoses
(and probably some globulin) comes down. This is filtered off,
washed with saturated solution of ammonium sulphate, dried and
weighed, the weight of the ammonium sulphate, adhering to the
precipitate and filter paper, being determined and deducted. The
filtrate from this precipitate is then diluted with an equal
quantity of water, and solution of tannic acid added. This pre-
cipitates peptone, if it be present; but no precipitate of any
moment has ever been observed, which leads to the conclusion that
real peptone does not occur in malt."
Szymanski considered that he had separated peptone from malt,
but from the process he adopted for its isolation, the substance
which he obtained and mistook for real peptone was evidently
deuteroproteose.
Sykes, experimenting on the proteids of malt, was never able
to detect a hetroproteose on dialysing the precipitate thrown
down by ammonium sulphate.
A precipitate was always yielded on saturating malt extract with
sodium chloride and adding a little acetic acid, leaving the body in
solution which Szymanski mistook for peptone. In all probability,
therefore, the two proteoses are proto- and deutero-proteose.
1 Jnl. Fed. Inst. Brewing, vol. jv, 173.
PROTEIDS OR ALBUMINOIDS AND ENZYMES 101
DIASTASE.
The diastatic enzymes^ are of the greatest importance and
interest in brewing and malting, from the fact that they embrace
the numerous bodies which have the power of liquefying and
saccharifying starch.
Of this group, malt diastase is the best known, for the reason
that it has received the most attention from scientific investigators.
In 1811, Kirchoff found that the albumin contained in barley
is capable of acting upon soluble starch and producing a
cry stalli sable sugar similar to that produced when starch is
boiled with dilute acid ; and he noticed that this action is greatly
intensified if the barley is germinated or malted.
Payen and Persoz, in 1833, were the first, however, to isolate the
soluble " ferment " and to identify it as the principle which is
capable of exercising such a powerful action upon starch. They
gave it the name diastase, which it still retains. This name was
given on account of the agent's supposed property of separating
the interior of the starch granule (granulose) from its outer
membrane (amylo-cellulose), but, as is now well known, this is
not strictly true, and furthermore erroneous ideas prevailed as to
the nature of the sugar produced by its action.
The isolation of diastase from malt was undoubtedly a most
important discovery, but little further advance was made until
O'Sullivan, in the course of his researches upon the products of
the hydrolysis of starch, again isolated it in a fairly pure state,
and from his study of its specific action under varying conditions
of temperature, evolved many of the principles which are now
well known to govern its action.
Diastase has been detected in almost all animal tissues and
vegetable substances ; thus Payen and Persoz detected its presence
in many germinating seeds, such as wheat, maize, rice, oat, potato
tubers, and in the buds of Ailantkus glandulosa ; Kossmaun and
Kranch found it in foliage and vegetable shoots ; whilst we owe
to Kjeldahl the observation, confirmed by Brown and Morris, of
the presence of diastase, albeit in sparing quantity, among un-
germinated seeds.
Mulder mentions its occurrence in saps which contain starch,
Hansen found it in the sap of Ficus carica, and Gonnermann
detected it in Beta vulgaris. To this we have to add that
Duclaux has shown the common moulds, Aspergillus niger and
PeniciUium glaucum, produce it in abundance ; that Bourquelot has
conducted a complete series of researches, having as its object the
OF THE
IIMIX/PDftlTY
102 THE BREWER'S ANALYST
discovery of diastatic ferments in mould fungi generally, and we
perceive how universal is the occurrence and how widely distri-
buted are amylo-lytic ferments in the vegetable world. Yeast
itself is said to contain a small quantity of diastase, whilst certain
Mucors, also thus endowed, are able to directly ferment starch.
The well-known Tonkin yeast, and even the better known
Koji yeast, the micro-organism employed in the production
of the Japanese beverage, Saki, afford peculiar symbioses of
diastase-producing mould fungi with alcohol-producing saccharo-
mycetes ; in the first-named case a mould, Amylomyces Rouxii,
being associated with a pastorianus yeast, and, in the second
instance, Aspergillus oryzse producing the taka diastase, whilst the
alcohol is formed by the action of some true alcoholic ferment.
Diastase has also been isolated from bacteria, investigators such
as Wood, Wortmann, Perdrix and others having succeeded in
proving its existence in organisms such as the Cholera vibrio, B.
mesentericus vulgaris, B. termo, and in fact practically every
micro-organism is now believed to secrete an enzyme capable of
dissolving starch.
Plants possess three distinct diastases, called respectively
secretion diastase, translocatiou diastase, and cytase; these are
respectively dealt with hereafter under Cytase, where diastatic
action from the maltster's point of view is detailed. From the
brewer's point of view, however, malt diastase is the agent which,
under suitable conditions during mashing, saccharines or trans-
forms soluble starch into dextrin, maltose, and intermediate
malto-dextrins. There is a further part played by diastase which
it is also necessary to remember, viz., the strobiles of the hop
plant contain active diastase which exercises an important
function in " hopping down," the conditioning of cask beer being
brought about to some extent by its hydrolysing action on the
residual malto-dextrins.
O'Sullivan obtained active preparations of diastase by digesting
finely ground malt, preferably low dried, with cold water for
several hours. The mass is then placed in a press and the
resulting extract filtered. On adding 80 per cent, alcohol to the
clear filtrate, a precipitate containing diastase is formed, which is
collected, washed with alcohol and finally with ether, and then
dried as quickly as possible in a vacuo desiccator over sulphuric
acid. During manipulation there is a liability, if the manipula-
tion be unduly prolonged, for the diastase to become converted
into a hard mass which is only partially and with difficulty
soluble in water.
PROTEIDS OR ALBUMINOIDS AND ENZYMES 103
Lintner has devised a better method for preparing diastase
from malt, as follows :
One part of air-dried malt is digested for 24 hours with two to
four parts of 20 per cent, alcohol. The liquid is filtered and
precipitated by two or three times its own volume of absolute
alcohol. The precipitate, rapidly collected on a filter, is crushed
in a mortar with absolute alcohol, filtered, again washed with
absolute alcohol, then with ether, and dried in vacua. When the
operation is performed properly, it yields a white powder which
is readily soluble in water, giving an almost clear solution.
This method of precipitation by alcohol was first employed by
Payen, to whom we owe the earliest important work on diastase.
He had noticed what is also observed with Lintner's diastase, viz.,
that the precipitated substance is not free from mineral matter
(ash). The amount of ash decreases if the diastase is dissolved
in water and precipitated by alcohol, but at the same time it has
lost some of its strength, so that we arrive at this somewhat
paradoxical conclusion, that the purer the diastase, the less active
it is. Purification, instead of increasing, decreases the character-
istic property of diastase, viz., the power of saccharifying starch.
Lintner made the activity of his preparation the standard
(= 100) or basis of comparison.
Osborne, however, as previously mentioned, succeeded in
obtaining preparations of malt diastase, possessing much higher
diastatic power, by precipitating the diastase from cold-water
extracts by means of ammonium sulphate, and by repeated
solution in water and dialysis into alcohol whereby he succeeded
in obtaining diastase practically free from ash and having a
composition approximating very closely to vegetable albumin.
The preparation had a diastatic power of 600, that is, six times as
great as that obtained by Lintner. Diastase prepared by the
foregoing processes is a white or pale yellow coloured substance
readily soluble in cold water, giving slightly opalescent solutions.
Its composition has been determined by various workers, but
considerable difference is shown in the different preparations
obtained, particularly in regard to the nitrogen percentage which
may be taken as a guide to the relative purity of the respective
samples.
Owing to the great diffusibility of diastase contained in malt,
it has been a very easy task for chemists to prepare it from
cold-water extracts of malt, and they have been enabled in this
manner to make a relative determination of the amount of
diastase contained in different malts, and to compare them from
104 THE BREWER'S ANALYST
that point of view. The extract of malt prepared in this way
has been generally employed for the study of diastatic action,
and the researches of Brown and Heron, followed 'by those of
Brown and Morris, have established the laws to which this action
is submitted, to the great benefit of the brewing trade.
These laws are so well known that it is only necessary to briefly
record them.
The maximum energy of diastase, in solution, is obtained at a
temperature slightly below 140 F. (60 C.), immediately above
this temperature it commences to lessen in activity. At 151 F.
(66 C.) this is distinctly pronounced, whilst at 169 F. (76 C.)
its action is almost entirely arrested, and at 177 F. (80'5 C.) its
power is destroyed.
Although, however, solutions of diastase are extremely sensitive
to the influence of heat, solid preparations carefully desiccated
and free from moisture may be heated to 250 F. (121*1 C.)
without their activity being destroyed. This different effect pro-
duced by heat upon the moist and dry substance fully explains
the practical observation of the great loss of diastatic activity in
malt during the first few hours upon the kiln, when the corns
contain a large percentage of moisture, and the relatively slight
influence of high-kiln temperatures when the malt is completely
dry.
Fernback states that the action of diastase, as well as that of
other enzymes, is, within certain limits, favoured by an increase
of the temperature.
The amount of starch transformed by a given quantity of malt
extract increases as the temperature rises. This point is very well
illustrated by Ehrich l :
Temperatures of Time employed for
Saccharification . Saccharification.
F. C. Minutes.
140 60 .... . 120
149 65 ... 25-30
158 70 .. 10
167 75 10
But there is another peculiarity of great importance in the
practice of brewing which, of all enzymes, diastase alone shows.
The amount of fermentable sugar varies with the temperature of
Saccharification. The lower the temperature the greater the
amount of maltose. So that, by employing a definite temperature
1 Der Bierbrauer, 1896, No. 7.
PROTEIDS OR ALBUMINOIDS AND ENZYMES 105
of saccharitication, the brewer has in his hands the means of pro
duoing with a given malt a wort of a given composition, which
will, during the fermentation, yield a given attenuation.
We also find, in the researches of Brown and Morris, a third
point of the greatest practical importance. When an extract of
malt has been heated to a certain temperature, and is afterwards
employed for the saccharification of starch paste at a lower
temperature, the amount of maltose produced is the same as that
which would have been produced at the high temperature to
which the extract of malt had been previously heated. We learn
from this observation that the greatest attention should be paid
to the mashing temperature, as no change at all will be brought
about by the addition of cold water, if the temperature has been
raised too high at a certain period.
Science cannot at present give a satisfactory explanation of
these facts. It was formerly supposed that saccharitication was
produced by two distinct enzymes, one transforming starch into
maltose, the other producing dextrin. The former of these
enzymes was supposed to be destroyed at a lower temperature
than the latter, so that heating the malt extract restricted the
enzyme-producing maltose to a certain extent, and the liquid
obtained produced a wort containing less maltose than was
furnished by the same extract unheated. Different attempts
have been made, especially by Wijsman, to prove the existence of
these two enzymes, but, up to the present, no convincing experi-
ment has been published, and it seems that this hypothesis has
to be abandoned.
In addition to these considerations, it must be stated that
although we know what effect the action of heat has on diastase
from a practical point of view, we have very little information on
the way in which diastase is affected by heat. In a series of
experiments, Fernback noticed that if a solution of pure diastase
(after Lintner's process) be prepared and heated to 140 F.
(60 C.) in a water bath, it will, in a very short time, after less
than one hour, have lost a great part of its activity. This effect
will be observed even if the solution be heated in vacuo, so that
the possibility of an oxidation cannot be admitted, and is out of the
question. This temperature is one of the lowest at which
saccharification can practically operate, so that we are forced to
this conclusion : that, in malt, diastase is accompanied by
substances which confer on it a certain immunity a certain
resistance against the destructive action of heat. It is never-
theless most probable that, during the saccharifying process, a
106 THE BREWER'S ANALYST
part of the diastase undergoes destruction, and from that con-
sideration we understand the great practical utility of a fact
which is most generally observed, viz., that malt contains an
amount of diastase greatly superior to what is necessary for the
transformation of the starch present in the grain.
The twofold function of diastase, namely, the liquefying and
saccharifying, is only found in malt diastase. Kjeldahl showed,
in 1879, that barley diastase has the saccharifying power, but not
the liquefying. This latter power of malt diastase appears to be
closely associated with its ability to slowly dissolve the outer cell
membrane of the starch granule, hence if barley starch be digested
in the cold with a solution of malt diastase, erosion or pitting of
the starch granule occurs, an action which can be distinctly
observed by microscopical examination. Effront has shown that,
if malt or malt diastase is added to a cold-water extract of raw
grain, the power of the diastase is increased ; and that if malt or
malt diastase is added to a raw-grain infusion at a temperature
beyond that at which diastase is destroyed, liquefaction of the
starch takes place, but no saccharification. Although diastase is
capable, however, of exercising a liquefying power upon gelatinised
starch even in the cold, its action upon ungelatinised starch is
slow and negligible from a practical point, this being due to the
resistance offered by the amylo-cellulose which constitutes the
envelope of each starch granule. Hence, it is necessary, in order
that the action of the diastase upon starch granules may be
effective, to conduct the operation at temperatures favourable to
the solution of the cellulose by the diastase.
It has been found that between 130 and 140 F. (54 '4 and
60 C.) the hydrolysis of the cell wall is rapid and complete in
the case of malt and specially prepared raw grain such as maize
and rice flakes or grits, but that in the case of unprepared raw
grain it is necessary to conduct the operation at temperatures
more closely approaching the gelatinisation point of the starch of
the particular cereal employed.
As previously mentioned, then, the saccharifying power of malt
diastase is destroyed at a temperature of 177 F. (85'5 C.). The
liquefying power, however, is not wholly destroyed even up to a
temperature of 220 F. (104'4 C.), and this is, therefore, a
point of considerable importance in the liquefaction of starch
when carrying out raw-grain conversion in specially constructed
vessels.
The nature of the medium in which diastase acts, whether acid
or alkaline, also exerts a very important influence not only upon
PKOTEIDS OR ALBUMINOIDS AND ENZYMES 107
the activity of the enzyme in respect to the amount of starch
hydrolysed, but also upon the nature of the products formed.
Its maximum action is exerted in neutral solutions, comparatively
small quantities of free acid or alkali being extremely prejudicial.
Brown and Morris found that when only slightly alkaline
('005 per cent.) with barium hydrate, sodium carbonate, or sodium
hydrate, its saccharifying power is very much restricted, and
that further increase of alkalinity completely inhibited its power.
The restrictive action of free acid is also well known.
Ling showed that diastatic action is completely arrested by the
presence of *007 per cent, hydrochloric acid and by alkalies.
Other acids, even carbonic, in like manner exert a restrictive
influence. On the other hand, the presence of acid salts,
particularly the phosphates, appears to exert a favourable influence.
Effront has shown that diastatic action is favoured by the
presence of small amounts of asparagin, ammonium acetate,
ammonium chloride, alums of potash and soda, phosphoric acid,
and of ammonium phosphate.
In the presence of 0'4 per cent, of asparagin, the amount of
maltose calculated on the dry substance after one hour's action
at 122 F. (50 C.) was found to be 58'2 per cent., whereas
without asparagin it was only 16*4 per cent. Analogous effects
were observed with the other bodies mentioned, and as the
presence of some of these substances is not excluded, moreover,
is certain, in the extract of malt, we must take them into account,
and we are led to conclude that they play an important part in
diastatic action.
A mash always shows an acid reaction, but this is not due to
free acid, but rather, as has been explained by Fernback, Prior,
and others, to the presence of acid phosphates pre-existing in
the malt or formed by the interaction of the saline constituents
of the mashing liquor and the potassium phosphates of the malt.
From the foregoing details it will be understood why many
conflicting statements have been made by different observers and
investigators as to the absolute energy of diastase. Payen and
Persoz estimate that it is capable of converting 2000 times its
own weight of starch into sugar.
Dubrunfaut, who pursued his investigations on this active
agent up to the time of his death, alleges that malt contains
1 per cent., and that it possesses a power capable of converting
150,000 to 200,000 times its weight of starch. Roberts found
pancreatic diastase to convert. 40,000 times its weight of starch,
and other distinguished observers state that malt contains only
108 THE BREWER'S ANALYST
002 to "003 per cent., and that its converting power is as stated
by Payen and Persoz.
Although the converting power of diastase is very great, a
small quantity being capable of saccharifying a very large amount
of starch, this statement, as will have been seen, only applies
when time, temperature, and concentration are taken into account.
Hence when the time is limited, the converting power of the
enzyme is also limited. In equal intervals of time, and under
definite conditions, the quantity of starch converted is proportional
to the amount of active enzyme present.
This is what is known as Kjeldahl's "law of proportionality,"
and was expressed by him in 1879 as follows: " When equal
volumes of two diastatic solutions are allowed to act upon solutions
of soluble starch under identical conditions of time, temperature,
and concentration, then the cupric reducing power of the tivo solutions,
taken at any given time, is a measure of the relative transforming
powers of the diastatic solutions, providing the cupric reducing
power when calculated as percentage of dextrose is not allowed to
exceed K 25 to 30." In other words, if the amount of maltose
formed does not exceed 40 to 50 per cent, of the starch originally
taken, the relative activities of the two solutions can be deter-
mined from the amounts of maltose formed in a given time, since,
under such conditions, the formation of maltose is proportional
to the amount of diastase present. In the mashing process the
amount of maltose formed is, however, not necessarily proportional
to the diastatic powers of the respective malts, since, in this case,
the diastase is present in excess, and, further, the products of
hydrolysis exceed the proportion above stated.
In 1886 Lintner elaborated a more accurate method for the
estimation of the diastatic power of malt, such method being
based on the same law "the law of proportionality" and
being the one now considered as the most satisfactory. Details
for carrying out the estimation are given hereafter under
" Diastatic Power " in malt analysis.
During the conversion of soluble starch by diastase, the
products formed consist of free maltose and dextrin, and of
intermediate bodies termed malto-dextrins or amyloins, which are
compounds of maltose and dextrin.
Although such intermediate products are undoubtedly formed,
the result of the action of diastase upon soluble starch can always
be expressed in terms of free maltose and dextrin. This "law
of definite relation," enunciated by Brown and Morris, is as
follows : " The products of a starch transformation can always
PROTEIDS OR ALBUMINOIDS AND ENZYMES 109
be expressed in the terms of maltose, having an optical activity of
[a] J3 . 86 =150, and a cupric reducing power K 3 . 86 = 61, and of
dextrin having an optical activity of []j 3 . 86 = 216, and no reducing
power."
Under normal conditions diastase has no further action upon
the maltose and dextrin first formed, but the malto-dextrins are
capable of further hydrolysis, being wholly converted by continued
digestion into maltose, the dextrin content of the malto-
dextrin thus behaving differently to the free or stable dextrin.
GLUCASE OR MALTASB.
The hydrolysis of carbohydrate bodies to the simple hexose
sugar glucose is performed by the group of enzymes termed
glucase or maltase, these designations being to a great extent
synonymous according to the different systems of nomenclature
adopted by different workers. Of the two glucase appears the
better term to employ, since it points to an enzyme capable of
acting upon carbohydrate substances producing glucose, whereas
the designation maltase appears to restrict the term to enzymes
capable of hydrolysing maltose only.
As will be shown later, the enzyme of yeast, which is capable
of decomposing the disaccharide maltose into the simple hexose
sugar glucose preliminary to fermentation, has also an action upon
dextrins, malto-dextrins, and, under certain conditions, hydrolyses
starch; hence it is preferable to employ the term glucase for
this enzyme rather than that of maltase, which was at first
adopted, and is now sometimes employed.
The glucases differ in their nature and properties according to
the source from which they are derived, those which have
received the most attention being derived from maize and yeast
respectively.
Musculus and Gruber were the first to mention the existence
of glucose as being produced by the action of diastase on starch
in addition to the main product maltose. This statement, there-
fore, is tantamount to showing that glucase exists in malt, but
opinions of different investigators are divided as to whether it
does or does not exist in malt; the balance of evidence so far
adduced, however, is in favour of its existence in certain classes
of malt at any rate. Apart from malt, Cuisenier, in 1855, proved
the existence of glucase in maize, and commercially worked an
industrial process for the production of glucose from maize.
Mering was the first to suggest that yeast contained a " ferment "
110 THE BREWER'S ANALYST
capable of converting maltose into glucose before alcoholic fer-
mentation, and Bourquelot shortly afterwards proved that maltose
is hydrolysed before fermentation is started, by acting upon
solutions of maltose with yeast in the presence of chloroform,
whereby the action of yeast cells is suspended.
More recent work, viz., that of Emil Fischer, has resulted in
substantiating Bourquelot's statement that yeast contains an
enzyme which hydrolyses maltose to glucose preliminary to
fermentation, the presence of the glucose being identified by his
now well-known osazone reaction with phenyl-hydrazine. Fischer's
investigations in these respects have since been repeated and
confirmed by Morris, who extracted the active enzyme from yeast
cells, quickly dried upon porous plates.
Besides the glucase of maize and yeast, the enzyme is widely
distributed in nature, and is frequently associated with the
diastatic enzymes. Bourquelot identified it in many plants and
nearly all moulds. It is not found, however, in the lactose or
kephir yeasts, S. marcianus or S. apiculatus.
In the majority of instances it is looked upon as a starvation
phenomenon, secreted by the living cell in proportion as it is
deprived of the presence of the simple hexose sugars, such as
glucose, which alone appear to be directly assimilable. Thus
many moulds which ordinarily contain glucase do not secrete
the enzyme at all if continuously supplied with saccharose or
glucose, but if their supply of these sugars is cut off and maltose
substituted, then the secretion of the enzyme, glucase, is at once
stimulated in the plant cell by its deprivation of suitable food.
Glucase is found associated with invertase and diastase in
Aspergillus oryzae, and it has been shown by Atkinson that the
final product of the action of this enzyme on gelatinised starch is
glucose and not maltose.
Glucases have been found in the saliva, secretions of the
intestines and the pancreas,, and in various organs of animals.
The methods adopted for extracting glucase are similar to those
employed in the extraction of diastase and invertase, the extrac-
tion being accomplished by suitable solvents and precipitation by
alcohol. In the case of yeast, which in the fresh state yields no
glucase to water, the yeast must first be dried quickly upon
porous plates at low temperature, and the resulting mass, after
pulverising, digested with water at 86 - 95 F. (30 - 35 C.), or
by extraction with 1 per cent, sodium hydrate, and subsequent
precipitation.
To study the action of the glucase of yeast upon maltose, fresh
PROTEIDS OR ALBUMINOIDS AND ENZYMES 111
yeast is suspended in a solution of maltose. If the fermentative
action of the yeast be inhibited by the addition of chloroform,
toluene, or thymol, in the course of a few hours the progress of the
hydrolysis of the maltose c"an be followed by the lowering of the
opticity of the solution and the increase of its cupric-reducing
power.
The glucase prepared from maize is of a light, friable character,
brownish in colour, dissolving in water with difficulty, and pre-
cipitated from its solutions by alcohol. Aqueous solutions of
glucase of different origin quickly lose their activity, and their
action is weakened by the presence of alcohol, chloroform, and
antiseptics. The enzyme acts most energetically upon maltose,
but most glucases are capable of acting upon dextrin and malto-
dextrins, and some are capable of hydrolysing starch. As a rule
the glucase of cereals hydrolyse maltose readily, but acts with
difficulty upon starch, whilst on the other hand the glucase of
moulds acts more vigorously upon starch than upon maltose.
The presence of a slight acidity is favourable to the action of the
glucases, but is entirely arrested when the acidity of the medium
is equal to or above ;2 per cent.
The optimum temperature and that at which the enzyme is
destroyed varies with its origin as follows :
Origin. Optimum Temperature. Destroyed at
OTjl f^ T? C*
Yeast . . . 120-2 49 131-0 55
Penicillium glaucum . 113'0 45 158*0 70
Eurotiopsis gayoni . 122'0 50 131'0 55
Aspergillus niger . 140'0 60 176*0 80
Maize . . . HO'O 60 158-0 70
CYTASE.
In their epoch-making paper, " Researches on the Germination
of some of the Graminese," Brown and Morris published an account
of the existence of an enzyme produced during the germination of
barley to which they gave the name cytase.
In order to thoroughly understand the action of this enzyme, it
is necessary to be first familiar with the structure of the barley-
corn and the morphological changes occurring during germination.
As before stated, under Diastase, plants possess three distinct
diastases, called respectively secretion diastase, translocation
diastase, and cytase. The first named is that present in germinat-
ing seeds ; the second is the diastase of ungerminated seeds and
112 THE BREWER'S ANALYST
other plant organs ; whilst cytase is an enzyme which possesses
the power of dissolving the cell walls.
The distinguishing feature between secretion and translocation
diastase is the inability of the latter to exercise any solvent action
on ungelatinised starch granules.
In the barleycorn the columnar cells (termed the epithelium,
forming the membrane intervening between the endosperm and
embryo) secrete the diastase necessary for the resolution of the
reserve material stored up in the endosperm, performing a duty
analogous to that of the alimentary canal and of the walls of the
stomach, which secrete the enzymes necessary for the proper
digestion and assimilation of food by animals.
During malting it was formerly considered that diastase was
the immediate cause of that mealiness and friability which
indicates the modification of rnalt ; or, in other words, that the
starch of the endosperm was gradually modified by the action
solely of secretion diastase. It is now shown, however, that
before this diastatic action can proceed, it is first necessary for the
cell walls to be dissolved, and the enzyme which performs this
dissolving action is cytase.
Cytase is the agent which attacks the cellulosic tissue of the
endosperm cells, breaking it down and causing its complete dis-
solution. 1 Following this there is an erosion of the starch
granules by secretion diastase, but this action on the starch
granules never takes place so long as the walls of the cells
containing them are intact.
The two enzymes diastase and cytase are quite distinct,
the action of cytase on the cell walls of the endosperm always
preceding that of the diastase on the starch granules. The pro-
duction of mealiness or friability in the content of the endosperm
is therefore, according to Brown and Morris, "coterminous with
the dissolution of the cell wall," and is entirely independent of the
disintegration of the starch granules.
In their endeavour to locate cytase in the barleycorn, Brown
and Morris state that the elaboration of the enzyme, as well as
the diastases, is carried out by the columnar cells forming the
epithelium dividing the scutellum of the embryo from the endo-
sperm ; and that its first action could be traced upon the depleted
cells adjacent to the embryo, and thence proceeding slowly
1 It appears to be an open question as to whether the cell walls are entirely
or only partially dissolved by cytase, but apart from this it is sufficient that
cytase opens the door sufficiently wide, so to speak, to render the starch of
the endosperm permeable to the action of secretion diastase.
PROTEIDS OR ALBUMINOIDS AND ENZYMES 113
throughout the corn. Tangl and Haberlandt were able to show,
however, that the secretion of cytase is not due to the epithelial
cells alone, but that a triple row of cells surrounding the endo-
sperm, termed aleurone ceUs, exercise a marked influence upon the
progress of the dissolution of the cell wall, and this view was
afterwards accepted by Brown and Escombe.
Sachs was the first to demonstrate the existence of a special
enzyme capable of attacking the less resisting forms of cellulose
during germination of the date seed, and later Green endeavoured
to isolate the enzyme. Brown and Morris were the first, however,
to isolate cytase from malt, and this they accomplished by making
infusions of air-dried malt, precipitating the enzyme with alcohol,
and carefully drying the precipitate in vacua. This preparation
was found to exhibit marked cyto-hydrolytic action (cellulose
dissolving power). Its action upon cellulosic tissue is, however,
more or less restricted to the cell walls of the endosperm of the
seeds from which the enzyme has been derived, or similar tissues
from seeds belonging to the same material order. Thus the
cytase derived from germinated barley acts readily upon the
cellular tissues of the endosperm of the Graminese, but is less
active towards similar tissues from other groups ; and it appears
to be a general rule that the cytases are most active upon the
cell walls of the particular seed in which the enzyme has been
elaborated.
Cytase is not capable of acting upon all forms of cellulose, this
term being used to embrace the members of a general group of
substances, forming the fabric of plant structures, similar in
chemical composition but differing in certain chemical and
physical characteristics. Thus the cellulose material forming
parenchymatous tissue, as found in the cellular membranes of the
barleycorn, is less resistant to chemical and enzyme action than
the lignified tissues of cellulose constituting the husk. As will
have already been seen under Cellulose, the former kind is termed
hemi-cellulose in order to distinguish it from the more stable and
resistant forms which are unacted upon.
The products of the action of cytase are generally understood to
be substances of a gummy nature, but have not yet been identified ;
whatever the nature of such products may be, it is generally
considered that they serve as food for the embyro during the
early stages of germination.
Giiss considers the hemi-cellulose of barley to be of the nature
of arabinoxylan, yielding, as the result of cyto-hydrolysis, the
pentoses arabinose and zylose, and similar substances have been
114 THE BREWER'S ANALYST
shown to exist in cold-water extract of malt, Morris indicating
that the unfermentable reducing residue of beer may in some
measure be attributed to the products of cytase hydrolysis during
germination.
Cytase is very sensitive to the action of heat. The activity of
a cold-water infusion of air-dried malt is greatly weakened in its
action, so far as cellulosic tissues are concerned, if heated to 122 F.
(50 C.), and this power is completely destroyed if heated for a
short time to 140 F. (60 C.), although the amylo-hydrolytic power
of diastase is still energetic in its liquefying and saccharifying
action upon starch granules beyond these temperatures. Owing
to this ready destruction of the enzyme, it will be understood that
only green malt, dried at a low temperature, contains active cytase,
ordinary malt being devoid of it owing to its complete destruction
during kiln-drying.
INVERTASE.
Invertase was discovered in 1830 by Doebereiner and Mitscher-
lich, who described it as a "soluble material" extractable from
yeast when the latter substance is mixed with water. The soluble
material liquefies cane-sugar and produces inversion in it by
causing it to take up the elements of water.
In 1860 Berthelot discovered that invertase could be pre-
cipitated, by means of alcohol, from its solution without losing its
activity, arid since this date numerous experimental data, showing
means by which the ferment can be extracted from yeast and its
properties when extracted, have been produced by Be'champ,
Donath, Seyler, Gunning, Tulkowsky, Konig, Kjeldahl, Mayer,
Earth, and Miiller. In all their experiments, however, no notice
was taken of the age of the yeast or its condition as regards health
or disease, and this seems the more strange considering that long
previously (1835) Schwann had shown Leuwenhoek's globular
yeast particles to be alive. All of any considerable importance
that was pointed out in this direction was that dead cells parted
with their invertase more freely than living cells, no mention
being made of the further fact that healthy yeast yields none of
its invertase or hydrolysing agent or enzyme to water in which it
is washed.
The widespread occurrence of cane-sugar or saccharose in nature
is well known, but the biases, to which group cane-sugar belongs,
are not directly fermentable or immediately available as plant
food, but require to be split up into the simple liexose sugars,
dextrose and levulose, before either fermentation or assimilation
PROTEIDS OR ALBUMINOIDS AND ENZYMES 115
by the living cell can take place. Hence it is that nature provides
the transforming enzyme, and that cane-sugar in nature is
accompanied by the existence of invertase in the saps and juices
of plant cells which depend for their nourishment upon the
assimilation of the sugar.
Invertase plays an important part among the higher plants in
as much as by its aid the cane-sugar carried by the sap is rendered
available for building up the cell fabric. It is found in all parts
of the Gramineae ; C. O'Sullivan demonstrated its presence in the
roots, stalks, and leaves of wheat and maize, and others have noted
its presence in the leaves of many plants belonging to different
natural orders. Its presence in green malt is undoubted, and
according to Brown and Morris, Kjeldahl and others, it is present
in kilned malt, not being wholly destroyed during kilning. In
animals, invertase has been located in some of the organs, its
presence in the intestinal secretions being first discovered by
Bernard.
Invertase is invariably present in yeast cells, usually associated
with other enzymes such as glucase and zymase. It is not, how-
ever, present in all yeasts, for Hansen has shown that Saccharo-
myces apiculatus, the yeast found on many fruits, is devoid of it.
Invertase has been found in many of the mould fungi, among
which the genus Aspergillus may be specially mentioned, the
invertase of Aspergillus niger, Aspergillus oryzx, or taka ferment
having been closely investigated. Invertase is also secreted by
Mucor racemosus, Penicillium glaucum, and Penicillium Duclauxii.
It also occurs in many species of Fusarium, and has been shown
to be present in Manila Candida. Its occurrence in this organism
is of special interest from the fact that, although it readily
transforms cane-sugar, an active enzyme cannot be prepared from
it by the usual methods, the investigations of Fischer and others
having demonstrated that, unlike the invertase of most organisms,
the invertase secreted by Manila Candida is insoluble.
Invertase has also been shown to be secreted by many bacteria,
among which B. mesentericus vulgatus, B. megatherium, and the
Cholera vibrio may be mentioned. It also occurs in Leuconostoc
mesenter bides, the "frog spawn" of beet-sugar juices. J.
O'Sullivan states :
" 1. Healthy yeast yields none of its invertase or hydrolytic
power to water in which it is washed.
"2. When healthy yeast is placed in contact with cane-sugar
solution, the hydrolysis that takes place is solely an action under
the immediate influence of the plasma of the cell, and no invertase
116 THE BREWER'S ANALYST
leaves the yeast cell during the time the hydrolysis is being
effected.
" 3. The hydrolytic action of yeast on cane-sugar takes place
without increase of yeast, and there is no alcohol formed. The
power which yeast possesses of producing alcoholic fermentation
is not altered in any way by the yeast having first hydrolysed
sugar-cane, and this is the case whether the hydrolytic action is
brought about in the first instance in the presence of air or
carbon-dioxide."
C. O'Sullivan and Tompson point out as follows :
" 1. When yeast is placed in cold water and allowed to remain
for a few hours, what is known as ' osmosis ' takes place, that is
to say, a soluble albuminous substance contained in the torpid and
dead cells, being extremely soluble in water, diffuses through the
cell membrane of the yeast and passes into the exterior liquid.
"2. If sound brewers' yeast be pressed and placed in a large
wide-mouthed vessel covered with a filter paper to prevent access
of dust, and allowed to stand at the ordinary temperature for a
month or two, or at a temperature of 64-4 -68'0 F. (18-20
C.) for 7-14 days, during this time auto-fermentation of the yeast
takes place, and the mass liquefies, yielding a thick yellow liquid
of not unpleasant smell. If this liquid is then filtered by the aid
of a filter pump, a clear yellow liquid is obtained, having a specific
gravity of 1075"-! 080. The filtrate has an inverting power
equal to 30 per cent, of the original yeast. It will remain for a
long time unaltered, excepting that the colour darkens ; and if
exposed to the air, it may slowly become covered with mould.
If spirit be added to the yeast liquid until the mixture contains
47 per cent, of alcohol, the whole of the invertase separates with
only a slight loss of power.
" This precipitated invertase may be washed with spirit of the
same strength, and then the residue either dehydrated with
strong alcohol and dried in vacuo, or else it may be extracted by
means of 10 to 20 per cent, alcohol and then filtered. The
filtrate contains the invertase. On one occasion it was deter-
mined what the loss involved by this process amounted to, and
it was found that 87 '7 per cent, of the invertase of the yeast
liquor was present in the filtrate."
C. O'Sullivan and Tompson have not, up the present,
succeeded in further purifying invertase preparations carefully
made in this manner, as the slightest attempt at purification
destroys the invertase. They have, however, succeeded in
preparing the enzyme almost free from ash.
PROTEIDS OR ALBUMINOIDS AND ENZYMES 117
Invertase prepared by the foregoing process is a fairly white
powder, which soon becomes yellowish on exposure to air and
light. It is soluble in water, giving clear solutions which are
not coagulated on heating. Solutions of invertase are dextro-
rotatory, and, according to 0. O'Sullivan, the specific rotatory
power of pure invertase is [a\- } = + 80. Invertase is readily
precipitated from its solutions by the addition of alcohol, and is
completely insoluble in alcohol of specific gravity '940. The
precipitates are of a semi-syrupy nature, and usually contain
inorganic salts precipitated from the solutions by alcohol,
although a considerable quantity of these inorganic bodies can be
eliminated by washing the precipitate with alcohol.
Invertase can be separated from solutions by filtration through
porcelain or by parchment in a dialysing apparatus. It is
difficult to keep it either in solution or as a dry preparation
without loss of power, this being probably due to oxidation in
the presence of light. It is extremely sensitive to temperature
above the normal or optimum when in solution, but when
perfectly desiccated will withstand the temperature of the boiling-
point without appreciable loss of power.
Little is known of the constitution of invertase j most
authorities concur that it is not an albuminoid. It gives no
coloration with Millon's reagent in the cold, but on heating, a
pink coloration is produced. It does not reduce Fehling's
solution.
O'Sullivan considers invertase, as separated from yeast, to be
a mixture of yeast albuminoid and a carbohydrate. As the
invertase approaches the pure state it becomes a very unstable
body, the purification resulting in the formation of decomposition
products designated the Invertan series, which may be expressed
in terms of a carbohydrate of the formula :
Carbon, 43*22, hydrogen, 6 28, oxygen, 50'40, and an
albuminoid (yeast albuminoid)
Carbon, 54'33, hydrogen, 7 '50, nitrogen, 14 '88.
Seven members of the Invertan series were examined and their
properties described. According to O'Sullivan the proportion of
carbohydrate to yeast albuminoid varies from '74 part in a
Invertan, the first member of the series, to I2'84 parts in n
Invertan. All the members of the group are devoid of inverting
power with the exception of the second member of the l> Invertan,
this constituting the true enzyme invertase.
The action of invertase upon cane-sugar is one of simple
hydrolysis, and the change, which is precisely the same as that
118 THE BREWER'S ANALYST
effected by acids, consists in the assimilation of water by the
cane-sugar molecule, followed by its separation into the two
different kinds of sugar dextrose and levulose which though of
very different properties have the same formula :
C 12 H 22 O n + OH 2 = C 6 H 12 6 + C f) H 12 6 .
Cane-sugar. Water. Dextrose. Levulose.
Invert-sugar.
Like most enzymes, the action of invertase is influenced by
concentration, temperature, and the nature of the medium; the
amount of inversion being governed by the quantity of invertase
present and the time its action is allowed to continue.
The most favourable concentration for sugar solutions is
between 20 and 30 per cent, of sugar, a decline in the speed of
inversion taking place when the solutions are dilute or in
saturated solutions above 40 per cent. The rapidity of inversion
is greatly influenced by the temperature. At low temperatures
the inversion proceeds slowly, rapidly increasing with every
increment of temperature until the optimum of 131-140 F.
(55-60 C.) is reached. The optimum temperature is not a
constant one, but varies according to the source from which the
invertase is derived. The invertase of top fermentation yeast
acts best at a temperature of 131-140 F. (55-60 C.), whilst
the invertase from bottom fermentation yeast exhibits its
maximum effect between 86-95 F. (30-35 C.). At tempera-
tures above 140 F. (60 C.) the activity declines, and the
enzyme is weakened by exposure to the elevated temperature
until at 167 F. (75 C.) it is totally destroyed.
The activity of invertase is at a maximum when acid is present
iu normal amount, this, according to O'Sullivan being, for tempera-
tures of 131-150 F. (55-65-5 C.), 1'25 parts SO 3 per 100,000
(=0016 percent. H 2 S0 4 ).
It is, however, extremely sensitive to any increase of acidity.
The presence of alkali is absolutely destructive to its action, and
the presence of alcohol is distinctly prejudicial, the decrease of
activity being proportional to the amount -of alcohol present.
The action of invertase upon cane-sugar is rapid in regard to
speed and enormous as to amount. O'Sullivan illustrates these
points by two striking experiments :
A preparation of invertase reduced the optical activity of a
solution of cane-sugar to the zero point [a] D = in 25'1 minutes,
the sugar being present in the proportion of 100 to 1 of invertase
added. This is equivalent to the inversion of 74 times its own
PROTEIDS OR ALBUMINOIDS AND ENZYMES 119
weight of cane-sugar in 25*1 minutes. By adding a weighed
quantity of invertase to a large bulk of cane-sugar, and digesting
at a temperature of 122-1 29-2 F. (50-54 C.) for a fortnight,
it was found that an inversion equal to 100,000 times its weight
of invertase added had taken place, and that the inverting action
was still slowly progressing.
ZYMASE.
In 1 897 the scientific world was startled by the discovery by
Dr E. Buchner of an enzyme extractable from yeast capable of
fermenting solutions of cane-sugar. The idea was at first looked
upon as incredible, owing to the long-cherished famous dictum of
Louis Pasteur, viz., that " Fermentation is the physiological effect
of the life-action of yeast and other cells." Buchner, however,
very quickly proved his point, having succeeded in extracting from
yeast an active liquid capable of effecting the decomposition of
sugar without the direct agency of living cells, and established
beyond question that the production of alcohol by yeast fermenta-
tion does not differ essentially from other zymolytic decomposi-
tions, but is analogous to the inversion of cane-sugar by invertase,
and the hydrolysis of maltose by yeast glucase. Buchner obtained
the active alcoholic enzyme as follows :
Fresh yeast is first subjected to a pressure of 750 Ibs. to the
square inch, in order to free it from adherent liquid. It is then
mixed with an equal weight of quartz-sand and a fifth of its
weight of kieselghur 1 , and placed in a grinding mill driven by a
motor, and ground until the mass, at first pulverulent, becomes
moist and adheres together in balls. The object of this grinding
is to rupture the walls of the yeast cells, and to permit their
protoplasmic contents to escape. The doughy mass is then
enveloped in a cloth and placed in a hydraulic press, where it is
slowly and gradually submitted to pressure until at last a pressure
of between 3 and 3J tons to the square inch is reached. After
about two hours the cake is removed from the press, broken up,
and moistened with water. It is then pressed as before. In this
way a mass of yeast yields about half its weight of yeast extract,
rather less than three-tenths of this extract consisting of the
water added to moisten the yeast cake. The yeast extract, as it
drops from the press, is allowed to pass through a funnel,
provided with a filter paper, into a vessel which is kept in ice, in
order to prevent decomposition of the extract as much as possible
1 A fine, earthy powder which consists of the siliceous coverings of diatoms.
120 THE BREWER'S ANALYST
during its preparation. A microscopic examination of the yeast
cake after the second pressing shows that only about 4 per cent,
of yeast cells remain intact. The extract obtained in this way is
a clear or slightly opalescent liquid, with a pleasant yeasty odour,
its specific gravity being about 1041 '6. On boiling, a considerable
amount of coagulum forms, so much so that the liquid is converted
into an almost solid mass. But the most remarkable property it
possesses is the power of inducing fermentation.
When equal volumes of the extract of a concentrated solution
of sugar-cane are mixed, or if powdered sugar-cane is dissolved in
the extract, in from 15 minutes to an hour a regular evolution of
carbon-dioxide commences, and this continues for several days.
Saturation of the mixture with chloroform does not arrest the
action, though it is a well-known fact that this substance com-
pletely stops fermentation when conducted with ordinary living
yeast. The fermentative power of the extract is not destroyed
when the extract is passed through a Berkefeld filter, and this
treatment would certainly remove from it all living organisms.
The yeast extract gradually loses its fermentative power when
kept at the temperature of an ice chamber, much more rapidly at
higher temperatures. It has been pretty conclusively shown
that this is due to the destruction of the zymase by another
enzyme of a proteolytic nature present in the extract. Living
yeast is unable to ferment solutions of cane-sugar of 50 to 60 per
cent, strength, or solutions to which large quantities of glycerine
have been added ; zymase ferments these readily. Like most"
other enzymes, zymase can be precipitated by alcohol, but on
subsequent solution in water it is found to have lost very much
of its activity. It may be obtained, however, in the dry state,
with little or no loss of activity, in the following manner :
500 c.c. of fresh yeast extract are evaporated, in a vacuum
apparatus, at a temperature of 68-77 F. (20-25 C.) until
of a syrupy consistency ; the syrup is then spread in thin layers
on glass plates and dried at a temperature of 93-95 F. (34-
35 C.) either in a vacuum or in the air, since it is found that,
when the above-mentioned degree of concentration has been arrived
at, air has no longer any effect upon the zymase. The dried
extract is then scraped off the plates, reduced to a powder, and
brought to a state of absolute dryness by being placed in a
desiccator over sulphuric acid. The 500 c.c. of yeast extract is
found to yield about 70 grams of this yeast powder, which has a
pleasant yeasty odour, and in appearance somewhat resembles
dried white of egg. If the 70 grams of yeast powder so obtained
PROTEIDS OR ALBUMINOIDS AND ENZYMES 121
are dissolved in 500 c.c. of water, that is, made up to the same
strength as the original yeast extract from which it was prepared,
a solution is obtained which possesses nearly the same fermenta-
tive power as the original yeast extract.
In the dried form the fermentative power of the enzyme can
be preserved for a longer period than in the liquid state, some
preparations retaining their activity for 20 days, whilst those
concentrated in vacuo preserved their full activity for over two
months.
Buchner further demonstrates that the yeast cell can be so
dried as to destroy its vitality without impairing the activity of
the zymase, which can still exert its fermentative function in situ
within the cell membrane. The yeast is first well washed with
water, and after removing extraneous moisture as much as
possible by pressure, it can be perfectly dried in two or three .
days if spread out in thin layers, A yellow powder is obtained *";
which, on heating to 212 F. (100 C.) for 5 to 6 hours, becomes
completely sterile, the vitality of the cells being wholly destroyed
and no longer capable of developing in nutrient solutions. That
the zymase is not destroyed by this procedure is evidenced by the
fact that, when the powder is placed in a saccharine solution,
fermentation is set up.
Yeast extract, representing the sap or juice of the cell, contains,
besides zymase, those other enzymes known to be secreted by the
living cell, viz., invertase and glucase, in addition to which a
proteolytic enzyme and an oxydase have been noted. The
presence of an amylase, however, does not appear to have been
definitely established. Hence the zymase is capable of fermenting
those sugars which are ordinarily decomposed by the living cell,
whether directly as dextrose and levulose, or fermentable only
after hydrolysis, such as saccharose, maltose, etc., which require
the presence of specific enzymes. It has been found that maltose,
saccharose, dextrose, and levulose are equally rapidly fermented
by zymase. In the case of the two last-named sugars, how-
ever, this is not the case when fermented by the living cell, the
greater diffusibility of dextrose through the cell membrane
causing the fermentation of this sugar to proceed more quickly
than that of levulose ; in fact a solution of invert-sugar under-
going fermentation increases in Isevo-rotatory power. With
the expressed yeast extract (zymase) this phenomenon does
not occur, both dextrose and levulose being decomposed uniformly.
Of other carbohydrates, raffinose, galactose, and glycogen are very
slowly attacked, whilst lactose and arabinose are not fermented
122 THE BREWER'S ANALYST
by it ; in fact only those carbohydrates which are readily hydro-
lysed by the enzymes of ordinary yeast with the formation of
simple hexose sugars are capable of fermentation by yeast.
Buchner, studying the specific action of zymase, found that
the relative proportion of C0 2 to alcohol produced by the enzyme
during fermentation, does not wholly agree with the ratio obtain-
able by living-cell fermentation, the amount of alcohol being
usually in excess. In one experiment the quantities found were
C0 2 = 6'7 grams, alcohol 7'72 grams, an excess of '72 grams
alcohol.
Macfadyen and Morris also showed that the amounts of alcohol
and carbon-dioxide produced were less than should be yielded by
the amount of saccharose which disappears, so that it is evident
that the decomposition of sugar by zymase, like the action of the
living cell, cannot be a simple decomposition such as can be ex-
pressed by the equation of Gay-Lussac
It is more than probable, therefore, that complex combinations
between the enzyme and the carbohydrate, followed by decom-
position, take place before the final products, alcohol and carbon-
dioxide, result. In cell fermentation, too, secondary products,
glycerol and succinic acid, are formed ; and the investigations
of Buchner show that these products are also formed by the
action of zymase, although in much smaller amount.
The fermentative power of zymase was found by Lange to
increase with the ratio of nitrogen, this fact being in accordance
with the conclusions of Hayduck, who showed this to be the case
with living yeast. Zymase appears to closely resemble albumin,
but it differs in many respects from invertase. It is in some of
its properties analogous to the enzyme of Manila candida, par-
ticularly in the extreme difficulty with which it diffuses, if at
all, through cell membranes or parchment. Although the
action of zymase is not impeded by the presence of antiseptics
which are inimical to yeast growth, thus behaving as a true
enzyme, it is extremely sensitive to the presence of excessive
amounts of inorganic substances. Neutral salts in small quantity
appear to favour the action, but if they are increased beyond 1 '5
per cent., the action is completely arrested. Acids and alkalies
are both unfavourable, but in minute quantities appear to
stimulate it. Phosphates, particularly acid phosphates, in small
proportion, exercise a stimulating effect. Fermentation is
diminished by the addition of 15 per cent, alcohol, whilst the
PROTEIDS OR ALBUMINOIDS AND ENZYMES 123
presence of 20 per cent, completely arrests it, the enzyme being
practically precipitated.
Here then we have the most conclusive evidence that Buchner's
yeast extract contains an ertzyme which is the cause of alcoholic
fermentation, and as with other enzymes it has not been found
possible to obtain zymase in a state of purity, no attempt has
been made to ascertain its true chemical composition.
PART IV.
INDICATORS USED IN ALKALIMETRY.
LITMUS SOLUTION AND PAPERS.
1. Litmus Solution. It is customary, in testing both acids
and alkalies, to employ a solution or papers of litmus. The
solution may be prepared as follows :
Weigh about 10 grams of solid litmus, reduce to powder, and
boil with alcohol of about 80 per cent. Let stand for some time,
then pour off the alcohol, it being no longer required for the
preparation. Colouring matter, which is a hindrance to the proper
reaction, is thus removed. Now digest the litmus repeatedly with
cold distilled water till all soluble colour is extracted, let the
mixed washings settle clear, decant, and add to them a few drops
of concentrated sulphuric acid until quite red, then heat to
boiling ; this will decompose the alkaline carbonates and convert
them into sulphates. Now cautiously add baryta water until the
colour is restored to blue or violet, let the baric sulphate settle
perfectly, and decant into a bottle for use. Litmus solution so
prepared is very sensitive to dilute acids and alkalies ; with the
slightest excess of oxalic, sulphuric, hydrochloric, or nitric acids it
gives a pink-red, and with caustic soda or potash, a blue colour;
with ammonia or the bicarbonated alkalies it retains its violet
colour, and the same with most of the neutral salts of the weak
acids, such as sodium or ammonium acetate or borax. Free
carbonic acid interferes considerably with the production of the
blue colour, and its interference in titrating acid solutions with
alkaline carbonates can only be got rid of by boiling the liquid
during the operation, in order to displace the gas from the
ammonia. If this is not done, it is easy to overstep the exact
point of neutrality in endeavouring to produce the blue colour.
124
INDICATORS USED IN ALKALIMETRY 125
The same difficulty is also found in obtaining the pink red when
acids are used for titrating alkaline carbonates, hence the great
value of the caustic alkaline solutions free from carbonic acid in
acidimetry.
Litmus papers are simply made by dipping strips of unglazed
paper in the solution and drying them ; if required red, the liquid
is slightly acidified.
Neither the solution nor papers should be used by gaslight, nor,
as stated, for testing any solution containing free C0 2 .
2. Methyl-orange (a salt of sulpho-benzene-azo-dimethyl-
amine).
Solution. One gram in a litre of distilled water.
Used for titrating mineral acids in the cold : very useful for
ammonia and its salts. Inapplicable for hot liquids and organic
acids.
Special Properties. Its indifference to C0 2 and SH 2 in the
cold.
Colour Reaction. Pink, with excess of acids. Faint yellow, with
excess of alkali.
3. Phenol-phthalein (C 20 H H 4 ).
Solution. One gram in a litre of 50 per cent, alcohol.
Used for determining caustic fixed alkalies in presence of the
carbonates. Gives no colour with the bicarbonates. Absolutely
useless for the titration of free ammonia and its compounds, or
for the fixed alkalies when salts of ammonia are present.
Special Properties. Unlike methyl-orange, this indicator is
specially useful in titrating all varieties of organic acids oxalic,
acetic, citric, tartaric, etc.
Colour Reaction. Purple-red in alkaline solutions, rendered
colourless by excess of acid.
4. Cochineal Solution.
Solution. Digest one part of powdered cochineal with ten parts
of 25 per cent, alcohol.
This indicator is not very much modified in colour by C0 2 , and
can be used by gaslight. Most useful in titrating solutions of
the alkalies and alkaline earths. Inapplicable in presence of Fe
or Al compounds or acetates.
Colour Reaction. Yellowish-red turned violet by alkalies :
mineral acids restore the original colour.
5. Phenacetolin.
Solution. Two grams in a litre of alcohol.
Special Uses. To estimate KHO or NaHO in the presence of
K 2 C0 3 or Na 2 C0 3 , or CaO in the presence of CaC0 3 .
126 THE BKEWER'S ANALYST
Colour Reaction.
With NH 3 and normal alkaline carbonates dark pink.
,, bicarbonates intense pink.
mineral acids golden-yellow.
6. Rosolic Acid (C 20 H 16 3 ).
Solution. Two grams in a litre of 50 per cent, alcohol. This
indicator is excellent for use with all the mineral acids, but
unreliable for the organic acids.
Colour Reaction. Pale yellow, unaffected by acids, turned
violet-red by alkalies.
7. Iodine Solution. One gram iodine and 1 gram potassic
iodide in a litre of distilled water; or 1 per cent, solution of
decinormal iodine.
Used for detecting starch in mashes, worts, etc., in the cold ;
inapplicable for hot liquids.
Colour Reaction. Blue or violet with starch, reddish-brown with
erythro dextrins.
8. Ferrous Thiocyanate Solution. One gram of ferrous
ammonium sulphate and the same quantity of ammonium thio-
cyanate are dissolved in 10 c.c. of distilled water at a temperature
of about 120 F. (49 C.) and immediately cooled ; 5 c.c. con-
centrated hydrochloric acid are then added. The solution so
obtained has invariably a brownish -red colour, due to the presence
of ferric salt, which latter must be reduced. For this purpose
zinc dust is the most satisfactory reagent to employ, and a mere
trace is sufficient to decolorise the solution if pure reagents have
been employed.
When kept for some hours, the indicator develops the red
coloration by atmospheric oxidation.' It may, however, be
decolorised by the addition of a further quantity of zinc dust,
but its delicacy is decreased after it has been decolorised several
times. For practical purposes the indicator may be too delicate,
and it is therefore best to prepare it the day before it is required
for use, as it gives the best results after the second decolorisation.
The indicator is employed for ascertaining the reduction of the
copper in Fehling's test.
PART V.
PREPARATION OF STANDARD AND OTHER
SOLUTIONS.
STANDARD SOLUTIONS.
WHEN analysis by measure first came into use, the test solutions
were generally prepared so that each substance to be tested had
its own special reagent, and the strength of the standard solution
was so calculated as to give the result in percentages. Con-
sequently, in alkalimetry a distinct standard acid was used for
soda, another for potash, a third for ammonia, and so on, necessi-
tating a great variety of standard solutions.
Griffin and Ure were the first, however, to suggest the use of
standard test solutions based on the atomic system, and, following
in their steps, Mohr l worked out and verified many methods of
analysis, which are of great value to all who concern themselves
with scientific and especially technical chemistry.
Normal solutions as a general rule are prepared so that 1
litre at 60 F. (15'5 C.) shall contain the hydrogen equivalent
of the active reagent weighed in grams (H = l). Decinormal
solutions are made one-tenth, and centinormal one-hundredth of
N N
this strength, and may be shortly designated as and -
10 100
solutions.
In the case of univalent substances such as silver, iodine,
hydrochloric acid, sodium, etc., the equivalent and the atomic
(or, in the case of salts, molecular) weights are identical ' f thus a
normal solution of hydrochloric acid must contain 36-5 grams
of the acid in a litre of fluid, and sodic hydrate 40 grams.
Jn the case of bivalent substances such as lead, calcium, oxalic
acid, sulphurous acid, carbonates, etc., the equivalent is one-half
1 Lehrbuch der Chemisch Analytischen Titrirmethode.
128 THE BREWER'S ANALYST
of the atomic (or, in the case of salts, molecular) weight ; thus a
normal solution of oxalic acid would be made by dissolving 63
grams of the crystallised acid in distilled water, and diluting the
liquid to the measure of 1 litre.
Further, in the case of trivalent substances such as phosphoric
acid, a normal solution of sodic phosphate would be made by
358
weighing -g-,119'3 grams of the salt, dissolving in distilled
water, and diluting to the measure of 1 litre.
One important point, however, must not be lost sight of,
namely, that in preparing solutions for volumetric analysis the
value of a reagent as expressed by its equivalent hydrogen-weight
must not always be regarded, but rather its particular reaction in
any given analysis; for instance, with a solution of potassic
permanganate MnK0 4 , when used as an oxidising agent, it is the
available oxygen which has to be taken into account, and hence
in constructing a normal solution one-fifth of its molecular weight,
- = 31 '6 grams, must be contained in the litre.
Illustrations may be given in order to show the method of
calculating the results of this kind of analysis :
1. Suppose, for instance, that it is desired to know the quantity
of pure silver contained in a shilling. The coin is first dissolved
in nitric acid, by which means a bluish solution, containing silver,
copper, and probably other metals, is obtained. It is a known
fact that chlorine combines with silver in the presence of other
metals to form chloride of silver, which is insoluble in nitric acid.
The proportions in which the combination takes place are 35'5
of chlorine to every 108 of silver; consequently, if a standard
solution of pure chloride of sodium is prepared by dissolving in
distilled water such a weight of the salt as will be equivalent to
35*5 grams of chlorine ( = 58'5 grams NaCl) and diluting to the
measure of 1 litre (1000 c.c.), such a solution will be a normal
one, and every single gram measure of this solution will combine
with 0*108 gram of pure silver to form chloride of silver, which
is precipitated to the bottom of the vessel in which the mixture
is made. In the process of adding the salt solution to the silver
drop by drop (titrating), a point is at last reached when the
precipitate ceases to form. Here the process is stopped.
On looking carefully at the graduated burette from which the
standard solution has been used, the operator sees at once the
number of c.c.'s which have been necessary to produce the com-
plete decomposition. For example, suppose the reading, that is
PREPAKATION OF STANDARD AND OTHER SOLUTIONS 129
to say, the number of c.c.'s used, equalled 33 7, all that is
necessary to be done is to multiply 33*7 by the coefficient for
each c.c., viz., 0*108, which shows the amount of pure silver
present to be 3*63 grams.-
Inversely, it is obvious that one may similarly test a substance
for the quantity of chlorine by titrating a dissolved and measured
quantity with a standard solution of silver.
N
2. Each c.c. of silver solution will contain T o\J-<nr of the
atomic weight of silver = 0*0108 gram, and will exactly precipitate
"nr.FinF f tne atomic weight of chlorine = 0*00355 gram from any
solution of a chloride.
3. In the case of normal oxalic acid each c.c. will contain ^^
of the molecular weight of the acid = 0*063 gram, and will
neutralise ^-^^ of the molecular weight of sodic carbonate =
0'053 gram, or will combine with -g-irW f ^ ne atomic weight of
a dyad metal such as lead = 0'1 035 gram, or will exactly saturate
TWO u" ol? * ne molecular weight of sodic hydrate = 0*040 gram, and
so on.
The great convenience of this equivalent system is, that the
numbers used as coefficients for calculation in any analysis are
familiar, and the solutions agree with each other, volume for
volume.
We have hitherto looked only at one side of its advantages.
For technical purposes, the plan allows the use of all solutions of
systematic strength, and simply varies the amount of substance
tested according to its equivalent weight.
Thus the normal solutions, say, are
Sulphuric acid . . . .49 grams per litre
Nitric acid .... 63 ,, ,,
Oxalic acid . . 63 ,, ,,
Hydrochloric acid . . . 36*5 ,, ,,
Sodic hydrate .... 40 ,, ,,
Sodic carbonate .... 53 ,,
100 c.c. of any one of the normal acids should exactly neutralise
100 c.c. of any of the normal alkalies, or the corresponding
amount of pure substance which the 100 c.c. contain.
It is obvious that no experiment, however carefully performed,
can be accurate unless the chemical reagents are pure and of
the proper strength. It is also obvious that even if these con-
ditions apply, proper quantities cannot be weighed without the
balance is in perfect order, and that all burettes, pipettes, and
9
130 THE BREWER'S ANALYST
measuring flasks are perfectly graduated. It is therefore highly
essential that these conditions should be carefully looked to, and
particularly that burettes, pipettes, and measuring flasks be
standardised, and re-marked with a file if practicable, or other-
wise rejected and perfect ones obtained.
In the making up of all standard solutions a further essential
is that the distilled water in use be perfectly pure and in most
instances particularly free from ammonia.
We may now proceed to a consideration of the
PREPARATION OF STANDARD AND OTHER SOLUTIONS.
To begin with, volumetric solutions may be divided into two
groups :
(a) Permanent solutions, e.g., of sodium chloride, hydrochloric
acid, and oxalic acid, which may be accurately prepared, and will
keep well if properly stored. These may be regarded as true
standards with which other solutions may be compared. If there
be a doubt as to the exact strength of the standard, it is better,
as a rule, to check it against a known weight of a suitable re-
agent rather than by some other standard solution.
(b) Non-permanent solutions, such as ferrous salts and dilute
thiosulphate. With such it is a waste of time to aim at getting
some definite strength. An approximation will suffice, the exact
litre being determined each time of use by trial against some
permanent standard, or a known weight of some reagent.
NORMAL SULPHURIC ACID
= 49 grams H 2 S0 4 per litre
1 c.c. = 0-049 gram H 2 S0 4
0-048 S0 4
0-040 S0 3
0-090 albumin
O'OIT ,, ammonia
0*014 ., nitrogen.
Run about 30 c.c. pure sulphuric acid, specific gravity 1-84, into
a litre flask about a quarter full of distilled water ; cool and make
to mark at 60 F. (15*5 C.) with distilled water.
If the acid from which the solution has been made was of the
specific gravity mentioned, the solution will be too strong, which
is preferable, on account of the ease by which, in preference to a
weak solution, it can be rendered accurate.
PREPARATION OF STANDARD AND OTHER SOLUTIONS 131
To test its strength several methods may be employed, the
best being perhaps as follows :
Weigh 2 grams of pure anhydrous sodic carbonate recently
heated and cooled under "a desiccator and place in a tared
platinum dish. Dissolve in a small quantity of distilled water,
covering the dish with a watch glass. Temporarily remove the
watch glass and run in exactly 25 c.c. of the sulphuric acid to
be standardised and immediately replace the watch glass. When
the effervescence at first occurring has ceased, place the dish on
the water bath and evaporate the contents to complete dryness,
previously rinsing in any drops of liquid which may have collected
on the inner surface of the watch glass. Now heat to 350 F.
(176 '6 C.) in an air bath, cool under desiccator, and weigh, re
peating this until the weight is constant.
From this the exact strength of the made solution may easily
be calculated.
The CO 2 in the sodic carbonate has been displaced by S0 3 ,
and, as the atomic weight of the former is 44 as against 80 for
the latter, it is evident that the increased weight of the residue
over that of the sodic carbonate originally taken is proportional
to the amount of sulphuric acid employed, provided an excess
of the salt named be present and the quantity recommended
ensures this being so.
Example :
Platinum dish and Na 2 C0 3 = 68*904 grams.
Platinum dish = 66*808
2-096
25 c.c. of the sulphuric acid of approximately normal strength
were run in, and the whole evaporated to dryness, heated to
350 F. (176'6C.) for some time, cooled under a desiccator arid
weighed. The dish and contents now weighed 69*382 grams,
an increase of 0'478 grams. This increased weight is in pro-
portion to the difference between the atomic weights of C0 2
and S0 3 , that is, 44C0 2 will be replaced by 80S0 3 , or the presence
of 80 parts S0 3 will give an increased weight of 36. Therefore
36 : 80 : : 0'478 : 1'062 grams of S0 3 in 25 c.c. of dilute acid, or
4 '248 grams per 100 c.c. in place of 4*00, the correct quantity.
We therefore now dilute this as follows :
4-00 : 100 : : 4-248 : 1-062.
That is, each 100 c.c. must be diluted to 106-2 to make it of
correct strength.
132 THE BREWER'S ANALYST
The accuracy of this may be verified by making another ex-
periment with the dilute liquid, either by evaporation with sodic
carbonate as before, or as follows :
Run 10 c.c. normal alkali into a small beaker or flask, add a
few drops of litmus or methyl-orange, and allow the acid to flow
from a 10 c.c. pipette, divided into -^ c.c., until the point of
neutrality is reached. If more than 10 c.c. are required, the acid
is too weak ; if less, too strong.
Suppose it required 8*9 c.c. to saturate the 10 c.c. of alkali.
890 c.c. will be required to make 1 litre of standard acid ;
remove, therefore, the excess from the litre flask and dilute to
mark. Now test again with the pipette, and if the previous
examination was correct, 10 c.c. of each solution should exactly
neutralise each other.
As a further check upon the accurate strength of the solution,
it is advisable to use larger quantities, say 50 or 100 c.c., for the
final adjustment. The solution may also be controlled by pre-
cipitation with baric chloride, in which case 10 c.c. should
produce as much baric sulphate as is equal to 0*49 gram of
sulphuric acid, or 49 grams per litre.
NORMAL NITRIC ACID
= 63 grams HN0 3 per litre
1 c.c. = 0-063 gram HN0 3
0-062 N0 3
0-054 N 2 5 .
Nitric acid used for making the normal solution should be
colourless, free from chlorine and nitrous acid, and of a specific
gravity of from 1*35 to 1'40. If the acid is coloured from the
presence of nitrous acid, it should be mixed with an equal volume
of distilled water and boiled until colourless. When cold it may
be diluted and titrated against pure sodic carbonate, as described,
with normal sulphuric acid.
/N
NORMAL OXALIC ACID (
= 63 grams H 2 C 2 4 , 20H 2 per litre
1 c.c. = 0-063 gram H 2 C 2 4 , 20H 2
0-045 H 2 C 2 4 .
This solution possesses the advantage that it may be established
directly, by weighing 63 grams of the pure crystallised acid,
PREPARATION OF STANDARD AND OTHER SOLUTIONS 133
dissolving the same in distilled water and making to the bulk
of 1 litre at 60 F. (15'5 C.). The acid should be recrystallised,
thoroughly air-dried, but not in the slightest degree effloresced.
The solution keeps well, and will bear heating without volatilising
the acid. The solution should be titrated against a normal
solution of sodic carbonate.
/N
NORMAL HYDROCHLORIC ACID f
= 36"5 grams HCL per litre
1 c.c. = 0-0365 gram HCL
0-0355 Cl.
About 181 grams of pure hydrochlorlic acid (sp. gr. 1*10) made
up to 1 litre at 60 F. (15-5 C.) with distilled water. The solution
should be titrated against normal alkali.
NORMAL ALKALI.
Normal alkali may consist of either soda, potash, or (less
recommendable) ammonia.
As pure sodic hydrate, manufactured from metallic sodium and
free from carbonic acid, is readily obtainable, the standard solution
is made from it as follows :
CN\
- )
= 40 grams NaHO per litre
1 c.c. = 0-040 gram NaHO
0-031 ., Na 2
0-06 ,, acetic acid
0-09 lactic acid.
Dissolve about 42 grams sodic hydrate in about 800 c.c.
distilled water, cool to 60 F. (15 '5 C.). Titrate a portion of this
solution with normal acid, calculate therefrom its exact strength
and the dilution necessary to reduce it to 40 grams of actual
NaHO per litre.
NORMAL SODIC CARBONATE (
= 53 grams Na 2 C0 3 per litre
1 c.c. =0-053 gram Na 2 C0 3
0-030 C0 3
0-022 C0 2 .
134 THE BREWER'S ANALYST
Dissolve 53 grams of pure and dry sodic carbonate in distilled
water and dilute to 1 litre at 60 F. (15'5 C.). The solution should
be titrated against normal hydrochloric acid.
DECINORMAL ACID OR ALKALI (
Run 100 c.c. normal acid or normal alkali into a litre flask
about quarter full of distilled water, cool, and make to mark at
60 F. (15'5 C.) with distilled water.
FOUR-TIMES NORMAL ACID OR ALKALI
Take 400 c.c. of strong hydrochloric acid and make up at 60 F.
(15-5 C.) with distilled water to 1 litre. The solution may be
titrated against normal alkali and appropriately diluted; each
c.c. of the corrected standard should require 4 c.c. of normal
alkali.
The corresponding four-times normal alkali is made by dissolving
about 170 grams of sodic hydrate in distilled water, cooling, and
making up to 1 litre. The solution may be titrated against four-
times normal acid.
The acid solution is generally employed for inverting cane-
sugar, and the corresponding alkali for neutralising the acidity
after inversion. The solutions, however, need not be of exact
strength.
DECINORMAL POTASSIC PERMANGANATE
/NX
VioJ
= 3*156 grams MnK0 4 per litre
1 c.c. = 0-0056 Fe
0-0072 FeO
0-0080 Fe 2 3
0-0017 H 2 S
0-0056 CaO.
Weigh 3*156 grams pure crystal potassic permanganate and
dissolve with a little distilled water (free from ammonia) in a litre
flask and make to mark at 60 F. (15 '5 C.). In standardising the
solution it should react with its own volume of oxalic acid.
The solution should be kept in a well-stoppered bottle, and
while it is quite free from sediment, it may be taken for granted
PREPARATION OF STANDARD AND OTHER SOLUTIONS 135
that its strength is unaltered. It will retain its strength for
several months.
DECINORMAL IODINE
'H\
aoy
= 12 '7 grams I per litre
1 c.c. = 0-0032 gram S0 2 .
Chemically pure iodine may be obtained by mixing commercial
iodine with about one-fourth of its weight of potassic iodide and
gently heating the mixture between two large watch glasses or
porcelain capsules, the lower one being placed upon a heated iron
plate, when the iodine sublimes in brilliant crystals which are
absolutely pure.
The resublimed iodine of commerce is not always free from
chlorine, and, unless purchased absolutely pure, it becomes
necessary to prepare it by a second sublimation as described.
The watch glass or capsule containing the iodine is then placed
under the desiccator so that the iodine may be cooled and freed
from traces of moisture; then 12'7 grams are weighed and,
together with about 18 grams of pure white potassic iodide,
dissolved in about 250 c.c. distilled water.
The solution is then transferred to a litre flask, and made to
mark at 60 F. (15'5 C.) with distilled water. The flask should not
be heated in order to promote solution, and care should be taken
that iodine vapours are not lost during the operation. The solution
N
should be titrated against potassic permanganate :
Take 10 c.c. of the permanganate, dilute with distilled water,
acidify with sulphuric acid. Add potassic iodide, and titrate with
N N
sodic thiosulphate. Then titrate 10 c.c. of the iodine with
the same thiosulphate solution. The volume consumed should
be the same as in the previous titration.
(N
= 24'8 grams Na 2 S 2 3 , 50H 2 per litre
1 c.c. = 0-01 265 gram I.
As it is not difficult either to manufacture or procure pure
sodic thiosulphate, a portion is taken, powdered, and dried between
blotting paper and 24'S grams weighed. This quantity is then
136 THE BREWER'S ANALYST
dissolved in a little distilled water, transferred to a litre flask, and
made to mark at 60 F. (15*5 C.) with distilled water. .
The solution should be titrated with decmormal iodine solution,
using a little gelatinised starch as an indicator. It should
N
correspond, volume for volume, with iodine solution.
The solution is prone to decompose, depositing sulphur, especially
if not kept in the dark. This tendency may be obviated, according
to Mohr, by adding about 2 grams sesquicarbonate of ammonia.
O'Shaughnessy states that the addition of a little salicylic acid
entirely prevents the solution decomposing.
DECINORMAL SODIC CHLORIDE ( J
= 5'85 grams NaCl per litre
1 c.c. = 0-003537 gram Cl
0-005837 NaCl.
5'85 grams of pure sodic chloride dissolved in distilled water and
made up to 1 litre at 60 F. (15'5 C.).
POTASSIC NITRATE.
1-011 gram KN0 3 per litre
1 c.c. = 0'14 milligram N.
Dissolve 1*011 gram pure potassic nitrate and make to 1 litre
at 60 F. (15-5 C.) with distilled water.
There is no simple volumetric method for checking this solution.
If iu doubt, make up a fresh one, as this will involve less time
than the exact titration of the old solution.
INDIGO SOLUTION.
1 c.c. = 0-0001 gram N
0-000386 N 2 5 .
Weigh 4 grams pure soluble indigo carmine in a small beaker ;
mix in a few drops of cold distilled water to form a paste, and
then add 4 c.c. of strong sulphuric acid. Cover the beaker and
allow to stand all night. Dilute with water, thoroughly mix, and
make up at 60 F. (15'5 C.) to 1 litre.
The solution keeps for a lengthy period, but should be
standardised against a standard solution of potassic nitrate (TO 11
PREPAKATION OF STANDARD AND OTHER SOLUTIONS 137
gram of the crystallised salt in 1 litre of distilled water). 5 c.c.
of the nitrate solution is diluted to 50 c.c. with distilled water,
sulphuric acid run in, and titration performed with the indigo as
described under Water Analysis. 5 c.c. of the nitrate solution
should require exactly 7 c.c. of the indigo.
Indigo solution to be used for tannin estimations need not be
of exact strength.
ARGENTIC NITRATE.
4 '79 grams AgN0 3 per litre
1 c.c. -0-001 gram Cl
0-00165 NaCL.
Dissolve 4'79 grams pure recrystallised argentic nitrate in a
little distilled water, transfer to a litre flask, and make to mark at
60 F. (15-5 C.) with distilled water.
N
The solution should be titrated against sodic chloride, using
potassic chromate as indicator.
A decinormal solution may be prepared, if required, by
dissolving 17 grams of the silver nitrate and diluting to 1 litre.
Each c.c. will then equal 0'010766 gram Ag.
0-016966 AgN0 3 .
IRON SOLUTION.
1 c.c =0*1 milligram Fe.
Weigh 0'7 grain ferrous-ammonia sulphate, transfer to a boiling
flask, dissolve in about 300 c.c. of distilled water, add about 5
drops nitric acid, and boil for about 10 minutes in order to oxidise
the iron. Cool the solution, transfer to a litre flask, wash in the
rinsings from the boiling flask, and make to mark at 60 F.
(15-5 C.) with distilled water.
The formula of the ferrous-ammonia sulphate is Fe(NH 4 ) 2
(S0 4 ) 2 60H 2 = 392. Consequently, it contains exactly one-
seventh of its weight of iron; 0*7 gram therefore represents
O'l gram of iron, and this is a convenient quantity to weigh
for the purpose of titrating permanganate solution hereafter
referred to.
The solution is not permanent, and should be titrated before
use. When freshly prepared, 100 c.c. of it should require 5 -35
c.c. of permanganate.
30
138 THE BREWER'S ANALYST
THIRTIETH NORMAL POTASSIC PERMANGANATE ( ).
\30/
1 c.c. = '001385 tannic acid.
Add 333*3 c.c. decinormal potassic permanganate to a litre
flask and make to mark at 60 F. (15'5 C.) with distilled water
free from ammonia.
The solution should be titrated against oxalic acid, 30 c.c.
N
requiring 10 c.c. oxalic.
SODIC THIOSULPHATE FOR FORSCHAMMER'S OXYGEN PROCESS.
Weigh 2 grams pure recrystallised sodic thiosulphate, transfer
to a litre flask, dissolve in a little distilled water, and make to
mark at 60 F. (15'5 C.) with distilled water.
N
The solution may be titrated against iodine.
POTASSIC IODIDE FOR FORSCHAMMER'S OXYGEN PROCESS.
Weigh 100 grams pure potassic iodide, dissolve in a little
distilled water, transfer to a litre flask and make to mark at
60 F. (15'5 C.) with distilled water free from ammonia. The
solution is not required to be very exact ; it may be titrated,
however (in the same way as a chloride), with silver nitrate, using
potassic chromate as indicator : 5 c.c. of iodide should equal 30*1
N
c.c. silver solution.
POTASSIC PERMANGANATE FOR FORSCHAMMER'S OXYGEN PROCESS.
1 c.c. = '0001 gram available oxygen.
Dissolve 0'395 gram pure dry potassic permanganate and make
to a litre at 60 F. (15*5 C.) with distilled water free from
ammonia.
N N
The solution may be titrated against oxalic acid : 5 c.c.
oxalic requires 40 c.c. permanganate.
So long as the solution is quite free from sediment, it may be
taken for granted that its strength is unaltered.
STANDARD AMMONIA.
Dissolve 3*15 grams ammonic chloride and make to 1 litre at
60 F. (15*5 C.) with distilled water free from ammonia.
PEEPARATION OF STANDARD AND OTHER SOLUTIONS 139
The solution should be titrated against the silver nitrate
solution previously described (4*79 grams AgN0 3 per litre), 10
c.c. requiring 20*9 c.c. of the silver solution.
DILUTE STANDARD AMMONIA.
1 c.c. = '01 milligram NH 3 .
Take 10 c.c. of the standard ammonia solution previously
described and dilute to 1 litre with distilled water at 60 F.
(15-5 C.).
The solution should be freshly prepared at least once a month.
NESSLER'S SOLUTION.
Dissolve 62-5 grams potassic iodide in about 250 c.c. distilled
water, set aside a few c.c., and add gradually to the larger part a
cold, saturated solution of corrosive sublimate until the iodide of
mercury precipitated ceases to be redissolved on stirring. When
a permanent precipitate is obtained, restore the reserved potassic
iodide so as to redissolve it, and continue adding corrosive
sublimate gradually until a slight precipitate remains undissolved.
(The small quantity of potassic iodide is set aside merely to
enable the mixture to be made rapidly without danger of adding
an excess of corrosive sublimate.)
Next dissolve 150 grams potassic hydrate in 150 c.c. distilled
water, allow the solution to cool, add it gradually to the above
solution, and make up with distilled water to 1 litre.
On standing, a brown precipitate is deposited, and the solution
becomes clear and of a pale, greenish-yellow colour. It is ready
for use as soon as it is perfectly clear, and should be decanted into
a bottle as required.
WATER FREE FROM AMMONIA.
When determining the amount of free or saline ammonia in a
water, the sample is distilled which causes the free or saline
ammonia, if present, to come off with the distillate. For this
reason distilled water usually contains a considerable quantity of
free ammonia and should therefore be tested before use. Unless
free, it is useless to employ it for making up standard ammonia
solutions or for Nesslerising purposes. If a good tap- water is at
hand, showing no reaction of ammonia, it may be employed for
Nesslerising, but failing the possession of such a water, it becomes
140 THE BREWER'S ANALYST
necessary to prepare distilled water free from ammonia ; whilst
owing to tap- water containing, as a rule, large quantities of saline
bodies, it should not, even if free from ammonia, be employed for
making up standard solutions.
It is an easy matter to expel the free ammonia from distilled
water by vigorously boiling it in a capacious flask for about 30
minutes ; the water being afterwards cooled and transferred to a
bottle ready for use.
On the other hand, ordinary tap-water may be distilled rejecting
the distillate so long as any colour is produced by Nessler's re-
agent ; or the water in the retort may be acidulated with pure
sulphuric acid, when the whole distillate will be free from ammonia
and in all other respects pure.
ALKALINE POTASSIC PERMANGANATE.
Dissolve 200 grams potassic hydrate and 8 grams crystallised
potassic permanganate with 800 c.c. distilled water in a large
porcelain dish and evaporate over water-bath almost to dryness.
This effectually expels all traces of ammonia. Cool, transfer to
a litre flask, and make to mark at 60 F. (15'5 C.) with distilled
water free from ammonia.
AMMONIA MOLYBDATE SOLUTION.
Dissolve 4 grams molybdenum trioxide (Mo0 3 ) in 94 c.c.
ammonia (sp. gr. 0'880) and 150 c.c. distilled water; filter into
694 c.c. strong nitric acid (sp. gr. 1*2), dilute to a litre with a
1 2 per cent, solution of nitric acid ; stand about 1 2 hours at
122 F. (50 C.) and then filter through three folded papers and
bottle.
MAGNESIA MIXTURE.
Dissolve one part of crystallised magnesic sulphate and two
parts ammonic chloride in eight parts of distilled water and four
parts strong ammonia.
Allow the mixture to stand for several days and then filter and
bottle.
FEHLING'S SOLUTION.
Volumetric.
50 c.c. = '24 gram dextrose.
25 invert.
40 maltose.
PREPARATION OF STANDARD AND OTHER SOLUTIONS 141
Gravimetric.
I gram CuO = '4535 dextrose.
'4715 invert.
7435 maltose.
The solution consists of copper sulphate, potassic sodic tartrate
(Rochelle salt), and sodic hydrate, and it was formerly customary
to make and keep the solution in one bottle ready for use. It
was found, however, that the mixed solution would not keep, but
that under certain conditions, namely, provided the copper
sulphate is made up as a separate solution and slightly acidified,
it will keep sound for an almost indefinite period, whilst the
alkaline solution kept separately will also keep for a lengthy
period. The latter solution is not, however, so permanent as the
copper sulphate, but as it need not be of accurate strength, it
becomes an easy matter to prepare fresh solutions from time to
time.
Two solutions are therefore now employed, viz., copper
sulphate solution and alkaline tartrate, and are prepared as
follows :
Copper Sulphate Solution. About 70 grams of crystallised
copper sulphate are powdered and pressed between blotting paper;
69-28 grams are then carefully weighed and dissolved in about
400 c.c. distilled water, about 4 c.c. concentrated sulphuric acid
then added, and the solution made to 1 litre at 60 F. (15'5 C.)
with distilled water.
The solution should be standardised as hereafter described.
Alkaline Tartrate Solution. 346 grams of Rochelle salt
and 130 grams of caustic soda are dissolved in about 800 c.c.
distilled water, cooled, and made to 1 litre at 60 F. (15-5 C.)
with distilled water. The solution should then be allowed to
stand for 24 hours, and be afterwards filtered through a funnel
containing a plug of glass wool.
Standardisation. Volumetric. It is necessary to first
prepare a standard solution of invert-sugar as follows :
The purest variety of cane-sugar is that known as coffee-sugar,
which generally contains from 99 to 99-8 per cent, of absolute
sugar. The large crystals of this sugar should be selected, and
after examining a solution in the polarimeter or determining the
moisture percentage by drying a portion in the water oven,
2 grams of actual sugar should be weighed, that is, making
allowance for the amount of moisture.
The 2 grams of actual sugar are now placed in a 200 c.c.
142 THE BREWER'S ANALYST
4.
flask, 50 c.c. of distilled water and 5 c.c. of hydrochloric acid
added, and the whole maintained at a temperature of 150 F.
(65*5 C.) on the water bath for 20 minutes. By this time the
sugar will have been inverted to dextrose or invert-sugar ; the
flask is then cooled and the solution neutralised by the addition
4.
of 5 c.c. alkali, the bulk being afterwards made up to 200 c.c.
at 60 F. (15-5 C.) and a Fehling's test performed with some of
the sugar solution in order to determine the quantity of Fehling's
required. Having determined this, and knowing by calculation
what quantity correct Fehling's should require, we may ascertain
the dilution necessary to bring the copper sulphate solution to the
proper strength.
Example. The coffee-sugar taken was found by the polari-
meter to contain 99 "6 per cent, of real cane sugar; 2 grams of
sugar were required, so 99'6 : 100 : : 2 : 2'OOS. 2-008 grams of
the sugar were weighed and inverted with 5 c.c. acid,
N
4.
neutralised with 5 c.c. alkali and diluted to 200 c.c. Every
95 parts of cane-sugar on inversion become 100 parts of invert,
hence 95 : 100 : : 2 : 2*10 grams invert-sugar in 200 c.c. and
2-10-^2 = 1-05 in 100 c.c.
If 100 c.c. contain 1*05 gram of invert-sugar, how many c.c.
will contain *25 gram? the quantity corresponding to 50 c.c.
Fehling's.
1-05 : 100 : : -25 : 23-8.
Therefore 23*8 c.c. of the sugar solution are required to reduce
50 c.c. Fehling's.
We now conduct a Fehling's test in order to ascertain if this
is so or what the actual strength of the Fehling's is. To do this
it should be remembered that the sugar solution experimented
with should not contain more than 1 per cent, of sugar. In our
example it will be noted that 2 grams of sugar diluted to 200
c.c. equals a 1 per cent, solution, so that the sugar solution is not
above the maximum concentration for a Fehling's test. We
therefore take 200 c.c. of distilled water in a boiling flask of about
800 c.c. capacity and boil. When well boiled, 50 c.c. Fehling's
solution are added, that is, 25 c.c. of the standard copper solution
and 25 c.c. of the alkaline tartrate.
The contents of the flask are again raised to the boiling-point,
and 10 c.c. of the 1 per cent, sugar solution are run in from a
PREPARATION OF STANDARD AND OTHER SOLUTIONS 143
graduated burette. The whole is again boiled for about two
minutes, and further quantities of the sugar solution are added
at the rate of 5 c.c. at a time, the boiling being continued after
each addition until a bright red colour, due to the formation of
cuprous oxide (CuO), is obtained. The flask is now removed and
set aside for the precipitate to settle. If the flask is now held to
the daylight, the colour may readily be seen ; should any blue
tinge remain, more sugar solution, 1 c.c. at a time, is added, and
the boiling recommenced and continued until the blue colour
just disappears. To test whether the reduction of the copper is
complete, a little of the solution is withdrawn by a glass rod
and brought at once in contact with a drop of ferrous thiocyanate
on a porcelain or opal glass slab.
It is always advisable to test before it is thought that the
Fehling's is quite completed, as it is impossible to tell how much
it is overdone, but absolutely easy to ascertain the incompletion.
If it has been overdone, it is necessary to repeat the estimation
over again with fresh Fehling's and further quantities of the
sugar solution. It is almost impossible to hit the exact point
on the first trial, but it affords a very good guide for a
more exact titration the second time, and a second titration
should always be made. When the titration is once com-
menced it should be carried on as quickly as possible, in order
to prevent irregularities from long exposure of the hot solution
to the atmosphere.
The reduction being complete, the number of c.c. of sugar
solution used is read off from the burette. Let us assume
we have used 31*4 c.c. sugar solution. We have seen from
the calculation that 23'8 c.c. of the invert-sugar solution
should reduce 50 c.c. Fehling's ; but it is here found that
31 '4 c.c. were required, so that the Fehling's solution is too
strong.
What factor does 31 '4 c.c. correspond to?
23-8 : -25 : : 31'4 : '320.
Therefore each 50 c.c. of Fehling's, or 25 c.c. of copper solution,
equal '320 invert-sugar instead of *25.
How many c.c. of correct standard copper solution should
represent -320 grams ?
If 25 c.c. equal '25, how many c.c. does '320 equal 1
25 : 25 : : -320 : 32'0 c.c.
So we have merely to dilute 25 c.c. of our Fehling's solution
144 THE BREWER'S ANALYST
to 32 c.c. to bring it to proper strength, or add to each 25 c.c.
that are left 7 c.c. of distilled water.
For particulars of gravimetric estimation, see p. 213, Malt
Wort Analysis.
SOLUBLE STARCH (DRY).
Take about 1 Ib. purified potato starch, place in a clean
Winchester quart bottle, and add 1000 c.c. of a 7'5 per cent,
solution of hydrochloric acid (75 c.c. hydrochloric acid, specific
gravity 1037-0, and 925 c.c. distilled water). Set aside the
mixture at the room temperature 60-65 F. (15-5 -18'3 C.)
for seven days, stirring daily. 1
At the end of this time wash thoroughly by decantation, at
first with tap-water, and later on with pure distilled water, until
the washings are free from chloride neutral to freshly prepared
litmus paper.
Now collect the starch on a filter paper, place in a Buchner's
funnel, pump as dry as possible, and then spread it out on a new
unglazed porous plate. The starch should now be dried at a
gentle heat 110 F. (43'3 C.), as quickly as possible and then
triturated in a porcelain mortar and rubbed through a fine hair
sieve.
SOLUBLE STARCH SOLUTION FOR LINTNER'S DIASTATIC PROCESS.
The previously prepared dry soluble starch is dissolved in
boiling water at the rate of 2 grams per 100 c.c. of water. The
solution is then cooled to 70 F. (21'1 C.) for use. It should be
perfectly mobile (not gelatinous), indicating perfect conversion
into soluble starch, and show only a negligible reducing action
on Fehling's solution. It should be neutral to litmus solution,
and the distilled water employed for making up the solution
should be absolutely pure.
POTASSIC PERMANGANATE FOR HOP TANNIN PROCESS.
Dissolve 1 gram pure dry potassic permanganate in a little
distilled water and make to 1 litre with distilled water at a
temperature of 60 F. (15'5 C.). The distilled water should be
free from ammonia.
1 According to Brown and Morris (Jnl. Chem. Soc., 1889, 450), if a 12
per cent, solution of hydrochloric acid is employed, 24 hours' digestion
suffices.
PREPARATION OF STANDARD AND OTHER SOLUTIONS 145
The solution may he titrated against decinormal oxalic acid :
N
10 c.c. oxalic should require 31 '6 c.c.
INDIGO SOLUTION FOR HOP TANNIN PROCESS.
Dissolve 5 grams pure indigo carmine in 500 c.c. distilled
water ; add 50 c.c. concentrated sulphuric acid, cool, and make
to 1 litre at 60 F. (15'5 C.) with distilled water. Each c.c. of
this solution should correspond to an equal amount of the
previously prepared potassic permanganate.
GELATINE SOLUTION FOR HOP TANNIN PROCESS.
Weigh 25 grams Nelson's gelatine, place in a beaker, add
250 c.c. distilled water, and set aside for about 6 hours. Now
heat on the water bath until the gelatine is dissolved ; next
saturate with fairly pure sodic chloride and make up to 1 litre
at 60 F. (15'5 C.) with a saturated solution of sodic chloride.
Shake the solution, allow to stand for a few days, warm, and then
filter bright into a bottle ready for use.
BOTTLES (10 PER CENT. SOLUTIONS).
Plumbic acetate. Sodic phosphate.
Baric chloride. ,, carbonate.
,, hydrate. ,, hydrate.
Ammonic chloride. ,, bisulphate.
,, oxalate. Potassic hydrate.
,, carbonate. ,, ferrocyanide.
phosphate. ,, chromate (free from Cl).
,, nitrate. iodide.
Potassic chloride.
Sulphuric acid, dilute (1-3).
Hydrochloric acid, dilute (1-3).
Acetic acid, dilute (1-1).
Ammonic hydrate, dilute (1-3).
10
146
THE BREWER'S ANALYST
TABLE FOR THE SYSTEMATIC ANALYSIS OF ALKALIES, ALKALINE
EARTHS, AND ACIDS.
|
Quantity to be
weighed so that
Substance.
Formula
Atomic
Weight
1 c.c Normal
Solution =
Normal
Factor. 1
1 per cent, of
Substance.
grams.
Ammonia .
NH 3
17
1-7
0-017
Ammonic carbonate
Acetic acid .
(NH 4 ) 2 C0 3
G 2 O 2 H 4
96
60
4-8
6'0
0-048
0-060
Baric hydrate
BaH 2 2
171
8-55
0-0855
,, (crystals)
Ba0 2 H 2 (OH 2 ) 8
315
15-75
0-1575
,, carbonate .
BaC0 3
197
9-85
0-0985
Calcic oxide
CaO
56
2-8
0-028
,, hydrate .
CaH 2 2
74
3-7 -
0-037
,, carbonate .
CaC0 3
100
5-0
0-050
Citric acid .
C 6 7 H 8 + OH 2
210
7-0
0-070
Hydrochloric acid
HCL
36-5
3-65
0-0365
Magnesia
M 9
40
2-00
0-022
Magnesic carbonate
M 9 C0 3
84
4-20
0-042
Nitric acid .
HN0 3
63
6-3
0-063
Oxalic acid .
C 2 4 H 2
126
6-3
0-063
Potash
K 2
94
47
0-047
Potassic hydrate .
KHO
56
5-6
0-056
carbonate
,, bicarbonate .
K 2 C0 3
KHC0 3
138
100
6-9 0-069
10-0 . 0-100
Soda ....
Na^O
62
3-1 0-031
Sodic hydrate
NaHO
40
4-0 0-040
,, carbonate .
, , bicarbonate
Na,C0 3
NaHC0 3
106
84
5-3 0-053
8-4 0-084 -
Sulphuric acid .
H 2 S0 4
98
4-9 i 0-049
Strontia
SrO
103-5
5-175 0-05175
Strontic carbonate
SrC0 3
147-5
7-375 0-07375
Tartaric acid
C 4 6 H 6
150
7-5 0-075
1 This is the coefficient by which the number of c.c. of normal solutions
used in analysis is to be multiplied in order to obtain the amount of pure
substance present in the material examined. See also Multipliers required in
Volumetric Analysis, p. 394.
PART VI.
METHODS OF ANALYSIS.
OF the various chemical preparations offered for sale to brewers,
it is necessary to know how much pure substance they contain.
Let us first take, for instance, the various acids :
SULPHURIC ACID.
Take 10 c.c. of concentrated white sulphuric acid in a tared
crucible and weigh. Suppose the weight is found to be 18*27
grams; then this, divided by 10, gives the specific gravity, viz.
1-827.
In consequence of the great concentration and high specific
gravity of sulphuric acid, it is best to use only 1 or 2 c.c. for
analysis ; hence, after the specific gravity is ascertained, 2 c.c.
may be titrated, taking care that a very fine and accurate
pipette is used for the purpose ; or, if this is not at hand, the acid
may be weighed direct upon the balance.
Suppose we take 2 grams of the above acid in a porcelain dish,
dilute with distilled water, add a few drops of methyl-orange or
litmus solution, and titrate with normal alkali, 37 '2 c.c. of the
alkali being required ; then
37-2 x 0-049 (coefficient table) = 1'822, and
l-822x 1QQ = 91 percent> hydrated acid,
which agrees with Otte's table (p. 401).
HYDROCHLORIC ACID.
Take 5 c.c. of white hydrochloric acid in a tared crucible and
weigh. Suppose the weight to be 5'6 grams; then this, divided
by 5, gives the specific gravity as 1'12.
147
148 THE ETC EWER'S ANALYST
Dilute with distilled water and titrate with normal alkali,
using a few drops of methyl-orange or litmus as indicator.
N
Suppose 37"! c.c. - - alkali are required; this, multiplied by
0-0365 (coefficient table), gives 1'354 grams.
hydrated acid
5*6
Ure's table (p. 402) gives 24"46 per cent, for the same specific
gravity.
In order to ascertain the percentage of hydrochloric acid gas
in any sample, it is only necessary to multiply the weight of gas
found by normal alkali by 100, and divide by the weight of
acid originally taken for analysis : the quotient will be the
percentage. Or, simpler than this, if the ^ equivalent in grams
3"646 grams be weighed, the number of c.c. will be the per-
centage.
NITRIC ACID.
Take 5 c.c. of pure nitric acid and weigh. Suppose the weight
to be 6 '055 grams; this, divided by 5, gives the specific gravity
N
as 1'211. Say the quantity of alkali required to saturate the
5 c.c., using methyl-orange as indicator, is 28'3 c.c. This, multi-
plied by the coefficient factor 0*063, gives 1*782.
1-782x100
6-055
= 29'4 per cent.
ACETIC ACID.
In consequence of the anomaly existing between the specific
gravity of acetic acid and its strength, the hydrometer gives no
uniformly reliable indication of the latter, and consequently the
volumetric method is peculiarly suitable for ascertaining the
value of acetic acid in all its forms. For most purposes normal
caustic alkali may be used as the saturating agent ; but a slight
error occurs in this method, from the fact that neutral acetates
have an alkaline reaction on litmus ; the error, however, is very
small, if care be taken to add the alkali till a distinct blue colour
is reached. As acetic acid is volatile at high temperatures,
normal carbonate of soda must not be used for titrating it, as it
would necessitate heat to expel the carbonic acid.
Five c.c. of acetic acid weighs, say, 5'206 grams -{-5=1-041
specific gravity. The quantity of normal alkali required to
METHODS OF ANALYSIS 149
saturate it is, say, 27'1 c.c.; then this multiplied by 0*06 (co-
efficient) = 1*626 grams.
1-626 x 1QO:
-T206- = 31 ' 2 P
For the ordinary vinegar or turned beer there is no necessity
to take the specific gravity into question : 5 or 10 c.c. may be
taken as 5 or 10 grams. It is advisable to copiously dilute highly
coloured liquids, in order that the change in the colour, produced
by the litmus, may be distinguished ; recourse must also be had
to litmus paper, upon which little streaks should be made from
time to time with the stirring rod.
SULPHUROUS ACID.
N
1 c.c. iodine = 0'0032 gram S0 2 .
N
1 c.c. thiosulphate = 0'01265 gram iodine.
1. Take 20 c.c. of the acid in a 200-c.c. flask and make to
mark at 60 F. (15'5 C.) with recently boiled and cooled distilled
water. Take 10 c.c. of this in a porcelain dish, add a few drops
of freshly prepared gelatinised starch solution, 1 and titrate with
decinormal iodine until a blue colour makes its appearance and
becomes permanent on stirring.
N
Suppose 2 3 '3 c.c. iodine are required to produce the blue
colour. Then 23-3 x -0032 (factor) = 0'0745xlOO = 7-45 per
cent, sulphurous acid.
2. It is invariably found that the result is below the truth,
for not only is oxidation proceeding during the time occupied in
adding the iodine, but volatilisation of the free sulphurous acid
also, to a slight extent, takes place. The source of error may
be reduced by conducting a second titration, running into a
porcelain dish containing distilled water and gelatinised starch
solution the amount of iodine consumed in the first instance
(23'3 c.c.), and then adding to this the 10 c.c. of dilute sulphurous
acid. A further addition from the burette of as much as 1 c.c.
iodine may have to be made in order to produce the blue colour.
The result would therefore be 24*3 c.c. instead of the previously
mentioned 2 3 -3 c.c.
1 See footnote, p. 172.
150 THE BREWER'S ANALYST
The exactness of the method may, however, be still further
ascertained by the following method:
3. Take 10 c.c. of the prepared dilute acid solution in a
porcelain dish, and add a few drops of gelatinised starch solution.
In the first experiment 23'3 c.c. iodine were required, we
therefore now add this quantity, together with an extra 5 c.c.
N
= 28'3 c.c., and titrate with thiosulphate.
N
Suppose 7*1 c.c. thiosulphate are required to change the
blue colour; then
7'1 x -01265 (factor) = -0898 x 100 = 8'98 percent, sulphurous acid.
However, 5 c.c. extra iodine have been used, which are equal
to 1-60 per cent. (5 x "0032 = -0160 x 100), so that 1'60 from
the above 8'98 = 7'38 per cent. ; and as the amount found in the
first experiment with iodine was 7 '45 per cent., the one experiment
confirms the accuracy of the other, and the acid may be said to
contain 7 '45 per cent, of sulphurous acid.
Thiosulphate solutions are prone to change ; it is advisable,
therefore, to make a blank experiment with iodine ; and if this be
done, it is of no importance that the thiosulphate be strictly
decinormal, since its exact value, as compared with iodine, is
easily calculated, and the multiplier '01265 merely altered
accordingly.
The principle of this beautiful method of analysis, discovered
by Dupasquier, consists in the fact that free iodine converts
sulphurous into sulphuric acid by decomposing water, the oxygen
of which goes to the sulphurous and produces sulphuric acid ;
the hydrogen, being taken by the iodine, forming hydriodic acid.
The reaction between iodine and very dilute sulphurous acid
is represented by the formula
S0 2 + 1 2 + 20H 2 = 2H1 + H 4 S0 4 .
Bunsen found that the solution should not contain more than
0'5 per cent, of sulphur dioxide, since, if above this strength, the
action is reversed, the irregularity of decomposition varying with
the quantity of water present, and the rapidity with which the
iodine is added. This irregularity is, however, now obviated, as
shown by Mohr, by the use of ammonic, potassic, or sodic
bicarbonate, which have no effect upon iodide of starch. Either
of these salts, added in moderate quantity to the liquid sulphurous
acid, or, in case of sulphites, dissolving them in the alkaline
METHODS OF ANALYSIS 151
solution previous to titration with iodine, overcomes the difficulty
hitherto found in concentrated solutions.
This method can be applied to the determination of a great
variety of substances with extreme accuracy.
Bodies which take up oxygen, and decolorise the iodine solu-
tion, such as sulphurous acid, sulphites, sulphuretted hydrogen,
alkaline thiosulphates, etc., are brought into dilute solution,
gelatinised starch solution added, and the iodine delivered in with
constant stirring until a point occurs at which a final drop of
iodine colours the whole blue a sign that the substance can
take up no more iodine, and that the drop in excess has shown
its characteristic effect upon the starch.
In diluting the liquid acid or in dissolving sulphites, etc., the
distilled water employed for dilution should be well boiled and
cooled, since, as shown by Giles and Shearer, 1 the air dissolved
in the water used for dilution interferes with the accuracy of the
results. They adopt, therefore, the method of placing the
sulphite in a known excess of iodine, and determining such
excess by means of sodic thiosulphate.
Commercial sulphurous acid purchased by brewers for cleansing
purposes, fining manufacture, etc., should always be purchased
at a definite specific gravity, a convenient gravity being about
10-33.
AMMONIA.
Take 10 c.c. ammonia and weigh. Suppose the weight to be
9'67 grams ; this, divided by 10, gives the specific gravity as 0'967.
The quantity of normal acid required to saturate the 10 c.c.,
using methyl-orange as indicator, is, say, 46 c.c. ; then this
multiplied by 0'017 (coefficient) = 0'782
' 782xl( L8per cent, ammonia (NH 8 ).
y *u i
Carius's table, 0'967 specific gravity, gives 8 per cent. (p. 405).
SODIC CARBONATE.
If it were absolutely pure, 5 '3 grams of it should require exactly
100 c.c. acid to effect neutralisation. If we therefore weigh
that quantity, bring it into solution with distilled water, add a
1 Jnl. Soc. Chem. Ind., April 1884.
152 THE BREWER'S ANALYST
few drops of phenacetolin as indicator, and deliver into the
mixture normal hydrochloric acid from a 100 c.c. burette, the
number of c.c. required to saturate it will show the percentage
of pure sodic carbonate in the sample.
Suppose 90 c.c. acid are required. Then the sample contains
90 per cent, sodic carbonate.
As a further example 90 c.c. x '053 (coefficient factor) = 4*77.
477 x 100 nn
= 90 per cent.
O'o
Suppose, on the other hand, it is required to know the equiva-
lent percentage of
DRY CAUSTIC SODA,
free and combined, contained in the above sample of soda ash.
This may be ascertained by calculation thus :
The sample contains 90 per cent, of sodic carbonate.
Sodic oxide =62
Sodic carbonate = 106
= 0-585
90 x 0'5S5 = 52 '65 per cent, sodic oxide.
Again, instead of calculating the result, we may proceed as
follows :
Weigh 3'1 grams of the soda ash, bring it into solution with
water, add a few drops of phenacetolin, and titrate with normal
acid; the number of c.c. acid required to saturate it is the
percentage of sodic oxide.
Example :
N
Reading acid = 5 2 '6 c.c. = 52 '6 per cent, sodic oxide, or
90 per cent, carbonate. 1
ALKALINE SOLUTIONS.
From the nature of the substance, or its being in solution, the
percentage method previously employed cannot here be con-
veniently followed. For example, suppose we have a solution
which from the flame coloration is seen to be potash a weighed
or measured quantity of it is brought under the acid burette and
saturated exactly by normal hydrochloric acid, using phenacetolin
as indicator.
1 52-6 x -031 (coefficient factor) = 1 '630. 3'1 : 1'630 : : 100 : 52'6 per cent,
sodic oxide or 90 per cent, sodic carbonate.
METHODS OF ANALYSIS 153
It is advisable, owing to the usual high strength of these
solutions, to weigh or measure only about 5 c.c. and dilute
largely with distilled water so that the reaction may be clearly
observed.
Supposing, of 5 c.c. taken, the amount of normal hydrochloric
acid employed to saturate it is 37 c.c. The molecular weight of
potassic hydrate being 56, 100 c.c. - hydrochloric acid will
5*6 x 37
saturate 5*6 grams, therefore - = 2'072 ; and as 5 grams of
the solution were taken, 2*072 x 20 = 41*44 per cent. KHO.
On the other hand, suppose the specific gravity of the solution
is found to be 1 '380 ; this, by Tiinnermann and Richter's table
(p. 404), is equal to 41*37 per cent., against our 41*44 per cent,
found by titration.
With soda solutions we preceed in precisely the same manner.
For example, we have a solution which by the colour flame is seen
N
to be soda. Of 5 c.c. taken, the amount of hydrochloric acid
employed to saturate it is, say, 23 c.c.
N
The molecular weight of sodic oxide being 62, 100 c.c. of hydro-
6*2 x 23*0
chloric acid will saturate 6*2 grams, therefore lnn = 1*426 :
and as 5 c.c. were taken, 1*426 x 20 = 28*52 per cent.
Na 2 0.
The specific gravity is found, say, to be 1 *40 ; according to
Tiinnermann's table (p. 404) = 28*40 per cent, against our
28'52 per cent, by titration.
WATER ANALYSIS.
The following are the determinations to be made
1. Total solids.
2. Saline residue.
3. Organic and volatile matter.
4. Lime.
5. Magnesia.
6. Sulphuric acid.
7. Chlorine and chloride of sodium.
8. Iron.
9. Alkalinity before and after boiling.
10. Soda and potash.
154 THE BREWER'S ANALYST
Nitrogen as Nitrates and Nitrites :
11. Nitric acid.
12. Nitrous acid.
Organic Matter :
13. " Free or saline " ammonia.
1 4. " Albuminoid " ammonia.
15. Oxygen required to oxidise organic matter.
The following further tests are sometimes necessary :
16. Silica.
17. Lead.
18. Copper.
19. Bacteriological examination (see p. 369).
WATER ANALYSIS.
Collection of Samples.
Every precaution should be taken to ensure the collection of a
truly representative sample. Stoneware bottles should be avoided,
as they are apt to affect the hardness of the water, and are more
difficult to clean than glass. Stoppered glass bottles should be
used where convenient; those known as "Winchester Quarts,"
which hold about two-and-a-half litres each, are very handy and
easy to procure. One of these will hold sufficient for the general
analysis of a water, whilst two are ample for all purposes, including
a bacteriological examination, should such be required.
If corks are used, they should be netv, and well washed with
the water at the time of collection.
In collecting from a well, river, or tank, plunge the bottle itself,
if possible, below the surface ; but if an intermediate vessel must
be used, see that it is thoroughly clean and well rinsed with the
water. Avoid the surface water and also any deposit at the
bottom. If the sample is taken from a pump or tap, take care to
let the water which has been standing in the pump or pipe run
off before collecting, then allow the stream to flow directly into
the bottle.
If it is to represent a town water supply, take it from the
service pipe communicating directly with the street main, and
not from a cistern.
In every case, first fill the bottle completely with the water,
empty it again, rinse once or twice carefully with the water, and
then fill it nearly to the stopper and tie down tightly.
At the time of collection note the source of the sample, whether
from a deep or shallow well, a river, or spring. If it is from a
METHODS OF ANALYSIS 155
well, ascertain the nature of the soil, subsoil, and water-bearing
stratum, the depth and diameter of the well, its distance from
neighbouring cesspools, drains, or other sources of pollution;
whether it passes through all impervious stratum before entering
the water-bearing stratum, and if so, whether the sides of the well
above this are, or are not, water-tight.
If the sample is from a river, ascertain the distance from the
source to the point of collection ; whether any pollution takes
place above that point, and the geological nature of the district
through which it flows.
If from a spring, take note of the stratum from which it
issues.
In order to ensure uniformity, the bottle should invariably be
well shaken before taking out a portion of the sample for the
purpose of analysis.
Colour.
A very tolerable opinion may be formed as to whether a sample
of water contains unchanged organic matter by comparing its
colour with that of distilled water ; to this end Lovibond's
tintometer may be used, or, failing this, two white glass cylinders
about 12 or 18 inches high should be placed upon white paper or
a white porcelain slab, one filled with distilled water and the
other with the sample to be tested, side by side : any yellow or
brown colour in the sample indicates the presence of organic
matter, but it may not necessarily be owing to very objectionable
impurity, since purely vegetable matter such as peat will often
produce it.
Smell.
The smell can be observed by shaking up some of the water in
a large, wide-mouthed flask or bottle, and applying the nose to
the bottle immediately afterwards. If the water be warmed to a
slight extent, any objectionable smell is more readily detected.
Filtration.
Before commencing the quantitative analysis, it is necessary
to decide whether the water shall be filtered or not. This must
depend on the purpose for which the examination is undertaken.
As a general rule, if the suspended matter is to be determined,
the water should be filtered before the estimation of ammonia and
total solid residue ; if otherwise, it should merely be shaken up.
If the suspended matter is not determined, the appearance of
the water, whether clear or turbid, should be noted.
156 THE BEEWER'S ANALYST
Water derived from a newly sunk well, or which has been
rendered turbid by the introduction of innocuous mineral matter
from some temporary and exceptional cause, should be filtered ;
but the suspended matter, in most cases, particularly with
brewery well waters, need not be determined.
Suspended Matter.
From a sanitary point of view suspended matter is of minor
interest, because it may be in most cases readily and completely
removed by nitration. Mineral suspended matter is, however,
of considerable mechanical importance as regards the formation
of impediments in the river-bed by its gradual deposition, and as
regards the choking of niters and the binding effect it has with
the saline bodies causing incrustation in boilers.
1. Total Solids. Evaporate over the water bath half a litre
(500 c.c.) or a less quantity of the water, measured at 60 F.
(15*5 C.), in a platinum dish which has been heated to redness,
cooled under the desiccator, and carefully weighed.
As soon as the evaporation is complete, the dish with the
residue is removed from the water bath, its outer side wiped dry
with a cloth, and then dried in the oven for about three hours.
It is then placed under the desiccator, allowed to cool, weighed
as rapidly as possible, returned tu the oven, dried, copied, and
again weighed at intervals of an hour until the weight is constant.
Example :
Weight of platinum dish and solids . 70 '41 4 grams.
Weight of platinum dish . . . 60'420
9-994
A gallon of water weighs 10 Ibs. or 70,000 grains ; when taking
500 c.c. multiply by '2 to bring to 100 c.c., and by '7 to obtain
the number of milligrams in 70 c.c., which for the purpose of
calculation is reckoned as a miniature gallon. Milligrams per
70 c.c. equal grains per gallon; hence 9*994 x -2 = T9988 x '7 =
1-39916 = 13-9916 grains solid matter in 70 c.c., or 139'92
grains per gallon total solid matter.
2. Saline Residue. Having obtained the weight of the total
solid matter, the platinum dish containing it is placed over a gas
flame and gently ignited. If, on being heated, the solid residue
darkens, it indicates a large amount of organic matter ; and if it
becomes black, the water is highly contaminated. The ignition
is carried on for about half a minute until the residue is quite
METHODS OF ANALYSIS 157
white or brown, the latter showing the presence of iron. The
dish is then cooled, the residue recarbonated, by moistening it
with a drop or two of ammonic carbonate, and again gently
heated over the gas flame, care being taken that the carbonate is
not driven off during the heating. The dish is once more cooled
under the desiccator and again weighed at intervals until constant.
Example :
Weight of platinum dish and saline
residue ..... 69 '380 grams.
Weight of platinum dish . . . 60'420
8-960
8-960 x -2 = 1-7920 x -7 = 1-2544, or 125'40 grains per
gallon saline residue.
3. Organic and Volatile Matter. The difference between
the total solid matter and the saline residue, thus :
Total solid matter = 139*920 grains per gallon.
Saline residue = 125 '400
14*520 grains per g-allon
organic and volatile matter.
4. Lime. Take 500 c.c. of the water at 60 F. (15'5 C.) in
a large beaker, add 5 or 6 drops of hydrochloric acid, and boil
down to about half bulk. Now add about 20 c.c. of 10 per cent,
solution ammonic oxalate, about 10 c.c., 10 per cent, ammonic
chloride, and about the same quantity of 10 per cent, ammonic
hydrate, which cause the lime to separate in the form of calcic
oxalate. 1 The liquid should now be set aside and allowed to
1 The object of the addition of ammonic hydrate is as follows :
Lime may be precipitated in neutral or fairly acid solution by ammonic
oxalate, but the precipitation is in such case incomplete. In ammoniacal
solutions, however, the precipitation is perfect.
The addition of ammonic chloride is unnecessary for the separation of calcic
salts, but it is added to prevent the simultaneous precipitation of magnesia,
which also forms an insoluble oxalate, but not in the presence of ammonic
chloride. A quantity of ammonic oxalate should therefore be added sufficient
not only to convert the calcic, but also the magnesic, salts into oxalates.
Fresenius shows that in the presence of large quantities of magnesia this
process is not rigidly accurate, but that a small quantity of this body pre-
cipitates along with the lime ; and further, that unless a large excess of
ammonic oxalate is present, the lime is not completely precipitated. He
considers a re-solution and precipitation of the calcic oxalate a necessity, but
waters as a rule do not contain sufficient magnesia to render such operation
necessary.
158 THE BREWER'S ANALYST
stand for not less than 3 hours, by which time the precipitation
will be complete and the supernatant liquid bright.
Nearly the whole of the liquid is now carefully filtered into a
clean dry beaker, through a filter paper previously moistened
with water, the precipitated insoluble calcic oxalate, together with
the small quantity of liquid left in the beaker, being then stirred
up by means of a glass rod to the end of which is attached a
small piece of rubber tube ; the liquid is then passed on to the
filter, the beaker being rinsed with distilled water, any particles
of calcic oxalate being removed by the glass rod, and the repeated
washings in this manner transferred to the filter until every
particle of the oxalate has been transferred to the filter. The
filter paper is now washed by sparging successive portions of
boiling distilled water from the wash bottle, and these wash-
ings also collected in the beaker containing the filtrate. If
the filtrate is cloudy, it must be again returned to the filter
paper and filtered until perfectly brilliant; there is, however,
seldom any difficulty in this respect with a filtration of a lime
precipitate.
The filtrate from the lime is required for the subsequent
estimation of magnesia, and is therefore set aside until required.
The filter paper containing the calcic oxalate is now placed in
the water oven and dried, after which it is carefully folded, put
in a tared crucible, and placed on a tripod over a Bunsen flame
and the oxalate burned to a white or grey ash, the oxalate by
this ignition being reduced to carbonate. Very slight heat is
sufficient to decompose calcic oxalate into calcic carbonate, but
small quantities of carbon - dioxide are disengaged from the
carbonate so that it is advisable to " recarbonate." This is
effected by moistening the ash, after cooling, with two or three
drops of ammonic carbonate solution, then carefully drying on
the water bath, and finally gently heating for a moment or two
over a small flame. Any carbon-dioxide which may have been
volatilised in the first heating is thus replaced at the expense of
the ammonic carbonate, while the excess of the latter is volatilised
on drying in the water bath and subsequent exposure to gentle
heat over the flame.
The crucible is now placed under the desiccator to cool and
is then weighed, the ash being again recarbonated, dried, cooled,
and weighed until the weight is constant. The amount of calcic
carbonate (CaC0 3 ) so found is now calculated to that of calcic
oxide (CaO).
The atomic weight of CaC0 3 is 100, and that of CaO 56,
METHODS OF ANALYSIS 159
therefore every 100 parts of CaCO 3 contain 56 parts of CaO; the
quantity of calcic oxide is therefore calculated as follows :
56 x CaC0 3 found
"100
Or the same thing is arrived at by multiplying the CaC0 3 found
by -56.
Example :
Weight of crucible and precipitate . 8-027 grams.
Weight of crucible .... 7 '564
CaC0 3 -463
Then -463 x -2= "0926 grams CaC0 3 in 100 c.c.
0926 x -7 = -06482 CaC0 3 in 70 c.c. ; or
64'82 grains per gallon CaC0 3 , and
64-82 x -56 = 36-33 grains per gallon of lime (CaO).
5. Magnesia. To the filtrate from the lime add about 10 c.c.
of 10 per cent, solution ammonic or sodic phosphate and about
10 c.c. of strong ammonic hydrate, well stir, and allow to stand
for 6 hours, or preferably over-night. Filter, wash the pre-
cipitate with dilute ammonia, dry, place in a tared crucible, and
strongly ignite to a grey ash; cool under desiccator and weigh
as pyrophosphate of magnesia 2(MgO)P 2 5 .
The atomic weight of 2(MgO)P 2 O fi is 222, and that of 2MgO,
80; every 222 parts of the pyrophosphate therefore correspond
to 80 of magnesia, or
-52.-.-M.
222
The factor -36 may be employed to convert the one into the other.
Example :
Crucible and precipitated pyrophos-
phate 7'765 grams.
Crucible . ... 7-564
201
Then -201 x -2 = -0402 x 7 = -02814 per 70 c.c.
So that 28-14 x *36 = 10*15 grains per gfallon mag'-
nesia (Mg-0).
6. Sulphuric Acid. Take 500 c.c. of the water at 60 F.
(15*5 C.) in a large beaker, add three or four drops of hydro-
chloric acid, boil to half bulk, and add about 15 c.c. of 10 per
160 THE BREWER'S ANALYST
cent, solution baric chloride. Boil for a further two or three
minutes and then set aside in a warm place so that the baric
sulphate may settle. When the supernatant liquid is clear,
filter l and wash the precipitate thoroughly with boiling distilled
water. Now place the filter containing the precipitate in the
water oven to dry, then ignite to a white ash in a tared crucible,
cool under the desiccator and weigh, repeating ignition, cooling,
and weighing until the weight is constant.
Example :
Weight of crucible and baric sulphate . 8 '739 grams
Weight of crucible .... 7'650
1-089
Therefore 1 -089 x '2 = 2'178 x -7 = 1-5246 per 70 c.c., or 15'246
grains per gallon BaS0 4 .
It now remains to ascertain the quantity of sulphuric anhy-
dride corresponding to the weight of baric sulphate obtained.
The atomic weight of BaS0 4 is 233, and that of sulphuric anhy-
dride (S0 3 ), 80 ; 233 parts of baric sulphate therefore correspond
80
to 80 parts of sulphuric anhydride, hence - = '343 ; so that
2oo
we have merely to multiply by the factor '343. Thus 15'24G
grains per gallon BaSO 4 x -343 = 52 "29 grains per gallon
sulphuric anhydride (SO*).
7. Chlorine and Chloride of Sodium. To 250 c.c. of the
water at 60 F. (15*5 C.) in a large porcelain dish, add two or
three drops 10 per cent, potassic chromate (free from chlorine), so
as to give it a faint tinge of yellow, and add gradually from a
burette standard argentic nitrate solution (p. 137) until the red
argentic chromate which forms after each addition of the nitrate
ceases to disappear on stirring.
The chromate is simply an indicator, the affinity of silver for
chlorine being greater than that for chromic acid ; hence no
chromate of silver is found until the chlorides in the water are
used up.
Where extreme accuracy is desired, after completing a deter-
mination, destroy the slight red tint by an excess of a soluble
chloride, and repeat the estimation on a fresh quantity of the
1 It is sometimes difficult to obtain a clear filtrate owing to the sulphate
forming a very finely divided precipitate ; this may be avoided by the addition
at the time of adding the baric chloride, of about '005 gram of potato starch
which has a conglomerating action upon the precipitate and retains it on the
filter paper. Repeated filtration, however, is effectual.
METHODS OF ANALYSIS 161
water in a similar porcelain dish placed by the side of the
former. By comparing the contents of the dishes, the first
tinge of red in the second dish may be detected with great
accuracy.
It is absolutely necessary that the liquor examined should not
be acid, unless from carbonic acid, nor more than slightly alkaline.
It must also be colourless or nearly so. These conditions are
generally found in waters ; but, if not, they may be brought about
in most cases by rendering the liquid just alkaline with lime
water (free from chlorine), passing carbonic anhydride to satura-
tion, boiling, and filtering. The calcic carbonate has a powerful
clarifying action, and the excess of alkali is exactly neutralised by
the carbonic anhydride. If this is not successful, the water must
be rendered alkaline, evaporated to dry ness, and the residue
gently heated to destroy organic matter. The chlorine may
then be extracted with distilled water and estimated in the
ordinary way.
Example. 8 '5 c.c. argentic nitrate solution were required to
produce the reddish tint in 250 c.c. of the water. Then S'5 x '4 =
3-40 x -7 = 2*38 milligrams chlorine per 70 c.c. or grains
per gallon.
In order to convert chlorine to sodic chloride :
The atomic weight of chlorine (Cl) is 35 '5, and that of sodic
chloride (NaCl) 58*5. Every 35 '5 parts of chlorine therefore
K Q , K
correspond to 58'5 parts of sodic chloride, hence - = 1*645;
oO'D
so that we multiply by the factor 1'645, or, to simplify matters, by
1-65. Thus 2-38 grains per gallon chlorine x 1'65 = 3'92 grains
per gallon sodic chloride.
8. Iron. Take 70 c.c. of the water at 60 F. (15-5 C.) in a
small boiling flask, add 1 c.c. concentrated nitric acid (the
presence of free acid is always necessary in this process in order
to convert iron existing in the water in a ferric state to that of
the ferrous state), and boil for 5 minutes. Cool to 60 F.
(15*5 C.), transfer to a Nessler tube, and make up to 70 c.c.
with distilled water. Add a drop or two of 10 per cent, solution
potassic ferrocyanide, when, if iron is present, a blue colour will
appear which is then imitated by a standard solution of iron
(p. 137), added to a similar bulk of distilled water in a Nessler
tube until the colour matches that of the sample, when both tubes
are looked through while standing on a white surface.
The exact strength of the iron solution being known (1 c.c. =
O'l milligram Fe), it is easy to arrive at the quantity of pure iron
11
162 THE BREWER'S ANALYST
present in the water, and to convert it into its state of combina-
tion by calculation.
Example. In this case 1'4 c.c. of the standard iron solution
were required to imitate the blue colour, each c.c. being equiva-
lent to O'l milligram of iron.
1*4 x '1 = '14 milligram of iron in 70 c.c.
or '14 grain per gallon.
It is usual, however, to express the iron as ferric oxide (Fe 2 3 ),
112
so that as 160 parts Fe 2 3 equal 112 parts of iron, i- =0-7. We
have merely to multiply O'l 4 by 0'7 to obtain the amount of
ferric oxide, which, therefore, equals 0*098 grain per gallon
Fe 2 3 .
This method, which approaches in delicacy the Nessler test
for ammonia, is applicable for very minute quantities of iron ;
in fact, 1 part of iron in 13,000,000 parts of water can thus be
detected.
9. Alkalinity before and after Boiling 1 . This estimation
is merely carried out as a check upon the accuracy of other
analytical results, and is of great importance, particularly with
waters containing carbonate of soda or potash.
Thus, after combining the acids and bases we have, say, a
certain quantity of calcic carbonate, and a certain quantity of
magnesic carbonate. By now finding the equivalent of the
magnesic carbonate and expressing it as calcic carbonate, this;
added to the actual amount of calcic carbonate originally found,
shows the total alkalinity of the water ; which, if the same as the
alkalinity estimated by this test, shows that the analysis in this
respect is correct. If, however, there is a deficiency, then the
analysis is incorrect ; whilst if there is an excess, it shows that
such excess is due to carbonate of soda or potash.
The estimation is made as follows :
(1) Measure 350 c.c. of the water at 60 F. (15'5 C.), run into
N
a large beaker and titrate with acid, using two or three drops
of methyl- orange as an indicator. Say, for instance, that 32*2 c.c.
acid were required to produce the faint pink coloration.
(2) A further 350 c.c. of the water at 60 F. (15 "5 C.) are now
measured out into a large beaker and boiled for three-quarters of
an hour. The liquid is then filtered through a paper previously
moistened with boiling distilled water, the beaker rinsed with
METHODS OF ANALYSIS 163
distilled water, and the washings transferred to the filter. The
filtrate, after cooling, is now titrated with - acid, using methyl-
orange as an indicator. Say, for example, that T6 c.c. acid
were required to produce the faint pink coloration.
Now the difference between these two titrations is due to the
precipitation of carbonate of lime during boiling, with perhaps a
trace of carbonate of magnesia. Lime is not, however, absolutely
insoluble in boiling water, but remains in solution to the extent
of 1 4 26 grain per gallon, and this figure may therefore be taken
into account when calculating the result. If 350 c.c. of the water
N
are employed, each c.c. of acid corresponds to one grain of
carbonate of lime per gallon.
Example :
N
350 c.c. unboiled water required . 32*2 c.c. acid.
350 c.c. boiled and filtered water 1'6
Alkalinity removed by boiling . 30'6
grains per gallon CaC0 3 . To this figure is added 1*26 (solubility
of CaC0 3 in boiled water) = 31*8 grains per gallon CaC0 3 .
10. Soda and Potash. Take 500 c.c. of the water at 60 F.
(15'5 C.) in a beaker and boil down to about 50 c.c. Add baric
hydrate until the liquid is alkaline (about 10 c.c.), and set aside in
a warm place (on the water bath) for one hour. Filter and wash
the precipitate well with hot distilled water. To the filtrate add
about 5 c.c. of 10 per cent, ammonic chloride and ammonic
carbonate until no more barium is precipitated (probably about
10 c.c.).
The barium precipitates the bases except the alkalies soda
and potash ; and the ammonic chloride and carbonate precipitate
the excess of barium, leaving the alkalies in solution as chlorides.
Now allow to stand for 2 hours, then filter and wash with
hot distilled water, after which boil the filtrate down to about 25
c.c. ; transfer to a clean platinum dish and evaporate to dryness.
When dry, gently ignite until ammoniacal fumes cease to be given
off, but taking care not to heat too strongly for fear of volatilising
small quantities of chlorides. Cool under the desiccator and
weigh ; repeat ignition, cool, and again weigh. Now extract the
residue with warm distilled water and filter. Return the filter
paper to the platinum dish, ignite, cool, and weigh.
164 THE BREWER'S ANALYST
The difference between the former weight (which is the tare of
the dish and traces of insoluble substances) and this one gives
sodium and potassium as chlorides. It now remains to separate
these alkalies. This is performed by adding 5 c.c. of platinic
bichloride to the nitrate, which is then evaporated to dryness,
dried at 212 F. (100 C.), cooled, and weighed until constant.
The gain in weight is due to potash existing as potassic platinic
chloride (KCl 2 )PtCl 4 . The potassic chloride being thus found,
the quantity of sodic chloride is then calculated.
Example :
Weight of platinum dish + solids before
extraction '. 62'570 grams.
Weight of platinum dish + solids after
extraction .... 62"462 ,,
108
108 x -2 = -0216 x -7 = 15-120 grains per gallon total chlorides.
After treatment with platinic chloride :
Weight of platinum dish + solids . 60-450 grams.
Weight of platinum dish . . 60'418
032
032 x -2 = -064 x '7 = -0448 ; therefore potassic platinic chloride
= 4'48 grains per gallon and 4'48 x 307 1 = 1*375 grain per gallon
potassic chloride.
Total alkalies . . 15*120 grains per gallon.
Potassic chloride . . 1'375
Sodic chloride . . 13*745
NaCl 13-745 x '53 = 7-25 grains per gallon Na 2 0.
KCL 1-375 x -63 = 0-86 K 2 O.
It will be seen that the estimation of soda and potash is rather
tedious, and by no means easy. Frequently, owing to incomplete
separation of other bodies, the alkalies come out too high, and this
error is attributed to the soda, owing to the potash being sub-
sequently determined.
1 (KCl 2 )PtCl 4 = 484'5 gives 2KC1 = 1487, therefore 1 = '307.
2 j 2NaCl = 1167 gives Na 2 = 62'0, therefore 1 = '53.
i 2KC1=1487 gives K 2 = 94'0, therefore 1 = "63.
METHODS OF ANALYSIS 165
NITROGEN AS NITRATES AND NITRITES.
By far the best test for estimating nitrogen as nitrates and
nitrites in water is that known as the mercury method, but it has
the great disadvantages of requiring costly gas-analysis apparatus,
of being complicated, and, in inexperienced hands, yields poor
results. The indigo method about to be described is the one now
generally resorted to, and when carefully performed gives excellent
results. In fact the following will show the difference in the
results obtained by the two processes :
Parts per 100,000.
With Mercury. With Indigo.
1 . . 0-973 ' . . . 0-912
2 . . 4-235 . . . 4-530
3 . 1-825 . . . 1-706
4 . . 0-729 . . . 0-676
5 . . 2-749 . . . 2-912
6 . . 1-696 . . 1-294
7 . . 2-144 . . 2-265
8 . . 0-354 . . . 0-338
9 . . 2-860 . . 2-824
10 . . 0-222 . . . 0-221
The indigo process was originally devised by Marx 1 and
improved by Warrington. 2
The principle of the method is that of liberating free nitric and
nitrous acids from their combinations by the aid of strong
sulphuric acid, and measuring the quantity so liberated by the
decoloration of a solution of indigo.
The accuracy of the method is disturbed in the presence of
much chlorides, so that for such cases an alternative method,
Gladstone and Tribe's, is also given.
11. Estimation of Nitric Acid : Marx Indigo Process.
Take 50 c.c. of the water at 60 F. (15'5 C.) in an 8 ounce flask
and add an equal bulk of pure strong sulphuric acid, allowing
the acid to run down the side of the flask and avoiding mixing
the solutions as far as possible. Now agitate the contents of the
flask and rapidly add, from a burette, a standard solution of
indigo (p. 136), until a permanent faint bluish-green tint is
perceptible. Read off the number of c.c. of indigo consumed,
and as each c.c. corresponds to 0*1 milligram of nitrogen, the
1 Zeitschr.f. ang. Chem., vol. viii. 412.
- Jnl. Chem. Soc. Trans., xxxv. 578.
166 THE BREWER'S ANALYST
amount of nitrogen in the 50 c.c. of the water is found by
multiplying by '01.
To find from this the corresponding amount of nitric acid is
a simple matter. Two atoms of nitrogen (N 2 ) are contained in
the molecule of nitric anhydride (N 2 O 5 ) ; the calculation there-
fore is :
N 2 =28 N 2 5 =108
108 x N found ~
Or, by dividing the atomic weight of N 2 into that of N 2 O 5 , the
factor 3 '86 is obtained, which gives the amount of nitric acid
(anhydrous) from the nitrogen found; and the result is then
calculated to grains per gallon.
Example. 50 c.c. of water took 2*3 c.c. indigo solution
2'3 x 2 = 4-6 x -7 = 3-22 per 70 c.c. water; 3'22x'l = '322 gram
N per gallon; -322 x 3'86 = 1'25 grain per gallon nitric
anhydride.
Estimation of Nitric Acid: Gladstone and Tribe's
Method. This method was introduced by Gladstone and Tribe J
twenty-eight years ago, and its application to water analysis was
fully dealt with in 1881 by W. Williams. 2 It is accomplished
as follows :
Take 250 c.c. of the water at 60 F. (15-5 C.) in a porcelain
dish, add two or three drops of caustic potash solution which
must be free from ammonia, evaporate over the water bath ta
about 50 c.c., and then transfer to a small flask, the cork of
which is provided with a thistle-headed funnel and stop-cock.
Wash the porcelain dish with distilled water, and add the
rinsings to the flask so as to make up the bulk to about 20 c.c.
Now add a few pieces of copper-coated zinc. 3 Connect the flask
to a distilling apparatus and arrange the exit of the condenser
tube with a glass tube passing to the bottom of a 100 c.c. flask
in which has been placed 1 or 2 c.c. of distilled water and a
single drop of hydrochloric acid. Now heat the flask gently
for one hour (do not boil) and then distil the contents until
nearly the whole has evaporated ; then fill up the funnel with
hot distilled water and turn on the stop-cock, allowing the
whole to pass over into the 100 c.c. flask. Repeat addition
of water to the flask and continue distillation until about
90 c.c. have been collected. Remove the 100 c.c. flask,
1 Jnl. Chem. Soc., 1878, 140. 2 Ibid., 1881, 100.
3 Granulated zinc is immersed in strong copper sulphate solution until
metallic copper is deposited on the surface of the zinc.
METHODS OF ANALYSIS 167
dilute to mark with distilled water free from ammonia,
agitate, take 5 c.c., dilute to 50 c.c., and Nesslerise as ex-
plained (p. 169).
Each equivalent of ammonia found corresponds to one equiva-
lent of nitric acid; that is to say, each 17 parts of ammonia
correspond to 54 parts of nitric acid ;
So that by multiplying the ammonia found by the factor 3 '176,
we get the nitric acid, and the result is calculated to grains per
gallon.
Example. 250 c.c. of water taken and 5 c.c. of the distillate
(after diluting to 50 c.c.) required 7'0 c.c. of standard ammonia
to produce equivalent colour value. 7'0 x '01 = '070 milligram
of NH 3 in the 5 c.c. or 1'40 in the whole distillate containing the
ammonia from the nitric acid in 250 c.c. of the water. Then
1-40 x -4= '560 milligrams of NH 3 in 100 c.c. x '7 = '3920 in
70 c.c., i.e. "3920 grain per gallon NH 3 due to nitric acid. This
multiplied by 3-176 = 1 '25 grain per gallon nitric an-
hydride.
12. Nitrous Acid: Greiss's Method of Detection. 1 It is
only in very impure waters that nitrous acid is found, and even
in these cases it generally exists in quantity too minute for
quantitative estimation.
The author has never yet found nitrous acid in a deep well
water, and believes that where it has been detected in such waters
it is due more to the system adopted than to the fact of its
existence.
The simplest method of detection is that proposed by Greiss,
which consists in the addition of meta-diamido-benzene to the
water after acidifying, which imparts a yellow colour with the
most minute traces of nitrous acid. 100 c.c. of the water are
taken in a Nessler tube, 1 c.c. of strong sulphuric acid added,
and then a few drops of meta-diamido-benzene solution. The
tube, after standing for a few minutes, is then examined by
looking down through it, on a white porcelain tile or piece of
white paper.
Nitrous Acid: Fresenius's Method of Estimating-.
The following method is given by Fresenius 2 for the quantitative
1 For full particulars of Greiss's method, see paper by R. Warrington, Jnl.
Chem. Soc., 1881, 229.
2 Fresenius's Quantitative Analysis, Churchill.
168 THE BKEWER'S ANALYST
estimation should nitrites be present in quantity in a water,
which is seldom the case :
Take 250 c.c. of the water at 60 F. (15'5 C.), acidify by the
addition of a few drops of acetic acid, place in a retort and distil
off about 100 c.c., collecting the same in a 250 c.c. flask and
making up the distillate to mark with distilled water.
A portion of this distillate is then taken, acidified with a few
drops of pure sulphuric acid, and titrated against a very weak
solution of potassic permanganate, 30 c.c. of which should equal
'01 gram of iron = '0034 nitrous anhydride ^N T 2 3 .
Organic Matter. We are indebted to Wanklyn, Chapman,
and Smith for the now well-known "albuminoid ammonia
process " of estimating the quantity of nitrogenous organic matter
in water, which dates from the year 1867. 1
The method depends upon the conversion of the nitrogen in
such organic matter into ammonia when distilled with an alkaline
solution of potassic permanganate. The authors have given the
term "albuminoid ammonia" to the NH 3 produced from nitro-
genous matter by the action of permanganate, doubtless because
the first experiments made in the process were made with
albumin ; but they also proved that ammonia may be obtained
in a similar manner from a great variety of nitrogenous organic
substances, such as hippuric acid, narcotine, strychnine, morphine,
creatine, gelatine, casein, etc. Unfortunately, however, although
the proportion of nitrogen yielded by one substance when treated
with boiling alkaline permanganate appears to be definite, yet
different substances give different proportions of their nitrogen.
Thus hippuric acid and narcotine yield the whole, but strychnine
and morphine only one-half of their known proportions of
nitrogen. Hence the value of the numerical results thus obtained
depends entirely on the assumption that the nitrogenous organic
matter in water is uniform in Its nature, and the authors say
that in a river polluted mainly by sewage "the disintegrating
animal refuse would be pretty fairly measured by ten times the
albuminoid ammonia which it yields."
They also state that " the albuminoid ammonia from a really
good drinking water should not exceed O'OOS parts per 100,000."
The average of fifteen samples of Thames water supplied to
London by the various Water Companies some years ago was
0'0089, and in five samples supplied by the New River Company
0-0068 parts per 100,000. The rapidity and simplicity of the
operation are the chief merits of this process, and the information
1 Jnl. Chem. Soc. N.S., vol. v. 591.
METHODS OF ANALYSIS 169
to be obtained from its performance may, for some purposes, be
of considerable value ; and even if the numerical results cannot
be insisted upon, yet a good water could not be condemned by it,
and a bad one should not escape its indications.
There are two estimations to be made, viz. :
13. Free or saline ammonia.
14. Albuminoid ammonia.
13. Estimation of Free or Saline Ammonia. Half a
litre (500 c.c.) of the water at 60 F. (15-5 C.) is measured and
added to a retort, together with 10 c.c. of a saturated solution of
sodic carbonate. The retort is then connected with a Liebig
distilling apparatus (fig. 35, p. 31), condensing water turned on,
and a Bunsen-flame placed close under the bottom of the retort
and lighted full on. The distillation soon commences, and the
distillate should be received in a tall glass cylinder of about
150 c.c. capacity, and marked at 50 c.c. and 100 c.c.
Four such cylinders are required at hand during the operation.
When 50 c.c. have distilled over, the cylinder should be
removed and a fresh cylinder placed to receive a further 50 c.c.
of the distillate.
Whilst this second cylinder is slowly receiving the second
50 c.c. distillate, the free or saline ammonia contained in the
first 50 c.c. should be tested. 1
In order to perform this, a standard tube is first made up as
follows :
NESSLERISING.
To a tall glass cylinder of a capacity of 150 c.c., marked at
50 c.c. and 100 c.c., similar to those employed for the collection
of the. distillate, but graduated at each 5 c.c., is added from a
burette 5 c.c. of standard ammonia (p. 139), and then made up
to 50 c.c. with water free from ammonia (p. 139) 2 and mixed.
One c.c. of Nessler's solution (p. 139) is then added, and the
whole mixed. One c.c. of Nessler's solution is at the same time
added to the 50 c.c. distillate, and both this tube and the
1 It is inadvisable to allow the tubes containing the distillate to remain
standing in the laboratory for any length of time, as (water being very
absorbent) ammoniacal or sulphuretted hydrogen fumes may be absorbed and
thus vitiate the results
2 Distilled water invariably contains a large percentage of ammonia, and
therefore, if not previously freed from the same, should not be used. Good
tap-water will usually be found free, and may, therefore, in most cases be
employed.
170 THE BREWER'S ANALYST
standard tube are now placed on a white surface, such as a
white tile, and allowed to stand for 5 minutes. By this time
a yellow or brown colour will be produced in the distillate,
varying in intensity with the amount of free ammonia contained
in the water, and the object is to imitate the colour in the
standard tube.
The two tubes are therefore taken and examined side by side.
If the colour in the standard tube is too deep, withdraw sufficient
solution, so that, on looking down the tubes on to the white surface,
the colours are exactly of the same intensity. Note the amount
of standard ammonia required. If the colour is darker than that
of the standard, a fresh standard of double strength should be
made. The second 50 c.c. distillate is now taken and Nesslerised
in a similar manner; a third 50 c.c. distillate collected and
Nesslerised, and again a fourth 50 c.c. if necessary. Three
separate 50 c.c.'s, however, usually suffice with most waters.
Generally speaking, the whole of the free NH 3 will come over in the
first 100 or 150 c.c., but the distillation should be continued
until 50 c.c. of the distillate contain less than j-^ milligram of
NH 3 .
Wanklyn has recommended the uniform plan of Nesslerising
only the first 50 c.c. for free ammonia, throwing away the 150 c.c.
subsequently distilled, and calculating that it contains one-third
of the quantity found in the first 50 c.c.
14. Estimation of Albuminoid Ammonia. To the contents
of the retort left from the operation just described, are at once
added, through a clean funnel inserted into the tubulure of the
retort, 50 c.c. alkaline permanganate (p. 140). Having added this,
resume the distillation, and estimate the ammonia as before until
no more is evolved ; generally speaking, it is sufficient to distil
150 c.c. after adding the alkaline permanganate, estimating the
ammonia in each 50 c.c. The boiling is often very irregular,
especially in bad waters, and if so it is advisable to introduce into
the retort a few small pieces of freshly ignited pumice or pipe-
clay to moderate the bumping. It is always advisable to
incline the neck of the retort upwards, so that the liquid carried
up by spirting may be returned ; especially as manganese com-
pounds in particular have a powerful effect upon the colour pro-
duced by the Nessler solution, generally intensifying it> and thus
vitiating results. The amount of ammonia estimated by the
Nessler test in this distillate is entered as albuminoid ammonia.
The number of c.c. of standard ammonia required to imitate
the colour intensity in each tube are now added together, and
METHODS OF ANALYSIS 171
the result calculated and expressed in parts per million as
follows :
The graduated tube contained 5 c.c. of standard ammonia (O01
milligram per c.c.), 50 c.c. therefore contain 0'05 milligram of
ammonia.
Free Ammonia
1st tube, 50 c.c. distillate
from NaC0 3 = 42 c.c. standard ammonia.
2nd tube, 50 c.c. distillate
from NaC0 3 = 19
3rd tube, 50 c.c. distillate
from NaCCL = Nil.
61 c.c. total to equal tint.
Now 50 c.c. = '05 milligram of ammonia, therefore '061
milligram is present in the 61 c.c. ; that is, in 500 c.c. of the water,
or -122 per 1000 c.c. of water. Now 1000 c.c. contain 1,000,000
milligrams, therefore milligrams per 1000 c.c. = parts per million.
The sample therefore contains 0'122 parts per million Of
free ammonia.
Albuminoid Ammonia (calculated in the same way) :
1st tube, 50 c.c. distillate from
potassic permanganate = 19 c.c. standard ammonia.
2nd tube, 50 c.c. distillate from
potassic permanganate = 12 ,,
3rd tube, 50 c,c. distillate from
potassic permanganate = Nil.
31 c.c. total.
31 c.c. = '031 milligram of ammonia in 500 c.c., or 0*062
milligram in 1000 c.e. or parts per million.
Jf it is desired to express the result in parts per 100,000, instead
of in parts per million, it is written thus :
Free ammonia =0'012.
Albuminoid ammonia = 0*006.
15. Oxygen required to oxidise Organic Matter. This
process, originally designed by Forschammer and reintroduced by
Tidy, depends upon the estimation of the amount of oxygen
absorbed in oxidising the organic and other oxidisable matters in
172 THE BREWER'S ANALYST
a known volume of water, when slightly acidified with sulphuric
acid.
For this purpose a standard solution of potassic permanganate
(p. 138) is used in excess; the amount unoxidised after a given
time being ascertained by the help of a standard solution of sodic
thiosulphate (p. 138), by the aid of the well-known iodide of starch
reaction.
Ferrous salts, nitrites, or sulphuretted hydrogen, if present in
the water, also decompose the permanganate ; but as organic matters
are only slowly oxidised, the bodies named affect the permanganate
almost immediately. Therefore, by conducting two experiments,
one after standing 15 minutes, the other after standing 4 hours,
the reduction of the permanganate due to iron, nitrites, etc., and
that due to organic matter, may be determined.
The estimation is performed as follows :
A stoppered bottle of about 300 c.c. capacity is carefully rinsed
out with dilute sulphuric acid and well rinsed afterwards with
distilled water. Ten c.c. of standard potassic permanganate and
200 c.c. of the water are then added, and afterwards 10 c.c. of
dilute sulphuric acid, which is first rendered a faint pink by the
addition of a few drops of the permanganate.
The bottle, with the stopper replaced, is then set aside on the
forcing tray and maintained at about 75-80 F. (23-8-26'6 C.) for
4 hours.
At the end of this time, the undecomposed permanganate is
determined as follows :
One or two drops of potassic iodide solution are added to the
water in the bottle, which change the pink colour to yellow, due
to the liberation of the free iodine. Standard thiosulphate
solution is now run in from a burette until the yellow colour has
nearly, but not quite, disappeared. A few drops of freshly
prepared gelatinised starch solution l are now added, which turn
the solution blue. The thiosulphate is then again added to the
solution until the blue colour is just destroyed. The quantity of
thiosulphate used is noted. Let us denote this as A.
As the thiosulphate solution is liable to slightly change upon
keeping, a blank experiment is now made to determine its value.
This is performed by taking 200 c.c. distilled water, 10 c.c. of the
standard permanganate, and 10 c.c. of dilute sulphuric acid made
faintly pink with permanganate. A drop of potassic iodide is
1 Gelatinised starch, prepared by mixing about 1 gram of potato starch with
about 80 c.c. distilled water, boiling for a few minutes, cooling, and making
up to about 100 c.c.
METHODS OF ANALYSIS 173
added, which changes the colour to yellow, and the solution is
again titrated with the thiosulphate solution. This gives the
value of the thiosulphate solution. Let us denote this as B.
A further experiment is now performed with a further 200 c.c. of
the water, with the addition of permanganate and acid as before,
but allowed to stand 15 minutes, after which a drop of potassic
iodide is added and the solution titrated wit thiosulphate as
before described. Let us denote this by C.
From the results of the three experiments the amount of
oxygen absorbed is thus obtained :
A. 200 c.c. of water after 4
hours required 9'3 c.c. thiosulphate solution.
C. 200 c.c. of water after 15
minutes required 10'8 ,,
B. Blank experiment required 11 '4 ,, ,,
1T4 equals 10 c.c. permanganate, therefore 9'3 = 8'1
10x9-3
=o'i
11-4
and 10 - 8'1 = 1 '9 permangante absorbed in 4 hours.
Similarly, as 11*4 equals 10 c.c. permanganate, 10-8 equals 9'5,
and 10-9'5 = 0'5 permanganate decomposed in 15 minutes.
Each c.c. of the standard permanganate equals 0*1 milligram of
available oxygen, so that the above figures correspond to '19 and
05 milligram respectively per 100 c.c. of water.
It is usual, however, to express the results in terms of parts
per 100,000, so that as 100 c.c. contains 100,000 milligrams,
we get :
Oxygen absorbed in 15 minutes . . . '025
Oxygen 4 hours . . '095
16. Silica. It is only in exceptional circumstances that the
estimation of silica is necessary ; such, for instance, as when the
water is seen to contain an excess of suspended or deposited
matter. In such instances the estimation is carried out as
follows :
To 500 c.c. of the water at 60 F. (15-5 C.) add a few drops of
hydrochloric acid, and evaporate by degrees to dry ness in a
platinum dish. Heat to 300 F. (14S'8 C.), cool, add a few
more drops of hydrochloric acid and about 50 c.c. distilled water.
Stir the residue by the aid of a rubber-tipped glass rod and allow
to stand when the silica precipitates.
Filter, wash the precipitate with distilled water, dry the filter
174 THE BREWER'S ANALYST
paper and its contents in the water bath, ignite, cool under
desiccator, and weigh.
Example :
Weight of platinum dish + Si0 2 . . . 9'688
Weight of platinum dish . . 9 '685
003
0030 x -4 = -001 20 x -7= -00084.
= 0'84 grain per gallon.
17. Lead. Add 50 c.c. of the water at 60 F. (15 -5 C.) to a
Nessler tube, acidulate with a few drops of acetic acid, and then
run in 10 c.c. of saturated aqueous solution of sulphuretted
hydrogen.
Compare the colour thus produced in a similar cylinder with a
known quantity of a standard solution of lead acetate in a manner
similar to that described for the estimation of iron.
The lead solution may be prepared so as to contain 0'183 gram
of normal crystallised plumbic acetate in a litre of distilled water
at 60 F. (15-5 C.) ; each c.c. will therefore correspond to '001
gram of metallic lead.
18. Copper. Of the coloured reactions which copper gives
with different reagents, those with sulphuretted hydrogen and
potassic ferrocyanide are by far the most delicate, both showing
their respective colours in 2,500,000 parts of water. Of the two
reagents sulphuretted hydrogen is the more delicate ; but potassic
ferrocyanide has a decided advantage over sulphuretted hydrogen
inasmuch as lead, when not present in too large quantity, does
not interfere with the depth of colour obtained, whereas to sul-
phuretted hydrogen it is, as is well known, very sensitive. And
though iron if present would, without special precautions being
taken, prevent the determination of copper by means of potassic
ferrocyanide, yet, by the method here described, the copper in a
solution can be estimated by this reagent. Ammonic nitrate
renders the reaction much more delicate ; other salts, such as
ammonic chloride and potassic nitrate, have likewise the same
effect.
The method of analysis consists in the comparison of the
purple-brown colours produced by adding to a solution of potassic
ferrocyanide first, a solution of copper of known strength ; and
secondly, the solution in which the copper is to be determined.
To 100 c.c. of the water at 60 F. (15'5 C.) add two or three
drops of nitric acid and evaporate to dryness in a platinum dish.
METHODS OF ANALYSIS 175
Ignite the residue to get rid of any organic matter that may
colour the liquid, and dissolve in a little boiling distilled water
and a drop or two of nitric acid ; if the residue is not all soluble, it
does not matter. Ammonia is next added to precipitate the iron,
the latter filtered off, washed, redissolved in nitric acid, and again
precipitated by ammonia, filtered off, and washed. The filtrate is
added to the one previously obtained, and the copper estimated
in the united filtrates after rendering the liquid neutral.
The liquid must be neutral, for, if it contain free acid, the
latter lessens the depth of colour and changes it from a purple-
brown to an earthy brown. If it should be acid, it is rendered
slightly alkaline with ammonia, and the excess of the latter got
rid of by boiling. The solution must not be alkaline, as the
brown coloration is soluble in ammonia and decomposed by potash
or soda. If it be alkaline from ammonia, this is removed by
boiling; while free potash or soda, should they be present, are
neutralised by an acid and the latter by ammonia.
Example. Two Nessler tubes are taken and into each is run five
drops of potassic ferrocyanide. Fifty c.c. of the neutral water to
be tested are now run into one cylinder and a similar quantity of
distilled water into the other; 5 c.c. of ammonic nitrate, 10 per
cent, solution, are now added to each cylinder, and then the colour
produced in the cylinder containing the water under examina-
tion is imitated by running into the other cylinder standard
copper solution till the colours in both cylinders are of equal
depth,, the liquid being well stirred after each addition of the
copper solution.
Combination of Acids and Bases. The amount of acids
and bases having been determined, it now becomes necessary to
calculate the salts in the form in which they are generally
believed to exist in water. The salts are usually calculated
on the basis proposed some years ago by Fresenius, the general
rules laid down by him being as follows :
(1) The chlorine is combined with sodium.
(2) Any chlorine afterwards left is combined with calcium,
magnesium, and potassium in respective order.
(3) Potash is next combined with sulphuric acid.
(4) If sodium remains, it is combined with nitric acid (N 2 O 5 ) ;
and if there is still an excess, it is combined with carbon-dioxide.
(5) Lime is first combined with nitric acid, then with sulphuric
acid, and finally with carbon-dioxide. Whilst if chlorine is in
excess of that required to saturate the sodium (these amounts
generally saturate one another), it is combined with calcium.
176 THE BREWER'S ANALYST
(6) Magnesia is combined first with nitric acid (if lime has not
saturated it) then with sulphuric acid, whilst any excess is
combined with carbon-dioxide.
(7) Any excess of lime is always finally combined with carbon-
dioxide ; the reason being that any ordinary water contains C0 2 ,
and any excess of lime must combine with the same to form
carbonates.
The sum of these constituents is checked by the alkalinity of
the water, so that if, by calculation, carbonate of potash or soda
is found to exist, the alkalinity of the water after boiling would
prove the existence of one or the other or both.
The total salts should almost equal the saline residue of the
water when dried at 350 F. (176'6 C.), provided nitrates are
not present.
We may now proceed to combine the acids and bases of the
foregoing analysis, which is that of a water drawn froin a well at
Burton-on-Trent, suitable only for bitter-ale production, and
follow with typical combinations of a water suitable for stout and
porter, and then one suitable for mild-ale production. First,
however, it may be useful if we tabulate the proportions of the
various acids and bases necessary to saturate one another in
order to form salts.
80 parts sulphuric acid combine with
56 parts lime to form sulphate of lime.
40 magnesia to form sulphate of magnesia. -
62 ,, soda to form sulphate of soda.
94 potash to form sulphate of potash.
108 parts nitric acid combine with
56 parts lime to form nitrate of lime.
40 ,, magnesia to form nitrate of magnesia.
62 soda to form nitrate of soda.
44 parts carbonic acid combine with
56 parts lime to form carbonate of lime.
40 ,, magnesia to form carbonate of magnesia.
62 ,, soda to form carbonate of soda.
71 parts chlorine (35'5 x 2) combine with
40 parts calcium to form calcic chloride.
24 ,, magnesia to form magnesic chloride.
46 soda to form sodic chloride.
Now, taking the results of our previously conducted analysis,
we proceed to combine the acids and bases.
METHODS OF ANALYSIS 177
TYPE I.
The sodium being in excess, we take the chlorine and combine
it with sodium :
35'5 parts 01 require 23 parts Na.
90
Therefore 2'37 01 x |f = 1 "53 Na required,
oO *0
and 1-53 Na + 2'37 Cl = 3'90 NaCl.
We now take the potash and combine it with sulphuric acid :
94 parts K 2 require 80 S0 3 .
Therefore 0'86 K 2 x = 073 SO S required,
t?4r
and 0-73 S0 3 + 0'86 K 2 = 1 '59 K 2 S0 4 .
We have now to combine nitric acid with sodium :
108 parts Na 2 combine with 62 parts N 2 5 .
fiO
Therefore 1 '25 N 2 5 x ^ = 071 Na 2 required,
108
and 0-71 Na 2 + 1 -25 N 2 5 = 1 "96 Na(N0 3 ) 2 .
Thus far we have used up 1'53 Na to form NaCl, and 071
Na 2 to form sodic nitrate. But in our analytical figures the
soda 7'25 is expressed as Na 2 ; we have therefore to calculate
the 1-53 Na back to Na 2 :
46 parts Na require 62 parts Na 2 0.
So 1-53 (amount Na used) x _ = 2'06 Na 2 0.
46
Therefore 2-06 Na 2 + 071 Na 2 = 277, the amount of Na 2 used,
and 7'25 Na 2 - 277 - 4-48 Na 2 required.
We have now to combine this 4'48 Na 2 with S0 3 :
62 parts Na 2 require 80 parts S0 3 .
4'48 (Na 2 remaining) x = 578 S0 3 required,
\) 2i
and 578 + 4-48 = 10-26 Na 2 S0 4 .
We have thus used up our soda, 073 S0 3 for K 2 S0 4 and 578
S0 3 for Na 2 S0 4 ( = 6-51 S0 8 ), leaving (52-29-6-51) 4578 SO,.
We have now to combine the S0 3 with lime (CaO) :
80 parts S0 3 require 56 CaO.
12
178 THE BREWER'S ANALYST
e*/
Therefore 45'78 (remaining S0 3 ) x = 32'04 CaO required,
80
and 32-04 CaO + 4578 S0 3 =77'82 CaS0 4 .
This disposes of our S0 3 and leaves us with (36'33- 32-04)-=
4'29 CaO :
56 parts CaO require 44 parts C0 2 .
Therefore 4-29 (remaining CaO) x li = 3'37 C0 2 ,
and 4-29 CaO + 3'37 C0 2 = 7*66 CaC0 3 .
(There are no acids left to combine with the magnesia, which
must therefore exist as carbonate) :
40 parts MgO require 44 parts C0 2 .
Therefore 10-15 (amount of MgO) x = 11 '16 C0 2 ,
40
and 10-15 M 9 0+ 11*16 C0 2 = 21'31
We have already estimated the alkalinity of the water both
before and after boiling, and seen that after boiling the alkalinity
is equal to 31-80 grains per gallon CaC0 3 ; the amount of
carbonates arrived at by calculation may therefore be checked by
this figure.
In our combination results we have 21*31 grains per gallon
carbonate of magnesia :
88 parts MgC0 3 have the same alkalinity as 100 parts CaC0 3 .
So 21-31 x^ = 24-21 asCaC0 3 .
08
Therefore actual CaC0 3 7-66-1- 24'21 = 31-87 grains of alkalinity,
and by our test 31*80 grains.
The composition of the water is therefore as follows :
TYPE I.
Total solids . . . .139*920 grains per gallon.
Saline residue . . . 125-400
Organic and volatile matter . 14*520 ,, ,,
Lime 36*330
Magnesia .... 10-150
Sulphuric acid . . . 52*290 ,,
Chlorine . . . 2 -380
Iron 0-098
Soda 7-250
Potash .... 0-860
Silica . 0-840
METHODS OF ANALYSIS 179
Nitrogen as nitrates and nitrites :
Nitric acid .... 1 -250 grains per gallon.
Nitrous acid . . . Nil.
Organic matter :
Free or saline ammonia . 0'122 parts per million.
Albuminoid ammonia . . 0*062 ,, ,,
Oxygen required to oxidise organic matter :
15 minutes . . . OO25 parts per 100,000
4 hours . . . 0-095 ,,
MOST PROBABLE COMBINATION.
Sodium chloride (NaCl) . . 3'90 grains per gallon.
Potassium sulphate (K 2 S0 4 ) . 1-59 ,,
Sodium nitrate Na(N0 3 ) 2 . . 1'96
Sodium sulphate (Na 2 S0 4 ) . . 10'26
Calcium sulphate (CaS0 4 ) . . 77'82
Calcium carbonate (CaC0 3 ) . 7'66
Magnesium carbonate (MgCO s ) .21-31 ,, ,,
Iron oxide (Fe 2 3 ) . . . 0-09
Silica (Si0 8 ) . . . 0-84
Saline residue . . 125'43
Saline residue found = 125 '40 grains per gallon.
TYPE II.
We will now take a typical analysis of a water suitable for mild
ale production, the analytical figures of which have been deter-
mined as follows :<
Silica . . . .0-26 grains per gallon.
Iron oxide . . . 0*24 ,,
Lime .... 9'79
Magnesia . . . 0'43
Soda .... 0-97
Chlorine . . I'll
Sulphuric acid . . 2'62 ,,
We first take the sodium (Na 2 = 0'97) and calculate it back
to Na :
62 parts Na 2 contain 46 N a.
Therefore 0'97 (amount of Na 2 0) x = 0'71 Na.
62
We combine this with chlorine :
23 parts Na require 35'5 parts Cl.
180 THE BREWER'S ANALYST
So 0-71 (amount of Na)x~-Hl Cl required,
and 0-71 Na+1-11 C1 = 1'82 NaCl.
This disposes of our soda and chlorine (these amounts just
saturating one another). We have neither potash nor nitric acid,
so we proceed to combine sulphuric acid (S0 3 ) with lime (CaO) :
80 parts S0 3 require 56 parts CaO.
Therefore 2 '62 S0 3 x = 1-83 CaO required,
80
and 2-62 SO 8 + 1'83 CaO = 4*45 CaS0 4 .
Our CaO equalled 9 "79, and as we have used 1*83 parts of it to
form CaS0 4 , we have 7 '06 left, which we combine with C0 2 :
56 parts CaO require 44 parts C0 .
Therefore 7'96 (remaining CaO) x i| = 6'25 C0 2 ,.
ob
and 6-25 C0 2 + 7'96 CaO =14*21 CaC0 3 .
We next combine magnesia (0'43) MgO with C0 9 :
40 parts MgO require 44 parts C0 2 .
Therefore 0'43 (amount of MgO) x ^ = 0'47 C0 2 .
and 0-43 MgO + 0'47 C0 2 = 0'90 Mg*C0 3 .
The composition of the water is therefore :
Sodium chloride (NaCl) . . 1*82 grains per gallon.
Calcium sulphate (CaS0 4 ) . . 4'45
Calcium carbonate (CaCO 3 ) .14-21
Magnesium carbonate (MgC0 3 ) . 0"90 ,,
Iron oxide (Fe 2 3 ) . . " . 0*24
Silica (SiO 8 ) . . . 0'26
TYPE III.
We finally take a typical analysis of a water suitable for stout
and porter production, the analytical figures of which have been
determined as follows :
Silica .... 0-22 grains per gallon.
Iron .... 0-24
Lime . . . 13-13
Magnesia . . . 1"91
Soda .... 18-62
Chlorine . . . 23'81
Sulphuric acid . . 3 '6 7
METHODS OF ANALYSIS 181
We first take the soda, which is expressed in our analysis as
Na 2 0, and calculate it back to Na]:
62 parts Na 2 contain 46 parts Na.
18-62 (amount of Na 2 0) x 1? = 13-81 Na.
o 2i
We now combine this with chlorine :
23 parts Na require 35-5 Cl.
OK.K
Therefore 13 "81 Na x - t - = 21 '31 Cl required,
aw
and 21-31 Cl + 13'81 Na = 35*12 NaCL
We have thus used up our sodium and have (23*81 Cl - 21 '31 Cl)
2-50 Cl left.
We have now to combine this Cl with calcium (Ca) :
35-5 parts Cl x 2 = 71 parts Cl, which combine with
40 parts Ca to form CaCl.
Therefore 2-50 (Cl remaining) x ^ = 1 -40 Ca required,
and 1-40 Ca + 2'50 Cl = 3'90 CaCL
We now take our S0 3 (3'67) and combine it with lime (CaO) :
80 parts SO 3 require 56 parts CaO.
Therefore 3'67 (S0 3 ) x ~ = 2'56 CaO required,
and 2-56 CaO + 3'67 S0 3 = 6'23 CaSo 4 .
Of our original lime 13'13 we have bound 1'40 with chlorine
to form CaCl and 2 56 with S0 3 to form CaS0 4 : 1'40 + 2'56 = 3'96
and 13-13-3 96 = 9-17.
Lime remaining :
56 parts CaO require 44 parts C0 >2 .
Therefore 9-17 (lime remaining) x -=7'20 C0. 2 ,
and 9-17 (lime) + 7'20 C0 2 =16'37 CaC0 3 .
We now finish with the magnesia (1'91 MgO) :
40 parts MgO require 44 parts CO 2 .
Therefore 1'91 (amount of MgO) x - 2-10 C0 2 ,
and 1-91 MgO + 2'10 C0 2 = 4'01 MgC0 3 .
182 THE BREWER'S ANALYST
The composition of the water is therefore :
Sodium chloride (NaCl) . . 35'12 grains per gallon.
Calcium chloride (CaCl 2 ) . 3 '90
Calcium sulphate (CaS0 4 ) . . 6'23
Calcium carbonate (CaC0 3 ) . 16*37
Magnesium carbonate (MgC0 3 ) . 4*01 ,, ,,
Iron oxide (Fe 2 3 ) . . . 0'24
Silica (SiOj) . . . . 0-22
The foregoing calculations can all naturally be shortened by
cancelling and the use of factors, but are given in detail so as to
be explicit to the student.
BISULPHITE OF LIME ANALYSIS.
The following are the determinations to be made :
1. Specific gravity.
2. Total sulphurous acid (free and combined).
3. Sulphuric acid.
4. Lime.
5. Magnesia.
6. Chlorine.
7. Iron.
8. Hyposulphites.
The bisulphite should be drawn from the cask through a
freshly bored peg-hole into a clean dry stoppered bottle, the
stopper being tightly fitted and the contents well shaken before
use. The bottle should be immersed in cold water or the con-
tents otherwise brought to 60F. (15-5 C.) before commencing
the analysis, and owing to the rapidity with which the sulphite
oxidises when exposed to the air and the volatilisation of S0 2 , it
is essential to perform each experiment as quickly as possible.
1. Specific Gravity. This is determined in the ordinary
manner by the aid of the specific-gravity bottle (fig. 36,
p. 33).
2. Total SulphUPOUS Acid. Gravimetric Method. The total
sulphurous acid may be determined either gravimetrically or volu-
metrically. In the former case the sulphurous acid, both free and
combined, is first oxidised into sulphuric acid and then determined
by the aid of baric chloride, the amount of sulphurous acid being
calculated from the weight of the precipitated baric sulphate.
We have first, however, to determine the weight of baric sulphate
METHODS OF ANALYSIS 183
which may be due to any sulphuric acid existing as such in the
bisulphite owing to oxidation, and deduct this from the total
weight of baric sulphate, calculating the difference into sulphurous
acid. We therefore proceed as follows :
Add to a beaker about 120 c.c. distilled water and about
10 c.c. bromine and stir well. Now measure 20 c.c. of the
bisulphite in a 200 c.c. flask and make to mark with distilled
water =10 per cent, solution. Run 10 c.c. of this 10 percent,
solution into the previously prepared bromine water = 1 c.c. of
bisulphite. The solution should now be distinctly brown ; if it is
not, add a few more drops of bromine and stir well. Now add
2 or 3 c.c. hydrochloric acid and boil the solution over a Bunsen
name until the whole of the free bromine is volatilised and the
solution is free from colour. The sulphurous acid has now been
oxidised into sulphuric acid, the bromine having decomposed
the elements of water and combined with the hydrogen to form
hydrobromic acid, whilst the sulphurous acid has seized the
liberated oxygen.
The sulphuric acid is now determined in the solution in exactly
the same manner as in water analysis, and the sulphurous acid
calculated after deducting the BaS0 4 due to sulphuric acid natur-
ally present in the sample.
Example. To the colourless boiled solution a few drops of baric
chloride are added, the solution further boiled for a minute or two
and then set aside in a warm place until the baric sulphate has
settled and the supernatant liquid is perfectly clear. The solu-
tion is then filtered, the filter paper repeatedly washed with hot
distilled water, dried, folded, and ignited in a tared crucible.
The crucible is then cooled under the desiccator and weighed.
The weight is found, say, to be :
Weight of crucible + BaS0 4 . . 6 '801 grams.
Weight of crucible . . . 6'540
BaS0 4 . . 0-261
It is found, however, that 1 c.c. of the bisulphite contains '007
BaS0 4 due to sulphates naturally present, so 0'261 - 0'007 = 0*254
BaSO 4 from sulphurous acid (S0 2 ) in 1 c.c.
As shown under Water Analysis, the atomic weight of baric
sulphate is 233, and that of sulphurous anhydride 64, so that
every 233 parts of BaS0 4 correspond to 64 parts S0 2 , or 1 gram
to 0-2746 = 0-06974 gram SO 2 in 1 c.c. bisulphite or 6'974 per
100 c.c.
184 THE BREWER'S ANALYST
Let us now confirm this gravimetric method by the volumetric
process.
This depends upon the beautiful and sensitive iodine reaction
already fully described under Sulphurous Acid (p. 149).
Measure 20 c.c. of the bisulphite into a 200 c.c. flask and
dilute to mark with recently prepared distilled water. Now
take 10 c.c. of this solution in a porcelain dish, add a few drops
of gelatinised starch solution (footnote, p. 172), and titrate with
N
-- iodine until a blue colour makes its appearance and becomes
permanent on standing.
N
Suppose the amount of iodine used = 2J c.c. Then, as each
c.c. of iodine corresponds to 0*0032 sulphurous acid 21 x 0-0032 =
0-0672 S0 2 in 10 c.c. dilute bisulphite ( = 1 c.c. of bisulphite),
and 0-0672 x 100 = 6'72 S0 2 per 100 c.c. as against 6 '97 per 100
c.c. found gravimetrically. If only the volumetric method is em-
ployed, then it becomes necessary to confirm the result by
N"
titration with iodine, by using an excess of the latter and
N
performing a second titration by the use of ^ thiosulphate as
exemplified under Sulphurous Acid, p. 149.
3. Sulphuric Acid. Add about 10 c.c. concentrated hydro-
chloric acid and about 100 c.c. distilled water to a small boiling
flask and boil for a few minutes to expel the air from the flask
and free oxygen from the water. Now add 50 c.c. of the bi-
sulphite and boil for about 15 minutes, or until the evolved
steam no longer smells of sulphurous acid. Transfer the contents
of the flask to a beaker, dilute slightly with distilled water, add
about 10 c.c. baric chloride solution, and set aside in a warm
place until the baric sulphate has precipitated and the super-
natant liquid is clear. Now filter, wash with hot distilled water,
dry, ignite, cool, and weigh as baric sulphate (BaS0 4 ).
Example :
Weight of crucible + ash . . . 6*797 grams.
Weight of crucible .... 6'500
BaS0 4 . . . 0-297
The atomic weight of BaS0 4 is 233, and that of sulphuric
anhydride (SO,) 80. 233 parts of BaS0 4 therefore correspond
Qf\
to 80 parts of sulphuric anhydride, =-343, so that
METHODS OF ANALYSIS 185
0-297 x -343 = -1018 S0 3 in 50 c.c. bisulphite x2 = 0'203 per
100 c.c.
4. Lime. Make a 10 per cent, solution of the bisulphite by
taking 20 c.c. and making- up to 200 c.c. with distilled water.
Measure 20 c.c. of this 10 per cent, solution ( = 2 c.c. bisulphite)
into a beaker, add about 150 c.c. distilled water and about 10 c.c.
animonic oxalate, about the same quantity of ammonic chloride,
and about the same quantity of ammonic hydrate. Gently warm
the liquid and allow to remain at rest for about 3 hours and
then filter. (The filtrate is required for the following magnesia
estimation.) Wash the precipitate with hot distilled water, dry,
ignite, cool, recarbonate, heat gently, cool under desiccator, and
weigh as calcic carbonate (CaC0 3 ).
Example :
Weight of crucible + ash . . . 6'588 grams.
Weight of crucible .... 6 '500
0-088
0-088 x -56 = 0-049 CaO in 2 c.c. bisulphite and x 50-2-450
lime (CaO) per 100 c.c.
5. Magnesia. To the filtrate from the previously described
lime estimation add about 10 c.c. ammonic or sodic phosphate
and about a like amount of ammonic hydrate ; stir well and set
aside for 6 hours. Now filter, wash the precipitate with dilute
ammonia, dry, ignite, cool, and weigh as pyrophosphate of
magnesia 2(MgO)P 2 5 .
Example :
Weight of crucible + ash . . . 6 '5 11 grams.
Weight of crucible . . . 6-503
008
The atomic weight of 2(MgO)P 2 5 is 222, and that of 2MgO 80,
so that 222 parts of pyrophosphate correspond to 80 parts of
80
magnesia, ^-='36. So that O'OOS x -36 = -00288 magnesia in
222
2 c.c. bisulphite, which x 50 = 0' 1 50 per 100 c.c.
6. ChlOPine. Take 25 c.c. of the bisulphite in a platinum or
porcelain dish, evaporate to dryness over the water bath, moisten
the residue with a little distilled water and again evaporate to
dryness, repeating the moistening with distilled water and
evaporation to dryness three times. Now dissolve the residue
with hot distilled water and transfer to a filter paper and filter
186 THE BKEWER'S ANALYST
collecting the filtrate in a clean porcelain dish. Wash the
precipitate with hot distilled water and collect the filtrate in the
same porcelain dish. Now add to the filtrate one or two drops
of potassic chromate and titrate with a standard solution of
argentic nitrate (p. 137) as in Water Analysis, p. 160.
Example. 25 c.c. of the bisulphite took 1'7 c.c. of argentic
nitrate, so that as each c.c. of the silver solution corresponds to
O'OOl gram of chlorine, I '7 x '001 = "0017 in 25 c.c. x 4 = '0068
gram Cl per 100 c.c.
To bring this to terms of common salt (sodic chloride) the
atomic weight of chlorine (Cl) is 35 '5, and that of sodic chloride
(NaCl) 58-5.
Every 35*5 parts of chlorine therefore correspond to 58 '5 parts
58'5
of sodic chloride = 1'645, so we multiply by the factor 1'645
oo'D
or, roughly, by l'65-O'Oll NaCl per 100 c.c.
7. Iron. Measure 20 c.c. of the bisulphite into a small
beaker, add about 50 c.c. distilled water and a few drops hydro-
chloric and nitric acids and boil until the evolved steam no
longer smells of nitrous or sulphurous fumes. Now cool, transfer
to a 100 c.c. flask and dilute to mark ( = 20 per cent, solution).
Of this solution take 50 c.c. in a Nessler tube, add a drop or two
of potassic ferrocyanide, and stand for a minute or two, when,
if iron is present, a blue colour will have developed varying in
intensity with the amount of iron. Now take a second Nessler
tube, add 50 c.c. distilled water, a drop or two of potassic ferro-
cyanide, and run in from a burette a standard solution of iron
(p. 137), until the colour, which develops on standing for a few
minutes after each addition of iron, exactly matches in intensity
that of the bisulphite solution.
Suppose the quantity of iron solution used equals 30 c.c. ; then,
as each c.c. of iron solution is equivalent to O'l milligram of iron
30 x O'l = '30 milligram of iron, and "30 x 5 = 1*50 milligram iron
in the 100 c.c. of 20 per cent, bisulphite solution. Therefore
1-50 x 5 = 7'50 milligrams per 100 c.c. of the bisulphite, or '0075
gram.
It is usual, however, as in water analysis, to express the iron
as ferric oxide (Fe 2 3 ), so that as 160 parts of Fe 2 3 correspond to
112
112 parts of iron . = -7. We multiply '0075 x '7 and obtain
iron as '0052 (Fe 2 3 ) per 100 c.c.
8. Hyposulphites. These bodies, if present, render the
bisulphite utterly unfit for use. It is therefore only necessary
METHODS OF ANALYSIS 187
to detect their presence, no estimation being necessary; and, if
found to exist, the bisulphite should be at once condemned as unfit
for use.
Their detection is a simple matter ; all that is needed is to add
to the bisulphite concentrated hydrochloric or any strong mineral
acid and raise to the boil, when, if hyposulphites exist, a yellow
precipitate of sulphur is thrown down. The precipitate should
not be confused with one of a white colour sometimes obtained
by this treatment. .
Combinations. We have now to combine acids and bases,
our determinations being :
Per cent.
Total sulphurous acid . . . 6'974
,, sulphuric acid .... -203
lime 2-450
,, magnesia '150
chlorine '006
,, iron -005
We first take the '203 sulphuric anhydride (S0 8 ) and saturate
it with lime equivalent :
80 parts S0 3 combine with 56 parts CaO.
Therefore ' 20 |j * 56 = '142 CaO.
(142 + -203) = '345 per cent. CaS0 4 (calcic sulphate).
142 parts of lime having thus been disposed of, the remainder
(2'450 "142) = 2*308, so that this now requires to be combined
with sulphurous acid (S0 2 ), the atomic weight of which is 64.
Therefore ^ u g x ^ . 2'602 S0 2 ,
_x 64
56
and 2-602 + 2-308 = 4-91 per cent, calcic sulphite (CaSO 3 ).
Having thus completely saturated the lime, we have now to
deal with the magnesia and combine this also with sulphurous
acid. The atomic weight of MgO is 40, so that - 5 * 64 = -24
S0 2 , combining with '15 MgO to form '39 per cent, magnesic
sulphite (MgS0 3 ). The total amount of sulphurous acid is 6 -9 74
per cent., and the amount required to saturate the lime (2*60) and
magnesia ('24) added together = 2 '84, which deducted from the
total = 4'13 per cent, free sulphurous acid. The full analysis
is therefore as follows :
188 THE BREWER'S ANALYST
Analysis of Bisulphite of Lime expressed on 100 parts by volume.
Specific gravity . . . 1069-0
Total sulphurous acid . . 6 '97 per cent.
Free sulphurous acid . . 4 '13 ,,
Combined sulphurous acid . 2 '84 ,,
Calcic sulphate . . . 0-34 ,,
Calcic sulphite . . . 4'91
Magnesic sulphite . . 0*39 ,,
Sodic chloride . . O'Oll
Ferric oxide . . . 0*005
Hyposulphites . . . Nil.
The results of analysis are frequently required to be expressed
on 100 parts by weight instead of on 100 parts by volume as
above. In such instances, taking the present analysis as an
example, the results would work out thus :
The specific gravity of the bisulphite was found to be 1069 ;
the actual weight of 100 c.c. is therefore 106-9 grams, or 100
parts by volume equal 106 '9 parts by weight; therefore each
100
figure of the analysis multiplied by - expresses the results
106*9
in percentage on the latter.
Example :
Total SO 2 = 6*97 in 100 c.c.
Therefore ^ X - 100 == 6-52 per cent, total S0 2 by weight.
Free S0 2 = 4*13 in 100 c.c.,
= 3-86, and so on with each item.
106*9
The results therefore stand :
Analysis of Bisulphite of Lime expressed on WO parts by weight.
100 parts weight . . . 106*9 grams.
Total sulphurous acid . . 6*52 ,,
Free sulphurous acid . . ' 3*86
Combined sulphurous acid . 2*65 ,,
Calcic sulphate . . . 0*30
Calcic sulphite . . . 4*59 ,,
Magnesic sulphite . . 0*36 ,,
Sodic chloride . . . 0*11
Ferric oxide .... 0'004
Hyposulphites . . . Nil.
METHODS OF ANALYSIS 189
SOLID SULPHITES.
Calcic Sulphite. Sodic Sulphite. Potassic Sulphite.
CALCIC SULPHITE.
The determinations to be made are :
Lime.
Sulphurous acid.
Sulphuric acid.
Iron.
The same general methods are adopted as those given for
bisulphite of lime, half a gram of the sulphite being dissolved in
distilled water and made up to 100 c.c. at 60 F. (15'5 C.) and
the analysis proceeded with as described.
In some instances it will be found that there is a proportion
of the lime CaO or CaCO 3 uncombined with acid, the presence
of which is indicated when the acids fail to satisfy the base ; and,
if desired, a determination of the alkalinity or carbonic acid may
be made, as described under Water Analysis, to check such result.
Samples of soluble or precipitated sulphite contain an equivalent
of water of crystallisation, the sulphite existing as CaS0 3 + H 2 ;
with such, the analytical results will of course not add up to 100
parts, even when the moisture has been determined, because the
water of crystallisation is not expelled, except at higher tempera-
tures than can be employed without decomposing the salt.
SODIC AND POTAHSIC SULPHITE.
With these it is only necessary to determine the sulphurous
and sulphuric acids and ferric oxide. The bases are not usually
determined, but if required they can be done as described under
Water Analysis.
MALT ANALYSIS.
The following are the determinations to be made :
1. Extraneous matters.
2. Defective corns.
3. Weight per bushel.
4. Steely corns and modification.
5. Specific gravity of 10 per cent, solution.
6. Extract per quarter.
7. Dry extract per cent.
190 THE BREWER'S ANALYST
8. Saccharification period.
9. Specific rotatory power of mash wort.
10. Acidity.
11. Moisture.
12. Matters soluble in cold water
13. Ready -formed soluble carbohydrates.
14. Colour of wort.
15. Mineral matter or ash.
16. Total proteids or albuminoids.
17. Soluble proteids or albuminoids.
18. Insoluble proteids or albuminoids.
19. Diastatic power.
Sampling*. Care should be exercised in obtaining an average
sample of the malt. With malt heaped up on the kiln or in store,
a little should be taken from different parts of the bulk. With
malt delivered in sacks, a sample from the top, middle, and
bottom of several sacks should be selected. The well-known
FIG. 65.
corn sampler (fig. 65) may be conveniently employed for this
purpose. The various portions selected in this manner from 3,ny
one particular class of malt should then be well mixed together
and about 200 grams taken and screened.
1. ExtFaneOUS MattePS. A very simple and efficient screen
for this purpose is the " Boby," which consists of a series of iron
rods fixed together in the form of a frame which, enclosed in a
box, may be given a fast or slow reciprocatory motion by hand
at the manipulator's desire, or the well-known miniature screen
shown in fig. 66. The refuse such as rootlets, tail corn, and other
bodies falls through the mesh, from whence it may be collected
and weighed. Thus, if we take a definite quantity of malt, screen
it, and weigh the extraneous bodies, we naturally arrive at the
quantity originally present in the sample. In one instance 200
grams were taken and screened; the screenings, together with
seeds, stones, and other rubbish picked from the malt, weighed
2-4 grams = 1 '2 per cent, extraneous matters.
2. Defective Corns. These include corns which are crushed,
mouldy, half corns or extremely minute in size. Five hundred
METHODS OF ANALYSIS 191
corns are promiscuously separated from the sample and the per-
centage ascertained.
3. Weight pep Bushel. It is necessary to remember that
malt just off the kiln is warm, and that when in this condition it
is impossible to obtain its correct weight. It is wise in fact not
to attempt the weighing of any malt until it has been off the kiln
for at least 24 hours. The weight is ascertained by the instru-
ment known as the " chondrometer " (fig. 67), which consists of a
balance provided with a small measure to hold about a half-pint.
The measure is filled with an average screened sample of the
bulk from which the impurities such as stones, etc., have been
removed ; the surface is levelled with the " strike " and the weight
ascertained. The weights bear the same proportion to the measure
FIG. 66. FIG. 67.
as pounds do to the bushel, so the weight in pounds per bushel
is read off directly. 1
4. Steely Corns and Modification. Imperfectly vegetated
or kiln-dried malts contain varying proportions of steely corns
which are resistant to the bite and usually roughly detected in
this manner. If selected and cut in two, it will be found that
the starch has a peculiar cast and a vitreous or glassy appearance.
It is advisable to estimate the steely corns, and this is most
readily performed by means of the well-known "farinator"
(fig. 68), which cuts through 50 or 100 corns with one stroke of
the knife. Further, it has been found that light will pass through
glassy but not through mealy corns. From this fact the instru-
ment designated the " diapharioscope " (fig. 69) has been con-
structed It consists of a box made of sheet metal, in the
interior of which is placed a petroleum, gas, or electric lamp. The
roof of the apparatus is provided with a number of slits, into each
1 The results obtained must be regarded more as comparative values than
reliable determinations of the actual bushel weight of the corn.
192 THE BREWER'S ANALYST
of which a corn of malt is placed. The quality of the malt is
then judged from the relative transparency of the corns.
In examining malt by either the farinator or diaphanoscope, it
is usual to operate on 500 corns. These are divided into three
classes floury, vitreous, and semi-vitreous ; the numbers thus
obtained, divided by five, giving the respective percentages of the
different classes.
The old-fashioned " sinker " test was formerly much in vogue,
and was considered capable of testing the percentage of semi-
grown or dead corns in a sample of malt. It originated from
a paragraph in Edward Lisle's work entitled Observations in
FIG. 68. FIG. 69.
Husbandry, 1757, p. 205, where he states: "My maltster sent
me malt which my butler was not pleased with. He said there
were many grains in every handful of it which were not malted
at all, and many grains that were but half-malted, of which I
might be satisfied if I made trial in water ; for the corns which
were not malted at all would sink to the bottom, and the half-
malted grains would swim on end like a fishing quill. I called for
a basin of water to make the experiment and found it to be true."
The test is carried out by counting three or four separate
hundred corns, or measuring off 300 or 400 corns in a small
thimble or measure, 1 throwing the corns into a tumbler of water,
well stirring for about half a minute, and counting those that
sink and those that float perpendicularly.
The principle of the test depends upon the fact that corns
1 This method is much quicker than counting, and the error in the number
taken does not amount to more than a few corns, being inappreciable in
the result.
METHODS OF ANALYSIS 193
which contain their starch, or a portion of it, in an unmodified,
steely, or vitreous state, have a specific gravity greater than water,
and sink when immersed. There are of course gradations in this
difference of specific gravity, and many corns will be found to float
in a perpendicular position which, on examination, may be found
to have steely tips, but in which the balance of specific gravity
between the friable portion of the corn and its steely part is so
close as to prevent its subsidence. Also a shrivelled corn in which
the plumule may have grown completely out, and yet not com-
pleted the whole of its modification, may occasionally be found
floating. When this occurs it is in the case of a thin corn in
which the growth of the plumule has apparently been too great
to be sustained by the ordinary available food supply. A large
portion of the cell walls, being in a steely state, has remained
unmodified, and the embryo has used up the reserve starch along
the dorsal side of the grain, depleting the endosperm cells.
During the kilning process the corn becomes unduly shrivelled,
and sometimes leaves sufficient air-space beneath the husk to turn
the scale in favour of its floating.
Meacham, some two or three years ago, suggested the use of a
5 per cent, solution of methylated spirit in place of ordinary water ;
the decrease in specific gravity of the water thus produced bringing
down those corns which, by reason of their being very slightly
steely at the tips, otherwise float perpendicularly in ordinary water.
A further test is that of immersing the malt in toluol. 1 The
specific gravity of malt immersed in this solution varies from 0'95
to I'l; and, generally speaking, malts with specific gravity less
than 1 '0 are well modified, whilst those showing a specific gravity
above this are not considered to be well modified.
On the whole, it may be stated that the sinker test with water
or aqueous methylated spirit, and the method of judging modifica-
tion from the specific gravity found by the aid of toluol, are
decidedly unsatisfactory. The percentage of sinking corns varies
so much from day to day, and is dependent upon so many condi-
tions, that it is dangerous to condemn a sample of malt which
may be very good from a chemical point of view and bad if done
1 Toluol, or, as it is better known, toluene, is a hydrocarbon of the aromatic
series, with a boiling point of 231 '8 F. (111 C.) and a specific gravity 882 '4
(water = 1000). It is used for taking the specific gravity of malt in precisely
the same way as the specific gravity of a solid is usually taken with water, a
method to be found in any elementary text-book on physios. It is necessary
to use toluene instead of water when dealing with malt, because of the solvent
action of the latter on certain constituents of the malt. Toluene, it is stated,
has no solvent action on the malt.
13
194
THE BE EWER'S ANALYST
by either of these methods. Tt is decidedly more advantageous
and reliable to count or measure out several separate hundred
corns and examine the degree of growth of the acrospire of each,
so arriving at fair conclusions as to irregularity of growth or
otherwise of the sample ; whilst for steely, vitreous, or dead corns
examination should be made by means of a penknife, separating
out the dead or idle corns, vitreous corns, steely-backs, and steely-
tips, classifying them in percentages.
Examination by means of the diaphanoscope or farinator is,
however, reliable, so that we may resort to these methods of
procedure and discard the sinker or specific-gravity tests as
obsolete and next to useless.
The acrospire in the corns of good malt should be well and
evenly grown, the average length being between two-thirds and
three-quarters up the back. There should be few corns in which
it either pierces the end or fails to extend to more than half up.
As the vitality of barley is the chief characteristic when judging
its quality, so the growth of malt is also the main factor in con-
sidering its positive and comparative value.
The word growth has ;i wider significance than vitality ; for, al-
though no barley can possibly possess too much vitality, malt which
is grown too much is of greatly reduced value. Any corn which
remains unvegetated is not malt, but barley, and the paramount
importance of the growth of the acrospire is consequently obvious.
To detect regularity in growth, a number of corns are taken
promiscuously from a sample, say several lots of 200 each, and
the number of corns which have grown to the various different
lengths, or grown out, are determined by inspection ; and the
different groups of figures so obtained, divided by two, give the
percentages. The following typical illustrations, giving per-
centages of growth, show the value of uniformity in samples from
careful examination.
PERCENTAGE or GROWTH.
Good Malt.
Medium Malt.
Bad Malt.
Acrospire grown out .
,, I up back .
;: :: ! ;: :
, , started
1
9 4
64 80
26 9
1 3
1
3
7 4
64 79
14 11
6
3 2
12 26
19 21
42 28
17 9
1
2
Dead corns ....
2
3 4
8 15
100 100
100 100
100 100
METHODS OF ANALYSIS 195
Grinding". Much controversy has taken place within recent
years as to the degree of fineness to which the malt should be
ground. Some prefer to grind to powder, others only to a coarse
state such as is usual when grinding on a practical scale in the
brewery. It naturally follows that two analysts, one grinding
the malt to powder, the other only grinding so that the grist
resembles the degree of fineness which is usual in practical opera-
tions, obtain very dilt'erent results. In fact a difference of 3 or
4 Ibs. per quarter results in the amount of extract obtained by
grinding in both ways.
The old method of grinding, and at present largely practised,
is by the use of the coffee-mill ; and naturally, as the fluted
cone is fixed or screwed up in these mills to different degrees,
hardly two mills grind to the same degree. In any case, how-
ever, where such mills are employed, they should be arranged so
that the interior may be cleaned before grinding.
In view of the fact that different analysts obtain different
results by reason of the variance in the degree of fineness in
grinding, it became obvious that a fixed standard was desirable,
and some years ago it was agreed by many analysts to grind the
malt to the finest powder. By this method, however, the extract
obtained is far and away greater than can be obtained from the
malt in practice ; and, more particularly, steely corns which give
little or no extract in the ordinary manner are, upon being
reduced to powder, rendered amenable to the influences of heat
and diastase.
In order to avoid these drawbacks, that is to say, enable
the operator to grind to any desired degree of fineness and
express the degree so that it may be known under what
standard in this direction his analysis is conducted, Messrs
Seek Bros., Ltd., of Dresden, Germany, some few years ago
introduced their now well-known "Seek mill" for use either
in the brewery or for laboratory purposes, the latter being shown
in fig. 70 (p. 196).
In this mill the malt is crushed between two steel rollers as in
actual practice. One of them is mounted in stationary bearings,
whilst the other is capable of adjustment by means of an eccentric
and lever, the adjustment being indicated on a scale graduated
from to 50.
The following figures represent the results obtained with the
Seek mill by grinding to varying degrees, and they illustrate
not only the wide difference in extract obtainable from one and
the same malt, but also the fact already referred to, that in the
196
THE BREWER'S ANALYST
case of a steely malt these differences will be much greater than
in that of a tender sample.
EXTRACTS PER 336 LBS.
Ground
to flour.
Seek 10.
Seek 20.
Seek 30.
Seek 40.
Seek 50.
English malt tender
97-6 96-9
96-5
96-0
95-6
94-1
English malt fairly
98'4
97-6
967
96'2
951 94-0
tender
English malt very
93-9
92-0
91-5
89-8
87'5 85-0
steely
Californian malt . 91 "6
90-6
89-6
89-0
86-6
85-2
For laboratory purposes the mill is, as a rule, set at 25, this
being the standard adopted on the Continent.
There is this, however, to be said with regard to the grinding
of malt, that so far as
the consulting analyst is
concerned, with the Seek
mill he should state in his
analysis the degree he set
the mill to before grinding.
Whilst if a coffee-mill is
employed, he should grind
to powder, state this in
his analysis, and by no
means omit reference to
' the percentage of steely
corns, since these, as
before stated, with fine
grinding give extract.
With the analyst on
the brewery premises, if
FIG. 70. a Seek mill is employed
it should always be set at
the same degree ; whilst in the absence of such mill a coffee-mill
may be employed, since by its use the grain will always be ground
to the same degree and the evaluation of his malts will always
be judged from this and his comparisons uniformly drawn.
5. Specific gravity of 10 per cent, solution.
6. Extract per quarter.
7. Dry extract per cent.
METHODS OF ANALYSIS 19?
The method which has been most widely adopted in this
country for ascertaining the iirst and second of these estimations
is that proposed by Heron l in 1888, and modified somewhat
later, 2 which essentially consists as follows :
Measure 400 c.c. of distilled water and run the same into a
copper or enamelled beaker of about 1 litre capacity. Place the
beaker containing a thermometer in a water bath in which the
water is maintained by a thermostat (fig. 32, p. 27) at a constant
temperature of 150 F. (65*5 C.). While the water is heating,
weigh 50 grams of the screened malt in a small tared beaker ; add
three or four extra corns, grind in a coffee or Seek mill, transfer
the grist to the same beaker and again weigh, withdrawing grist,
if necessary, until exactly 50 grams are obtained.
When the 400 c.c. of water registers a temperature of 150 F.
(65*5 C.), add the 50 grams of grist and stir well with the
thermometer.
The miniature mash so made will shortly register an initial
temperature of 150 F. (65'5 C.), and should be maintained at this
temperature for 1 hour, which is more than ample time for
complete saccharification to be /effected.
8. Saeeharification Period. In order to record the time in
which complete saccharification has taken place, a drop of the
wort should be removed from the mash by the withdrawal of the
thermometer. The drop should be allowed to fall from the
thermometer upon a white surface such as a white tile then
cooled, and a single drop of iodine solution added. The absence
of a blue colour proves the absence of soluble starch, and hence
saccharification, so far as it is capable of being accomplished by
the infusion process, is complete, the modified starch of the malt
having been transformed. The test for starch should be carried
out 10 minutes after the mash has been made, and every 5
minutes afterwards, so long as a blue colour appears. It will be
found, however, that the saccharification period of malts is usually
from 20 to 30 minutes from the time the mash is made, so there
is no perceptible loss of extract by the withdrawal from the mash
of 4 or 5 drops.
Let us assume that the mash shows no blue colour with iodine
after 25 minutes' infusion : the saccharification period is therefore
25 minutes. At the end of 1 hour's infusion the beaker contain-
ing the mash is removed from the water bath and the temperature
of the contents raised to 160 F. (71 C.). The mash is then
1 Jnl. Soc. Chan. Ind. , vii. 259.
3 Jnl. Fed. Inst. Brewing, 1895, i. 116, and 1902, viii. 666.
198 THE BREWER'S ANALYST
transferred to a graduated glass jar through a copper or glass
funnel, the beaker carefully washed out with distilled water, and
the washings added to the graduated jar. The jar is then
immersed in cold water so that the contents may cool, and the
volume is finally made up to 515 c.c. at 60 F. (15'5 C.) with
distilled water. The stopper is then inserted in the neck of the
jar and the contents vigorously shaken and then thrown upon a
filter and the filtered wort collected in a clean dry beaker. Every
100 c.c. of the filtrate will now contain the extract derived from
10 grams of malt. The specific gravity of the wort is now taken
at 60 F. (15*5 C.) by means of the specific-gravity bottle (p. 33,
fig. 36), and from this the extract is obtained by subtracting 1000
(weight of water) and multiplying the remainder by 3*36. This
factor is arrived at as follows :
W = weight in Ib. of 1 quarter of malt.
V = volume of wort in c.c.
S = specific gravity of wort, less 1000.
p = quantity of malt in grams employed for the
determination.
E = extract in Ibs. per quarter.
F wvs
The E ~ 16665
when Y = 100 and p = 10.
T , p, W100S WS
E= 1000-10 = TOO ;
and if we assume that all malts weigh 336 Ibs. per quarter, then
E = S 3-36.
Example :
1029'! 1 is found to be the specific gravity.
Then 29'11 x 3'36 = 97'80 Ibs. extract per quarter.
and 29-11 4-3-86 ! = 7-541 dry solids per 100 c.c.
7-541 x 10 = 75-41 Ibs. dry extract per cent.
It will be noticed in the above experiment that, having taken 50
grams of grist and mashed with 400 c.c. of water, the bulk is
finally made up to 515 c.c. Heron's contention is that the
average volume of the grains from 50 grams of malt is 15 c.c.
On this assumption, therefore, his wort would measure 500
c.c., and by the use of the factor 3'36 he obtains in the most
direct manner the extract per 336 Ibs.
In January 1891 a paper was published by Briant in the
Analyst in which he takes exception to Heron's method for the
1 Solution factor, p. 57.
METHODS OF ANALYSIS 199
determination of the extract of malt. Brian t says : " This method
is not, in my opinion, entirely satisfactory ; Heron, it will be
remembered, makes up to a constant bulk of 515 c.c., yet there is
a very great variation in the amount of husk contained in malt
samples. This is abundantly evident to anyone who is accustomed
to the analysis of malts, and the amount of husk in a thin, foreign
barley malt is manifestly very much larger than that in a thin-
skinned, plump, bold English or Scotch barley malt. There is
thus an error introduced due to this difference for which Heron
has not made allowance."
Then he goes on to describe a method proposed by him which,
he says, eliminates the error arising from the difference in amount
of husk, and gives the true extract value of the malt sample.
Frew, in his paper on some notes on the analysis of malts, 1 a
paper which, under a plea for simplicity and uniformity, appears to
have been written with the set purpose of condemning in no measured
terms the analytical English methods and extolling to the skies
the German methods, says : " Heron's method of making up to a
final volume of 515 c.c., based as it is upon an assumption, would
be quite good enough if the volumes of the grains from all malts
were equal, but this we know is not the case. The extract
obtained by the use of this method from a heavy, thin-skinned,
well-modified malt cannot be compared with that from a husky
eastern malt of a somewhat steely character."
In answer to these criticisms, Heron 2 points out to what extent
the difference in volume produced by the grains from different
malts influence the extract. He says : "I have made extensive
analyses of a good many malts and of various qualities in my time,
and the smallest volume occupied by the grains, I found, was equal
to 13 c.c., whilst the largest never exceeded 17 c.c.
"Now, suppose we had a malt the grains of which exactly
occupied a volume equal to 15 c.c., and which gave an extract of,
say, 90 Ibs. ; and another malt giving likewise an extract of 90 Ibs.,
but whose grains occupied a volume equal to 17 c.c., but that the
total volume of the wort was made up to 515 c.c. what will be
the error introduced 1 ? Why, the enormous amount of-fO'34
Ib. On the other hand, with a malt whose grains occupy a
volume of only 13 c.c. and giving also, say, an extract of 90 Ibs.,
the error will be - 0'34 Ib. But, as a matter of fact, such malts
are very exceptional, and, in the great majority of cases, the error
does not amount to more than + or - O'l to 0'15, and I think
1 Jnl. Fed. Inst. Brewing, 8, 341.
2 Ibid.. No. 6, 1902,668.
200 THE BREWER'S ANALYST
such an error as this in the determination of the extract of malt
may very well be neglected."
From this controversy the reader may take it for granted that
Heron's method is to all intents and purposes as near perfection
as anything can be, and is adopted in preference to others which
introduce errors as great and in most cases greater than the
infinitesimal amounts shown by him from an extensive number of
experiments with different varieties and qualities of malt.
Determination of the "Full Theoretical" Extract.
The method of Heron's, already described, is employed to
determine the extract of malts when mashed under conditions
approximating to those in the brewery ; but the whole of the
possible extract is not obtained by such means, because even in
the case of tender malts a small amount of the starch present is
not hydrolysed, whilst with hard malts a large amount of starch
often escapes conversion.
A method frequently employed to obtain the total available
or "full theoretical " extract consists in treating the ground malt,
previous to mashing, with a cold-water infusion of oats.
Ripe oats (not kiln-dried) contain a considerable amount of the
enzyme cytase, and a cold-water infusion containing this enzyme
is employed to act on the malt for the purpose of liberating the
starch contained in the unmodified portions of the malt by
dissolving the cell walls enclosing the starch granules.
Digest 50 grams of oats, rather finely ground, with 250 c.c.
of cold water, for 3 or 4 hours, and filter. Mix 100 c.c. of the
filtrate with 50 grams of the ground malt experimented with,
and allow the mixture to stand at the room temperature for from
18 to 24 hours. Mash with 250 c.c. hot water, so as to obtain
an initial heat of 151 F. (66 C.), and keep at this temperature
for 1 hour. Transfer the mash to a 515 c.c. flask, and, after
cooling, make up to the mark and filter, and proceed to
determine the specific gravity of the wort in the usual manner.
Before calculating the extract a correction must, however, be
made for the specific gravity of the oat extract used in the
experiment. Determine the specific gravity of the oat extract
used, and subtract one-fifth of its excess gravity above 1000
from the specific gravity of the malt extract. The extract
derived from the malt can then be calculated in the usual
manner.
If the ordinary laboratory extract of the same malt has been
determined, the difference between the two extracts is a measure
of the modification of the malt. The so-called " coefficient of
METHODS OF ANALYSIS 201
modification " may be obtained by calculating the ordinary extract
as a percentage on the " full theoretical " extract. For instance,
if the ordinary extract of a malt is 87 '6, and the "full
theoretical " extract 95 '7, then
87-6x100
""95-7 '
the " coefficient of modification " of the malt, and the value is
comparable with the " coefficient of modification " of any other
malt found in a similar manner.
9. Specific Rotatory Power of Mash Wort. Raise a small
quantity of the 10 per cent, wort derived from the previously
made miniature mash, by Heron's method, to the boiling-point,
cool to 68 F. (20 C.), fill a 1 decimetre tube (100 mm.), place
in the polarimeter, and take a reading. Let us assume the
opticity in a 1 decimetre tube to be 9.
In cases where the wort is too dark in colour to enable a correct
polarimetric reading to be observed, such as when the malt
mashed is highly dried or when colour malts are employed, it
becomes necessary to decolorise the wort before polarising.
To do this take 50 c.c. of the boiled and cooled wort in a 100
c.c. flask, add a few drops of a 10 per cent, solution of lead
acetate, make to mark with distilled water, agitate, and filter
through a dry paper into a dry beaker. Fill a 1 decimetre tube
with this solution at 68 F. (20 C.) and polarise.
Example :
Opticity in 1 decimetre tube = 4 '5.
4'5x2 = 9 on 100 parts of wort, which on 7 '54 dry extract
in 100 parts of wort = 9 x ?. = [a] D 119-4.
10. Acidity. -This is determined by titrating 100 c.c. of the
10 per cent, wort at 60 F. (15 '5 C.) with sodic hydrate,
using litmus as indicator.
Example :
100 c.c. wort required 1'5 c.c. alkali.
1-5 x -009 = -0135 x 10-0-13 percent, on malt.
11. Moisture. For the determination of the moisture per-
centage in malt, it is advisable to have at hand three or four
small bottles of wide mouths and low build. The bottles should
be numbered by marking with a file, and their weights carefully
202 THE BREWER'S ANALYST
ascertained and entered in a convenient book. Marked counter-
poises are sometimes employed, such as are explained with the
specific-gravity bottle.
In estimating the moisture percentage 5 grams of the malt are
weighed, one or two extra corns added, and ground to a fine
powder in a coffee or Seek mill. The powder is then transferred
to the bottle and weighed, withdrawing grist, until exactly 5
grams are weighed. The bottle is then placed iu the water-bath
drying oven and left for 5 hours. This time should not be
exceeded, as, if so, the sample gains in weight owing to oxidation.
At the end of 5 hours the bottle is placed under the desiccator
to cool, 1 hour being the usual time allowed for this purpose.
The weight is now ascertained, the bottle again placed in the
drying oven for a further hour, again cooled under the desiccator,
and weighed.
Example :
Weight of bottle + 5 grams grist . 105'513 grams.
Weight after drying . . . 105 "396
Moisture in 5 grams . '117
117 x 20-2*34 per cent, moisture on malt.
Instead of weighing an exact 5 grams as per the foregoing
experiment, any convenient quantity may be weighed, and a rule
of three sum gives the result, thus :
Weight of bottle 100 '300 grams.
Weight of grist before drying . . ". 5'370
105-670
Weight of bottle + 5 '370 grams grist
after drying 105'544
126
Then A X J^ = 2 ' 34t P ep cent - moisture on malt.
5-370
The above-mentioned method of determining the moisture
percentage in malts is at present considered sufficiently satisfactory
for general purposes ; but in view of the fact that slight oxidation
of the constituents of the malt takes place during drying in this
manner, a much more accurate though complicated method has
been proposed, particulars of which may be found in a paper by
Ford and Guthrie, 1 which consists in drying the sample (ex-
1 Jnl. Fed. List. Brewing, No. 4, 1905, 326-332.
METHODS OF ANALYSIS 203
eluded from the ordinary air) in contact only with an atmosphere
of carbonic acid gas.
MATTERS SOLUBLE IN COLD WATER AND READY-
FORM KD SOLUBLE CARBOHYDRATES.
12. Matters Soluble in Cold Water. The extract for the
determination of matters soluble in cold water may be made so
as to answer also for the determination of colour value, next
described, and also, with dilution, for the estimation of diastatic
power and soluble albuminoids. With this in view, instead of
directly making a 10 per cent, solution as is usual, one of double
strength may be conveniently prepared thus :
Forty grams of the malt are weighed, ground to powder, and
transferred to a stoppered bottle of about 1 litre capacity.
200 c.c. of distilled water at 70 F. (21 C.) are next added, and
the bottle set aside for 3 hours at a temperature of 70 F.
(21 C.), shaking every half hour = 20 per cent, solution. 1
At the end of the 3 hours the extract is filtered, and
50 c.c. at 60 F. (15-5 C.) are added to a 100 c.c. flask and
boiled for 5 minutes. The contents are then cooled and made
to mark at 60 F. (15'5 C.) =10 per cent, solution. 2 This is
then filtered, and the specific gravity taken, from which the
matters soluble in cold water are determined by dividing the
specific gravity, less 1000, by the factor 3*86.
Specific gravity = 1006 '20 - 1000 = 6 '20
6'20 -f- 3-86 = 1-606 dry solids per 100 c.c.
and 1-606 x 10= 16*06 per cent, matters soluble in
cold water expressed on the malt.
1 From this 20 per cent, solution the colour i.s determined as in experiment
14, and a 5 per cent, solution is prepared from it for the determination of
diastatic power as in experiment 19.
Brown and Heron (Jnl. Chem. Soc., 1879, 596) showed that the addition
of sodium hydrate to the cold-water extract completely destroys diastatic
action ; and Ling, in view of this, proposes that the water, before being added
to the bottle, should be rendered slightly alkaline by the addition of 0'02 per
cent, caustic potash, or an equivalent amount of caustic soda or ammonia.
Morris has shown that there is no appreciable attacking and solution of starch
unless the 3 hours' limit of standing is exceeded. The author found that
whereas the matters soluble in cold water at the end of 3 hours were 15 '36
percent., at the end of 6 hours they were 20'33 per cent., and in 24 hours,
24 '74 per cent. ; so that time is a factor of great importance, and in no
instance should the 3 hour limit be exceeded.
' 2 From this 10 per cent, solution is also determined the ash as in experiment
15, and the soluble albuminoids as in experiment 17.
204 THE BREWER'S ANALYST
13. Ready-formed Soluble Carbohydrates. From the
matters soluble in cold water, which have been found to equal
16'06 per cent., the ready-formed soluble carbohydrates are
estimated by deducting the soluble albuminoids, mineral matter,
and acidity, thus :
Matters soluble in cold water . . 16 '06 per cent.
Per cent.
Soluble albuminoids . . . 2'66
Mineral matter . . . . T08
Acidity 0'13
3-87
12-19
The ready- formed soluble carbohydrates are therefore 12' 19 on
100 parts of malt, so that 10 grams malt contain 1*21 to corre-
spond with 100 c.c. of wort.
Where the albuminoids, mineral matter, etc., are not deter-
mined, the ready -formed soluble carbohydrates are always
approximately estimated by subtracting 4 from the matters
soluble in cold water.
14. ColOUP of Wort. In this determination it is necessary
that the wort should possess a gravity near the Excise standard
(1055 or 20 Ibs.), or be calculated to the same. The 20 per
cent, cold-water extract previously prepared for the determination
of matters soluble in cold water answers this requirement, as it
has been shown by Heron that as much colour is extracted from
a malt by cold water as by water at 150 F (65'5 C.). The
determination of colour is therefore most conveniently performed
by filling a 1 inch cell of Lovibond's tintometer with the 20 per
cent, cold-water extract, and employing the 52 series of yellow
glasses.
Example. A 20 per cent, cold-water extract, prepared as
described, filtered and examined in the tintometer, using a 1 inch
cell, required glass No. 5. The colour value is therefore 5.
15. Mineral Matter Or Ash. This is determined by
measuring 50 c.c. of the 10 per cent, cold-water extract at 60 F.
(15*5 C.) and evaporating to dryness over the water bath in a
tared platinum dish. The dish is then placed over a Bunsen
flame and the residue cautiously ignited. At first the residue
swells in the form of a semi-carbonaceous mass, but afterwards
shrinks. Objectionable fumes are often given off, but may be
obviated by applying a light. A strong flame may now be used,
and the dish covered with a piece of platinum foil so as to
METHODS OF ANALYSIS 205
accelerate the oxidation of the carbonaceous matter. 1 The
ignition should be continued until not a glowing particle can be
seen in the ash when the latter is red-hot. Preferably, however,
the dish is placed in a muffle, and the reduction to complete ash
easily effected. When the ash is either grey or brown the latter
indicating the presence of iron the dish is placed under the
desiccator, and when cool, weighed. After weighing, the ash
should be dissolved by means of a little hydrochloric acid, the
dish carefully cleaned, ignited, cooled, and re-tared ; a correction
being necessary should the dish have lost weight, which is
sometimes the case, especially if subjected to prolonged intense
heat.
Example. Fifty c.c. of the 10 per cent, cold-water extract,
evaporated to dryness, incinerated to ash in a platinum dish,
cooled, and weighed.
Weight of platinum dish + ash . . . 16*394
Weight of platinum dish .... 16*340
054
054 x 2 = '108 per cent, ash on wort,
and -108 x 10 = 1 '08 per cent ash on malt.
PROTEIDS OR ALBUMINOIDS.
There are several methods for estimating the proteids or
albuminoids in malt, wort, sugar, beer, etc.; thus we have
Kjeldahl's process, 2 which consists in digesting the substance
in a flask for several hours with an excess of sulphuric acid at
a temperature approaching the boiling-point of the acid, whereby
the greater part of the organic nitrogen is converted into
ammonia, and this conversion is completed by oxidation with
potassic permanganate, which is added as a fine powder in very
small quantities at a time. The addition of permanganate is
continued until the solution becomes green, showing that an
excess has been employed. When cold, the liquid is diluted
with water, rendered alkaline with a strong solution of caustic
soda, and then distilled into a receiver containing a measured
quantity of standard acid (figs. 71 and 72). Kjeldahl's method
1 It is usual to sulphate before incineration, the result being more quickly
and reliably achieved. This is accomplished by adding 2 or 3 c.c. of
sulphuric acid to the wort, evaporating, and burning off in the manner
described.
2 Jnl. Chem. Soc., Abstracts, 1884, 364.
206
THE BREWER'S ANALYST
was quickly taken up by other investigators, C. Arnold 1 suggest-
ing a slight modification and Gunning 2 proposing another.
We have also the older methods, such as burning the organic
substance with copper oxide and copper so as to obtain all the
nitrogen as a gas, and the well-known method by which the
substance is mixed with soda lime and burned so as to decompose
the nitrogenous substance to ammonia. Kjeldahl's process,
however, either as originally proposed or with slight modification,
is usually resorted to in ordinary routine work ; but for a thorough
investigation as to its accuracy, the reader is referred to the first
volume of the Transactions of the Guinness Research Laboratory.
For all ordinary purposes, however, the following modification
of Kjeldahl's method is sufficiently accurate :
Fio. 71.
From 1 to 5 grams (according to richness in nitrogen) of the
substance is introduced into a flask of hard Jena glass, and
treated with 10 or 20 c.c. of strong sulphuric acid and 5 grams
of potassic sulphate. The flask is then heated over a Bunsen
flame very gradually, and after frothing has ceased, the heat
is increased to brisk boiling and continued until the liquid
gradually becomes clear and colourless. The contents of the
flask are then cooled, washed into a distilling flask, a sufficient
quantity of sodium hydrate to more than neutralise the acid is
quickly added, arid the flask then connected with the condensing
apparatus and the ammonia distilled over into a flask containing
a known quantity of a standard sulphuric acid. The loss of
acidity is then finally determined in the usual way, and expressed
as nitrogen or albumin. In figs. 71 and 72 we have a series of
* Jnl. Chem. Soc., Abstracts, 1885, 930, and 1887, 78.
2 Ibid., 1889, 796.
METHODS OF ANALYSIS
207
flasks in which to digest the substance, a series of distilling flasks
each connected with a condensing tube, and a series of flasks to
contain the standard acid.
Example :
16. Total Albuminoids. Two grams of the malt are
weighed, ground to powder, and placed in a boiling flask. Ten c.c.
of strong sulphuric acid and 5 grams of potassic sulphate are added,
and the flask placed over a flame and the contents gradually
raised in temperature. After frothing has ceased, the heat is
increased to boiling-point and the heating continued until the
FIG. 72.
contents become colourless or possessing but a pale yellow tinge.
The contents of the flask are now cooled, washed into a distilling
flask with about 100 c.c. of ammonia free water, about 40 c.c.
of sodium hydrate added, and a few pieces of pumice-stone or
pipe-clay to prevent bumping. The flask is then connected
with the distilling apparatus and the contents distilled, the
N
distillate being collected in a flask containing 75 c.c. - sulphuric
acid. When about 100 c.c. of the distillate has been collected,
the whole of the ammonia produced by decomposition of the
proteid bodies will have passed over and have been absorbed and
N
neutralised by the acid.
The acidity of the distillate is now tested by adding a few
208 THE BREWER'S ANALYST
drops of methyl-orange as indicator and titrating with
ammonia; the number of c.c. required being deducted from the
quantity of acid placed in the flask (75 c.c.), equals the
20
number of c.c. of acid neutralised by the ammonia produced by
the decomposition of the proteids originally in the malt.
N
Each c.c. of acid equals '0007 nitrogen. Taking the
20
albuminoids as containing 15*7 per cent, of nitrogen, we calculate
the quantity of albuminoids to which the nitrogen corresponds.
The factor 6 '33 is used for this purpose. In titrating the
N
distillate with ammonia, suppose the quantity required to
20
N
neutralise the acid equalled 34'60 c.c. Then 75'00-
N
34*60 c.c = 40 '40 c.c. acid neutralised by the ammonia
derived from the albuminoids originally contained in 2 grams of
malt, and 40'40 x -0007 = '028280 x 50 = 1-414000 x 6'33 = 8'94
per cent, total albuminoids on the malt.
A correction is necessary for the nitrogen in the reagents used
and for the action on the glass apparatus, and it is advisable in
all instances to perform a blank experiment and deduct the
ammonia so found.
17. Soluble Albuminoids. Ten c.c. of the 10 per cent,
cold-water extract employed for the determination of matters
soluble in cold water (p. 203) are run into a boiling flask and
evaporated to dryness on the water bath. Ten c.c. of sulphuric
acid and 5 grams of potassium sulphate are now added and the
mixture heated, at first gently, until the first violent action is
over, and afterwards strongly, until the liquid is decolorised.
The liquid is now transferred to the distilling flask with about
100 c.c. of ammonia free water, about 40 c.c. of sodium hydrate
added, and a few pieces of pumice-storie or pipe-clay to prevent
bumping. The flask is then connected with the distilling
apparatus and the contents distilled, the distillate being collected
N
in a flask containing 50 c.c. - sulphuric acid. When about
'20
100 c.c. of the distillate has been collected, the whole of the
ammonia produced by decomposition of the proteids will have
passed over and have been absorbed and neutralised by the
N aci d.
20
METHODS OF ANALYSIS 209
The acidity of the distillate is now tested by adding a few
N
drops of methyl-orange as indicator and titrating with
^0
ammonia ; the number of c.c. required being deducted from the
N
quantity of acid placed in the flask (50 c.c.), equals the number
of c.c. of acid neutralised by the ammonia produced by the de-
composition of the proteids originally in the malt wort.
N
Each c.c. of acid equals '0007 nitrogen. Taking the album-
20
inoids as containing 15*7 per cent, of nitrogen, we calculate the
quantity of albuminoids to which the nitrogen corresponds by
the use of the factor 6*33, thus
N
In titrating the distillate with ammonia, suppose the
.20
N
quantity required to neutralise the acid equals 44 '0 c.c.
.20
Then 50*0 c.c. - 44'0 c.c. = 6-0 c.c. x -0007 = "00420 x 100 - '42000
x 6-33 = 2*66 per cent, soluble albuminoids on the malt.
18. Insoluble Albuminoids. The soluble albuminoids de-
ducted from the total albuminoids denote the insoluble, thus :
Total albuminoids . . . 8 '94 per cent.
Soluble 2-66
Insoluble 6'28
19. Diastatie Power. A 5 per cent, solution of cold-water
malt extract is prepared by taking 50 c.c. of the former 20 per
cent, cold-water extract, detailed under the determination of
matters soluble in cold water (p. 203), and making up to 200 c.c.
with distilled water at 60 F. (15'5 C.). 1 Now take twelve
1 It will be observed (p. 203) that the 20 per cent, cold-water extract is
allowed to stand for exactly three hours at 70 F. (21 C.). The time of
standing, up to six hours, does not interfere with the diastatic power, so long
as the temperature is a constant 70 F. (21 C.), but if the temperature is
increased the diastatic power of the extract varies, as the following will show :
Diastatic power taken after cold-water extract stood
For 1 hour. 3 hours. 6 hours.
D. P. 29 29-4 29'4
Temperature of digestion. Diastatic power.
29-4
37-7
57-1
14
210 THE BREWER'S ANALYST
Nessler or other glass tubes of about 50 c.c. capacity marked
1 to 12 (these are best arranged in order in the star apparatus
devised by Reischauer), and add to each tube 10 c.c. of soluble
starch solution prepared as described under Standard Solutions
(p. 144). Now fill a graduated 5 c.c. pipette with the 5 per
cent, cold-water extract, and add to the first tube *1 c.c., to the
second tube -2 c.c., to the third tube -3 c.c., and so on up to
the twelfth tube 1 "2 c.c. Shake the tubes and place them in the
water bath, and maintain for exactly one hour at a temperature
of 70 F. (21 C.). Now add to each tube 5 c.c. of Fehling's
solution (i.e. 2'5 c.c. copper sulphate, and 2 '5 c.c. alkaline tartrate),
shake the tubes and place them in boiling water, and leave them
for five minutes. At the end of this time remove the tubes
and allow them to stand for five minutes. Now note the
tube in which the blue colour has entirely disappeared. It
often happens that there is a blue colour in one tube, and
the next is overdone, that is, the colour is yellow In such
case the mean of the two is taken. For instance, suppose
the third tube, containing '3 c.c. of wort, is blue, and the fourth
tube, containing *4 c.c. of wort, is overdone. In such instance
the mean, viz. '35, is taken, and with practice it is easy to
judge even more accurately, reading to one-fourth the value
between each tube. Thus the third tube may be quite blue,
the fourth only slightly overdone, in which case a reading of
325 is taken.
Lintner, to whom we are indebted for this test (see p. 108),
bases his standard as follows:
The diastatic power of a malt is to be taken at 100 degrees,
when "1 c.c. of a 5 per cent, solution of malt extract just reduces
5 c.c. of Fehling's solution.
Example. The end point was found to lie between the third
and fourth tube ; the amount of malt extract to be taken is there-
fore -3 + '4 -r 2 = -35, and 122 x ] = 28'57.
3o
This figure must be calculated upon water-free malt. Our malt
is found to contain 2'34 per cent, of moisture; then 100 - 2'34 =
97-66, and -122. x 28'57 = 29'25.
97 66
The cold-water extract, however, itself contains a small
amount of reducing sugars, and a correction for these
must be made. This may be accomplished by conducting a
blank experiment, or the more usual practice is to reckon
that such reducing sugars are equal to 1'4. We therefore
METHODS OF ANALYSIS 211
have 29-25 - 1*4 = 27*85 diastatic power of malt on Lintner's
scale.
Instead of performing the operation as just described, the
following method may be adopted :
Three c.c. of the 5 per cent, cold-water extract is allowed to
act on 100 c.c. of a 2 per cent, solution of soluble starch at 70 F.
(21 C.) for one hour in a 200 c.c. flask.
N
Ten c.c. of caustic alkali is then added, in order to stop
further diastatic action, the liquid cooled to 60 F. (15*5 C.),
made up to 200 c.c. with distilled water at the same temperature,
well shaken, and titrated against 5 c.c. portions of Fehling's
solution, using ferrous thiocyanate as indicator.
The titration is carried out as follows :
Five c.c. of Fehling's solution are accurately measured into a
150 c.c. boiling flask. The converted starch solution is added
from a burette, in small quantities at first of about 5 c.c., the
mixture being kept rotated and boiled after each addition until
reduction of the copper is complete, which is ascertained by
rapidly withdrawing a drop of the liquid by a glass rod, and
bringing it at once in contact with a drop of the indicator on a
porcelain or opal glass slab.
Our analysis now works out as follows :
MALT ANALYSIS.
1. Extraneous matters (per cent.) . . . 1'2
2. Defective corns (per cent.) . . . 1 '0
3. Weight per bushel (Ibs.) .... 42
4. Steely corns (per cent.) .... 2
5. Specific gravity (10 per cent. wort). Seek 25 1029'! 1
6. Extract per quarter (336 Ibs.) . . . 97'80
7. Dry extract (per cent.) . . . 75*41
8. Saccharification period (minutes) . . 25*00
9. Specific rotatory power of mash wort . 9 = [a] n l!9*4
10. Acidity (per cent.) . . . . 0*13
11. Moisture (per cent.) . . . . . 2 '34
12. Matters soluble in cold water (per cent.) . 16*06
13. Ready-formed soluble carbohydrates (per cent.) 12*19
1 In the examination of green malts, where the diastatic power often exceeds
100, the malt, extract is diluted with an equal volume of water before being
added to the tubes containing the soluble starch, the result being multiplied
by 2.
212 THE BREWER'S ANALYST
14. Colour of wort 5
15. Mineral matter or ash (per cent.) . . T08
16. Total albuminoids (per cent.) . . . 8*94
17. Soluble albuminoids (per cent.) . . . 2'66
18. Insoluble albuminoids (per cent.) . . 6 '2 8
19. Diastatic power 27*85
WORT ANALYSIS.
Some few years ago the analysis of wort, as far as the carbo-
hydrate constituents are concerned, consisted in first making a
certain per cent, solution according to the gravity, taking a
definite quantity, and conducting a Fehling's test, so as to obtain
the cupric reducing power from which the percentage of maltose
was first calculated, and afterwards the percentage of dextrose
which such maltose would yield by hydrolysis. A further
percentage solution of the wort was then made, and a definite
portion inverted for a certain time at the boiling temperature, with
the addition of 5 c.c. hydrochloric acid, after which it was cooled,
neutralised, made to bulk, and the cupric reducing power again
estimated and calculated to percentage on the wort. From these
two results (before and after inversion) the former calculated
dextrose was deducted from the reducing bodies obtained after
inversion, and the result multiplied by - 9 gave the actual amount
of dextrin. We thus obtained both the percentage of maltose
and dextrin which the wort was supposed to contain. Now this
was all very well in its way, but within recent years it has been
shown that malt contains reducing sugars (ready-formed soluble
carbohydrates) such as dextrose, levulose, and cane-sugar, so that
unless we first take account of and deduct these we shall actually
be attributing their presence in wort as due to the conversion of
our starch, which is not so. Again, the inversion by the aid of acid
results in the formation of inert bodies by reason of a decomposi-
tion of the end-products of inversion, the ready-formed cane-sugar
being hydrolysed to dextrose, and some of the albuminoids trans-
formed into actual cupric reducing bodies.
There can be no doubt under these circumstances that, with
worts, the inversion method is to be condemned, and in its stead
the carbohydrates estimated by the aid of the polarimeter. The
total sugars are therefore now estimated from the cupric oxide
reducing power, after deducting those ready formed, calculating
to maltose, and then multiplying the maltose by the specific
rotatory power of the wort,^so obtaining the angle due to maltose,
METHODS OF ANALYSIS 213
and deducting this from the total rotatory power so as to obtain
the angle due to dextrin ; the latter angle is then divided by the
rotatory power of 1 part dextrin, which gives at once the percentage
of dextrin present in the wort.
MALT WORT.
The method proposed as regards malt wort was originally
devised by Heron, and is essentially as hereafter detailed, the
following being the determinations to be made :
/ 1. Dry extract per cent.
Hot mash wort . j * S P eoifio rotator y P ower '
3. Cupnc oxide reducing power.
4. Acidity.
5. Matters soluble in cold water.
6. Ready-formed soluble carbohydrates.
7. Soluble proteids or albuminoids.
Cold-water extract -, g gpecifi( , rotatory power _
9. Cupric oxide reducing power.
^0. Mineral matter or ash.
In the ordinary course of events, had it been our primary
intention to analyse the wort from the previously examined malt,
most of these results would be carried forward. If they have
not been determined, it becomes essential to make a 10 per cent,
mash wort and carry out the experiments. We may, however,
to save repetition, carry the results of our malt analysis forward,
thus :
1. Dry Extract per cent, or Total Solids. Determined
as explained under Malt Analysis.
Example. The specific gravity of 10 per cent, hot mash wort
= 1029-10 -1000 = 29-11-^3-86 = 7-54 dry solids per 100 c.c. of
wort.
2. Specific Rotatory Power of Hot Mash Wort.
Determined as explained under Malt Analysis.
Example. Opticity of 50 per cent, solution at 68 F. (20 C.)
in a 1-decimetre tube= 4'5 x 2 = 9 on 100 parts of wort.
3. Cuprie Oxide Reducing 1 Power of Hot Mash Wort.
The determination of the reducing sugars is one of the most
important estimations in brewing analysis, and as this depends
largely on the reduction of Fehling's solution, it is advisable to
give in some detail the exact method in which the reductions
are made.
214 THE BREWER'S ANALYST
In estimating the cupric reducing power, careful attention
must be paid to the following points :
(1) The exact composition of the Fehling's solution as regards
copper, and the nature and amount of the alkali it contains.
(2) The degree of dilution of the Fehling's solution.
(3) The restriction of the amount of copper reduced within
certain prescribed limits.
(4) The mode of heating the solution, and the time occupied in
reduction.
Having regard to the foregoing, the normal conditions under
which all determinations should be made are :
(a) The use of Fehling's solution prepared as described under-
Standard Solutions.
(b) The degree of dilution of the copper solution, taking into
account the volume of the saccharine solution added, should be
one part of Fehling's solution to one part of water.
(c) An amount of the reducing sugar should be taken which
will give a weight of CuO lying within the limit of 0*15 to 0'35
gram.
(d) The diluted Fehling's solution should be heated in a
suitable beaker in a boiling-water bath until the temperature is
constant, and then the weighed or accurately measured volume
of liquid containing the reducing sugar added, arid the heating in
the water-bath continued for exactly 12 minutes, the beaker
being covered with a clock-glass during the whole period of
heating. The nitration should be performed as rapidly as
possible through a carefully folded paper, and the paper then
dried and burned off in a tared crucible over a Bunsen flame in
the usual way, and after cooling, the contents weighed as cupric
oxide.
Example. Fehling's solution is first diluted as follows :
25 c.c. of the copper solution and 25 c.c. alkaline tartrate are
added to a beaker together with 30 c.c. of distilled water. The
beaker is then placed in the boiling-water bath, and when its
contents are brought to the boiling-point 20 c.c. of the 10 per
cerrt. mash wort are added, and the whole boiled for 12 minutes.
The beaker is then removed and the contents filtered. A good
filter paper should be used, or otherwise some of the CuO is liable
to pass through. If such were the case, it would, after standing,
be found at the bottom of the beaker which has received the
filtrate, in which case it becomes essential to refilter. Wash the
precipitate time after time, using for this purpose about 200 c.c.
of boiling water, and finally wash with about 10 c.c. of strong
METHODS OF ANALYSIS 215
alcohol, then dry the filter in the water oven, transfer to a tared
crucible and burn off, ignite to redness for 15 minutes, cool under
the desiccator and weigh, repeating the heating, cooling, and
weighing until the weight is constant.
Example ;
Weight of crucible and CuO . . 6'780 grams
Weight of crucible . . . 6'633
147 i
147 = amount in 20 c.c. of 10 per cent, solution of wort, or 2 c.c.
of wort. Then '147 x 50 = 7 '35 grams in 100 c c. of wort.
4. Acidity. This is determined as in Malt Analysis by
N
titrating 100 c.c. of the 10 per cent, wort with alkali, using
litmus as indicator.
Example, 100 c.c. of 10 per cent, wort required 1*5 c.c.
alkali. 1-5 x -009 = '0135 acid in 100 c.c. of wort.
5. Matters Soluble in Cold Water. These are determined
exactly as in Malt Analysis.
Example. Specific gravity of cold-water extract = 1006-20.
1006-20 -1000 = 6-20 -=-3-86 = 1'60G dry solids per 100 c.c. of
solution.
6. Ready-formed Soluble Carbohydrates. Also deter
mined as in Malt Analysis.
Per cent,
on malt.
Matters soluble in cold water . . 16*06
Per cent.
on malt.
Soluble albuminoids . . . 2 -6 6
Mineral matter or ash . . . 1'OS
Acidity . . . . 0*13
3-87
12-19
The ready-formed soluble carbohydrates on 100 parts of malt =
12'19, so that 10 grams of malt contain 1'21 to correspond with
100 c.c. of wort.
7. Soluble Proteids Or Albuminoids. These are deter-
mined as in malt analysis, under Soluble Albuminoids.
10 c.c. of the 10 per cent, cold-water extract evaporated to
dryness in a boiling flask ; 10 c.c. of strong sulphuric acid and 5
1 This figure, it will be noticed, is rather low.
216 THE BREWER'S ANALYST
grams of potassic sulphate added, the contents warmed and then
boiled until the solution is clear ; then added to a distilling flask
with about 100 c.c. distilled water, about 40 c.c. sodic hydrate
added together with a few pieces of pumice, the flask connected
with the distilling apparatus and the contents distilled, the
N
distillate being collected in a flask containing 50 c.c. sulphuric
20
acid.
100 c.c. of the distillate having been collected, the acidity is
tested :
N N
Example. 50 c.c. acid required 44 c.c. - alkali to effect
neutralisation.
50 - 44 = 6-0 c.c. x -0007 = -00420 x 10 = -04200 x 6'33 = -26
albuminoids in 100 c.c. of cold-water extract.
8. Specific Rotatory Power of Cold water Extract. A
small quantity of the extract is boiled and then cooled to 68 F.
(20 C.). A 2 decimetre tube is then filled with the same, placed
in the polarimeter, and a reading taken. The reading, divided by
2, gives the reading of a 1 -decimetre tube.
Example. Opticity in 2-decimetre tube = 0'60. 0'60 -f 2 = 0'30.
9. Cupric Oxide Reducing* Power of Cold water Extract.
Determined as with the 10 per cent, hot mash wort (p. 213).
Example. CuO obtained = '282 amount in 20 c.c. -282x5 =
1'41 gram on 100 c.c. of 10 per cent, malt extract to correspond
with 100 parts of wort.
10. Mineral Matter or Ash. Determined as per Malt
Analysis. 50 c.c. of the 10 per cent, cold-water extract evaporated
to dryness in a tared platinum dish, after sulphating; then
ignited to ash, cooled, and weighed :
Weight of platinum dish + ash . . . 16-394
Weight of platinum dish .... 16 '340
054
054 x 2 = -108 per cent, on wort.
We now deduct the figures obtained from experiments with
our cold-water extract from the corresponding determinations of
our hot wort, thereby arriving at figures due entirely to starch
products. Our results are therefore worked out as follows :
w , Cold-water Conversion Products
Extract. due to Starch.
Cupric oxide reducing power 7'35 - 1'41 = 5'94
Specific rotatory power . 9'00 - 0'30 = 8'70
METHODS OF ANALYSIS 217
Each gram of cupric oxide, according to Fehling's factor, equals
7435 grain of maltose; we therefore obtain the amount of
maltose in the wort by multiplying the cupric oxide obtained by
this factor.
5*94 (CuO due to starch products) x '7435 = 4*44 maltose in the
wort expressed in percentage on the wort.
The specific rotatory power of 100 grams of maltose, when
observed in a 1-decimetre tube, is [a] Dg . 86 = 135'9 ; therefore
1 gram = T359 . The amount of maltose calculated equals 4'44 ;
so this, multiplied by 1*359, = 6*03 angle due to maltose. Deduct-
ing this angle from the total angle of starch products, we get the
angle due to dextrin.
The specific rotatory power of 100 parts of dextrin = [a] D3 . 86
194-4 , or 1 part= 1*944; therefore the remaining specific rotatory
angle, divided by 1'944, gives the amount of dextrin expressed in
percentage on the wort.
Example. Total angle = 8'70 - 6 '03 = 2*67 due to dextrin, and
*2'fi7
JLrL.1-38 dextrin in 100 parts of wort.
100 parts of the wort therefore contain :
Maltose (due to starch conversion) . . . 4 '44
Dextrin (due to starch conversion) . . . 1'38
Ready-formed soluble carbohydrates . 1-21
Proteids or albuminoids ..... -26
Mineral matter or ash . . . . . '10
Other bodies by difference . . . . "15
Total dry solids . . .7-54
It is usual to express the composition of wort in percentage on
its dry extract, as this permits of a comparison of the composition
irrespective of gravity. This is performed by ordinary rule of
three, thus :
Dry extract
7'54 : 4-44 (maltose) : : 100 58*87
1-38 (dextrin) : : 100
1*21 (ready-formed
sugars) : : 100
26 (albuminoids) : : 100
10 (ash) : : 100
15 (other bodies) : : 100
18-32
16-05
3-44
1-33
1-99
100-00
218 THE BREWER'S ANALYST
The specific rotatory power of the wort is similarly calculated
on the dry extract :
Dry Extract. Sl-ific Rotatory
7-54 : 9-0 :: 100: |>] D 119-4 .
KAW-GRAIN WORT ANALYSIS.
In our former analysis we have dealt with wort obtained
entirely from malt, but it is hardly necessary to mention that
similar analysis may be performed by conducting our mashing
operation with a mixture of malt and prepared raw grain, such
as flaked or granulated maize or rice, in such proportions as is
carried on practically in any particular brewery. It may also
be necessary to conduct our mashing operation with malt and
unprepared raw grain, such as maize or rice grits. In such
instances it therefore becomes necessary to take a similar pro-
portion of the one or the other as is being used in practice,
gelatinise the starch, and cool the same to 150 F. (65 '5 C.)
before mixing with our malt mash.
In all such instances we merely reduce the percentage of malt
in accordance with the percentage of raw grain employed, obtain-
ing the usual 10 per cent, wort both with our mash and our
cold-water extract, our results being then obtained precisely as
described in malt and malt-wort analysis. It is obvious, however,
that this essential method of procedure with different percentages
of raw grain, raises grave difficulties to the standardisation of
analysis (see p. 231).
MASH-TUN WORT ANALYSIS.
In many breweries it is a general custom, and an excellent
one, to test the wort obtained from every mash in order to
ascertain whether the conversion has been rightly conducted and
the proper ratio of dextrin to maltose obtained.
With pale ale and so-called " stock ale," the dextrin percentage
should undoubtedly be greater than for a mild or running beer,
so that by testing the mash-tun worts any change in character of
materials used or variation in mashing or sparging may at once
be detected.
Mash-tun wort to be tested should be collected from the taps
at two different periods : first, a sample should be taken exactly
15 minutes from setting taps ; and secondly, a further sample
after the sparge liquor has got well through the goods, say
METHODS OF ANALYSTS 219
exactly 2 hours after setting taps. The two samples should
then be well mixed together, boiled for a minute or two, cooled
to 60 F. (15*5 C.), and the specific gravity taken. The specific
gravity should then be reduced to 1050 and a polarimetric
reading taken with the wort at a temperature of 68 F.
(20- C.).
Example. (a) Sample of wort collected from inash-tun taps 15
minutes after setting, sp. gr. 1078 '96. (b) Sample taken 2 hours
after setting taps, sp. gr. 1025*28.
The two samples mixed together = sp. gr. 1052' 12. 50 c.c. of the
wort at 1052 '12, reduced in gravity to 1050 by the addition of
2*12 c.c. water, and the solution raised to the boiling-point.
Now, before a polarimetric reading can be accurately taken, the
wort must be perfectly clear. Wort taken from the mash-tun
taps, on cooling, is never clear ; it therefore becomes necessary to
render it so; and in order to do this, 100 c.c. of the wort at a
specific gravity of 1050, after raising to the boiling point, is run
into a 200 c.c. flask together with 10 c.c. of a 10 per cent, solution
of lead acetate, made to 200 c.c. with distilled water, thoroughly
mixed and filtered through a dry filter paper into a clean dry
beaker = 50 per cent, solution.
The specific rotatory power is now taken in a 1 decimetre tube,
with the wort at a temperature of 68 F. (20 C.) ; reading x 2 =
opticity of the wort.
COPPER-WORT ANALYSIS.
In the analysis of wort from the copper, the following are the
determinations to be made :
1. Specific gravity.
2. Dry extract per cent.
3. Cupric oxide reducing power.
4. Specific rotatory power.
5. Proteid bodies or albuminoids.
6. Mineral matter or ash.
From the third and fourth determinations we arrive at the
percentage of dextrin and maltose in the wort.
As previously cited, malt contains ready-formed soluble carbo-
hydrates ; and unless we estimate their amount and deduct them
from our results, we shall be attributing their presence to
the conversion of starch at the mashing stage. It is therefore
necessary to estimate the cupric oxide reducing power and the
220 THE BREWER'S ANALYST
specific rotatory power of a cold-water extract made from a sample
of the malt employed in mashing, and deduct these results from
the results obtained with the copper wort. We may then
determine the albuminoids and mineral matter from the copper
wort itself.
Now, provided any of these results have already been determined,
such as they would have been had we already analysed the malt
or a cold-water extract produced from it, our results may be
carried forward ; and it only becomes necessary to find the factor
by which to multiply our cold-water extract results to make them
correspond with a wort of the same percentage of dry solids as
our copper wort.
The following example will make this clear :
Sp. gr. of copper wort = 1045 - 1000 = ^1 = 11'66 dry solids
3*86
per 100 c.c.
9Q-1 1
Sp. gr. of laboratory 10 percent. wort = 1029'11 - 1000 = -~
o'oo
= 7-54 dry solids per 100 c.c.
1 1 fifi
,- - = 1*54 factor by which to multiply 10 per cent, cold-water
extract results in order to make them correspond with a wort
of the same percentage of dry solids as our copper wort
(viz. 11-66).
An analysis of our copper wort gives, say, CuO per 100 c.c. =
11-42.
An analysis of our copper wort gives, say, specific rotatory
power = 14 '43.
Our cold-water extract results gave CuO per 100 c.c. = 1*41.
Our cold-water extract results gave specific rotatory power 0'30.
Hence corrections to correspond with our copper wort are :
CuO 1-41 x 1-54 = 2-17.
Specific rotatory angle . . 0*30 xl '54= '46.
Which give figures due to maltose and dextrin as follows :
CuO 11-42 -2-17 = 9-25.
Specific rotatory angle . . 14-43 - -46 = 13-97.
Then 9-25 x -7435 = 6*87 per cent, maltose on the wort,
6 '87 x 1'359 = 9-34 specific rotatory power due to maltose,
13*97 - 9'34 = 4'63 specific rotatory power due to dextrin,
and 4-63 -"-1-944 = 2*38 per cent, dextrin on the wort
METHODS OF ANALYSIS 221
The copper wort therefore contains :
Carried forward. Maltose 6-87percent.
Dextrin 2 -38
Ready-formed soluble carbohydrates 1*21 x 1*54 . 1*86
Soluble albuminoids 0-26 x 1-54 . . . -40
Mineral matter O'lO x 1 '54 -15
11-66
Which may be expressed as percentage composition thus :
Dry extract
11-66 : 6-87 : : 100 : 58'92 maltose.
2-38 : : 100 : 20'41 dextrin.
1'86 : : 100 : 15'95 ready formed soluble carbohydrates.
40 : : 100 : 3'43 albuminoids.
'15 : : 100 : 1-29 mineral matter.
100-00
Should it be desired to express the maltose and dextrins in
terms of malto-dextrins, this may be performed as hereafter
described.
MALTO-DEXTRINS OR AMYLOINS IN WORT.
It will have been seen that in our former wort analysis we
have returned the starch transformation products as maltose
and dextrin only, but from a perusal of our remarks, p. 79, it is
evident that the products of the hydrolysis of starch by diastase
include not merely maltose and dextrin, but combinations of
the two, termed malto-dextrins or amyloins.
Moritz and Morris 1 describe a method for the determination
of the malto-dextrins based on the assumption that the free
maltose is completely fermentable by primary yeast, any reducing
sugars found after such fermentation being therefore due to
combined maltose, existing as malto-dextrin ; the combined
dextrin being determined by hydrolysing it into maltose by
means of cold-water extract, and then determining the increase
in reducing sugars.
The method of analysis is as follows :
(1) A diastatic solution to be used for hydrolysing the malto-
dextrins is first prepared thus :
200 grams of finely ground highly diastatic malt are added to
1 ^Text-book of the Science of Brewing.
222 THE BREWER'S ANALYST
500 c.c. of distilled water, well stirred, and allowed to stand in
a cool place over-night. It is then filtered, the bright nitrate
being used for the subsequent determinations.
The reducing power of this solution is now ascertained :
10 c.c. of the filtrate are diluted to 100 c.c., digested 1 hour
at 130 F. (54'4 C.), then cooled, and the reducing power estimated
on 10 c.c. (=1 c.c. of cold-water extract).
CuO obtained = 0'074 gram.
This correction must be made when the solution is employed.
(2) The percentage of dry solids in the wort is now determined
by taking the specific gravity and dividing the excess weight
over 1000 by the solution factor 3-86. Thus sp. gr. = 1045.
.'. . = 11 '65 per cent, dry solids.
o'$G
(3) Determination of Combined Maltose, (a) Reducing
Power of Wort after removal of free maltose by fermentation with
yeast. Fifty c.c. of the wort are taken, placed in a small flask,
"25 gram of washed pressed yeast added, the mouth of the flask
loosely plugged with cotton-wool, the flask placed on the forcing
tray, and the contents allowed to ferment at 80 F. (26'6 C.)
for 48 hours.
The wort is now boiled to expel the alcohol, cooled to 60 F.
(15'5 C.), diluted to 100 c.c., a small quantity of alumina or
kieselguhr added to assist clarification, then filtered, and the
reducing power determined on 25 c.c. of the bright filtrate.
CuO obtained = 0'196 gram.
(b) Reducing Power of the Wort after removal of free maltose
and maltose in malto-dexlrin, by diastatic hydrolysis and yeast
fermentation. Fifty c.c. of the wort are fermented as previously
described, but with the addition of '25 c.c. of diastatic solution as
well as yeast (to hydrolyse the malto-dextrins).
Fermentation being complete, the solution is boiled to expel
the alcohol, cooled to 60 F. (15'5 C.), a little alumina or
kieselguhr added, the whole made up to 100 c.c., filtered, and
the reducing power determined on 25 c.c. of the bright filtrate.
CuO obtained = 0-1 30 gram.
This is due to the reducing bodies in the wort, other than
maltose, and must be deducted from the amount found in the
former experiment 3 (a). Therefore -196 - '130 = -066 CuO due
to combined maltose. The 25 c.c. of reduced wort used contained
METHODS OF ANALYSIS 223
12 '5 of original wort; therefore, by multiplying by 8, we have
the CuO due to maltose per cent, on the wort.
066 x 8= '528 CuO in 100 c.c. wort, and
528 x -7435= ^392 combined maltose.
This, calculated on the dry solids, gives :
'392 x .. _ = 3 '36 per cent, maltose in motto-dextrin.
4. Determination of Combined Dextrin. (a) Reducing
Power of Wort. Two hundred c.c. of the wort are diluted to 100
c.c., 10 c.c. of this solution ( = 2 c.c. wort) are now taken, and a
gravimetric estimation of the sugar made, just as described under
Wort Analysis.
CuO obtained = 0-282.
(b) Reducing Power of the Wort after digestion with cold-water
malt extract. Twenty c.c. of the wort are taken, 2 '5 c.c. of the
previously prepared diastatic solution added, and the whole
maintained in a water bath for 1 hour at 130 F. (54 '4 C.).
The solution is now cooled and diluted to 100 c.c., and the
reducing power determined in 10 c.c.
CuO obtained = 0-324.
As the cold-malt extract used contained some reducing bodies,
the amount of CuO due to these must be deducted. As 1 c.c. of
the cold extract gave 0'074 CuO, a deduction of 0'018 due to
'25 c.c. must be made from the total CuO obtained.
Total CuO 0-324
Deduction for cold-water extract 0-018
0-306
The CuO due to the maltose and reducing bodies naturally
present in the wort amounted to 0*282 gram. Therefore 0'306 -
0-282 = 0-024 CuO due to maltose from the hydrolysis of the
combined dextrin in 2 c.c. of wort, and 0'024 x 50= 1'20 CuO
in 100 c.c., and 1'20 x 706 x = '847 combined dextrin in 100 c.c.
1 00
of wort, or 11-65 dry solids. Then -847 x __ = 7'27 per cent.
1 1 "(3t)
of combined dextrin on the dry solids.
1 The factor '706 is obtained by multiplying that for maltose, viz., '7435 x
'95, as 1 part of maltose is produced from "95 part of dextrin.
224 THE BREWER'S ANALYST
Our results expressed on the dry solids work out thus :
Maltose in malto-dextrin . . . .3*36
Dextrin in malto-dextrin. 7'27
Total malto-dextrin . . 1O63
It will be seen that the method is rather lengthy and tedious,
and is open to the objection that its accuracy must in a great
measure depend upon the type of yeast employed to bring about
the fermentation. It is a process, however, which gives some
useful information and at times is necessary to carry out.
RAW-GRAIN ANALYSIS.
Of this class of material we have unprepared varieties such as
barley, sago, tapioca, oats, maize, and rice. Of these barley gives
a wort possessing a raw, objectionable flavour, and therefore has
not been found an advantageous material to employ ; sago and
tapioca are expensive, and oats are only of use for the production
of a particular kind of stout, as, owing to their high content of
albuminoids and oily matter, they produce definite flavour and a
cloudy wort. We thus narrow down to maize and rice.
Maize contains from 3 to 5 per cent, of oil which suffers decomposi-
tion at the boiling temperature, imparting offensive odours to wort,
and on this account cannot be employed in its raw state. Within
recent years, however, means have been devised for removing .the
oil; and raw maize freed from oil, and now known as "grits," has
become a valuable malt adjunct. The oil in maize is principally
contained within the germ, so that it is merely necessary, in order
to produce it practically free from oil, to grind it through fluted
rollers and afterwards screen it with the help of an air-blast, by
which the germ and hull and starchy portion may be separately
collected. Rice as it comes into this country is dehusked, and is,
practically speaking, free from oil and other deleterious substances,
and hence is a unique brewing material.
We thus have raw maize grits on the one hand and raw rice
on the other, either of which may be employed by the brewer.
The cheapness of these raw materials in comparison to the large
percentage of starch they contain, and the high extract derivable
from their manipulation, is a strong factor in favour of their use,
but unfortunately there exists the fact that it becomes necessary
to first gelatinise the starch prior to mashing. In order to do
this it is necessary, on the practical scale, to infuse the material
METHODS OF ANALYSIS 225
for about one hour at a temperature of 190 F. (87*7 C.) with
constant stirring, and hence a specially constructed conversion
vessel is generally used, so that the starch may be gelatinised and
the solution cooled to a temperature below that at which diastase
is destroyed before passing to the mash-tun or otherwise mixing
in the ordinary malt grist. In order to obviate the necessity of
the brewer carrying out this necessary prior starch gelatinisation,
manufacturers years ago undertook the performance of this
object, with the result that prepared maize and rice were placed
on the market.
These materials are therefore now cooked so as to burst the starch
cells, and are then dried, in which condition they may be directly
employed in the mash-tun, the starch becoming more or less soluble
at the ordinary initial mash temperature of 150 F. (65*5 C.).
The usual mode of preparation is to grind the material through
fluted rollers (in the case of maize grits this will have already
been done), and then pass it to a revolving perforated hopper
which is jacketed so that steam may be injected and made to
permeate the grain. Here the grain is maintained in contact
with steam until gelatinisation of the starch is effected, after
which it is passed to rollers which are internally heated by steam
or gas. The rollers are so adjusted that one roll travels faster
than the other, and in this manner the gelatinised starchy
material as it passes through becomes flaked.
The flakes are finally passed to another perforated cylinder,
enclosed with an iron casing, where they are kept in motion and
subjected to a circulation of hot air until perfectly dry.
In the manufacture of granulated material the methods
employed are similar, excepting that there is no necessity to pass
through rollers, as when manufacturing flakes. It is not unusual
to steep the material in an aqueous acid solution for some time
and then wash it until the washings are neutral, before steaming.
In the analysis of raw grain it sometimes becomes necessary to
estimate the percentage of starch, but so far as the brewer is
concerned, it is more usual to determine the extract yield.
PREPARED RAW GRAIN (GRANULATED AND FLAKED MAIZE
AND RICE).
The following are the determinations to be made :
1. Oil.
2. Starch.
3. Extract per quarter.
15
226
THE BREWER'S ANALYST
4. Proteids or albuminoids.
5. Acidity.
6. Mineral matter or ash.
7. Moisture.
1. Oil. This estimation is usually carried out by means of a
Soxhlet fat-extracting apparatus (fig. 73), which consists of a
water bath 16 cm. diameter, a con-
stant water-level arrangement, a
stand and burner, a metal ball con-
denser, a Soxhlet tube, and a dis-
tilling flask. The alcohol or ether,
used for extracting the oil, is heated
in the flask by means of the heated
water in the bath, the vapour rising-
through the Soxhlet tube and being
condensed falls back into the inner
tube, where the material to be
denuded of oil is placed, so extract-
ing the oil. The condensed solvent
slowly fills the extractor, rises to
the level of the upper inner syphon,
and then returns back again into
the flask, the process being con-
tinuous.
Care should be taken that there
is no leakage in any of the con-
nections or parts of the apparatus,
as the solvent, being very inflam-
mable, would immediately take fire
should any of its vapour come in
contact with a flame.
A loose plug of glass wool or
cotton wool (free from fat) is in-
serted in the bottom of the Soxhlet
tube, and on the top of this is placed the material to be experi-
mented upon. Preferably, however, the material is placed in a
thimble of bibulous paper (fig. 74) and the thimble with its
contents inserted in the Soxhlet tube.
With raw grain, 5 grams, previously freed from moisture and
ground to powder, are added to a thimble and placed in the
Soxhlet, Forty c.c. of alcohol, specific gravity 0'920, are now
added to the distilling flask and the whole Soxhlet apparatus
FIG. 73.
METHODS OF ANALYSIS
227
connected together. The distilling flask is now slowly heated by
the water in the bath, and the alcohol then syphons off from the
extractor; it will be found of the required specific gravity, viz.
0*900, whilst the temperature inside
the extractor varies from 95-104 F.
(35-40 C.). The extraction is carried
on for 5 hours, after which the thimble
is removed from the Soxhlet tube and
its contents transferred to a beaker. 1
The distilling flask is now discon-
nected and the alcoholic solution is
filtered through a filter paper into a
tared beaker, both the flask and paper
being washed with alcohol and the
washings also collected. The beaker
containing the filtrate is now placed
on the water bath and the alcohol
cautiously evaporated. The beaker
with its residue is then placed in the
drying oven for 1 hour, after which
it is cooled under the desiccator and
weighed, the drying, cooling, and weigh-
ing being repeated until the weight is
constant.
The calculation is then as follows :
Five grams of grain taken, the oil,
after extracting, evaporating, drying, cooling, and weighing
Weight of beaker + oil residue
Weight of beaker
100
17-282 grams.
17-120
162
162 x ^ 3*24 per cent, of oil.
u
2. Starch. For the estimation of starch in cereals and other
starch-containing vegetable substances, C. O'Sullivan's method 2
is, on the score of accuracy, by far the best which has been pro-
posed. It consists in first denuding the grain of oil by lengthy,
repeated decantation by the aid of solvents, then solubilising the
starch and afterwards converting it into maltose and dextrin by
1 The grain freed from oil is used in the next experiment for the estimation
of starch.
2 Jni. Chem. Soc. Trans., 1884, 1.
228 THE BREWER'S ANALYST
the aid of malt extract, calculating the starch from the conver-
sion products obtained from both cupric oxide and polarimetric
estimations. The method, however, is very tedious and requires
a great deal of time ; means had therefore to be taken to shorten
the operation, and this has been accomplished ' by extracting the
soluble substances in a Soxhlet apparatus (as in our previous
experiment) in the place of the ordinary process of washing by
decantation, and after converting the starch calculating the same
from the amount of maltose produced.
When starch is hydrolysed by active diastase under suitable
conditions, there is a well-defined resting-stage in the reaction
which closely approximates to the following equation :
10C 12 H 20 10 + 8H 2 = 8C 12 H 22 O n + C 12 H 20 10 .
Starch. Water. Maltose. Dextrin.
Thus 100 parts of starch yield 84'4 per cent, of maltose.
Hence it follows that, if the starch of raw grain is so converted
by diastase as to ensure its splitting up according to the above
reaction, a mere determination of maltose from its cupric reducing
power ought to give a direct measure of the original starch in the
material without the necessity of polarimetric observation. The
following method is therefore recommended :
Five grams of the grain, freed from moisture and denuded of
oil, as in our former experiment, are removed from the Soxhlet
apparatus and transferred to a beaker; 100 c.c. of distilled water
are added and the infusion gradually boiled for about 30 minutes,
adding water, a little at a time, to replace that lost by evaporation.
After cooling to 134'6 F. (57 C.), 10 c.c. of active malt extract 2
are added, and the conversion allowed to proceed for 1 hour.
The solution is then boiled, filtered into a 200 c.c. flask, the
residue well washed, and the volume made up to 200 c.c. at
60 F. (15'5 C.). The solution now contains the conversion
products from the starch of 5 grams of the grain, and the precise
amount of the maltose is ascertained from the cupric oxide
reducing power as follows :
Cupric Oxide Redwing Poiw r. This estimation is made
as described in malt-wort analysis, 10 c.c. of the solution being
added to 30 c.c. of Fehling's solution (15 c.c. copper sulphate
1 Trans. Guinness Research Laboratory, 1903, 1, 79-91.
2 The malt extract is prepared by weighing about 40 grams of malt, grind-
ing the same to powder, and adding to a stoppered bottle together with 150 c.c.
of distilled water. The infusion is set aside for about 1| hours, occasionally
shaking, and is then filtered bright.
METHODS OF ANALYSIS 229
and 15 c.c. alkaline tartrate) together with 50 c.c. of water,
and the determination carried through as explained. CuO ob-
tained = '335 gram. The same estimation is made with 10 c.c.
of the cold-water malt extract, so that correction may be made
for the same. CuO obtained = '152. Then -335 - '152 = '183 x
Fehling's factor 7435= -1360 x 20 = 2-720 maltose in 200 c.c. or
5 grams of grain, which again multiplied by 20 gives 54*40 per
cent, maltose.
The starch equivalent to this maltose is now estimated on the
assumption that 84'4 parts of maltose correspond to 100 parts of
starch ; hence - = 64'45 per cent, starch.
3. Extract per QuaPteP. The method of procedure in this
estimation is somewhat similar to that employed for the estima-
tion of starch, viz., it consists in saccharifying the starch of a
known quantity of the raw grain by the aid of malt extract.
Twenty grams of the grain are weighed, placed in a beaker
together with 120 c.c. of distilled water and 50 c.c. malt extract
at a temperature of 150 F. (65'5 C.). The beaker is then
placed on the water bath and the contents maintained at this
temperature for 1 hour. At the end of this time the mash is
transferred to a 200 c.c. flask, cooled, and made to mark at 60 F.
(15-5 C.) with distilled water.
The mixture is then thoroughly shaken, filtered bright, and
the specific gravity of the wort taken.
We have here the extract produced by the grain plus that due
to the cold-water extract, and a correction must therefore be
made for the latter. This is performed as follows :
Of the original cold-water extract 50 c.c. are taken, slowly
raised in temperature to 150 F. (65*5 C.), and maintained at
this temperature with occasional stirring during 1 hour. The
extract is then transferred to a 200 c.c. flask, cooled, and made
up to bulk at 60 F. (15'5 C.) with distilled water. After
thoroughly mixing, the solution is filtered bright and the specific
gravity taken. We have here the extract due to the cold-water
infusion. The gravity in our first experiment obtained from the
mash, less that in our second experiment obtained from the cold-
water extract, gives the gravity due to the grain. This gravity,
multiplied by 3-32, 1 gives the extract yielded by 336 Ibs. of the
grain or extract per quarter.
1 The grains obtained from 20 grams of granulated or flaked maize or rice
are assumed to occupy a volume of 2 '5 c.c. This being the case when the
mash is made up to 200 c.c., the liquid portion will have a volume of
230
THE BREWER S ANALYST
Formerly it was not unusual to determine the extract obtain-
able from prepared raw grain by mashing two-thirds of a malt of
known extract and one-third of the grain, calculating the extract
in the usual manner of the mixture of malt and raw grain.
Obviously the extract of the malt had to be determined with the
greatest accuracy, as any error would be multiplied in the calcula-
tion of the extract of the raw grain. To show what this error
might amount to, Baker 1 determined the extracts of flakes by
mashing in the first place equal quantities of maize and malt,
and in the second place maize, together with two-thirds its weight
of malt. Four experiments were conducted, in each case with the
same maize, but with malts the extracts of which were known,
but of different diastatic powers. The following table shows the
results :
Diastatic
Power of
Malt.
Extract per 336 Ibs. of
Maize when mashed
with an equal Weight of Malt.
Extract per 336 Ibs. of Maize
when mashed with
two-thirds its Weight of Malt.
40
Ibs.
106*50
Ibs.
106-4
34
102-40
103-2
25
100-25
103-3
12
97-64
99-17
These results indicate the very marked influence which the
diastatic power of the malt employed has on the yield of extract,
and they also show that when more or less highly cured malts are
used, the proportion of malt to maize in the laboratory mash is a
matter of importance, if comparative results are to be obtained.
Where such a process has been followed, the manipulator will
now entirely agree with Baker; but the method has long been
superseded by the diastatic process devised by O'Sullivan, and
already described, the accuracy of which has been recently con-
firmed, 2 the following table being given in proof thereof.
200- 2 '5 = 197 '5 c.c. The factor to convert a 10 per cent, solution into Ibs.
per quarter is 3 '36. As, however, the concentration of the liquid in the above
experiment is less, the factor must be altered in proportion. The calculation
is as follows :
(200 - 2-5) x 3 -36 =3 . 318 in d numbers 3-32.
200
1 The Brewers' Journal, 1905, 41, 186.
2 Jnl. Fed. List. Brewing, No. 5, vol. xi., 1905, 395, 398.
METHODS OF ANALYSIS
231
20 GRAMS OF FLAKBS AND 25 c.c. DIASTATIC SOLUTION.
Diastatic Power of Malt
from which the Diastatic
Solution was obtained.
28
34
65
Extract per 336 Ibs.
of Flakes.
. 102-2 Ibs.
. 102-2
102-2 ,
From these results it appears that the diastatic power of the
malt used is of little importance when working with cold-water
malt extract. The question arose, however, as to whether the
full yield of extract was given when employing this proportion
of diastatic solution. A second series of experiments was
therefore conducted to ascertain what differences resulted from
the use of varying amounts of cold-water extract. The following
are the results :
20 GRAMS OF FLAKES USED.
Diastatic Power of
Malt used.
Extract per 336 Ibs. of Flakes.
25 c.c. Diastase
Solution.
50 c.c. Diastase
Solution.
75 c.c. Diastase
Solution.
28
Ibs.
102-3
Ibs.
104-0
Ibs.
104-2
65
103-4
104-4
104-4
It will thus be seen that when using 50 c.c. of cold-water
extract an increase over the amount yielded by 25 c.c. is shown,
but that no further increase occurs when as much as 75 c.c. is
used, and when using 50 c.c. it does not matter whether the
malt has a diastatic power of as low as 28 or as high as 65 ;
hence 50 c.c. of cold-water malt extract is the proper quantity
to employ for 20 grams of material.
It will be noted by these experiments that, although on the
laboratory scale the details are such as to result in reliably
obtaining the full extract capable of being yielded by the raw
material, yet in practice the extract yield may fall short by as
much as 7 Ibs. per quarter, should the malt employed be of very
low diastatic power.
Under these circumstances it is sometimes of as much
importance to know what extract a definite proportion of raw
material will yield in practice, when mashed in conjunction with a
232
THE BREWER'S ANALYST
certain class of malt, as it is to know what extract can be
obtained analytically ; hence the remarks on p. 218.
4. Proteids or Albuminoids Total Albuminoids.
These are determined by Kjeldahl's method, as explained for total
albuminoids under Malt Analysis (p. 207).
Soluble Albuminoids. Twenty grams of the grain, ground
to powder, are digested for 1J hours in 200 c.c. of distilled water
at a temperature of 120 F. (48*8 C.), with occasional stirring.
The infusion is then cooled to 60 F. (15*5 C.) and filtered =
10 per cent, solution. Fifty c.c. of the filtrate are now evaporated
to dryness and the determination conducted as explained with
soluble albuminoids in Malt-wort Analysis (p. 208).
Insoluble Albuminoids. Difference between total and
soluble albuminoids.
5. Acidity. This is determined by titrating 50 c.c. of the
10 per cent, cold-water infusion as used for the estimation of
soluble albuminoids with sodic hydrate, using litmus as
indicator.
N
c.c. alkali used x '009 x 10 = per cent, acidity on the grain.
6. Mineral Matter OP Ash. Determined from 50 c.c. of the
10 per cent, cold-water extract as employed for the determination
of soluble albuminoids just described, and conducted as explained
under Malt Analysis (p. 204).
7. Moisture. Determined on 5 grams of the material, as
explained under Malt Analysis (p. 201).
ANALYSIS OF PREPARED EAW GRAIN (GRANULATED AND FLAKED
MAIZE AND RICE), CONDUCTED ACCORDING TO THE PRECEDING
INSTRUCTIONS, GAVE THE FOLLOWING :
Granulated.
Flaked.
Maize.
Rice.
Maize.
Rice.
Oil.
Extract per quarter (336 Ibs. )
,, per cent.
Total proteids or albuminoids
Soluble
Insoluble ,, ,,
Mineral matter or ash
Moisture . ...
0-98
98-44
75-90
9-20
0-62
8-58
0-30
1072
0-76
102-48
79-01
874
0-41
7-33
0-26
7'83
0-97
98-78
76-16
9-50
0-34
9-20
0-44
6-30
0-29
10315
79-53
8-53
28
8'25
0-32
7-43
METHODS OF ANALYSIS
233
ANALYSIS OF UNPREPARED RAW GRAIN (RAW MAIZE GRITS
AND RAW RICE).
The determinations to be made are exactly the same as with
the preceding prepared granulated and flaked maize or rice, and
are carried out in precisely the same manner, excepting that in
the determination of extract it becomes necessary to gelatinise
and cool the starch before adding the malt extract.
Twenty grams of the ground grain are placed in a beaker
together with 120 c.c. of distilled water and gradually boiled for
about 30 minutes, adding water, a little at a time, to replace
that lost by evaporation. The solution is then cooled to 150 F.
(65 '5 C.), 50 c.c. of malt extract added, and the operation carried
on as described, from this point, with prepared raw grain
(p. 229).
ANALYSIS OF UNPREPARED RAW GRAIN (RAW MAIZE GRITS AND
RAW RICE), CONDUCTED ACCORDING TO THE PRECEDING
INSTRUCTIONS, GAVE THE FOLLOWING :
Unprepared
Unprepared
Raw Maize Grits.
Raw Rice.
Starch .
6438
78-20
Oil
3'25
0-21
Extract per quarter (336 Ibs.)
Total proteids or albuminoids
99-50
9-00
106-00
7-73
Soluble
0-50
0-33
Insoluble ,, ,,
8-50
7-40
Mineral matter or ash
2-20
1-54
Moisture ....
870
10-92
Cellulose, gums, etc., by difference
12-47
1-40
ANALYSIS OF BLACK, BROWN, AMBER, AND CRYSTAL MALTS.
These materials are analysed in precisely the same manner as
prepared raw grain (granulated or flaked maize or rice).
We have, however, to alter the factor by which to multiply the
excess gravity between the mash and cold-water extract. The
average bulk occupied by the grains from 20 grams of any of
these malts is 6 c.c. ; the factor to multiply the excess gravity
between that of the malt and cold-water extract, calculated on
the basis shown in the footnote, p. 203, is therefore 3'26. Hence
in the determination of extract, specific gravity, minus 1000,
multiplied by 3'26, gives Ibs per quarter (336 Ibs). There is one
234
THE BREWER S ANALYST
other point, viz., with regard to black malt, it is often required
to test its colour value. This is best performed by examining a
'01 per cent, boiled and cooled solution in a 1-inch cell of
Lovibond's tintometer. One gram of the malt is weighed, ground
to powder, and boiled in about 200 c.c. of distilled water for 15
minutes, afterwards cooled and made up to 1 litre *= '01 per cent,
solution.
ANALYSES OP BLACK, BROWN, AMBER, AND CRYSTAL MALTS,
CONDUCTED ACCORDING TO THE PRECEDING INSTRUCTIONS,
GAVB THE FOLLOWING :
Black.
Brown.
Amber.
Crystal.
Extract per quarter (336 Ibs. )
57-75
57-12
84-53
58-26
,, per cent. .
44-30
44-04
65-02
45-07
Acidity of wort
29
23
19
17
Total proteids or albuminoids
6-11
7-13
7-62
8-71
Soluble
2-12
2-32
1-93
2-83
Insoluble ,, ,,
3-99
4-81
5-69
5'88
Mineral matter or ash
32
29
1-20
76
Moisture
5-37
6-23
4-14
2-12
BARLEY ANALYSIS.
It is not often that the analyst is submitted samples of barley
and asked to judge quality and give chemical analysis of the same,
yet the importance of analytical results are now being realised.
The following are the determinations to be made :
1. Extraneous matters.
2. Defective corns.
3. Weight per bushel.
4. Steely corns.
5. Character of endosperm.
6. Vegetative energy and capacity.
7. Oil.
8. Starch.
9. Proteids or albuminoids.
10. Mineral matter or ash.
11. Moisture.
1. Extraneous Matters. Determined as with Malt (p. 190).
2. Defective COPnS. These include those corns which are
broken, crushed, mouldy, damaged in dressing or by insects,
METHODS OF ANALYSIS 235
weathered in field, sprouted, heated in stack or very minute in
size.
Five hundred corns are taken promiscuously from the sample
and the percentages calculated.
3.' Weight per Bushel. As per Malt (p. 191).
4. Steely Corns. As per Malt (p. 191).
5. Character Of Endosperm. Obviously, if barley will
not germinate, vegetate, or grow, it is impossible to convert it
into malt. Hence vitality of the germ is one of the most
essential conditions of good barley, since should any sample
possess more than an extremely small percentage of the grain
incapable of germinating, there is con-
siderable loss, as all ungerminated corns
represent merely so much raw barley
in the finished malt, and apart from
yielding merely an infinitesimal extract
at the mashing stage, form breeding-
grounds for mould during vegetation
on the malt-house floor, and result in
the diastatic power of the malt being
low.
Defective vitality may arise from
under- or over-ripeness, incipient ger-
mination in the ear owing to a wet p IGi 75.
harvest, death of the germ through
heating in the stack, or improper storage, the attacks of insects
and vermin, or damage to the grain during threshing.
The best test for vitality is to grow a sample of the barley ; but
this takes time, and the practical man, purchasing as he does in
the open market, is therefore unable to avail himself of this
method of procedure.
The test is usually carried out by taking 100 corns pro-
miscuously from the sample without any picking or choosing,
and placing them in an apparatus known as Coldew's germinator
(fig. 75). It consists of a glass vessel with a constriction about
1J inches from the top, on which rests a porcelain plate provided
with 100 perforations. Into each of these a corn of barley is
inserted with the germ end downwards. The apparatus is nearly
filled with water, the plate inserted, a small quantity of sand
placed on top of the barley, and this is then moistened with water.
A wooden cover with a layer of felt is then placed over the sand,
and a small thermometer attached to the cover serves to indicate
the temperature at which the experiment is being conducted. Upon
236 THE BREWER'S ANALYST
allowing germination to proceed for a few days, the relative
degrees of vitality of the different corns can be readily estimated,
and the number of sluggish and dead corns seen at a glance.
6. Vegetative Energy and Capacity. According to the
percentage of grain in a sample of barley which, when placed
under favourable conditions for germination, vegetate within a
definite time (this at the ordinary temperature being generally
taken as 3 days), so is the vegetative energy; whilst the
term vegetative capacity is employed to express the
percentage number of corns which are found capable of germinat-
ing irrespective of time.
In a good sample of barley the vegetative energy should be not
less than 90 per cent., and the capacity not below 95 per cent.
The more closely these two characters correspond, the better,
since any great variation plainly indicates that the sample would
grow irregularly during malting.
7. Oil. Determined as per Raw Grain (p. 226), 5 grams being
taken and the extraction in a Soxhlet apparatus conducted for
5 hours.
8. Starch. As per Raw Grain (p. 227).
9. Proteids or Albuminoids. As per Malt (p. 205), 5
grams being taken, ground to powder, and treated according to
KjeldahPs method.
10. Mineral Matter or Ash. As per Raw Grain (p. 232).
11. Moisture. As per Malt (p. 201), 5 grams of the finely
ground material being dried for 3 hours in the water oven.
HOP ANALYSIS.
The following are the determinations to be made :
1. Extraneous matters.
2. Soft and hard resins.
3. Tannin.
4. Moisture.
5. Sulphur.
1. Extraneous Matters. A fair sample of the hops should
be taken by opening the pocket or bale and taking a piece from
the middle. This should include both the outside and interior of
the hops. A flake should then be selected right across the hops
so as to include as near as possible a portion of the outside and
inside of the sample. The flake may be about 5 grams weight,
and, without breaking it up, its exact weight should at once be
ascertained. Say, for example, we select exactly 5 grams. This
METHODS OF ANALYSIS 237
sample is now placed on a piece of white glazed paper, and, by
means of forceps, separated. Such a sample will be found to
contain leaves, stalks, etc. ; and these are then separated as
accurately as possible and,, weighed, the amount so found being
expressed as extraneous matters.
2. Soft and Hard Resins. Having separated the extraneous
bodies from the sample, as in the former experiment, and ascer-
tained the weight of the same, the hops, which in this instance,
including their moisture content, which must hereafter be reckoned
with, weigh, say, exactly 4'5 grams. They are now transferred
to a Soxhlet oil-extracting apparatus (fig. 73, p. 226) ; l 120 c.c.
of petroleum ether is now added to the distilling flask, and the
whole connected as shown in the figure. A light is now placed
under the water bath and the temperature raised and maintained
by the thermostat at a temperature of 155 F. (68*3 C.), which
causes the ether to circulate continuously through the hops. The
extraction, which proceeds slowly, is carried on for about 24 hours,
the flask being then disconnected from the apparatus, its contents
being filtered, whilst hot, through a small filter paper into a tared,
wide-mouthed flask, and the filter paper being thoroughly washed
with petroleum ether and the washings also collected.
The filtrate is now gently evaporated over the water bath, the
soft resins being left as a residue. The flask is now placed on its
side in the water oven, where it is maintained at a higher tempera-
ture than the boiling-point of ether, so that all traces of ether
are got rid of. The flask is now placed under the desiccator
and when cool weighed, the drying, cooling, and weighing being
repeated until the weight is constant.
In the meantime the hops in the Soxhlet apparatus are further
extracted by placing 120 c.c. of ordinary ether in the original
flask, again connected with the apparatus, and the flask heated as
before, excepting that the water in the bath is reduced in tempera-
ture to 135 F. (57 '2 C.), and the circulation of ether carried on
for a further 12 hours. The ethereal extract of the hard resins is
thus obtained, filtered through the paper previously employed for
the soft resins, washed with ether, and the evaporation and drying
carried on as before. The analysis of both extracts is carried on
in duplicate, and the mean of the results expressed in percentage
on the dry hops, thus :
Of the 4'5 grams of hops originally taken, we have to make a
1 Instead of adding the hops direct to the Soxhlet tube, they are preferably
placed in a thimble of bibulous paper (fig. 74, p. 227), this and its contents
being placed in the Soxhlet apparatus.
238 THE BREWER'S ANALYST
correction for moisture, and as this is found (p. 242) to equal
9 per cent., the 4'5 grams contain 0*4, so that the actual hops used
in our experiment equal 4'1 grams.
On extraction with petroleum ether the weight equalled 0-439
i no
gram of soft resins, therefore '439 x = 10'70 per cent.
preservative soft resins.
After extraction with sulphuric ether the resins obtained
equalled 0'136 gram, so -136x^=3-03 per cent, non-
preservative hard resins.
Heron points out that it is exceedingly difficult to dry the
residues from the ethereal extracts, and considers that a more
reliable method for determining resins in hops is, instead of
weighing the residues from the extracts, to weigh the hops from
which the resins have been extracted. The author supports this
opinion; but such method undoubtedly prolongs an already
lengthy process, and gives results which are so infinitesimal as
to hardly warrant its adoption.
3. Tannin. The estimation of tannin in hops and various
other astringent materials is not of the most satisfactory char-
acter. A great variety of methods have been proposed, the best
of which appears to be the gelatine process as modified by Mulder,
and the process by Lowenthal, modified by Neubauer.
The latter method is the one now generally employed, and has
been worked out as satisfactorily as possible by Heron. 1
It consists in titrating an aqueous hop extract with a weak
standard solution of potassic permanganate, both before and after
the removal of the tannin, by means of gelatine, using indigo solu-
tion as indicator.
Tannin is a very readily oxidisable substance, and its amount
may be measured by the quantity of an oxidising agent, such as
permanganate, taken to effect its oxidation. The addition of indigo
is merely to act as an indicator, the indigo itself being readily
oxidised into the so called " white indigo." Its affinity for oxygen
is, however, less than that of tannin, so that we are aware, when
it has been decolorised, that all the tannin has been oxidised.
The indigo has then to be similarly titrated with permanganate
and the addition of sulphuric acid ; but without the aqueous hop
extract, and upon determining the amount of permanganate which
the indigo consumes, we deduct this from the total used in our
first experiment.
1 Jnl. Fed. lust. Brewing, 1896, 165.
METHODS OF ANALYSIS 239
We have not yet, however, a direct indication of the amount of
tannic acid present in the solution, because there are other bodies
present which also have an affinity for oxygen, and therefore
reduce permanganate ; we Jiave therefore to ascertain the extent
of reduction effected by these bodies before we arrive at the real
amount of tannin present. We cannot well precipitate or remove
these bodies from the solution, but as an alternative we may effect
the separation of the tannin, and, by noting the difference in
reduction, deduce from this its amount. This we accomplish by
the well-known power which gelatine possesses of precipitating
tannin from its solution, and we proceed, according to Heron,
as follows :
ESTIMATION OP TANNIN IN HOPS.
Ten grams of the hops are weighed out carefully and introduced
into a wide-mouthed boiling flask graduated to 1005 c.c. and
containing 900 c.c. of boiling distilled water.
The flask is then plunged into a bath of boiling water and
digested under these conditions for 1 hour, shaking it occasion-
ally during the digestion.
It is then taken out, cooled down to 60 F. (15-5 C.), and
distilled water is added until the liquid in the flask reaches the
containing mark ; the flask and contents are then well shaken,
and the extract so obtained is filtered as bright as possible.
As a rule it is difficult to get the infusion to filter bright, but
the addition of a little kaolin facilitates the brightening of the
filtrate to a marked degree.
One hundred c.c. of the filtrate represent the extract obtained
from 1 gram of hops ; the liquid is made up to 1005 c.c. instead of
1000 c.c., because it is found, as the mean of several experiments,
that the volume occupied by 10 grams of hops, when completely
exhausted, equals 5 c.c. ; or, the 10 grams of hops may be weighed
out in a tared beaker, digested in a water bath of boiling water
with 1000 c.c. of distilled water for 1 hour, cooled down to 60 F.
(15'5 C.) and then weighed, adding distilled water, if necessary,
until the weight equals 1010 grams plus the tare of the beaker.
By this digestive process a complete extraction of the tannin is
made in 1 hour.
It is advisable to see that in making the extract the water is
actually boiling, for by working in this way the results are more
uniform.
The extract of hops having been obtained, the next point is the
determination of the tannin contained therein.
240 THE BREWER'S ANALYST
In order to perform this, the three standard solutions, viz.,
potassic permanganate (p. 144), indigo, and gelatine, detailed
respectively on p. 145, are required, as well as a solution of
sulphuric acid (50 grams concentrated sulphuric acid diluted with
distilled water to 1 litre).
Fifty c.c. of the hop infusion are introduced into a shallow
white porcelain dish of about 1 litre capacity, 20 c.c. indigo
solution added, and 500 c.c. of good water ; the permanganate
solution is then added from a graduated burette in a rapid
succession of drops, the liquid in the basin being kept vigorously
stirred all the time with a glass rod : towards the end of the
reaction the blue colour produced by the indigo changes to a
light yellowish-green, rapidly changing into a golden yellow.
The titration is finished when this yellow colour is produced.
When the distinctly blue colour begins to disappear, the perman-
ganate must be run in more slowly and added very cautiously.
Two such determinations should be made, and the mean of them
taken, the number of c.c. of permanganate required for the 20 c.c.
of indigo solution subtracted, and the remainder, multiplied by
2, represents the amount of total oxidisable bodies in 100 c.c. of
the hop extract. Let this be denoted by a.
In order to determine the amount of permanganate required
by the indigo solution, 20 c.c. of indigo solution should be added
to 500 c.c. of water, and then the permanganate run in as
already described.
One hundred c.c. of hop infusion are next taken and carefully
poured into a wide-mouthed, 16 oz. flask, 100 c.c. of gelatine
solution are added, the mixture in the flask well shaken, then
50 c.c. of the dilute sulphuric acid added, the flask shaken as be-
fore, then a teaspoonful of kaolin added, and the contents of the
flask thoroughly well shaken once more, after which filtration
may at once be proceeded with.
One hundred c.c. of the filtrate are introduced into the porcelain
dish along with 20 c.c. of indigo solution and 50 c.c. of water,
and the titration with permanganate proceeded with as before.
The mean of two experiments, less the amount of permanganate
required for the indigo, multiplied by 2 '5, represents the amount
of oxidisable bodies in 100 c.c. of the extract after the tannin
has been removed ; denote this by b. Then a - b will equal the
number of c.c. of permanganate required to oxidise the tannin
in 100 c.c. of the extract.
Now, if we know the exact amount of hop tannin which 1 c.c.
of permanganate is equal to, it will be very easy to calculate
METHODS OF ANALYSIS 241
the percentage of tannin present in the hops. It is true, Hayduck
states, that 1 c.c. of permanganate is equivalent to, or oxidises,
0002026 gram tannin, presumably hop tannin; but as this is
a very much higher number than the one given by Neubauer
for oak tannin several years ago, Heron does not care to adopt it
without further confirmation.
Under these circumstances he considers the best plan is to
express the number of cubic centimetres of permanganate re-
quired to oxidise the hop tannin in terms of oxalic acid, a
standard which is easily and exactly verified; and certainly,
for general purposes, that is, for the determination of tannin
in substances other than hops, it is imperative that such
a standard should be used. It is well known now that the
tannins derived from different sources differ very much in many
of their properties, and give different values when acted on with
potassium permanganate ; so that not until these different tannins
have been isolated in a state of purity, and their values determined
in terms of permanganate, can we determine with any degree of
confidence or accuracy the exact amount of tannin in the sub-
stance under examination. Now we can measure exactly the
amount of permanganate by means of oxalic acid, so that all
our results by this method are strictly comparable for each
individual tannin-containing substance. If therefore c be the
N
quantity of permanganate required to oxidise 10 c.c. of oxalic
acid, and 10 grams of hops have been employed in making 1000 c.c.
of extract a ~ = z, where x is the percentage of tannin
c
expressed in terms of pure oxalic acid.
Sometimes the gelatine solution has a very slight reducing
action itself on the permanganate, so that it is advisable to make
a blank experiment with each freshly made-up lot of gelatine
solution; and where it is found that it possesses any reducing
action, due correction for this must be made.
It is also a good plan, at starting a titration, to use the first
experiment as a standard colour test for the succeeding ones.
The following example will serve to illustrate the working of
the process :
50 o.c. infusion ) ^ ^ ^ anate .
20 indigo solution j
20 alone required 20'25
10-65
16
242 THE BREWER'S ANALYST
Total oxidisable bodies
100 c.c. in hop extract, required 10-65 x 2 = 21*30 c.c. = a.
After precipitation with gelatine
100 c.c. nitrate )
OA . j. , ,. ; required . 24'/ c.c. permanganate.
20 ,, indigo solution )
20 alone required 20'25
4-45
Correction for gelatine . . 1 '95
2-50
Oxidisable non-tannin bodies > = 2 . g QQ x 2 .5 = 6>25 c c = ^
in 100 c.c. hop extract
Hence a = 21 '30
b= 6-25
c = 31-6,
and according to the formula
21-30 -6-25 = 15-05,
15-05x6-3 Q An
and = 3'00 per cent, tannin ex-
o 1 *o
pressed in terms of oxalic acid.
4. Moisture. This is determined by drying a convenient
weight of the hops in the water oven, or preferably over sulphuric
acid in vacuo, for 3 hours or longer, until the weight is constant.
The main proportion, if not all, of the oil is driven off by this
process; but as it does not exceed 0*5 per cent., the error this
involves is not great, whilst if necessary a correction for this
may be made.
Example. 5"211 grams of hops dried in the water oven for 3
hours, cooled under the desiccator, and weighed.
Loss in weight = 0*4 70 gram.
^g^ = 9 per cent, moisture.
5. SulphllP. Sulphur may be readily detected in hops by
generating hydrogen in contact with them and examining the
escaping gas for sulphuretted hydrogen, very small quantities
of which may be detected either by its offensive smell of rotten
eggs, or by the production of a black coloration when allowed to
impinge upon paper moistened with a solution of lead acetate, or
come in contact with a solution of the same.
METHODS OF ANALYSIS 243
A convenient method of conducting this test is to generate
hydrogen from zinc and dilute sulphuric acid in a small bottle
containing about 200 c.c. of water and fitted with a cork, through
which passes a bent tube to. conduct the gas from the generating
bottle into a small beaker containing a little lead acetate
solution. (The Tyrer-Marsh apparatus, fig. 78, p. 274, is best
employed for the generation of the gas.) After the gas has
been allowed to pass for a short time, if the materials are pure,
no change will take place in the lead solution. This being
proved, the cork is removed from the bottle and a few hops,
together with a little potash lye, are added, the cork being
immediately replaced. If the hops contain sulphur, the nascent
hydrogen will combine with it, producing sulphuretted hydrogen
(SH 2 ) which passes into the lead solution, revealing its presence
by the production of a black precipitate of lead sulphide, thus :
Provided sulphur is detected as above described, the experi-
ment is repeated, using 10 or more grams of hops and passing
the sulphuretted hydrogen fumes into a definite quantity of
lead acetate. The precipitated lead sulphide is then filtered,
washed, dried, ignited, cooled and weighed, the sulphur being
calculated from the weight so found. One part of lead sulphide
(PbS) = 0-1345 sulphur.
An analysis conducted according to the foregoing instructions
gave the following :
MID-KENT HOPS.
Preservative soft resins . . . 10'70 per cent.
Non-preservative hard resins . . 3'03
Tannin . 3 '00
Moisture ..... 9 '00
Sulphur ..... Nil.
BEER ANALYSIS.
The following are the determinations to be made :
1. Original gravity.
2. Present gravity.
3. Dry extract.
4. Alcohol.
5. Acidity.
244 THE BREWEK'S ANALYST
6. Specific rotatory power.
7. Colour.
8. Proteids or albuminoids.
9. Mineral matter or ash.
10. Iron.
11. Salicylic acid.
12. Malto-dextrins, etc.
Fermented matter.
Low-type malto-dextrins.
Combined maltose.
Combined dextrin.
Free dextrin.
Unfermentable reducing residue.
13. Brilliancy.
1. Original Gravity. The specific gravity of a wort, as
determined by the brewer by the aid of a saccharometer, when
about to . enter the collection upon which the duty is to be
charged, that is to say, before fermentation has commenced, is
known as the original gravity. In course of time the wort
ferments, the yeast organism splits up or decomposes sugar or
fermentable bodies which results in the formation, as chief
products, of alcohol and carbonic acid, the former remaining in
the liquid (excepting a small proportion which is carried off
mechanically with the carbonic acid gas which is largely evolved)
and from its low specific gravity diminishing the specific gravity
of the liquid. The original specific gravity of the wort is thus
lowered during fermentation ; but according to the lowering of
the specific gravity, so are other bodies in fairly definite proportion
formed. From every 100 parts of sugar decomposed, 52 parts of
alcohol and 48 parts of carbonic acid, with traces of other bodies
such as succinic acid, glycerin, etc., are produced ; hence if we
remove the alcohol from a definite quantity of beer, and make up
the beer to the same bulk as before with distilled water, we
shall be able to ascertain the specific gravity of the liquid minus
alcohol ; or, in other words, of the matter still remaining ' as
unfermented extract in the beer ; and by ascertaining the specific
gravity of the separated alcohol, we may find how much
fermented extract it represents, since, as before stated, every
100 parts of the extract have produced fairly definite quantities
of other substances.
From these two factors we therefore arrive at the original gravity.
There are several methods' for determining the original gravity
METHODS OF ANALYSIS
245
of beer, but the " distillation process " is the best and most
reliable, and is the one adopted in the analytical department of
the Board of Inland Revenue. The various methods have been
carefully investigated by Graham, Hoffmann, and Redwood, and
from their observations the following table has been drawn up and
adopted.
SPIRIT INDICATION, WITH CORRESPONDING DEGREE OF GRAVITY
LOST IN MALT WORTS BY THE "DISTILLATION PROCESS."
~9 ~
Degree
of
Spirit
o
1
2
3
4
5
6
7
8
9
Indi-
cation.
o-o
3
6
9
1-2
1-5
1-8
2-1
2'4
27
1
3-0
3-3
37
4-1
4'4
4'8 51
5-5
5'9
6'2
2
6-6
7-0
7-4
7-8
8-2
8'6
9'0
9'4
9'8
10-2
3
107
11-1
11-5
12-0
12-4
12-9
13-3
13-8
14-2
14 7
4
15-1
15-5
16-0
16'4
16-8
17-3
177
18'2
18'6
191
5
19-5
19'9
20-4
20-9
21-3
21-8
22-2
227
23-1
23'6
6
24-1
24-6
25-0
25-5
26-0
26-4
26'9
27-4
27-8
28-3
7
28-8
29'2
297
30-2
307
31-2
317
32-2
327
33-2
8
337
34-3
34-8
35-4
35-9
36-5
37-0
37 5
38-0
38-6
9
39'1
397
40-2
407
41-2
417
42-2
427
43-2
437
10
44-2
447
45-1
45-6
46-0
46-5
47'0
47-5
48-0
48'5
11
49-0
49-6
50-1
50-6
51-2
517
52-2
527
53-3
53-8
12
54-3
54'9
55'4
55-9
56-4
56-9
57-4
57'9
58'4
58-9
13
59-4
60'0
60-5
61-1
61-6
62-2
627
63-3
63-8
64-3
14
64'8
65-4
65-9
66'5
67'1
67-6
68-2
687
69-3
69-9
15
70-5
71'1
717
72'3
72-9
73-5
74'1
747
75-3
75-9
16
76-5
The details of the distillation process are as follows :
A 200 c.c. flask is filled to the mark with the beer at a
temperature of 60 F. (15 '5 C.). If the beer is flat, this is easily
accomplished; if, however, the beer is in much condition it is
necessary to filter it through a dry filter paper into a dry beaker
in order to expel the gas and measure the beer with accuracy.
The expulsion of the gas is advantageous also from the fact that
during distillation frothing is not likely to take place as it other-
wise would. Instead of filtering the beer, the same object may
be brought about by pouring it from one beaker to another.
Having accurately measured 200 c.c. of the beer at 60 F.
(15*5 C.), it is transferred to a capacious distilling flask, the 200
c.c. flask is then washed out with a little distilled water, and the
washings added to the beer ; the flask containing the beer is then
246 THE BREWER'S ANALYST
connected to the still apparatus (fig. 33 or 34, pp. 29-30), a flame
is placed beneath, the^condensing water turned on, and distillation
commenced.
The distillate is collected in the 200 c.c. flask originally used in
measuring the beer, and the distillation continued until about
two- thirds of the liquid has passed over, when the process is
stopped and the flask removed.
The spirit has now been all expelled from the beer in the boiling
flask, and is contained together with water in the distillate,
whilst the liquid left in the boiling flask is now known as the
residue.
To estimate the amount and value of the spirit, the contents
of the 200 c.c. flask are now made up with distilled water to the
original bulk (200 c.c.) at 60 F. (15-5 C.), thoroughly agitated,
and the specific gravity taken by means of the specific gravity
bottle.
The actual specific gravity, compared with the weight of water
(1000), is then deducted from that number, and this result is
termed the " spirit indication." From this indication the amount
of decomposed or fermented extract is calculated. Thus if the
specific gravity of the spirit has been found to be 991- 5, 1 then the
spirit indication would be
1000-991-5 = 8-5.
By referring to the table previously shown, we find that
8*5 = 36*5 degrees of gravity lost during fermentation.
We have now to ascertain the value of the extract still remain-
ing unattenuated in the beer, viz., the " residue/' In order to do
this the residue in the boiling flask is transferred to the 200 c.c.
flask, the boiling flask repeatedly rinsed out with distilled water,
and the washings added to the 200 c.c. flask. The liquid is then
cooled and finally made up. at 60 F. (15*5 C.) to 200 c.c. with
distilled water and the specific gravity taken as with the spirit.
Assuming this is found to be 1024*0, the original gravity of the
beer would be
Degrees fermented . . . . 30 '5
Degrees unfermented . . 1024-0
1060-5
degrees, which expressed in Ibs. per barrel = 60'5 x *36 = 21 '78 Ibs.
per barrel.
1 The present gravity (1015*5), minus this figure (991 '5), should equal the
gravity of residue (1024'0), which in this case it does.
METHODS OF ANALYSIS 24?
In determining the original gravity of beers containing over
0*10 per cent, of acidity, a correction must be made as described
under Acidity.
It should also be remembered that the original gravity of a
beer, as determined by analysis and calculated by table, is always
below that of the unfermented wort, the difference usually
amounting to about 2 degrees.
2. Present Gravity. The present gravity of beer should
always be determined when testing the original gravity, since it
shows to what extent the beer has attentuated, and serves as a
check upon the result, thus :
Let us assume that by the specific-gravity bottle we find the
specific gravity of the beer to be 1015*3.
Now, as we have already determined the specific gravity of the
alcohol, we have merely to deduct the " spirit indication " from
the weight of the residue, to obtain the present gravity of the
beer. Thus :
Specific gravity of residue already found . . 1024*0
Spirit indication . . . . . 8*5
Present gravity . . . 1015*5
while a direct experiment with the specific-gravity bottle gave
1015*3, thus corroborating the results within 0*2 degree, which is
generally the difference between calculated and observed present
gravities.
Original Gravity as determined by the Alcoholmeter.
To obviate the tedious and laborious methods of determining
the original gravity of beer by the evaporation or distillation
methods, an instrument was devised years ago by Field, and
named by him the "alcoholmeter." This instrument has lately
been improved upon by Manley, and gives fairly accurate results.
The previously mentioned distillation process, however, should be
carried out in all cases where extreme accuracy is desired although
it must be remembered that the original gravity determination is
of little use by itself, it being necessary to test the carbohydrate
constituents in a beer before a general opinion of its character
can be expressed.
The principle of Field's or Manley's alcoholmeter consists in
the fact that all spirituous liquors boil at a lower temperature than
water, so that the larger the quantity of alcohol in any beer the
lower will be its boiling-point. Hence by determining the
boiling-point of water which, it must be recollected, varies a
248
THE BREWER'S ANALYST
degree or two daily according to barometric pressure and after-
wards determining the boiling-point of the beer under examination,
the carbohydrate substances, which must have been present in
the wort and have been hydrolysed to alcohol, are estimated and
the original gravity of the beer determined.
To save any complicated tables or calculations the alcoholmeter
is fitted with a scale showing specific gravity degrees to 95,
divided into tenths for the purpose hereafter explained.
The instrument, a sketch of which is shown (fig. 76), consists of
a small boiler (c) into which is poured about 120 c.c. of water or
beer, and boiled by a small spirit-lamp placed
underneath. The boiler is closed by placing
on the cap which carries a mercurial glass
tube the bulb of which dips into the liquid
in the boiler, the remainder of the tube
being continued, and by the side of which is
arranged the scale (B) showing specific gravity
degrees. The scale is rendered movable by
the turning of the screw shown at the top of
the instrument. By the side of the mercurial
tube and scale is a small cylinder (A) with
an open tube passing through it and through
the lid.
About the same quantity of cold water is
added to this cylinder (which acts as the
condenser) as beer or other liquid placed in
the boiler, so that when a spirituous liquor is
being boiled, the evolved alcohol is condensed
and drops back into the boiler through the
open tube.
In conducting a specific gravity determina-
tion we proceed as follows :
Example. About 120 c.c. of cold water is placed in the boiler,
the same quantity added to the top cylinder, the lamp lighted
and the water boiled. The mercury rises to almost the top of
the tube, and when constant the scale is adjusted by the top
screw so as to fix the boiling-point of water for some hours at
least during the day. The water is then emptied out of both the
boiler and the condensing cylinder, about 120 c.c. beer added to
the boiler and the same quantity of cold water to the cylinder,
and the boiling continued. The mercury then rises to a certain
height, according to the quantity of alcohol present in the beer,
and according to the height so is the degree read off from the
FIG. 76.
METHODS OF ANALYSIS 249
graduated scale. Say, for example, the scale having been set to
(zero) from the boiling-point of water, the mercury now rises to
55 from the boiling of the beer ; the specific gravity of the beer
as due to the alcoholmefeer is therefore 55, which, added to the
present gravity of the beer, determined by a small saccharometer
supplied with the instrument, shows at once the original gravity.
Thus alcoholmeter 55 and present gravity 1010=1065 original
gravity.
3. Dry Extract. This is ascertained from the specific gravity
of the imfermented extract or residue obtained when determining
the original gravity. It is useful in the sense that from it the
constituents in the un fermented extract may be expressed on the
dry solids, thus establishing a means of comparison between the
solid matter in beers of different gravities and degrees of
attenuation.
It may be determined by evaporating a definite bulk of beer to
dryness in a tared platinum dish till the weight is constant and
then calculating into terms of 100 c.c. During the evaporation,
however, several of the constituents of the beer are oxidised, and
the results are by no means satisfactory (see Solution Factor, p. 57),
hence for all ordinary purposes it is more usual to employ the
solution factor 3 '86 ; thus
Specific gravity of residue was found to be . 1024*00
Weight of water 1000 '00
24-00
24-00 -r 3-86 = 6'21 per cent, dry extract
4. Alcohol. From the specific gravity of the spirit the per
cent, of absolute alcohol by weight and the per cent, of proof
spirit is ascertained by reference to the following table :
[TABLE.
250
THE BREWER'S ANALYST
ALCOHOL TABLE.
,
3
,
"o
>>
"3
'>
8 . 4-5
*O -tn
'
o
'o tij
'>
"o ^_-
*o .t2
^0
S GO
|
^ "S'Sc
|||
|2
^ g3J>
0) O
if
f
1 *
11
r
| ^
l|
1*
1 ^
GO
5
00
2
CO
^
995*0
274
6*02
992-8
4-02
8*81
990*6
5*39
11*79
994-9
2-79
6*13
992-7
4-08
8-94
990-5
5*45
11*92
994*8
2-85
6*26
992-6
4-14
9-07
990*4
5-51
12-05
994-7
2-91
6-39
992-5
4-20
9-20
990*3
5*58
12-20
994-6
2-97
6*52
992-4
4-27
9-36
990-2
5*64
12-33
994-5
3-02 6-63
992-3
4'33
9-49
990-1
570
12-46
994-4
3-08
6*76
992-2
4*39
9-62
990*0
577
12-61
994-3
3-14
6*89
992-1
4*45
9-75
i
994*2
3-20
7*02
992-0
4*51
9-88
989*9
5-83
12*74
QQ4*1
3 .of;
*7 *1 f\
989*8
5*88
12'87
y 7rr 1
994*0
^O
3-32
7-29
991-9
4*57
10-01
989*7
5*96
13-02
991*8
4*64
10*16
989*6
6'02
13*15
993-9
3-37
7*40
991-7
4*70
10*29
989-5
6-09
13-30
993-8
3-43
7-53
991*6
4-76
10-42
989-4
615
13*43
993-7
3-49
7-66
991-5
4-82
10-55
989-3
6-22
13-59
993-6
3-55
779
991*4
4-88
10-68
989-2
6-29
13*74
993-5
3-61
7-92
991-3
4-94
10-81
989-1
6-35
13-87
993-4
3-67
8-05
991*2
5-01
10*96
989-0
6*42
14-02
QQQ "Q
3.7*3
8.1 Q
QQ-l .1
c A7
U'OQ
yyo o
993-2
/ o
3-78
J.O
8-29
. L 1
991*0
5-13
v/y
11-22
988-9
6-49
14*17
QQO ,-|
3 '84
O 4O
988*8
6'55
14*30
993-0
Orr
3-90
8-55
990-9
5*20
11-38
988-7
6-62
14-45
QQO'8
5*26
11*51
988*6
6*69
14*60
992-9
3-96
8-68
y yu o
990-7
5*32
11-64
988-5
6*75
14*73
The specific gravity of the spirit having been found to be 991-5,
this by the table is equal to 10*55 per cent, of proof spirit, 1 or
4'82 per cent, of absolute alcohol by weight.
5. Acidity. The acidity of beer is chiefly due to organic acids
and acid phosphates.
It was formerly believed that the acidity of beer was due to
acetic acid, and Graham, Hoffmann, and Redwood based their
experiments on this assumption. It is now known, however, that
newly brewed beer contains scarcely any acetic acid, although the
acidity in original gravity determinations is still expressed in
terms of percentage acetic acid. The percentage of acidity in a
beer has a direct bearing upon the determination of the original
gravity, since if acid exists it must have been formed at the
1 Proof spirit has the specific gravity 9198, and contains 49*24 percent, by
weight and 57 "06 per cent, by volume of alcohol.
METHODS OF ANALYSIS
251
expense of the alcohol or sugar, which will therefore be indicated
too low by the original gravity experiment. Allowance for such
contingency has been made by the investigators mentioned, who
have published the following table, by which any excess of normal
acidity may be calculated back to " spirit indication " and allowed
for.
FOR ASCERTAINING THE VALUE OP THE ACETIC AciU.
Excess
per cent.
Corresponding Degrees of " Spirit Indication."
Acid in
the Beer.
00
01
02
03
04
05
06
07
08
09
o
02
04
06
07
08
09
11
12
13
1
14
15
17
18
19
21
22
23
24
26
2
27
28
29
31
32
33
34
35
37
38
3
39
40
42
43
44
46
47
48
49
51
4
52
53
55
56
57
59
60
61
62
64
5
65
66
67
69
70
71
72
73
75
76
6
77
78
80
81
82
84
85
86
87
89
7
90
91
93
94
93
97
98
99
1-00
1-02
8
1-03
1-04
1-05
1-07
1-08
1-09
1-10
I'll
1-13
1*14
9
1-15
1-16
1-18
1-19
1-21
1-22
1'23
1-25
1-26
1-28
10
1-29
1-31
T33
1-35
1-36
1-37
1-38
1-40
T41
1-42
The normal acidity of beer is assumed to be 0*10 per cent.,
expressed as acetic acid, and any larger amount is allowed for by
the method mentioned.
For example, suppose we find by experiment that the beer
contains an acidity equal to 0'18 per cent., expressed as acetic
acid. The Inland Revenue allow in their calculation O'l per cent.,
therefore there is a remainder to be accounted for of O08 per
cent. By referring to the table we see that 0*08 corresponds to
O'l 2 degree of "spirit indication," and this 0*12, added to our
previous "spirit indication," = 8-6 (8'5 + 0*12), which by table
gives 37*0 as against 36'5 originally found, which raises the
original gravity before mentioned from 1060*5 to 1061.
In order to determine the acidity in beer the process is as
follows :
One hundred c.c. of the beer at 60 F. (15'5 C.) are added to
a porcelain dish and titrated with decinormal alkali, ascertaining
the exact point of neutrality by means of delicate, newly prepared
litmus paper. 1
1 It is preferable to filter the beer before titrating, and so get rid of the free
C0 2 , which would interfere with the litmus blue colour. The test with litmus
should not be carried out in gaslight.
252 THE BREWER'S ANALYST
N
Suppose, for example, we have employed 17*5 c.c. alkali to
effect neutrality; the calculation is then as follows:
N
Each c.c. of - alkali corresponds to '009 gram lactic acid and
'006 gram acetic acid, but, as for original gravity purposes the
acidity is reckoned as acetic acid, so we here express it in that
manner; hence 17'5 x '006 = 0*10 per Cent, acetic acid, which
is normal, so that no correction is necessary for this particular
beer in the original gravity determination. In analytical results,
however, the acidity of a beer is usually expressed in terms of
N
lactic acid, the alkali used being multiplied by '009 ; thus
17-5 x '009 = 0*157 per cent, lactic acid.
Whichever way the acidity may be expressed, we have little
or no knowledge as to the character of the acid-reacting
substances present. It is not unusual, however, to express the
acidity in terms of volatile and non- volatile acids. Thus the
acidity of 100 c.c. of the spirit at the time of taking the original
gravity is determined and expressed as volatile or acetic acid, a
similar proportion of the residue being tested and expressed as
non-volatile or lactic acid.
6. Specific Rotatory Power. Filter a sample of the beer
so as to rid it of carbonic acid gas, fill a 1 decimetre tube with
the beer at 68 F. (20 C.), and polarise in the ordinary way.
Should the beer be too dark in colour, as it usually is with mild
ales and always so with stout and porter, it becomes necessary to
decolorise it, and this is best performed, according to Heron, 1 as
follows :
Take 100 grams of dry bleaching powder, treat in a mortar
with about 200 c.c. distilled water until the whole is of a con-
sistency of cream, and then filter. Now take a 100 c.c. flask,
add to it 10 c.c. of this cream together with 50 c.c. of the beer,
and allow to stand for 5 minutes. Now dilute to mark, mix,
filter, and polarise in a 1 decimetre tube at 68 F. (20 C.). The
reading x 2 gives the opticity of the beer, and this is calculated
to 100 parts of dry solids.
Example. Beading in a 1 decimetre tube = 2'8. 2'8x2 =
5 '6 on beer. The dry solids in the beer were found to equal
6*21 per cent.
1 Jnl. Fed. Inst. Brewing, vol. i., 110.
METHODS OF ANALYSIS 253
7. ColOUP. This is determined by Lovibond's tintometer,
using a 1-inch cell for pale ales and a \ inch cell for dark ales.
The tintorial power is expressed on the number of glass or
glasses required to match the colour of the beer.
With pale ales the degrees (1 in cell) vary from 15 to 25 ;
with mild ales from 25 to 30 ; and with dark beers (J in. cell)
from 35 to 50.
There is usually a loss of about 5 in colour from the turning
out of a copper to the collection of a beer in cask or bottle, so
that a copper wort registering 30 would produce a beer showing
about 25.
With beers in much condition bottled beers particularly it
is advisable to filter before filling the cell, as otherwise the
escaping gas masks the true colour.
8. ProteidS Or Albuminoids. These are determined in
beer in precisely the same manner as with malt wort, using 10
c.c. of the beer and expressing the percentage on the dry solids
(p. 208).
9. Mineral Matter Or Ash. Determined in the same
manner as with malt wort, using 100 c.c. of the beer and
expressing the result in percentage on the dry solids (p. 204).
10. Iron. This is determined from the mineral matter or ash,
as explained under Invert Sugar (p. 260).
11. Salicylic Acid. In order to test whether a beer has
been treated with salicylic acid, about 250 c.c. of the sample
is evaporated to about 50 c.c., then transferred to a small flask,
about 50 c.c. ether added, and the whole thoroughly shaken
for a minute or so. The ether extracts the salicylic acid from
the beer, and upon standing should separate as a clear liquid
on the top of the solution. If it does not do so, a little more
ether should be added, the solution again agitated, and allowed
to stand. The solution is then evaporated over the water
bath (not directly over the steam, and in no case over a
Bunsen or other flame on account of the liability of the ether
to catch fire). The residue is dissolved in a little water and one
or two drops of ferric chloride solution added ; a violet coloration
proves the presence of salicylic acid.
12. MaltO-dextrins, etc. In order to ascertain the condition
in which maltose and dextrin exist in a beer, and the proportion
and type of the malto-dextrins which are present, Morris x some
years ago drew up a satisfactory and complete method of analysis
by which the low-type malto-dextrins are calculated from the
1 Jnl. Fed. Inst. Brewing, vol. i., p. 125.
254 THE BREWER'S ANALYST
cupric reducing power and the optical activity before and after
fermentation, the higher-type malto-dextrins and the stable
dextrin being determined in a similar way as in malt wort (p. 221),
the necessary corrections due to other bodies being made as
described. Fermentation of the wort in the presence of cold-
water malt extract removes the whole of the malto-dextrins and
the stable dextrin, so that the cupric reducing power and optical
activity of the residue after such fermentation is due to bodies
other than maltose, dextrin, and malto-dextrins. The determina-
tions and an example of the analysis are as follows :
The original gravity is determined in the usual way, and the
fermented matter calculated from the degrees of gravity lost
corresponding to the "spirit indication."
The original reducing power of the beer is determined on from
3 c.c. to 10 c.c. of the beer, depending on the strength and age ;
200 c.c. are then evaporated to about one-half to' expel the
alcohol, and the residue is made up to the original volume ; it is
then treated in the following manner :
(a) Degradation with Cold-water Malt Extract. Fifty c.c. are
placed in 100 c.c. flask and 2*5 c.c. of cold-water malt extract
are added; the mixture is then digested at 130 F. (55 C.) for
1 hour.
At the end of this time the liquid is boiled, cooled, and made
up to 100 c.c. at 60 F. (15-5 C.). After filtering, the reducing
power (in 5 or 10 c.c.) and the opticity are determined in the
usual way. Fifty c.c. of the malt extract are digested side by side
with the above, then boiled, cooled, and made up to 100 c.c.
The reducing power (in 3 c.c.) and the opticity are then deter-
mined, and the result applied as a correction to the numbers
obtained in (a).
(b) Fermentation. In order to determine the low-type malto-
dextrins remaining unfermented, a second 50 c.c. of the residue
are set to ferment with about 0-25 gram of pressed yeast at about
75 F. (20 C.). When the fermentation is at an end, which it
will be in from 48 to 72 hours, the liquid is cooled, a little
alumina cream added, and the whole made up to 100 c.c. After
filtration the reducing power is determined in the usual manner,
in 5 or 10 c.c. of the filtrate.
(c) Fermentation in the Presence of Cold-water Malt Extract. It
is necessary to correct the numbers in (a) and (b) for the unfer-
mentable and reducing substances present in the beer. In order
to do this, 50 c.c. of the residue are fermented as in (b), but with
the addition of 2 '5 c.c. of cold-water malt extract. When the
METHODS OF ANALYSIS 255
fermentation is complete, the liquid is treated in all respects as in
the last determination, and the reducing power and opticity are
determined in the bright solution, 10 c.c being taken for the
former. But the malt extract itself contains, as we shall subse-
quently see, these reducing and fermentable substances. It is
therefore necessary, in order to arrive at an absolutely correct
result, to ferment 50 c.c. of the extract side by side with the
above ; and after fermentation is at an end, make up to 100 c.c.
and determine the reducing power and opticity of the residue.
The method of calculation is briefly as follows : The low-type
malto-dextrins are obtained by deducting the copper oxide after
fermentation from the original reducing power, and calculating
the difference into maltose. The combined maltose is obtained
by deducting the reducing power, after fermentation with cold-
water malt extract, from that after fermentation above. The
combined dextrin is calculated from the increase in reducing
power after degradation with malt extract. The free dextrin is
found from the opticity after degradation, less that due to the
total maltose and the unfermentable residue. And the unfer-
men table residue is obtained from the reducing power after
fermentation with cold-water malt extract, the proper corrections
for the malt extract itself being applied where necessary.
The following example of the numbers obtained with a pale ale
illustrates the method :
Original gravity, 1062 '08 ; degrees of gravity lost, 42*64.
Original reducing power, 2 -578 grams CuO per 100 c.c.
(a) After degradation, 100 c.c. reduced 3-758 grams CuO, and
the reading in a 100 mm. tube was 19*8 divisions; 5 c.c. of the
malt extract gave 0*4830 gram CuO, and a reading in a 100 mm.
tube of 8*0 divisions.
(b) After fermentation, 100 c.c. reduced 1'990 gram CuO.
(c) After fermentation in presence of malt extract, 100 c.c.
reduced 1*096 gram CuO, and the reading in a 100 mm. tube was
1'8 divisions; the fermented malt extract gave a reduction of
0*0786 gram CuO per 5 c.c., and a reading of 0*8 division in a
100 mm. tube.
When the foregoing determinations are corrected as described
above, we get :
1. Original reduction . . 2 '5 78 grams CuO per 100 c.c.
2. Reduction after degradation 3*275
3. fermentation 1*990
256 THE BREWER'S ANALYST
4. Reduction after fermentation
with addition of malt extract 1-017 grams CuO per 100 c.c.
5. Opticity after degradation . 194 divisions in 100 mm. tube.
6. fermentation
with addition of malt extract 1'84 ,, ,,
The reduction due to the unfermented, low-type malto-dextrins
is then determined by deducting 3 from 1
2-578 -1-990 = 0-588 gram CuO;
that due to the " amyloin-maltose " by subtracting 4 from 3
1-990- 1-017 = 0-973 gram CuO;
that due to the maltose formed by degradation from the "amyloin-
dextrin " by taking 1 from 2
3-275 - 2-578 = 0'697 gram CuO ;
and the unfermentable, non-degradable residue is represented by 4.
The free dextrin is obtained from 5 after deducting 6 plus the
opticity due to the total maltose present after degradation (found
by subtracting 4 from 2).
Calculating the foregoing quantities of CuO into maltose by the
usual factor, we get
0-438 gram unfermented, low-type malto-dextrins calculated as
maltose,
0*724 combined maltose,
0*517 dextrin calculated as maltose ;
and multiplying by 0*95 to correct for the difference in molecular
weight, we get
0-491 gram combined dextrin,
0'756 unfermentable reducing residue, calculated as mal-
tose;
and using the usual factors, we get
1-955 gram free dextrin.
These results are expressed as grams per 100 c.c. of beer;
they are now calculated as percentages on the original wort
solids, obtained from the original gravity, in this case 16,083
grams.
METHODS OF ANALYSIS 25?
The results then are :
Fermented matter . . . . 68 '7 per cent.
Low-type malto-dextrins (calculated as
maltose) . ." . 2 '72
Combined maltose .... 4*51 ,,
dextrin . . . 3 -05
Free dextrin 12-16 ,,
Unfermentable reducing residue (calcu-
lated as maltose) .... 4'76
13. Brilliancy. All beers should be perfectly brilliant and
free from suspended bodies.
When a beer is not bright, some of the causes can be ascer-
tained by the following methods :
(1) Filter the beer through an ordinary filter paper. If the
beer filters bright, the trouble is due either to the presence of
A Normal yeast, or
B Wild yeasts.
If the beer does not filter bright, proceed with test 2.
(2) Pour upon a plate a little of the beer, add a drop or two of
iodine solution. If the beer gives a blue reaction, it is due to the
presence of starch (C). If the beer does not give a starch reaction,
proceed with test 3.
(3) Warm a sample of the beer in a test-tube or beaker. If it
becomes brilliant, the trouble is due to the presence of glutinous
matter or hop resin. To find which of these one has to deal with,
proceed with test 4. If the beer remains cloudy, then proceed with
test 5.
(4) Pour a little of the beer into a test-tube or beaker, and add
a little ether. If the beer remains cloudy, the trouble is due to
the presence of glutinous matter (E). If the beer becomes clear,
the trouble arises from the presence of hop resin (F).
(5) Obtain a deposit from the beer by means of the centrifuge
(fig. 37 or 38, p. 34 or 35), and examine the deposit under the
microscope.
The trouble may thus be traced to the presence of Saccharo-
bacillus Pastorianus, Sarcina, or other bacterial organisms ; or to
the presence of wild yeasts or an excess of normal yeast.
It often happens that the cause of the cloudiness in beer is due
to a combination of simple causes, thus wild yeasts combined
with bacteria; starch combined with bacteria. In the cases of
wild yeasts combined with bacteria, beer does not take finings, or
17
258 THE BREWER'S ANALYST
takes them very badly. In cases where starch exists the fer-
mentation is very sluggish.
SUGAR ANALYSIS.
Invert -sugar Raw sugars Glucose Priming syrups Caramels.
INVERT-SUGAR.
The following are the determinations to be made :
1. Specific gravity of 10 per cent, solution.
2. Extract per cwt.
3. Mineral matter or ash.
4. Dry extract.
5. Moisture.
6. Proteids or albuminoids.
7. Colour.
8. Iron.
9. Acidity.
10. Invert-sugar.
11. Cane-sugar.
12. Specific rotatory power.
13. Unfermentable bodies.
14. Percentage composition of dry extract.
l. Specific Gravity of 10 per cent. Solution; and 2.
Extract per CWt. Carefully weigh 20 grams of the sugar in a
small tared beaker or porcelain dish, add a little distilled water,
and place on the water bath so as to thoroughly dissolve the sugar.
Transfer the solution to a 200 c.c. flask, cool, make to mark at
60 F. (15*5 C.) with distilled water, arid take the specific gravity
by means of the specific-gravity bottle.
Example :
Specific gravity = 1032-10 - 1000 =
119
32-10 x ^ = 35-95 Ibs. per cwt.
3. Mineral Matter or Ash. Weigh 5 grams of the sugar
in a tared platinum dish, add 1 or 2 c.c. of sulphuric acid, and
ignite to ash as described under Malt Analysis (p. 204).
Example. Five grams of sugar taken.
Weight of platinum dish + ash . . . 60708
Weight of platinum dish . . . . 60 -631
077
0-77 x 20= 1-54 per cent.
METHODS OF ANALYSIS 259
The ash may be used for the estimation of iron.
4. Dry Extract; and 5. Moisture. Under the heading
Solution Weight and Solution Factors (p. 57), it has been
explained that the metho(J of ascertaining the amount of solid
carbohydrate matter present in a solution, by evaporating a
known bulk to drynessand weighing the residue, is unsatisfactory ;
since it becomes necessary, in order to remove the last traces of
moisture, to continue heating for a considerable time, and by thus
heating, the organic substance is partially decomposed.
It has therefore been found preferable to ascertain the amount
of matter in solution by taking the specific gravity and dividing
the excess weight over water by a factor, the most generally
adopted one being 3'86. Thus the specific gravity of our 10 per
cent, solution was found to be 1032'10, so that 1032'10- 1000 =
32-10, which divided by the factor 3-86 = 8'316, and this x 10 on
account of it being a 10 per cent, solution = 83 '16 per cent, of
solids.
These solids, however, are only apparent since some of them are
due to the saline bodies contained in the sample. Heron has
shown that the ash of sugars has a density approximately twice
that of the carbohydrates (3 '8 6), that is to say, the divisor is
about 8. In other words, where 1 gram of sugar when dissolved
in 100 c.c. of water gives approximately a specific gravity of
1003*86, 1 gram of the ash of the sugar, added to water and made
up to 100 c.c., gives a specific gravity of 1008.
To be accurate, we should therefore make a correction for the
saline bodies by dividing that portion of the specific gravity due
to sugar by 3'86, and that due to mineral matter by 8'0. Having
ascertained the amount of mineral matter present in the sugar, we
may therefore either deduct the gravity due to this, or, what
amounts to the same thing, after calculating the apparent solids by
the use of the factor 3*86, we may make the correction as follows :
The mineral matter is expressed too high as dry solids in the
ratio of 8 to 3*86, we therefore multiply the ash by 8 and divide
/ Q V
by 3-86, or we use the factor 2'07(- - = 2'07 ) ; then, deducting
\o"S6 /
the result from the apparent solids, we obtain the solids due to
the actual carbohydrate matter thus
Ash = 1-22 per cent, x 2 '07 = 2 '52.
Apparent solids = 83-16 - 2-52 = 80'64 ;
and 80-64 + 1-22 = 81 -86 per cent, dry extract, and
100-00- 81-86 = 18-14 per cent, moisture.
260 THE BREWER'S ANALYST
6. ProteidS OF Albuminoids. These are estimated by
means of Kjeldahl's method, particulars of which are given under
Malt Analysis, p. 207.
N
Example. In titrating the distillate with ammonia, suppose
20
N
the quantity required to neutralise the 75 c.c. of acid equalled
71-9 c.c. Then 75'0 - 71'9 = 3'1 c.c. ^ acid neutralised by the
ammonia derived from the albuminoids originally in 5 grams of
sugar, and 3-1 x '0007 = '00217 x 20 = '04340 x 6'33 = 0'27 per
cent, albuminoids.
7. Colour. The colour of the 10 per cent, solution is taken
by Lovibond's tintometer, using a 1 inch cell and expressing the
result in percentage, i.e. multiplying the number of the glass
or glasses used by 10, thus :
10 per cent, solution required glass No. 3.
3 x 10 = 30 degrees per cent.
The brilliancy of the solution should be noted.
8. Iron. This may be detected and estimated where necessary
from the 10 per cent, solution.
One hundred c.c. of the 10 per cent, solution are* taken in
a Nessler tube, a few drops of acetic acid added, and one or
two drops of potassic permanganate. The presence of iron is
indicated by the blue or greenish-blue coloration produced, and
according to the intensity of the colour so is the quantity of
iron present.
It is very unusual to find sugars containing more than a
mere trace of iron, but should there be any excessive colora-
tion, it is advisable to quantitatively estimate the amount
thus :
One hundred c.c. of 10 per cent, sugar solution taken in a Nessler
tube, two drops of potassic ferrocyanide added.
One hundred c.c. of water taken in a Nessler tube, two drops of
potassic ferrocyanide added, and a standard solution of iron (p. 137)
run in from a burette until the colour of the tube containing the
sugar solution is imitated.
Each 1 c.c. of the iron solution = 0*1 milligram of iron.
The amount of iron solution required = 0'2 milligram, i.e.
0'2 mgm. per 10 grams of sugar, or x 1.0 = 2*0 mgms. per
100 grams of sugar, or 0*002 per cent. It is usual to express
the amount of iron as ferric oxide Fe 2 8 ; 112 parts of
METHODS OF ANALYSIS 261
1 Rf\
Fe=160 parts of Fe 2 3 , so -002 x j-= 0*28 gram Fe 2 O 3
1 1 ^j
per cent.
Instead of employing the sugar solution for the determination
of iron, the ash previously determined may be used for
the purpose, thus :
The ash is dissolved by the addition of a little hydrochloric
acid, the solution then evaporated to dryness to separate the
silica, then again dissolved in hydrochloric acid and the iron
precipitated by the addition of a little ammonia. The solution is
now filtered, the precipitate containing the iron redissolved with
hydrochloric acid, and the solution evaporated almost to a drop in
order to get rid of the great excess of hydrochloric acid, which
would interfere with the reaction later on. This small quantity
of solution is then washed into a Nessler tube, made up to 50 c.c.
with distilled water, and a few drops of potassic ferrocyanide
added. A blue coloration takes place, and this coloration is
matched in another Nessler tube by adding 50 c.c. of distilled
water, about 1 drop of hydrochloric acid, and an amount
of potassic ferrocyanide equal to that added to the previous
Nessler tube. The standard solution of iron is then run
in from a burette until the colour matches, and the calculation
performed as described.
9. Acidity. Occasionally some invert-sugars are purposely
left faintly acid, as they are then of a paler colour. To determine
the acidity, take 100 c.c. of the 10 per cent, solution in a
porcelain dish and titrate with alkali, using litmus paper as
indicator.
Example. One hundred c.c. 10 per cent, solution required
N N
7'5 c.c. alkali. Each c.c. of alkali = '009 gram of lactic
acid: 7 '5 x '009 = '0675 acid in 10 per cent, solution, or 0'67
per cent.
10. Invert SUgar. Ten c.c. of the 10 per cent, solution
are run into 100 c.c. flask and made to mark with distilled
water = 1 per cent, solution.
A burette is filled with this 1 per cent, solution and Fehling's
solution then prepared as follows :
Twenty-five c.c. of copper sulphate solution and 25 c.c. alkaline
tartrate are added to a beaker together with 30 c.c. of distilled
water. The beaker is then placed in a boiling water bath, and
when the contents have reached the boiling point, 20 c.c. of the
262 THE BREWER'S ANALYST
1 per cent, sugar solution are added and the whole boiled for
exactly 12 minutes. The beaker is then removed and the
contents filtered. A good filter paper must be used, or other-
wise some of the CuO is liable to pass through. If such were
the case it would, after standing, be found at the bottom of
the beaker, in which case it becomes imperative to refilter.
Wash the precipitate several times, using about 200 c.c. hot
distilled water for the purpose, and finally wash with about 10
c.c. of strong alcohol ; then dry the paper in the water oven,
transfer to a tared crucible, and burn off; ignite to redness
for 15 minutes, cool under desiccator, and when cold weigh, re-
peating the heating, cooling, and weighing until the weight is
constant,
Example :
Weight of crucible + CuO . . . 6'654> grams.
Weight of crucible .... 6'340
0-314
20 c.c. of 1 per cent, solution gave '314 gram CuO. -314 x Fehling's
factor -4715 = '1480 invert-sugar in 20 c.c., and -1480x~ =
200
7400 invert in 100 c.c. of 1 per cent, solution or 1 gram of sugar.
The sugar therefore contains 74'0 per cent, invert.
1 1 . Caiie-SUgar. Cane-sugar does not reduce Fehling's
solution, we have therefore to invert it as follows :
Ten c.c. of the 10 per cent, sugar solution are added to a
100 c.c. flask, 50 c.c. of distilled water added, together with 5 c.c.
4
hydrochloric acid. The flask is then placed on the water
bath and the contents maintained at a temperature of 150 F.
(65'5 C.) for 20 minutes. The flask is then removed, the
contents cooled to 60 F. (15'5 C.), neutralised by the addition
of 5 c.c. alkali, made up to mark with distilled water, and
thoroughly agitated.
We now have a 1 per cent, solution containing the original
invert-sugar plus that produced by the inversion of any cane-
sugar originally present. The increased proportion of invert-
sugar now found in this solution gives us the amount of cane-
sugar. We therefore carry out a Fehling's test with this 1 per
cent, solution, identical with that previously carried out with the
invert-sugar, and from the cupric oxide reducing power calculate
the amount of total invert-sugar in the sample. By then de-
METHODS OF ANALYSIS 263
ducting one from the other and multiplying the increase of invert-
sugar by '95, 1 we arrive at the percentage of cane-sugar originally
present.
Example :
20 c.c. of 1 per cent, solution gave '318 gram CuO.
318 x Fehling's factor '4715 = '150 invert in 20 c.c.
100
150 x = '750 invert in 100 c.c. 1 per cent, solution,
'20
or 1 gram of sugar = 75*0 per cent.
In our former experiment we have invert-sugar = 74'00 per
cent.; so 75*0 - 74'0 = 1*0 per cent, sugar due to cane, which
x -95 = 0*95 per cent, cane-sugar.
Instead of carrying out the inversion of the sugar by the
action of acid, yeast may be employed, thus :
Ten c.c. of the 10 per cent, solution are added to a 100 c.c.
flask, together with 20 c.c. distilled water, and digested with a
small quantity of washed and pressed yeast ('5 to 1 gram) at
125 F. (51-6 0.) for 5 hours. The solution is then heated to
expel alcohol, cooled to 60 F. (15 '5 C.), a little alumina cream
added, made up to 100 c.c. ( = 1 per cent, solution), filtered, and
the cupric oxide reducing power determined as described.
12. Specific Rotatory Power. The optical activity of
invert-sugar is levo-rotatory (-). If dextro-rotatory ( + ) the
sugar either contains much cane-sugar or there is present an
admixture of glucose, and the amount of such should be calcu
lated from the specific rotatory power. Although, however,
invert-sugar theoretically consists of equal parts of dextrose and
levulose, commercial samples always contain an excess of dextrose,
owing to a slight decomposition of the levulose during inversion.
Allowance for this must be made when attempting to estimate
the admixture of glucose.
Ten per cent, solution boiled and cooled to 68 F. (20 C.)
examined by the polarimeter in a 1 decimetre jacketed tube.
Specific rotatory angle = 1-26 x 10 = [a] D - 12*60 on sugar.
13. Unfermentable Bodies. All sugars contain a proportion
of unfermentable matters which have both a cupric reducing
and an optical activity. It is usual to make a correction for
these matters in the case of glucose, but this is hardly necessary
1 The molecular weight of cane-sugar (C 12 H2 2 O n ) = 342 ; that of invert-sugar
(C 12 H 24 12 ) = 360. 360 parts of invert-sugar are produced from 342 parts of
cane-sugar, hence 342 * 100 = '95.
264 THE BREWER'S ANALYST
in the case of invert-sugar. For all purposes of commercial analysis
the usual way is to calculate them by difference as follows :
Total solids ...... 81 '86 per cent.
Less bodies determined
Invert-sugar . . . . 74'00
Cane-sugar . . . .0*95
Albuminoids . . . .'27
Ash ... . 1*54
- 76-76
Unfermentable bodies . 5-10
H. Percentage Composition of Dry Extract. The
determinations are made on a rule-of-three basis as follows :
Dry extract . . 81 '86.
Mineral matter . . 1 ^^I-= 1 '89 percent.
ol'ob
0-27x100 AQ
Albuminoids . . Q ^ 0'33
Invert-sugar . . 1L = W-M
Cane - 8 u g ar. . . -= M5
Unfermentable bodies . 5 ' 10xloo = 6*24
81*86
100-00
The full analysis works out as follows :
INVERT-SUGAR.
1. Specific gravity of 10 per cent.
solution ..... 1032-10
2. Extract per cwt. (112 Ibs.) . . 35-95
3. Mineral matter .... 1'54
4. Dry extract ..... 81-86
5. Moisture ...... 18*14
6. Proteids or albuminoids . . . 0*27
7. Colour ...... 30
8. Iron ...... 0-2
9. Acidity . ; . . . . 0'67
10. Invert-sugar ..... 74'00
11. Cane-sugar ..... 0*95
12. Specific rotatory power . . . 12*60
13. Unfermentable bodies 5*10
METHODS OF ANALYSIS 265
14. Percentage Composition of Dry Extract.
Invert-sugar , . . '-. . . 90 '3 9
Cane-sugar . . . . . 1*15
Unfermentable bodies . . . 6 "24
Proteids or albuminoids . . .. "33
Mineral matter or ash 1'89
100-00
RAW SUGARS.
The determinations to be made with all raw sugars are the
same as with invert-sugar, and are carried out in precisely the
same manner.
GLUCOSE ANALYSIS.
The following are the determinations to be made :
1. Specific gravity of 10 per cent, solution.
2. Extract per cwt.
3. Mineral matter.
4. Dry extract.
5. Moisture.
6. Proteids or albuminoids.
7. Colour.
8. Iron.
9. Acidity.
10. Cupric oxide reducing power.
11. Specific rotatory power.
12. Cupric oxide reducing power and specific rotatory
power after fermentation.
13. Unfermentable bodies.
14. Percentage composition of dry extract.
The whole of these estimations, excepting No. 12, are determined
exactly as with invert-sugar. It will therefore only be necessary to
repeat the cupric oxide reducing power No. 10, and specific rotatory
power No. 11, to make the determination of No. 12 explicit.
10. Cupric Reducing" Power. Seventeen c.c. of the 1 per
cent, solution gave '298 gram CuO, and '298 x Fehlings factor '4535
1 00
= -1351 x~r = *7941 dextrose in 1 gram of sugar. The total
reducing sugars expressed as dextrose therefore = 79 '41 per cent.
11. Specific Rotatory Power. Determined from a 10 per
cent, solution by polarimetric examination at 68 F. (20 C.) in a
1 decimetre tube.
266 THE BREWER'S ANALYST
Example. Specific rotatory angle = + 5'20. 5'20 x 10 = + 52
[a] D on sugar.
12. Cuprie Oxide Reducing" Power and Specific Rota-
tory Power after Fermentation. One 100 c.c. of a 20 per
cent, solution are placed in a 200 c.c. flask and the whole
sterilised by boiling for a few minutes and then cooling to about
75 F. (23-8 C.).
Two to three grams of washed and pressed yeast are now added,
and the mixture set on the forcing tray to ferment.
When the fermentation is complete, no further evolution of C0 2
being observed, the solution is boiled to expel the alcohol, then
cooled and a little alumina cream added, and finally made to mark
(200 c.c.) at 60 F. (15'5 C.) with distilled water and filtered.
The reducing power of this 10 per cent, solution gave '293 gram
CuO x 50 = 14-65 x Fehling's factor '4535 = 6'64 per cent, reducing
power expressed as dextrose.
The specific rotatory power of the fermented sugar solution,
examined in a 2 decimetre tube at 68 F. (20 C.), gave a reading of
1-99 -i- 2 = 9-95 on sugar.
From these figures the maltose and dextrose proportions are
derived, thus :
Total sugars expressed as dextrose . 7 9 '41 per cent.
Unfermented sugar expressed as
dextrose ..... 6 '64
Sugar removed by fermentation 72-77
Total specific rotatory power. . . . 52*00
Specific rotatory power after fermentation . 9-95
Rotatory power removed by fermentation 42'05
The maltose and dextrose having both been removed by fermenta-
tion, the loss in reducing and opticity is due to these substances,
and from their representative figures we calculate the proportion
of each of these bodies originally in the solution, thus :
Maltose has a K 61 * and a specific rotatory power of [a] D 135-9.
Dextrose has a K 100 and [a] D 51*7.
One part of dextrose therefore has an opticity of "517, and
the reducing sugar, which has been calculated as dextrose,
multiplied by this value, gives 72-72 x -517 = 37'59. Now, if
our sugar were pure dextrose, the opticity would be 37*59. The
1 K equals the reducing power of a sugar compared with dextrose, the latter
being taken as 100. Sixty-one parts of maltose precipitate the same amount of
cupric oxide as 100 parts of dextrose, therefore its reducing power is expressed
as K 61.
METHODS OF ANALYSIS 267
sugar, however, has an opticity of 42 '05 or 4*46 above that
required for dextrose, this excess opticity being due to the
presence of a proportion of maltose, which has a higher opticity
than dextrose. Maltose has an opticity of 135 '9, but so far we
have expressed maltose present in terms of dextrose ; we have
therefore to ascertain the opticity which corresponds to maltose
when thus expressed.
It will be seen that our maltose is expressed as dextrose, or
K 100, and not as K 61 ; we have therefore to calculate the angle
to correspond with this K 100, thus :
135-9 x^ = [a] D 222-8.
From this figure we deduct the K 100 = [a] D 51'7, which gives us
[4)171-1.
The rise of opticity in our sample is 4'46, therefore
4 ' 46x I7FI = 2 ' 60 -
Therefore :
Total dextrose 7 2 -7 7
Dextrose due to maltose .... 2*60
Dextrose in sample . . . 70' 17
The amount of maltose which the dextrose represents has now
to be determined, thus
The dextrose with K 100 is calculated to maltose K 61 as
follows :
I r\r\
2-60 x ^ = 4-26 per cent, maltose.
61
We now deduct the albumin and mineral matter from the
residue after fermentation to obtain the dextrin, gallisin, and
other bodies, which are usually grouped together, as their separate
determination is unsatisfactory.
Example :
Dextrose 70'17 per cent.
Maltose 4-26
Albumin ..... '90
Mineral matter .... '86 ,,
Moisture 16-78
Dextrin, gallisin, unfermentable
bodies
268 THE BREWER'S ANALYST
EXPRESSED AS PERCENTAGE COMPOSITION OP DRY EXTRACT.
Dry extract . . . 83'22
70-17 x 100
Dextrose . 83^22 = 84 - 31 per cent.
4-26 x 100
Maltose . . . . 83'2 9 = "
0-90 x 100
Albumin .... 83'2 9 = ^'^
0-86 x 100
Mineral matter . . . Q0 00 = 1 04 ,,
OO'AA
Unfermentable bodies . . Q0 00 = 8 '45
100-00
PRIMING SYRUPS.
These are prepared from either pure cane-sugar, invert-sugar, or
glucose, and the determinations to be made are precisely as for
invert-sugar, or for glucose, should the syrup be manufactured
from the same, a point quickly ascertained by means of a polari-
metric observation.
CARAMEL.
The following are the determinations to be made :
1. Specific gravity of 10 per cent, solution.
2. Extract per cwt.
3. Dry extract per cent.
4. Moisture.
5. Mineral matter or ash.
6. Colouring power.
7. Deportment with beer and proof spirit.
8. Fermentability.
9. Cupric oxide reducing power.
10. Specific rotatory power.
Numbers 1, 2, 3, 4, 5, and 9 are determined as described with
invert-sugar; numbers 6, 7, 8, and 10 being estimated as
follows :
6. Colouring* Power. The colour test, so far as caramels are
concerned, is of exceptional importance, since the value of a
caramel depends upon the tintorial power it is capable of yielding.
Obviously, the greater the colouring capacity of a caramel, the
METHODS OF ANALYSIS 269
greater is its value, provided, of course, other conditions are
normal.
It is best to make a '01 per cent, solution by weighing 1 gram
of the caramel in a small, tared dish or beaker, adding a little
water and raising to the boil so as to dissolve it, and then transfer-
ring the solution to a litre flask, cooling, and making to mark with
water at 60 F. (15'5 C.). The brilliancy or opaqueness of the
solution should be noted, and if cloudy, a little of it should be
filtered through a dry filter paper before testing its colour value.
The colour may then be ascertained by filling a 1 inch cell of
Lovibond's tintometer, and the result expressed in degrees
thus :
Example. -01 per cent, solution required glass No. 20 in
1-inch cell. Colour value = 20 degrees on '01 per cent, solution.
7. Deportment with Beer and Proof Spirit. The
qualitative tests for a good caramel are solubility without cloudi-
ness in proof spirit; or, when added to pale ale in sufficient
quantity to impart the colour of ordinary mild ale, the caramel
should cause no deposit or cloudiness even after long standing.
The latter is a very severe test ; but it is necessary because (a) a
deposit indicates a disturbance of the carbohydrate equilibrium
of the beer, and (/;) when a deposit is found it not only consists
of the caramel colouring matters, but carries down also some of the
original colouring matter of the beer.
8. Fermentability. A solution of the caramel, after boiling
and cooling to 60 F. (15-5 C.), is made up to a specific gravity
of 1050, 200 c.c. measured and added to a boiling flask, a little
pressed yeast added, and the flask, after shaking, placed on the
forcing tray.
When fermentation is complete the flask is removed and the
contents boiled, the alcohol being thereby expelled. The solution
is then cooled, made up to 200 c.c. at 60 F. (15'5 C.) with dis-
tilled water, filtered, and the specific gravity taken. The loss in
specific gravity indicates the degrees of fermentability.
10. Specific Rotatory Power. A solution of the boiled and
cooled caramel, made to 1050 specific gravity, is decolorised as
explained under Wort Analysis (p. 201) and examined by the
polarimeter at 68 F. (20 C.). Good caramels show a low
opticity.
MALT CULMS OR ROOTLETS.
Oil. Determined as per prepared raw grain, p. 226.
Albuminoids. Determined as per malt, p. 207.
PART VII.
ARSENIC.
As is well known, since the deplorable accidental contamination
of beer by arsenical sugar in 1900, and the subsequent discovery
by Thompson and Escourt of traces of arsenic in malt, it is now
absolutely necessary to keep beer free from arsenic, at least to the
extent recommended by the Royal Commission on Arsenic, the
maximum being fixed at one-hundredth part of a grain per pound
of malt or per gallon of beer.
MALT.
In the manufacture of malt, the barley when vegetated is dried
off in the majority of cases by the direct heat evolved from the
burning of oven coke, anthracite co;il, or a mixture of the two,
and these materials contain arsenic to a variable extent.
It is not unusual to detect amounts of arsenic varying from
J^th to 2-J-o^h part of a grain per Ib. of these materials, and the
question arises what quantity of the arsenic found in such
materials is imparted to the malt.
Obviously the first point is the quantity of fuel used in drying
off the malt, and this naturally varies with the system adopted arid
still more with the construction of the kiln. Roughly, however,
it may be taken to vary from ith to Jth of the weight of malt it
has to dry.
Secondly, it must be borne in mind that if sulphur is mixed
with the fuel the so-called fixed arsenic may become volatile ;
this, however, is negligible, because it is rarely that any considerable
amount of sulphur is used intermixed with the fuel, the practice
in burning sulphur, if at all resorted to, being to burn it separately.
Taking it that the fuel contains -f^ih of a grain of arsenic per
Ib., and assuming that the whole quantity is evolved and retained
in the malt, the latter will then show from g^th to ^o^th of a
270
ARSENIC 271
grain per Ib. Experience shows, however, that only about half
the quantity of arsenic in the fuel finds its way into the malt,
partly because a considerable fraction of it settles out on the walls,
arches, and baffle-plates before it reaches the grain, and partly
because some of it remains behind in the ash.
Under these circumstances, a malt dried over fuel containing so
high an arsenic content as ^th of a grain per Ib. would be likely
to show from T ^th to T J^th of a grain of arsenic per Ib.,
according to the amount of fuel used per quarter of malt. It
therefore appears that the question of malt contamination by
arsenic is a very much overrated one, and that it is indeed seldom,
and in fact only in very rare instances, that a malt is found to
contain more than ^J^-th part of a grain per Ib. Nevertheless, in
view of the lesson taught in 1900, brewers and maltsters cannot be
too careful, and all fuel used for drying malt should at any rate
certainly not contain more than the -^th of a grain per Ib., and all
malt produced or purchased should not contain more than the
part of a grain of arsenic per pound.
HOPS.
In the drying of hops the quantity of fuel used is different to
that in drying malt. It may be taken as a fact that for every unit
weight of hops an equal weight of fuel must be used in drying
them, and assuming that all the arsenic in fuel (reckoning the
fuel to contain so high a rate as in the former case, viz., ^th grain
per Ib.) got into the hops, the hops will show -yg-th of a grain of
arsenic per Ib. as against ^i^th to ^tr^th in malt. One has there-
fore to be very careful with regard to the arsenic content of hops,
since the construction of the oast-house kiln and the conditions of
drying, as well as the large amount of fuel used, all tend to allow
more of the arsenic content of the fuel to pass into and be retained
by the hops, it being in fact roughly estimated that at least |rds
of the arsenic content of the fuel are retained by the hops. Even
so, however, the amount of hops used in both copper and cask in
the manufacture of beer is small compared with that of malt, so
that any hops showing even so high a quantity of arsenic as the
J^th of a grain per Ib. are sufficiently free from arsenic for all
purposes, and in comparison with malt showing such amounts as
previously mentioned, would not even then bring the beer within
the Royal Commission's limit of y^yth part of a grain per gallon.
It is safest, however, when purchasing hops, to either obtain a
guarantee that the hops do not contain more than the
272 THE BREWER'S ANALYST
part of a grain per lb., or to test the same, rejecting those that
contain more.
SUGARS.
The amount of arsenic commonly occurring in sugars varies
from yjy^th to ^J^-th part of a grain per lb., and the majority are
now almost free. At any rate, provided they do not contain more
than T J-^th part of a grain per lb., they are sufficiently pure in
this respect for all purposes.
It should be remembered, if using sulphuric acid as a convert-
ing agent in cases where cane-sugar is inverted by acid on the
brewery premises, that the sulphuric acid employed is of the
purest character and almost free from arsenic. As a rule the
acid will be found to contain quantities of from 0*2 to 0*4 per
cent., and such quantities may be ignored ; but anything beyond
0'4 per cent, should result in the rejection of the acid for a purer
supply.
BEER.
The surest test of all is that of the beer, and it is now the
usual practice in numerous breweries for the analyst to test, for
arsenic, every beer as racked, the detection of anything approach-
ing the T ^th part of a grain of arsenic per gallon being sufficient
to arouse suspicion and result in a complete analytical survey, in
this direction, of all materials, such as water, hardening ingredients,
malt, hops, sugars, antiseptics, yeast foods, and finings. By these
means an excessive quantity of arsenic in any of these materials is
quickly located, and means immediately taken to reduce the evil
and once more come back to safe limits.
ARSENIC TESTS.
ReinSCh Test. Of all tests this is the most simple, but is
absolutely useless for very minute quantities. It is performed
as follows :
About 200 c.c. of the beer, wort, or other solution, or about
2 grams of a solid substance ground to powder and mixed with
about 200 c.c. of distilled water, are placed in a porcelain dish
together with about 20 c.c. of pure hydrochloric acid. A small
strip of polished copper foil is then added and the mixture boiled
for a short time. If arsenic is present, the surface of the copper
foil will become coated with a dark-grey film of As 2 Cu 5 .
The strip of copper is now removed from the dish, carefully
ARSENIC
273
dried, and then folded and placed in a warmed, drawn-out glass
tube. 1 The tube is then heated very slowly over a small Bunsen
flame, when a white crystalline sublimate of As 2 3 will form on
the drawn-out portion of^the tube. This white sublimate is
known as the "mirror."
By making a standard solution of arsenious oxide and adding
a definite quantity to a given bulk of acid solution, and boiling
the same with a strip of copper, the arsenic in the solution will
be deposited on the copper ; and upon drying the copper and
subliming it in a drawn-out glass tube as previously stated, a
standard mirror is obtained.
By increasing or decreasing the strength of the arsenical solu-
tion, and repeating the experiment, a further standard mirror is
obtained, and so on, so that
numerous standard mirrors
may be prepared. After sub-
limation the drawn-out portion
of each glass tube is broken
off and both ends sealed by
the blow-pipe. The tubes are
then attached to strips of
cardboard, and the quantity
of arsenic which each mirror
, . . , ,
represents is written thereon.
If we take one of these tubes and examine it under the micro-
scope, employing for preference a yVinch objective, transparent,
colourless, regular octahedra and tetrahedra crystals, will be seen.
The mirror obtained from the sublimation of the copper
employed for testing our beer, wort, or other substance is now
compared with the standard mirrors, and the amount of arsenic
calculated to percentage from the original quantity of substance
or solution employed.
Marsh Test. This is a far more reliable test than the Reinsch,
and is performed as follows :
Fit a 4-ounce flask with a thistle funnel and bent delivery
tube as shown (fig. 77). Attach to the latter, by means of a
rubber joint, a tube of hard glass about 4 inches in length and
drawn out at the end to small bore, and support this on a ring
of a retort-stand. Cover the bottom of the flask with granulated
zinc, free from arsenic, add a little water, and then pour in
through the funnel tube a little strong hydrochloric acid.
After hydrogen has been evolved and expelled all the air from
1 Tubes of even bore and ready drawn may now be purchased.
18
FIG. it.
274
THE BREWER'S ANALYST
the flask, there will be no risk of an explosion occurring when the
gas is lighted ; but it is well to cover the flask with a cloth before
kindling the hydrogen. Now kindle the hydrogen and pour the
solution to be tested into the flask through the thistle funnel.
Press down upon the flame the inside of a clean dry porcelain
dish, when a dusky black film of As may be deposited upon the
cool surface.
Instead of employing a porcelain dish, the drawn-out tube may
be heated by the tip of a small Bunsen flame as shown in fig.
79, when the arsenious oxide evolved will be sublimed, forming
a mirror, as in our previous experiment.
FIG. 78.
The tube is then broken off, both ends sealed with the blow-
pipe, and the mirror compared with the previously prepared
standard mirrors, the amount of arsenic in the quantity of
substance dealt with being thus estimated.
It is as well to mention that in both the experiments the dark-
grey colours produced on the copper in the Reinsch test, and the
black deposit produced on the porcelain dish in the Marsh test,
may be due to antimony. and not arsenic. To test whether this
is so or not, a little freshly prepared solution of bleaching powder,
containing calcium hypochlorate (CaCl 2 2 ), poured upon the copper
or black film on the dish, will rapidly dissolve and remove arsenic,
whilst it has no action on antimony. The mirror produced in
both cases may be recognised by its solubility in CaCl 2 2 , and by
the crystals seen on microscopical examination.
Instead of employing an ordinary boiling flask as shown in fig.
77, it is now more usual, and certainly safer, to employ a Tyrer
Marsh flask, different forms of which are shown (figs. 78 and 79).
ARSENIC 275
These flasks consist of three separate pieces : the flask which holds
the substance or solution being experimented with, the stopper with
bulb .connection, and the thistle funnel or stop-cock graduated
tube. A few pieces of granulated zinc are added to the flask
together with a little distilled water, the bulb stopper is then
inserted, and then the thistle funnel or graduated tube. Acid is
now added through the funnel or from the graduated tube, and
upon coining in contact with the zinc hydrogen is set free. The
gas passes up through the side tube in the stopper, circulates
through the inner loop into the bulb, and from there makes its
escape. Upon lighting the hydrogen, after all the air is expelled,
and proving that the zinc and acid are free from arsenic, the light
FIG. 79.
is put out and the stopper removed ; after which the substance
to be tested is added and the experiment continued, the mirror
produced, if arsenic is present in the substance, being obtained
and compared with standard mirrors in the manner already
described.
Marsh-Berzelius Test. This is carried out precisely as
described with the Marsh test, excepting that a slight modification
is introduced with regard to the apparatus. The modification
consists in employing a drying tube, that is to say, a tube con-
taining calcic chloride (so that the hydrogen evolved is free from
moisture) ; and a roll of filter paper (previously soaked in a strong
solution of lead acetate and then dried), so that any sulphuretted
hydrogen evolved may be absorbed.
The following method of estimating arsenic, and in which the
Marsh-Berzelius apparatus is employed, is the most reliable and
accurate for the purposes of the brewer's analyst.
276 THE BREWER'S ANALYST
Apparatus. The apparatus required for the test consists as
shown (fig. 78 or 79) in a flask of about 50 c.c. capacity fitted
with either a graduated tube, thistle funnel, or funnel and stop-
pipe, the tube of which passes through the bulb stopper of the
flask.
From the tube leading from the bulb stopper of the flask a
drying tube is fitted by means of a piece of rubber tube. This
tube is loosely plugged at both ends with cotton wool, and the
centre portion filled with calcic chloride ; a roll of filter paper
(previously soaked in lead acetate and then dried) is also placed
at one end of the tube. The object of the chloride of calcium is,
as previously described, to dry the gas, that of the roll of filter
paper to absorb any traces of sulphuretted hydrogen which may
be evolved.
A piece of glass tube 200 mm. long, 4J mm. in internal, and
6J mm. external, diameter, is softened in the blowpipe- flame and
drawn out from the middle for about 30 mm. and again drawn
out at one end to about 70 mm. ; the diameter at the beginning of
the drawn-out portion in the middle of the tube (for receiving the
mirror) being about 2 mm. in internal diameter.
This tube is now attached to the end of the drying tube con-
nected with the flask, and is supported in position by resting on
a ring of a retort-stand.
A piece of fine iron gauze 20 mm. wide is wrapped round the
tube at the point shown in fig. 79, and heated by a Bunsen flame.
This is more satisfactory than applying the flame directly to the
tube, and conduces to the formation of more uniform mirrors.
The Bunsen flame should be about 4 inches long, and protected
till near the point by a conical chimney. The tube should be
heated about half an inch from the shoulder at the point shown.
Beer. Take 50 c.c. of the sample in a 200 c.c. Jena glass flask
and evaporate to a syrup on a sand bath. Add 25 c.c. strong
nitric acid and 5 c.c. strong sulphuric acid; place on the sand
bath, having taken away the flame ; allow the first violent action
to subside, the acid fumes from which may be drawn away through
a glass tube in the mouth of the flask by a water Sprengel pump
through a solution of caustic soda in a Wolffs bottle. Then
apply a Bunsen flame to the sand bath, and evaporate till the
liquid begins to darken. When this occurs, add strong nitric
acid in quantities of 3 c.c. at a time (the total quantity of nitric
acid required varies from 30 to 50 c.c., depending on the
quantities of organic matter present), until on further heating it
continues colourless, and fumes strongly of sulphuric acid ; cool,
ARSENIC 277
dilute with 10 c.c. of water, and boil down to break up the nitro-
sulphuric acid formed. When cold, dilute with 10 c.c. of water
and deliver into the apparatus.
Testing 1 Reagents. A- blank on the reagents and apparatus
used should be made by boiling down 100 c.c. HN0 3 and 5 c.c.
H 2 S0 4 till all nitric is expelled, diluting and boiling down (this
procedure removes every trace of nitric or nitrous acid), again
diluting, and testing in the apparatus as above described.
Malt Sugar, Caramel, Hops, Yeast, etc. Take 5 grams
of malt or other solid organic substance, add 25 c.c. HN0 3 , and
heat gently till the first violent action is over; then add 5 c.c.
sulphuric acid and proceed as for beer (a total of from 50 to 75
c.c. of nitric acid will be required).
The Marsh-Berzelius apparatus (50 c.c. flask) should
contain about 20-25 grams zinc. The CaCl 2 in the drying tube
should be renewed as soon as the first few pieces become wet.
Action is started by adding 5 c.c. of dilute sulphuric acid (10
parts concentrated sulphuric, 20 of water, and 1 part of a 10 per
cent, solution of pure crystallised copper sulphate). Allow the
evolution of gas to go on (the exit tube for the hydrogen being
heated in the usual manner by means of a small Bunsen flame)
until the hydrogen nearly ceases to be evolved ; then fill up the
tube and funnel of the Marsh-Berzelius apparatus with the
solution previously treated as above, and allow the whole to run
in, if only a very minute quantity of arsenic is supposed to be
present ; or run in an aliquot part if a larger quantity is supposed
to exist. In about 15 minutes the flask is washed with 5 c.c.
more of the above acid, which is added to the hydrogen flask in
small quantities at a time to keep up the evolution of gas for a
total of from 30 to 35 minutes after the first introduction of
the previously treated beer, by which time, with this sized
apparatus, all the arsenic will have passed off.
The hydrogen flame at the end of the drawn-out portion should
be about 2 mm. long, and maintained as constant as possible:
too slow a flow almost invariably gives double mirrors ; too fast a
flow gives irregular ones, difficult to compare with the standards.
Zinc. Twenty grams of zinc should be tested by the action of
30 c.c. of dilute H 2 S0 4 one of acid to two of water containing
a little copper sulphate to start the reaction ; there should be
absolutely no trace of arsenic mirror on the drawn-out portion of
the glass tube.
Another experiment should then be made, adding a minute
quantity of arsenic, say, equal to yj^th of a grain per gallon (when
278 THE BREWER'S ANALYST
working on 50 c.c.), equal to 0'029 part per 1,000,000, or an
actual weight of 0*00143 mgrm., and compared with a standard
tube to make sure that the zinc contains nothing which will hold
back minute quantities of arsenic.
Standard mirrors for comparison are made by introducing
into the apparatus known quantities of arsenic, say, commencing
with J^th of a grain per gallon when working on 50 c.c. A
convenient method of preparing the standard mirrors is to employ
a solution of arsenious acid containing 0*007145 of a mgrm. of
As 2 3 per 1 c.c. One c.c. of this solution is equal to T J^th of a
grain of As 2 3 per gallon when using 50 c.c., or T J^th of a grain
per Ib. when using 5 grams of material. This solution is suitable
for standards between -Jg-th and T J^th of a grain per gallon, and a
solution of T Vth this strength may be employed for the standard
mirrors between y^th and y^^th of a grain per gallon.
The mirrors which will be found most useful are ^V^ n - eV^h)
^gth, and T ^o tn ^ a g ra i n P er gallon, corresponding to 2'0, l - 5
1-25, and 1-0 c.c. of the stronger solution ; and Yryth, T yth, T j^rd,
T^ th awth, Tri<yth, 3 J TJ -rd, T ^th, ^th, and TTr V(7 th of a grain
per gallon, corresponding to 9'0, 8-0, 7'0, 6'0, 5-0, 4'0, 3'0, 2'0,
1*5, and I'O c.c. respectively of the weaker solution.
Preservation of the Mirrors. When the test has been
completed, the point of the drawn-out portion of the glass tube is
sealed by the blowpipe flame and also the other end of the tube.
Without sealing, the tubes will keep for many months ; but as it
is possible that the mirrors may fade by exposure to light and air,
they are, under the circumstances, best sealed and preserved in an
atmosphere of hydrogen. Lastly, the importance of all reagents
being absolutely free from arsenic cannot be overrated. Nitric
acid can easily be obtained absolutely free from arsenic, and so
also can zinc, as it is now manufactured electrolytically and freed
from iron by treatment with acid for the purpose. It is advisable,
however, with both hydrochloric and sulphuric acids, to dilute them
with about Jrd water, to add about 1 gram per litre of chromic
acid, and distil. With sulphuric acid this operation suffices to
free it from any trace of arsenic or sulphurous acid, whilst with
hydrochloric acid a current of filtered air passed through the
distillate for about 2 hours, by means of a water vacuum-pump,
removes every trace of chlorine, and no trace of arsenic will be
found in the product.
PART VIII.
INTERPRETATION OF THE RESULTS OF ANALYSIS.
WATER.
THE analysis of water, as will have been seen, is not itself a
difficult matter, but great manipulative skill is required, on the
one hand, in order to obtain reliable results, and a thorough
knowledge of the subject of water supply is requisite on the other
in order to discriminate as to the difference between a safe and
an unsafe, a pure and an impure, supply.
The analyst on the brewery premises has not only to deal with
the town or well water supplied to or at the particular brewery
in which he is engaged, but with supplies of all kinds usually
forwarded by the tied or other customers from sources wide
apart. He has, therefore, to be in a position not only to determine
the purity or otherwise, and the saline constituents, but to have
sufficient knowledge of his subject to be able to state with good
reason the nature of the strata through which the water has per-
colated, or whether it is an upland surface water, pure, and likely
to remain so, or whether, on the other hand, it is open to contamina-
tion, and hence to be discarded or looked upon with suspicion.
These are points, like most others pertaining to analyses, which
can only be determined by an analyst possessing a wide and
extensive knowledge, such, as far as water is concerned, as geology
and physics. Besides these, the analyst must know how to
artificially treat different waters in order to render them suitable
for brewing different classes of beer ; hence all that can reasonably
be done in short space is to deal briefly with a subject that in
itself would occupy a good-sized volume.
The primary form of natural water is rain, the chief impurities
in which are traces of organic matter and ammonia derived from
the atmosphere. On reaching the ground it becomes more or less
279
280 THE BREWER'S ANALYST
charged with the soluble constituents of the soil, such as calcic
and magnesic carbonates, potassic and sodic chlorides, and other
salts, which are dissolved, some by a simple solvent action, others
by the agency of carbonic acid in solution. Draining off from
the land, it will speedily find its way to a stream which, in the
earlier part of its course, will probably be free from pollution by
animal matter, except that derived from any manure which may
have been applied to the land on whioh the rain fell. Thus,
comparatively pure, it will furnish to the inhabitants on its banks
a supply of water which, after use, will, in most instances, be
returned to the stream in the form of sewage charged with
impurity derived from animal excreta, soap, household refuse,
etc., the pollution being perhaps lessened by submitting the
sewage to some purifying process such as land irrigation,
filtration, or clarification.
The stream in its subsequent course to the sea will be in
some measure purified by slow oxidation of the organic matter,
and by the absorbent action of vegetation, but not to any great
extent.
Some of the rain will not, however, go directly to a stream, but
sink through the soil to a well. If this be shallow, it may be
considered as merely a pit for the accumulation of drainage from
the immediately surrounding soil which, as the well is in most
cases close to a dwelling, will be almost inevitably charged wibh
excretal and other refuse, so that the water when it reaches the
well will be contaminated with soluble impurities thence derived,
and with nitrites and nitrates resulting from their oxidation.
After use the water from the well will, like the river water, form
sewage, and find its way to a river, or again to the soil, according
to circumstances.
In the case of a deep well from which the surface water is
excluded, the conditions are different. The shaft will usually
pass through an impervious stratum, so that the water entering
it will not be derived from the rain which falls on the area
immediately surrounding its mouth, but from that which falls on
the outcrop of the previous stratum below the impervious one
just mentioned ; and the water of the well will probably be
entirely free from organic impurity or products of decomposition.
But even if the water be polluted at its source, still it must pass
through a very extensive filter before it reaches the well, and its
organic matter will probably be in great measure converted by
oxidation into bodies in themselves innocuous.
This is very briefly the general history of natural waters, and
INTERPRETATION OF THE RESULTS OF ANALYSIS 281
the problem presented to the analyst is to ascertain, as far as
possible, from the quality and quantity of the impurities present,
the previous history of the water, and its present condition and
fitness for the purpose for which it is to be used.
It is impossible to give any fixed rules by which the results
obtained by the foregoing method of analysis should be interpreted.
The analyst must form an independent opinion for each sample
from a consideration of all the results he obtains.
The following classification as to the order of excellence of
waters from different sources is given by Frankland :
(1. Spring water.
2. Deep-well water.
3. Upland surface water.
. . (4. Rain water.
buspicious < .
I 5. Surface water from cultivated lands.
y f 6. River water to which sewage water gains access.
I 7. Shallow- well waters.
Free and Albuminoid Ammonia. In the method of
analysis detailed, Wanklyn endeavours to determine the amount
of organic nitrogen contained in a water by converting it into
ammonia and estimating it as such.
In judging by this process he classifies waters as follows :
Class 1 . Waters of extraordinary organic purity : those yielding
from '00 to '05 part of albuminoid ammonia per million.
Class 2. Safe waters : those yielding from '05 to '10 part of
albuminoid ammonia per million.
Class 3. Impure waters : those yielding more than *10 part
of albuminoid ammonia per million.
1. If the free ammonia exceeds *08 part per million, recent
contamination by urine is indicated. In such case a great excess
of chlorides may be expected.
2. If the free ammonia and chlorine are present in only small
quantity, and if the albuminoid ammonia comes off slowly on
distillation, vegetable contamination is indicated.
3. Unless the albuminoid ammonia exceeds '05 part per
million, a water may be regarded as pure, even though the
proportion of free ammonia and chlorine are large.
4. If free ammonia is present in only small amount, the
albuminoid ammonia is not to be regarded as a reason for con-
demning a sample, unless it reaches '10 part per million.
5. If, however, albuminoid ammonia reaches "10 part per
million, the water is suspicious, apart from the absence of free
282 THE BREWER'S ANALYST
ammonia and chlorine ; whilst if the albuminoid ammonia exceeds
15 part per million, the sample is to be absolutely condemned.
There are few chemists who now altogether accept the whole
of the above statements, since Wanklyn appears to regard vegetable
contamination almost as serious as animal pollution, whereas it
is now generally known that the albuminoids derived from animal
sources are much more dangerous than those derived from
vegetable sources, the reason being that the former are much
more putrescible (i.e. easily decomposable by bacteria) than the
vegetable albuminoids.
It has been stated that by Wanklyn's method the total amount
of nitrogen of the organic matter is never obtained as ammonia ;
that of the various nitrogenous organic substances submitted to
his process some give up the whole of their nitrogen as ammonia,
others two- thirds, some one-fourth, some very little, and others
none whatever. Wanklyn claims, however, that many of the
substances which yield as albuminoid ammonia such varying
percentages of their total nitrogen, never occur in water at all,
and that, adopting the standards he forms, a just judgment of a
water may be always made. This is certainly true, and the
process has become one universally employed by chemists,
particularly as it is less complicated and difficult than others.
In any case a bad water cannot escape the test.
Oxygen absorbed. This test, originally devised by
Forschammer, and known as the " oxygen or Forschammer process,"
was modified by Tidy, to whom we are indebted for its present
application. It is a valuable confirmatory test, and from the
amount of oxygen absorbed it is possible to obtain very useful
information as to the contamination of a water.
Not only organic matter, but nitrates, ferrous iron, and sul-
phuretted hydrogen also absorb oxygen from potassic perman-
ganate, and, as described, corrections for these must be made by a
blank experiment.
Tidy gives the following standards for the valuation of water
by this test, expressing the opinion that " the oxygen absorbed
roughly represents one-tenth of the organic matter present."
1. Waters of great purity, oxygen not to exceed *05 part
per 100,000.
2. Waters of medium purity, not to exceed "15 part per
100,000.
3. Waters of doubtful purity from '15 to '21 part per
100,000.
4 Impure water more than '21 part per 100,000.
INTERPRETATION OF THE RESULTS OF ANALYSIS
283
Tidy particularly protests against the drawing of any
hard-and-fast lines, and gives the classification merely as a
suggestion.
For domestic purposes *-the quantity should not exceed O05
part per 100,000, but anything under 0'25 part per 100,000 in
a water for brewing purposes may be ignored.
Nitrates. The ammonia derived from the atmosphere or
from the putrefaction of organic matter is rapidly oxidised into
nitrous and nitric acids, which combine with one or other of the
alkalies or alkaline earths present in the soil to form correspond-
ing salts. Consequently, although there are several reliable
methods for estimating nitrites and nitrates, there are two ways
of stating the quantity of the latter found on analysis. The
declaration may be as "nitric acid" really nitric anhydride
N 2 5 or as nitrogen existing as nitrates. When stated in the
former, the amount will appear much larger than when stated in
the latter way. The ratio between the two is 14 to 54; con-
sequently, nitrogen as nitrates x 3*86 = nitric acid, and nitric
acid -f- 3 "86 = nitrogen as nitrates. Amounts respectively ex-
pressed in grains per gallon nitric acid are as follows :
Nitrates.
Nitric Acid.
Nitrates.
Nitric Acid.
o-io
0-386
1-30
5-018
0-15
0-579
1-40
5-404
0-20
0-772
1-50
5-790
0-30
1-158
1-60
6-176
0-40
1-544
1-70
6-562
0-50
1-930
1-80
6-948
0-60
2-131
1-90
7-334
0-70
2-702
2-00
7-720
0-80
3-088
2-10
8-166
0-90
3-474
2-20
8-492
1-00
3-860
2-30
8-878
MO
4-246
2-40
9-264
1-20
4-632
Pure waters from different sources contain various amounts
of nitric acid ; spring water contains on an average 2 grains per
gallon and river water 0-57 grain per gallon. A water for
domestic purposes should not contain more than 2 grains per
gallon. For brewing purposes a soft water may contain 2| grains
per gallon, but a hard water may contain up to 4 grains per
gallon ; beyond this, however, difficulties with the yeast, erratic
fermentations, highly coloured beers and frequent instability of
284 THE BREWER'S ANALYST
both yeast and beer, as well as decidedly small outcrops of the
former, is invariably found.
The only remedy against the action of any excessive amount
is vigorous and rapid fermentations, low temperatures, and an
excess of yeast. Finally, however, it must be borne in mind
that the presence of nitric acid in a water may not be due to
the oxidation of organic matter, but to the strata through which
the water has percolated.
In certain districts nitrates exist in the strata, as already
stated, as natural salts, and not as the oxidation products of
contamination. Thus in some of the very pure waters of Kent,
drawn from great depths, to which sewage cannot possibly have
access, considerable quantities of nitric acid are found ; as much
as 4 to 5 grains per gallon being not unusual. The same thing
occurs in certain waters drawn from the new red sandstone, in
some of the gypsum pockets of which nitric acid undoubtedly
exists to the extent of 2 to 6 grains per gallon.
Nitrites. A water showing the presence of nitrites should
always be looked upon with the greatest suspicion, as in most
cases they indicate that organic matter is obtaining access to
the well in quantities beyond those which the adjacent soil,
acting in its capacity as a natural filtering bed, can convert into
the more harmless nitrates. Nitrites have been found in deep
well waters by some chemists; but the author has never yet
discovered them in such waters, and is of opinion that their
presence has been due more to the analytical method adopted
than to the fact of their existence.
Chlorine. When nitric acid is found in excessive quantity
in a water, there is usually a large amount of chlorine also
present. In the neighbourhood of the sea, however, large
amounts of chlorine may exist without being an indication of
organic pollution. A good instance of this is found in the
supplies available for brewing at Yarmouth and other towns close
to the coast. This is due to the atmosphere being laden with
sea salt, which is absorbed by the rain, and thence passes into
the water supplies ; or again, it may arise from the fact that sea
water has percolated through the soil and thus come into direct
contact with the liquor supplies. At Durham, near the coast,
the well waters have often been found to be distinctly saline
owing to this percolation. But the general rule on this matter
runs as follows: If " isochlors " are drawn that is to say, lines
connecting wells of equal depth containing the same amount of
chlorides it is found that, excluding sewage contamination, the
INTERPRETATION OF THE RESULTS OF ANALYSIS 285
further they are situated from the sea the less chlorine do the
wells contain. Some years ago De Chaumont pointed out the
influence of high and low tides on the proportion of chlorides in
a well near a tidal river^. He analysed samples taken from a
well 83 feet deep and situate 2250 feet from the nearest point
of a river in Hampshire. The chlorides fluctuated according
to the state of the tide, ranging from 2*45 grains per gallon
at low water to 2 '8 grains per gallon at high tide. En its
passage through strata containing sodium chloride, water may,
obviously, take up large quantities of chlorides. The triassic
clays of Cheshire, Worcestershire, and other places are rich in
deposits of rock salt, and wells may there be sunk into springs
of brine. And with these deposits of rock salt one often finds
associated the chlorides of magnesium and potassium, besides
frequent occurrence of gypsum.
Urine, which contains nearly 1 per cent, of sodium chloride, is
a frequent source of pollution ; consequently, a water containing
a much larger amount of this salt than other waters occurring
in the same district, and which are known to be uncontaminated
by sewage, is to be regarded with suspicion. A fairly large
amount of a highly nitrogenous substance called "urea" is also
present in urine, and this, under the influence of bacteria, is
rapidly transformed into ammonium carbonate; consequently,
waters directly polluted by urine contain considerable amounts
of free ammonia as well as chlorides. The drainage from sewers,
middens, and cesspools are rich in both chlorine and ammonia, and
as the latter is also one of the chief compounds derived from the
decomposition of animal organic matter, its presence in the water
of shallow wells often points to recent pollution with organic
matters of animal origin. It will thus be seen that in judging the
organic contamination of water the whole of the foregoing data
must be conjointly considered before a true estimate can be made.
Saline Constituents. The total saline bodies in all waters
depend upon the strata receiving the rainfall and through which
the rain percolates.
Of the saline bodies which are more or less soluble in water, and
which are therefore taken up by the rain water in percolating
through the various porous strata, mention may be made to
calcic carbonate, calcic sulphate and calcic magnesic and sodic
chloride, familiar to us in the mountain limestones of Derbyshire
and the marls of Cheshire and Staffordshire,
The great masses of mountain limestone and dolomite or
magnesian limestone have a very important influence upon the
286 THE BREWER'S ANALYST
waters passing over and through them. The carbonic acid taken
into solution by the rain water in falling through the atmosphere
and from the surface soil enables this water to dissolve these
rocks and take into solution carbonates of calcium and magnesium
and small quantities of carbonates of iron and manganese. Other
acids, occurring in small quantities in rain water, also act on these
rocks and pass into the ground in solution as salts of calcium or
magnesium, etc. Chlorides, sulphates, and nitrates of alkalies
sodium and potassium may be taken into solution, and almost
invariably small quantities of silica and alumina. Iron pyrites
by oxidation and decomposition supplies sulphuric acid which,
reacting with the carbonates, yield sulphates even when gypsum
is not found in the soil.
Dr Parkes 1 classifies waters according to their hardness as
follows :
1. Waters from Granitic Metamorphic Trap-rock
and Clay Slate. The total solids usually very low, not
exceeding 6 grains per gallon ; they consist of carbonate and
chloride of sodium, with very little lime and magnesia. The
quantity of organic matter small.
2. Millstone Grit and Hard Oolite Waters. These
resemble the waters just described ; they are very pure, and
contain carbonate and sulphate of lime, magnesia, and traces of
iron; the solids seldom exceed 8 grains per gallon.
3. Soft Sand-rock Waters. Waters derived from this
source are frequently impure, and contain much chloride,
sulphate, and carbonate of sodium, with but little lime and
magnesia. The total solids range from 30 to 80 grains per
gallon, and the organic matter is also very high. Occasionally
these waters are found pure and soft.
4. Loose Sand and Gravel Waters. Composition extremely
variable ; solids ranging from 4 to 70 grains per gallon ; reaction
of water often strongly alkaline, and the organic matter somewhat
high. A few are very pure, notably those from the greensand,
where extreme purity is sometimes found.
5. Lias Clay Waters. Frequently contain very large quan-
tities of mineral matter ; as much, even, as 200 grains per gallon.
6. Chalk Waters. These, representing a very large and most
useful class, are usually of fair, and sometimes of great, purity,
and contain from 5 to 25 grains per gallon of carbonate of lime.
7. Limestone and Magnesian Limestone. These resemble
in many respects chalk waters, but contain large quantities of
1 Practical Hygiene.
INTERPRETATION OF THE RESULTS OF ANALYSIS 287
magnesia and lime, which exist generally as sulphate. Sometimes
they are of great purity.
8. Senelic Waters. Rich in sulphate of lime, and generally
very hard, but often of great purity.
9. Surface and Subsoil Waters. These of course vary
enormously in composition, but are mostly impure, almost invari-
ably so in populated districts.
10. Marsh and Moor Waters. These are often extremely
soft, many moor waters containing a solid residue not exceeding
5 grains per gallon.
Marsh waters are very rich in organic matter ; but this is of
little importance, as it is usually of a vegetable character.
Moor waters are very similar, but contain less organic matter,
are indeed sometimes very pure. They generally have a peculiar
earthy or peaty smell, and are of a slightly yellowish tint.
The saline bodies in ordinary waters vary from about 2 to 80
or even 250 grains per gallon, and waters are distinguished as hard
and soft according as they contain large or small quantities of
lime or magnesia salts in solution. These may exist either as
carbonates held in solution by carbonic acid, or as sulphates. In
both cases the water is hard : that is, it requires much soap to be
used in order to make a lather, because an insoluble compound is
formed by the union of the lime or magnesia with the fatty acid
of the soap. The hardness, however, is of two distinct kinds,
namely, " temporary " and "permanent."
Temporary hardness is due to the solution of carbonates of lime
and magnesia which may be precipitated on boiling; whilst
permanent hardness is due to the presence of unprecipitable bodies,
namely, the sulphates of those bases.
Let us now look at the difference in the character and quantity
of the saline constituents in what is known to the brewer as hard
and soft waters.
The following is a typical analysis of water drawn from the
new red sandstone (Keuper) at Burton-on-Trent.
1. BURTON WATER (HARD).
Calcic sulphate . . . .77*89
Calcic carbonate . . . 6*80
Magnesic carbonate . . . 20'29
Sodic chloride . . . 2 '60
Potassic sulphate . . 1'73
Sodic nitrate . . . 1 '32
Total saline bodies . 110 '63 grains per gallon.
288 THE BREWER'S ANALYST
In this and similar waters the calcic sulphate is the chief
constituent, the best effect for pale-ale production being provided
with waters containing from 50 to 75 grains per gallon. It will
be noted that the chlorides are very small in quantity, and
although the magnesic carbonate is very high, yet it would be
almost entirely precipitated on boiling.
2. DUBLIN WATER (SOFT).
Calcic sulphate .... 4*40
Calcic carbonate . . 14*30
Magnesic carbonate . . . 1'18
Sodic chloride . . . T73
Iron oxide and alumina . . 1*14
Silica -12
Total saline bodies . 2 2 '87 grains per gallon.
This and similar waters are characteristic for the small amount
of saline bodies, excepting calcic carbonate, which they contain.
Even this salt, as well as magnesic carbonate, is almost entirely
precipitated on boiling, so that practically the amount of saline
bodies which enter the mash total about six grains per gallon.
Such waters are renowned for black-beer production.
3. MEDIUM WATERS.
Calcic sulphate . . . . 6 '25
Calcic carbonate . . . 16'24
Magnesic carbonate . . . 4*14
Sodic chloride . . .35-12
Calcic chloride . . . " . 3'88
Iron oxide and alumina . . 0*22
Silica 0-26
Total saline bodies . 66'11 grains per gallon.
The characteristic property of these waters is the large quantity
of chlorides which they contain, and which renders them
particularly suitable for mild-ale production.
Other typical waters rich in chlorides are the following :
4. EDINBURGH WATERS.
Calcic and magnesic carbonates . 19 '86 33*74
Calcic and magnesic sulphates . 6*59 9'76
Sodic and potassic chlorides . . 14*57 18*34
Magnesic chloride . . . ... 2' 13
Total saline bodies . .41-02 63-97 grainsper gallon.
INTERPRETATION OF THE RESULTS OF ANALYSIS 289
The carbonates of these waters are also almost entirely pre-
cipitated on boiling; the chlorides, which like the former water
(No. 3) are excessive, are undoubtedly of advantage in giving the
decidedly full flavour to all mild beers produced by their aid.
5. CHALK WATERS.
Calcic and magnesic carbonate . 13 '60
Calcic sulphate . . . . 1'23
Calcic chloride . . . 1'32
Magnesic nitrate . ' . "41
Total saline bodies . 16'56 grains per gallon.
The above is an example of pure chalk waters such as is
obtained from the chalky strata of the south of England and
numerous other districts.
6. LONDON WATERS.
(Derived from the greensand below the London clay.)
Calcic carbonate . . . 6-83
Magnesic carbonate . . . 1*73
Sodic chloride .... 10'89
Sodic sulphate .... 14-36
Sodic carbonate . . . 10 '31
Silica and alumina . . . '36
Iron oxide .... -48
Total saline bodies . 44'96 grains per gallon.
From these waters the black beers for which London has so
long been celebrated are brewed. The sodic chloride, which is in
considerable proportion, and also the presence of sodic sulphate,
will be noted. Such waters are unsatisfactory for pale-ale
production, and it is impossible to artificially manipulate them for
this purpose, since after such treatment the chlorides are excessive.
It will be seen, then, that water No. I is excellent for pale-
ale production, but would require to be artificially treated for
the production of mild ale or stout ; that waters Nos. 2 and 6
are excellent for stout, but would require to be artificially
treated for the production of pale and mild ales; that waters
Nos. 3 and 4 are excellent for mild ales, but would require
manipulating when producing pale ales or stout; that water
No. 5 requires artificial manipulation for the production of pale
19
290 THE BREWER'S ANALYST
and mild ales, but without treatment is a good water for stout
brewing ; whilst water No. 6 is unsuitable for pale ale, artificial
treatment being of no avail.
All the foregoing waters, excepting Xos. 1 and 6, readily lend
themselves to artificial treatment, so that any kind of pale, mild,
or black beer may be produced.
Artificial Saline Manipulation. From what has gone
before and from general knowledge of the facts :
(1) That the finest pale ales produced in this kingdom are
those manufactured from hard waters such as are found at
Burton ;
(2) That the finest black beers are produced by the aid of
extremely soft waters such as are found at Dublin ;
(3) That the finest mild ales are obtained by the use of inter-
mediate waters containing an excess of chlorides, which are
common in many parts of the kingdom;
it follows, almost without saying, that as no firm of brewers
possesses the desired respective waters, it becomes necessary to
artificially treat the supply for one or other or all beers.
In copying the saline character of any special water, we have
therefore to add the salts in which our supply is deficient, and
sometimes decompose salts which naturally exist ; or, if our
supply is excessively saline, first dilute it before carrying out
either.
An excessively saline water is therefore either diluted by the
addition of a pure supply, such as that employed for domestic
purposes, or it is boiled for a considerable time by blowing in
naked steam.
All good brewing waters should contain at least 6 grains per
gallon of calcic carbonate. There is no proof that there is any
advantage in the presence of more, but it is a fact that some of
the best brewing waters contain a far larger proportion.
If, in the production of bitter beers, it is desired to harden the
water, assuming it contains an excessive quantity of earthy
carbonates, a portion of them may be converted into sulphites by
the addition of sulphurous acid, thus :
H. 2 S0 3 + CaCO 3 = CaS0 3 + OH 2 + C0 2 .
H 2 S0 3 + MgC0 3 = MgS0 3 + OH 2 + C0 2 .
On the other hand, if such carbonates exist in the liquor in
sufficient quantity, the water may be hardened by the addition of
sulphate of lime or, what is practically the same, gypsum.
The most suitable amount of sulphate of lime in a water for
INTERPRETATION OF THE RESULTS OF ANALYSIS 291
"stock" pale ales is 75 grains per gallon, but for running bitters
required to drop brilliant in quick time 30 grains is more pre-
ferable. In no instance should the former amount be overstepped,
since, if so, beers will be- slow in coming into condition and
in dropping bright.
With regard to sulphate of magnesia, practical experience has
shown that the quantity should not exceed one- third that of the
sulphate of lime present. If present in large excess, it promotes
a tendency to fretfulness and results in thin drinking beers.
Taking the chlorides as next in order, their influence in impart-
ing fulness to beers has long been known ; and it is now generally
acknowledged that chlorides of calcium and magnesium alone, or
more particularly in conjunction with those of sodium and
potassium, determine a full and rich flavour. A proportion of
chlorides which might be expected to give marked results would
be about 7 or 8 grains of calcic chloride, the same quantity of
magnesic chloride, 10 grains of potassic chloride, and 8 of sodic
chloride per gallon.
The sulphates and carbonates of the alkalies, if present in excess
in a brewing water, are decidedly objectionable, even for stout or
porter production, for which they were once thought desirable.
They extract colouring matter from the materials employed
during mashing, and also a rank, bitter flavour from the hops
during boiling. They also act upon the nitrogenous bodies by
reason of their tendency to neutralise the acidity of the wort, and
in consequence prevent any peptonising influence. In order to
decompose such objectionable bodies, treatment with chloride of
calcium is resorted to, thus :
CaCl 2 + Na 2 S0 4 = CaS0 4 + 2 NaCl.
CaCl 2 + K 2 S0 4 = CaS0 4 + 2 KC1.
CaCl 2 + Na 2 C0 3 = CaCO 3 + 2 NaCl.
Ca01 2 + K 2 CQ 3 = CaC0 3 + 2 KOI.
So that in each case useful salts are produced from the injurious
ones naturally present.
From the first example we see that, by the addition of chloride
of calcium to a water containing sulphate of soda, we get a
reaction resulting in their decomposition and the formation of
two fresh compounds. It should be borne in mind, however,
that by the use of chloride of calcium to decompose sulphates
and carbonates of soda or potash, the amount of resulting chlorides
is usually so large that, as previously stated, a high-class pale ale
can seldom be produced.
292 THE BREWEK'S ANALYST
The commercial salts usually contain varying percentages of
moisture, so that allowance must be made in this direction when
artificially treating water.
The following is a list of the salts usually employed in water
manipulation, showing their quantities in the anhydrous form ;
also the percentage of moisture and actual salt :
Commercial Salt.
Anhydrous M ^ Ure
oU
Per-
centage
ACtU.3.1
Calcic sulphate
CaS0 4 +
2
OH 2 =
172
136
centage.
20-93
Salt.
79-07
(gypsum)
Calcic chloride
CaCl 2 +
6
OH 2 =
219
111
49
31
80
69
Magnesic sulphate
MgS0 4 +
7
OH 2 =
246
120
51
21
48
79
(Epsom salt)
Magnesic chloride
MgCl 2 +
6
OH 2 =
203
95
53
20
46
80
Sodic carbonate .
Na 2 C0 3 +
10
OH 2 =
286
106
62
93
37
07
Potassic ,,
K 2 C0 3 +
2
OH 2 =
174
138
20
68
79
32
Sodic chloride
NaCl
=
58-5
(common salt)
Calcic carbonate .
CaCCL
=
100
An example of the above being :
CaS0 4 + 2 OH 2
Ca= 40 + 0=32
S= 32 H= 4
0= 64
136 36
\/
172 : 36 ;: 100 : 20'93 per cent, moisture.
100-00 - 20-93 = 79-07 per cent, actual salt.
CaS0 4 .
In cases where it is first necessary to decompose the salts
already existing in the water, facts similar to the following have
to be taken into consideration :
From the foregoing table we see that the equivalent of anhy-
drous calcic sulphate is 136; by dividing this figure into the
weight of any commercial salt with which it will combine, we
arrive at the quantity of the salt necessary to be added to the
water in order to effect decomposition of the existing salt, viz.,
calcic sulphate in a water = 136, which divided by sodic carbonate
commercial 286 = 2'10 grains per gallon. In other words, every
INTERPRETATION OF THE RESULTS OF ANALYSIS 293
grain of calcic sulphate in the water will require for its decom-
position 2-10 grains of sodic carbonate. Similarly-
Calcic sulphate 136 ^ potassic carbonate 174 = 1'28.
Magnesic sulphate 120^ sodic carbonate 286 = 2'37.
Potassic carbonate 174-f-rnagnesic sulphate 120 = 1 '45.
The following table shows the reactions and the quantities of
salts required to effect decomposition :
Every
Grain per ^
gallon of .
CaS0 4 requires 2'10 grains Na 2 C0 3 to produce Na 2 S0 4 + CaC0 3 .
CaSO 4 1-28 K 2 C0 3 K 2 S0 4 +CaC0 3 .
MgS0 4 2-37 Na 2 C0 8 Na 2 S0 4 + MgC0 3 .
MgS0 4 1-45 K 2 C0 3 K 2 S0 4 + MgC0 3 .
Na 2 S0 4 1-20 CaCl 2 ., CaS0 4 + 2 NaCl.
K 2 S0 4 1-50 CaCl 2 CaS0 4 + 2 KC1.
K 2 C0 3 1-20 CaCl 2 CaC0 8 +2 KC1.
Na 2 CO, I'OO grain CaCl a CaC0 8 +2NaCl.
All that is necessary is to multiply the number of grains per gallon
of each of the salts in a water by the corresponding figures given
in the column marked *, and the result will be the total amount
(grains) of the respective anhydrous salts to be added to each
gallon of the water in order to effect a mutual exchange between
the acids and bases. If, then,, by these means we completely
change the character of a water, knowing the amounts and
character of the salts existing after treatment, we may then, if
necessary, add any further salts desired.
Owing to calcic chloride being a very deliquescent salt, and in
consequence somewhat difficult to handle, it is often purchased in
the form of a saturated solution, which has a specific gravity of
about 1380.
A specific gravity equal to 1379*7 equals 38 per cent, of calcic
chloride (CaCl 2 ) in solution. This figure is per cent, by weight ;
so that to get per cent, weight on volume in order that the
solution can be measured instead of weighed it becomes necessary
to multiply 38 by the gravity divided by 1000, i.e. 38 x 1-3797 =
5 2 '4 per cent. Hence a pint of this solution containing 20 fluid
ounces contains 52 '4 per cent, of 20, or just over 10, ounces by
weight of calcic chloride. Therefore a twentieth of a pint to a
barrel equals practically half an ounce, or, to be exact, 2 '2 9 grains,
equivalent to just over 6 grains per gallon of calcic chloride. In
like manner the grains per gallon it required to communicate
294 THE BREWER'S ANALYST
to a water can be worked out upon knowing the specific gravity
of the solution.
Biological Examination of Water. Water is very
absorbent; whether it be the water of rivers, lakes, ponds, or
that in public reservoirs, it readily absorbs gases and receives
the floating particles of the atmosphere, commonly called " dust,"
but which constitute for the most part " germs," which in many
cases only require moisture to bring out their vitality.
No kind of water, whether running or standing, is devoid of
bacteria, and the waters of rivers usually contain many more
organisms than that of lakes or large reservoirs. Some species of
bacteria are confined to foul or contaminated waters containing
decaying animal and vegetable matter only, such as pools on
moorlands, dirty ditches, canals, docks, etc. ; and from this it is
inferred that it is not only possible, but that it will help us in
time to come, when our knowledge of bacteriology becomes more
extended, to connect particular forms with particular kinds of
water and with particular sources of contamination.
In some cases it is found that there are forms of bacteria in a
water which are not typically characteristic of water at all, but
are pathogenic species, which have been introduced with foreign
matter ; these cases are, however, rare.
As the rain water percolates through the strata, more or less of
it soon sinks to levels below those at which there is danger of it
emerging as a contaminated fluid, and in this process of percola-
tion other important changes take place besides those already
enumerated.
As the water passes from the surface soil to the subsoil, it is
to a great extent deprived of its dissolved oxygen, and a large
portion of its suspended germs are held back in the capillary
interspaces. In the subsoil the water is in contact with bacteria
of quite a different nature from those in the well-aerated surface
soils rich in organic and other food supplies. These anaerobic
organisms of the deeper layers are not necessarily less injurious
or otherwise than the aerobic forms in the surface soil, but far too
little is known about them to say much as to the comparison.
Water examined at the source of deep springs, or in the deep
subterranean layers tapped by artesian well-pipes, is found to be
wholly or practically free from organisms at or near the surface.
Moreover, it is an axiom that, in cases where the water supply is
drawn from rivers, there are more bacteria as we go towards the
mouth, and fewer as we ascend the heights of the watershed ;
whilst the gain in bacteria, both as regards forms and numbers
INTEEPEETATION OF THE RESULTS OF ANALYSIS 295
of individuals, is marked below each town or inhabited area
through which the river flows.
It is obvious that the process of water examination, described in
Part IX., enables us to investigate the subject further than is
possible by purely chemical analysis, as described in Part VI.
By determining the number of micro-organisms present in water
before any system of purification, we are enabled to see how far
it is contaminated by such organisms ; whilst if we subject water
to filtration, we are not only thus in a position to test the efficiency
of our filters, but to keep a watch on the same, any undue
proportion of micro-organisms making their appearance in the
filtered water proving at once that the filters are not acting, and
that either the filtering material requires to be renewed or cleansed.
According to Schwacktiofer, who bases his opinion on a
large number of analyses of brewing waters conducted by the
meat-gelatine plate-cultivation process (p. 369), a water may be
classed as good so long as it does not contain more than 6120
colonies per c.c. ; unfavourable from 6120 up to 8456 per c.c. ;
permissible from 8456 up to 46,700 per c.c. ; and beyond this
bad. This of course does not consider the question of contami-
nation from pathogenic organisms, the appearance of even one
such germ being more than sufficient to condemn the supply.
According to Hansen, a water is held to be a satisfactory one
if, when examined by his method (p. 372), the wort to which it
has been added remains clear after three days' exposure to a
temperature of 90 F. (32'2 C.).
In the author's opinion Hansen's method is an excellent one for
testing aerial organisms, that is to say, for testing the number of
organisms present on any particular occasion in the atmosphere
capable of developing in wort, yeast, or beer ; but his statement,
" The vast amount of organisms found in water have no significance
whatever for the brewer, as very few are capable of vegetating in
either wort or beer" must be accepted with great reservation. We
know perfectly well, as the author was the first to show, 1 that
absolute sterilisation of wort is effected during boiling in the
copper, and that the significance of organisms is their growth in
wort after boiling, and in yeast and beer ; but we are aware that
even such organisms as have been destroyed by sterilisation,
or that do not grow in wort, yeast, or beer, and thus suffer
destruction, are, though dead, left in the wort, yeast, or
beer, and act as food or toxins for other organisms. In any case,
therefore, it is, in the author's opinion, advisable to remove them
1 Brewing Trade Review, 1st July 1889, 228.
296 THE BREWER'S ANALYST
from a water by filtration, provided they are present in great
numbers.
Finally, a water unduly charged with micro-organisms cannot
flow into a brewery or malt-house and be used for even cleansing
purposes without sowing seeds for bacterial growths in every
direction.
SULPHITES.
The sulphites and " bi " or acid sulphites offered to the brewer
are usually of great purity and strength, and no longer the
inferior varieties which were not uncommonly manufactured and
met with some fifteen or twenty years ago. The oldest and perhaps
still the best of these is bisulphite of lime, and although this
has to some extent been discarded for the more conveniently
handled solid sulphites, it is nevertheless believed by many to be
superior, and certainly has advantages in the sense that it is a
valuable antiseptic for washing fermenting vessels and other
brewery plant, as well as acting as a germicide when added to
beer or to the sprinkling water used during malting.
It is usually sent out at a specific gravity of 1065, but may
of course be obtained at greater strength, such as 1075, or even
up to 114:0. If of a higher specific gravity than 1065, it rapidly
loses its strength on storage owing to the extreme liability of
sulphur dioxide to volatilise, so that it is questionable whether it
is not more advisable to purchase at the lower strength. In any
case, the lower strength is sufficient for all brewery purposes.
Bisulphite of a strength of 1065 should contain not less than
6 per cent, total sulphurous acid, one-half of which should exist
in the free state. Most samples contain sulphate of lime, but
in carefully prepared samples the amount of this should be less
than 0-5 per cent. Traces of magnesia and chlorides of the
alkalies are usually present, but exert no deleterious influence.
Any sample showing the presence of hyposulphites should be
discarded as unfit for use.
Sulphurous acid is manufactured by heating coke which has
been moistened with sulphuric acid, or by boiling sulphuric acid
in the presence of sulphur in a boiler similar to a steam boiler.
The sulphurous fumes evolved are then passed through a washing
apparatus, where they are purified and condensed.
In the manufacture of bisulphite of lime the purified and
condensed acid is conducted into a series of lead-lined tanks, or
casks containing milk of lime.
Sulphite, and afterwards bisulphite, of lime is thus produced.
INTERPRETATION OF THE RESULTS OF ANALYSIS 29?
Sulphites of soda and potash are also largely used, but are
very prone to decompose during storage, sulphate of soda on
the one hand, and sulphate of potash on the other, being formed.
Besides the sulphites and the bisulphites, a series of salts have
long been prepared which are known as the " metabisulphites,"
also sometimes called pyrosulphites and disulphites. Thus we
have potassium metabisulphite, kalium metasulphite, etc.
Kalium metasulphite is prepared by passing sulphur dioxide
into a hot saturated solution of potassium carbonate (Muspratt),
or into a mixture of milk of lime and potassium sulphite (Boake
Roberts).
The crystals with difficulty dissolve in water, and have an acrid,
unpleasant taste. Many years ago Boake Roberts obtained a
patent for mixing the crystals with a gummy substance and
compressing certain quantities into " tabloids " ; the patent, how-
ever, has expired, and the word "tabloid" is now the exclusive
property of Burroughs Wellcome & Co.
The value of the sulphites, bisulphites, and metasulphites
to the brewer depends upon their decomposition by acids. When
the beer to which these materials are added develops acidity,
the sulphites are decomposed, the liberated sulphurous acid
effecting the destruction or oxidation of the organic matter
and thus preventing putrefaction. In other words, any disease
organisms which make their appearance (lactic, butyric, etc.)
are oxidised and destroyed before they have time to multiply.
BARLEY AND MALT.
BARLEY.
Weight. The weight of a good two-rowed barley varies from
49 to 58 Ibs. per bushel, the best averaging from 53 to 58 Ibs. j
while six-rowed bere or big, having a thick husk, usually weighs
from 49 to 51 Ibs. per bushel ; and foreign varieties proportionately
less in comparison to their greater proportion of husk. Much
importance was formerly attached to the weight, but provided
the same essential characters are present, that is to say, provided
the grain is not damp, that it is comparatively free from extraneous
bodies, that the corns are of equal size and colour, that there are
no dead, sprouted, or weathered corns, and that the odour is good,
light barley will yield equally good malt. This is especially the
case with the foreign barleys, although it must be remembered
that the starch content is less in foreign grain ; and as the
298 THE BREWER'S ANALYST
extract obtainable from barley, or the malt made from it, depends
upon its quantity of starch, this must be reckoned with when
purchasing.
Starch. As a rule barley contains from 60 to 66 per cent, of
its weight of starch.
PPOteidS OP Albuminoids. Steely barleys generally have
a high nitrogen content, or, in other words, possess a large per-
centage of proteids or albuminoids. Barley with a moisture
content of 15 per cent, (which may be taken as an average) con-
tains from 1 to 2*5 per cent, of nitrogen, equal to from 6 to 16
per cent, albuminoids.
An excess of nitrogenous matter displaces more or less soluble
or hydrolysable carbohydrate matter of the endosperm. There is
therefore loss of extract, because the greater part of the nitro-
genous matter is not available as extract.
Barleys of high nitrogen content, say from 1 '8 per cent, upwards
(=11 per cent, albuminoids), are generally difficult to modify
unless forced, which means loss of material by undue respiration.
The difference in amount of extract, calculated on the barley,
even if there were no loss due to increased respiration or imperfect
modification, may be considerable. Take extreme cases, with a
barley containing 2 per cent, of nitrogen (12 per cent, albuminoids) :
for every 100 Ibs. of barley there will be, roughly, 12 per cent,
of nitrogenous matter, of which not more than 2J per cent, will
be found in the boiled extract from the malt; the remainder,
9J Ibs. or more, will be found partly in the rootlets of the
malt, partly in the spent grains, and partly in the matter
separated on boiling. On the other hand, with grain con-
taining only 1 per cent, of nitrogen, equal to 6 Ibs. of nitro-
genous matter per 100 Ibs. of barley, about 1J Ibs. of nitrogenous
matter may be found in the malt extract after boiling, and only
4J Ibs. lost.
It is to be understood that these are extreme cases, neither as
low a nitrogen percentage as 1 nor as high as 2 (6 to 1 2 per cent,
albuminoids) being very common. But, on the other hand,
barleys with 1 and 2 per cent, respectively of nitrogen will never
be alike in other respects. The 1 per cent, barley may be a
very thin, husky grain, and the low nitrogen content be
^due to excess of husk, which contains less than half as much
nitrogenous matter as does an equal weight of endosperm ;
whilst grain of good size, but very thin husk such as a
line sample of Chevallier Chilian may have a relatively high
nitrogen content.
INTERPRETATION OF THE RESULTS OF ANALYSIS 299
We thus see that 80 to 85 per cent, of the nitrogenous matter
in barley is insoluble ; but nitrogen content alone is only useful as
an index of quality for comparing barleys which are in other
respects approximately alike, and all we can say is that barleys
of high nitrogen content will necessarily, when converted into
malt, give a lower extract to the extent that proteid matter
displaces available carbohydrate matter, and that also nearly
always the barley will be steely, and require to be so malted as
to cause undue rootlet growth and undue loss by respiration.
In the author's opinion barley should not contain more than
1 1 per cent, of nitrogenous substances, or forcing during malting
becomes necessary.
Acidity. An aqueous extract of barley is always more or less
acid ; and this, like the acidity of malt, was formerly attributed to
the presence of lactic acid. It is now universally agreed, however,
that the acidity is mainly due to primary arid acid phosphates, and
in a less degree to volatile and fixed organic acids.
The respective proportions of these bodies in two samples of
barley, expressed in percentages of lactic acid on the water-free
substance, are given by Prior as follows :
1 2
Volatile organic acids . . . 0'07 0'05
Fixed organic acids .... 0*06 0*05
Primary phosphates .... 0'29 O25
0-42 0-35
It has not yet been proved that an excess of acidity is detri-
mental or otherwise, and the test, so far as barley is concerned, is
of little use.
Mineral Matters. On incineration, barley leaves a residue
or ash of from 2'5 to 3'0 per cent., reckoned on the dry substance.
This ash, expressed as percentage on the ash, consists approximately
of the following mineral matters :
Potassium 20-92
Sodium 2-39
Lime . 2-64
Magnesia ...... 8'83
Iron oxide . . . . . .1*19 ^
Phosphoric acid . . . . .35*10
Sulphuric anhydride ....... . . 1'80
Silica 25-91
Chlorine 1-02
300 THE BREWER'S ANALYST
The potassium and magnesium phosphates are the most
important, since they supply the mineral food for the yeast.
Moisture. The average amount of moisture in British barleys
in good harvest seasons varies from 12 to 18 per cent., and in wet
seasons may run as high as 25 per cent. ; the average, however,
may be taken as 15 per cent., and barley containing over 20 per
cent, may be considered damp.
With foreign barleys the moisture is frequently as low as 7 and
seldom more than 12 per cent.
Physical Examination. There can be no doubt that the
chemical examination of barley, as described in Part VI., is of
considerable importance ; and although, from a botanical point of
view, a great deal of work has been performed and much light
thrown upon the cereal, nevertheless it must be admitted that
the analyst has fought shy of examining it. The time is now
ripe, however, for a more complete chemical analysis than we at
present possess, and in the near future more will be known of the
character of barley and its use in malting and brewing. We
know that the translocation diastase varies approximately pari
paxsu with the total nitrogen with barleys grown under parallel
conditions, and that the enzyme forms products by its action on
starch paste which are quite different from those produced by
malt diastase. We have also ample evidence that differences are
exhibited in the starch of different barleys, and are no doubt
explicable by the conditions of growth, harvesting, and the ripe-
ness of the grain. We can only as yet, however, surmise that
these differences are due to the latter conditions ; and from these
facts it behoves chemists to attack these questions with vigour,
and bring to light more facts regarding the constituents of barley
and their action during the growth of the grain during malting
and as existing in finished malt. Barley when offered for sale to
the brewer or maltster has always been threshed from the straw
and separated from the awns, and in judging the quality the
following points have more or less to be carefully considered :
(1) Mould : whether derived from held, stack, or granary.
(2) Odour.
(3) Bittenness : the ravages of insects or vermin.
(4) Dirtiness : occasioned by the presence of dust, dirt, stones,
string, metal, or other so-termed rubbish.
(5) Threshing influences : brokenness, the damage arising from
threshing, hummelling, or dressing upon germ or kernel. The
presence or absence of awns : if present, to what extent ; if absent,
to any detrimental closeness.
INTERPRETATION OF THE RESULTS OF ANALYSIS 301
(6) Condition of endosperm : mealiness, softness, colour as
distinct from colour of skin, steeliness.
(7) Size : uniformity.
(8) Colour : uniformity.
(9) Moisture.
(10) The influences derived from weathering or imperfect
sweating in stack.
It is not within the range of the present work to deal with
these matters in extenso, but rather with the points of analysis, so
we must leave these subjects, sufficing it to say that it must be
obvious to all that highly important and absolutely essential as
is a true evaluation of barley from a physical examination, this
should be supplemented in very many instances by chemical
analysis, the question of nitrogen content alone being sufficient to
guide one as to the method of procedure during malting.
MALT.
Weight. The weight of pale malt from British barley varies
from 38 to 44 Ibs. per bushel, and more highly dried and foreign
varieties proportionately less. The heavier the malt, provided it
possesses the other necessary qualities, the more the extract
obtainable. Care should be exercised, however, to see that the
malt does not derive this quality from imperfectly vegetated or
steely corns, which are naturally heavier than those of a friable
nature.
Extract. The laboratory extract of malt depends largely
upon the system of grinding whether coarse or ground to powder.
By means of the Seek mill (fig. 70, p. 196) a standard system may
be employed and comparisons the better understood. By grinding
in the Seek mill set at 25, any average pale British malt gives a
laboratory extract of from 93 to 96 Ibs. per standard quarter.
Mild ale malts should show from 90 to 94 Ibs., and foreign grain
according to its character. Fine samples of Californian in
exceptional cases may show up to 92 Ibs., but 86 to 90 is more
usual. Smyrnas' are a little lower ; Tripolis', Tunisians' and the
like from 83 to 85; and Ouchacks' from 83 to 91, the former
being more usual owing to the difficulty of getting such material
thoroughly modified.
Saeeharification Period. It is understood by this test that
the shorter the period taken for the starch to disappear, the
better the modification of the malt. It is a test of some import-
ance, in so far as it shows that in cases where the diastafcic power
302 THE BREWER'S ANALYST
is found to be high, the saccharification of the malt is accomplished
in quicker time, and hence the saccharification period and the
diastatic power have some connection. There is, however, a
dislike for any quantitative method which depends essentially
upon a starch test when there is much carbohydrate matter
present which is similar to starch, and on the whole the signi-
ficance of the test lies only in the corroboration it affords the
more exact and important test for diastatic power as devised by
Lintner.
Specific Rotatory Power of Wort. The value of this test
is best explained in the words of Heron, who states
" In my opinion the specific rotatory power of the hot mash is
a very useful factor in the examination of malt, as giving some
idea of the relative ratios of dextrin to maltose. I find that a
wort which gives a specific rotatory power of [a] D = 116 shows a
dextrin maltose ratio of about 1 : 3, and these are generally the
conditions which govern the brewing of pale and stock ales, whilst
for mild and running ales a specific rotatory power of [] D = HO
is usually found to be advisable.
"Mashing with the same malt and under the same conditions,
the brewer will find that the same polarimetric results are
obtained day after day. From this it will be seen how extremely
advisable it is to make a polarimetrio examination of each lot of
fresh malt in the laboratory before proceeding to use it on the
large scale in the brewery, for if the brewer when examining his
wort obtains a lower [a] D than usual, it serves as an indication
that something must be done to restore it to the normal, either
by raising his striking heat or blending this malt with another
which gives a higher [a] D than the usual, and thereby bring about
a normal condition of things ; otherwise variations in attenuation
and trouble in fermentation and cask conditioning may arise.
" It is usual nowadays not to brew from one single class of malt,
but to use a blend of two or more different kinds, generally
English, with one or two foreign varieties. It will be found
extremely useful to make a preliminary mash on the small scale
of each of such malts, and determine the [a] D of each before
using them in the brewery."
In order to make this test of value, it is absolutely essential
that the temperature of the mash throughout should be the same
with each class of malt operated upon, since slight fluctuations of
temperature cause considerable difference in the specific rotatory
power. The same remarks apply with even greater force to the
cupric oxide reducing power, so that both these, whether expressed
INTERPRETATION OF THE RESULTS OF ANALYSIS 303
as maltose, dextrin ratio, or otherwise, are only of value when
the conditions of temperature are constant.
Acidity. Formerly the acidity of malt was attributed to the
presence of lactic acid, but it is now quite a moot point whether
lactic acid exists in normal malt, it being almost universally
agreed that the acidity of malt is due, as Prior has shown, 1 to
primary or acid phosphates, and in a less degree to volatile and
fixed organic acids.
During the early period of the germination of barley the
volatile acids remain about the same, or may increase somewhat,
whilst the fixed organic acids suffer a perceptible diminution ;
this diminution is concurrent with a proportionate increase of
primary phosphates, the explanation being that the fixed organic
acids react with the secondary and tertiary phosphates of
potassium, magnesium, and calcium, giving rise to primary
phosphates and salts of the organic acids.
The normal proportion of free acid in malt is from 0'2 to 0'3
per cent., expressed in terms of lactic acid, and it should not
exceed 0'4 per cent.
Although a high acidity in malt is suspicious, many of the
worst malts possess but little. High-kilning temperatures tend
to increase acidity, the acid arising from the destruction or
caramelisation of organic matter. A badly stored malt always
shows a high moisture percentage, and. commonly with this a
high acidity. It must be remembered, however, that malt just
off the kiln may, from imperfect kilning, contain an excess of
moisture, and the acidity may be low.
Although the method of expressing the acidity in terms of
lactic acid is purely conventional, it nevertheless suffices for
purposes of comparison. The indicator employed in titrating
with sodic hydrate is important, since it has been shown that
phenol-phthalein gives values at least four or five times as high
as rosolic acid or litmus, both the latter giving practically the
same results. In the author's opinion it is preferable to employ
litmus paper.
Matters soluble in Cold Water and Ready-formed
Soluble Carbohydrates. As diastase is able to act upon
starch in the cold, it naturally follows that its presence will be
attended with the products of its action on the starch of the
endosperm of barley during germination.
During germination a certain quantity of the constituents of
; Chem. und Phys. des Maizes und des Meres, 40.
304 THE BREWEK'S ANALYST
the endosperm is rendered soluble and transformed into food for
the growing plant. It is unnecessary to enter into details as to
the manner in which the food is elaborated, but from the amount
of the bodies thus rendered soluble and contained in the finished
malt, much information is gained as to the character of the malt
and method of its manufacture.
The quantity of soluble carbohydrates formed is influenced by
the mode of treatment of the barley during vegetation on the
floor and during kilning. Moritz and Morris consider that an
excess of ready-formed sugar, or better expressed as ready-formed
soluble carbohydrates, in malt, point to errors in the malting
process. One or two things has happened : either the malt has
been forced, that is to say, its growth has been hurried at either
too high a temperature or with too much water, or the green
malt has been loaded to kiln too fresh, that is, containing too
much moisture.
In the former case an excess of soluble matters is produced ;
in the latter case the food which should have been normally
assimilated by the root remains in the grain.
In their opinion the ready-formed soluble carbohydrates should
not exceed 16 per cent., and malts containing a higher percentage
than this are stated to give bad results in brewing.
Abnormally low percentages (under 10 per cent.) point to
insufficient germination.
In this way Moritz and Morris propose to use the estimation
of ready-formed soluble carbohydrates as a test for the way in
which the malting process has been conducted. The utility of
the method has, however, on several occasions been contested,
and it is evident that an improved method of estimation is
required.
The amount of ready-formed soluble carbohydrates should not
in themselves be taken as an index of " forcing " or "non-forcing,"
since it is frequently found that malts showing an excess of these
bodies may yet give good results in brewing. A malt may in
fact show an excess of these bodies and yet be excellent in other
respects, so that it should not be condemned on this factor alone.
On the other hand, a " forced " malt always shows a high percent-
age of ready-formed soluble carbohydrates, and of soluble
coagulable albuminoids, and the percentage of acid will also be
high in proportion, so that the test when compared with other
results is most valuable.
Roughly, we may allow for English pale-ale malt up to 15 '5 or
16 per cent., about 16 to 16*5 for mild-ale malt, and up to 17
INTERPRETATION OF THE RESULTS OF ANALYSIS 305
per cent, for running, black-beer malts. For stock black beers,
however, the percentage should not exceed 16. With foreign
malts the percentage may be up to 14 '5 for Calif ornian, showing
an extract of 88 Ibs. per quarter, and from 11 to 14 for thinner
varieties.
It is not, then, so much the existence of these products as such
that constitute the danger, but the fact that their excessive
formation usually corresponds to the production of undue pro-
portions of soluble uncoagulable nitrogenous extract. It is
difficult to conceive how a difference of even less than 0'5 per
cent, in the proportion of uncoagulable nitrogenous extract should
influence the stability of brewery produce, but practical experience
proves that the continuous use of malts of this character speedily
conduces to yeast weakness, the organism apparently becoming
supersensitive to modifications in wort composition.
Colour. 'The determination of the colour value of malt wort
is one over which there has been great controversy. Many
analysts record the colour as found by examining the 10 per cent,
wort from the miniature mash made for determining the extract
value; others are content by recording the colour of a 10 per
cent, cold-water extract ; others, again, employ either of these
worts and calculate the result to percentage on the malt ; whilst
more generally the colour is established from the hot 10 per cent,
mash wort, and then by a rule-of -three sum it is worked out
what the colour would be for a gravity of 1055. 1
Since the colour depth does not vary directly as the density,
this latter method is obviously wrong. The method described in
Part VI. has been shown by Heron to be correct, and should
therefore be adopted. The colour of a malt is undoubtedly a good
criterion of the firing during kilning, and, taken in conjunction
with the diastatic capacity, is a safe criterion as to whether the
malt has received proper treatment during kilning.
A diastatic power for a pale-ale malt ought not to be below 35
or more than 44, a mild-ale malt from 23 to 30, and a high-
dried malt from 15 to 23. The tintorial values, in like manner,
for a pale-ale malt ought not to be below 4 or more than 6, a
mild-ale malt from 10 to 15, and a high-dried malt from 15
upwards.
When we find a pale-ale malt possessing a diastatic power of
40 and a tintometer value in the 1 inch cell of 4 units of colour,
we know that we are dealing with a malt of good quality. Such
a malt will show that the growth on the floor has been carefully
1 Brian? s Laboratory Text-book, p. 128.
20
306 THE BREWER'S ANALYST
attended to, that proper withering has taken place, that it has
been carefully and thoroughly dried on the kiln before the
temperature was raised to any appreciable degree, and that the
curing was carried out in a proper and efficient manner.
On the other hand, when we find a malt showing such results
as the following : a diastatic power of only 18 to 20 and total
units of colour 3 such a malt will be hard to the bite, possess
moisture above the normal, and be unsatisfactory in every
respect; and although these results do not necessarily imply
that the malt has been carelessly grown or improperly attended
to whilst on the floor, one thing they do show, and that is, that
the malt has been spoilt on the kiln.
In all probability the malt has been loaded to the kiln very
imperfectly withered, or not at all, and with a great deal too
much moisture in it. In such cases forcing, in the truest sense
of the word, takes place in the early stages of drying; and in
order to avoid this, and reduce the moisture as quickly as
possible, the temperature is speedily raised. By such means the
diastase becomes very much restricted, and there is danger if the
temperature be carried much higher than 160 F. (71 '1 C.), of a
large amount of colour being produced, hence insufficient curing
must necessarily follow.
With a properly grown, well-dried malt it is possible to raise
the curing heat to, and maintain it at, a very much higher tem-
perature than could otherwise be done, without producing any
appreciable increase in colour.
Diastatic Power. The method adopted is based upon the
researches of Kjeldahl, 1 and depends upon the amount of reducing
sugars produced when extracts of malt are allowed to act upon a
solution of soluble starch under denned conditions, the most
important of which are that the proportion of diastase employed
relative to the starch to be transformed, and the time of the
reaction, shall be sufficiently limited to prevent the formation of
reducing sugars in excess of a K of 25 as 30, or expressed in the
maltose equivalent as R of 40-50. Operating under these condi-
tions at an elevated temperature approximating to 140 F.
(60 C.) a temperature that he had proved as most favourable
to the action of the enzyme he established the law that the
relative diastatic power of two malts is proportional to the sugar
produced. Some ten years later C. J. Lintner 2 modified this
gravimetric process, allowing the action of diastase to take place
1 Compt. rend. trav. Carlsberg Lab., 1879.
2 Wochenschrift fur Brauerei, 1886, 733, 753,
INTERPRETATION OF THE RESULTS OF ANALYSIS 307
in the cold, and adopting a volumetric method for determining
the exact amount of reduction. It is the "Lintner" process that
is described in former pages and the one now generally employed ;
standards, as already stated, ranging from 15 to 23 being regarded
as normal for high-dried malts, 23 to 30 for mild-ale malt, and
from 35 to 44 for pale-ale material.
Whatever the diastatic power of the malt when loaded to kiln,
during drying the diastase is reduced about one-half ; but the
actual reduction depends upon the moisture content of the green
malt when loaded, and the temperatures employed, particularly
during the early stages of kilning. Obviously a high-dried malt
contains less diastase than a low-dried one, and the two classes of
malt require appropriate mashing temperatures low for those
low in diastase, and high for those containing much diastase.
Yet mashing temperatures must not be governed alone by diastatic
power, but by the tenderness of the malt, a well-made, tender malt
permitting the use of a higher mashing temperature than a
steely one.
The diastatic power of malt should not be below 15 or over
44. If below 15, it points to the malt being inefficiently
vegetated ; whilst if above 44, either the diastase has not been
properly reduced during kilning, or the malt has originally been
abnormally diastatic, which proves faulty manufacture. The
colour and diastatic power should have some connection ; for
instance, the presence in a high-dried malt of a proportion of
diastase normal to a pale-dried malt, shows the original diastase
to have been excessive.
Proteids Or Albuminoids. A malt contains a slightly less
amount of nitrogenous matter than the barley from which it is
made, since a portion of the nitrogenous substances passes into
the rootlets which are removed from the finished malt. During
malting, however, a large proportion of the insoluble nitrogenous
bodies present in the barley are rendered soluble.
The average percentage of the total nitrogenous bodies and of
the soluble modifications may be taken on English malt as
follows :
Total nitrogenous matter . . . 9 '80 per cent.
Soluble . 2-50
Insoluble 7'30
With malts sufficiently forced so as gradually to produce actual
trouble, the soluble nitrogenous bodies will run up to from 2-8 to
3 '2 per cent.
308 THE BREWER'S ANALYST
Foreign malts should not show more than 1'8 or 1*9 per cent,
for the normal percentage of ready-formed soluble carbohydrates
which they contain (11 to 14 per cent.).
Malt made from Danubian barleys, however, show up to 2 '4 per
cent., and are decidedly unsatisfactory brewing material.
Moisture. The presence of moisture in malt varies with the
conditions of kilning and the method and time of storing. A
malt just off the kiln, if properly cured, may contain as low as
0*5 per cent., but shortly afterwards the moisture will be found
as high as 1*5 or even 2 per cent.
Malts coming from a distance absorb moisture during transit,
and usually contain from 2 to 3 per cent, of moisture.
A malt containing from 3 to 4 per cent, of moisture may be
considered "slack," and such malt should be redried before use.
Beyond 4 per cent., provided the slackness is due to faulty
storage, the malt should be condemned as unfit for use, as it will
have suffered internal deteriorations which, though not readily
expressed in definite terms, cannot fail to show their bad influence
on the flavour and keeping properties of the beer.
Physical Examination. The chemical examination of malt
is admitted by all to be essential to the true evaluation, and the
foregoing details all more or less go to prove this fact. It is
undoubtedly true that the value of a malt may be well judged
by a physical examination, but it is equally true that appearances
are at times deceptive, and that although a malt may be good
so far as the eye, the nose, and the mouth can detect, it may
nevertheless prove bad by chemical analysis. In any case it is
impossible, by physical examination, to arrive at the degree of
acidity, diastatic power, extract, albuminoids or moisture, and
the importance of these factors are obviously known to the
practical man. Again, it is impossible, by physical examination,
to state whether the malt has been forced or correctly kiln-dried,
or whether it is suitable or unsuitable, from a diastatic point of
view, for the manufacture of any particular class of beer. On
the whole, malt, unlike barley, cannot be judged other than both
physically and chemically ; and although the former is essential,
the latter is equally important, not only where value is concerned
commercially, but as to whether or not the malt is capable of
answering the particular purpose for which it is intended.
From a physical point of view the "bite" of the malt is
important, and instead of a corn here and there being selected
and bitten in two, it is best to chew a mouthful, noting the
tenderness and flavour and also the colour* of the well-chewed
INTERPRETATION OF THE RESULTS OF ANALYSIS 309
material when removed from the mouth. By these means the
experienced man can form an excellent opinion as to the degree
of modification, the amount of firing the malt has received, and
the general character of the malt from the flavour it yields.
It is impossible to describe the characteristics in these respects
which go to define the quality of a malt, and it is only by long
practical experience that one can form a correct judgment. They
are factors, however, of every importance, and absolutely necessary,
in conjunction with a chemical analysis, in the true evaluation of
malt.
Again, the degree of growth by examination of the acrospire of
several corns, the selection of steely or semi-vitreous corns and
the separation of " misses " or dead corns which may be looked
upon more or less as raw grain, are also necessary factors in
judging the quality of malt; whilst lastly, although neither
physically nor chemically is there any test competent to distinguish
between "new" and carefully stored matured malt or "new"
and redried old grain, the practical man nevertheless fully ex-
periences the influence of age upon brewing results : perhaps,
however, the loss of interest on locked-up capital reduces the
chance of the otherwise certain appearance of redried old grain.
BIOLOGICAL EXAMINATION OF BARLEY AND MALT.
The biological examination of barley and malt, if justly judged,
is of some considerable importance. It has been shown by the
experiments of Becker that barley steeped in the ordinary manner
carries with it to the floors a tremendous number of micro-
organisms; in fact their numbers, capable of development, vary
from 5,500 to as many as 12,350,000 in each gram of the barley,
and as every one of these organisms or their spores may, under
favourable conditions, multiply in 24 hours to 30,000 or even
300,000, it is self-evident that it is important to wash barley
prior to steeping.
Green malt naturally carries an enormous number of micro-
organisms, many of which are destroyed by the kilning tempera-
tures; but before the kilning takes place, fermentations of an
undesirable nature often set in and result in the communication
of objectionable odours and flavours to the malt, causing chemical
changes of an undesirable nature to take place and cloudiness in
finished beer.
The value of the biological test with malts is important, and
centres in the fact that as the acidity they contain is mainly due
310 THE BREWER'S ANALYST
to soluble phosphates, the worts they yield nourish bacteria, so
that the higher the acidity the larger the quantity of phosphates
and the greater the nourishment and the quicker the time in
which the wort turns cloudy and putrifies.
In the author's opinion, a wort which remains clear on the
forcing tray for 36 hours is particularly sound, whilst one which
turns cloudy in a lesser time is unstable.
COLOUR MALTS.
Amber. Crystal. Brown and Black.
Amber malt, like crystal and brown, is employed by brewers
chiefly to impart flavour to beers, black malt being used mainly
for the purpose of imparting colour.
In the manufacture of amber malt the green malt is taken
from the floor at the withering stage, and is loaded on the kiln
at a depth of about 4 inches. The fuel used at the early stages
of drying is the same as in ordinary malting ; but when the malt
is hand-dry, the heat is augmented and very dry beech-wood is
thrown upon the fire, the products of combustion imparting the
desired flavour.
Very high-dried amber malts give a certain viscosity to beers
produced by their aid. Thausing states this to be due to the
existence of parapeptones in the malt, which give both colour and
viscosity.
Crystal, broivn, and black malts are manufactured by taking
malt at the withering stage, earlier than when manufacturing
amber, and roasting in a perforated cylinder enclosed in a cast-
iron casing and which can be freely turned.
A low coke fire is employed, and during heating the malt is
cautiously and slowly turned.
As the steam passes off, the fire is made up and the heat
increased. In 30 minutes a fine rich aroma is evolved from
the malt. Having imparted the desired colour and flavour, the
malt is then removed from the cylinder and placed on a floor to
mellow and cool.
If brown malt is desired, the heating is continued, and in 5 or
10 minutes a good brown or chocolate colour is imparted ; whilst
if black malt is wanted, the heating is further continued, and
in 40 minutes or so the operation for this class of malt is
complete.
Brown and black malts are sometimes finished off with a glaze.
INTEKPRETATION OF THE BESULTS OF ANALYSIS 311
This is performed by sprinkling the grain with a sugar solution
a few minutes before finishing off: the glaze so imparted darkens
the colour of the husk.
In place of sugar solution^- glycerine, either alone or with water
or steam, is sometimes employed for the same purpose, it being
claimed for this mode of treatment that the malt, unlike other
varieties, is free from acrid or bitter flavour, and that it possesses
a higher colouring power.
Weight. The weight per bushel of black malt varies a good
deal according to the quality ; the average medium-priced material
weighs about 31 to 32 Ibs. per bushel, but very high qualities are
frequently as much as 36 and even 37 Ibs. per bushel. But these
must not be confounded with roasted barleys, which also weigh
high.
Brown and crystal malts weigh from 31 to 33 Ibs., and amber
from 38 to 40 Ibs. per bushel.
Extract. The Ibs. per quarter extract obtainable from black
malts varies from 50 for low quality up to 70 for high-class
material. Brown and crystal malts, under usual conditions of
grinding, give from 55 to 60 Ibs. in each case. But the fineness
of the grinding has a marked effect on the extract with respect to
crystal malt especially, and if it be ground as fine as possible, the
extract will go as high as 75 Ibs. or more. There are somewhat
different opinions as to what constitutes an amber malt, some
brewers expecting much more severe curing than others ; and the
extent of the curing affects the extract. As a general average
the extract of amber is about 84 to 85 Ibs. per standard
quarter.
Moisture. Colour malts are highly hygroscopic or deliques-
cent, and upon arrival at th'e brewery will usually be found to
contain at least 3 per cent, of moisture, and upon storage for a
few weeks the moisture percentage will run up to 5 or even more.
It is inadvisable, from this fact alone, to keep any large stock ;
in fact the majority of brewers generally purchase only in small
quantities as and when required.
ColOUP. There is no standard method for ascertaining the
colour value or tintorial power of these so-called colour malts,
but on strictly commercial lines it is perhaps advisable to express
colour results in degrees of tint of a solution of 1 Ib. gravity in a
1 inch cell examined by Lovibond's tintometer, and compare this
with the price of 1 Ib. of extract. On the other hand, it is of
importance to the brewer to know what colour these malts in
definite proportion will add to his worts, and in such instances it
312 THE BREWER'S ANALYST
is best to approximately average brewery conditions in obtaining
a solution. Hence it is best to mash such proportions of the
colour malts as are used in practice with pale material of
known tint, and note the increase in colour due to the colour
malts. For purposes of comparison, however, a 0*01 per cent,
solution, examined by the tintometer as described in Part VI.,
is valuable.
Physical Examination. The better the quality of the
green malt employed for the manufacture of colour malts, the
better the quality of the resulting products.
A sample of roasted malt is uniform in colour, the interior of
each corn of a chocolate hue, not an intense black, and each corn
clear and clean. If the interior is an intense black with the corns
burst, and especially if matted together, it is of a most inferior
kind, and neither good flavour nor permanent colour can be
obtained from it.
RAW GRAIN.
Maize GritS. The oil should be under 1 per cent. ; nitro-
genous bodies not more than 9 per cent. ; starch not less than
74 per cent. ; moisture not more than 14 per cent. ; and the
extract derivable should be from 95 to 100 Ibs. per quarter of
336 Ibs.
Rice. As rice contains more starch than maize, and as the
starch gelatinises more readily than maize starch, the extract
derivable is obviously greater. The extract yield is from 100 to
105 Ibs. per 336 Ibs. The oil should be under *8 per cent. ; nitro-
genous bodies not more than 9 per cent. ; starch not less than 79
per cent. ; and moisture not more than 14 per cent.
Granulated or flaked Maize and Rice.
Maize. Rice.
Starch, not less than . . . . 79'0 81'0
Oil, not more than . . . .1*5 0'4
Nitrogenous bodies, not more than . 9 '5 8*5
Moisture, not more than . . .8*0 8'0
Particular care should be taken to observe that the starch of
prepared flaked or granulated maize or rice is not steely, as, if so,
it not only points to faulty manufacture, but the starch is
exceedingly refractory in conversion and the extract obtainable
consequently less ; for the same reason the extract should not be
calculated from the percentage of starch found.
INTERPRETATION OF THE RESULTS OF ANALYSIS 313
HOPS.
A good hop from both the grower's and the brewer's point of
view, according to Percival,V should have, as far as possible, the
following characteristics :
(a) The yield should be large, and the hops should be capable
of hanging on the plant without damage for some time, so as to
allow a considerable area to be picked and managed with a
moderate number of hands.
The time which a hop will remain in good condition without
"going off" depends upon the manuring, season, and locality to
some extent, but there are constitutional differences among hops
in respect of this quality. Fuggle's hops, for example, usually
hang well, while the thinner-petalled varieties are easily dis-
coloured and fall in pieces when left a few days in the picking
season.
(b) The plants should be hardy and highly resistant to the
attacks of fungi and aphides.
Unfortunately, delicacy and weakness are almost invariably
met with among hops of the best quality.
(c) The brewer aims at high lupulin content, for the chief use
of the hops to him depends upon the amount of resins present in
them. Moreover, for the process of dry-hopping, a pleasant aroma
is essential.
So far as the keeping quality of the beer is concerned, and also
to a large extent the peculiar bitterness imparted to the liquor by
the hops, a sample of good resin content, with only a passable or
even poor aroma, is as useful as one of fine aroma, or the hops
of the Weald or less-favoured districts would not be grown.
However, to impart the most delicate and attractive flavour to
beer, only hops of the best quality can be employed. The size of
the resin glands, their weight, and the number on each " petal,"
are generally greatest among hops of poor aroma ; but their
weight, compared with the rest of the hop, is often higher in the
best quality hops than in those of poor aroma and flavour.
In a good brewer's hop the petals should be well covered at the
base with lupulin, and the "strig," "petals," and "seeds" should
weigh as little as possible.
Hops with the most delicate aroma possess thin, smooth, pale-
golden "petals," the bracteoles being well rounded at the tip, and
the stipular bracts similar in colour and texture, and broadly oval
in shape.
1 Jnl. Royal Agric. Soc. of England, vol. Ixii., 1901.
314 THE BREWER'S ANALYST
Those of poor aroma have "petals" which are generally rough,
thick, and puckered. The bracteoles are more pointed, the
stipular bracts being narrow, and often a darker graen tint than
the bracteoles, so that the colour of the hop is not uniform all
over, and cannot be made so, even by the strongest application
of sulphur on the kiln.
The worst variety has the small stipular bracts, at the base of
the strobile, twisted.
Some varieties of hops have exceptionally pale, straw-coloured
" petals " which are very thin ; such are always deficient in resin
glands, but the aroma is generally good.
A sample of hops, if perfectly dried, is extremely elastic ; when
released after being pressed, it immediately resumes its former
bulk.
Hops which are used for dry-hopping should not disintegrate
too readily, or, as it is termed, be " marshy, 5 ' since the detached
fragments float in the beer, and are drawn off from the cask along
with it.
Marshiness is either caused by overripeness or some defect in
drying.
Lastly, hops should be free from mould, and in no instance
should any be accepted which possess the slightest objectionable
odour.
The respective proportions of the different constituent parts of
the hop cone mechanically separated, are given by Haberland as
follows :
Lupulin . . . . 7*92 to 15-70 per cent.
Leaves . . . .69-79 78'36
Stems .... 8-50 17'54
Eipe seeds . . . 0*02 7'80
Hops are in their prime condition only after from 2 to 3 months'
storage. The oils previous to this sometimes tend to cause cloudi-
ness in finished beer, and the practical brewer, as a safeguard,
therefore uses considerably greater proportions of "yearlings," as
hops twelve months old are called, than of new hops. When two
years old they are designated " old hops," and at the end of three
years, by which time they are of little or no value, they are termed
"old olds."
The case is different, however, with cold-stored hops. Cold
storage reduces, but does not entirely arrest, change. For
practical purposes, however, cold-stored hops, if of good quality,
undergo very little deterioration in the course of one or two years,
INTERPRETATION OF THE RESULTS OF ANALYSIS
315
and it sounds to sense that beyond this it would, for commercial
reasons, be unwise to store them.
Hard and Soft Resins. The following shows the average
percentages of hard and soft 'resins in new hops :
New Hops.
Non-preservative
Hard Resins.
Preservative
Soft Resins.
Total.
Worcester .
5-03
770
1273
Sussex . . '
5-40
9'06
14-46
East Kent . ,
3'80
1074
14-54
Goldings .
4-12
11-42
15-54
Californians
8-20
12-46
20-66
Bavarians . -". j
810
11-42
19-52
Deterioration of Hops as judged by the Oxidation of
the Tannin.
New Hops. 4 Years old. 8 Years old.
Tannin per cent. Tannin per cent. Tannin per cent.
Sussex
Best Kent
6'2
5-4
4-0
2-7
4-6
3-8
3-3
4-0
2-2
2-6
0-8
1-2
1-2
0-9
07
none
1-3
1-2
0-6
none
none
0-2
none
none
The greater part of the oxidation appears to take place during
the first year of keeping, as is seen from the following results from
examination of first-class copper Mid-Kent hops :
January 7th .
March 3rd
October 26th ,
December 4th
2' 61 per cent, tannin.
2-03
1-26
1-20
Moisture. The normal moisture content of hops is 10 per
cent., since hops containing a greater percentage soon come down
to this on storage.
Sulphur. The hop bine during cultivation is often treated with
sulphur or solutions containing the same, and during drying in the
oast-house the coke fires are sprinkled with sulphur or sulphur is
burnt above the fire, in which cases sulphurous acid fumes pass to
the hops.
316 THE BREWER'S ANALYST
The practice of sulphuring the bines was years ago proposed by
Liebig, and there is no doubt that it acts as a valuable germicide.
The practice of sulphuring in the oast-house during drying is
also good, in so far as the sulphurous fumes here also act as a
germicide.
It has not yet been definitely proved, but nevertheless practical
experience has shown, that a sulphured hop keeps longer than an
unsulphured one ; and on the whole, provided sulphur is not
employed to excess or to cover defects or disguise the real
character of the hops, the practice can hardly be condemned.
Brewers, however, attribute yeast troubles and beer stench to
the use of hops containing sulphur, and under these circumstances
it becomes necessary to test hops for the same, so that when found
the hops may and should be rejected.
Biological Examination. Behrens estimated the number
of organisms and mould fungi in both sulphured and unsulphured
hops as follows :
Description of Hops.
1 Gram of Hops contained
Total Organisms.
Mould Fungi.
Unsulphured .....
Sulphured
13,637,600
8,056,300
422,800
169,200
From this the effect of sulphuring in diminishing the number
of organisms and mould fungi is unquestionable, and it follows
that sulphur rightly applied is beneficial.
SUGARS.
RAW SUGARS.
The sugars of commerce may be roughly divided into two
classes, Raw and Refined, each class containing many varieties and
qualities running imperceptibly one into the other. There is a
broad line of distinction, however, to be drawn between the two,
for the term "raw sugar" is generally applied to sugar manu-
factured in a more or less crude manner on the plantation where
it is produced, whereas the term " refined sugar " appertains more
directly to those finer qualities of sugar which are manufactured
INTERPRETATION OF THE RESULTS OF ANALYSIS 317
from the raw by subjection to a repeated process of purification,
this being generally accomplished at central factories far distant
from the country where the sugar is grown, on account of the
cost of coal, etc.
In the manufacture of refined sugar it is a matter of some
considerable importance to the refiner not only to know how much
cane-sugar the sample of raw product which he is going to treat
contains, but also the actual amount of cane-sugar which he can
obtain therefrom in the process of refining, and which is known
as the available amount of crystallisable sugar ; for it is now a
well-established fact that the presence of salts of mineral and
organic acids, as well as invert-sugar and organic bodies other
than sugar, exercise a marked influence upon the crystallisation
of sugar.
A study of these bodies, and the effects produced by them upon
crystallisation, has given rise to a method of valuing raw sugars
which has been adopted in France and Germany as well as in this
country, and is known as the t( rendement," or the net amount of
crystallisable sugar obtainable from a given sample of raw sugar.
This assumes that for every 1 per cent, of ash contained in the
raw sugar, 5 per cent, of cane-sugar is prevented from crystallising ;
and that for every 1 per cent, of invert-sugar present, an equal
proportion of cane-sugar is retained in the molasses. Hence the
rule, from the amount of cane-sugar found by polarisation, deduct
five times the weight of ash plus the weight of invert-sugar which
may be present : the remainder is taken as the refining value or
" rendement " of the sample. Thus, a sugar showing an analysis
Cane-sugar . . . . .90 per cent.
Invert-sugar . . . . 3
Ash . . . . . 1 ,,
would, according to the above method, give 90 - (1 x 5 + 3) = 82
per cent, of available crystallisable sugar.
To the invert-sugar manufacturer it does not matter, however,
whether there be much invert-sugar present in the raw material
or not ; he bases, therefore, the value of the sample on the total
amount of sugar (cane and invert) which can be obtained. So
that a sample which might be altogether rejected by the refiner
on account of the high percentage of invert present, would be
acceptable to the saccharum manufacturer, provided that the
other bodies present, organic and mineral, were not exceptionally
high.
Analyses of some of the principal varieties of raw cane-sugar
318
THE BREWER'S ANALYST
used in the manufacture of invert-sugar are shown in the following
table by Heron :
Cane
Cane
Jaggery.
Jaggery
partially
Penang.
Egyptian.
refined.
Cane-sugar
75'04
91-07
76-00
80-38
Invert-sugar
11-06
3-04
11-79
4-30
Other organic matter
3-25
0-81
2-60
0-81
Ash .
5-46
0'62
2-85
7-32
Water
5-09
4-46
6-76
7-19
Heron says : "As will be noticed, on studying the analysis, all
raw sugars contain what, for want of a better name, are termed
organic matters other than sugar, or non-sugar ; these may be
divided into three distinct classes, namely, organic acids, nitro-
genous bases ; and non-nitrogenous substances. From such sub-
stances upwards of sixty definite chemical compounds have been
already separated, and their properties determined ; most of
these are very undesirable bodies to have in malt wort or beer,
hence most of the raw sugars should be rejected as unsuitable for
the production of even the commonest kinds of ales and stouts."
This is perfectly true, but provided the brewer purchases only
the finest of raw sugar, such as the better class, partially refined
jaggery or Egyptian, he is perfectly safe in employing it both
in common ales and stout, and in inverting it for pale- ale
production.
When purchasing raw sugars for running mild ales or stout,
or for inversion purposes, only those should be selected which will
give a solution possessing a rich and luscious flavour. For
priming purposes only the very highest class sugars should be
employed. The candy sugar frequently used for this purpose, as
well as the well-known coffee crystals, are remarkably pure and
contain over 99 per cent, of actual cane-sugar.
Beet-sugars should in no instance be employed, as they always
communicate objectionable flavours.
SUGAR INVERSION.
The process of inverting cane-sugar consists in transforming
such sugar into dextrose and levulose, two forms of sugar which,
when combined, constitute the well-known invert-sugar or
saccharum.
INTERPRETATION OF THE RESULTS OF ANALYSIS 319
The transformation may be brought about by acids, such as
sulphuric or hydrochloric, or by certain enzymes derived from
animal and vegetable substances as, for instance, the animal
enzymes contained in their intestinal juice, or the vegetable
enzymes such as diastase contained in malt, and the invertin or
invertase contained in yeast. Whether the transformation is
brought about by an enzyme or an acid, the reaction is the
same ; that is to say, it consists in the assimilation of water by the
sugar molecule, followed by its separation into two different
kinds of sugar dextrose and levulose which, although possessing
the same molecular composition or formula, possess very different
properties. The formula for cane-sugar, C 12 H 22 O n may be written
thus :
PRO) which, when undergoing inversion, splits into
p 6 u- 10 () fj two molecules, one of which at the same time
takes up a molecule of water (H 2 0), thus :
^6^10^5 I _i_ R p, PR O-4-PTT O
p TT n I + 2 6 12 6 6 12 6-
C 6 M 10 U 5 I
Following up this nomenclature, we see that the sugar has
already the molecule dextrose contained within itself as it were,
whilst the C 6 H 10 5 molecule becomes hydrated to levulose. Both
these sugars are fermentable; but during the stage of fermenting
worts, if cane-sugar has been employed, the yeast has first of all
to transform it into invert-sugar before it can split it up into
alcohol, carbonic acid, etc. It is therefore concluded that if cane-
sugar is employed, the yeast during the fermentation of the wort
will become seriously weakened by reason of the double function
it will be called upon to perform. In 1892, however, this was
disputed by J. O'Sullivan, who says ; " The power which yeast
possesses of producing alcoholic fermentation is not altered in any
way by the yeast having first hydrolysed cane-sugar."
The methods of inverting sugar on the brewery premises as
carried out by the brewer are by the aid of either acid or yeast
(invertase) and are practically as follows :
ACID PROCESS OF INVERSION.
A wooden vessel containing wooden rakes is necessary for the
purpose, as the acid would act upon the metal if a metal vessel or
one containing metal fittings were employed. Water is run into
the vessel, the quantity being 0*6 of a barrel for every cwt. of
sugar to be inverted. The sugar is then added, rakes started, and
320 THE BREWER'S ANALYST
steam injected until a thorough solution is obtained ; but the
solution is not boiled, as caramelised products might be formed
and extract lost. At this stage pure sulphuric acid. sp. gr. l'S4,
is cautiously introduced, the quantity being 0'8 of a Ib. per
cwt. of sugar. 1 The solution is now brought to a temperature of
180 F. (82 C.), maintained at this temperature for 45 minutes or
more until such time as a sample, upon being neutralised and
tested, shows the inversion to be complete ; generally speaking,
45 minutes is sufficient time.
The solution is then neutralised by the addition of milk of lime
(calcic carbonate CaC0 3 , thoroughly mixed with water), the
quantity being 1*7 Ib. of lime for every Ib. of acid used. The
solution is now thoroughly roused (rakes going) for about 5
minutes, and is then allowed to stand for about 4 hours, by
which time the sulphate of lime, formed by the combination of
the acid and lime, will have subsided. The solution is then
filtered through a simple bed of granulated animal charcoal and
in a perfectly brilliant condition run to the copper, underback, or
other vessel.
Great care must be taken in weighing or measuring the acid
and in weighing the whiting before adding them to the sugar
solution, and it is essential that they should be added very slowly
and a little at a time. According to this method, at a temperature
of 180 F. (82 C.) from 95 to 98J per cent, of the sugar should
be inverted in 45 minutes. These figures are, however, only
theoretical, and such percentage is never obtained in practice.
Much of course depends upon the quality of the raw cane-sugar
employed. During inversion the acid produces substances termed
" inert carbohydrates " to the extent of from 10 to 14 per cent,
and often more. These bodies yield weight, and therefore do
not lessen the gross extract unless previously filtered out;
and bein<; totally unfermen table, they may be looked upon as
so much loss.
The extract obtained from brewery-manufactured invert varies
with the quality of the raw cane-sugar employed and the ability
displayed in manipulation : 72 Ibs. per 2 cwt. may be taken as a
reasonable average, whilst 76 Ibs. may be readily obtained from a
really good and well-refined sugar.
1 To find the equivalent in fluid ounces :
16 oz. water=l Ib. 16 *' 8 = 6-95,
1 *84
therefore approximately 7 fluid ounces of acid may be used per cwt. of sugar,
and the trouble of weighing the acid obviated.
INTERPRETATION OF THE RESULTS OF ANALYSIS 321
INVBRTASE PROCESS OF INVERSION.
The process of inverting sugar by the aid of yeast (invertase) is
indeed simple. Sugar and water, in the proportion of 1 part of
the former to 4 parts of the latter, are added to the inversion
vessel, rakes are started, and the temperature raised by steam
inlets (or preferably steam coil) to from 131 to 140 F. (55 to
60 C.). Such temperature is sufficient to in time dissolve the
sugar, and is most favourable to the complete inversion. When the
sugar is dissolved, the solution is filtered through a bed of animal
charcoal and passed back to the inversion vessel. Fresh, vigorous
yeast is then added, 1 the amount being about 1 per cent, on the
weight of the sugar, and the solution is kept in agitation, by
means of the rakes, for 4 hours. The time specified is sufficient
to invert the sugar, but the quantity inverted depends greatly on
the total amount of yeast allowed to play upon the solution, and
it is therefore impossible to confirm any two sets of experiments
conducted with varying measures of surface area, or, in other
words, with unlike quantities of yeast. For instance, every
brewer is aware that yeast cells, when undisturbed in a liquid,
follow the general law of displacing a volume of fluid equal to
their own weight ; it therefore follows that if two solutions of 5
and 20 per cent, of sugar respectively, were infected with the same
quantity of yeast and not kept constantly agitated, the yeast would
subside far more rapidly in the 5 per cent, than in the 20 per cent,
solution. Taking it, however, that we constantly agitate the fluid,
and that the proportions of water, sugar, and yeast as well as the
temperature are as stated, complete inversion results in 4 hours.
Such a simple method of manipulation undoubtedly recommends
itself, and no prejudice can exist as it does against the use of acid.
There are no inert bodies formed, and the whole of the extract,
which is that of the original sugar plus the increase due to
hydration, consists entirely of invert-sugar. Such extract should
be readily obtained in practice to the extent of 88 Ibs. per 2 cwt.
of sugar.
The speed of inversion increases rapidly with the temperature
until 131-140 F. (55-60 C.) is reached. At 140 F. (60 C.)
the invertase is slowly destroyed, and at 167 F. (75 C.) it is
immediately destroyed. At the lower temperature, the speed of
action increases with rise of temperature in accordance with
Harcourt's law, the rate being about double for 10 rise, but
above 30 the increase is not nearly so rapid.
1 In practice yeast is employed, and not a prepared extract.
21
322 THE BREWER'S ANALYST
Elevated temperatures have no permanent effect on the activity
of invertase, so long as they are not sufficiently high to destroy it ;
and the favourable temperatures to the inversion, viz. 131-140 F.
(55-60 C.), are beyond the point of the fermentative and vital
energy of the yeast organism.
Minute quantities of sulphuric acid (0'20 per cent.) are
exceedingly favourable to the action, but a slight increase of
acidity beyond the most favourable point is very detrimental.
The caustic alkalies, even in small proportions, are also instantly
and irretrievably destructive of invertase. As, therefore, all raw
sugars vary considerably in these respects, that is to say, some
being distinctly acid arid others alkaline, the question of
manipulating the sugar solution so as to render it slightly acid
before adding the yeast, has to be reckoned with, or little or no
inversion will take place. This, however, is not a grave drawback
provided the brewer prepares himself to meet the requirements
with every sample of sugar he manipulates ; it being merely
necessary to make, for instance, a 10 per cent, solution of the
sugar and test it by the acid or alkaline burette.
INVERT-SUGAR.
There are naturally various qualities of invert-sugar on the
market, varying with the character of raw sugar originally dealt
with, the conditions of inversion, and whether or not final solidifi-
cation is effected artificially.
A sugar only partly inverted, that is to say, containing an
excessive amount of unconverted cane, will not solidify after
being removed from the vacuum pans, no matter to what ordinary
degree of concentration the sugar has been subjected during the
boil.
A large percentage of cane-sugar may not be objectionable,
but it points to the fact that the sugar has been incompletely
inverted.
The presence of much mineral matter or an excess of un-
fermentable bodies point to incomplete filtration through animal
charcoal, and to the fact that a low-class sugar has been, in the
first place, employed.
The better the class of sugar employed for inversion, the more
readily will the resulting invert solidify when removed from
vacuo, hence the solidity is some criterion of the quality of the
sugar. It should be remembered, however, that the cheaper
sugar glucose is sometimes mixed with invert in order to
INTERPRETATION OF THE RESULTS OF ANALYSIS 323
improve the colour, cheapen the cost of production, and effect
solidification. All samples of sugar sold as invert should there-
fore be tested by the polarimeter for added glucose, and where
this is found an estimation of the quantity should be made, and
the true value of the sample ascertained.
The colour of the solution should not be excessive, as high colour
points to poor purification by filtration through charcoal. The
acidity should also be low, as otherwise it points to incomplete
neutralisation. The qualities of invert naturally vary with the
price, but the well-known No. 1 and No. 2 qualities of different
manufacturers should be of a good degree of purity and strength.
The following figures show reasonable requirements :
No. 1. No. 2.
Invert-sugar, not less than . . 74'0 72*0 per cent.
Cane-sugar, not more than . -. 1*5 2*0
Mineral matter, not more than . 1-75 2'25
Unfermentable bodies, not more than 3'0 4*5
Optical activity, not less than . . - 10[a] D -7[] D
SACCHARINES PREPARED FROM STARCH.
GLUCOSE.
Kirchoff, in the year 1811, was the first to prepare glucose or
dextrose by the action of sulphuric acid on starch, and although
very many modifications have since been introduced, it is still
made substantially in this way.
Hydrochloric acid has been found the best for converting
starchy materials, but in practice, like with cane-sugar inversion,
pure sulphuric acid is used. Other acids are, however, sometimes
employed, such as oxalic and phosphoric, and the conversion is
often carried on under a pressure varying from two to ten
atmospheres. Pressure accelerates the process, but there is the
objection that such pressure causes caramelisation, and as a result
dark-coloured products are obtained. This is of slight considera-
tion where animal charcoal filtration is afterwards resorted to,
because nearly all such inert bodies are thus removed, and
decolorisation to a very considerable extent effected ; in fact it
is only when the solution contains a very large percentage of
caramel that the decolorisation is not effectual.
Glucose readily ferments under the action of yeast, requiring
no conversion, as is the case with cane-sugar.
It is a comparatively easy matter to accurately value a sample
324 THE BREWER'S ANALYST
of commercial glucose. The colour of the solution should not be
excessive, as too much colour is a certain sign of either bad
material or bad manufacture, or both combined. The solution
should be fairly bright, or otherwise it points to the presence of
an excess of proteid bodies. The ash should not be much over
1 per cent., as a higher percentage shows faulty nitration. The
acidity should be low, or it points to incomplete neutralisation.
The extract should not be much under 77 Ibs. per 2 cwt. per
barrel, that is, it should not contain much more than 10 per cent,
of water and no samples should give less than 73 Ibs. per 2 cwt.
per barrel, that is, should not contain more than 15 per cent,
of water.
Samples which contain dextrin always contain more water than
when this substance is not present.
The fermentable matter should not be less than 70 per cent.,
or, if calculated on the dry extract, not less than 80 per cent, of
the latter. There is no reason why this should not partly consist
of maltose.
It is generally considered that proteid bodies should be absent,
or present in small quantities only, for, if even small percentages
be present, it is a sure indication that the sugar has been prepared
from imperfectly purified material. The percentage of proteid
bodies in English maize glucose is about 1 J to 2, and in American
glucoses considerably lower, ranging from 0'14 to 0*19 per cent.
Continental glucoses, however, are sometimes prepared from
potatoes, and in such instances are very objectionable, as they
invariably contain traces of the unpleasant alkaloid present in
that plant.
DEXTRIN-MALTOSE, MALTODEXTRINS OR AMYLOINS.
These substances are prepared from starchy materials on some-
what the same lines as in the manufacture of glucose, the
difference being that the acid conversion is stopped at a point
before the starch has been hydrolysed to glucose ; that is to say,
for example, when the product of the reaction has a specific
rotatory power of about [a]j!93, and a cupric oxide reducing
power of about 21.
By stopping the reaction sooner, or allowing it to proceed
further, or by altering the proportion of acid to water, or the
temperature and pressure at which the reaction takes place, the
solutions are made to contain various proportions of dextrin and
maltose; hence the proportions of dextrin and maltose vary
INTERPRETATION OF THE RESULTS OF ANALYSIS 325
greatly in these materials. Such products contain very little
dextrose or glucose, sometimes none at all, but may occasionally
be found to contain unconverted starch, the latter in cases of
imperfect manufacture.
The sugar is naturally fluid, and sent out in a clear and nearly
colourless condition. Owing to such solutions containing dextrin
and maltose to some extent in a combined state as " malto-
dextrins" or "amyloins," they are only partially and slowly
fermentable. They were much in use ten or fifteen years ago,
particularly as priming syrups, on account of the slow and
continuous "conditioning" which they are capable of imparting
without rendering beers too sweet.
CARAMEL.
The average colouring power of good caramel is 18 on '01 per
cent, solution examined by the 52 series of yellow glasses in
Lovibond's tintometer.
The average density of fluid caramel is 1*377 ; the average
cupric oxide reducing power 33'87 per cent, (as glucose) on the
fluid product ; and the mineral matter or ash should not exceed
0'80 per cent.
The specific rotatory power and degrees of fermentability
should be low.
Most caramels are partially fermentable, but considerable
fermentability points to imperfect preparation, since the original
sugar should have been converted into unfermentable bodies.
By over-conversion, considerable inert bodies and insoluble
carbon are formed, and these are generally greater in solid
caramels \ they reduce the extract value and tintorial power, but
although the carbon has no effect and does not prove the caramel
to be a bad one, yet the presence of an excessive quantity of inert
bodies is objectionable in view of the fact that little is known of
their composition or behaviour when added to wort or beer.
All good caramels when in solution possess a rich flavour which
readily distinguishes them from inferior varieties.
Some caramels have liquorice mixed with them, and others
various proportions of the extract derived from oats; they are
used solely in the manufacture of stout, for which purpose they
possess advantages where the particular flavours imparted by
them are desired.
PART IX.
MICROSCOPICAL AND BIOLOGICAL.
MICROSCOPICAL.
The MiCPOSCOpe. Without doubt a really good microscope
is an invaluable instrument to the brewer, and in his hands, pro-
vided he thoroughly understands its use, and further, how to
diagnose the appearance of the substance he is viewing, it is to
him what the stethoscope is to the physician or the compass to
the mariner.
There are variously constructed instruments on the market
ranging in price according to the actual requirements of the
purchaser, but for all necessary brewing and malting purposes a
really good instrument may be purchased for about seven or
eight pounds.
It is unnecessary here to go into minute details regarding the
construction of the various microscopes, and indeed to do so would
occupy too great a space ; and as particulars can readily be
obtained from numerous text-books dealing solely with this
subject, we need only briefly deal with the important points.
The compound microscope (Plate VIII.), from a mechanical point
of view, consists of a tube A, known as the body tube, upon the
lower end of which an internal thread is chased, into which the
various objectives B are screwed in turn ; or the " nose-piece," as
the end of the tube is called, may be constructed with a slide
attachment carrying two or three objectives, so that by the mere
turning of the attachment the desired objective may be brought
into position without the delay of having to take off one objective
in order to screw in another. Obviously the sliding attachment
is more convenient and saves much time.
Into the body tube A there slides another tube C, termed
the draw tube. This is open at its upper end, and into this
326
Hil:>'iis ]->r<- trcSs Anal list. \
D
PPLATE VIII.
B
H
FIG. 80. (i Full Size.)
[To face p. 326.
OF THE
I UNIVERSITY
OF
MICROSCOPICAL AND BIOLOGICAL 327
opening the various eye-pieces D are inserted. By means of
the draw tube C the length of the instrument can be varied,
thus enabling the microscopist to alter the distance between the
eye-piece and the objective. ^
The body tube A is moved up and down by rotating the large
milled-head E, and by this movement the " coarse adjustment "
of the distance between the objective and object is effected. The
pillar F has a triangular base, its movement being effected by
an exceedingly fine screw actuated by the milled-head G ; this
arrangement being known as the "fine adjustment." The tri-
angular pillar is fixed to the stage H, the latter consisting of a
brass plate perforated with an aperture immediately under the
objective.
The stage H is attached by a movable joint I to the pillar
J, which in its turn is fixed to the base of the instrument, the
latter being of considerable
weight in order to render the
instrument stable. Under
the stage the tail-piece K
is fixed, which on its lower
extremity carries the half
circle in which the mirror
L swings. The semicircular " --~-r--
piece is attached to the tail-
piece by a screw in such a way that it can be revolved on the
axis of the screw ; and this motion, combined with the swinging
one, enables the mirror to be placed at any required angle. In
using the microscope the mirror is placed at an angle so as to
illuminate the field of view which is obtained by transmitted
light, and obviously there is always a wide variation of the
incident beam of light both as regards its angular aperture and
its direction.
To meet this the well-known Abbe illuminating apparatus or
condenser M (fig. 81) was introduced in 1872, and is acknowledged
as an indispensable accessory, at least in advanced microscopic
work.
A further accessory which may be separately employed or
combined with the Abbe condenser is the iris diaphragm N
(fig. 82, A and B), which facilitates a very gradual variation of
the aperture. The smallest opening of the iris has a diameter
of about 1 mm., the largest one of 32 mm., so that it may re-
main in its place even when the condenser is used at full
aperture.
328 THE BREWER'S ANALYST
The most important portions of the microscope are the
quality of the lenses in eye-pieces and objectives, for on their
perfection depends the clearness and distinctness of the image
viewed.
The most common form of eye-piece consists of two plano-
convex lenses having their convex sides directed towards the
objective, with a diaphragm between the lenses. It is the
simplest and least expensive form of eye-piece, and is suitable
for all ordinary purposes ; in fact it is the best to use with
ordinary objectives, for as these are over-corrected and the eye-
pieces under-corrected, the two balance one another and give a
correct image.
Other "dry" objectives generally consist of three small
achromatic lenses. Each achromatic lense consists of two lenses
FIG. 82.
of different kinds of glass cemented together, and by this
arrangement an image free from colour is obtained.
In addition to ordinary objectives which are designated "dry,"
another series is manufactured termed "immersion." When
using these a drop of water is placed between the cover-glass
and the front lens of a " water-immersion " objective, or a drop
of cedar-wood oil in the case of an "oil immersion." The object
of using an immersion lens is to bring a larger cone of rays into
the objective. Light in its passage from the cover-glass to a
dry objective has to traverse a layer of air, and rays of light in
passing from glass to air suffer refraction, that is, they are bent
away from the perpendicular. If, however, a layer of water
which has a higher refractive power than air is inserted between
the cover glass and the front lens, then the rays are not bent
so far away from the perpendicular, and consequently a larger
bundle enters the objective. When a layer of cedar- wood oil,
which has the same refractive power as glass, is inserted in
MICROSCOPICAL AND BIOLOGICAL
329
this way, the rays suffer no refraction at all ; they continue
straight along in their course, and consequently a still larger
bundle enters the objective. This increases the angle of the
objective and gives better- illumination. Owing to the oil
employed being of the same refractive power as the cover-
glass, an oil immersion is independent, within wide limits,
of the thickness of the cover-glass, and for this reason such
objectives are called "homogeneous." Many objectives, other
than "homogeneous," are provided with what is called a
"correction collar," by means of which the upper pair of
lenses can be removed nearer or farther from the remaining
lens by turning a collar (fig. 83, A and B). This arrange-
FIG. 83.
ment is for making a correction for the thickness of the cover-
glass employed.
Within recent years a new series of lenses have been introduced
termed le apochromatic," these being constructed, by means of
the most careful mathematical calculations, of special kinds of
glass and of a lens of the mineral fluorite ; they are, however,
exceedingly expensive. They possess one marked advantage,
viz., they can be used with eye-pieces of very high magnifying
power. Thus \ inch objective may be used with an eye-
piece magnifying 27 diameters, which gives an enlargement of
1080 diameters, as well as with an eye-piece magnifying only 2
diameters, or with any other eye-piece intermediate between
these two. This, which gives magnifications of from 80 to 1080
by simply removing the eye-piece, saves trouble in changing
objectives.
In differently constructed microscopes the mechanical and
330
THE BREWER'S ANALYST
lense arrangements, as will be seen, vary greatly ; the Abbe
condenser may be of ordinary or apochromatic lenses, and may
be separately employed ; the iris diaphragm may also be
used separately, or both the condenser and iris may be combined.
When apochromatic lenses are employed, compensating eye-pieces
may be used ; and these may or may not also possess an iris
diaphragm (fig. 84) and numerous other advantageous mechanism
which go to increase the cost of the instrument. Many of these
improvements, although necessary in advanced microscopy, are
entirely unnecessary for the brewer's work ; and, as before stated,
a really good instrument, both from the two essential points
mechanical and optical can be obtained at
a price within the range of all.
Lastly, the various magnifying powers of
the eye-pieces are denoted in England by
the letters A, B, and C, etc., beginning
with the lowest power; the B is, however,
most commonly employed, as it is a mistake
to use too high a power. On the Continent
the eye-pieces are denoted by numbers 1,
2, 3, etc. The length of the tube adopted
in Continental instruments is 6 inches, in
English 10 inches, and the Continental and
English objectives are corrected for these
lengths of tubes. Many English microscopes
are now, however, made with a 6 inch tube, and a draw tube
(graduated) to permit its extension to 10 inches, so they can
be used wiih either make of objective. With a microscope
having a 10 inch tube, the total magnifying power of any
combination is found by multiplying the magnifying power
of the objective by that of the eye-piece. Thus, with an
eighth of an inch objective, which magnifies 80 diameters, and
an eye-piece magnifying 5 diameters, we obtain a total magni-
fication of 80 x 5 = 400. With a 6 inch tube the magnifying
power is found by the formula
Objective power x eye-piece power x tube length
10
With the before-mentioned combination this would equal 240
diameters ( 80 ** X 6 ).
FIG. 84.
MICROSCOPICAL AND BIOLOGICAL 331
THE SCHIZOMYCBTBS, HYPHOMYCETES, AND SACCHAROMYCETES,
OR BACTERIA, MOULDS, AND YEASTS.
THE SCHIZtDMYCETES OR BACTERIA.
All bacteria are extremely minute in size, and although there
are hundreds of different species, they nevertheless show but
three general forms, which by De Bary have been aptly com-
pared to billiard-balls, lead-pencils, and corkscrews.
Spheres, rods, and spirals represent all forms. The spheres may
be large or small, and may be long or short, thick or slender;
the spirals may be loosely or tightly coiled, and may have only
one or two or may have many coils, and they may be flexible or
stiff ; but still rods, spheres, and spirals comprise all types.
In size there is some variation, though not very great ; all are
extremely minute, and never visible to the naked eye. The
shapes vary, the diameter of round cells or transverse section of
cylindrical ones being generally about 1 /A ; l the length of
cylindrical cells is not commonly more than 2 to 4 times their
transverse section, although some cells may attain a diameter
as great as 4 /* and occasionally grow to a great length.
The rods may be no more than 0*3 /x in diameter, or may be as
wide as 1*5 /A to 2 '5 /A, and in length vary all the way from a
length scarcely longer than their diameter to extremely long
threads. About the same may be said of the spiral forms.
Many bacteria possess the power of locomotion, but this is
almost exclusively confined to the bacilli and spirilla, only one
motile micrococcus, the Micrococcus agilis, being known. The
motion is brought about by means of a flagellum, lash or cilium,
which they possess at one or both ends or all over their bodies.
These nagella keep up a lashing to and fro in the liquid, and the
lashing serves to propel the bacteria through the liquid.
During their growth they do not bud as do the yeasts, but
multiply by division, and this is the one distinguishing mark
which separates the bacteria from the yeasts.
In addition to their power of reproduction by simple division,
many species have a second reproductive method by means of
spores.
1 English measurements are frequently given in -nn^th of an inch, whereas
foreign measurements are in unnsth of a millimetre or micromillimetre (/*), as
it has usually been called. As physicists and electricians have used the word
micromillimetre to indicate the millionth of a millimetre, the term micron
has been suggested to express the thousandth of a millimetre, and the word
has been adopted by the Royal Microscopical Society.
332 THE BREWER'S ANALYST
The following are those most frequently met with by the
brewer :
Coccus or Micrococcus (including chains of Micrococci)
Sarcina.
The viscous ferment.
Bacterium aceti.
Pasteur ianum.
'xylinum.
Micro bacteria (short rods)
Bacterium lactic.
termo.
Pasteur's lactic ferment.
butyricum or colstridium.
butyricum and B. amylobacter.
Desmo bacteria (including long and short chains)
Bacillus subtilis.
ulna.
,, leptothrix.
Spiro-bacteria (spirals)
Spirillum tenue.
,, undula.
Sarcina. Lindner, who found sarcina in yeast, and using
Hansen's moist chamber and gelatine mode of cultivation with
decoctions of chopped hay or malt extract, infecting these from
various sources, managed to separate and identify several kinds
of sarcina of which two varieties are shown (Plate IX., fig. 85,
Pedioccus acidi lactici, and fig. 86, Sarcina maxima}.
The former is sometimes found in beer and gives rise to a con-
siderable quantity of lactic acid. The diameter of the single
coccus = 0'6 ft to 1 //,. The latter, packet form, is sometimes met
with in malt mashes and wort. Diameter, 3 yu, to 4 p.
Sarcina bacteria belong to the slow-growing type ; they develop
most in wort, in the absence of vigorous yeast, and are found in
beer stored for a lengthy period. Low temperatures do not
destroy their development. They may multiply to such an
extent that the beer becomes ropy, but with rapid consumption
and mean temperature they do not cause much trouble.
The VISCOUS Ferment. Pasteur speaks of the viscous state
of wort and beer, and describes a special ferment (Plate IX., fig.
87) which transforms certain sugars into a kind of gum, together
with mannite and carbon-dioxide.
The amount of gum produced does not stand in constant
MICROSCOPICAL AND BIOLOGICAL 333
relationship to the sugar decomposed ; it is therefore concluded
that there are different viscous ferments, one of which forms only
gum. Very little is known of the ferment or ferments, and it is
believed by some that the viscosity in liquids, supposed to be
formed by one or more special ferments, is, on the other hand,
caused by the excreta of bacteria.
Bacterium aceti. Mycoderma aceti, Bacterium aceti, or
"Mother of Vinegar," as it is variously called, is the organism
employed in vinegar factories for impregnating worts intended to
be turned into vinegar. The appearance of a film or pellicle on
the surface of a liquid is a very ordinary accompaniment of its
growth. Plate IX., fig. 88, shows the organism as depicted by
Pasteur ; it will be seen in the characteristic chain and diplo-
coccus form, the smaller dimension of the latter being about 1 //,.
Iodine colours, B. aceti, yellow.
Adrian Brown made a very careful investigation of B. aceti,
taking every precaution to obtain pure cultivations. He
described it as forming a greasy pellicle, inclined in the early
stages of its growth to climb up the moist surface of the contain-
ing vessel. The liquid below the pellicle is usually turbid from
suspended cells.
In liquids free from oxygen it does not increase, but keeps
alive for a long time. It forms figure 8 cells 2 /x long, united
in chains of varying length, and sometimes the chains are com-
posed of distinct cocci. Brown observed abnormal or involution
forms 10 ft to 15 /u, long, and of a dark gray colour. The shorter
rods of cells, when floating freely in a liquid, are motile.
The organism is found in returned and unsound beers and
yeast, free exposure to air being the determining factor of its
growth. It is also found in bottled ales, sometimes appearing as
a film, due to imperfect corking ; and often when precautions are
not taken to keep the bottles upside down or lying on their
sides for some time after filling with beer, so as to allow the beer
to absorb the air which would otherwise remain between the cork
and the surface of the beer.
A very small quantity of B. aceti produces marked acidity in
beer, and there is no mistaking the presence of its product, viz.,
acetic acid, with its highly pungent smell.
Bacterium Pasteurianum. The above name was given by
Hansen to a form of micrococcus which has the same appearance
as B. aceti ; which produces acetic acid, and only differs from it
in the sense that it gives a blue coloration with iodine.
Bacterium xylinum. This ferment was discovered by
334 THE BEEWER'S ANALYST
Adrian Brown, who describes it as being identical with B. aceti.
It produces acetic acid, and during growth forms a membrane of
cellulose, which sometimes floats on the surface of the liquid. If
shaken down, a fresh film is produced from time to time. This
appears to be the only form in which the ferment develops,
though the membrane may in some cases be dispersed through
the liquid, having the appearance of gelatine finings. Viewed
microscopically, the ferment shows itself in lines embedded in a
transparent, structureless film ; the bacterium appears as rods
about 2 fji in length, several often being united together.
Sometimes the organism is seen in the micrococcus form, which
may possibly be spores; also in long twisted threads 10 ^ to 30 /x,
in length, of a Leptothrix nature. It does not exhibit the large
swollen involution forms of B. aceti.
Lactic bacteria. The lactic bacteria, of which there appear
to be several species, resemble B. aceti in so far as the cells are in
the form of the figure 8 ; but whereas the latter generally form
long chains, and only occasionally are distinct cocci found, the
former generally occur as distinct small rods contracted as a rule
in the middle, forming the figure 8, 2 /* to 3 /x, in length.
They are seldom seen in long chains, although they may
appear in this form, and it is not unusual to find two or three
individuals together forming a small chain. The single rods
are motile.
The action of the ferment is the production of lactic acid which,
although not imparting any distinct flavour, as is the case with
B. aceti, produces an intense acidity. Small quantities of lactic
acid (1*5 per cent.) retard alcoholic fermentation. Plate IX., figs.
89 and 90, show the ferment first described by Pasteur.
Bacterium termo. Plate IX., fig. 91, is a typical example of
organisms of this class. Whenever a vegetable or animal infusion
is left exposed to the air for a short time, this organism, together
with others very similar in appearance, invariably make their
appearance. They are all motile, having a cilium or flagellum
at each end. They have the appearance of small cylinders, each
possessing a central constriction giving the figure 8 appearance,
and about 1*5 /x to 2 /x long.
Fortunately for the brewer, B. termo, like several other organ-
isms to which Hansen gave the generic name of "wort bacteria,"
is only able to thrive in unhopped wort. The bactericidal action
of the soft resins of the hop completely arrests their growth and
development.
Bacterium butyricum. This organism, also known as
Bailey's Brewer's Analyst.]
* [PLATE IX.
FIG. 85. Fed. acidi lactici.
^V^. (After Lindner.)
FIG. 86. Sarcina maxima.
t-V-ft. (After Lindner.)
FIG. 87. Viscous Ferment.
4 r. (After Pasteur.)
FIG. 88. Bacterium aceti.
A ^. (After Pasteur.)
FIG. 89. Lactic Ferment.
(After Pasteur.)
FIG. 90. Bacterium lactis.
3 4. (After Pasteur.)
FIG. 91. Bacterium termo.
(After Cohn. )
[To face p. 334.
336 THE BREWER'S ANALYST
protection. The hay bacillus is therefore a negligible quantity in
the brewery.
Bacillus ulna. This organism, described by Cohn, occurs in
long or short, but very broad, cylinders or threads, 2 /A broad, and
in a free growth as much as 10 /A long. It is frequently found in
infusions such as white of egg. It is occasionally found in yeast
and also in beer, but it does not grow in the latter. Plate X., fig.
94, shows the ferment.
Bacterium leptothrix. Appears as long threads, sometimes
of great length, and twisted on themselves. It is found in the
slime of pipes and wherever filth is allowed to accumulate, and
may often be detected in putrifying sweet wort. It has not been
greatly studied, and is possibly only a particular form of B. subtilis
(Plate X., fig 95).
Spirillum tenue and undula. These organisms are common
in rapidly putrifying liquid and moist substances. Sp. tenue has
been met with in returned sour ales, and once or twice in forced
samples, and both forms in decomposing sweet wort and in water.
Sp. undula has also been met with in putrid grains, and slime from
pipes and the dripping from water-pipes.
Sp. tenue is about 1 /* thick and 4 ^ to 15 /JL long. Sp. undula
about 1*4 p thick and 8 yu, to 12 /x long.
Both are looked upon by many investigators as the same species,
but the latter has wider spirals and an active movement (Plate
X., figs. 96 and 97).
Numerous other bacteria are known, but sufficient has loeen
detailed to give the reader a fair general knowledge of the
bacteria, and to show the significance of strict control in regard
to brewery cleanliness and germ-laden air-exclusion.
THE HYPHOMYCETES OR MOULDS.
The hyphomycetes or moulds, commonly called the fungi, are
flowerless and leafless plants devoid of chlorophyll (which produces
the ordinary green tints of other vegetables), and they fructify by
means of cells separated from the tip of certain filaments, or pro-
duced within the cavity of the protoplasm. They derive nutriment
from the substances on or in which they grow. It is their natural
office to promote chemical change in organic structures, and to
some extent in inorganic matter as well. They are therefore found
accelerating decomposition ; according to ignorant belief, springing
from it. They are fertilising agents, providing nutriment proper
for phsenogamous plants. They serve as food for innumerable
Baileys Brewer's Analyst.'}
[PLATE X.
FIG. 92. Bacterium
butyricum. f.
FIG. 93. Bacillus subtilis.
(After Cohn.)
FIG. 94. Bacterium
ulna. 4oo_
FIG. 95. Bacterium
leptothrix. - 6 -f-.
FIG. 96. Spirillum
tenue. - 4 -f-.
FIG. 97. Spirillum
undula. 4 -.
FIG. 99. Mucor racemosus.
[To face p. 336.
IT*
/
MICROSCOPICAL AND BIOLOGICAL 337
insects and larvae. They also check exuberant growth, appearing
in many forms as parasites on living vegetable and animal struc-
tures. Some of them offer highly nutritious food to man, and
others contain essences having medicinal and other properties.
The forms in which fungi appear are very numerous, and are
classified into a great many orders and genera ; but the lower order
are commonly called moulds, and over two thousand British
species of them are known.
The mildew which appears on articles of food, and which is
familiar to everyone, is seen under the microscope to be an
aggregation of elegant and perfect plants, infinitesimal in size,
but subject to laws of growth as in higher plants.
Among this vast family of plants, belonging to one class, yet
diverse from one another, there is but one kind that the Britisher
condescends to regard with favour (i.e. the mushroom) ; all the
rest are lumped together in one sweeping condemnation. They
are usually looked upon as vegetable vermin only made to be
destroyed. With the rapid growth of science during the past
two or three decades all this is altered, and whereas in the past
but few eyes could see their beauty, their office unknown, their
varieties disregarded, and in fact hardly allowed a place among
Nature's lawful children, but considered something abnormal,
worthless, and inexplicable they are now being correctly classified,
their office perfectly understood, and their industrial use, just as
with bacteria, found of considerable benefit in the manufacture of
certain articles of commerce.
Fungi are a class of plants governed by modifications of the
same laws that control the development of all other vegetables.
Each species has a separate existence, and its nature, character-
istics, constitution, and inherent properties may vary very greatly
from those of even its nearest congener. Fungi do not, any more
than the bacteria or yeasts, spring up indiscriminately, spontane-
ously, or uncertainly. Each species obeys fixed laws of growth
and development, and is not transmutable into others. Each
species has its own particular locality and habitat, and its
characteristics are precisely definable; nor are these liable to
greater variation than is the case in flowering plants.
The modes by which fungi are fertilised have yet to be dis-
covered. Some are propagated by means of the mycelium to a
certain extent, but the universal method of reproduction is
through the medium of spores, which correspond to the seeds of
flowering plants. These spores are of infinitesimal size, even in
the largest fungi, and are generated in inconceivable multitudes
22
338 THE BREWER'S ANALYST
by each plant. They become productive only when they reach
their proper pabulum. The conditions under which they become
productive have yet to be learnt. These spores are disseminated
in countless myriads by the air, which is ever loaded with them.
Some varieties, for example, it is almost impossible to exclude
from their special nidus. Other kinds are apparently disseminated
by water, by the sap of plants, by the blood and excreta of
animals, birds, reptiles, or insects, and in yet other ways.
The mould fungi occupy a low scale in the vegetable world ;
they are more or less parasitic, and are found on decaying matter
in association with bacteria. They secrete powerful enzymes in
their tissue, by the aid of which they break down and simplify
the complex bodies on which they grow. These bodies in their
turn are seized upon by the bacteria, who thus complete the work
of destruction. The mould fungi do not entirely confine their
attention to the vegetable world, for they often grow and produce
disease in animals and insects. For example, the fungus, Torrubia
militaris, grows on the body of the wasp, and even man sometimes
falls a prey to this organism. The spores of the Aspergillus
fumigatus, taken into the lungs in the act of breathing, adhere to
the inner tissue, vegetate, and produce their mycelium, causing
the disease pneumomycosis ; the patient shows all the symptoms
of tuberculosis, and usually succumbs through inability to absorb
oxygen.
The common mould, Mucor racemosus, will grow in the inner
tube of the human ear, giving rise to otomycosis ; the membranes
of the ear become pierced, and when the nerve centres are reached
frightful irritation, madness, and death result.
Examined microscopically, the mould fungi generally resolve
themselves into an infinity of delicate filaments filled with living
protoplasm often in a state of continuous motion. The filaments
are sometimes simple, more often ramified. Grouped together in
various ways, they constitute what is known as the " mycelium."
The mycelium liquefies and renders assimilable the matter on
which it grows, of which it forms its tissue, and finally produces
the spores. The spores or seeds are produced in marvellous
numbers in the special capsule or " sporangium." Some of the
sporangia contain as many as two million spores. Their forma-
tion is generally effected by an asexual process ; a certain portion
of the mycelium differentiates, becomes more or less spherical, and
the spores are produced by internal cell-division. Certain moulds,
however, exhibit a real sexual mode of reproduction, such as is
met with in the higher forms of vegetable life ; two distinct
MICROSCOPICAL AND BIOLOGICAL 339
branches of the mycelium join together and form a conjugated
sporangium or large spore (zygospore) capable of giving rise to
the mould growth afresh.
The mould fungi, when vgrown on cereals, attack the cellulose
and starchy portions of the grain, transforming them into sugars
which are then oxidised, generally with the production of organic
acids.
They possess the curious property of being able to adapt
themselves to an anaerobic (without air) mode of existence. The
genus Mucor of which the Mucor mucedo, often found growing on
the excreta of herbivorous animals, can be taken as a type, all
exhibit this capacity.
When the Mucor mucedo is placed in a saccharine liquid, a
change comes over the mycelium. Transverse septa appear at
very close intervals in the filaments ; the divisions thus formed
become more and more spherical, and finally, detaching themselves
from the mycelium, swim about in the liquid. They then
reproduce by budding after the manner of yeast; at the same
time an alcoholic fermentation is set up in the liquid. The
amount of alcohol produced during fermentation set up by moulds
does not greatly exceed 3 or 4 per cent., although some species
can produce as much as 8 or 9 per cent.
Such yeast forms or "sprouting colonies" are known in an
astonishingly wide relationship among the fungi. In fact nearly
every one of the large groups is capable of producing yeast forms if
submerged in saccharine liquids e.g., besides many Mucors, species
of Mycoderma, Chalara, Oidium, Torula, and Monilia among the
doubtful Hyphomycetes ; JExoascus, Dothidea, Fumago, Dematium,
Bulgaria, and others among the Ascomycetes ; species of Tremella
and Exob asidium among the higher Basidiomycetes, and numerous
species of Ustilago among the Ustilagineae, all form yeast colonies
under certain conditions. It is owing to this curious behaviour that
the controversy has arisen with regard to the nature of the yeast
plant. Some naturalists have held that yeast is only the bud or
"gemma" form of certain moulds, and it is still believed an open
question as to whether the so-called true yeasts, i.e. the Saccharo-
mycetes, are autonomous forms or merely sprout forms of some
higher fungus.
Every brewer is aware of the danger of mould in either the
brewery or malt-house, and is familiar with at least the common
varieties. In general the moulds are a positive danger, and every
care should be exercised in preventing their appearance or growth
in any part of the brewery or malt-making ^premises. ^Barley,
340 THE BREWER'S ANALYST
during its vegetation on the malt-house floor, is often attacked by
Penicillium glaucum, Mucor mucedo, Aspergillus glaucus, and
other varieties which communicate offensive odours to the grain ;
and although their growth is arrested or their vitality destroyed
at the kiln-drying temperatures, the grain nevertheless contributes
nauseous flavours to the beer brewed from it, rendering such beer
at times positively undrinkable. The same applies to mouldy
hops : the vitality of the mould is undoubtedly destroyed during
the boiling of the wort, but the objectionable flavour is never-
theless imparted to the resulting beer. With hops used for "dry
hopping " the case is perhaps still more important, since here the
mould is not destroyed, and many varieties not only increase and
multiply, quickly turning the beer rancid, but the secreted
enzymes have a marked effect in reducing the residual beer
extract.
During hot weather the mould fungi multiply with remarkable
rapidity, and can frequently be detected on exposed sugar solutions,
wort, etc., left standing for any length of time. They grow rapidly
in beers of low gravity or of low alcoholic strength, when once
they gain access, Monilia Candida being the most prominent
under these conditions.
Odium lactis makes its appearance as a thin white skin on the
surface of beer, and cask plant left unwashed for any length of
time is a fruitful breeding place for several fungi. So also is wooden
plant such as fermenting vessels and storage vats, the outsides and
particularly the bottoms of which not being easily got at for clean-
ing. Such vessels are liable to quickly become covered with mould,
which, if allowed to remain, ultimately destroys the timber. Damp
walls, ceilings, and floors are often seen copiously laden with mould,
and the spores are wafted about by atmospheric currents con-
taminating places which would otherwise not be difficult to keep
clean. There are then, as stated, an endless variety of moulds, all
of which more or less play a significant part and vary in their
method of reproduction. It will be sufficient, however, to give
brief particulars of a few of the most important common varieties,
emphasising the point that, with regard to one and all, the brewer
should take every care, by scrupulous cleanliness and antiseptic
treatment, to stamp them out whenever they make their appear-
ance, and particularly to see that his pitching yeast and hops for
"hopping down" purposes are free from such contamination.
The mould fungi have been divided into five orders :
Hypodermii, Phycomycetes, Ascomycetes, Basidiomycetes, and
Myxomycetes.
MICROSCOPICAL AND BIOLOGICAL 341
For a complete account and full details of the various forms of
development, reference must be made to botanical and other
works ; l the following, however, are of special interest to the
brewer :
HYPODBRMII.
Ustilag'O Carbo (Mildew 9 Smut). Spores, brown, circular
episporium, smooth ; sporidia, ovoid cells.
The spores occur as a black powder in the ears and panicles of
wheat, barley, and oats.
Tilletia Caries. Spores, round, pale brown ; episporium with
reticulated thickenings. In germinating, the sporidia grow out
radially from the end of the promycelium ; these, at their lower
part, conjugate by a cross branch and separate from the pro-
mycelium, and at some point of the pair a hypha grows out, on
which abundant secondary sporidia develop. The latter are long,
oval cells, which can in turn germinate. The fungus occurs in
the form of a stinking powder in grains of wheat, which renders
the meal impure and gives it a disagreeable smell.
Urocystis OCCUlta. The spores consist of several cells united
together : partly, large dark-brown cells in the interior ; and
outside, several flat, semicircular, colourless cells. The pro-
mycelium germinates as in Tilletia, but the cylindrical cells produce
a hypha, without, as a rule, previous conjugation. They occur
as a black powder in rye-straw in long, disintegrated stripes, which
are at first greyish. The affected plant produces abortive ears.
PHYCOMYCETES.
MUCOF mucedo (Plate XL, fig. 98). A commonly occurring
white mould on rotten fruits, mouldy bread, old yeast, damp
barley, malt, hops, etc. It readily makes its appearance upon
horse manure and other highly putrefactive organic substances,
which it gradually covers with a luxuriant vegetation consisting
of long, delicate, silky filaments (fig. 98, a, a) each of which ends
in a small rounded head. The body of the plant consists of a
number of branched filaments (b, b, b, b) or hyphae. Some of
these ramify into the substratum on which the fungus grows, and
the mass so formed is termed a " mycelium."
The mycelia of contiguous plants interlace with each other and
form a felted mass. The plant, until the period of spore formation,
consists of a single cell formed externally by a thin, much
1 Sachs, Text-book of Botany ; Jorgensen, Micro-organisms of Fermentation.
342 THE BREWER'S ANALYST
branched tube of elastic, transparent, and colourless cellulose.
The inside of this tube is more or less completely filled with
protoplasm permeated by the cell-juice, and this latter, collecting
at various points, forms vacuoles.
The study of the appearance of the spores and their growth
during vegetation is effected most conveniently by taking up
with a piece of platinum wire a mass of sporanges of a growth of
the fungus. A sporangia (fig. 98, c) is taken up on the wire,
and no matter how few spores are collected by the wire, there
will be far more than is required for the impregnation of a liquid.
A little sterilised and cooled wort is now taken in a watch glass
and the wire containing the sporangia used to stir up the wort,
by which the sporangia not ruptured spontaneously are ruptured
by the stirring. The watch glass is now covered and allowed to
stand for one hour, after which the wort is again stirred so as to
distribute the spores. From the wort one or more hanging-drop
cultures are now made, taking care that each drop does not
contain more than one or two spores. The culture is then placed
under the microscope and its progress watched from hour to hour.
In course of time it will be noticed that each spore has swelled
to about ten times its original size, has become circular, and
developed a large vacuole. In the course of a few hours the
spore pushes out one or two buds, which gradually increase in
length and become hyphse. The plant, during this development,
absorbs more nutriment from the wort than is required to supply
the energy necessary for its vital functions, and consequently an
accumulation of substances takes place in its interior. Space is
provided for this accumulation by the hypha increasing in length,
and afterwards by its throwing out side branches. When the
lengthening process has proceeded for some time, the membrane
at some point on the side of the tube is pushed out by the proto-
plasm forming a bud which gradually enlarges to form a hyphal
branch. This growth and subdivision of the hyphse goes on until
the many-branched mycelium is formed.
In old plants there is a tendency for the hyphse to become
divided into distinct cells by the formation of partition walls, as
is the normal course with many other mould fungi.
In the course of speculation, the plant in time puts forth at
various points upright hyphse which are termed "aerial hyphse"
(fig. 98, a, a), their function being to bear the organs of fructi-
fication. Upon each of them attaining a certain length they
cease to grow, and the upper ends become swollen into a small
cell, the " sporangium," on which minute drops of water appear.
MICROSCOPICAL AND BIOLOGICAL 343
This water is not condensed on the plant, but is actually passed
through the membrane by osmotic pressure. A pautition now
commences to form at the junction of the cell with the stem, the
end of which assumes the form of a knob, called the " columella,"
situated within the cell (fig. 98, d).
A portion of protoplasm is in this manner cut off from the
remaining portions of the plant, which, apart from its complicated
figure, had up to this period consisted of a single cell.
The exterior of the sporangium becomes covered with minute
spicules of calcic oxalate, which give it a granulated appearance.
The protoplasm in the sporangium now becomes marked out into
a number of oval masses, which, though close together, do not
actually touch. These eventually become invested with a
membrane, and gradually develop into perfect spores (c). The
rest of the protoplasm, which is not used in forming the spores, is
then transformed into a gelatinous substance.
The sporangium, which in its early period of growth is of a pale
colour, gradually, as it ripens, turns first to brown, then to black,
its outer wall at the same time becoming thin and brittle.
When the sporangium is ripe, the contained gelatinous matter
absorbs water, swells up, and the cell wall bursts, resulting in the
spores being scattered in all directions.
The interior knob or "columella" (fig. 98, /) remains attached
to the end of the aerial hypha for some time, often with a portion
of the covering of the sporangium attached, which forms a small
collar round its base.
The detached spores are now wafted about by air currents
until they by chance come in contact with a suitable nutritive
medium, in which case they germinate and form new plants of
the fungus.
Like all other low members of the vegetable kingdom, the
mucors exhibit a method of reproduction common to the higher
forms of plant life ; that is to say, by sexual influence. In
this form two cells, the male and the female, are concerned, the
process of reproduction being in consequence called "sexual."
So long as the mucor vegetates on the surface of a nutritive fluid,
it propagates in the asexual manner ; but when grown on a solid
substratum, as is invariably the case in its natural state, it then
reproduces itself in an entirely different manner. When repro-
duction is about to take place, two short club-shaped branches
grow out from contiguous hyphse which become filled with proto-
plasm and gradually approach one another until their extremities
touch. A cell wall, which cuts off a portion of protoplasm from
344 THE BREWER'S ANALYST
that of the branch, now develops in the end of each of these short
branches. The cell walls which are in contact now dissolve, and
the contents of the two cells fuse together (fig. 98, y) and then
grow into an enlarged cell called a " zygospore " which, as it
ripens, turns black, its exterior becoming covered with excres-
cences. The zygospore now becomes detached from the rest of
the plant, and when placed in a suitable medium commences to
germinate after the lapse of six or eight weeks. This lengthy
time taken in commencing germination has led to the term
"resting-spores," which is also often applied to bacteria and to
barley, which is capable of germinating after the lapse of hundreds
of years. It is apparently a provision of nature to tide the plant
over a period of scarcity of food, for resting-spores are, as a rule,
only formed when the supply of food runs short.
On germination the cell wall of the zygospore (fig. 98, h)
ruptures, and an unbranched hypha grows from it which sends up
an upright stem at the extremity of which a sporangium is
formed (fig. 98,.;'), the spores of which, when ripe, escape, and
reproduce the plant in an asexual manner.
The mucor does not form gemmae as does Mucor racemosus, but
its mycelium when submerged in wort is able to excite a feeble
alcoholic fermentation yielding, according to Hansen, in about
3 months, 1 per cent, of alcohol by volume, and in 6 months,
3 per cent. This power of causing fermentation is greater in
those mucors which form gemmae.
Mucor raeemosus (Plate X., fig. 99, and Plate XL, fig. 100).
Hyphae upright, short, and branched in some instances ;
sporangia yellowish to pale brown or grey ; columella round
or pear-shaped ; spores round or nearly so. The external portion
of the sporangium is tough and insoluble in water. The fungus,
as regards nutrition and reproduction, resembles Mucedo. It
nevertheless has a third method of reproduction, which has not
been observed in all the other members of the same family, viz.,
by the formation of gemmae. When this is about to take place,
the protoplasm in some of the hyphae of the mycelium collects at
certain points in the tube; transverse walls then form, dividing
these portions from the rest of the contents of the tube, con-
verting them into distinct cells. The cell walls then thicken,
the intermediate portions of the hyphae decay, and the gemmae
become detached : each of these, under favourable conditions,
develops into a new plant.
When the gemmae are submerged in a saccharine liquid they
set up alcoholic fermentation and throw out buds of a spherical
Bailey' 's Brewer's Aii.a?t/sf.]
[PLATE XI.
Q
J\
\
n
FIG. 98. Mucor mucedo. (After Brefeld and Kny.)
a, a, Aerial hyphse ; b, b, branched hyphse (mycelium) ; c, sporangium ; d, columella :
e, spores ; /, columella ; g, cell-fusion ; h, ruptured zygospore ; /, formation of
sporangium.
FIG. 100. Mucor racemosus (submerged.)
[To face p. 344.
MICROSCOPICAL AND BIOLOGICAL 345
or ovoid shape which often hang together in strings or clusters
and bear a strong resemblance to yeast (fig. 100) ; they produce
as much as 7 per cent, by volume of alcohol, and secrete an
enzyme capable of inverting., cane-sugar. It is the only mucor
capable of this inverting action.
Other Mueors: Mucor stolonifer (Lichtheim). Mycelium
grows in the air and then bends down and re-enters the nutrient
substratum ; sporangia black, and spores globular.
MUCOP CireinelloideS. Branching of the aerial hyphse ; the
small branchlets bearing the sporangia become considerably
curved during development. Like Mucor racemosus, it forms
gemmge. It secretes an enzyme capable of fermenting invert-
sugar, but is unable to invert or ferment cane-sugar.
MUCOP ereetus resembles Mucor racemosus, but has, like
Mucor spinosus, spicules on the top of its columella. When grown
in the submerged condition it yields, in a wort of a specific gravity
of from 1056 to I860 , as much as 8 per cent, of alcohol by
volume : it can ferment dextrin. The fungus also secretes an
enzyme capable of hydrolysing starch.
MllCOr SpinOSUS has a chocolate-brown sporangia, and the
upper portion of its columella is studded with pointed excrescences.
When grown under similar conditions as Mucor erectus, it yields
5*5 per cent, by volume of alcohol.
Mucor asperglllus (Lichtheim). Fruit-hyphse thinned at
the base, and with many fork-like divisions ; dark-brown spores.
Mucor phycomyces (Lichtheim). Mycelium, thick- walled ;
olive-green fruit-hyphse ; black sporangia, and oblong spores.
Mucor macroearpUS (Lichtheim) Spindle-formed, pointed
spores.
Mueor fusiger (Lichtheim). Ovoid spores.
ASCOMYCETES.
Oidium lactis (Plate XII., fig. 101). Fruit-hyphse, simple,
erect, and colourless, bearing at their ends a series of chain of
conidia. In some cases the fruit-hyphse branches beneath the
chain of spores. Spores are short cylinders. The conidia
germinate into filaments of varying length, which by subdivision
form septate mycelial hyphee : these and their branches give rise
in turn to spores or conidia. The fungus is deeply stained by the
ordinary aniline dyes. In a plate cultivation the colonies appear
as white points, and develop into delicate, stellate colonies which
ultimately coalesce and form a fine mycelial network covering
346 THE BREWER'S ANALYST
the surface of the gelatine. The gelatine is not liquefied. The
growth on the surface of agar is similar to that on gelatine. The
fungus appears plentifully in sour milk.
Aspergillus glaueus (Eurotium aspergillus glaucus). My-
celium at first whitish, becoming grey-green or yellow-green;
spores grey-green, thick- walled. It is found on various substances,
chiefly fruit.
Aspergillus nigfer (Eurotium aspergillus niger, De Bary).
Dark chocolate tufts; conidia round, black-brown or grey-brown
when ripe. The mould can be cultivated readily on bread
moistened with vinegar, on slices of lemon, and on acid fruits and
liquids.
Aspergillus nidulans. Bread and potatoes acquire a reddish-
brown colour.
Penicillium glaucum (Plate XII., fig. 102). Occurs as a
white, and later a blue-green mould, on which dew-like drops of
liquid sometimes appear. Its spores are present in large numbers
in the air, and are liable to contaminate cultivations. The fruit-
hypha bears terminally a number of branched, cylindrical cells,
from which chains of a greenish conidia are developed.
It is the commonest of all moulds, and most frequently met
with during malting operations.
THE SACCHAROMYCETES OR YEASTS.
Yeast, when microscopically examined, is seen to consist of a
number of round or oval bodies, either isolated or joined together
in groups, and varying in length from 3 ^ to 10 /x, (Plate XIII.,
figs. 103 and 104).
An idea may be gained as to the minuteness of the cells from
the fact that a straight row of some 3000 would only equal 1
linear inch, and that the number of cells in 1 ounce avoirdupois
of dry-pressed yeast equals about 60,000 millions.
Each separate body is an individual plant which consists of a
single cell, surrounded by a thin, transparent cell wall of cellulose
or some such closely allied substance.
The interior of each cell is almost completely filled with proto-
plasm, which in some cells is distinctly clearer than in others.
These clear portions are called the vacuoles, and are considered to
have their origin mainly in the withdrawal of nutriment from
the protoplasm of the parent cell during the reproductive process ;
the protoplasm being replaced by transparent cell-juice, as Reess
terms it, probably of a more aqueous nature than the rest of
Bailees Brewer's Analyst.}
[PLATE XII.
FIG. 101. Odium lactis.
(After Reess. )
FIG. 102. Penicillium glaucum.
( After Maddox.)
[To face p. 346.
MICROSCOPICAL AND BIOLOGICAL 347
the protoplasm. At the same time it is by no means certain
that the vacuoles cannot appear and be well marked apart from
this action. In any case their appearance is very much influenced
by varying conditions of temperature and aeration where repro-
duction does not take place.
Healthy cells usually show at least one vacuole, but often two,
and sometimes three. Inside the vacuole may be seen small
granules, and these not infrequently move actively in the clear
protoplasm.
" Stone square " yeast and specimens of London yeast show
this very plainly. The granules are called nuclei. On examining
full-sized, well-vacuoled cells carefully, a dark spot called the
nucleus may be frequently detected which, on causing the cell to
shift its position by touching the cover-glass, pressing it slightly,
or in some other way imparting movement, is seen to lie on the
cell wall. This is the point at which the bud is appearing when
the yeast is in course of reproduction. The nucleus is by no
means such a prominent object as it is in most vegetable cells,
but it can be rendered visible by staining with osmic acid or
haematoxylm and picric acid. Ac^wttt|p to Jansens, the nucleus
of the yeast cell divides previous td tfys division bf the protoplasm
of the cell taking place, eittier'irij^he lormtitioii of a new bud
or of spores.
The cell wall is an integument" -which, although thin, has con-
siderable elasticity and resisting power. It may, however, be
burst by a sudden shock, such as a blow upon the cover-glass,
when the protoplasm will be seen to have emerged from the sac.
If a little staining agent, such as indigo, is run under the cover-
glass, the dead protoplasm of the ruptured cells will take the
stain freely, while those of the majority of the unruptured cells
remain uncoloured. This rejection of staining matter is peculiar
to living protoplasm, for their substance when dead exhibits a
powerful attraction for many dyes. The number of dead cells
in a sample of yeast may be readily detected by this curious
difference in the behaviour of living and dead protoplasm.
Yeast possesses no chlorophyll cells, and cannot therefore
obtain the carbon necessary for its nutrition from the carbon-
dioxide dissolved in the liquid. This constitutes the main
distinction between plants which bear chlorophyll cells and the
fungi, to which yeasts belong, which do not. Carbon must be
supplied to them in the form of a substance, such as a carbo-
hydrate, which they are able to assimilate. The fungi, being
devoid of chlorophyll cells, are dependent upon those plants which
348 THE BREWER'S ANALYST
bear chlorophyll cells for their supply of carbonaceous food, and
in this respect they resemble animals. In brewing operations the
yeast obtains its carbonaceous food supply from the transformed
starch which has been originally manufactured by the chlorophyll
cells of barley or other starch cereal.
The protoplasmic content of the yeast cell contains nitrogen ;
this element must also be supplied to the plant in the form which
it can assimilate, and yeast manifests certain peculiarities in this
respect. The chlorophyll-bearing plants generally are able to
derive their supply of nitrogen from a nitrogenous compound of a
purely inorganic nature such as potassium nitrate, but the yeast
plant is quite unable to do this. If, however, ammonium nitrate
is substituted for this salt, then the yeast increases and multiplies,
showing that its wants in this direction are satisfied.
The following shows the chemical composition of yeast, which,
however, varies greatly in different samples :
Cellulose . . . . 43 - 3 per cent.
Proteids or albuminoids . . 44 - ,,
Fat 3-9
Extractive matter . . 2 '5
Ash 6-3
The ash being composed of the following :
Potassic phosphate . . .72-6 ,,
Magnesic ,, ... 19'4 ,,
Calcic . 6-2
Silica, etc 1*8
Yeast has two distinct methods of reproduction ; the first of
these, that is, by budding, is by far the more usual one ; hence
the name "Budding Fungi," which is often applied to the
members of this class. The second, and less usual 'method, is by
the production of spores, which form in the interior of the cell.
There are numerous species and varieties of yeast.
Formerly the yeasts were classified as species according to the
differences in their appearance when microscopically examined.
Those of a more or less spherical shape were termed Saccharomyces
cerevisice those of an elliptical form, Saccharomyces ellipsoidcus ;
those of a sausage-shape form, Saccharomyces Pastorianus.
No method of distinguishing the species of yeast from its shape
alone can, however, be relied upon, as each species is able, under
different conditions of cultivation, to assume the forms of others.
The typical examples of brewery yeasts shown from different
Bailey's Brewer's Analyst.]
[PLATE
FIG. 103. Burton Yeast.
FIG. 104. London Yeast.
[To face p. 348.
MICROSCOPICAL AND BIOLOGICAL 349
centres are therefore only cited as examples of what is usually
obtained in practice, and that the different methods of fermenta-
tion, combined with the character of the saline and other food
supplies under normal practical conditions, stamp the physical
appearance of a yeast to a great extent.
Although the majority of yeasts are able to ferment the two
sugars glucose and levulose which require no previous inversion,
it is not the case with the disaccharide sugars, maltose, cane
sugar, and milk-sugar.
Yeasts such as S. apiculatus do not secrete an inverting enzyme,
hence they are unable to ferment any of the disaccharides.
Other yeasts, such as S. albicans, are able to invert and ferment
maltose, but not cane-sugar. The S. kefir can invert and ferment
cane-sugar and milk-sugar, but not maltose. Some yeasts, such as
S. Ludivigie, are unable to transform any of the sugars into alcohol,
but appear to produce oxalic acid instead.
These distinctions are also found in the mould fungi, and their
ability to ferment the various disaccharides, or the reverse,
depends upon the same causes. Monilia Candida, for example,
secretes invertase.
In addition to invertase, , the" majority of yeasts, that is to say,
the cultivated yeasts, secrete glucase, which, previous to its
fermentative action, converts maltose into glucose. Others have
the power of degrading a greater or less number of the inter-
mediary dextrins combined with maltose and known as malto-
dextrins, which occur in wort, and to this is attributed the
difference observable in the attenuative powers of the various
yeasts. Again, numerous varieties impart objectionable flavours
to beer.
Staining*. Lastly, when examining bacteria, moulds, or yeasts,
these minute organisms require some means to be used for rendering
their presence more visible under the microscope than when seen
in their natural state, and to distinguish them from minute
inorganic particles or amongst diseased or healthy tissues ; hence
some process of staining is generally adopted, and by preference
the various aniline dyes are employed.
They easily take the stain of methyl violet, gentian violet,
methyl blue, aniline brown, chrysoidin, magenta, rose aniline,
etc. ; and also osmic acid, iodine in iodide of potassium, and
sundry other stains. The blue colours are, however, most
valuable and more generally employed as easily differentiating
these organisms, whilst iodine is of special value in detecting
starch.
350 THE BREWEK'S ANALYST
BIOLOGICAL.
First we have to consider the means that have been devised for
isolating different organisms, since, in order to study the character-
istics of any one of them, we must first be able to handle it either
alone or at any rate in a fairly isolated condition.
The foundation of the experimental demonstrations of Schwann
and of Pasteur lies in the fact that the living protoplasm of nearly
all micro-organisms is destroyed that is to say, undergoes an
irrevocable chemical change when subjected to a temperature
slightly below or above that of boiling water. Consequently it
is possible, by the action of heat, to destroy the micro-organisms
present in an experimental vessel and its contents, and to protect
the contents from the further accession of organisms. By this
method, and by this method alone, it has been possible to prepare
organic infusions, as well as solid gelatine, albumin, etc., which,
while capable of supporting the life of organisms, are yet free
from their presence for the time being. Such substances are said
to be " sterilised," that is to say, we partly fill flasks with wort,
meat extract, or other nutritive solution, boil the same, and
immediately close the flasks so that atmospheric air may not gain
access, and the fluid contents will then keep sound indefinitely.
We may, on the other hand, prepare solid gelatine or albumin
in a similar manner, since these substances being liquid when hot,
solidify when cold, so that we have only to add them to flasks or
tubes, raise them to the boil, and similarly close the flasks or tubes
to prevent further access of the atmosphere and its contained germs.
In numerous cases, however, we do not require to keep the
flasks or tubes so closed, but on the contrary wish for pure air to
have access to the contents. In such cases we plug the flasks
with sterilised cotton wool or sterilised asbestos, so that the air is
filtered and the germs kept back, only pure (germless) air gaining
access.
This may also be performed by heating the air or passing it
through chemical solutions before allowing it to enter the flasks.
We have only then to inoculate these flasks with bacteria, moulds,
or yeasts to obtain growths apart from aerial contamination, but
a stride further than this is to isolate the organisms so as to
inoculate the sterilised nutrient with a special individual organism
and obtain its growth independently from any other.
Pasteur was the first to suggest a method by which this could
be performed, the idea having occurred to him in his endeavour to
test the vitality of yeast.
MICROSCOPICAL AND BIOLOGICAL 351
A few grams of powdered yeast were rubbed up with five times
their weight of sterilised plaster of Paris in a sterilised mortar.
The mixture was then wrapped up in a piece of sterilised paper
and dried at a temperature of 68-77 F. (20-25 C.). Two
days afterwards a pinch of this powder was sown in sterilised wort
contained in a Pasteur flask, and in three days signs of fermenta-
tion made their appearance in the wort. When the yeast was
two and a half months old the experiment was repeated ; this
time fermentation commenced on the fourth day, hence the
vitality of the yeast was not destroyed, but merely somewhat
lowered.
In a similar experiment made with the same yeast when seven
months old, the vitality was not altogether lost, but was still more
depressed, for it took eight days for signs of fermentation to
appear. At the end of ten months the yeast, when again treated
in this manner, was found to be completely dead ; the wort
impregnated with it, though observed for several months after-
wards, gave no sign of fermentation.
From this followed a method by which it became quite possible
to artificially impregnate the air of a room with yeast organisms.
In order to effect this it was only necessary to drop a small
quantity of the dried yeast powder from a height, when the
presence of living yeast in the air of the room could be demon-
strated by opening a series of vacmim flasks in it.
It often happened, in experimenting in this manner, that one
flask received but one organism ; and in this way a pure culture of
a single species of yeast was obtained, since the whole of it must
have sprung from the mother cell.
At the conclusion of a description of these experiments, Pasteur
adds the following sentence :
"Our preliminary observations, although incomplete, seem to
favour the idea that numerous varieties of ferments are to be
obtained by these means."
Here he distinctly foreshadowed the important field of investiga-
tion which has been, in later years, so brilliantly worked out by
Hansen, and which is hereafter referred to.
The next steps that were taken were more in connection with
the bacterial organisms in the atmosphere than yeasts, and unique
experiments in this direction were devised by Miquel, Koch,
Hueppe, Petrie, Frankland, and others.
Miquel employed, at first, an apparatus which he called an
" aeroscope." In this the air to be examined was caused to
impinge in a fine jet on a glass plate smeared with a mixture of
352 THE BREWER'S ANALYST
gelatine and glucose, which from its sticky nature was eminently
adapted to catch and retain the floating particles which the air
contained. These particles were then evenly distributed over the
glass plate, placed under the microscope, and counted.
Since this method gave no information as to the number of
living organisms contained in a measured quantity of air, he
devised a peculiarly constructed flask in which a measured
quantity of air was caused to bubble through a known quantity
of water. He thus obtained the dust of the atmosphere suspended
in water, which, after being diluted with a quantity of sterilised
wort, was added in small and equally measured proportions to
small quantities of sterilised broth contained in a number of
flasks. When a large proportion of the contents of the flasks
treated in this way exhibited no signs of infection, there was a
probability that some of the flasks contained only a single germ
consequently, by taking into account the quantity of air passed
through the apparatus, and the number of flasks which became
infected, it was possible to form an approximate estimate of the
number of organisms that were present in a sample of air capable
of development.
Koch devised an entirely different form of apparatus. It
consisted of a glass tube about a yard long and two inches bore.
One end of the tube was closed with a perforated india-rubber
stopper, a glass tube plugged with sterilised cotton wool being
inserted in the apparatus in the stopper. A quantity of sterilised
gelatine meat-broth was then introduced into the tube and its
other end closed with an india-rubber cap. The whole was then
sterilised, laid on its side, and allowed to cool. When about to
be used the glass tube was connected with an aspirator, the india-
rubber cap removed, and air drawn slowly through the tube. In
its slow passage through the tube the particles which the air
contained were thus deposited on the gelatine. The india-rubber
cap was then replaced on the end of the tube and the whole
transferred to an incubator, where it was allowed to remain until
the organisms had developed and formed colonies. These were
then counted and their general appearance noted.
A curious fact was observed in experiments conducted in this
manner : the bacterium which had developed was found in that
portion of the tube nearest the end where the air entered, whilst
the mould fungi were found much farther down the tube ; this
apparently showing that the specific gravity of the germs of the
former organisms is higher than that of the germs of the latter.
Hueppe's method consisted in causing the air under examina-
MICROSCOPICAL AND BIOLOGICAL 353
tion to bubble slowly through warm, sterilised, gelatine meat-broth,
which was afterwards spread upon sterilised glass plates. These
were placed in an incubator, and the colonies that formed on the
same were then studied.
Miquel, Petrie, and Frankland's methods consisted in
collecting the floating particles of the air by passing the air
through niters containing such substances as sterilised sand,
powdered glass, glass wool, asbestos, etc. The material of the
filter was then mixed with sterilised gelatine meat-broth and
spread on sterilised glass plates ; or the sand, etc., with the germs
it contained, was placed in a Petrie dish containing gelatine meat-
broth, covered over, and placed in the incubator.
The gelatine meat-broth methods of detecting the origin and
estimating the quantity of the microbes present in the atmosphere,
were shown by Miquel to be far from accurate. He showed that
gelatine meat-broth cannot be used at a temperature higher than
75 F. (24 C.), since above this temperature the gelatine becomes
fluid, and some bacteria require a higher temperature than this
for their development. Many bacteria, again, take a fortnight to
form colonies at the usual temperature of the incubator, and by
this time so much of the gelatine on the plate is liquefied by the
action of certain bacteria, or the plates may be so covered over
with the rapidly growing mould fungi, as to be unfitted for further
observation. Consequently, those organisms which have not had
time to develop entirely escape observation.
Some species of organisms which readily develop in liquids will
not do so on a gelatine plate; and finally, there is no absolute
certainty that one colony only represents one species of organism.
This was demonstrated by growing colonies on a plate in the
ordinary way, then sowing each of them in a separate batch of
meat decoction. A second-plate culture was afterwards made
with each batch of the infected broth; and, as in these latter
colonies species were found which differed from those of the
original colony, distinct evidence was afforded that the original
colony by no means consisted of one species.
These observations all led to more exact methods being devised
which will be understood from the experimental data hereafter
detailed under Fractional Dilution.
The result of Pasteur's observations regarding the germs in the
atmosphere is that "the air of places in individual proximity to
one another may contain at the same time not only the most
diverse organisms, but also the most variable quantities of
them."
23
354 THE BREWER'S ANALYST
The germs of organisms seem to exist in the atmosphere in the
form of clouds, the intervening spaces between which are com-
paratively germ-free. It is, however, now generally agreed that
the number of bacterial organisms present in the air is much
modified by the weather ; they are most abundant in dry seasons,
whilst after a spell of wet weather their number considerably
diminishes. The reverse seems to be the case with the mould
fungi ; these occur in the greater number in the atmosphere in
damp weather, and in much smaller quantity in dry weather,
Hansen, who carried out an extensive series of experiments with
the object of ascertaining the nature and distribution of organisms
in the atmosphere which might exert a prejudicial effect on the
operations of the brewer, showed that the yeasts in the atmosphere
increase in number from June to August, and are most abundant
at the end of August and the beginning of September (the period
of the ripening of fruit), after which their number again decreases.
Hence it is that at this season the wort, when on the coolers and
refrigerators, is likely to receive its greatest contamination from
these organisms.
It will thus be realised that the question of aerial contamination
is one of vital importance to the brewer, and a vivid picture in
this direction is apparent from the experiments conducted by the
late Dr G. Harris Morris, 1 in which it was estimated that the
number of germs falling upon an open cooler amounted to the
enormous number of 142,887 per square yard per hour. The
brewer should therefore avoid aerial contamination as far as lies in
his power, and the analyst should keep a watch upon any undue
contamination, the presence of mould spores or wild yeasts being
immediately checked at all costs. A convenient method of pro-
cedure on the part of the analyst is therefore given hereafter.
The preceding meat-gelatine method of cultivating micro-
organisms having been shown to be unsatisfactory for some
purposes, fresh methods had to be devised.
Nagfeli therefore invented an ingenious method now known as
Fractional Dilution, which consists as follows :
Given a liquid swarming with a mixture of various organisms,
of which it is estimated by microscopical inspection that one
individual in twenty is of the kind it is desired to cultivate;
dilute the liquid to such an extent that one drop of it should
contain but a single species : it is then probable that every
twentieth drop will contain a single isolated individual of the
desired organism. Fifty tubes, more or less, of sterilised nutrient
1 Jnl. Fed. Inst. Brewing, 1889, 3, 23.
MICROSCOPICAL AND BIOLOGICAL
355
material are prepared, and into each a single drop of the diluted
organism holding fluid is introduced.
One or possibly more of the tubes will thus be inoculated with
an isolated example of the desired organism, which will multiply
in the sterilised nutrient material and thus yield a pure cultiva-
tion which can be recognised by the microscope.
This, practically speaking, led to the initial stage of Hansen's
experiments, which were briefly yet excellently detailed by
Morris l as follows :
"A vigorous fermentation with the yeast from which it was
desired to cultivate is promoted in a Pasteur flask (fig. 105) ; the
yeast formed is then largely diluted with a
known volume of sterilised water, thoroughly
mixed with the water by shaking, and the
number of cells in a small drop of the water
counted. The counting is effected by means
of a haematimeter. This may consist either
of a microscopic cover-glass on which a
number of microscopic squares have been
ruled, or of a microscopic glass slide on
which the squares are ruled in the centre
of a very shallow cell. A good form of
the latter is made by C. Zeiss, of Jena, in
which the squares measure ^jy^th f a
square mm., and the cell is O'l mm. deep ;
the cubical capacity, therefore, of each
square, when the cover-glass is on, being '00025 mm. The drop
is placed well upon the squares, which then assist the eye in
counting the cells contained in the drop. Supposing ten cells are
found ; then, if a similar sized drop is added from the fluid, which
has again been thoroughly shaken, to a flask containing a known
volume of sterilised water, say, for instance, 20 c.c., the prob-
ability now is that this 20 c.c. of water contains ten cells. The
flask is thoroughly shaken for some time, and then 1 c.c. of the
liquid quickly introduced into each of twenty flasks containing
nutritive solution : there is now in all likelihood one cell in each of
ten of these twenty flasks. This is of course only a probability.
In order to be sure that some of the flasks contain only one cell,
it is necessary to allow them to remain until a growth appears.
Directly after adding the 1 c.c. of the diluted yeast to the flasks,
they are thoroughly shaken and placed in the incubator at the
required temperature, the cell or cells present then sink to the
1 Jnl. Soc. Chem. Ind., 1887, 113, 123.
FIG. 105.
356 THE BREWER'S ANALYST
bottom of the flask, remain and grow where they settle, which, in
the latter case i.e. if more than one cell is present is probably at
different points on the bottom. After some days the flasks are
carefully examined and the points of growth noted. In those
flasks in which there is only one speck of growing yeast visible,
the inference is that it proceeds from one cell, and consequently
the flask contains a pure cultivation ; in other cases it is possible
that two or more specks are visible ; then it is safe to conclude
that more than one cell was sown in the flask, and its contents
are consequently rejected.
This method has yielded good results in Hansen's hands,
especially with ferments which have some distinguishing
characters, such as Sacch. apiculatus. This method also gives
much better results than the one about to be described when it is
wished to separate weak and strong yeasts which are growing
together in a nutritive liquid. Another point in its favour is the
complete absence of any possibility of outside contamination after
the 1 c.c. of diluted yeast has been added to the flask.
Hansen, however, afterwards adopted a solid medium for such
cultivations, viz., hopped wort and gelatine; and he gives the
preference to this material, except under the circumstances
mentioned above, since it enables the experimenter to directly
observe the individual cells under the microscope, and to follow
the course of their development. He adopted a modification of
Koch's gelatine-plate method, taking, however, more elaborate
precautions to prevent contamination after the inoculated gelatine
is spread on the plate. In order to prepare a pure cultivation of
yeast, we take a growth of young and vigorous cells, dilute this
down very largely with sterilised distilled water in a small
Chamberland flask until the proper dilution is reached (this is
ascertained by a microscopic examination), and then again dilute
a drop of this with sterile, beer- wort gelatine (hopped wort of about
1058 sp. gr. with 5-10 per cent, gelatine), until we have an
extreme dilution. A drop of this is then withdrawn with a
sterilised glass rod, and spread upon the under side of a thin
cover-glass, which is then quickly placed on the ring of a Bottcher's
moist chamber. Fig. 106 represents one of the chambers in
question : a is the thin cover-glass, with a layer of gelatine on its
under surface b, and placed on the glass circle c, which is 30 mm.
in diameter and cemented to the glass slide ; d is a thin layer of
sterile distilled water. The inoculated gelatine having been
spread on the glass circle and allowed to set, the chamber is then
placed on the stage of the microscope and examined.
MICROSCOPICAL AND BIOLOGICAL 357
One or two well-isolated yeast cells are picked out, and the
position of these marked on the glass circle by a marker of some
description. The whole is then placed in an incubator at about
68 F. (20 C.) and allowed to remain for a day or two. At the
end of about two days the growths are generally visible to the
naked eye, and appear as small, whitish specks about the size of
pins' heads. These specks should be well separated from each
other on the glass circle. When the specks have attained a
sufficient size they are transferred to sterile hopped wort, of about
1'058 sp. gr., contained in Pasteur flasks. These consist of
flasks with the neck drawn out and bent over, as shown in the
figure, and with short side tubes, which are closed with a piece of
india-rubber tubing and a glass rod ; the bent tube is closed with
a plug of sterilised asbestos. The transference is effected by
quickly lifting the cover-glass, with the colonies, plunging a short
piece of sterilised platinum wire into the colony, and then
FIG. 106.
immediately dropping this into the side tube of the flask, the
glass-rod stopper being quickly withdrawn and replaced. Having
got the colony which we know is derived from one single cell into
the flask, we are then in a position to study its characters and
properties.
Such is the process which Hansen has employed to effect a
revolution in the study of the Saccharomycetes. By its means
he has succeeded in separating a number of apparently different
species of yeasts, from which he has selected six for further study.
In addition to these he has isolated two varieties of ordinary
bottom-fermentation yeast, which are at present used in the
brewery of Old Carlsberg, and also in a very great many other
breweries on the Continent. He has also determined that the
form, the limits of size, and the appearance of the cells do not
remain constant for each variety of species, but are influenced by
different conditions of growth. The form and phases of develop-
ment of the cells, however, when viewed from another standpoint,
give very important differences for each variety. This is the case
when the cells of the different varieties are exposed to similar
conditions, as in the ascospore and film formations : it is found
358 THE BREWER'S ANALYST
then that the different yeasts behave in a very different manner,
and each species gives well-defined characteristics. This can only
be explained by the supposition that the different varieties or
species have distinct, innate properties.
We will now proceed to consider the differences which Hansen
has found between the different varieties of yeast. He has, as
stated, differentiated six species of yeast, which he calls :
Saccharomyces cerevisias, I.
Saccharomyces Pastorianus, I., II., and III.
Saccharomyces ellipsoideus, I. and II.
The ordinary sedimentary forms of these are shown in Plates
XIV., XV., and XVI., figs. 107 to 112.
It will be seen that, although the varieties taken separately
appear quite distinct, yet if they were mixed it would be extremely
difficult to detect one from the other ; for instance, the S. Past.
when mixed with S. cerev., or the S. ellip. when mixed with S. Past.
or S. cerev. The size of the cells varies considerably with the
species.
The characteristic which Hansen chiefly relies upon in differen-
tiating these species is the ascospore formation. The formation of
ascospores in yeast cells has long been noticed, Reess, Engel, and
several other observers having described it, and attributed this
formation to various causes. Reess built up a system of the
Saccharomycetes based upon the form and size of the cells and
spores. Brefeld concluded that only "wild''' or "natural" yeast
was capable of giving spores, whilst cultivated yeast had lost this
property. Hansen J examined his six species for this formation as
follows : A small quantity of the yeast was spread on a sterilised
gypsum block ; this block was then placed in a flat-covered glass
dish and was kept moist by filling the latter half full of water.
The formation was then generally seen when the dish had stood
for a few days at the ordinary temperature. The spores generally
form as round bodies within the cell, and are usually accompanied
by the " sheath-wall " formation. Plates XVII., XVIII., and XIX.,
figs. 113 to 118, show the formation for the six species. Hansen
investigated the influence of different temperature upon the rate
of formation of the spores, in order to determine whether the
different species could be distinguished from each other in this
way. For this purpose it was necessary to know :
(1) The limits of temperature, i.e. the highest and lowest
temperatures at which spores were formed.
1 Meddelelser fro, Carlsberg Laboratories 1883.
Bailey's Brewer s Analyst.}
[PLATE XIV.
FIG. 107. Saccharomyces cerevisiae, I.
FIG. 108. Saccharomyces Pastorianus, I.
[To face p. 358.
Bailey's Brewer's Analyst.}
[PLATE XV.
FIG. 109. Saccharomyces Pastorianus, II.
FIG. 110. Saccharomyces Pastorianus, III.
[To face p. 358.
Bailey's Brevets Analyst. ]
[PLATE XVII.
FIG. 113. Spore Formation.
Saccharomyces cerevisise, I.
FIG. 114. Spore Formation.
Saccharomyces Pastorianus, I.
[To face p. 358.
Bailey's Brewer's Analyst.}
[PLATE XVIII.
FIG. 115. Spore Formation.
Saccharomyces Pastorianus, II.
FIG. 116. Spore Formation.
Saccliaromyces Pastorianus, III.
[To face p. 358.
MICROSCOPICAL AND BIOLOGICAL
359
(2) The most favourable temperature at which the spores were
formed.
(3) The ratio of the intermediate temperatures.
The results obtained (which are given in Table I.) showed that
the formation of spores proceeded very slowly at ordinary tempera-
tures, but more rapidly as the temperature rose, until it reached
a certain point. When this point was passed, then the formation
TABLE I. ASCOSPORE FORMATION.
Temperature.
S. cerev.
I.
S. Past.
I.
S. Past.
II.
S. Past.
III.
S. ellip.
S. ellip.
II.
r.
T,
99'5
96-8-98-6
37-5
36-37
None
29 hours
...
...
95
35
25
...
None
92-3
33-5
23
...
...
M
None
31 hours
88'7
31-5
None
36 hours
23
86
30
20 hours
30 hours
...
tj
...
84-2
29
27
None
None
23 hours
22 hours
81-5
27-5
24 ,,
34 hours
35 hours
797
26-5
f>
30 .
...
77
25
23 hours
...
25- hours
28
21 hours
27 hours
73-4
23
27
26 hours
27 V,
71-6
22
...
...
29 hours
64-4
18
50 hours
25 hours
36 hours
44 ,,
33 hours
42 hours
617
16-5
65 ,,
...
53
59
15
...
50 hours
48 hours
45 hours
...
51-9-53-6
11-12
10 days
...
77
...
5 '5 days
50
10
89 hours
7 days
4 "5 days
47-3
8-5
None
5 days
9
9 days
44-6
7
7
7 days
11 days
37-4-39-2
3-4
...
14
17
None
None
None
32-9
0-5
...
None
None
...
...
again decreased, until it at last ceased entirely. The lowest
temperature found for the six species was 23-26"6 F. (J-3
C.); the highest 99'7 F. (37'5 C.). The highest and lowest
temperatures for the different species were also different, and also
the limits of temperature within which the ascospore formation
takes place in the different species. We see from the table that
the differences at the high temperatures, and down to 77 F.
(25 C.), are almost inappreciable; but when we lower the
temperature the differences become more marked. For instance,
at about 51 '8 F. (11 C.), S. cerev. first shows ascospores at the
end of ten days, whilst S. Past. II. shows them at the end of
seventy-seven hours, and so on with the other species. In making
360 THE BREWER'S ANALYST
this comparison, it is necessary to make the experiments with
each of the six species under exactly the same conditions, since the
use of old or young cells, composition of the nutritive medium, etc.,
exercise a marked influence on the temperature and rate of
formation of the ascospores. Upon these results Holm and
Poulsen 1 have based a method for the practical analysis of
brewing yeast. Hansen found that the ordinary bottom-fermenta-
tion yeast only formed spores at 77 F. (25 C.) after some days,
whilst, as we have seen, the " wild " forms, as exemplified by the
six species we are considering, form ascospores at this temperature
in a few hours. Working with pure cultivations of each species,
Holm and Poulsen found that they were able to detect 0'5 per
cent, of S. Past. I. and III., or S. ellip. II., in a mixed yeast ; and,
as Hansen has shown, that when these "wild" yeast forms,
which are the cause of the diseases in bottom-fermentation beer,
are present in a barm to the extent of not more than 2 '5 per
cent, of the total yeast, they do not develop their particular form
of disease ; it will be seen that, for bottom yeast at least, the
ascospore formation forms a valuable means of determining the
purity of a barm.
The next and most recent of Hansen's observations are those
of the *' film " formation. 2 The formation of films on the surface
of the culture liquid is peculiar to most micro-organisms when
the greater portion of the food material contained in the liquid is
consumed. As the result of a series of exhaustive experiments
with the six foregoing species, Hansen has established differences
in their film formation, both as regards the limits of temperature
within which it is possible for a growth to take place, and also in
the appearance of the cells of the film ; whilst, as a general rule,
all the cells of old films show a remarkable change of form, large
mycelium-like cells in ramified colonies being formed, yet the
cells of S. cerev. L, S. Past. II., and S. ellip. II., in a young state,
show no mycelium-like colonies. S. Past. I. and HI., and S. ellip.
L, however, show them very early. Table II. shows the tempera-
tures and the length of time necessary for the formation of the
films of each of the six species. At the high temperatures there
is very little difference in the forms, excepting in the case of
S. cerev. I. and S. ellip. II. \ but the young films at lower
temperatures, 55'4-59 F. (13-15 C.), show very marked differ-
ences, and allow the various species to be easily distinguished.
S. Past. II. and S. Past. III., which are both top-fermentation
1 Meddelelser fra Carlsberg Laboratoriet, 1886.
2 Ibid.
MICROSCOPICAL AND BIOLOGICAL
361
forms, and the cells of which are very similar under ordinary
conditions, show a marked difference at this temperature. Plates
XX., XXL, and XXII., figs. 119 to 124, show the various forms
of the cells of the films of the six species at 55'4-59 F.
(13-15 C.).
These are the principal scientific results obtained by Hansen
in his researches on the morphology and physiology of pure-
cultivation yeasts. It is an open question how far these different
yeasts can be considered to represent distinct species, since it is
at present a moot point where the bounds can be drawn between
TABLE II. FILM FORMATION.
Temperature.
S. cerev.
S. Past.
S. Past.
S. Past.
S. ellip.
S. ellip.
F.
c.
I.
I.
II.
III.
I.
II.
104
96-8-100-4
40
36-38
None
None
None
8-12 days
91-4-93-2
33-34
9-18 days
None
None
None
8-12 days
3-4
78-8-82-4
26-28
7-11
7-10 days
7-10 days
7-10 days
9-16
4-5
68-71-6
20-22
7-10
8-15
8-15
9-12
10-17
4-6
55-4-59
42-8-44-6
13-15
6-7
15-30
2-3 months
15-30
1-2 months
10-25
1-2 months
10-20
1-2 months
15-30
2-3 months
8-10
1-2 months
37-4-41
3-5
None.
5-6
5-6
5-6
None
5-6 ,,
35-6-37-4
2-3
None
None
None
None
species and varieties in the Saccharomycetes. On this account
Hansen has preferred to give his yeasts the above distinguishing
numerals instead of renaming them, leaving this latter until
more is known on the subject.
Jorgensen, in his book on Die Microorganismen der Gdrungs-
industrie, attempts to classify the Saccharomyces and sums up
Hansen's six species as follows :
SaCCharomyces eereviSSe, I. A top-fermentation yeast,
giving excellent results in practice ; used in the breweries of
London and Edinburgh in an impure state ; develops ascospores
at temperatures between 51'8-9S-6 F. (H-37 C.) ; film forma-
tion at 55'4-59 F. (13-15 C.) ; the predominant number of
the cells resemble the original yeast.
Saceharomyces Pastorianus, I. Gives a bitter flavour to
beer; develops ascospores at temperatures between 37-4-86'9 F.
(3 and 30'5 C.) ; film formation at 55'4-59 F. (13-15 C.);
fairly numerous, strongly developed, mycelium-like colonies of
very elongated, sausage-shaped cells.
SaCCharomyces Pastorianus, II. Causes no disease in
beer; develops ascospores at temperatures between 37'4-22'4 F.
362 THE BREWER'S ANALYST
(3 and 28 C.); film formation at 55'4-59 F. (13-15 C.);
oval and round cells predominant.
Saeeharomyees Pastorianus, III. Cause of yeast- turbidity
in beer; develops ascospores at temperatures between 47'3-82'4
F. (8-5 and 28 C.) ; film formation at 55'4-59 F. (13-15
C.) ; strongly developed colonies of sausage- or thread-shaped,
mycelium-like cells.
Saeeharomyees ellipsoideus, I. Yeast of grapes ; develops
ascospores at temperatures between 45 1 5-88 < 7 F. (7 '5 and
31-5 C.); film formation at 55*4 -59 F. (13-15 C.) ; greatly
ramified and strongly developed colonies of short and long cells ;
ramifications often forked.
Saeeharomyees ellipsoideus, IT. Cause of yeast-turbidity
in beer ; develops ascospores at temperatures between 46'4-93'2
F. (8 and 34 C.); film formation at 5.5-4-59 F. (13-15 C.);
resembles the ordinary form in a marked degree.
In addition to these, various other yeast forms have been
described by various observers, viz., S. exiguus (Reess), S. minor
(Engel), S. conglomerate (Reess), and so on, but they have not
yet been put to the test of pure cultivation. There is another
yeast form, already alluded to, viz., Saeeharomyees apiculatus,
which possesses great interest on account of its being the only
alcoholic ferment whose cycle in nature has been exactly deter-
mined, and since it formed, as already stated, the starting-point
in Hansen's researches on the yeasts. It lends itself especially
to this purpose, since it has a peculiar shape which is possessed
by no other yeast. It forms typical, citron-shaped cells which
do not yield endogenous spores, and therefore, correctly speaking,
it does not belong to the genus Saeeharomyees. The ferment
is found upon all ripe, succulent fruit, in the yeast of wine, and
also in the spontaneously fermented Belgian beer. S. apieulatm
is a bottom ferment which is capable of setting up alcoholic
fermentation in beer. The fermentation is, however, slight, only
1 per cent, of alcohol being formed instead of 6 per cent,
formed by S. cerevisx under similar conditions. The explana-
tion of this is, that it does not ferment maltose, and does not
secrete any invertase. In dextrose solutions it sets up a vigorous
alcoholic fermentation. Microscopical examinations of ripe,
succulent fruit in summer show that this ferment is present in
considerable quantity in a healthy, budding condition ; on the
unripe fruit, leaves, etc., it is not found, and no trace of the
ferment can be found upon the plants in the winter. Hansen
has, however, shown that the ferment hibernates in the earth
Bailey's Brewer's Analyst.]
[PLATE XX.
FIG. 119. Film Formation.
Saccharomyces cerevisise, I.
FIG. 120. Film Formation.
Saccharomyces Pastorianus, I.
[To face p. 362.
Bailey's Brewer's Analyst.'}
[PLATE XXL
FIG. 121. Film Formation.
Saccharomyces Pastorianus, II.
FIG. 122. Film Formation.
Saccharomyces Pastorianus, III.
[To face p. 362.
MICROSCOPICAL AND BIOLOGICAL 363
under the trees, and in early summer is carried again into the
air, and on to the ripe fruit by the action of the wind and insects.
Now, what have been the practical results of this work of
Hansen? Mention has already been made of the fact that pure-
cultivation yeast is in use at the Carlsberg breweries. In 1883
Hansen, having had occasion to study the causes of some cases of
yeast-turbidity, came to the conclusion that the only real remedy
for diseases of beer caused by " wild " yeast was to work in all
cases with yeast which could be guaranteed free from these wild
forms. This can only be done by Hansen's method of pure
cultivation, or some modification of this method.
Hansen l succeeded in isolating from the beer which was sub-
mitted to him, by the method described, three varieties of yeast
S. ceremsx (ordinary bottom yeast, which constituted the
greater portion), S. Pat. III. (a form of bottom yeast), and the
S. ellip. II. (a form of top yeast).
Experiments carried out with the pure yeasts showed that
fermentations with the /S'. cerev. gave a beer which was quite free
from any form of disease, but that when either one or both of
the other forms were also used in the proper proportions, the
disease was set up. Further experiments showed that the yeast-
turbidity was not caused if the two " wild " yeasts were not
added until the end of the primary fermentation. Also, that
the disease did not show itself if S. Past. III. or S. ellip. II.
formed 2 '5 per cent, only of the yeast used for pitching, and
the fermentation carried on in the fermenting cellar until the
beer showed an attenuation of 6 '7 Balling, and the resulting
beer stored for at least three months. If, however, the attenua-
tion was not run down so low as this, and the storage not con-
tinued so long, the disease showed itself with the above proportion
of "wild "yeast.
The result of these experiments was that Hansen cultivated
two varieties of bottom S. cerev. for use in the Old Carlsberg
brewery, which are known as Nos. 1 and 2. These yeasts, which
under the microscope appear to the uninitiated to be identical,
give very different results in practice.
No. 1 gives a beer well adapted for bottling, and containing
less C0 than No. 2. The beer should remain bright in bottle
for at least three weeks ; it has also a lower attenuation than No.
2. This yeast is chiefly employed for home use.
No. 2 gives a good draught beer, containing more C0 2 than
No. 1 ; it is not adapted for bottling, and is much preferred by
1 Zeitschrift f. das gesammte Brauivesen, 1883, 477.
364 THE BREWER'S ANALYST
German brewers to No. 1, and is therefore chiefly cultivated for
export.
Now, a word as to the cultivation of pure yeast upon a sufficient
scale to barm brewery vessels. It has been shown that it is
comparatively easy, with experience and a rigid adherence to the
small precautionary details, to obtain a small quantity of pure
yeast, but the question arises How are we to carry on the
cultivation under conditions of purity until we have sufficient
pure yeast for our fermenting square 1 Well, it is done by trans-
ferring the yeast from a small flask to a number of larger flasks,
and when the growth of yeast is over, dividing the yeast in these
between a still greater number of larger flasks ; taking care, of
course, to use all due precautions, as many as fifty or more 1 J
litre Pasteur flasks being used for the last laboratory cultivation.
This, however, only gives about 2 Ibs. of fairly thick yeast. It is
then necessary to work with still larger vessels : this is done in
the brewery, and as, fortunately for the Danish brewers, they
are not hampered by any excise regulations in the breweries, they
are able to arrange small fermenting rounds in such a way that
they can collect in them sterilised wort, and after adding the
yeast, lock the vessels up and adopt means to prevent aerial
contamination.
The employment of these pure yeasts is coming very largely
into use in the beer-drinking countries of the Continent, and
some of the most noted brewing technologists have given it their
support, notably, Jacobsen, Aubry, Marz, Lintner, etc. The
latter sums up the question in the following statements :
"1. By contamination with so-called 'wild' yeasts, an other-
wise normal brewery yeast can be rendered incapable of producing
a beer of good flavour and with good keeping properties.
" 2. A contamination with ' wild ' yeasts may be produced by
the dust of the air during summer and autumn, by the malt, or
other sources.
" 3. By employing Hansen's method of pure cultivation and
analysis, it is possible to obtain from a contaminated yeast a good
brewery yeast in a state of purity.
" 4. Yeast cultivated in a state of purity possesses in a marked
degree the properties of the original yeast before contamination,
as far as concerns the degree of attenuation, the flavour, and
keeping properties of the beer.
" 5. There exist different varieties of normal bottom yeasts
(S. cerev), each with special properties, which, like the peculiarities
of species, are maintained constant.
MICROSCOPICAL AND BIOLOGICAL 365
"Sufficient has already been done to prove that in ordinary
brewery yeast we also possess a mixture from which, by Hansen's
method, several varieties of S. cerev. can be separated, which
cannot microscopically be distinguished from each other, but
which, when used upon a practical scale, give entirely different
results, both as to flavour, brightening, attenuation, and mode of
separation of the yeast.
"Experiments have also shown that these characteristics can be
maintained unimpaired throughout a very great many successive
fermentations in the brewery."
Having thus far paved the way by showing the rapid strides
that have been made, we have now to give a few details as to
the general apparatus employed and the precautions taken during
manipulation, and follow with details of the usual biological
methods.
It is hardly necessary, from what has gone before, to state that
in all biological examinations it is absolutely necessary that all
vessels and apparatus flasks, test-tubes, beakers, filter papers,
cotton wool, glass rods, etc., to be used must be thoroughly
sterilised by heating to at least 248-302 F. (120-150 C.), that
is, at a temperature which is sufficient to kill all micro-organisms
and their spores, which may have settled from the air upon and
within the vessels, etc. In the case of large vessels such as flasks,
this is conveniently done by passing the flame of a Bunsen burner
over the surface of the vessel until it is hot, and then immedi-
ately closing the mouth and side tube with sterilised cotton wool
and india-rubber tubing and glass rod.
For small vessels, test-tubes, beakers, cultivation chambers, etc.,
an air-bath, heated to the required temperature, is most convenient.
This should be maintained at 248-302 F. (120-150 C.), and
the vessels allowed to remain in it for two to three hours at that
temperature. The cotton wool for plugging the mouths of flasks
and test-tubes must also be well sterilised by being loosely pulled
out and then heated in the air-bath to the above temperature for
some hours on several successive days. Filter-papers used for
covering the cotton-wool plugs should also be heated in the
air-bath.
Forceps, pipettes, and all other odds and ends of apparatus
must be sterilised by being passed through a Bunsen flame at the
moment of use.
The solutions most commonly employed for cultivations are
rendered sterile and ready for inoculation in the test-tubes and
small flasks in the following way : The solid material, as broth-
366
THE BE EWER'S ANALYST
gelatine, beer- wort gelatine, etc., must be poured into the
previously sterilised flasks and test-tubes, whilst still in a fluid
state, and then sterilised by being boiled twice or three times on
successive days. Tyndall has pointed out that the spores of
certain bacteria are not killed by boiling, therefore it is necessary
to boil on successive days in order to give the unkilled spores an
opportunity of developing between each successive boiling, when,
of course, the next boiling kills the developed organism.
No test-tube or flask containing nutritive material can be con-
sidered sterile until it has been kept at a temperature of 89 '6-
100-4 F. (32-38 C.) for at least
seven days without any sign of
growth appearing. An excellent
form of steam steriliser is Petrie's,
which enables flasks, tubes, etc., to
be sterilised in a current of steam
at a pressure of one atmosphere. It
consists of a cylinder of steel plate
coated with lead, with door fitting
air-tight, and covered with felt to
prevent radiation. The shelves are
of tinned iron and the supporting
tables of wood. It possesses a series
of Bunsen burners and a steam
generator.
Fig. 125 shows an autoclave or
kih pressure steam digester which
may be employed for sterilising as
well as numerous other purposes.
It possesses a copper boiler, bridge
clamp, and central screw, cover of
phosphor bronze, safety-valve, steam stop-cock, and manometer.
The outer cover is of sheet iron.
Sterilisation is effected by the agency of steam under pressure,
in which condition it possesses a higher temperature than when
existing at the ordinary atmospheric pressure. Water is placed
in the bottom of the vessel to a depth of a few inches, the shelf-
holder with its articles introduced, the lid screwed down, and heat
applied from below by means of a large Bunsen burner.
Since water always boils at a certain temperature for a par-
ticular pressure, the heat of the interior is ascertained from the
indications of the pressure gauge. The autoclave is a very useful
form of apparatus when samples of beer are to be sterilised. If
FIG. 125.
MICROSCOPICAL AND BIOLOGICAL
367
such samples are heated in the ordinary steam steriliser, a loss of
alcohol takes place. By conducting the operation in an autoclave,
and using beer of the same alcoholic strength as the samples, freed
from carbon-dioxide in order to prevent frothing, instead of water
for charging the apparatus, such samples may be sterilised without
loss of alcohol.
For the majority of purposes, however, tubes, flasks, etc., may
be conveniently sterilised by washing them first with concentrated
FIG. 126.
sulphuric acid, afterwards with distilled water, plugging them
with cotton wool, and placing in the ordinary air-bath, heating
intermittently to 248-302 F. (120-150 C) for from two to
three hours.
Apart from the ordinary forcing tray which is well known as
large copper tray about 4 inches in depth, containing water,
placed in a cupboard free from draughts and the water maintained
at a constant temperature of 75-80 F. (23-8-26-6 C.) by means
of a thermostat the more compact Hearson's incubating apparatus
(fig. 126) may be conveniently employed.
368 THE BREWER'S ANALYST
This consists of a vessel of sheet metal such as copper, having
double walls, and provided with a glass door protected by an
outer wooden one; the space between the walls is filled with
water. The outer case and stand are of pine, and a patent gas
regulator is employed so that the interior of the apparatus may
be kept at the required temperature.
It will be as well to point out the necessity of having some
place set apart entirely for pure-cultivation work, as the success
or failure of these operations depends greatly upon the freedom
of the air from germs at the time the experiments are being
carried out. For this reason the room should be allowed to
remain perfectly undisturbed for some hours before the culti-
vation is made, in order to allow the atmospheric dust to settle.
The foregoing precautions being observed, we may proceed
with typical examples of biological work usually carried out by
the brewer's analyst.
BIOLOGICAL METHODS. AERIAL CONTAMINATION. SURVEY
OF BREWERY AND MALTING PREMISES.
The analyst from time to time throughout each year should
make a biological survey of the brewery premises in order to
detect any undue infection.
To do this, a number of flasks are prepared containing
sterilised wort or meat gelatine. The flasks, usually of wide
mouth, are thoroughly cleansed, labelled, and the superficial area
of the mouth ascertained and noted on the label. They are
then sterilised and the nutritive solution added, after which
they are plugged with cotton wool and again sterilised. Upon
removal from the sterilising apparatus, each flask is held under
a stream of cold water and turned and twisted about until the
gelatine is spread over the surface in a thin film and has become
solidified. Caps of sterilised paper are now tied over the plugs,
and the flasks are taken to the yeast store-room, fermenting-room,
cooler, refrigerator, malt-house, or other locality where the
observation is to be made. The caps and plugs are here removed,
the plugs being placed temporarily inside the caps, and the flasks
left standing in the open for one hour. The plugs and caps are
then replaced, the particulars concerning each flask written on
the label, and the flasks taken back to the laboratory so that the
germs which have fallen into them may be cultivated by incu-
bation. The latter is performed by placing the flasks in the
incubator and maintaining them for two or three days at a
MICROSCOPICAL AND BIOLOGICAL 369
constant temperature of 68 F. (20 C.), by which time the
organisms will have fed upon the nutritive material contained in
the flasks and have formed colonies in the form of white or
coloured specks on various parts of the solidified gelatine. These
are now counted ; and by taking into account the area of the
mouth of each flask and the number of colonies formed, a simple
calculation gives the number of germs falling per square inch or
per square foot, eta, from the air in the locality where the flasks
were opened. On the other hand, the individuals comprising the
colonies can be taken up by a piece of platinum wire and either
cultivated and their action on wort, beer, etc., noted, or they
may be directly examined microscopically.
BIOLOGICAL EXAMINATION OF WATER.
Koch's Method. For this purpose Koch's "plate culture"
method is conveniently employed. Plates of ordinary glass are
used, of such a size as can be easily examined under the micro-
scope, their breadth being deter-
mined by the distance between the
centre of the objective and the
pillar which supports the body of
the microscope, and they may be
about twice as long as they are
wide. A convenient size, however,
is 3 x 5 inches. The plates are F IG i 2 7.
first thoroughly sterilised. An
apparatus devised by Koch is now used for spreading the mixture
and water and nutritive gelatine on the glass plates. This
apparatus is shown (fig. 127). It consists of a wooden tripod-
stand, the feet of which are formed of three screws by means of
which the apparatus can be accurately levelled. The shallow
glass tray, shown on the top of the glass plate, is filled with
water and ice and placed on the tripod-stand. This is covered
with the glass plate on which the culture plate is to rest ; and
on this the bell glass for covering the cultivation plate and
protecting it.
In using the apparatus, the glass plate which is to receive
10 c.c. of meat gelatine is taken out of the steriliser and reversed
on to the glass plate on the top of the inner dish under the bell-
shaped cover. After melting the gelatine, which should be done
without going to a higher temperature than 95 F. (35 C.), the
plug of the test-tube is removed and 1 c.c. of the water, after
24
370 THE BE EWER'S ANALYST
thoroughly shaking, introduced by means of a sterilised pipette,
avoiding as far as possible a vertical position of the tube.
The bell-shaped cover on the levelling apparatus is now raised
just enough to allow the mixture to be spread on the glass plate,
where it sets in about a minute. As the area has to be measured
if the colonies are too numerous to be counted all over, the
gelatine should be spread in the form of a rectangle.
As soon as the gelatine has set on the plate, it is at once
removed in its dish from the levelling table and placed in the
incubator and maintained at a constant temperature of 68 F.
(20 C.). The period of incubation generally varies from three to
five days, but sometimes it is continued for a longer period of time
to make sure that all the organisms present have had a due
opportunity of developing.
The gelatine plates are daily inspected during the period of incu-
bation, without removing the glass-cover, so that the progress of
the colonies derived from the individual organisms, may be
watched. They will differ considerably in appearance : some will
appear as white, slimy-looking spots resting
on the surface of the gelatine, others will
have spread more considerably amongst the
surrounding gelatine ; some may have an
FIG. 128. iridescent appearance, others may be bril-
liantly coloured.
Many of the colonies will be found to have left the gelatine
film intact, others to have liquefied it, and various degrees of
liquefaction may be observed amongst the different colonies.
When, however, they have reached fair dimensions, and before the
contours of different colonies have begun to coalesce, the plates
should be withdrawn for examination.
The Moist Chamber. Instead of adopting Koch's apparatus
as previously described, that known as the moist chamber method
may be employed.
This consists of two glass dishes as shown (fig. 128). The lower
dish has a diameter of about 8 inches and a depth of about 4
inches. The outer dish is slightly wider, and is used as the cover.
The dishes are first thoroughly cleansed and then sterilised in a
metal box as shown (fig. 129). They are then smeared internally
with glycerine, which, as first shown by Tyndall, retains any
bacteria which falls upon them. A layer of filter paper, moistened
with thirty or forty drops of a saturated solution of mercuric
chloride (a powerful germicide), is placed in the bottom of the
narrower dish.
MICROSCOPICAL AND BIOLOGICAL
371
The water contained in this solution keeps the air in the
apparatus saturated with moisture. A stand which will hold
several cultivation plates, and which may also be used for the
before mentioned Koch's method, may be here employed, so that
several cultivations may be simultaneously carried on. It consists
FIG. 130.
FIG. 129.
of glass plates as shown (fig. 130). When a number of these are
superimposed, they form shelves on which the cultivation plates
can be placed. The moist chamber containing the cultivation
plates is then placed in the incubator.
Counting" the Colonies. For this purpose the apparatus
invented by Wolfhiigel (fig. 131) is generally employed, which
consists of a wooden base, surmounted by a blackened ground
FIG. 131.
glass plate, on which the cultivation plate, withdrawn from the
incubator, is placed, and over this is a glass plate marked into
squares with a diamond. This plate is supported at the corners
in a manner which allows the cultivation plate to be introduced
or withdrawn without the gelatine film coming in contact with it.
The sides of the squares on the counting plate'are a centimetre
(| inch) long, and several of these squares are further subdivided.
The counting is performed with the assistance of a magnifying
372 THE BREWER'S ANALYST
glass ; the number of colonies in a certain number of squares
being counted, and the average contained in each square thus
estimated. The number so found, multiplied by the number of
squares which are equal to the size of the gelatine film, gives the
number of germs contained in the quantity of water used for
infecting the gelatine.
Petri Dish Method. This is a much more simple method
than the plate-cultivation methods previously described. It con-
sists in taking two Petri dishes similar to those shown (fig. 128),
but considerably smaller, one of which fits over the other.
The dishes are usually about 4 inches in diameter and half
an inch in height. They are thoroughly cleansed and sterilised,
and then the warm, infected wort or meat gelatine is run into the
lower dish and spread over the bottom in a thin layer ; the upper
dish, which forms the cover, being immediately placed on after
adding the nutrient, and the whole then left until the gelatine
solidifies. The dishes are then removed to the incubator, and
when the colonies are formed they can be examined under the
microscope and preparations made from them just as when a
cultivation plate is employed.
In order to count the colonies, the dish is placed on a sheet of
black paper ruled in squares with Chinese white.
Hansen's Method. Hansen has shown that many organisms
found in water which are capable of developing on a gelatine-wort
plate will not grow in wort or beer, and that the vast amount of
organisms found in water have no significance whatever for the
brewer, as very few are capable of vegetating in either wort or
beer.
His method consists in taking fifty Pasteur flasks, each having
a capacity of about 20 c.c. These are divided into Groups I. and
II. Into each of the twenty-five flasks of Group I., 10 c.c. of
wort are introduced ; and into the remaining twenty-five which
constitute Group II , the same quantity of beer. All the flasks
are then plugged with cotton wool and sterilised.
When the contents have cooled, one measured drop (0 - 004 c.c.)
of the water under examination is added to each of fifteen of the
flasks belonging to Group I., and also to fifteen of the flasks of
Group II.
To each of the remaining ten flasks of each group 0'25 c.c. of
the water is added. All the flasks are then agitated, so as to
distribute the organisms, and are then incubated for fourteen
days. At the end of this time the flasks are examined for
turbidity, and those which exhibit this sign of infection counted.
MICROSCOPICAL AND BIOLOGICAL 373
Taking the total quantity of water added to the ten flasks, the
number of flasks infected, and the total number of flasks taken,
we estimate the number of organisms presumably present in this
quantity of water, and from this is calculated the number present
in each cubic centimetre of the water. Thus if five out of ten
wort flasks (Group I.), to which 0*25 c.c. of the water had been
added, have become turbid, then, as the total amount of water
added to these ten flasks was 0*25 x 10 2'5 c.c., this quantity
presumably contains five organisms capable of development in
wort; consequently, the water contains two such organisms per
cubic centimetre. If, as sometimes happens, the whole of these
ten flasks have become turbid, no conclusion can be formed from
them. We then turn to the remaining fifteen flasks of each
group, to each of which only O04 c.c. of water had been added,
and apply the same method of calculation. The same process of
calculation is applied to the flasks in Group II., and the number
of organisms per cubic centimetre of water capable of developing
in beer similarly estimated.
BIOLOGICAL EXAMINATION OF MALT.
This test was formerly much in vogue, but of late years has
been more or less discarded ; still it is extremely useful, and gives
a good idea of the stability of a wort and the character of the
beer that may be expected from it. It is a test, however, that
is only reliable in the hands of one who has had considerable
experience of the manipulation of malts containing varying
percentages of caramelised grain, and kilned off at varying
temperatures.
In order to perform the test, a test-tube of about 300 c.c.
capacity is taken, a hole is knocked out of the bottom, and the
tube is then rotated over a Bunsen flame so as to permanently
round off the hole according to requirements. The hole of this
tube is now plugged with a piece of cotton wool and the tube
then placed inside a similar but slightly larger tube. A circle of
cotton wool is now plugged at the mouth, between the inner and
outer tube, 250 c.c. of distilled water are added to the inner tube,
and this is then plugged at the mouth with cotton wool. The
tubes are now placed in the sterilising apparatus and sterilised,
after which they are removed, and the contents cooled down
under a stream of tap-water. The tubes are then placed in the
water bath and allowed to remain until the 250 c.c. of water have
risen to the temperature at which the water in the bath is
374 THE BREWER'S ANALYST
maintained, viz., 150 F. (65'5 C.). Of the malt to be examined,
25 grams are now weighed and ground, the plug of cotton wool is
removed from the mouth of the tube and the ground malt added,
after which the cotton-wool plug is immediately replaced. The
tubes are again placed in the water bath and allowed to remain,
with occasional shaking, for 1 hour ; they are then removed and
cooled.
We have now a miniature mash, and by slowly raising the
inner tube (keeping the circle of cotton wool in its place) the wort
niters through the plug of cotton wool in the hole at the bottom
of the inner tube and is collected in the outer tube.
When the whole of the wort has filtered through, the inner
tube is quickly withdrawn, and the outer one then plugged with
cotton wool.
By these means we practically get a 10 per cent, wort in one
tube and the grains from the same in the other, the manipulation
having been accomplished under strictly biological conditions.
The tubes are now removed to the incubator and inspected at
the end of 12, 24, 36, 48, and 60 hours.
According to the number of malt samples it is intended to
test, so a number of tubes, prepared as described, are required.
Each tube is labelled and particulars noted thereon.
The following is a typical result of such examination :
BIOLOGICAL TEST.
Condition of Miniature Mash after
24 hours.
36 hours.
48 hours.
60 hours.
Sound.
Sound.
Cloudy.
Putrid.
Worts taken from the mash-tun taps may be examined by
incubating in sterilised test-tubes, and their keeping qualities
similarly noted.
BIOLOGICAL EXAMINATION OF HOPS.
This is generally performed by taking 2 grams of an average
sample of the hops, together with 100 c.c. of distilled water, in a
tube prepared as in the biological examination of malt just
described, incubating the same, and noting the colour, flavour,
and biological aspect of the liquor at the end of three days.
MICROSCOPICAL AND BIOLOGICAL 375
A plate-cultivation of the infusion may be made, as already
described, under water, and the incubated colonies counted and
microscopically examined. Naturally, any mould there may be
in hops is destroyed during" the boiling of the copper wort ; but in
purchasing hops the presence of mould is decidedly objectionable,
since, apart from its tendency to communicate nauseous flavours
to the wort, such hops have been badly grown, packed, or
stored.
A further method is to employ wort in the tubes instead of water.
In such instances it is advisable, for purposes of comparison, to
always reduce the wort to a gravity of 1050. One hundred
c.c. of the wort are added to the tube and sterilised, the contents
then cooled, and 2 grams of the hops added, the plug of cotton
wool being removed for the purpose and immediately afterwards
replaced. The tube is then placed in the incubator, and at the
end of four days the smell is carefully noted, the attenuation of
the wort determined, and after shaking and straining off the hops,
the sediment is microscopically examined.
BIOLOGICAL EXAMINATION OF YEAST.
From what has gone before it is obvious that, from a micro-
scopical examination of yeast, we are enabled to detect the
presence or absence of bacteria and the several species of the same;
and obviously the presence of more than two bacterial germs in a
field of 100 cells, that is to say, more than 2 per cent., is objection-
able, showing that greater care should be exercised in the cleans-
ing of the brewery plant and the exclusion of contaminated air.
In like manner we are enabled to detect the presence of mould,
the appearance of which should be sufficient to at once condemn
the sample for pitching purposes.
We are also enabled, by microscopic examination, to detect
whether the outline of the cells is thin and the yeast in con-
sequence young and vigorous, or whether it is thick and therefore
old, or whether there are granulated cells showing signs of
exhaustion by reason of being speckled. The general appear-
ance of the cells, clearness or transparency, boldness, method
of clinging together, number in bud, aspect of vacuole, etc.,
are all well-known signs in estimating the condition of the
sample.
Again, we are enabled to detect the presence or absence of any
undue proportion of amorphous matter, which, if present, points in
many cases to imperfect hop-back filtration of the wort or the
376 THE BKEWER'S ANALYST
retention of too much of the amorphous matter, which is thrown
up during the early stages of fermentation, and in most cases
removed and run to waste rather than that it should become inter-
mingled with the outcrops to be used for pitching. We are also
enabled, by microscopic examination, in conjunction with the use
of staining agents such as indigo, to detect the presence and
number of dead cells, more than 2 per cent, being decidedly bad,
and also by the use of iodine to detect the presence of starch, the
latter being important where flour and salt " dressings " are
employed.
These are the only points, however, which the microscope can
tell. We are not enabled by its use to detect with certainty the
presence or absence of " wild " yeasts, and, as we know from the
brilliant researches of Hansen that many yeasts communicate
objectionable flavours to beer, it becomes important, particularly
where brewing results are not brilliant or are in any way out of
the normal, that a complete examination of the pitching yeast be
made, and this naturally necessitates a biological examination.
We have already seen from Hansen's experiments that spore
formation and film formation are necessary in this respect, and
therefore it becomes essential to isolate the cells of our pitching
yeast, cultivate the same in sterilised wort, and also compel them
to live under conditions which form spores and films. From the
indications thus obtained we are then in a position to state with
certainty the different species which compose our stock, and
whether our troubles are attributable or not to the presence of
one or more species of wild yeasts.
BIOLOGICAL EXAMINATION OF BEER.
The application of this examination, generally known as the
"forcing tray" test, devised by Horace Brown, is of extreme
value to brewers, particularly where an export trade is done, since
by its adoption information is obtained as to the stability of beers
and whether they will remain bright and in condition under
adverse circumstances such as they are expected to be subjected
to during their voyage to foreign climes. We are thus able to
discriminate as to which beer out of a number of brewings is
best able to withstand the necessary adverse conditions ; and in
like manner with home trade, we are able to judge which beer
will stand the longest storage, is best for bottling, and which, on
the contrary, it is best to send out without delay.
The beers about to be examined should be carefully drawn from
MICROSCOPICAL AND BIOLOGICAL 377
casks, 1 through freshly bored peg-holes, into capacious Pasteur
flasks which have been previously sterilised and plugged. From
these flasks samples are then drawn into Pasteur flasks of small
size, also previously sterilised and plugged, and placed on the
forcing tray and maintained at a temperature of 75-85 F. (23'8-
29-4 C.).
At the time of placing samples on the forcing tray the specific
gravity of the remaining portions of the samples, after filling the
small Pasteur flasks, are tested, and also the acidity. A note is
made as to the condition of the samples, namely, their brightness,
flavour, etc. The samples are left on the forcing tray at the
forcing temperature for a period, as follows :
Stock pale ales 3 weeks.
Running beers 10 days.
At the end of these respective periods the beers are removed
from the tray and the following observations made and noted :
Flavour.
Degree of brightness.
Specific gravity.
Acidity.
Amount of deposit.
Microscopical examination of deposit.
The following is a copy of note-book, with examples, which will
be found useful in recording results :
1 It is not unusual to take samples from the racking tanks at the time of
filling the casks, but it should be remembered that the results of the forcing
of such beers are not as reliable as with samples drawn direct from shipment
casks, since in the latter case the beers will have been dry-hopped, the resins
acting to a large extent as a preservative, and that the interior of trade casks,
although no doubt scrupulously clean, are not sterile. On the whole, more
reliable results are therefore obtained by dealing with the beers direct from
the casks in which it is intended to send them out. It is also sometimes
advisable to force beers after the addition of salicylic acid, so as to gain an
idea of their keeping qualities under the influence of this antiseptic.
378
THE BREWER'S ANALYST
K
a
b
o
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J>OH
H
6
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t t
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S c &
<! Q
Is
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i-
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f
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I
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X
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gs
w
t
JD
O
CO
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co
* .-I CO (M CO t- !>
CO rH <M
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01^ TOOO>A^-rH -OiCvl
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-* 10 CO r-l <
4i 4j< b ( c<i i> 1-1
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bb
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po -S .c5 .
b b ' b ' si '
xb'-^t iis
It
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1 1 s
379
380 THE BREWER'S ANALYST
No. 1. This is a strong Burton water of fair purity. The
high proportion of sulphate of lime and carbonate of magnesia,
and the small proportion of carbonate of lime,, will be noted.
The carbonates would be precipitated on boiling, and all the
possible beneficial effects to be derived from the presence of
sulphate of lime in a brewing water may be obtained with from
50 to 75 grains per gallon of that salt. The chlorides are very
small in quantity.
No. 2. The distinguishing feature of this water, which is of
exceptional purity and an excellent one for stout and porter pro-
duction, is the small quantity of sulphate of lime and all other
constituents, with the exception of calcic carbonate, which is in
fair proportion and precipitable on boiling.
No. 3. The essential characteristic of this water, which is also
pure, is the high amount of chlorides and the small amount of
calcic sulphate. Such water is excellent for mild-ale production.
No. 4. Here we have a marked contrast between the previously
mentioned waters. It is a soft water and of extreme organic
purity. Such waters, however, are usually objectionable for
steam boilers, as they generally contain humic and other acids,
which have a marked corroding effect upon the boiler plates.
No. 5. Waters of this type are somewhat objectionable for
brewing on account of the nitric acid they contain.
Many such supplies are drawn from wells all over the kingdom,
particularly in the west of England and north as far as Edin-
burgh. Despite the nitrates, however, they are usually excellent
for brewing, provided a vigorous supply of yeast is employed for
the fermentations.
No. 6. This is a badly contaminated, town supply water, the
defilement being mainly of vegetable origin.
No. 7. Water drawn from a deep London well. It contains
sulphate and carbonate of soda and a large quantity of free
ammonia. It is excellent for black beers but unsuitable for pale
ales ; and even artificial manipulation cannot remedy this draw-
back, since after such treatment the chlorides are excessive.
No. 8 is a sample drawn from a well in Gloucestershire ; it is
similar in character to No. 7. It contains a large quantity of
free ammonia, but is nevertheless pure.
No. 9 is an extremely soft water, but peaty. Numerous
waters of this description are to be found, as drawn from shallow
wells, in various parts of the west of England, but particularly
in Yorkshire.
APPENDICES
COMPOSITION OF BOILER SCALE.
381
A.
B.
C.
D.
E.
Calcic carbonate
81-62
32-16
5-45
43-65
0-97
,, hydroxide
...
1370
...
,, sulphate
2 ; 50
5-64
1-69
3478
85-53
Magnesia hydroxide .
4-63
56-37
4-34
3-39
,, carbonate .
20-04
7-36
...
Sodium salts (chiefly
chlorides)
0-37
3-31
0-56
279
Oxide of iron
2-53
7-46
2-81
3-44
0-32
Silica
375
16-94
11-70
7'52
1-10
Organic matter
Moisture .
J4-60
/ 7-67
\ 6-78
j 0-89
j 1-55
\ 4-16
5 V 90
COMPOSITION OF KAINIT.
Potassic sulphate ......
Magnesic sulphate ... .
,, chloride ......
Potassic chloride ......
Sodic chloride . . .
Calcic sulphate ......
Silica . .
Moisture
COMPOSITION OF GYPSUM.
Calcic sulphate .
,, oxide .
Sulphuric anhydride
Moisture
33-56
46-56
COMPOSITION OF EPSOM SALT.
Magnesic sulphate
,, oxide
Sulphuric anhydride
Moisture
16-94
32-28
COMPOSITION OF CHARCOAL.
New.
Carbon, nitrogenous matter, etc. . . 9 '69
Calcic phosphate . . . . . .78*75
,, carbonate . . . . .8*41
,, sulphate 0'24
,, sulphide .... . O'll
Alkaline salts 1'50
Oxide of iron ..... 0'15
Silica . 1-15
21-3
14-5
12-4
2-0
34-6
1-7
0-8
12-7
100-0
80-12
19-88
100-00
49'22
50-78
100-00
Stock.
15-98
7578
5-72
0-96
0-24
Nil.
0-40
0-92
382
THE BREWER'S ANALYST
COMPOSITION OF COAL.
Caermarthenshire.
Pembrokeshire.
Glamorganshire .
t
3
a*
. * I-
a .
c
g
||
i
1
^
SB
S e
g 3 Lg ^
~d
11
1 I 11
o S
1
SC
a
P
g> L^d. 133
II"
fe
1
02
**
Carbon
Hydrogen
Oxygen
Nitrogen
92-17
3-10
2-22
1-08
91-16
311
2-74
0-91
88-70
I 7-40
94-18 ; 93-00
2 99 ' 3-08
0-50 1-67
0-76 0-54
92-17
3-10
2-22
108
91-44
3-46
2-58
0"21
93-12
)5-22
92-46
6-04
89-00
7-50
91-08
5-01
Sulphur
0-34
0-86
0-50
0-59
0-68
0-34
0-79
Ash .
1-09
1-1-2
3-40
0-98
1-03
1-09
1-52
I'M)
1-50
3-50
4-00
Total .
100-00
99-90
100-00
100-00
100-00
100-00
100-00
99-84
100-00
100-00
100-09
COMPOSITION OF COKE.
Cannel,
Steam
Coking Coals, Durham.
Cumber-
land.
Coal,
Wales.
Scotch Cannel.
5
5
^?n
>, -a"* 5
"* .
i
o a
.
va
cS
E
-s
a
1
!
15
l-ll
_t^ &-i *T?
"3
1
c
1
w
a
"1
1
^5^|
S
1
PQ
I
3
Carbon
92-55
91-88
91-56
93-41
85-84
57-65
87-92
79-69
29-50
76-52
69-93
Hydrogen
0-52
4-37
Oxygen
Nitrogen
} 1-38
/4-88
\0-51
Sulphur
0-81
0-84
1-21
0-91
0-86
2-02
0-90
2-26
0-25
0-41
0-37
Ash .
6-36
6-91
6-69
5-30
11-40
40-33
1-08
18-05
70-25
23-07
^9-70
Water
0-21
0-37
0-54
0-36
"
COMPOSITION OF BITUMINOUS COALS.
IM
111!
!j
?||d
V
8-gS Z
& 2Q
pa
li
CO>H
||l&
House.
Coking.
Gas.
Steam.
Peat.
Carbon
84-824
83-40
80-46
85-98
54-1
Hydrogen
5-522
4-40
5-08
470
5-6
Oxygen
Nitrogen
6'223\
2-075J
7-18
/ 6-80
\ 1-67
5-53
0-90
1 401
Sulphur
1-181
i-oo
1-65
0-59
Ash .
0-715
3-50
3'30
2-30
4-6
Water .
0-99
1-04
...
APPENDICES
COMPOSITION OF PEAT USED AS FUEL.
Carbon
Hydrogen
Oxygen .
Nitrogen .
Mineral matter
61-02
5'87
32-40
0-81
7-90
383
COMPOSITION OF WOOD USED AS FUEL.
Oak.
Beech.
Pine.
Carbon ...
48-12
49-46
50-62
Hydrogen
6-06
5-96
6-27
Oxygen ......
44-43
42-36
42-58
Nitrogen ......
1-22
Mineral matter .....
1-37
1*00
0'53
COMPOSITION OF THE PRINCIPAL CEREALS.
Wheat.
Barley.
Oats.
Rye.
Maize.
Rice.
Starch ....
62-3
57'0
56-1
54-9
54-8
78-8
Cellulose ....
8-3
8-3
1-0
6-4
14-9
0-2
Gum and sugar .
3'8
3-0
57
11-3
2-9
1-6
Fat and oils
1-2
2-5
4-6
2-0
4-7
o-i
Moisture ....
11-1
14-0
14-2
14-3
11-5
10-8
Albuminoids (soluble)
2-9
1-0
1-3
3-3
0-5
0-2
,, (insoluble)
8-0
12-2
147
5-5
8'4
7-0
Ash
2'4
2'0
2'4
2-3
2 '3
1-3
100-0
100-0
100-0
100-0
100-0
100-0
COMPOSITION OF OATMEAL.
Starch 60'96
Cellulose . . . . . . 6 '99
Albuminoids . . . . . .13*47
Fat and oil 7'30
Ash . 174
Moisture . . . . . . 9*54
Extract per quarter 78 Ibs. . 1.00 '00
384 THE BREWER'S ANALYST
TYPICAL ANALYSIS OF ENGLISH AND FOREIGN MALTS.
English.
Foreign.
1
2
3
4
Specific gravity 10 per cent, wort .
1027-5
1027-3
1025-1
1025-5
Extract per quarter
92-40
9172
84-33
85-68
Dry extract per cent.
71-24
70-72
65-02
66-06
Saccharifi cation period (minutes)
20
25
20
16
Colour of wort ....
5
4
5
3
Diastatic power ....
38
26
40-2
34-5
Acidity of wort ....
0-11
0-09
0-12
0-13
Mineral matter ....
1-06
1-08
2-30
2-10
Total albuminoids ....
10-20
9-10
8-40
9-20
Soluble .....
2-10
2-14
1-90
1-76
Insoluble ,,
8-10
6-96
6-50
7-44
Ready- formed soluble carbohydrates
16-51
17-72
11-13
13-12
Moisture
1-10
0-52
1-96
1-20
Arsenic trioxide, grains per Ib.
TtVU
T7tf
A
Free
BIOLOGICAL EXAMINATION.
Hours of Standing.
24
30
36
42
f Wort filtered from mash .
Sound.
Sound.
Sound.
Putrid.
' I Mash and wort together .
> >
Cloudy.
Putrid.
f Wort filtered from mash .
j
Sound.
Sound.
Cloudy.
2. -<
I Mash and wort together .
,,
>j
Cloudy.
Putrid.
i Wort filtered from mash .
Sound.
Cloudy.
3. -!
I Mash and wort together .
Cloudy.
Putrid.
( Wort filtered from mash .
>
Sound.
Cloudy.
Putrid.
4. -j
I Mash and wort together .
5)
APPENDICES
385
TYPICAL ANALYSIS OF ENGLISH HIGH-DRIED
AND PALE MALTS.
-
High Dried.
Pale.
Specific gravity 10 per cent, wort .
1027-80
10285-0
Extract per quarter ....
93'40
95-76
Dry extract per cent. ....
72-02
73-83
Diastatic power
31-00
44-20
Colour of wort
7-5
4-0
ANALYSIS CALCULATED ON 100 GRAMS OF MALT.
Dextrin . . .
17-37
1971
Maltose . .
35-36
35-91
Ready- formed soluble carbohydrates .
14-12
1311
Mineral matter .....
1-76
1-64
Soluble albuminoids ....
2-32
2-33
Acidity
0-27
0-23
Moisture .......
1-23
178
Grains .......
27-57
25-29
COMPOSITION OF MALT DUST.
Moisture 1'86
Mineral matter . . . . . 7 '63
Albuminoids 41-23
COMPOSITION OF BARLEY AND MALT.
Barley.
Malt.
Starch
47-0
46-0
3-0
16-0
Fat
2-5
2-5
Albuminoids (soluble) ....
,, (insoluble) ....
Cellular matter (digestible fibre)
Cellulose (woody fibre) ....
Ash
1-0 j
12-2 | 13 ' 2
14-0
4-3
2-0
( 3 ' 8 )
| 8-7 I 12 ' 5
13-5
47
2-3
14-0
2-5
100-0
100-0
25
386 THE BREWER'S ANALYST
COMPOSITION OF MAIZE AND RICE GRITS.
Maize Grits.
Rice Grits.
Starch
74-00
79-50
Oil
0-94
0-79
Albuminous matter ....
9-00
8-93
Ash
0-40
0-28
Moisture ......
10-61
9-82
Cellulose, etc
5-05
0-68
100-00
100-00
COMPOSITION OF FLAKED RICE AND MAIZE.
Flaked Maize.
Flaked Rice.
Starch
8070
81-75
Oil
1-20
0-30
Albuminous matter ....
9-69
8-62
Ash
0'46
0-34
Moisture ......
6-32
7-80
Cellulose, etc. .....
1-63
1-19
100-00
100-00
SOLUBLE NITROGENOUS CONSTITUENTS OF BARLEY AND OF THE
MALT MADE FROM IT, CALCULATED ON THE DRY SUBSTANCE.
Nitrogen
of
Albumin.
Nitrogen
of
Peptone.
Nitrogen of
Ammonium
Salts.
Nitrogen
of Amido
Acids.
Nitrogen
of
Amides.
Barley .
Per cent.
0-0600
Per cent.
0-0046
Per cent.
0-0169
Per cent.
0-0417
Per cent.
Barley steeped .
0-0354
0-0009
...
0-0294
...
Green malt
0-1671
0-0058
0-0290
0-1417
0-0505
Dried malt
0-1194
0-0233
0-0057
0-2257
0-0029
APPENDICES
COMPOSITION OF ENZYMES.
387
Carbon.
Hydrogen.
Nitrogen.
Sulphur.
Ash.
Malt diastase .
45-68
6-90
4-57-
6-08
'.,-'.
47-57
6-49
5-14
3'16
Yeast in vertase . ' . ,
43-10
7-80
4-30
...
6-10
,,
43-90
8-40
6-00
0-63
...
> j j
40-50
6-90
9-30
...
Ptyalin . . . : . .
43-10
7-80
11-86
...
6-10
Trypsin .
52-75
7-50
16-55
...
1770
Pepsin ....
53-20
670
17-80
...
Pancreatin
43-60
6-50
13-81
0-88
17-04
Emulsin
43-06
7-20
4-52
1-25
...
...
48-80
7-10
14-20
1-30
...
GELATINISATION TEMPERATURES OF
VARIOUS STARCHES.
Temperature
of Gelatinisation.
Variety of Starch.
F.
C.
Potato
149
65
Rice ....
158-167
70-75
Barley
176
80
Green malt
185
85
Kilned ,,
176
80
Wheat
167-176
75-80
Maize , . * .
158-167
70-75
Rye ....
176
80
Oats ....
185
85
388
THE BREWER S ANALYST
COMPOSITION OF RAW SUGARS AND SYRUPS.
&
cS
A^ feO
3
-^
3|,
111
?
if
PH
i!
ac
H
i
"3
S gi
2
?
O>
1
H
Cane-sugar .
75-12
90-94
76-40
80'34
48-10
51-33
34-40
Invert-sugar .
11-03
3-31
11-59
4-32
17-90
15-50
26-29
Other organic
matters
3-14
073
2-34
0-82
1-50
12-37
17-20
Ash ...
5'33
0-63
2-89
7-33
1-30
3-70
4-91
Moisture
5-38
4-39
6-78
719
31-20
17-10
17-20
100-00
100-00
100-00
100-00
100-00
100-00
100-00
COMPOSITION OF VARIOUS QUALITIES OF INVERT SUGAR.
A.
B.
C.
D.
Specific gravity 10 per cent, solution .
1032-45
1031-50
1032-40
1032-55
Extract per cwt. ....
36-34
35-28
36-28
36-45
Extract per cent, (allowance made
for ash)
82-46
78-93
80-19
'80-37
Invert-sugar
77-76
71-94
71-38
71-23
Cane-sugar .....
1-50
2-00
270
3-00
Albuminoids .....
80
79
89
Moisture
17-54
21-07
19-81
19-63
Mineral matter ....
1-50
2-50
3-50
3-70
Unfermentable bodies
1-70
1-69
1-82
1-55
PERCENTAGE COMPOSITION OF DRY EXTRACT.
Invert-sugar
94-30
91-14
89-02
88-63
Cane-sugar .....
1-82
2-53
3-36
3-74
Albuminoids .....
...
1-01
98
1*10
Mineral matter ....
1-82
3-17
4-37
4-60
Unfermentable bodies
2-06
2-15
2-27
1-93
100-00
100-00
100-00
100-00
APPENDICES
389
COMPOSITION OF PRIMING SYRUP.
Specific gravity of 20 per cent, solution . 104871
Extract per cwt. +. . . . 27*27
Extract per cent, (allowance made for ash) 61 '27
In vert- sugar ......
Cane-sugar . . . . .
Albuminoids ......
Moisture
Mineral matter .....
Unfermentable bodies .
PERCENTAGE COMPOSITION OF DRY EXTRACT.
Invert-sugar .
Cane-sugar .
Albuminoids .
Mineral matter
Unfermentable bodies
91-06
2'26
1-51
272
2'45
100-00
COMPOSITION OF VARIOUS QUALITIES OF GLUCOSE.
A.
B.
C.
D.
Specific gravity of 10 percent, solution
Extract per cwt
1035 00
39-20
1035-10
39-31
1033-00
36-96
103276
36-68
Extract per cent, (allowance made
for ash) .....
89-28
90-72
8378
8370
Dextrose . . .
75-28
73-34
61-67
65-92
Maltose ......
2-10
6-12
2-13
Dextrin ......
1-00
1-15
1-25
1-30
Albuminoids .....
20
45
60
57
Moisture ......
1072
9-28
16-22
16-30
Mineral matter ....
1-30
0-20
1-60
1-10
Unfermentable bodies
11-50
13-48
12-54
12-68
PERCENTAGE COMPOSITION OF DRY EXTRACT.
Dextrose ....
84-31
80-85
73-61
7875
Maltose ....
...
2-32
7-30
2-54
Dextrin ....
1-12
1-26
1-49
1-56
Albuminoids .
22
41
72
68
Mineral matter
1-46
32
1-92
1-32
Unfermentable bodies
12-89
14-85
14-96
15-15
100-00
100-00
100-00
100-00
390 THE BREWER'S ANALYST
COMPOSITION OF DEXTRINOUS CARAMEL.
Specific gravity of 20 per cent, solution . 1076 '80
Extract per cwt 43 '00
Extract per cent, (allowance made for ash) 98*21
Dextrin
Dextrose
Albuminoids. .....
Moisture .......
Mineral matter
Unfennentable bodies .
PERCENTAGE COMPOSITION OF DRY EXTRACT.
Dextrin 63 '07
Dextrose . . 1673
Albuminoids .... . '19
Mineral matter . . . . . 1*19
Unfermentable bodies . 18 '8 2
100-00
COMPOSITION OF FLUID CARAMEL.
Specific gravity of 20 per cent, solution . 1059 '26
Extract per cwt 33 '18
Extract per cent, (allowance made for ash) 74'86
Dextrose
Albuminoids
Moisture ......
Mineral matter .....
Unfermentable bodies .
PERCENTAGE COMPOSITION OF DRY EXTRACT.
Dextrose 76 '81
Albuminoids. ..... "37
Mineral matter 2 '38
Unfermentable bodies . 20 '44
100-00
APPENDICES
COMPOSITION OF YEAST.
391
%
Nageli and
Low.
Belohoubek.
Average.
Cellulose
37-0
49'6
43-3
Albumin .....
47-0
41-0
44-0
Fat
5-0
2'8
3-9
Extractive matter
4'0
1-1
2-5
Ash .
7-0
5'5
6-3
lOO'O
lOO'O
100-0
COMPOSITION OF THE ASH OF YEAST.
Yeast from Hard
Burton Water.
Yeast from Soft
Water.
Potassium phosphate
Magnesium ,', ...
Calcium ,, ...
Silica, alumina, etc. ....
63-1
21-0
13-6
2-3
93-9
5'6
traces
0-5
lOO'O
100-0
DECOMPOSITION OF SUGAR DURING FERMENTATION.
(PASTEUE.)
100 parts of dextrose yield :
Alcohol 48-3
Carbonic acid gas . . . . . 46 *4
Glycerol 2 '5 to 3'6
Succinic acid . . . . . 0*4 to 0*7
Cellulose and other bodies . . .1*3
COMPOSITION OF WET AND DRIED BREWERS' GRAINS.
(J. O'SULLIVAN. )
Wet Grains.
Dried Grains.
Water
Fat
Starch, sugar, and other carbohydrates
Albuminoids .....
Cellular matter (digestible fibre)
Cellulose (woody fibre)
Ash
75-0
1-2
1-3
47
11-8
5-0
I'O
7-5
3-8
5-0
19-1
40-2
19-6
4-8
lOO'O
100-0
392
THE BREWER'S ANALYST
COMPOSITION OF BREWERS' GRAINS COMPARED WITH THAT
OF SWEDE TURNIPS AND MANGOLDS.
(J. O'SULLIVAN.)
Brewers'
Wet
Grains.
Swede
Turnips.
Mangolds.
Water
Fat
75-0
1-2
89-3
0-2
88-5
O'l
Starch, sugar, and other carbohydrates
Albuminoids .....
Cellular matter (digestible fibre) .
Cellulose (woody fibre)
Ash
1-3
47
11-8 |
5-0 j
1-0
7'3
2-2
1-1
0-6
8'2
1-6
1-0
1-0
Total food constituents .
19-0
10-8
10-9
COMPOSITION OF MALT ROOTLETS.
Starch, sugar, and mucilage . . 3070
^Nitrogenous matter
Woody fibre
Ash
Fat .
Moisture .
29-50
2-90
3'30
32-90
070
100-00
* This figure is very large, and varies with different samples.
COMPOSITION OF BISULPHITE OF LIME : 100 PARTS
BY VOLUME AND BY WEIGHT.
Weight.
Volume,
Specific gravity
Total sulphurous acid
106 '9 grams.
6-52
1069-0
6-97
Free ,, ,, . .
3-83
4-10
Combined ,, ,,
2'68
2-87
Calcic sulphate
0-31
0-34
,, sulphite . .
4-62
4-94
Magnesic sulphite .
Sodic chloride ....
0-36
0-008
0-39
0-009
Iron oxide ....
0-003
0-004
Hyposulphites ....
Nil.
Nil.
COMPOSITION OF KALIUM METASULPHITE.
Moisture at 212 F. (100 C.) . . . 1'48
Loss by ignition 20 '49
Potassium 42 '73
Sulphuric acid 2'12
Sulphurous acid 55 '4 8
MOST PROBABLE COMBINATION.
Moisture 1*48
Potassic sulphate 4 '61
,, sulphite ... .68-25
Free sulphurous acid . . . .27*84
APPENDICES 393
COMPOSITION OF MONOSULPHITE OF LIME.
Lime 4379
Magnesia . ..**. . . . .0*57
Sulphuric acid 182
Sulphurous acid . . . . 41 '29
Chlorine 0'32
Iron and alumina . . . . .1*97
Silica . 0-16
MOST PROBABLE COMBINATION.
Calcic sulphite 7 7 '41
sulphate 3 '09
Magnesic sulphite . . . . .0*91
Calcic oxide ... . . 6'40
Sodic chloride 0'52
Iron and alumina . . . . . 1 '97
Silica 0'16
Moisture, carbon dioxide, etc., by difference 9 '54
100-00
COMPOSITION OF POTASSIO CARBONATE.
Total alkalinity 85 '94
Potassic chloride . . . . 2 '92
,, sulphate 0'66
Moisture . 10 '42
COMPOSITION OF CAUSTIC POTASH.
Total alkalinity 87 '92
Potassic chloride . . . . . 6 '54
,, sulphate . . . . 1'43
Moisture 0'79
Carbon dioxide, traces of iron, etc. . . 3*22
COMPOSITION OF CAUSTIC SODA.
Total alkalinity . . . . . 96 '83
Sodic chloride 1 '72
,, sulphate ...... '58
Moisture . *89
APPENDIX B.
TABLES AND FACTORS.
MULTIPLIERS REQUIRED IN VOLUMETRIC ANALYSIS.
Normal sulphuric acid, H 2 S0 4 . . 1 c.c. = 0'049 gram H S0 4 .
=0-048 S0 4 .
=0-040 S0 3 .
,, =0-053 ,, Na-jCO,.
Normal hydrochloric acid, HC1 .
Normal nitric acid, HN0 3
Normal oxalic acid, H 2 C 2 4
Normal sodium hydrate, NaHO
Normal potassium hydrate, KHO
Normal sodium carbonate,
Calcium (Ca = 40)
=0-090
1 c.c. =0-0365
,, =0-0355
1 c.c. =0-063
,, =0-062
=0-054
1 c.c. = 0-063
=0-045
1 c.c. =0-040
,, =0-031
1 c.c. =0'056
=0-047
1 c.c. = 0-053
=0-030
, =0-022
1 c.c. permanganate
= 0-0028
= 0-0050
;; ;; =0-0086
1 c.c. normal oxalic acid =0'0280
Cryst. oxalic acid x 0'444 = CaO.
Double iron salt x '07 143 = CaO.
albumin.
HCl
Cl.
HN0 3 .
N0 3 .
N 2 5 .
H 2 C 2 <> 4 , 20H
H 2 C 2 4 .
NaHO.
Na.0.
KHO.
K 9 0.
Na 2 C0 3
C0 3 .
C0 2 .
CaO.
CaCO 3 .
CaS0 4 , 20H 2 .
CaO.
1 c.c. silver solution
Chlorine (01 = 35 '37)
= 0-003537 gram 01.
= 0-005837 NaCl.
1 c.c. arsenious or hyposulphite solution = 0*003537 ,, Cl.
1 litre of chlorine at C. and 760 mm. weighs 3'17 grams.
394
APPENDICES 395
Chromium (Or = 52 '4)
Metallic iron x '3123 = Cr.
xO-5981 = Cr0 3 .
xO'8784 = K 2 Cr 2 7 .
- x 1-926 = PbCr0 4 .
Double iron salt x '0446 = Cr.
xO'0854 = Cr0 3 .
xO-1255 = K 2 Cr 2 7 .
xO-0275 = PbCr0 4 .
N
1 c.c. _ solution = 0-003349 gram Cr0 3 .
= 0-00492 K 2 Cr 2 7 .
Copper (Cu = 63)
1 c.c. solution = '0063 gram Cu.
Iron x 1-125 = copper.
Double iron salt xO'1607 = ,,
Cyanogen (CN = 26)
1 c.c. _ silver solution =0*0052 gram ON.
= 0-0054 HCN.
= 0-01302 ,, KCN.
1 c.c. ^-iodine solution = 0-003255 ,, KCN.
Gold (Au = 196-5)
1 c.c. normal oxalic acid = '0655 gram Au.
Iodine (I = 126 -5)
1 c.c. hyposulphite= 0-01265 gram iodine.
1 c.c. ^ iodine = 0*0032 S0 2 .
Iron(Fe = 56)
1 c.c. permanganate, bichromate, or hyposulphite = 0-005 6 Fe.
= 0-0072 FeO.
= 0-0017 H 2 S.
= 0-0056 CaO.
Lead (Pb = 206-4)
1 c.c. permanganate = '01032 gram Pb.
1 c.c. normal oxalic acid = 0-1032 ,, Pb.
Metallic iron x 1 -842 = Pb.
Double iron salt x '263 = Pb.
Manganese (Mn = 55)
MnO = 7l. Mn0 2 = 87.
Metallic iron x 0*491 =Mn.
xO -63393 = MnO.
x 0-7768 =Mn0 2 .
Double iron salt x 0-0911 =MnO.
x 0-111 =MN0 2 .
Cryst. oxalic acid xO'6916 =Mn0 2 .
1 c.c. solution =0-00355 gram MnO.
,, x 0-00435 MnO,.
396 THE BREWER'S ANALYST
Mercury (Hg = 200)
Double iron salt x 0-5104 Hg.
x 0-6914 = HgCl 2 .
1 c.c. solution = 0-0200 gram Hg.
. =0-0208 ,, Hg 2 0.
=0-0271 HgCl 2 .
Nitrogen as nitrates and nitrites
N 2 5 = 108. N. 2 3 = 76.
Normal acid x 0*0540 =N 2 O 5 .
x 0-1011 = KN0 3 .
Metallic iron x 0*3750 = HN0 3 .
x 0-6018 = KN0 3 .
,, x 0-3214 = N 2 5 .
Potassic ferrocyanide (K 4 FeCy 6 , 30H 2 = 422)
Metallic iron x 7*541 =cryst. potassic ferrocyanide.
Double iron salt x 1 '077 = , , , ,
Potassic ferricyanide (K 6 Fe 2 Cy 12 = 658)
Metallic iron x5'88 = potassic ferricyanide.
Double iron salt x 1 -68 = ,, ,,
~ hyposulphite x 0'0329 =
Silver(Ag=107-66)
1 c.c. 5 NaCl = 0-010766 gram Ag.
=0-016966 AgN0 3 .
Sulphuretted hydrogen (H 2 S = 34)
"NT
1 c.c. arsenious solution = "00255 gram H 2 S.
Tin(Sn = 118)
Metallic iron x 1 -0536 = Sn.
Double iron salt x 0'1505 = Sn.
Factor for iodine or permanganate solution 0*0059.
Zine(Zn = 65)
Metallic iron xO'5809 =Zn.
,, ,, x 0*724 =ZnO.
Double iron salt x 0*08298 = Zn.
,, x 0-1034 =ZnO.
1 c.c. solution = 0*00325 gram Zn.
APPENDICES
397
TABLE SHOWING EXTRACT IN POUNDS PER QUARTER AND DRY EXTRACT
PER CENT. OBTAINED FROM PALE OR COLOURED MALT OR MALT AND
RAW GRAIN, MASHED TO OBTAIN A 10 PER CENT. SOLUTION.
Example. Specific gravity 10 per cent, solution less lUOOx3'36=lbs. extract per quarter.
,, ,, X "36 =lbs. per barrel.
,, ,, ,, ,, -f3'86 = dry extract per cent.
(BAILEY.)
Specific
Gravity.
Lbs. per
Barrel.
Extract
per
Quarter.
Dry Ex-
tract per
Cent.
Specific
Gravity.
Lbs. per
Barrel.
Extract
per
Quarter.
Dry Ex-
tract per
Cent.
1017-0
6-12
57-12
44-04
1021-0
7-56
70-56
54-40
1
6-15
57-75
44-30
1
7-59
70-89
54-66
2
6-19
5779
44-55
2
7-63
71-23
54-92
3
6-22
58-12
44-81
3
7-66
71-56
55-18
4
6-26
58-26
45-07
4
7-70
71-90
55-44
5
6'30
58-80
45-33
5
7-74
72-24
55-69
6
6*33
59-13
45-59
6
7-77
72-57
55-95
7
6-37
59-47
45-85
7
7-81
72-91
56-21
8
6-40
59-80
46-11
8
7-84
72-58
56-47
9
6-44
60-14
46-37
9
7-88
73-58
56-73
1018-0
6-48
60-48
46-63
1022-0
7-92
73-92
56-99
1
6'51
60-81
46-89
1
7-98
74-25
57-25
2
6'55
61-15
47-15
2
7-99
74-59
57-51
3
6-58
61-48
47-40
3
8-02
74-92
57-77
4
6-62
61-82
47-66
4
8-06
75-26
58-03
5
6-66
62-16
47-92
5
8-10
75-60
58-29
6
6-69
62-49
48-18
6
8-13
75-93
58-54
7
673
62-83
48-44
"7
8-17
76-27
58-80
8
6-76
63-16
4870
8
8-20
76-60
59-06
9
6-80
63-50
48-96
9
8-24
76-94
59-32
1019-0
6-84
63-84
49-22
1023-0
8-28
77-28
59-58
1
6-87
64-17
49-48
1
8-31
77-61
59-84
2
6-91
64-51
49-74
2
8-35
77-95
60-10
3
6'94
64-84
50-00
3
8-38
78-28
60-36
4
6-98
65-18
50-25
4
8-42
78-62
60-62
5
7'02
65-52
50-51
5
8-46
78-96
60-88
6
7-05
65-85
50-77
6
8-49
79-29
61-13
'7
7-09
6619
51-03
7
8-53
79-63
61-39
8
7'12
66-32
51-29
8
8-56
79-96
61-65
9
7-16
66-86
51-55
9
8-60
80-30
61-91
1020-0
7-20
67-20
51-81
1024-0
8-64
80-64
62-17
1
7-23
67*53
52-07
1
8-67
80-97
62-43
2
7'27
67-87
52-33
2
8-71
81-31
62-69
3
7-30
68-20
52-59
3
8-74
81-64
62-95
4
7'34
68-54
52-84
4
8-78
81-98
63-21
5
7-38
68-88
53-10
5
8-82
82-32
63-47
6
7'41
69-21
53-36
6
8-85
82-65
6373
7
7-45
69-55
53-62
7
8-89
82-99
63-98
8
7'48
69-88
53-88
8
8-92
83-32
64-24
9
7-52
70-02
54-14
9
8-96
83-66
64-50
398
THE BREWER'S ANALYST
TABLE SHOWING EXTRACT IN POUNDS PER QUARTER, ETC. continued.
Specific
Gravity.
Lbs. per
Barrel.
Extract
per
Quarter.
Dry Ex-
tract per
Cent.
Specific
Gravity.
Lbs. per
Barrel.
Extract
per
Quarter.
Dry Ex-
tract per
Cent.
1025-0
9-00
84-00
6476
1029-0
10-44
97-44
75-12
1
9-03
84-33
65-02
1
10-47
97-77
75-38
2
9-07
84-67
65-28
2
10-51
98-11
75-64
3
9-10
85-00
65-54
3
10-54
98-44
75-90
4
9-14
85-34
65-80
4
10-58
98-78
76-16
5
9-18
85-68
66-06
5
10-62
99-12
76-42
6
9-21
86-01
66-32
6
10-65
99-45
76-68
7
9-25
86-35
66-58
7
10-69
99-79
76-94
8
9-28
86-68
66-83
8
10-72
100-12
77-20
9
9-32
87-02
67-09
9
1076
100-46
77-46
1026-0
9-36
87-36
67-35
1030-0
10-80
100-80
77-72
1
9-39
87-69
67-61
1
10-83
101-13'
78-00
2
9-43
88-05
67-87
2
10-87
101-47
78-26
3
9-46
88-36
68-13
3
10-90
101-80
78-52
4
9-50
88-70
68-39
4
10-94
102-14
78-78
5
9-54
89-04
68-65
5
10-98
102-48
79-01
6
9-57
89-37
68-91
6
11-01
102-81
79-27
7
9-61
89-71
69-17
7
11-05
103-15
79-53
8
9-64
90-04
69-43
8
11-08
103-48
79-79
9
9-68
90-38
69-68
9
11-12
103-82
80-05
1027-0
9-72
9072
69-94
1031-0
11-16
104-16
80-31
1
9-75
91-05
70-20
1
11-19
104-46
80-56
2
9-79
91-39
70-46
2
11-23
104-83
80-82
3
9-82
9172
70-72
3
11-26
105-16
81-08
4
9-86
92-06
70-98
4
11-30
105-50
81-34
5
9-90
92-40
71-24
5
11-34
105-84
81-60
6
9-93
92-73
71-50
6
11-37
106-17
81-86
7
9-97
93-07
71-76
*7
11-41
106-51
82-12
8
10-00
93-40
72-02
8
11-44
106-84
82-38
9
10-04
93-74
72-27
9
11-48
107-18
82-64
1028-0
10-08
94-08
72-53
1032-0
11-52
107-52
82-90
1
10-11
94-41
72-79 '
1
11-55
107-85
83-16
2
10-15
94-75
73-05
2
11-59
108-19
83-41
3
10-18
95-08
73-31
3
11-62
108-52
83-68
4
10-22
95-42
73-57
4
11-64
108-86
83-93
5
10-26
95-76
73-83
5
11-70
109-20
84-09
6
10-29
96-09
74-09
6
11-73
109-54
84-45
7
10-33
96-43
74-35
7
11-77
109-87
84-71
8
10-36
96-76
74-61
8
11-80
110-20
84-97
9
10-40
97-10
74-87
9
11-84
110-54
85-23
1033-0
11-88
110-88
85-49
APPENDICES
399
TABLE SHOWING PERCENTAGE MATTERS SOLUBLE IN COLD WATER FROM
WHICH MAY BE CALCULATED THE READY-FORMED SOLUBLE CARBO-
HYDRATES. (MALT ANALYSIS BAILEY.)
Example. Specific gravity of cold-water extract =1005'00. 1005*00- 1000-00 = 5'00-f-
3-86 = 1-209 dry solids per 100 c.c. T209xlO (10 per cent, solution) =12-09 per cent.
Deduct percentage of albuminoids, ash and acid, as found by analysis ; or, taking these as
equal to 4 per cent., the balance equals ready-formed soluble carbohydrates.
Specific
Gravity.
Dry Solids
per 100 c.c.
Matters soluble
in Cold Water.
Specific
Gravity.
Dry Solids
per 100 c.c.
Matters soluble
in Cold Water.
lOOl'O
0-25
2-50
6
1-450
14-50
1
0-28
2-80
7
1-476
14-76
2
0-31
3-10
8
1-502
15-02
3
0-33
3-30
9
1-528
15-28
4
0-36
3-60
1006-0
1-552
15-52
5
0-38
3-80
1
1-580
15-80
6
0-41
4-10
2
1-606
16-06
7
0-44
4-40
3
1-632
16-32
8
0-46
4-60
4
1-658
16-58
9
0-49
4-90
5
1-683
16-83
1002-0
0-51
5-10
6
1-709
17-09
1
0-54
5-40
7
1-735
17-35
2
0-56
5-60
8
1761
17-61
3
0-59
5-90
9
1-787
17-87
4
0-62
6-20
1007-0
1-813
18-13
5
0-64
6-40
1
1-839
18-39
6
0-67
670
2
1-865
18-65
7
0-69
6-90
3
1-891
18-91
8
0-72
. 7-20
4
1-917
19-17
9
0-75
7-50
5
1-943
19-43
1003-0
0-77
770
6
1-968
19-68
1
079
7-90
7
1-994
19-94
2
0-82
8-20
8
2-020
20-20
3
0-85
8-50
9
2-046
20-46
4
0-88
8-80
1008-0
2-072
2072
5
0-90
9-00
1
2-098
20-98
6
0-93
9-30
2
2-124
21-24
7
0-95
9-50
3
2-150
21-50
8
0-98
9-80
4
2-176
2176
9
1-01
10-10
5
2-202
22-02
1004-0
1-03
10-30
6
2-2-28
22-28
1
1-06
10-60
7
2-253
22-53
2
1-08 i 10-80
8
2-279
22-79
3
111
11-10
9
2-305
23-05
4
114
11-40
1009-0
2-331
23-31
5
116
11-60
1
2-357
23-57
6
119
11-90
"2
2-383
23-83
7
1-21
12-10
3
2-409
24-09
8
1-24
12-40
4
2-435
24-35
9
1-26
12-60
5
2-461
24-61
1005-0
1-295
12-95
6
2-487
24-87
1
1-321
13-21
"7
2-512
25-12
2
1-344
13-44
8
2-538
25-38
3
1-373
13-73
9
2-564
25-64
4
1-398
13-98
1010-0
2-590
25-90
5
1-424
14-24
400
THE BREWER'S ANALYST
REDUCING VALUES OF VARYING QUANTITIES OF DEXTROSE, LEVULOSE, AND
INVERT-SUGAR UNDER STANDARD CONDITIONS. (From Brown, Morris,
and Millar, Journal of the Chemical Society, 1897, vol. Ixxi. p. 281.)
Dextrose.
Levulose.
Invert-Sugar.
&o
bCoJ
off
GQ
C M
GC
G 02
H
|
rf
rf
|
11
2
rf
03
g
'S -73
C 3
B
O
o5
|
O
O
O
H
O
4
s
1
Is
1
O
O
1
O
5
o
. I 1
Levulos
3
O
o
O c8
o
82
Invert-Su
s
o
O
o
050
1030
1289
2-060
050
0923
1155
1-846
050
0975
1221
055
1134
1422
2-061
055
1027
1287
1-858
055
1076
1349
060
1238
1552
2-063
060
1122
1407
1-870
060
1176
1474
065
1342
1682
2-062
065
1216
1524
1-871
065
1275
1598
070
1443
1809
2-061
070
1312
1645
1-874
070
1373
1721
075
1543
1935
2-058
075
1405
1761
1-873
075
1468
1840
080
1644
2061
2-055
080
1500
1881
1-875
080
1566
1963
085
1740
2187
2-046
085
1590
1993
1-871
085
1662
2084
090
1834
2299
2-038
090
1686
2114
1-873
090
1755
2200
095
1930
2420
2-033
095
1774
2224
1-868
095
1848
2317
100
2027
2538
2-027
100
1862
2331
1-862
100
1941
2430
105
2123
2662
2-024
105
1952
2447
1-859
105
2034
2550
110
2218
2781
2-020
110
2040
2558
1-855
110
2128
2668
115
2313
2900
2-012
115
2129
2669
1-851
115
2220
2783
120
2404
3014
2-003
120
2215
2777
1-846
120
2311
2898
125
2496
3130
1-997
125
2303
2887
1-843
125
2400
3009
130
2585
3241
1-990
130
2390
2997
1-840
130
2489
3121
135
2675
3354
981
135
2477
3106
1-834
135
2578
3232
140
2762
3463
973
140
2559
3209
1-828
140
2663
^3339
145
2850
3573
964
145
2641
3311
1-822
145
2750
3448
150
2934
3673
956
150
2723
3409
1-815
150
2832
3546
155
3020
3787
948
155
2805
3517
1-811
155
2915
3655
160
3103
3891
940
160
2889
3622
1-806
160
3002
3764
165
3187
3996
1-931
165
2972
3726
1-803
165
3086
3869
170
3268
4098
1-922
170
3053
3828
1-799
170
3167
3971
175
3350
4200
1-914
175
3134
3930
1-793
175
3251
4076
180
3431
4302
1-906
180
3216
4032
1-787
180
3331
4177
185
3508
4399
1-896
185
3297
4134
1-782
185
3410
4276
190
3590
4501
1-890
190
3377
4234
1-777
190
3490
4376
195
3668
4599
1-881
195
3457
4335
1-773
195
3570
4476
200
3745
4689
1-872
200
3539
4431
1-769
200
3650
4570
205
3822
4792
1-863
205
3616
4534
1-765
205
3726
4672
The sugar values for weights of Cu or CuO lying between any of the weights
given in the above table must be arrived at by calculation.
Example. The amount of dextrose corresponding with '2385 gram Cu is
required. On referring to the table, "2313 gram Cu corresponds with "115 gram
dextrose, and '2404 gram Cu with -120 gram dextrose. Hence '2404 - -2313 =
0091 gram Cu and '120 - '115 = '005 gram dextrose. Therefore '0091 gram Cu
= -005 gram dextrose in the portion of the table used. Now the difference
between the amount of Cu found, '2385, and the nearest lower amount in the
table, -2313 gram, is '0072 gram. Hence '0091 : '005 : : '0072 : '004. There-
fore '115+ '004 = '119 gram dextrose, corresponding to '2385 gram Cu,
APPENDICES
401
REDUCING VALUES OF VARYING QUANTITIES OF MALTOSE UNDER STANDARD
CONDITIONS. (From Brown, Morris, and Millar, Journal of the Chemical
Society, 1897, vol. Ixxi. p. 100.)
Maltose.
Grams.
Cu.
Grams.
CuO.
Grams.
Cu. Corre-
sponding to
iGram
Maltose.
Maltose.
Grams.
Cu.
Grams.
CuO.
Grams.
Cu. Corre-
sponding to
IGram
Maltose.
070
0772
0966
1-1029
190
2072
2593
1-0953
075
0826 '1034
1-1026
195
2126
2661
1-0949
080
0880
1102
1-1023
200
2180
2729
1-0946
085
0934
1169
1-1020
205
2234
2797
1-0943
090
0988
1237
1-1017
210
2288
2865
1-0940
095
1042
1305
1-1013
215
2342
2933
1-0937
100
1097
1373
1-1010
220
2397
3000
1-0933
105
1151
1441
1-1007
225
2451
3068
1-0930
110
1205
1509
1-1004
230
2505
3136
1-0927
115
1259
1576
1-1001
235
2559
3203
1-0924
120
1313
1644
1-0997
240
2613
3272
1-0921
125
1367
1712
1-0994
245
2667
3340
1-0917
130
1422
1779
1-0991
250
2722
3407
1-0914
135
1476
1848
1-0988
255
2776
3475
1-0911
140
1530
1916
1-0985
260
2830
3543
1-0908
145
1584
1983
1-0981
265
2884
3610
1-0905
150
1634
2051
1-0978
270
2938
3678
1-0901
155
1692
2119
1-0975
275
2992
3747
1-0898
160
1747
2186
1-0972
280
3047
3814
1-0895
165
1801
2254
1-0969
285
3101
3882
1-0892
170
1855
2323
1-0965
290
3155
3950
1-0889
175
1909
2490
1-0962
295
3209
4017
1-0885
180
1963
2458
1-0959
300
3264
4085
1-0882
185
2017
2526
1-0956
305
3318
4154
1-0879
OTTO'S TABLE SHOWING THE PERCENTAGES OF H 2 S0 4 CORRESPONDING
TO THE DILUTE ACID OF VARIOUS SPECIFIC GRAVITIES AT 15 C.
Per
cent, of
H2S0 4 .
Specific
Gravity.
Per
cent, of
H 2 S0 4 .
Specific
Gravity.
Per
cent, of
H 2 S0 4 .
Specific
Gravity.
Per
cent, of
H 2 S0 4 .
Specific
Gravity.
100
1-8426
75
1-6750
50
1-3980
25
1-1820
99
1-8420
74
1-6630
49
1-3866
24
1-1740
98
1-8406
73
1-6510
48
1-3790
23
1-1670
97
1-8400
72
1-6390
47
1-3700
22
1-1590
96
1-8384
71
1-6270
46
1-3610
21
1-1516
95
1-8376
7u
1-6150
45
1-3510
20
1-1440
94
1-8356
69
1-6040
44
1-3420
19
1-1360
93
1-8340
68
1-5920
43
1-3330
18
1-1290
92
1-8310
67
1-5800
42
1-3240
17
1-1210
91
1-8270
66
1-5860
41
1-3150
16
1-1136
90
1-8220
65
1-5570
40
1-3060
15
1-1060
89
1-8160
64
1-5450
39
1-2976
14
1-0980
88
1-8090
63
1-5340
38
1-2890
13
1-0910
87
1-8020
62
1-5230
37
1-2810
12
1-0830
86
1-7940
61
1-5120
36
1-2720
11
1-0756
85
1-7860
60
1-5010
35
1-2640
10
1-0680
84
1-7770
59
1-4900
34
1-2560
9
1-0610
83
1-7670
58
1-4800
33
1-2476
8
1-0536
82
1-7560
57
1-4690
32
1-2390
7
1-0464
81
1-7450
56
1-4586
31
1-2310
6
1-0390
80
1-7340
55
1-4480
30
1-2230
5
1-0320
79
1-7220
54
1-4380
29
1-2150
4
1-0256
78
1-7100
53
1-4280
28
1-2066
I
1-0190
77
1-6980
52
1-4180
27
1-1980
2
1-0130
76
1-6860
51
1-4080
26
1-1900
1
1-0064
26
402
THE BREWER'S ANALYST
URE'S TABLE SHOWING THE PERCENTAGES OF HCL. CORRESPONDING TO
THE DILUTE ACID OF VARIOUS SPECIFIC GRAVITIES AT 15 C.
Specific Gravity.
(M
gfcj
So
5
^
3*
*o &
-iJ O
<r*
<X) .
t!
Specific Gravity.
H
O
~ t-3
1
C
*T3
36
"o
4*0
g^
i-l
<*-!
0>
P-I
Specific Gravity.
Per cent, of
HCL.
d
ii
'o
W 02
*
g^
O i 1
<3 "o
PH
1-2000
40777
100
1-328
26-913
66
1-0657
13-456
33
1-1982
40-369
99
1-308
26-505
65
1-0637
13-049
32
1-1964
39-961
98
1-1287
26-098
64
1-0617
12-641
31
1-1946
39-554
97
1-1267
25-690
63
1-0597
12-233
30
1-1928
39-146
96
1-1247
25-282
62
1-0577
11-825
29
1-1910
38738
95
1-1226
24-847
61
1-0557
11-418
28
1-1893
38-330
94
1-1206
24-466
60
1-0537
11-010
27
1-1875
37-923
93
1-1185
24-058
59
1-0517
10-602
26
1-1857
37-516
92
1-1164
23-650
58
1-0497
10-194
25
1-1846
37-108
91
1-1143
23-242
57
T0477
9-786
24
1-1822
36-700
90
1-1123
22-834
56
1-0457
9-379
23
1-1802
36-292
89
1-1102
22-426
55
1-0437
8-971
22
1-1782
35-884
88
11082
22-019
54
1-0417
8-563
21
1-1762
35-476
87
1-1061
21-611
53
1-0397
8-155
20
1-1741
35-068
86
1-1041
21-203
52
1-0377
7747
19
1-1721
34-660
85
1-1020
20-796
51
1-0357
7-340
18
1-1701
34-252
84
1-1000
20-388
50
1-0337
6-932
17
1-1681
33-845
83
1-0980
19-980
49
1-0318
6-524
16
T1661
33-437
82
1-0960
19-572
48
1-0298
6116
15
1-1641
33-029
81
1-0939
19-165
47
1-0279
5709
14
1-1620
32-621
80
1-0919
18-757
46
1-0259
5-301
13
11599
32-213
79
1-0899
18-349
45
1-0239
4-893
12
1-1578
31-805
78
1-0879
17-941
44
1-0220
4-486
11
1-1557
31-398
77
1-0859
17-534
43
1-0200
4-078
10
T1536
30-990
76
1-0838
17-126
42
1-0180
3-670
9
1-1515
30-582
75
1-0818
16-718
41
1-0160
3-262
8
1-1494
30-174
74
1-0798
16-310
40
1-0140
2-854
7
1-1473
29767
73
1-0778
15-902
39
1-0120
2-447
6
1-1452
29-359
72
1-0758
15-494
38
roioo
2-039
5
1-1431
28-951
71
1-0738
15-087
37
1-0080
1-631
4
1-1410
28-544
70
1-0718
14-679
36
1-0060
1-224
3
1-1389
28-136
69
1-0697
14-271
35
1-0040
0-816
2
1-1369
27-728
68
1-0677
13-863
34
1-0020
0-408
1
1-1349
27-321
67
APPENDICES
403
URE'S TABLE SHOWING THE PERCENTAGES OF HN0 3 CORRESPONDING TO
THE DILUTE ACID OF VARIOUS SPECIFIC GRAVITIES AT 15 C.
HN0 3
per
cent.
Specific Gravity
HN0 3
per
cent.
Specific Gravity
HN0 3
per
cent.
Specific Gravity.
AtO.
At 15.
AtO.
At 15
At 0.
At 15.
100-00
1-559
1-530
72-39
1-455
1-432
46-64
1-312
1-295
99-84
1-559
1-530
71-24
1-450
1-429
45-00
1-300
1-284
9972
1-558
1-530
69-96
1-444
1-423
43-53
1-291
1-274
99-52
1-557
1-529
69-20
1-441
1-419
42-00
1-280
1-264
97-89
1-551
1-523
68-00
1-435
1-414
41-00
1-274
1-257
97-00
1-548
1-520
67-00
1-430
1-410
40-00
1-267
1-251
96-00
1-544
1-516
66-00
1-425
1-405
39-00
1-260
1-244
95-27
1-542
1-514
65-07
1-420
1-400
37*95
1-253
1-237
94-00
1-537
T509
64-00
1-415
1-395
36-00
1-240
1-225
93-01
1-533
1-506
63-59
1-413
1-393
35-00
1-234
1-218
92-00
1-529
1-503
62-00
1-404
1 '386
33-86
1-226
1-211
91-00
1-526
1-499
61-21
1-400
1-381
32-00
1-214
1-198
90-00
1 -522
1-495
60-00
1-303
1-374
31-00
1-207
1-192
89-56
1-521
1-494
59-59
1-391
1-372
30-00
1-200
1-185
88-00
1-514
1-488
58-88
1-387
1-368
29-00
1-194
1-179
87-45
1-513
1-486
58-00
1-382
1-363
28-00
1-187
1-172
86-17
1-507
1-482
57-00
1-376
1-358
27-00
1-180
1-166
85-00
1-503
1-478
56-10
1-371
1-353
25-71
1-171
1-157
84-00
1-499
1-474
55-00
1-365
1-346
23-00
1-153
1-138
83-00
1-495
1-470
54-00
1-359
1-341
20-00
1-132
1-120
82-00
1-492
1-467
53-81
1-358
1-339
17-47
1-115
1-105
80-96
1-488
1-463
53-00
1-353
1-335
15-00
1-099
1-089
80-00
1-484
1-460
52-33
1-349
1-331
13-00
1-085
1-077
79-00
1-481
1-456
50-99
1-341
1-323
11-41
1-075
1-067
77-66
1-476
1-451
49-97
1-334
1-317
7-22
1-050
1-045
76-00
1-469
1-445
49-00
1-328
1-312
4-00
1-026
1-022
75-00
1-465
1-442
48-00
1 -321
1-304
2-00
1-013
1-010
74-01
1-462
1-438
47-18
1-315
1-298
o-oo
1-000
0-999
73-00
1-457
1-435
404
THE BREWER'S ANALYST
TABLE SHOWING THE PERCENTAGE OF K 2 AND KHO IN SOLUTIONS
OF CAUSTIC POTASH OF VARIOUS SPECIFIC GRAVITIES AT 15 C.*
Per cent,
of KjO.
Per cent,
of KHO.
Specific
Gravity.
Per cent,
of K 2 0.
j
Per cent. Specific
of KHO. Gravity.
5658
0-674
1-0050
23-764
28-303 1-2648
1-697
2-021
1-0153
24-895
29-650 1-2805
2-829
3-369
1-0260
26-027
30-998 1-2966
3-961
4717
1-0369
27-158
32-345 1-3131
5-002
5-957
1-0478
28-290
33-693 1-3300
6-224
7-412
1-0589
29-34
34-94 1-30
7-355
8760
1-0703
30-74
36-61 1-32
8-487
10-108
1-0819
32-14
38-28 1-34
9-619
11-456
1 -0938
33-46
39-85 1-36
10-750
12-803
1-1059
34-74
41-37 1-38
11-882
14-151
1182
35-99
42-86 1-40
13-013
15-498
1308
37-97
45-22 1-42
14-145
16-846
1437
40-17
47-84 1-44
15-277
18-195
1568
42-31
50-39 1-46
16-408
19-542
1702
44-40
52-88 1-48
17'540
20-890
1839
46-45
55-32 1-50
18-671
22-237
1979
48-46
5771 1-52
19-803
23-585
2122
50-09
59-65 1-54
20-935
24-933
2268
51-58
61-43 1-56
21-500
25-606
1-2342
53-06
63-19 1-58
22-632
26-954
1-2493
|
* Tiinnermann and Richter.
TABLE SHOWING THE PERCENTAGE OF Na 2 IN SOLUTIONS OF CAUSTIC
SODA OF VARIOUS SPECIFIC GRAVITIES AT 15 C.f
Per cent, of
Specific
Per cent, of
Specific
Per cent.
Specific
Na 2 0.
Gravity.
Na 2 0.
Gravity.
of NasjO.
Gravity.
302
1 -0040
10-879
1-1630
21-154
1-3053
604
1 -0081
11-484
1-1734
21-758
1-3125
1-209
1-0163
12-088
1-1841
21-894
1-3143
1-813
1 -0246
12-692
1-1948
22-363
1-3198
2-418
1-0330
13-297
1 -2058
22-967
1-3273
3-022
1-0414
13-901
1-2178
23-572
1-3349
3-626
1-0500
14-506
1-2280
24-176
1-3426
4-231
1-0587
15-110
1-2392
24-780
1-3505
4-835
1-0675
15-714
1 "2453
25-385
1-3586
5'440
1-0764
16-319
1-2515
25-989
1-3668
6-044
1-0855
16-923
1-2578
26-594
1-3751
6-648
1-0948
17-528
1-2642
27-200
1 '3836
7-253
1-1042
18-132
1-2708
27-802
1-3923
7-857
1-1137
18-730
1-2775
28-407
1-4011
8-462
1-1233
19-341
1 -2843
29-011
1-4101
9-066
1-1330
19-945
1-2912
29-616 i 1-4193
9-670
1-1428
20-550
1 "2982
30-220 1-4285
10-275
1-1528
t Tunneraaann.
APPENDICES
405
TABLE SHOWING THE PERCENTAGE OF NH 3 IN AQUEOUS SOLUTIONS
OF THE GAS OF VARIOUS SPECIFIC GRAVITIES AT 14 C.*
Specific
NH 3
Specific
NH 3
Specific
NH 3
Gravity.
per cent.
Gravity.
per cent.
Gravity.
per cent.
0-8844
36
0-9133
24
0-9520
12
0-8864
35
0-9162
23
0-9556
11
0-8885
34
0-9191
22
0-9593
10
0-8907
33
0-9221
21
0-9631
9
0-8929
32
0-9251
20
0-9670
8
0-8953
31
0-9283
19
0-9709
7
0-8976
30
0-9314
18
0-9749
6
0-9001
29
0-9347
17
0-9790
5
0-9026
28
0-9380
16
0-9031
4
0-9052
27
0-9414
15
0-9873 | 3
0-9078
26
0-9449
14
0-9915
2
0-9106
25
0-9484
13
0-9959 1
Carius.
TABLE SHOWING SPECIFIC GRAVITY CORRESPONDING TO DEGREES,
TWADDELL, BAUMti, AND BECK, FOR LIQUIDS HEAVIER THAN WATER.
2
Corresponding Sp. Gr.
O gj
Corresponding Sp. Gr.
Q} 05
j> g
"a !'
a g>
Twaddell.
Baume.
Beck.
Twaddell.
Baume.
Beck.
1-000
I'OOO
1-000
21
1-105
1-166
1-1409
1
1-005
1-007
1-0059
22
1-110
1-176
1-1486
2
1-010
1-014
1-0119
23
1-115
1-185
1-1565
3
1-015
1-020
1-0180
24
1-120
1-195
1-1644
4
1-020
1-028
1-0241
25
1-125
1-205
1-1724
5
1-025
1-034
1-0303
26
1-130
1-215
1-1806
6
1-030
1-041
1-0366
27
1-135
1-225
1-1888
7
1-035
1-049
1-0429
28
1-140
1-235
1-1972
8
1-040
1-057
1-0494
29
1-145
1-245
1-2057
9
1-045
1-064
1-0559
30
1-150
1-256
2143
10
1-050
1-072
1-0625
32
1-160
1-278
2319
11
1-055
1-080
1-0692
34
1-170
1-300
2500
12
1-060
1-088
1-0759
36
1-180
1-324
2680
13
1-065
1-096
1-0828
38
1-190
1-349
2879
14
1-070
1-104
1-0897
40
1-200
1-375
1-3077
15
1-075
1-113
1-0968
45
1-225
1-442
1-3600
16
1-080
1-121
1-1039
50
1-250
1-515
1-4167
17
1-085
1-130
1-1111
55
1-275
1-596
1-4783
18
1-090
1-138
1-1184
60
1-300
1-690
1-5454
19
1-095
1-147
1-1258
65
1-325
1-793
1-6190
20
1-100
1-157
1-1333
70
1-350
1-909
1-7000
406
THE BREWER'S ANALYST
BOILING POINT OF WATER UNDER DIFFERENT PRESSURES.
Pressure
in
Atmos-
pheres.
Temperature.
Pressure
in
Atmos-
pheres.
Temperature.
F.
C.
F.
C.
1
1-5
212-0
233-9
100-0
112-2
12
14
374-0
386-9
190-0
197-2
2
250-5
121-4
16
398-4
203-6
3
275-1
135-1
18 408-9
209-4
4
293-7
145-4
20 418-4
2147
5
307'5
153-1
25 439-3
226-3
6
320-3
160-2
30
457-1
236-2
7
3317
166-5
35
472-6
244-8
8
341-7
172-1
40
486-5
252-5
10
358-8
181-6
45
510-6
265-9
TEMPERATURE OF STEAM UNDER DIFFERENT PRESSURES.
Pressure per
Square Inch.
Temperature.
Pressure per
Square Inch.
Temperature.
F.
C.
F.
C:
Lbs.
o-o
212-0
lOO'O
Lbs.
55-3
302-9
150-4
0-3
213-1 100-6
60-3
307-5
153-0
2-3
219-6
104-2
65-3
312-0
155-5
4-3
225-3
107-4
70-3
316-1
157-8
6-3
230-6
110-3
75-3
320-2
160-1
8-3
235-5
113-0
80-3
324-1
162-2
10-3
240-1
115-6
85-3
327-9
164-4
15-3
250-4
121-3
95-3
334-6
167-0
20'3
259-3 126-2
105-3
341-1
171-7
25-3
267-3 1307
115-3
347-2
175-1
30-3
274-4
134-6
125-3
352-9
178-2
35-3
281-0
138-3
145-3
363-4
184-1
40-3
287-1
141-7
165-3
372-9
189-4
45-3
2927
144-8
185-3
3817
194-2
50-3
298-0
1477
235-3
401-1
205-0
INDEX
Abbe condenser, 327, 330.
Achroo-dextrins, 63, 72.
Acid, acetic, analysis, 148.
table, 146.
value, 251.
amido, 85, 86, 87, 88.
aspartic, 85, 87.
citric, 146.
decinormal, 134.
diamido-caproic, 88.
diaraido- valeric, 88.
four-times normal, 134.
glutamic, 85, 87.
glutaminic, 85, 88.
hydrochloric, analysis, 147.
percentage table, 402.
table, 146.
hydroxy-caproic, 86.
nitric, analysis, 148.
percentage table, 403,
table, 146.
normal, 130.
oxalic, 132, 146.
rosolic, 126.
saccharic, 73.
sulphuric, analysis, 147.
normal, 130.
percentage table, 401.
table, 146.
tartaric, 146.
ulmic, 73.
Acidity, beer, 250.
malt, 201.
wort, 215.
Acids and bases, water analysis,
bisulphite analysis, 187.
Acrospire, 194.
Adjustment, microscope, 327.
Aerial fungi, 354.
hyphse, 342.
organisms, 351, 353, 354,368.
Aeroscope, 351.
Ailanthus glandulosa, 101.
Air-bath, 27.
Albumin, 82.
alkali, 83.
175.
Albumin, egg, 82.
plant, 83.
serum, 82.
Albuminate, 83.
Albuminoid ammonia in water, 168,
281.
Albuminoids, 61, 81. See also Pro-
teids.
barley analysis, 236.
beer analysis, 253.
malt analysis, 207, 208, 209.
rootlets analysis, 269.
raw-grain analysis, 232.
wort analysis, 215.
Albumins, 90.
Alcohol in beer, table, 250.
Alcoholmeter, 247.
Aldose, 62.
Aleurone cells, 113.
Alkali-albumin, 83.
decinormal, 134.
four-times normal, 134.
normal, 133.
percentage table, 404.
Alkalimetry, 124.
Alkaline earths, analysis, 146.
solutions, analysis, 152.
tarteite solution, 141.
Alkalinity, water analysis, 162.
Alkalies, analysis, 146.
Amber malt, 310, 311.
Amides, 84.
Amido-acetic acid, 88.
caproic acid, 85.
glutaric acid, 87.
succinic acid, 87.
succinamide, 86.
Ammonia, albuminoid, 168, 281.
analysis, 151.
carbonate, 146.
dilute, 139.
molybdate, 140.
percentage table, 405.
removal from water, 139.
standard, 138.
table, 146.
407
408
INDEX
Amylan, 62, 63, 80.
Araylo-cellulose, 63.
dextrins, 63, 72.
hydrolysts, 94.
Amyloins. See Mai to- dextrins.
Amylomyces Rouxii, 102.
Analyser, 48, 50.
Analysis, acetic acid, 148.
alkaline earths, 146.
solutions, 152.
ammonia, 151.
barley, 234.
caustic soda, 152.
glucose, 265.
hydrochloric acid, 147.
hops, 236.
malt, 189.
amber, 233.
black, 233.
brown, 233.
crystal, 233.
rootlets, 269.
wort, 212.
nitric acid, 148.
qualitative, 1.
quantitative, 1.
raw grain, 224, 233.
sodic carbonate, 151.
sugar, caramel, 268.
glucose, 265.
invert, 258.
raw, 265.
syrups, 268.
sulphites, 189.
sulphuric acid, 147.
typical, 379, 384, 385.
Anti-albumin, 99.
deutero-albumose, 100.
group, 99.
Antimonial mirror, 274.
Anti-peptone, 100.
Aperture, microscope, 327.
Apochromatic lenses, 329.
Apparatus, cleaning, 8.
sterilising, 365.
Appendix A, typical analyses, 379.
B, tables and factors, 394.
Arabinoxylan, 113.
Archimedes' principle, 29.
Argentic nitrate, 137.
Arginine, 85, 88.
Aribinose, 62, 63.
Armstrong, hydrolysis, 63, 94.
hydrolysts, 93, 94.
mutarotation, 54.
Arrowroot starch, 66, 69.
Arsenic, 270.
acids, 277.
beer, 270, 272, 276.
caramel, 277.
detection by Marsh - Berzelius
apparatus, 277.
Arsenic, fuel, 270.
hops, 271, 277.
malt, 270, 277.
Marsh test, 273.
Marsh-Berzelius test, 275.
mirrors, 272, 273, 278.
preservation of mirrors, 278.
reagents, 277.
Reinsch test, 272.
Royal Commission on, 270.
standard mirrors, 278.
sugar, 272, 277.
tests, 272.
Tyrer-Marsh apparatus, 274.
wort, 272.
yeast, 277.
zinc, 277.
Ascomycetes, 339, 345.
Ascospore formation, 358, 359.
Ash. See Mineral Matter.
Asparagine, 86.
Aspartic acid, 85, 87.
Aspergillus, 115.
fumigatus, 338.
glaucus, 340, 346.
niger, 115, 346.
nidulans, 346.
oryzce, 102, 110.
Atkinson, Aspergillus oryzce, 110.
Atmospheric organisms, 295, 354,
369.
Autoclave, 366.
Bacillus, hay, 332, 335.
leptothrix, 332, 336.
subtilis, 332, 335.
ulna, 332, 336.
Bacteria, 331.
aceti, 332, 333.
amylobacter, 332, 335.
butyricum, 332, 334.
cilium, 331.
colostridium, 335.
counting colonies, 371.
De Bary on, 331.
desmo, 332.
diastase, 102.
distinction from yeast, 331.
flagella, 331.
lactic, 332, 334.
locomotion, 331.
inegatherium, 115.
mesentericus vulgaris, 102.
micro, 332.
micrococcus, 332.
Pasteur ianum, 332, 333.
sarcina, 332.
spiro, 332.
staining, 349.
termo, 102, 332, 334.
water, 294.
INDEX
409
Bacteria, wort, 334.
xylinum, 332, 333.
Bailey, colour of beer and malt, 37.
malt extract, pounds per quarter
(table), 397.
percentage matters soluble in cold
water (table), 399.
wort sterilisation, 295.
Bailey and Ford's patent, 65.
Baker, extract raw grain, 230.
Balances, 15.
Balling saccharometer, 32.
Balsam, Canada, refractive index, 48.
Baric carbonate, 146.
hydrate, 146.
Barley, aleurone cells, 113.
Chevallier Chilian, 298.
Danubian, 308.
enzymes, 96.
germinator, 235.
Barley analysis, 234, 297-
acidity, 299.
defective corns, 234.
endosperm, 235.
extraneous matter, 234.
mineral matter, 236, 299.
moisture, 236, 300.
oil, 236.
physical examination, 300.
proteids, 236, 298.
starch, 236, 298.
steely corns, 235.
vegetative energy and capacity,
236.
weight, 235, 297.
Bases and acids, water analysis,
175.
bisulphite analysis, 187.
Bates hydrometer, 31.
Bath, water, 25.
Baume hydrometer, 31.
Becamp, invertase, 114.
Becher, micro-organisms in barley,
309.
Beer, gum in, 81.
malto-dextrins, 253.
micro-organisms in, 35.
viscosity, 310.
Beer analysis, acidity, 250.
alcohol, 249, 250.
biological examination, 376.
brilliancy, 257.
colour, 253.
distillation process, 245.
dry extract, 249.
iron, 253.
mineral matter, 253.
opticity, 252.
original gravity, 244, 247.
present gravity, 247-
proteids, 253.
salicylic acid, 253.
Beet sugar, 318.
Behrens, organisms and mould in
hops, 316.
Bermuda arrowroot starch, 68.
Bernard, invertase in animals, 115.
Berthelot, precipitation of invertase,
114.
Beta vulgaris, 101.
Bibra, Von, proteids of barley. 90
Kinks burette, 20.
Biological examination, beer 376
hops, 316, 374.
malt, 373, 384.
water, 294, 369.
wort, 374.
yeast, 375.
survey of brewery, 368.
Bioses, 114.
Bi-rotation, 54.
Bisulphite of lime, 296.
composition, 392.
analysis, 182.
acids and bases, 187.
calcic sulphite, 189.
chlorine, 185.
hyposulphites, 186.
iron, 186.
lime, 185.
magnesia, 185.
potassic sulphite, 189.
specific gravity, 182.
sulphuric acid, 182.
sulphurous acid, 182.
Bite of malt, 308.
Bituminous coal, 382.
Biuret reaction, 89.
Black malt, 310.
Blending malt, 302.
Blowpipe, 4.
foot-bellows, 5.
Boake Roberts, kalium - metabisul-
phite, 297, 392.
Boby screen, 190.
Bottcher moist chamber, 356.
Bottle, specific gravity, 33.
Bourguelot, diastase, 101, 110.
Boiler scale, 381.
Boiling tubes, 10.
Borer for corks, 6.
Brefeld, ascospores, 358.
spores, Bacillus subtilis, 335.
Brewers' grains, 391.
Brewery, biological survey, 368.
organisms, 369.
Brewing, starches employed, 72.
water manipulation, 290.
Briant, extract of malt, 198.
Brilliancy of beer, 257.
British gum, 68, 72.
Brown, A., Bacillus subtilis, 335.
Bacterium aceti, 333.
xylinum, 334.
410
INDEX
Brown and Escomb, dissolution of
starch cell wall, 113.
Brown and Heron, laws of diastatic
action, 104.
soluble matters in malt, 203.
solution factor, 58.
viscosity of starch paste, 70.
Brown, H., forcing tray, 376.
Brown malt, 310.
Brown and Millar, malto-dextrins,
79.
Brown and Morris, cytase in malt,
111, 113.
diastase in seeds, 101.
diastatic action, 107, 108.
dissolution of starch cell wall, 112.
soluble starch, 71, 72, 144.
invertase in malt, 115.
maltose production, 217.
reducing power of maltose, 78.
starch formula, 65.
metamorphosis, 66.
Brown, Morris, and Millar, opticity
of carbohydrates, 57.
opticity of starch, 71.
reducing values of maltose, 401.
of sugars, 400.
solution factors, 60.
of maltose, 58.
of starch conversion products,
59.
Buchner, researches in fermentation,
119, 122.
Budding fungi, 348.
Bunseu burner, 2.
sulphurous acid analysis, 150.
Burette, 20.
Burner, Bunsen, 2.
methylated spirit, 3.
Burroughs, Wellcome & Co., Tabloid,
297.
Burton-on-Trent water, 287.
Bynedestin, 92.
Bynin, 92.
Calcic chloride, 20. 293.
hydrate (table), 146.
levulosate, 75.
oxide, 146.
Calibration of thermometer, 11.
Canada balsam, refractive index,
48.
Cane-sugar, 63, 76.
action of zymase on, 120.
Egyptian, 318.
fermentation, 77.
hydrolysis, 115.
action of invertase on, 115.
invert in, 262.
jaggery, 318.
molecular weight, 263.
molecule, 319.
Cane-sugar, opticity, 57.
Penang, 318.
polarimetric estimation, 54, 56.
properties, 76.
speed of inversion, 118.
Caramel, 73, 76, 325.
arsenic, 277.
colour, 268.
dextrinous, 390.
fluid, 390.
liquorice, 325.
opticity, 268.
quantitative tests, 269.
Caramel analysis, 268.
colouring power, 268.
deportment with beer and proof
spirit, 269.
fermentability, 269.
Carbohydrates, 61.
cupric oxide reducing power, 59,
60.
Emil Fischer on, 61.
inert, 320.
occurrence, 62.
opticity, 57.
solution factors, 59, 60.
Car ica papaya, 97.
Carius's table, 151.
Casein, 83.
Caustic potash, composition, 393.
percentage table, 404.
table, 146.
soda, composition, 393.
percentage table, 404.
table, 146.
Celluloses, 62, 63.
purification, 64.
sources, 64.
Centigrade scale, 13.
Centrifuge, 34.
Cereals, composition, 383.
starch in, 237.
Chamber, moist, 370.
Charcoal, composition, 381.
Chemical tests, delicacy of, 162, 174.
Chemicals for volumetric analysis,
145.
Chevalier Chilian barley, 298.
Chlorine in water, 160, 284.
Cholera vibrio, 102, 115.
Chondrometer, 191.
Cilium of bacteria, 331.
Citric acid, 146.
Cleaning apparatus, 8.
Coal, bituminous, 382.
composition, 382.
Cochineal solution, 125.
Coffee mill, malt grinding, 195.
sugar, 141.
Cohn, Bacillus ulna, 336.
Coke, composition, 382.
Coldew, barley germinator, 235.
INDEX
411
Collar, correction, 329.
Colonies, counting, 371.
sprouting, 339.
Colour estimation, beer, 253.
caramel, 268.
glucose, 260.
invert sugar, 260.
water, 155.
wort, 204.
Colour malts, 233, 310.
Colutnella, 343.
Condenser, Abbe, 327, 330.
Copper in water, 174.
sulphate solution, 141.
wort analysis, 219.
Corks, boring, 6.
Corn-sampler, 190.
Corns, defective, 190.
steely, 191, 234, 235.
Correction collar, 329.
Cotton-wool, sterilisation, 365.
Crucible tongs, 10.
Crystal malt, 310.
optic axis of, 46.
Culms, malt, 269.
Cultivations, pure, 368.
Culture, plate, 369.
Cupric oxide reducing power, carbo-
hydrates, 59, 60.
dextrose, 74, 266.
laevulose, 75.
maltose, 60, 266, 401.
sugars, 400.
wort, 201, 213.
Cylinders, graduated, 22.
Cytase, 96, 102, 111.
activity, 113.
hydrolytic action, 113.
separation from malt, 113.
Dafert, drying starch, 68.
Dafert and Kreusler, starch and
iodine, 71.
Danubian barley malt, 308.
De Bary, bacteria, 331.
De Chaumont, tides and well waters,
285.
Delicacy of chemical tests, 162, 174.
Decinormal acid, 134.
alkali, 134.
Defective corns, 234.
Density, 29.
Desiccator, 19.
Deuteroproteose, 92, 99.
Dextrin, 62, 63, 68, 72.
molecule, 79.
opticity, 57.
polarimetric estimation, 56.
properties, 72.
stable, 79, 80.
types, 62, 63, 72.
Dextrin-maltose, 324.
Dextrin, stock-ale, 218.
Dextro-rotatory substances, 49.
Dextrose, alcohol from, 74.
cupric oxide reducing power, 74,
266.
fermentation of solutions, 73.
from caue-sugar, 75.
hydrazone, 74.
invert sugar, 75.
muta-rotation, 74.
opticity, 74, 266.
table, 57.
osazone, 74.
preparation, 73.
quantitative determination, 73.
reduction of metallic oxides, 73.
sweetness, 73.
Diamido-caproic acid, 88.
valeric acid, 88.
Diaphanoscope, 191.
Diaphragm, iris, 327, 330.
Diastase, 72, 86, 94, 101.
absolute energy, 107.
action of heat on, 105.
action in different media, 106.
activity, 103.
bacterial, 102.
laws of action, 104.
liquefying function, 106.
malt, 101, 103, 107, 112.
plant, 102.
preparation from malt, 103.
saccharifying function, 105.
secretion, 102.
translocation, 98, 102.
Diastatic enzymes, 96.
power, 102, 107, 209, 231, 306,
307.
Dilution, fractional, 354.
Disaccharides, 63, 76.
Distillation, 29.
process, beer, 245.
Donath, invertase, 114.
Double-image prism, 46.
refraction, 46.
Dringe and Fage's saccharometer, 32.
Dry hopping, 340.
objectives, 328.
Dublin water, 288.
Dubrunfaut, diastase, 107.
maltose, 78.
Duclaux, moulds and diastase, 101.
Dupasquier, iodine and sulphurous
acid reaction, 150.
Dust, malt, 385.
Earths, alkaline, analysis, 146.
Edestin, 91.
Edinburgh water, 288.
Effront, enzymes, 95.
function of diastase, 106.
412
INDEX
Effront and Fernback, asparagine
and diastase, 86.
Egg albumin, 82.
Enrich, starch transformation, 104.
Einulsin, 97.
Endosperm, 235.
Engel, ascospores, 358.
Enzymes, 61, 93, 94.
action of heat on, 95.
barley, 96.
composition, 387.
diastase, 96.
glucosidal, 97.
groups, 96.
hydrolytic action, 96.
intestinal 96.
inverting, 96.
kephir, 96.
malt, 96.
pectin, 96.
proteolytic, 96, 98.
yeast, 96.
Epsom salt, 381.
Erythro-dextrins, 63, 72.
Eurotium aspergillus glaucus, 346.
niger, 346.
Evaporation of liquids, 25.
Extract of malt, determination, 196,
198, 200.
full theoretical, 200.
pounds per quarter (table), 397.
Extraordinary ray, 48.
Eye-piece of microscope, 328.
Fahrenheit's scale, 14.
Farinator, 191.
Fat-extracting apparatus, 226.
Fehling's solution, 140.
test, 140, 142, 213, 214.
Ferment, taka, 115.
viscous, 332.
Fermentation, Buchner's researches,
119.
by yeast, 116.
of levulose, 75.
processes, 94.
Ferments, unorganised, 93.
Fernback, action of diastase, 104.
acidity of mash, 107.
Fernback and Hubert, proteolytic
enzyme, 98.
Ferrous thiocyanate, 126.
Fibrin, 82.
Field, alcoholmeter, 247.
Film formation, 360.
Filter papers, 28.
Filters, 23.
in water analysis, 155.
Fine adjustment of microscope, 327.
Fischer, Emil, carbohydrates, 61.
invertase, 115.
yeast enzyme, 110.
Flagella of bacteria, 331.
Flaked maize, 386.
rice, 386.
Flame colorations, wire for, 9.
Flasks, measuring, 22.
Pasteur, 355, 357.
Tyrer-Marsh, 274.
Foot-bellows, blow-pipe, 5.
Forcing tray, 367.
test, 376, 378.
Ford and Guthrie, moisture in malt,
202.
Forschammer's oxygen process, 138,
171, 282.
Four-times normal acid and alkali,
134.
Fractional dilution, 354.
Frankland, aerial organisms, 353.
classification of water, 281.
Fresenius, test for nitrous acid, 167.
Fresnel, polarisation of light, 44.
Frew, extract of malt, 199.
Fuel, arsenic in, 270.
Fungi, 336.
aerial, 354.
budding, 348.
hops, 316.
orders, 340.
Funnel, 23.
Furfural, 62, 63.
Fusarium, 115.
Galactose, 62.
Galactoxylan, 62, 63, 81.
Gallisin, 73.
in glucose, 267.
Gait, table of starches, 69.
Gaultier de Clanbry, soluble starch,
71.
Gay-Lussac, boiling point, 13.
burette, 20.
Gelatine meat broth, 353.
solution, 145.
Gelatinisation of starch, 70.
temperatures of starch, 387.
Gelatinised starch, 172.
Germination of the Graminese, 66,
111.
Germinator, Coldew's, 235.
Germs in water, 294.
Giles and Shearer, sulphurous acid,
151.
Gladstone and Tribe, nitric acid in
water, 165, 166.
Glass, bending, 4.
cutting, 3.
heating, 9.
Gliadin, 90.
Gloubulins, 90.
Glucase, 96, 109.
and maltose, 110, 266.
effects of temperature on, 111.
INDEX
413
Glucase extraction, 110.
in maize, 109.
in malt, 109.
in nature, 110.
Glucosan, 73.
Glucosazone, 74, 77.
Glucose, 78, 96.
Glucose analysis, 265, 323.
colour, 260.
composition, 389.
gallisin, 267.
in maize, 111.
opticity, 265.
Glucosidal enzymes, 97.
Glucosides, 73.
Glutamic acid, 85, 87.
Glutaminic acid, 85, 88.
Glutanin, 90.
Gluten, 83.
casein, 90.
fibrin, 90.
Glutinous precipitates, 64.
Glycocoll, 88.
Graduated cylinders, 22.
Graduation of thermometers, 11.
Graham, acetic acid value, 251.
distillation process, 245.
Grains, spent, 391, 392.
Graniinese, germination of, 66, 111.
Granules, starch, 67, 68.
Granulose, 63, 70.
solution, 70.
Gravimetric estimations, 1.
Green, enzyme of date-seed, 113.
Greiss, test for nitric acid in water,
167.
Greissmayer, types of dextrin, 72.
Griffin and tire, standard test
solutions, 127.
Grits, 224.
maize, 312, 386.
rice, 386.
Guibort, microscopy of the starches,
68.
Guinness Research Laboratories, 206,
228.
Gum, 68, 72, 81.
Gun-cotton, 64.
Gunning, estimation of proteids, 206.
invertase in yeast, 114.
Giiss, hemicellulose, 113.
Gypsum, 381.
Haberland, constituents of hops, 314.
Hsematimeter, 355.
Half-shadow polarimeter, 54.
degrees, 54.
Hansen, aerial yeasts, 354.
ascospores, 358.
Bacterium, Pasteurianum, 333.
counting colonies, 372.
diastase in sap, 101.
Hansen, film formation, 360.
Mucor mucedo, 344.
organisms in water, 295.
pure cultivations, 363.
saccharomyces, 358.
saccharomycetes, 357.
solid cultivating media, 356.
wort bacteria, 334.
yeast cultivation, 355.
Harcourt's law, 321.
Hard water, 286.
Hardness, permanent, 287.
temporary, 287.
Hay bacillus, 332, 335.
Hayduck, tannin in hops, 241.
zymase, 122.
Hearson's incubating apparatus, 367.
Hemicelluloses, 62, 63, 113.
Hemi-group, 99.
Heron, ash of sugars, 259.
colour of wort, 204.
decolorising beer, 252.
malt analysis, 197.
malt extract, 198.
malt-wort analysis, 213.
opticity of wort, 302.
resins in hops, 238.
tannin in hops, 238, 241.
Heteroproteose, 92, 99.
Hexoses, 62, 73.
phenyl-hydrazine reaction, 74.
Histidine, 85, 88.
Hoffmann, acetic acid value, 251.
distillation process, 245.
Holm and Poulsen, analysis of yeast,
360.
Homogeneous objectives, 329.
Hop, cold-stored, 314.
deterioration, 315.
fungi, 316.
lupulin, 313.
mould, 316, 375.
old, 315.
old olds, 314.
organisms, 316, 374.
seeds, 313.
strig, 313.
sulphuring, 315.
yearlings, 314.
Hop analysis, 236.
arsenic, 271, 277.
biological examination, 316, 374.
extraneous matters, 236.
moisture, 242, 315.
resins, 237, 315.
sulphur, 242, 315.
tannin, 238, 315.
Hopping, dry, 340.
Hordein, 90, 91.
Hueppe, aerial organisms, 352.
Hydrates, 61.
Hydrazone, 74.
414
INDEX
Hydrochloric acid, analysis, 147.
percentage table, 402.
table, 146.
Hydrolysis, 63, 94, 115.
Hydrolysts, 93, 94.
Hydrometer, 31. See also Saccharo-
meter.
Bates, 31.
Baume, 31.
Sykes, 31.
Twaddell, 31.
Hydroxy-caproic acid, 86.
Hyphse, aerial, 342.
Hyphomycetes, 336, 339.
Hypodermi, 341.
Iceland spar, 45.
Ignition of precipitates, 28.
tubes, 5.
Immersion objectives, 328.
Incubating apparatus, 366, 367.
Indicators, 124.
cochineal, 125.
ferrous thiocyanate, 126.
iodine, 126.
indigo, 136.
litmus, 124.
methyl-orange, 125.
phenacetolin, 125.
phenol-phthalein 125.
rosolic acid, 126.
Indigo process, Marx, 165.
solution, 136, 145.
Inland Revenue, acidity of beer, 250.
Interpretation of the results of ana-
lysisbarley, beer, hops, malt,
water, wort, etc., 279-325.
Inulin, 62, 63.
Inversion of sugar, 118, 318, 321.
Invert-sugar analysis, 258.
acidity, 261.
cane-sugar, 262.
colour, 260.
dry extract, 259.
extract per cwt. , 258.
iron, 260.
mineral matter, 258.
moisture, 259.
opticity, 263.
proteids, 260.
unfermen table matter, 263.
Invertan series, 117.
Invertase, 77, 96, 114, 115.
opticity, 117.
separation from solutions, 117.
sugar inversion by, 321.
yeast, 115.
Iodine, chemically pure, 135.
decinormal, 135.
reaction with starch, 71.
solution, 126.
Iris diaphragm, 327, 330.
Iron, bisulphite of lime, 186.
estimation in water, 161.
in beer, 253.
in sugar, 260.
solution, 137.
Isochlors, 284.
Isomers, 62.
Jaggery cane-sugar, 318.
Jansen's yeast cell, 347.
Jorgensen, micro-organisms of fer-
mentation, 341.
saccharomyces, 361.
Kalium metabisulphite, 297.
composition, 392.
Kanite, 381.
Keen , distilling apparatus, 29.
Kephir enzyme, 96.
Ketose, 62.
Kieselguhr, 118.
Kirchoff, barley albumin, 101.
glucose, 323.
Kjeldahl, diastase in seeds, 101.
diastatic power, 108, 306.
estimation of maltose, 78.
proteids, 205.
function of diastase, 106.
invertase in malt, 115.
proteids in invert sugar, 260.
Koch, biological examination of water,
369.
aerial organisms, 352.
Koji yeast, 102.
Kossmann and Kranch, diastase in
vegetable substances, 101.
Kreusler, barley albumin, 91.
Kiihne, enzymes, 93.
Lactic acid, 334.
bacteria, 332, 334.
Lactose, 63.
opticity, 57.
Lsevo-rotatory substances, 49.
Lamp, spirit, 3.
Landolt, optical rotation of organic
substances, 49.
Lange, zymase, 122.
Laurent, plate, 50.
polarimeter, 49, 50.
polarimetric degree, 54.
Law, Harcourt's, 321.
Law of definite relation, 108.
of proportionality, 108.
Laaynscki, proteolytic enzyme, 98.
Lead, estimation in water, 174.
Legumin, 83.
Lenses, microscopical, 328, 329.
Leucine, 85.
Leuconostoc mesenteroides, 115.
Leucosin, 91, 92, 95.
Leuwenhoek, starch granules, 68.
INDEX
415
Levulosate, calcic, 75.
Levulose, 62, 75, 76.
crystals, 75.
cupric oxide reducing power, 75.
fermentation, 75.
opticity, 57, 75.
osazone. 76.
preparation, 75.
Lichtheim, mucors, 345.
Liebig, distilling apparatus, 29.
sulphuring hop bines, 316.
Light, Tyndall's lectures on, 44.
polarisation, 39.
theory, 41.
Lime, bisulphite. See Bisulphite
of Lime.
Ling, diastatic action, 107.
soluble matters in malt, 203.
Lintner, diastase, 103.
diastatic power, 108, 210, 306.
process, 144.
enzyme, 94.
gum in beer, 81.
opticity of starch, 71.
process, 307.
Lippich polarimeter, 49, 53.
Liquids, evaporation of, 25.
Lisle, Observations in Husbandry , 192.
Litmus papers, 125.
solution, 124.
Lobry de Bruyn, solution weights
of sugars, 58.
London water, 289.
Long half-shadow polarimeter, 49.
Lovibond tintometer, 36. See also
under Colour.
Lb'wenthal, tannin, 238.
Lupulin, hop, 313.
Lysatine, 85, 88.
Lysine, 85, 88.
Macfadyen and Morris, fermentation,
122.
Magnesia, 146.
estimation in water, 159.
mixture, 140.
solution, 140.
Magnifying power of microscope, 330.
Maize, composition, 383, 386.
flaked, 386.
glucase in, 109.
glucose in, 111.
granulated, 312, 386.
grits, 312, 386.
prepared, 225.
starch, 69.
wort, 224.
Malt, acrospire, 194.
bite of, 308.
blending, 302.
colour varieties, 233, 310.
cytase, 113.
Malt, defective corns, 190.
diaphanoscope, 191.
diastase, 101, 103, 107.
diastatic power, 209, 305, 307.
drying, 270.
dust, 385.
enzymes, 96.
extract. See Extract of Malt.
farinator, 191.
forced and unforced, 304.
glazing, 310.
glucase in, 109.
green, 211.
grinding, 195.
law of relative diastatic power, 306.
micro-organisms in, 309.
modification, 200.
proteolytic enzyme, 98.
Seek mill, 195.
sinker test, 192.
slack, 388.
specific gravity, 193.
sugar, 63.
typical analyses, 384, 385.
Malt analysis, 189.
acidity, 201, 303.
amber, 310, 311.
arsenic, 270, 277.
biological examination, 309, 373,
384.
black, 310.
brown, 310.
colour estimation, 37.
value, 234, 305, 311.
composition, 285.
crystal, 810.
culms or rootlets, 269.
diastatic power, 209, 305, 307.
dry extract, 196.
extract, 103, 198, 200, 301, 397.
extraneous matters, 190.
matters soluble in cold water, 203,
303.
mineral matter, 204.
moisture, 201, 308.
opticity of wort, 201.
physical examination, 308.
proteids, 91, 100, 205, 207, 209,
307.
ready - formed soluble carbo-hy-
drates, 204.
rootlets or culms, 269, 392.
saccharification period, 197, 301.
specific gravity, 10 per cent, wort,
193.
steely corns, 191.
weight, 191, 301.
Maltase, 109.
Malting, cytase, 112.
diastase, 112.
sulphur, 270.
test of efficiency, 304.
416
INDEX
Malto-dextrins, 63, 72, 79, 324.
beer, 253.
wort, 221.
Maltose, 63, 74, 77, 78, 96.
action of glucase on, 110.
conversion from starch, 71.
cupric oxide reducing power, 60,
266, 401.
discovery, 78.
estimation, 78.
in glucose, 266.
opticity, 57, 78, 266.
polarimetric estimation, 56.
preparation, 78.
solution factor, 58.
Manley, alcoholmeter, 247.
Mannose, 62.
Marsh test for arsenic, 273.
Marsh- Berzelius apparatus, 277.
test for arsenic, 275.
Marx indigo process, 165.
Mash, starch in, 197.
wort opticity, 201, 302.
Mash- tun wort analysis, 218.
Matthews and Lott, Bacillus subtilis,
335.
Mayer, invertase, 114.
Meacham, specific gravity of malt, 193.
Measuring flasks, 22.
Meat-broth, gelatine, 353.
Melibose, 80.
Meniscus, 21.
Mercury process, estimation of
nitrogen, 165.
Metabisulphites, 297.
Methylated spirit burner, 3.
Methyl-orange solution, 125.
Mierococcus agilis, 331.
Micro-organisms, counting colonies,
371.
cultivation, 353.
in malt, 309.
in water, 294.
separation from beer, 35.
Microscope, 326.
Abbe condenser, 327, 330.
aperture, 327.
apochromatic lenses, 329.
coarse adjustment, 327.
correction collar, 329.
dry objectives, 328.
eye-piece, 328.
fine adjustment, 327.
homogeneous objectives, 329.
immersion objectives, 328.
iris diaphragm, 327, 330.
lenses, 328.
magnifying power, 330.
measurements, 327, 331.
mirror, 327.
nose-piece, 326.
objectives, 326, 328, 329.
Mild ale, water for, 179, 290.
Mildew, 337.
Milk sugar, 63.
Mill, coffee, 195.
Seek, 195.
Millon's reagent, 89.
Mineral matter, barley, 236.
beer, 253.
malt, 204.
raw-grain, 232.
sugar, 258, 259.
wort, 216.
Mirror, antimonial, 274.
arsenical, 273.
standards, 273, 278.
microscope, 327.
Miquel, aerial organisms, 351, 353.
Mitscherlich, invertase, 114.
Modification of malt, 200.
Mohr, burette, 20.
decinormal sodic thiosulphate, 136.
iodine reaction, 150.
standard solutions, 127.
Moist chamber, 370.
Moisture, barley, 236, 300.
colour malts, 311.
hops, 242, 315.
malt, 201, 308.
sugar, 259.
Molecule, starch, 79.
Monilia Candida, 77, 115, 340, 349.
Monosulphite of lime, 393.
Moritz and Morris, malto-dextrins,
221.
soluble carbohydrates in malt, 304.
Morris, aerial organisms, 354.
enzyme of yeast, 110.
Hanson's experiments, 355.
malto-dextrins, beer, 253.
soluble carbohydrates in malt, 203.
unfermentable residue of beer, 114.
Mother of vinegar, 333.
Mould, hops, 316, 375.
yeast, 375.
Moulds, 336.
staining, 349.
Mucedin, 90.
Mucor aspergillus, 345.
circinelloides, 345.
erectus, 345.
fusiger, 345.
macrocarpus, 345.
mucedo, 339, 340, 341.
phycomyces, 345.
racemosus, 115, 338, 344.
sjrinosus, 345.
stolonifer, 345.
Mucors, 102.
Mulder, diastase, 101.
estimation of tannin, 238.
invertase, 114.
proteids of barley, 90.
INDEX
417
Multipliers in volumetric analysis,
146, 394.
Munktell, filter papers, 28.
Musculus and Gruber, glucose, 109.
Mushroom, 337.
Muspratt,kalium-metabisulphite,297.
Muta-rotation, 54, 74.
Mycelium, 338, 341.
Mycoderma aceti, 333.
Myosins, 90.
Nsegeli, structure of starch granule, 70.
dextrin, 72.
fractional dilution, 354.
Nessler's solution, 139.
Nesslerising, 169.
Neubauer, estimation of tannin,
238, 241.
New River Company, albuminoid
ammonia in water, 168.
Nicol prism, 47.
Nitrates in water, 283.
Nitric acid analysis, 148.
normal, 132.
percentage table, 403.
table, 146.
water, 165, 166.
Nitro-cellulose, 64.
Nitrogenous bodies. See Proteids.
Normal solutions, 127.
Nucleus of yeast, 347.
Nutrient media, sterilisation, 365.
Nose-piece of microscope, 326.
Oat starch, 69.
wort, 224.
Oatmeal, composition, 383.
Objectives, microscope, 326.
dry, 328.
homogeneous, 329.
immersion, 328.
Observations in Husbandry. 192.
Oidium lactis, 340, 345.
Old Carlsberg Brewery, 357.
Old hops, 365.
Optic axis of crystal, 46.
Opticity, 49, 55, 57.
beer, 252.
cane-sugar, 57.
caramel, 268.
carbohydrates, 57.
dextrin, 57.
dextrose, 57, 74, 266.
glucose, 265.
invertase, 117.
invert sugar, 263.
levulose, 57, 75.
malt wort, 201, 302.
maltose, 57, 78, 266.
raffinose, 80.
starch, 71.
wort, 215.
Orcein, 81.
Ordinary ray, 48.
Organisms. See Micro-organisms.
Organic matter, water, 157, 168, 282.
Original gravity of beer, 244, 247.
Otomycosis, 338.
Otto, sulphuric acid table, 401.
Oxalic acid, normal, 132.
table, 146.
Oxide reducing power. See Cupric
Oxide Reducing Power.
Oxycelluloses, 62, 63, 65.
Oxygen process, 138, 171, 282.
Osazone, 74, 76, 78.
Osborne, diastase, 94, 95, 103.
proteids in barley, 90, 91.
in malt, 100.
Osborne and Campbell, proteids in
malt, 91.
O'Shaughnessy, decinormal thiosul-
phate solution, 136.
Osmosis, 116.
O'Sullivan, amylan, 80.
dextrin, 72.
diastase, 101, 102.
estimation of starch, 227.
extract from raw grain, 230.
invertase, 115, 117, 118.
maltose, 58, 60, 78.
raffinose, 80.
solution factor, 57.
spent grains, 391, 392.
yeast, 115.
yeast in fermentation, 319.
O'Sullivan and Tompson, sugar in-
version by invertase, 116.
Pale ale, dextrin percentage, 218.
water for, 289, 290.
Pancreatic emulsion, 95.
Parke's classification of waters, 286.
Paste, starch, 70.
Pasteur, aerial organisms, 353.
Bacterium aceti, 333.
butyricum, 335.
decomposition of sugar, 391.
fermentation, 119.
flask, 355, 357.
inoculation of nutrient media, 350.
lactic acid ferment, 334.
viscous ferment, 332.
Payen, starch paste, 70.
diastase, 103.
Payen and Piersoz, diastase, 101, 108.
Pea starch, 69.
Peat, composition, 383.
Pedioccus acidi lactici, 332.
Penang cane-sugar, 318.
Penicillium Duclauxii, 115.
glaucwn, 101, 115, 340, 346.
Pentoses, 62, 63.
Pepsine, 95.
27
418
INDEX
Peptones, 84, 99.
Percival, hops, 313.
Permanent hardness, 287.
Petit and Labourasse, proteolytic
enzyme, 98.
Petri, aerial organisms, 353.
counting colonies, 372.
steam steriliser. 366.
Phenacetolin solution, 125.
Phenol-phthalein solution, 125.
Phenyl - hydrazine, reaction with
hexoses, 74.
Phloroglucin, 81.
Phycomycetes, 341.
Physiology of foliage leaves, 66.
Pipettes, 21.
Plane polarisation, 42.
Plant albumin, 83.
Plants, diastase, 102.
Plate culture, 369.
Platinum foil, cleaning, 9.
wire, cleaning, 9.
mounting, 5.
Pneumomycosis, 338.
Polarimeter, 39, 47.
bi-rotation, 54.
decolorising solutions, 51.
estimation of cane-sugar, 54, 56.
of dextrin, 56.
of maltose, 56.
half-shadow, 54.
degree, 54.
Laurent, 49, 50.
Lippich, 49, 53.
Long, 49.
muta-rotation, 54.
observation tubes, 51.
opticity, 55.
Schmidt and Haensch, half- shadow,
49, 54.
Soleil, 49.
Ventzke-Scheibler, 49.
Polarisation of light, 39.
analysing instruments, 47.
by double refraction, 45.
by reflexion, 43.
by refraction, 41.
dextro-rotatory substances, 49.
FresnePs theory, 44.
laevo-rotatory substances, 49.
laws of, 43.
opticity, 49.
polarising angle, 43.
instruments, 47.
rectilinear, 42.
specific -rotatory power or opticity,
49.
Polariser, 48, 50.
Polarising angle, 43.
Polysaccharides, 63, 79.
Porcelain, heating, 9.
Porter, water for, 180.
Potash, composition, 393.
percentage table, 404.
table, 146.
Potash and Soda, estimation in water,
163.
Potassic bicarbonate, 146.
carbonate, 146.
composition, 393.
hydrate, 146.
iodide solution, 138.
nitrate, 136.
permanganate, alkaline, 140.
decinormal, 134.
thirtieth normal, 138.
sulphite, 297.
Potato starch, 69.
Prazmowski, Bacterium, bulyricum,
335.
Precipitates, drying, 27.
gelatinous, 24.
ignition, 28.
Present gravity of beer, 247.
Priming syrups, 268, 325, 389.
Prior, acidity of barley, 299.
of malt, 303.
of mash, 107.
Prism, double-image, 46.
Nicol, 47.
Proof spirit, 250.
Protective serum, 88.
Proteids, 61, 81.
action of proteolytic enzyme, 97.
ammonia evolved from, 89.
barley, 90, 236.
beer, 253.
biuret reaction, 89.
chemical reactions, 88.
cyanides from, 89.
estimation, 100.
groups, 89.
hydrolysis, 84.
insoluble, 92.
invert sugar, 260.
malt, 91, 100, 205, 207, 209,
307.
molecular constitution, 83.
molecules, 84.
Osborne's researches, 91.
products of proteolytic action,
99.
raw grain, 232.
soluble, 208.
wort, 215.
Proteo-hydrolysts, 94.
Proteolytic enzymes, 96, 98.
Proteoses, 84, 91, 99.
Protoplasm, living and dead, 347.
Protoproteoses, 92.
Ptomaines, 88.
Ptyalin, 95, 96.
Pure cultivations, 368.
yeast, 364.
INDEX
419
Qualitative analysis, 1.
Quantitative analysis, 1.
Quarts, Winchester, 154.
Raffinose, 63, 79, 80.
fermentation, 80.
opticity, 80.
Raoult, proteids, 84.
Raspail, starch granules, 68.
Raw-grain analysis, 224, 233, 312.
acidity, 232.
cupric oxide reducing power, 228.
extract per quarter, 229.
mineral matter, 232.
moisture, 232.
oil, 226.
proteids, 232.
starch, 227.
Raw-grain wort analysis, 218.
Raw sugar, 316.
analysis, 265.
composition, 388.
Ray, extraordinary, 48.
ordinary, 48.
Reagents, testing, 277.
Reaumur's scale, 14.
Rectilinear polarisation, 42.
Reducing power. See Cupric Oxide
Reducing Power.
Redwood, acetic acid value, 251.
distillation process, 245.
Reess, ascospores, 358.
cell juice, 346.
Refined sugar, 316.
Refraction, double, 46.
Reichert, thermostat, 27.
Reinsch, test for arsenic, 272.
Rendement of sugar, 317.
Reproduction, asexual, 338.
by fission, 339.
sexual, 343.
Resins, hop, 237, 315.
Resorcinol, 82.
Resting snores, 344.
Rice, 312.
composition, 383.
flaked, 386.
granulated, 312.
grits, 386.
prepared, 225.
starch, 69.
wort, 224.
Ritthausen, proteids in wheat, 90.
Roberts, diastatic power, 107.
enzymes, 93.
Rochelle salt, 141.
Rods, stirring, 6.
Rootlets, malt, 269, 392.
Rosolic acid solution, 126.
Rotatory power. See Opticity.
Royal Commission on Arsenic, 270.
Royal Microscopical Society, micro-
scopical measurements, 331.
Rubber stoppers, 7.
boring, 6.
Rudberg, boiling point, 13.
Rye, composition, 383.
starch, 69.
Saccharates, 77.
Saccharic acid, 73.
Saccharification, 104.
period, 197, 301.
Saccharines from starch, 323.
Saccharo -bacillus Pastorianus, 257.
Saccharometer, 31, 32. See also
Hydrometer.
Balling, 32.
Bring and Fage, 32.
Saccharomyces albicans, 349.
apiculatus, 115, 349, 356.
ceremsice, 348, 361, 363.
conglomerate, 362.
ellipsoideus, 348, 362.
exiguus, 362.
kefir, 349.
Ludwigie, 349.
minor, 362.
Pasteurianus, 348, 361, 362.
Saccharomycetes, 339, 346.
Saccharose, 63.
Saccharum, 318.
Sachs, enzyme of date-seed, 113.
text-book of botany, 341.
Sago, 66.
starch, 69.
Saki, 102.
Salicylic acid in beer, 253.
Saline residue, water, 156.
Salt, Epsom, 381.
Rochelle, 41.
Salting out albuminoids, 89.
Salts, calculation in water, 175.
for Wetter manipulation, 292.
Samples for water analysis, 154.
corn, 190.
Sarcina, 257, 332.
maxima, 332.
Sarcine, 88.
Scales of temperature, 1 3.
conversion, 14.
Schizomycetes, 331.
Schmidt and Haensch, polarimeter.
49, 54.
Schwacktiofer, micro-organisms in
water, 295.
Schwann, protoplasm, 350.
yeast, 114.
Screen, Boby, 190.
Sea salt in water, 284.
Seek mill, 195.
standard, 196.
grinding malt, 301.
420
INDEX
Secretion diastase, 102.
Seeds, hop, 313.
Serum albumin, 82.
protective, 88.
Sewage in streams, 280.
Seyler, invertase, 114.
Silica, estimation in water, 173.
Silver nitrate, 137.
Sinker test, 192.
Slack malt, 308.
Soda analysis, 152.
and potash, estimation in water,
163.
caustic, 393.
percentage table, 404.
table, 146.
Sodic bicarbonate, 146.
sulphite, 297.
carbonate analysis, 151.
normal, 133.
table, 146.
chloride, decinormal, 136.
estimation in water, 160.
cyanide, 89.
hydrate, 133, 146.
thiosulphate, 138.
Soleil polarimeter, 49.
Soluble starch, 63, 70, 71, 144.
Solution, alkaline tartrate, 70.
cochineal, 125.
copper sulphate, 141.
Fehling's, 140.
gelatine, 145.
iron, 137.
litmus, 139.
Nessler's, 139.
weight, 57.
Solutions, alkaline, 152.
normal, 127.
standard, 127. See also Standard
Solutions.
Soxhlet, fat-extracting apparatus, 226.
maltose, 78.
Spar, Iceland, 45.
Specific gravity, 29.
bottle, 33.
liquids heavier than water, 405.
pounds per barrel, 32.
rotatory power. See Opticity.
Spent grains, composition, 391, 392.
extraction of sugar from, 65.
Spirillum tenue, 332, 336.
undula, 336.
Spirit indication, 245, 246.
lamp, 3.
proof, 250.
Sporangium, 338.
Spores, 331, 337.
growth of sporangium, 342.
resting, 344.
yeast, 358.
Spoliation, 342.
Sprouting colonies, 339.
Staining, bacteria, moulds and yeast,
349.
Standard and other solutions, 127.
acid and alkali, decinormal, 134.
four-times normal, 134.
hydrochloric, normal, 133.
nitric, normal, 132.
oxalic, normal, 132.
sulphuric, normal, 130.
ammonia, 138.
dilute, 139.
molybdate, 140.
Argentic nitrate, 137.
Fehling's, 140.
gelatine, 145.
indigo, 136, 145.
iodine, decinormal, 135.
iron, 137.
magnesia, 140.
Nessler's, 139.
potassic iodide, 138.
nitrate, 136.
potassic permanganate, 134, 138,
140, 144.
sodic carbonate, normal, 133.
chloride, decinormal, 136.
hydrate, normal, 133, 146.
thiosulphate, 138.
decinormal, 135.
soluble starch, 63, 70, 71, 144.
Standardisation, 141.
Starch, 62, 63, 67, 69.
arrowroot, 69.
barley, 69, 236.
brewing, 72.
bursting granules, 70.
conversion, 71.
drying, 68.
estimation in cereals, 227.
flaked and granulated maize and
rice, 312.
formula, 65.
gelatinisation of, 70.
temperatures, 387.
gelatinised, 172.
granules, 67, 68.
hydrolysis, 79.
iodine reaction, 71.
maize, 69.
mash, 197.
metamorphosis, 66.
microscopic character of granules,
67, 69.
moisture, 68.
molecular weight, 72.
molecules, 79.
oat, 69.
opticity, 71.
paste, 70.
pea, 69.
potato, 69.
INDEX
421
Starch, properties, 68.
purification, 67.
rice, 69.
rye, 69.
saccharines, 323.
sago, 69.
soluble, 63, 70, 71, 144.
sources, 66.
stratification of granules, 68.
structure of granules, 70.
swelling, 70.
tapioca, 69.
Tous les Mois, 69.
uses, 68.
viscosity of paste, 70.
wheat, 68, 69.
Steam steriliser, 366.
temperatures, 406.
Steely corns, 191.
Sterilisation, 350.
apparatus, 366.
nutrient media, 365.
wort, 295.
Steriliser, steam, 366.
Stern 1 , asparagine, 86.
Stirring rods, 6.
Stock ale, dextrin percentage, 218.
Stoppers, boring, 6.
rubber, 7.
Stohmann and Langbein, crystallised
proteid, 84.
Stone square yeast, 347.
Stout, water for brewing, 180.
Strig, hop, 313.
Strontia, 146.
Sugar, 316.
acid process of inversion, 319.
analysis, 258.
arsenic, 272, 277.
beet, 318.
caramel, 325.
coffee, 141.
crystallisation, 317.
cupric oxide reducing power, 400.
decomposition, 391.
glucose, 265, 323.
inversion, 118, 318, 321.
invert, 258, 322.
composition, 388.
iron, 260.
mineral matter, 258.
invertase process of inversion, 321.
malt, 63.
milk, 63.
moisture, 259.
raw, 316.
reducing values, 400.
refined, 316.
rendement, 317.
yeast process of inversion, 321.
Sulphite of potash, 297.
of soda, 297.
Sulphites, 189, 296.
Sulphur, hops, 242.
malting, 270.
Sulphuric acid, analysis, 147.
for sugar inversion, 272, 320.
normal, 130.
table, 146.
Sykes hydrometer, 31.
proteid molecule, 99.
proteids in malt, 100.
Syntonin, 99.
Syrups, 388.
analysis, 268.
composition, 389.
priming, 268, 325, 389.
Tabloid, 297.
Taka ferment, 115.
Tangl and Haberlandt, dissolution
of starch cell wall, 113.
Tanniu, hop, 144, 238, 315.
Tapioca, 66.
starch, 69.
Tartaric acid, 146.
Temperature scales, 13.
conversion, 14.
Temporary hardness, 287-
Thames water, ammonia in, 168.
Thausing, viscosity of beer, 310.
Thermometer, 10.
barometric pressure, 12.
calibration of, 11.
construction of scale, 13.
determination of boiling and
freezing points, 12.
filling, 11.
graduation, 11.
Thermostat, 26.
Thimble of bibulous paper, 226.
Thompson and Escourt, arsenic, 270.
Thorpe, distilling apparatus, 29.
Tidy, oxygen process, 171, 282.
Tintometer, 36. See also under
Colour.
series of glasses, 36.
Titration, 128.
Toluol, 193.
Tongs, crucible, 10.
Torrubia militaris, 338.
Total solids, water analysis, 156.
Tourmalin, 40.
Tous le Mois starch, 69.
Toxins, 88.
Translocation diastase, 98, 102.
Tray, forcing, 367.
test, 376, 378.
Trypsine, 95, 96.
Tubes, boiling, 10.
ignition, 5.
Tiinnermann and Richter, caustic
alkali table, 404.
Tulkowsky, invertase, 114.
422
INDEX
Twaddell hydrometer, 31.
Tyndall, glycerine and bacteria, 370.
laws of light, 43.
lectures on light, 44.
spores, 366.
Typical analyses, 379, 384, 385.
Tyrer-Marsh apparatus. 243.
flask, 274.
Tyrosine, 85, 86.
Ulmic acid, 73.
Ulmin, 73.
Ure, hydrochloric acid table, 402.
nitric acid table, 403.
Urea in water, 285.
Urine in water, 285.
Urocystis occulta, 341.
Ustilagine*, 339.
Ustilago carbo, 341.
Vacuole of yeast, 346.
Van Leent, solution weights, 58.
Vegetative energy and capacity of
barley, 236.
Ventzke-Scheibler, polarimeter, 49.
Vinegar, mother of, 333.
Viscosity of beer, 310.
of starch paste, 70.
Viscous ferment, 332.
Vitellin, 82, 90.
Volumetric analysis, calculation of
results, 128.
chemicals, 145.
multipliers, 146, 394.
non-permanent solutions, 130.
permanent solutions, 130.
solutions for, 128.
standardisation, 141.
See also Standard and other Solu-
tions.
Water, bacteria, 294.
biological examination, 294, 369.
boiling point, 406.
chalk, 286, 289.
clay, 286.
classification, 286.
contamination, 282.
Dublin, 288.
Edinburgh, 288.
germs in, 294.
hard, 286.
hardness, 287.
limestone, 286.
London, 289.
loose sand and gra\ 7 el, 286.
manipulation, 290.
marsh and moor, 287.
medium, 288.
micro-organisms, 294.
mild ale, 179, 290.
millstone grit, 286.
Water, natural, 279.
organisms in, 294.
pale ale, 289, 290.
porter, 180.
saline constituents, 285, 286.
manipulation, 290.
sea salt in, 284.
selenic, 287.
soft, 286.
stout, 180.
subsoil, 287.
surface, 287.
urine in. 285.
well, 280.
Water analysis, 153, 279.
acids and bases, 175.
alkalinity, 162.
ammonia, 168, 281.
biological examination, 294, 369.
chlorine, 160, 284.
copper, 174.
colour, 155.
determinations, 153.
filtration, 155.
iron, 161.
lead, 174.
lime, 157.
magnesia, 159.
Nesslerising, 169.
nitrates, 165, 283.
nitric acid, 165.
nitrites, 165, 284.
nitrous acid, 167.
organic matter, 157, 168, 282.
oxygen absorbed, 171, 282.
saline residue, 156.
salts, 175.
sampling, 154.
silica, 173.
smell, 155.
soda and potash, 163.
sodic chloride, 160.
sulphuric acid, 159.
suspended matter, 156.
total solids, 156.
Weighing, 16.
rules, 17.
Weight, solution, 57.
Weights and weighing, 16.
Weiss, proteolytic enzyme, 98.
Well water, 280.
Wheat, composition, 383.
starch, 69.
Wijsman, enzymes, 105.
Wild yeasts, 358, 363.
Williams, nitric acid in water, 166.
Winchester quarts, 154.
Wood, composition, 383.
Wort analysis, 213.
acidity, 215.
biological examination, 374.
barley, 224.
INDEX
423
Wort analysis, clearing, 219.
colour, 204.
cupric oxide reducing power, 201,
213.
combined dextrin, 223.
maltose, 222.
copper, 219.
maize, 224.
malto-dextrins, 221.
mash-tun, 218.
mineral matter, 216.
oat, 224.
opticity, 215.
proteids, 215.
raw grain, 218.
rice, 224.
sterilisation, 295.
total solids, 213.
Xanthine, 88.
Xylose, 62, 63, 81.
Yearling hops, 314.
Yeast, 97.
arspnic, 277.
biological examination, 375.
composition, 348, 391.
cultivations, 355.
distinction from bacteria, 331.
Yeast, drying, 121.
enzymes, 96.
extract, 120.
fermentation by, 116.
of cane-sugar, 77.
of levulose, 75.
film formation, 360.
inversion of sugar by, 321.
invertase, 115.
koji, 102.
mineral matter, 391.
mould, 375.
nucleus, 347.
powder, 120.
pure, 364.
reproduction, 348.
spores, 358.
staining, 349.
stone square, 347.
sugar inversion, 321.
vacuole, 346.
varieties, 358.
wild, 358, 363.
Zeiss, hsematimeter, 355.
Zinc, arsenic in, 277.
copper coating, 166.
Zygospore, 339, 344.
Zymase, 77, 119, 122.
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