I

A PRACTICAL TREATISE

ON THE

MANUFACTURE OF VINEGAR AND ACETATES,
CIDER, AND FRUIT-WINES.

A PRACTICAL TREATISE

ON

PRESERVATION OF FRUITS AND VEGETABLES BY
CANNING AND EVAPORATION;

PREPARATION OF FRUIT-BUTTERS, JELLIES, MARMALADES,
CATCHUPS, PICKLES, MUSTARDS, ETC.

EDITED FROM VARIOUS SOURCES,

BY

WILLIAM T. BRANOT,

ONE OF THE EDITORS OF "THE TECHNO-CHEMICAL EECEIPT BOOK."

ILLUSTRATED BY SEVENTY-NINE ENGRAVINGS.

PHILADELPHIA :
HENRY CAREY BAIRD & CO.,

INDUSTRIAL PUBLISHERS, BOOKSELLERS, AND IMPORTERS,
810 WALNUT STREET.

LONDON :

SAMPSON LOW, MARSTON, SEARLE & RIVINGTON, LIMITED,
ST. DUNSTAN'S HOUSE, FETTER LANE, FLEET STREET, E. c.

1890.

71

COPYRIGHT BY
HENRY CAREY BAIRD & CO.

1889.

PRINTED AT THB COLLINS PRINTING HOUSE,

705 Jayne Street,
PHILADELPHIA, U. S. A.

0*

VII7ERSITT

PREFACE.

IT is quite unnecessary here to enlarge upon the prominence
and the commercial value of the products of the various branches
of industry treated of in this volume, since they are indispensable
requisites as well in domestic economy as in the arts. But not-
withstanding the great importance of .these subjects, little reliable
information in regard to them is found in our technical literature,
and that little is so widely scattered as to make it almost inac-
cessible to most manufacturers.

Of all the branches of industry based upon chemical processes,
the manufacture of vinegar has made the least progress, and con-
sequently disturbances and large losses of material are here of
much more frequent occurrence than in other fermenting indus-
tries which are carried on in accordance with established rules,
whose correctness has been ascertained by many experiments.

With few exceptions there are no works in the English lan-
guage in which an attempt has been made to establish the manu-
facture of vinegar upon a rational basis, and in accordance with
the laws of nature as regards the chemical as well as the physi-
cal processes. To attain this object as nearly as possible has
been the aim in the preparation of the portion of this volume
relating to vinegar. Since the physical processes, especially the
exact maintenance of determined temperatures and the production

yi PREFACE.

of a change of air corresponding to the chemical processes, play
an important role in the manufacture of vinegar, the section re-
lating to this subject has been very fully treated.

To the manufacture of wine-vinegar a space corresponding to
the importance of the subject has been devoted. Wine-vinegar
is undoubtedly the most valuable product of the vinegar industry,
and its fabrication might be made specially advantageous in this
country, since in California and other States a vast amount of
material could thus be profitably utilized, which otherwise would
go to waste. On account of its great interest considerable space
has been devoted to the manufacture of acetic acid from wood,
and of acetates, especially those which are used for technical
purposes.

As regards the manufacture of cider and fruit-wines, the
preservation of fruit, etc., much time and care have been devoted
to the gathering of information from all available and widely-
scattered sources in order to do justice to the great and constantly
growing fruit industry of this country. Special attention has
been paid to evaporation, since this process is likely to supersede
all other modes of drying fruit.

The volume is divided into three parts, upon each of which a
few observations are offered.

Part I. treats of the Manufacture of Vinegar. It is chiefly
based upon the German works, Die Schnell-Essig Fabrication
und die Fabrication von Weine&dg, by Dr. Josef Bersch, and
Lehrbuch der Essigfabrikation, by Dr. Paul Bronner. Both are
works of acknowledged authority, in which the authors have
brought together the results of their experience of many years.

PREFACE. VI 1

Part II. contains the Manufacture of Cider and Fruit-wines,
and Part III. Canning and Evaporating of Fruit, etc. For in-
formation on these subjects we are indebted to the French work,
Culture du Pommier d Cidre, Fabrication du Cidre, etc., by Jules
Nanot, and to the German works, Die Hebung der Obstverwerth-
ung und des Obstbaues, by Heinrich Semler, and Die Obstwein-
kunde, by Dr. N. Graeger. Wherever required, the information
derived from the above works has been supplemented by Amer-
ican processes.

The editor also acknowledges his indebtedness to numerous
American and English authors for valuable information, due
credit for which has been given whenever possible.

A copious table of contents as well as a very full index will
render reference to any subject in the book prompt and easy,
and the whole treatise is submitted to the public with a feeling
of confidence as to its value and usefulness.

WILLIAM T. BEANNT.

PHILADELPHIA, Sept. 26, 1889.

CONTENTS.

PART I.

THE MANUFACTURE OF VINEGAR.
CHAPTER I.

INTRODUCTION.

PAGE

Ordinary vinegar, what it is ; The discovery of vinegar ; Use of vinegar
as a medicine by Hippocrates ; Early knowledge of the property of
vinegar of dissolving calcareous earths ; The dissolving of large pearls
in vinegar by Cleopatra . . . . . . . . .17

The use of vinegar by Hannibal for dissolving rocks ; No early definite
knowledge of the cause of the production of vinegar; The process
of increasing the strength of wine-vinegar made known by Gerber in
the eighth century; Other historical data regarding vinegar; The
first preparation of acetic acid in a pure state and the discovery of
the property of very strong acetic acid to crystallize at a low temper-
ature ; Historical data regarding the formation of an acid body in the
dry distillation of wood ; Determination of the exact chemical consti-
tution of acetic acid by Berzelius and that of alcohol by Saussure ;
Historical data relating to the generation of acetic acid . . .18
The introduction of the quick process of manufacturing vinegar, in 1823,
by Schiitzenbach ; A method of manufacturing vinegar from wine
made known by Boerhaave ; ScMitzenbach's original plan of working
still in use in some localities ; Necessity of progress in the manufac-
ture of vinegar by the quick process; The constantly increasing diffi-
culties in the manufacture of vinegar from alcohol . . . .19

Great purity of the acetic acid at present produced from wood ; Use of
"vinegar essence" for pickling, etc. ; Difference between the acetic
acid produced from wood and vinegar prepared from various sub-
stances ,....... 20

Principal defects in manufacturing vinegar by the quick process in general
use ... 21

X CONTENTS.

CHAPTER II.

THEORY OF THE FORMATION OF VINEGAR.

PAGE

Explanation of the chemical processes by which acetic acid in large
quantities is formed ......... 21

Liebig's theory of the formation of vinegar ; The formation of vinegar
due to a chemico-physiological process ...... 22

Pasteur's theory of the formation of vinegar; Difference between
Pasteur's and Nageli's views; Nomenclature of organisms producing
fermentation ; The vinegar or acetous ferment ; Origin of the acetic
acid formed in alcoholic fermentation ...... 23

Occurrence of acetic acid in nature ; Formation of acetic acid by chemi-
cal processes ; Formation of acetic acid by the action of very finely
divided platinum upon alcohol, illustrated ..... 24

Development of " mother of vinegar" ...... 25

Pasteur's examination of the relations of the mother of vinegar to the
formation of vinegar; The botanical nature of the organisms causing
the formation of vinegar ; Disease-causing bacteria ... 26

What constitutes the entire art of the manufacture of vinegar . . 27

CHAPTER III.

THE VINEGAR FERMENT AND ITS CONDITIONS OF LIFE.

The vinegar ferment, its origin and distribution ; Fluid especially
adapted for its nourishment 27

Experiment showing the conversion of wine into vinegar by the vinegar
ferment, with illustration ........ 28

Duration of life of the vinegar ferment ; Difference between the living
and dead ferment as seen under the microscope ; Requirements of
the vinegar ferment for its augmentation . . . . .29

Results of the withdrawal of oxygen from the vinegar ferment ; Ex-
periment showing the great rapidity of the augmentation of the
vinegar bacteria ; Nourishing conditions of the vinegar ferment . 30

Factors required for the settlement of the vinegar bacteria upon a fluid
and for their vigorous augmentation ; Composition of the nourishing
fluid ; A large content of alcohol in the nourishing fluid detrimental
to the vegetation of the vinegar ferment ; Experiment showing that
the vinegar ferment cannot live in dilute alcohol alone . . .31

The preparation of a fluid containing all the substances essential to the
nourishment of the ferment ; Sensitiveness of the vinegar ferment to
sudden changes in the composition of the fluids upon which it lives ;
The process of nourishment of the vinegar ferment . . .32

Supply of air required by the vinegar ferment ; Limits of temperature
at which the augmentation of the ferment and its vinegar-forming

CONTENTS. XI

PAGE

activity are greatest ; Action of the ferment when exposed to high

and low temperatures . . . . . . . . .33

Difficulty of rearing the vinegar ferment upon a cold fluid ; Reason why
acetous degeneration is not known in cold wine cellars ; Reasons for
the ready occurrence of disturbances in the formation of vinegar at a
high temperature ; Mother of vinegar ; Origin of the term . . 34

Occurrence, appearance, and growth of mother of vinegar ; Different
opinions as to the nature of mother of vinegar . . . .35

Composition of the mother of vinegar according to Mulder and R. D.
Thomson ; Substances which participate in the formation of mother
of vinegar, illustrated by an experiment ; How the formation of
mother of vinegar can be successfully attained . . . ,36

General occurrence of mother of vinegar in young wine ; Erroneous
opinion as to the part mother of vinegar takes in the formation of
vinegar; Summary of the theoretical conditions of the formation of
vinegar of importance to the manufacturer . . . . .37

CHAPTER IV.

PRODUCTS OF ACETOUS FERMENTATION.

The regular augmentation of the ferment the main point of the entire
fabrication ; Occurrence of loss of alcohol in the fabrication . . 38

Bodies, besides alcohol and carbonic acid, formed in the vinous fermen-
tation ; Characteristic properties imparted to alcohol by fusel oils ;
Aromatic substances which reach the vinegar through the conversion
of fusel oils; Acetic aldehyde or acetaldehyde . . . .39

Preparation and constitution of pure aldehyde ; Acetal ; Preparation
of acetal 40

Composition and nature of pure acetal . . . . . .41

Acetic acid ; Glacial acetic acid ; Properties of acetic acid ; Peculiar
behavior of mixtures of acetic acid and water in regard to their
specific gravity 42

Difference in the determinations of specific gravities of acetic acid with
a varying content of water ; Uses of highly concentrated acetic acid ;
Composition of acetic acid ........ 43

Theoretical yields of acetic acid ; Theoretical and practical yields, what
they are ; Mariner of calculating the theoretical yield of acetic acid
from alcohol ........... 44

Quantity of oxygen consumed in the formation of vinegar ... 45

Quantity of alcohol which can be daily converted into vinegar by a vine-
gar generator ; Calculation of the quantity of heat liberated by the
conversion of alcohol into acetic acid ; What the practical manufac-
turer can learn from theoretical explanations 46

Xll CONTENTS.

PAGE

Proof that the generators now in use are deficient ; The optimum tem-
perature, what is meant by it ; Loss of alcohol and acetic acid by
evaporation and its reduction to a minimum . . . . .47

Conditions on which the most advantageous manner of working depends;
Yields of acetic acid obtained in practice ; Unavoidable losses in a
vinegar factory ; Defectiveness of the processes in general use and
the necessity for reformation . . . . . . . .48

Comparison of a vinegar generator to a furnace . . . . .49

CHAPTER Y.

METHODS OF FABRICATION OF VINEGAR.

Reasons for not commencing the description of the various methods of
fabrication of vinegar with the oldest and most simple method known,
viz., the fabrication of vinegar from wine ; Why we can speak of
grain and malt vinegars ......... 50

Alcohol the ultimate material for the fabrication of vinegar ; The slow
and quick processes of fabrication ; Modifications in the old process
according to the materials used . . . . . . .51

Difference in the properties of vinegar derived from various sources . 52

CHAPTER VI.

QUICK PROCESS OF FABRICATION OF VINEGAR.

Invention of Schutzenbach's and analagous processes ; On what the
principle involved depends 52

Appropriateness of the term " quick process;" Comparison of the
generator or "graduator" to a furnace ; Difficulty of conveying the
requisite amount of air to the generator ...... 53

Arrangement of the generators ; The best form of the generator, with
illustration 54

Variation in the dimensions of the generators ; Disadvantages of small
and of large generators ........ 55

Erroneous opinions in regard to the manufacture of strong vinegar; Di-
mensions of the most suitable generators ; Cover of the generator,
with illustration 56

Disadvantage of a number of obliquely bored apertures below the false
bottom, with illustration .... 57

Different forms of generator ; Self-acting discharge arrangement, with
illustration . . . . . . . . . . .58

Disadvantage of the self-acting discharge arrangement and substitute
for it ; Arrangement of the disk or false bottom of the generator,
with illustration . 59

CONTENTS. xiii

PAGE

Arrangement for regulating the influx of air from below, with illustra-
tion 60

Modification of the disk, with illustration ; The tilting trough, with
illustrations . . . . . . . . . . .61

Arrangement and manner of working of the tilting trough ; The sparger
described and illustrated . . . . . . . .62

The principal requisite of the correct working of the sparger, with illus-
tration ; Difficulties overcome by the use of the sparger ... 64

A thermometer an indispensable adjunct to a generator; Manner of
locating the thermometer ; Filling of the generators ; Materials used
for filling the generators ; Advantages of beechwood shavings . 65

Preparation of beech shavings ; Volume represented by a shaving in a
rolled state ; Space required for each shaving ; Size of the space to
be filled with shavings in a generator ; Number of shavings required
to fill this space ; Surface of shavings active in the formation of vine-
gar ; Steaming of the shavings ' 66

Drying of the shavings ; Swelling of the shavings . . . .67

Manner of placing the shavings in the generators ; Advantage of hav-
ing all the generators of the same size 68

CHAPTER VII.

ARRANGEMENT OF A VINEGAR FACTORY.

Unsuitableness of the arrangement of the manufacturing rooms formerly
customary ; The principal requisites for a suitable arrangement of the
factory 68

Arrangement of the walls, windows, doors, and floor of the factory ;
Height of the workroom : Heating of the workroom ; The best
arrangement where stoves are used ; Heating apparatus for large
factories described and illustrated . . . . . . .69

Necessity for thermometers in the workroom ; The maximum electrical
thermometer described and illustrated ...... 71

The minimum electrical thermometer ; Location of the reservoirs in
a factory arranged according to the automatic system . . .72

CHAPTER VIII.

ARTIFICIAL VENTILATION OF THE VINEGAR GENERATORS.

The English process of sucking a current of air from above to below
through every generator, with illustrations ; Incorrectness of this *
process . 73

The principal reason advanced for the use of a current of air from above
to below ... 74

xi v CONTENTS.

PAGE

Schulze's ventilating apparatus, with illustrations; Description of

Sehulze's generator .75

Objections to Schul/e's apparatus .... 76

Generators with constant ventilation and condensation ; The object of

special ventilating contrivances ; Ventilating apparatus according to

Bersch, described and illustrated ..... .77

Condensing apparatus, described and illustrated ... .78

Proposed method of regaining the vapors ; Objection to this method . 80

CHAPTER IX.

AUTOMATIC VINEGAR APPARATUS.

The principal work which has to be performed in a vinegar factory . 80
Disadvantages of pouring at stated intervals the alcoholic fluid into the
generators ........... 81

Advantages to be derived from the use of simple automatic contrivances ;
Division of continuously working apparatus into two principal sys-
tems ; Continuously working apparatus the terrace system . . 82
A factory arranged according to the terrace system described and illus-
trated 83

Objections to the terrace system 84

Advantages of the group system ; Mode of distributing the alcoholic

liquid into each generator in the terrace system . ... .85
Periodically working apparatus the three-group system ; Modification

of the tilting trough, described and illustrated 87

The siphon barrel, described and illustrated 88

The bell-siphon, described and illustrated 89

Example for calculating the space required beneath the lath-bottom of
the generator for the reception of the fluid ; Arrangement of a vinegar
factory working according to the automatic principle ... 90
Manner of arranging the generators in groups ; Height of the actual
work-room ; Location of the reservoir and of the collecting vessels ;
Description of a periodically working establishment with 24 generators 91
Manner of working in such an establishment ..... 93
Material for metallic vessels used in the factory ; Location of the pump ;
Advantage of heating the alcoholic liquid before its introduction into
the generators ; Apparatus for heating the alcoholic liquid described
and illustrated ....... 94

CHAPTER X.

OPERATIONS IN A VINEGAR FACTORY.

Acidulation of the generators ; Object of acidulation ; Manner of {undu-
lation ; Quantities of vinegar required for complete acidulation 96

CONTENTS. xy

Example illustrating the gradual commencement of the regular fabrica-
tion ; Accelerated acidulation ; Objection to the ordinary method of
accidulation ......

Percentage of water in the shavings which has to be replaced in the ordi-
nary method of acidulation by vinegar ; How the removal of water
from the shavings and its substitution by vinegar are effected; Time
required for acidulation by the old method ; Loss of vinegar in the
old method of acidulation ; Advantage and mode of using artificially
dried shavings ; Time required for acidulation with artificially dried
shavings ........ 9#

Induction of the operation with artificially raised vinegar ferment;
" Pure cultivation" of the vinegar ferment 99

Preparation and treatment of fluids for the pure cultivation of vinegar
ferment ........ 10o

Preparation of nourishing fluid from beer ; Manner of cultivating vine-
gar ferment . . . . . . . . . . .101

Abortive cultivation of vinegar ferment with illustrations ; Transfer of
the pure cultivation of vinegar ferment to the generators . . 102

Prevention of disturbances which are caused by suddenly changing the
nourishing fluid of the vinegar ferment 103

CHAPTER XI.

PREPARATION OF THE ALCOHOLIC LIQUID.

Definition of the term "alcoholic liquid;" Reason why a content of
vinegar in the alcoholic liquid exerts a favorable effect upon the forma-
tion of vinegar ; Proof that the alcoholic liquid does not require any
considerable quantity of acetic acid for its conversion into vinegar . 104

Reasons why it is preferable to gradually increase the content of alcohol
in the alcoholic liquid instead of at once adding the total amount . 105

Experiment illlustrating the destruction of acetic acid by (he vinegar
ferment in the absence of alcohol ; Limit of percentage of acetic acid
vinegar should have ; Conditions on which the advantageous fabrica-
tion of high-graded or weak vinegar depends .

Quantities of beer and of finished vinegar to be added to the alcoholic
liquid ; Table showing the theoretical yield of acetic acid from alcohol 107

Reasons why practically less vinegar with a smaller percentage of acetic
anhydride is obtained ; Table showing the content of alcohol required
in an alcoholic liquid for the production of vinegar with a certain con-
tent of acetic acid . . . .*.

Calculation for finding the number of gallons of water which have tc
added to alcohol of known strength in order to obtain an alcoholi
liquid with the desired percentage of alcohol ; Examples of the c
position of alcoholic liquid ..

XV111 CONTENTS.

CHAPTER XIY.

METHOD OF THE FABRICATION OF VINEGAR IN APPARATUS OF

SPECIAL CONSTRUCTION.

PAGE

Inutility of most inventions for overcoming the frequent disturbances in
the working of a factory not provided with suitable heating and venti-
lating arrangements ......... 139

Singer's vinegar generator, illustrated and described .... 140

Alirhaelis's rotary vinegar generator ....... 142

Fabrication of vinegar with the assistance of platinum black, and the
apparatus used .......... 143

CHAPTER XV.

FURTHER TREATMENT OF FRESHLY-PREPARED VINEGAR.

The odor of freshly- prepared vinegar and on what it depends ; Filling
of the barrels ; The reciprocal action which takes place between the *
air and the vinegar . . . . . . . . .144

Means for improving the odor of vinegar; Manner of drawing off the

vinegar from the sediment in the barrel, with illustration . .145

The storing of vinegar . . . . . . . . .146

Processes which take place during storing . . . . .147

Advisability of filtering the vinegar; Heating the vinegar; Apparatus
for heating the vinegar, illustrated and described .... 148

Filtration of the vinegar ; Filter for vinegar, illustrated and described . 150
Bag-filter for filtering vinegar under pressure, illustrated and described 151

Sulphuring of vinegar 152

Fining of vinegar ; Coloring vinegar .... 153

Preparation of caramel or burnt sugar .... 154

CHAPTER XYI.

PREPARATION OF VINEGAR FROM VARIOUS MATERIALS.
The formation of diastase ; How vinegar can be prepared from starch . 154
How the various kinds of vinegar might be designated according to the

elementary material used ; Reasons why beer-wort does not seem a

suitable material for vinegar ....
Use of fermented whisky-mashes for the manufacture of vinegar;

Manufacture of vinegar from malt and grain ; Combination of "the

manufacture of compressed yeast with that of vinegar . 156

The most suitable variety of malt for the preparation of vinegar* The

constitution of malt ....

.157

CONTENTS. XIX

PAGE

The theoretical part in mashing; Effective diastase; After-effect of
the diastase; Calculation of the yield of acetic-acid which can be
obtained from a given quantity of malt . . . . . .158

Use of a mixture of malt and-unmalted grain ; Doughing in the ground
malt; Mashing . . . . . . . . .159

The percentage of alcohol contained in mashes after fermentation;

Setting the rnash with yeast; Preparation of compressed yeast . 160

Treatment of the completely fermented "ripe mash" for the fabrica-
tion of vinegar ; Preparation of alcoholic liquid from filtered mash ;
Conversion of the fermented malt wort into vinegar . . .161

Filtration of malt vinegar in refining or rape vessels ; " Rape," what it
is; the manufacture of malt vinegar by "fielding"; Utilization of
sour ale and beer for vinegar . . . . . . .162

Preparation of vinegar from sugar beets ; Vinegar from sugar, fruits,
and berries . . . . . . . . . .163

Receipts for making vinegar by Cadet-Gassicourt and Doebereiner ;
Preparation of vinegar on a small scale for domestic use . .164

Table showing the average content of sugar and free acid in the most
common varieties of fruits ; Treatment of currant juice for the prepa-
ration of vinegar . . . . . . . . .165

Preparation of vinegar from bilberries ; Vinegar from berries ; Cider
vinegar ........... 166

Contrivance for making cider vinegar described by S. E. Todd . 167

Vinegar from apple-pomace 168

CHAPTER XVII.

PREPARATION OF VINEGAR SPECIALTIES.

Groups of specialties ; Perfumed vinegars 168

Aromatized vinegar; Manner of dissolving volatile oils in vinegar . 169
Preparation of aromatized vinegars . . . . . . .170

Toilet vinegars; Mohr's volatile spirits of wine ; Aromatic vinegar;
Henry's vinegar ; Vinaigre de quatre voleurs ; Hygienic or preven-
tive vinegar ; Cosmetic vinegar .171

Table vinegars ; Anise vinegar ; Anchovy vinegar ; Tarragon vinegar ;

Compound Tarragon vinegar ; Effervescing vinegar . . .172

Herb vinegar ; Pineapple vinegar ; Celery vinegar ; Clove vinegar ;

Mustard vinegar ; Lovage vinegar ; Preparation of acetic ether . 1 73
Preparation of a fluid for imparting bouquet to table vinegar ; Compo-
sition of pure acetic ether 1 74

XX 11 CONTENTS.

PAGE

Decomposition of wood at a higher temperature ; Cause of the decom-
position of wood ; Reason why a large amount of acetic acid is pro-
duced during the destructive distillation of wood . . . .219

Substances given off during the destructive distillation of wood ; Actual
facts observed in the distillation of wood ; Distillation of wood ; Re-
torts used in the distillation of wood; Form of the retorts . . 220

Dimensions of the retorts ; Position of the retorts ; Retorts used in
France ......... 221

Retorts used in England and Germany ; Vertical retorts ; Kestner's
apparatus, illustrated and described .... 222

Movable retorts, illustrated and described ; Modification of movable re-
torts, illustrated and described 223

Horizontal retorts, illustrated and described .... 225

Apparatus for abstracting the charcoal from the carbonizing cylinders ;
Condensers; Kestner's apparatus, illustrated and described . 227

Collection of the gases in a gasometer; Vincent's plan for cooling the
current of gas and rendering the vapors of acetic acid harmless, Illus-
trated and described 228

Dimensions for a condenser for four retorts, by Gillot ; Most suitable
varieties of wood for the production of wood- vinegar ; Removal of
the bark from the wood ...

Charcoal; Composition of charcoal ; Processes tak ing' place' by h'eatina
the wood in the retorts; Charbon roux or terrified charcoal- Red
wood (roasted wood, boix roux) and its composition ; Charcoals avail-
able for technical purposes

Quantity of charcoal obtained at various temperatures j Influence of the
degree of carbonization and of the variety of wood upon the yield of
charcoal; Variation in the elementary composition of charcoal as
found by Violette .

im 'S'" : ; Properties of 'tar and of woocU

Constituents of wood-vinegar

Woo.1 spirit (methyl aleohol), CH.O, and it's propertied and uses ;' Ace' ***

tone or d.methyl kctone (C 3 H 6 O) and its properties
Determ.nat.on of the strength of W ood-vi,,egar ; Mohr's me'thod '
L. Rieffer's method ... -235

Working up the wood-vinegar ; Methods by" which this' is effected' Dis' ^

tillation of wood-vinegar, described and illustrated
The recreation of wood-vinegar, described and illustrated '

Scation of wood-vinegar according to Terreil and Chateau - lathe's

method for the purification of wood- vinegar
Acetic acid for technical purposes

Preparation of crude calcium acetate ' ' ' ' 24

. 241
and pure sodium

242

CONTENTS. XX111

PAGE

Apparatus for roasting the pale brown sodium acetate, illustrated and
described ; Crystallizing vessels, illustrated and described . . 244

Mollerat's method of preparing sodium acetate 245

Acids, besides acetic acid, which occur in wood- vinegar according to
Barr6 246

Vincent's method of decomposing the mother-lye ; Manner of obtaining
wood-spirit (methyl alcohol) ; Composition of crude wood-spirit;
Processes which take place in digesting crude wood-spirit with slaked
lime ............ 247

Apparatus for distilling the digested mixture, illustrated and described 248

Further purification of wood-spirit; Purification of wood-spirit on a
small scale ; Examination of commercial wood-spirit . . . 249

Yield of charcoal, wood-vinegar, and wood-spirit as well as of tar;
Stoltze's experiments on the products obtained from the distillation
of several varieties of wood . . . . . . . .250

Percentage of acetic anhydride which, according to Gillot, can be ob-
tained from hard wood . . . . . . . . .251

Results obtained by Assmus in manufacturing on a large scale ; Rothe's
experience in obtaining acetic acid and other products from birch ;
Yield of salable methyl alcohol according to Vincent ; Description
of Halliday's apparatus 252

Wood-vinegar from saw-dust ........ 253

CHAPTER XXII.

PREPARATION OF PURE CONCENTRATED ACETIC ACID.

Percentage of acetic acid in the strongest vinegar which can be pre-
pared by the process of fermentation 253

Advisability of increasing the strength of vinegar from alcohol by the
addition of concentrated acetic acid from wood ; Detection of empy-
reumatic substances in acetic acid from wood ; Acetic acid from wood
for the preservation of fruit, cucumbers, etc. ... . 254

Manner of obtaining acetic acid from strong vinegar; Stein's method
of increasing the boiling point of vinegar 255

Preparation of acetic acid from commercial acetates and from those ob-
tained from wood- vinegar ; Former method of obtaining glacial acetic
acid ; Principal acetates now used for the preparation of acetic acid ;
Preparation of acetic acid from normal lead acetate (sugar of lead) . 256

Bucholz's direction for the preparation of acetic acid from lead acetate ;
Preparation of acetic acid without distillation 257

Decomposition of lead acetate by nitric acid ; Calcium acetate and so-
dium acetate the basis for the preparation of acetic acid on a large
scale ; Volckel's method of preparing acetic acid from calcium ace-
tate . . . 258

XXIV CONTENTS.

PAGE

Test for ascertaining the quantity of lime required for rectifying acetic
acid 259

Rectification of acetic acid, illustrated and described ; Use of the ace-
tate prepared from crude wood- vinegar for the preparation of acetic
acid . . - 26

Reichenbach's method of destroying empyreumatic bodies in crude cal-
cium acetate ; Schnedermann's method .... 261

Preparation of acetic acid from sodium acetate .

Yield of acetic acid from crystallized sodium acetate ; Mollerat's method
of preparing acetic acid from sodium acetate, illustrated and described 263

Glacial acetic acid ; Melsen's method of preparing glacial acetic acid . 265

Calcium chloride as a by-product in the preparation of glacial acetic
acid ; Oil of lemon as a test for pure acetic acid ; Properties of gla-
cial acetic acid . . . . . . .266

CHAPTER XXIII.

ACETATES AND THEIR MANUFACTURE.

Constitution of acetic acid ........ 266

Solubility of acetates ; Preparation of acetates ; Potassium neutral ace-
tate 267

Properties and uses of potassium acetate ; Potassium acid acetate or

potassium diacetate ......... 268

Sodium .toetate ; Properties and uses of sodium acetate ; Sacc's method

of preserving meats and vegetables with sodium acetate . . . 269

Explosive mixture prepared with the use of sodium acetate; Ammo-
nium acetate, neutral acetate of ammonia; Calcium acetate . . 270

Barium acetate ; Mode of obtaining acetone from barium acetate . 271

Strontium acetate ; Magnesium acetate ; Aluminium acetate ; Import-
ance of aluminium acetate in calico printing; Mode of preparing
aluminium acetate for the use of the calico printer .... 272

Preparation of a mordant by decomposing alum by lead acetate ; lle-
ceipts for preparing red liquor ; Crace-Calvert's recommendation of
the use of sulphacetate of alumina for the preparation of mordant,
with formulae 273

Messrs Storck & Co.'s, of Asniferes, France, process for the manufac-
ture of aluminium acetate from the phosphate; Manganese acetate 1
Preparation of manganous sulphate ..... 274

Iron acetates ; Ferrous acetate ....... 275

Properties and use of ferrous acetate ; Neutral ferric acetate or sesqui-
acetate of iron . .... 276

Mode of preparing pure neutral ferric acetate . . . . 277

Uses of the acetates of iron ; Chromium acetates . . . 278

CONTENTS. XXV

PAGE

Chromous acetate ; Chromic acetate ; Nickel acetate ; Cobalt acetate ;

Zinc acetate 279

Acetates of copper ; Cuprous acetate ; Neutral cupric acetate, or crys-
tallized verdigris .......... 280

Method of obtaining neutral cupric acetate by double decomposition . 281
Crystallization of neutral cupric acetate; Properties and uses of neutral
cupric acetate .......... 282

Basic cupric acetates ; Sesquibasic cupric acetate ; Dibasic cupric acetate ;

Tribasic cupric acetate ; Varieties of verdigris found in commerce . 283
Manufacture of verdigris in France ....... 284

Manufacture of verdigris in England, Germany, and Sweden ; Compo-
sition of French and English verdigris according to Philipps ; Methods

of testing verdigris as to adulterations 285

Uses of cupric acetates ; Scheele's green ; Schweinfurth green . . 286
Lead acetates; Neutral acetate of lead (sugar of lead) . . .287
Stein's method of preparing neutral acetate of lead, illustrated and
described ........... 288

Berard's process of preparing sugar of lead . . . . .291

Other methods of preparing sugar of lead ...... 292

Properties of neutral acetate of lead . . . . . . .293

Uses of sugar of lead . .294

Basic lead acetates ; Manufacture of white lead according to the French

method ; Preparation of lead vinegar or extract of lead . . .295
Lead sesquibasic acetate, triplumbic tetracetate ; Tribasic acetate of
lead ; Preparation of tribasic acetate of lead according to Pay en ;
Manufacture of white lead by the Clichy process and by the Dutch
process ; Sexbasic acetate of lead ....... 296

Uranium acetate; Tin acetate; Bismuth acetate ; Mercurous acetate t 297
Mercuric acetate ; Silver acetate ....... 298

PART II.

MANUFACTURE OF CIDERS, FRUIT- WINES, ETC.
CHAPTER XXIV.

INTRODUCTION.

Definition of the term wine ; Ingredients which are added to artificial
wines ; Ripening of fruits ; Constituents of an unripe fruit . . 299

Occurrence and behavior of pectose ; Formation and properties of
pectine 300

Properties of metapectine ; Action and constitution of pectase ; Pec-
tous fermentation ; Formation of pectosic acid .... 301

CONTENTS.

PAGE

Formation and properties of pectic acid ; Formation and properties of
metupectic aeid ..... 302

Definition of the term isomeric ; Development and ripening of a fruit
viewed as chemical process 303

Results of chemical researches into the changes which fruits undergo
during their development and perfection ..... 304

Stages which a fruit passes through during development and ripening . 305

CHAPTER XXV.

FRUITS AND THEIR COMPOSITION.

Fruits used for the preparation of fruit-wines ; Compilation from
Fresenius giving the average percentage of sugar in different varie-
ties of fruit 306

Compilation according to average percentage of free acid ; Compilation
according to the proportion between acid, sugar, pectine, gum, etc. ;
Compilation according to the proportion between water, soluble, and
insoluble substances . . . . . . . . .307

Composition of the juice according to its content of sugar, pectine, etc. ;
Content of free acid in 100 parts of juice ..... 308

Grape-sugar or glucose ; Acids; Albuminous substances . . . 309
Pectous substances ; Gum and vegetable mucilage . . . .310

Tannin; Difference between pathological and physical tannin . .311
Inorganic constituents ; Fermentation ...... 312

Chief products of vinous fermentation ; Properties of absolute alcohol;

Succinic acid . . . . . . . . . .313

Glycerin; Carbonic acid . . . . . . . . .314

Quantity of carbonic acid developed during fermentation ; Alkaloid in
wine . 315

CHAPTER XXVI.

PRACTICE OF THE PREPARATION OF CIDER AND FRUIT-WINES.

Manner of gaining the juice or must from the fruit; Mr. W. O. Hic-

kock's portable cider mill . . . . ( t gig

Apparatus for crushing apples, illustrated and described ; Davis's star

apple grinder, illustrated and described 317

Presses; Manner of obtaining the juice from berries, etc. ; Manner of

obtaining the juice from apple-pomace, etc 318

44 Farmer's cider press," illustrated and described; "Extra power

cider press," illustrated and described ... 319

Revolving platform of the " extra power cider press," illustrated and

described ., 9n

. O & \J

Ferguson's improved racks 321

CONTENTS. XXV11

PAGE

Plain racks ; Willson's telegraph wine and cider mill, illustrated and
described ........... 322

Apple elevator, illustrated and described . . . . . .323

Testing the must as to its content of acid and sugar ; Manner of finding

the quantity of acid 324

Determination of the sugar in must ; Manner of calculating the quan-
tity of sugar which has to be added to the must to give the wine the

desired content of alcohol 326

Glucose 327

Properties of commercial glucose ; Determination of pure sugar in glu-
cose ; Anthon's table for finding the content of anhydrous grape-
sugar in saturated solutions of glucose ...... 328

CHAPTER XXVII.

CIDER FROM APPLES AND PEARS.

Cider from apples ; " Champagne cider" ; " Sparkling cider" . .329

Reputation of Normandy and Herefordshire and Devonshire ciders ;
Production of cider, in 1883, in France ; Analyses of Brittany ciders
by Rousseau ; Analyses of pure ciders from different parts of France
made in the Paris municipal laboratory 330

Average composition of French ciders ; Analyses of ciders by the
United States Agricultural Department 331

Choice of the varieties of apples for the manufacture of cider . . 332

Test for ascertaining the content of tannin in apples ; Mixtures of apples
used in France for the preparation of cider; Varieties of apples
chiefly used in New Jersey for the manufacture of cider ; List of
apples recommended by P. Barry for cultivation in the Eastern and
Middle States . 333

Mode of gathering and sweating apples for the preparation of cider . 334

Reduction of the apples to an impalpable pulp ; Diversity of opinion as
regards the crushing of the seeds ; Treatment of the pulp ; Pressing 335

Primitive custom of laying the cheese ; Substitution of hair-cloth and
cotton press-cloth for straw in laying the cheese ; Manufacture of
small cider in France ; Extraction of the juice by diffusion . . 336

M. Jules Nanot's improved method of extracting the juice by diffusion,
illustrated and described . . . . . . . .337

Expressing the juice by means of the centrifugal ; Testing the juice with
the must-aerometer and its correction if wanting in saccharine
strength ; Fermentation of the juice 339

Distinguishing characteristic between the fermentation of wine and
cider; Various methods of checking fermentation; Preparation of
very fine cider 340

XXviii CONTENTS.

PAGE

Salicylic acid as an agent for cheeking fermentation; The "salicylic

acid question" ; Manner of using salicylic acid . . . .341
Clarification of cider ; French method of clarifying cider ; Improving

the taste of cider 342

Preparation of cider in the same manner as other fruit-wines ; Red

apple-wine or red wine from cider; Sweet cider .... 343
Dr. Denis-Dumont's directions for bottling cider .... 344
Manufacture of cider in the Island of Jersey ; Devonshire cider ; Heating

of cider 345

Solution of the problem of keeping cider sweet ; Freezing of cider . 346
Champagne eider .......... 347

Artificial wines from cider; Burgundy; Malaga-wine; Sherry-wine . 348
Claret-wine ; Diseases of cider ; Acidity in cider ; Viscosity or greasy

appearance of cider ......... 349

Turning black of cider; Turbidity of cider ; Adulteration of cider . 350
Dr. Bremont on the adulteration of cider ; Adulteration of cider in

France ; Minimum limit for the composition of pure cider . . 351
Results of the investigation of American ciders by the United States

Agricultural Department ; Manufacture of brandy from cider . . 352
Preparation of the juice for distillation ; Brandy from plums, damsons,

etc. ; Distillation 353

Rectification of apple-brandy ; Pear-cider ...... 354

Preparation of " port-wine" from pear-must ; Quince wine . . 355

CHAPTER XXVIII.

FRUIT-WINES.

From small fruits ; Prevention of the turning of wine from small fruits ;

Advantage of a mixture of various juices for the preparation of wine ;

Means of improving the flavor and keeping qualities of fruit-wine . 356

Selection of the fruit ; Expression of the juice ; Fermentation . . 357

Clarification and drawing off of the wine into bottles ; Currant-wine . 358
Composition of currant-wine, two years old ; Preparation of a very

strong beverage from the juice of currants .... 359

VfMous methods of preparing strawberry-wine ..... 360

Gooseberry-wine ......... 361

Gooseberry-champagne . . . . . . . . 3^3

Sender's directions for the preparation of gooseberry-champagne . . 364

Raspberry-wine * . . 365

Blackberry-wine; Mulberry-wine; Elderberry-wine . . . SQQ

Juniperberry-wine ; Rhubarb- wine ; Tomato-wine . . . 357

Parsnip-wine ; Preparation of wine from stone-fruits ; Cherry-wine 368
Morello-wine ; Plum-wine; Apricot and peach-wines; Sloe or wild

plum-wine o fif)

CONTENTS. XXIX

PART III.

CANNING AND EVAPORATING OF FRUIT, MANUFACTURE
OF CATCHUPS, FRUIT BUTTERS, MARMALADES, JEL-
LIES, PICKLES, AND MUSTARDS.

CHAPTER XXIX.

PRESERVATION OF FRUIT.

PAGE

Rules applying to all methods of preserving fruit . . . .371

French method of preserving fruit, known as au Baine-Marie ; Preser-
vation of the flesh of the fruit without boiling ..... 372

Preparation of fruit for preserving ; Preservation of fine table pears ;
Boiling down of fruit in large stoneware pots . . . . .373

Preserving in air-tight cans ; National importance of this method for
the United States and England ; Groups of canned articles embraced
in the American trade lists . . . . . . . .374

Difficulties in canning plums and cherries ; Fruits suitable and unsuit-
able for canning; Selection of the fruits for canning . . .375

List of varieties of fruit preferred by the North American factories for
canning ; Preference of the California packers for the Bartlett pear ;
Various styles of cans and jars 376

Complaint against the use of tin cans ; The soldering of tin cans inside
prohibited in England ; Manner of coating and lining the inside of tin
cans to protect the contents from contact with the metal . . .377

Manufacture of tin cans in the United States canneries; Division of
labor in the canneries ; Preparation of the syrup . . . .378

Apparatus for the expulsion of air by heating the cans ; Cleansing and
testing the cans . . . . . . . . . .379

Mode of heating the cans in boiling water ; Canning of tomatoes . 380

Selection of a site for the canning establishment ; How contracts for a
supply of tomatoes are made ; Arrangement of a canning factory . 381

Scalding the tomatoes; Skinning the tomatoes ; Machines for filling the
cans 382

" Cappers" and their work ; Labelling the cans .... 383

Trials and vexations of a canner's life ; Principal market for canned
tomatoes 384

Catchups ; Tomato catchup 385

Walnut catchup ; Cucumber catchup ; Horseradish catchup . . 387

Currant catchup ; Gooseberry catchup ; Fruit-butter, marmalade, and
jelly; Fruit-butter; Manufacture of apple-butter .... 388

Preparation of raising ; Manner of packing fruit-butter . . . 389

XXX CONTENTS.

PAGE

Marmalade ; Derivation of the term marmalade ; Manufacture of mar-
malade on a large scale . . . .391

Quantity of sugar to be used ; Secret of the great reputation of the pro-
ducts of the principal American factories ; Selection of fruit for mar-
malade 391

Perfumed apple marmalade ; Tutti-frutti; Jelly; Erroneous opinion as
regards the quantity of sugar required for making jelly ; Preparation
of apple jelly without sugar .... 392

Use of the saccharometer in jelly boiling; Preparation of jellies from
pears, mulberries, berries, and other small fruit . . . .393

Preparation of jelly from stone-fruit, quinces, rhubarb, etc. ; French
perfumed jelly ; Manufacture of apple jelly in the largest factory in
Oswego County, New York . . . . . .394

Arrangement of the factory ; Grating the apples and expression of the
juice ; Description of the defecator ...... 395

Object of the defecator ; Description of the evaporator . . . 396

Proper consistency for perfect jelly ; Mode of packing the jelly for
family use ........... 397

Daily product of the factory ; Saving of the apple seeds ; Value of the
apple seeds ; Importance of such institutions . . . . .398

The kettle ; A kettle much used in American preserving establishments,
illustrated and described 399

CHAPTER XXX.

EVAPORATION OF FRUIT.

Great future of this mode of preserving fruit ; Difference between evap-
orated ami dried fruit ......... 400

Evaporating establishments about Rochester, N. Y. ; Value of the an-
nual product of evaporated fruit in the State of New York ; Water
eliminated by the process of evaporation ; Advantage in the cost of
freight of evaporated fruit ; Total export of evaporated and dried
apples from the United States during 1888, and value of the same . 401

Enormous increase of the fruit growing industry in the United States ;
Award of the first prize at the Paris Exhibition of 1 878 to fruit evapo-
rated by the Alden process ; List of articles which are subjected to
evaporation; Advantages of evaporated fruit; Unreliability of
canned goods 402

Experience of the steamer " Rodgers" with canned goods; Principle
upon which the apparatus for evaporating fruit is based, and the
theory of evaporating fruit ..... 403

Absorption of moisture by the air .... 404

Heat alone not sufficient for drying 40

CONTENTS. XXXI

PAGE

Disadvantage of drying fruit in the oven ; Chemical analysis of a parcel
of Baldwin apples, showing the changes effected in the composition
of the fruit by drying in the oven, and by evaporation . . . 406
The Alden apparatus, illustrated and described . . . . . 407
Sun-drying apparatus, illustrated and described . 409

The improved Williams evaporator, manufactured by S. E. Sprout, of

Muncy, Pa., illustrated and described 410

The American fruit evaporator manufactured by the American Manu-
facturing Co., Waynesboro', Pa., illustrated and described . .412
Manner of operating the Alden apparatus ...... 413

Table of intervals at which the trays must be placed in the apparatus ;
Manner of packing evaporated apples ...... 414

Varieties of fruit used and manner of preparing them for evaporation . 415
Various modes of bleaching apples and pears before evaporation ; Treat-
ment of plums after evaporating ; Manner of placing the fruit in the

trays 416

Conversion of grapes into raisins by evaporating ; Preparation of toma-
toes, pumpkins, sweet potatoes, green corn, etc., for evaporation . 417

Manner of evaporating potatoes 418

How evaporated potatoes should be packed ; French method of drying
fruit in the oven . . . . . . . . . .419

Method of drying fruit in the oven practised in central England and in
the New England States 420

CHAPTER XXXI.

PREPARATION OF PICKLES AND MUSTARD.

Manner of packing pickles ; General rules for the preparation of pickles . 420

Preparation of spiced vinegar ; Utensils used in the preparation of
pickles . . 421

" Greening" pickles; List of fruits which are chiefly used for the pre-
paration of pickles in factories ; Barberries ; Beans ; Cabbage, red
and white ; Cauliflower ; Cucumbers ; Elderberry flowers . . 422

English bamboo ; Gooseberries; Mixed pickles ; Mushrooms; Onions;
Peaches; Peas; Picalilly ; Tomatoes; Walnuts . . 423

Mustard ; English method of preparing mustard ; Substances used for
seasoning mustard ; Gumpoldskirchner must-mustard . 424

Moutard des Jesuites ; French mustard ; Ordinary mustard ; Frankfort
mustard; Wine mustard ........ 425

Aromatic or hygienic mustard ; Dusseldorf mustard ; Sour Dlisseldorf
mustard; Sweet Kremser must-mustard; Sour Kremser must-mus-
tard ; Moutard de maille . . . . . .426

Moutarde aux 6pices ; Moutarde aromatis6e ; English mustard . 427

XXXli CONTENTS.

APPENDIX.

PAGE

Table I. Hehner's alcohol table 431

Table II. which indicates the specific gravity of mixtures of alcohol and
water 433

Table III. showing the proportion between per cent, by weight and by
volume of alcoholic fluids at 59 F. 434

Table IV. showing the actual content of alcohol and water in mixtures
of both fluids and the contraction which takes place in mixing . 435

Table V. for comparing the different areometers with Tralles's alcohol-
ometer 436

Determination of the true strengths of spirit for the normal temperature
of59F 437

Table VI. for the determination of the true strengths of spirit for the
normal temperature of 59 F. (15 C.) 439

Table VII. for the determination of the true volume of alcoholic fluids
from the apparent volume at different temperatures ; Explanation of
the table 444

Table VIII. of the preparation of whiskey of various strengths from spirits
of wine ........... 446

Table IX. for the reduction of specific gravities to saccharometer per
cent. . . . . . . . . . . . .447

Table X. for the comparative synopsis of the aerometers for must gene-
rally used ........... 450

Table XI. to Oechsle's aerometer for must ; Table XII. to Massonfour's
aerometer; Table XIII. for comparing per cent, of sugar with per
cent, of extract and the specific gravity . . . . . .451

Table XIV. for determining the content of per cent, of acetic-acid
contained in a vinegar of specific gravity (according to A. C.
Oudemans) ... . . . . . . . . 452

Table XV. for determining the content of per cent, of acetic-acid
contained in a vinegar of specific gravity (according to Mohr) . 453

Table XVI. Comparison of the scales of Keaumur, Celsius, and
Fahrenheit thermometers . . . . . . 454

455

UNIVERSITY

A PRACTICAL TREATISE

ON

THE MANUFACTURE OF VINEGAR, CIDER, AND
FRUIT- WINES;

THE PRESERVATION OF FRUITS AND VEGETABLES BY
CANNING AND EVAPORATION, ETC.

PART I.

THE MANUFACTURE OF VINEGAR.

CHAPTER I.

INTRODUCTION.

ORDINARY vinegar is dilute acetic acid, contaminated with
various vegetable impurities. In this form it has been known
from the earliest times, and its discovery must have immediately
followed that of wine, because it is evident that at the tempera-
ture of the Eastern countries, where the first experiments on the
juice of the grape were made, fermentation must have set in
rapidly, and the wine been quickly transformed into an acid
compound. Moses mentions it and Hippocrates made use of it
as a medicine. Its property of dissolving calcareous earth under
the development of effervescence was known in the earliest times,
and there cau be no doubt that its action upon metal, etc., had
been investigated at a very remote period. Pliny relates how
Cleopatra, by dissolving large pearls in vinegar and drinking the
resulting liquid, won her wager of being able to consume the
value of one million sesterces at one meal ; and Livy and
2

18 VINEGAR, CIDER, AND FRriT-WIXES.

Plutarch state that Hannibal dissolved the rocks impeding his
march across the Alps by ordering his soldiers to pour vinegar
upon them.

Although there can be no doubt that vinegar was in very
general use at an early period, there was until very recently no
definite knowledge as to the cause of its production and the mode
of its formation. The alchemist Gerber, who lived in the eighth
<>entury, was the first to make known the process of increasing
the strength of wine-vinegar by distillation, and Albucases
(about 1100) stated the fact that vinegar to be colorless has to be
distilled over a moderate fire. Basil ins Valentinus, a monk and
celebrated alchemist of the 15th century, knew that by the slow
distillation of vinegar, first a weak product, and then a stronger
one is obtained, and he was probably also acquainted with the
process of obtaining strong acetic acid by distilling copper
acetate (verdigris). In fact for a long time this was the only
mode of preparing acetic acid, the product of the further rectifi-
cation of the liquid being termed radical vinegar, spiritm Veneris,
Venus'* vinegar, spiritm aeruninis, etc.

Stahl and Westendorf were the first to prepare the acid in a
pure state, and Lauranguais, in 1 759, discovered the property of
very strong acetic acid to crystallize at a low temperature.
Loewitz, however, in 1793, was the first to obtain it as a pure
hydrate (glacial acetic acid).

The formation of an acid body in the dry distillation of wood
was already known in the 17th century. However, it was for a
long time not recognized as acetic acid, but considered as a special
acid (pyroligneous acid). Fourcroy and Vauquelin, in 1800,
were the first to recognize this acid as acetic acid, and Thenard,
in 1802, demonstrated the presence of acetic acid among the pro-
ducts formed in the dry distillation of animal substances.

Berzelius, in 1814, determined the exact chemical constitution
of acetic acid, and Saussnre, in the same year, that of alcohol.
Dr. J. Davy observed that spongy platinum, in contact with
vapor of alcohol, l>ecame incandescent and generated acetic acid.
Dobereiner further studied the nature of the acid, and proved
that the alcohol was oxidized at the expense of the' atmospheric
air, producing acetic acid and water, and that no carbonic acid

INTRODUCTION. 19

was formed thus pointing out the fallacy of the opinion held by
the chemists of his time that carbonic acid was one of the pro-
ducts of acetous fermentation.

Schutzeubach, in 1823, one year after the establishment by
Dobereiner of the now generally accepted theory of the formation
of acetic acid from alcohol, introduced the quick process of man-
ufacturing vinegar.

Without detracting from the credit due to Schiitzenbaeh for
the introduction of his method and the improvement in the pro-
cess of the manufacture of vinegar, it may be mentioned that as
early as 1732, nearly a century before, the celebrated Dutch
chemist and physician Boerhaave made known a method for the
fabrication of vinegar from wine, which contained the principles
of the quick process.

Although it is now more than sixty years since the introduc-
tion of Schutzenbach's process into the practice, the manufacture
of vinegar from alcohol remains nearly the same. While no
change can be made as regards the theoretical part of the process,
it being erected upon a foundation clearly indicated by a know-
ledge of natural laws, many important improvements may surelv
be introduced in the manufacture of vinegar on a large scale, this
being especially the case where it is uninterruptedly carried on
with the use of suitable apparatus. Many manufacturers still
work according to Schutzenbach's original plan, i. e., they use an
immense amount of labor for a performance which can be attained
in a much simpler manner.

Progress is necessary in every business, but for several reasons
it is especially necessary for the manufacturer engaged in the
fabrication of vinegar by the quick process. Alcohol in every
form (whiskey, beer, wine) is everywhere subjected to a high tax,
and the constantly increasing taxation of this fundamental
material for the fabrication of vinegar, of course increases the
price the manufacturer has to pay for it. Another reason why
the manufacture of vinegar from alcohol becomes constantly more
difficult is found in the great competition arising from the con-
tinued improvements in the manufacture of pure acetic acid from
wood. Not many years ago it was considered impossible to ob-
tain entirely pure acetic acid from wood when manufacturing on

20 VINEGAR, CIDER, AND FRUIT-WINES.

a large scale, but the article produced at the present time may be
almost designated as u chemically pure" in the true sense of the
word, it containing, besides acetic acid, only water, and the most
accurate analysis cannot detect a trace of the products of tar, which
render unpurified wood vinegar unfit for use.

For consumption on a large scale, especially where only a body
of an acid taste is required, the use of so-called " vinegar essence"
(?'. c., pure 80 to 90 per cent, acetic acid) prepared from wood,
and which, when properly diluted, furnishes ordinary vinegar,
will undoubtedly gradually supersede vinegar prepared from
alcohol, it being considerably cheaper. And notwithstanding
that the price of vinegar essence is decreasing every year, in
regions where wood is plentiful and cheap, its manufacture is a
well-paying industry on account of the many valuable by-products
(tar, wood-spirit, charcoal) obtained besides acetic acid. Even at
the present time for all industrial purposes where acetic acid is
required, as, for instance, in the manufacture of tar colors, that
obtained from wood is used, and the quantities consumed in the
fabrication of table vinegar become larger every year.

But the manufacture of vinegar from alcohol and alcoholic fluids
will nevertheless continue to flourish because the product obtained
from them actually possesses different properties from the pure
acetic acid prepared from wood. Vinegar obtained from pure
alcohol, and, still more so, that from fermented fruit juices, as
wine, cider, skins of pressed grapes, or from malt, contain, besides
acetic acid and water, small quantities of bodies, which on account
of their being analogous to those occurring in wine, may be
designated as u bouquet-bodies," and which give to the vinegar
an agreeable smell and taste entirely wanting in acetic acid pre-
pared from wood. These properties are so characteristic that any
one gifted with a sensitive and practised sense of smell can at
once distinguish pure acetic acid vinegar from that prepared from
wine, cider, beer, etc.

By the addition of volatile oils or compound ethers an agree-
able odor can, of course, be imparted to vinegar obtained by
diluting pure wood acetic acid with water, but it is impossible to
produce the harmonious bouquet peculiar to vinegar prepared
from alcohol or fruit juices, a similar relation existing here as

THEORY OF THE FORMATION OF VINEGAR. 21

between wine and so-called artificial wine. The latter can he
made so as nearly to approach, as regards taste and smell, genuine
wine, but a connoisseur will at once detect the difference.

The principal defects of the process of manufacturing vinegar
by tEe quick process in general use are not in the method itself,
for that, as already indicated, corresponds entirely to the theoreti-
cal conditions, and yields as good a product as can be obtained
from the raw material used. The weak point of the process is
found in the practical execution of it : the losses of material are
much more considerable and greater than are absolutely necessary,
the consumption of labor is very large, and, as every manufacturer
knows from experience, interruptions in the regular process of
working are of too frequent occurrence.

All these disadvantages can be reduced to a minimum, if not
absolutely overcome, and it is hoped sufficient hints how this can
be done will be found in the following chapters.

CHAPTER II.

THEORY OF THE FORMATION OF VINEGAR.

INDEPENDENTLY of the formation of acetic acid by the so-
called dry distillation, the chemical processes by which acetic acid
in larger quantities is formed are at present quite well understood,
and will be briefly explained as follows :

As previously mentioned, Dobereiner, in 1822, established the
theory of the formation of acetic acid from alcohol, and the pro-
cesses taking place thereby may be expressed by the following
formula :

C 2 H C + 2 = C 2 H 4 2 + H S

Alcohol. Oxygen. Acetic acid. Witter.

According to the above formula, acetic acid and water are
formed by the action of oxygen upon alcohol, and hence the for-
mation of acetic acid takes place by a partial combustion or
oxidation of the latter. Alcohol and acetic acid are, however,
only two members of the process, and that, besides the latter,

22 VINEGAR, CIDER, AND FRUIT-WINES.

other bodies are formed from the alcohol can be readily detected
in a vinegar manufactory by the sense of smell.

By treating alcohol with pyrolusite and sulphuric acid hence
by the action of oxygen at the moment of its liberation from a
combination (in its nascent state) Dobereiner obtained a body
which he called "light oxygenated ether" (leichter Sauer-
stoffather). Liebig, later on, studied the nature of this com-
bination more accurately, and found that, as regards its composi-
tion, it differed from that of alcohol only by containing two
atoms less of hydrogen. He applied to it the term " aldehyde."

Aldehyde is composed of C 2 H 4 O, and its formation is repre-
sented by the formula

C 2 H G + <> = C 2 H 4 + H 2

Alcohol. Oxygen. Aldehyde. Water.

In the examination of the properties of aldehyde it was shown
that it is readily converted into acetic acid by the absorption of
oxygen, and, based upon these facts, Liebig established a theory
of the formation of vinegar which was for many years considered
correct.

Essentially Liebig's theory is as follows :
By the exposure, under suitable conditions, of alcohol to the
action of the atmospheric oxygen, one-third of the entire quantity
of hydrogen contained in it is withdrawn, and aldehyde is formed.
The latter, however, immediately further combines with oxygen,
and is converted into acetic acid; the formation of vinegar from
alcohol being, therefore, a partial process of combustion.

From the present stand-point of our knowledge as regards the
formation of acetic acid from alcohol, the correctness of this
theory is about parallel with that according to which alcohol and
carbonic acid are formed by the alcoholic fermentation of sugar.
This latter process can also be illustrated by an equation in as
simple a manner as the conversion of alcohol into acetic acid by
aldehyde. At the present time the processes taking place in the
formation of acetic acid from alcohol must, however, be considered
as far more complicated than supposed by Liebig. According to
the latter, a simple oxidation, i. e., a simple chemical process,
takes place; but, according to the now universally accepted view,
the formation of vinegar is due to a cheniico-physiological pro-

THEORY OF THE FORMATION OF VINEGAR. 23

cess with the cooperation of a living organism. Alcohol and
oxygen alone do not suffice for this purpose, the presence of nitro-
genous bodies and salts, besides that of an organism, being abso-
lutely necessary.

The French chemist, Pasteur, was the first to establish the
formation of vinegar as a peculiar process of fermentation, and
he maintains that a certain organism, the "vinegar ferment' 7 or
" vinegar yeast/' consumes the alcohol, nitrogenous substances and
salts, and separates acetic acid, aldehyde, etc., as products of the
change of matter taking place in the living organism. On the
other hand, the German chemist, Nageli, is of the opinion that
the role of the organism is to bring the particles of the substance
to be fermented (in this case, alcohol) lying next to it, into such
vibrations as to decompose them into more simple combinations
in this case, acetic acid, aldehyde, etc.

The scientific dispute over these two different views is not yet
settled, though the majority of chemists are inclined to accept
Pasteur's theory. For the practical man it is of no consequence
which of these views will be finally accepted as the correct one ;
the fact that the process of the formation of vinegar is connected
with the living process of an organism is alone of imporauce to
him.

As is well known, organisms producing fermentation are named
after certain products which they form in larger quantities, the
organism forming alcohol from sugar being, for instance, briefly
termed " alcoholic ferment." In this sense we may also speak
of a vinegar or acetous ferment, since a definite organism causing
the formation of larger quantities of acetic acid from alcohol is
known, and the cultivation of this ferment is one of the principal
tasks of the manufacturer of vinegar.

Numerous observations have established the fact that the pro-
perties of forming large quantities of acetic acid are inherent
only in this ferment. Small quantities of acetic acid are, how-
ever, also constantly formed by other ferments, so that in examining
products due to the process of decomposition induced by organ-
isms, acetic acid will be generally found among them. In the
alcoholic fermentation, at least in that of wine and bread-dough,
acetic acid is always found. It originates in the germination of

24 VINEGAR, CIDER, AND FRUIT-WINES.

many seeds, and generally ap|>ears in the putrefaction of sub-
stances rich in nitrogen, such as albumen, glue, etc. It appears
also in the so-called lactic fermentation, the lactic acid formed by
the specific ferment of this species of fermentation being by
further processes of fermentation decomposed into butyric and
acetic acids.

Acetic acid, belonging to those bodies which may be considered
as quite far advanced products of oxidation of higher compound
combinations, its occurrence in living organisms is not remarkable.
It is found in many fluids of animal origin, for instance, in meat-
juice, milk, sweat, and urine. It also occurs constantly in the
fresh fruit of the tamarind. What processes take place in its
formation in these cases are not known, though it is very likely
directly formed from certain varieties of sugar. Just as little do
we know about the origin of the acetic acid found in the mineral
water of Briickenau. 1

There is quite a large series of chemical processes in which
certain quantities of acetic acid are always formed. Sugar, starch,
woody fibre, and, in general, all compounds known as carbohy-
drates, when fused with caustic alkalies, always yield certain
quantities of acetic acid, as also by themselves when subjected
to destructive distillation.

Among the processes by which acetic acid is produced in a
purely chemical manner, /. r., without the cooperation of organ-
isms, the most interesting is that by which itvS formation is effected
by the action of very finely divided platinum (the so-called plati-
num black) upon alcohol. Platinum black is easily prepared by
boiling a solution of platinic chloride with an addition of an
excess of sodium carbonate and a quantity of sugar until the
precipitate, formed after a little time, becomes perfectly black and
the supernatant liquor colorless. The black powder is collected
on a filter, washed and dried by gentle heat. From its minute
state of division this substance condenses within it several hun-
dred times its volume of oxygen ; consequently, when the vapor
of alcohol comes in contact with it, a supply of oxygen in a
concentrated state is presented to it, and the platinum, without

1 Free acetic acid is also claimed to occur in the water of a river of Brazil.

THEORY OF THE FORMATION OF VINEGAR.

25

losing any of its inherent properties, effects chemical combination,
the alcohol undergoing slow combustion, and being converted into
acetic acid. In order that the reaction may continue, it is, of
course, necessary to present fresh oxygen to the platinum to re-
place that which is withdrawn. The two actions then go on
side by side.

This can be illustrated by an apparatus similar to Fig. 1. It
consists of a bell glass through the mouth of which a long funnel
passes ; the lower end of this funnel terminates in a fine point,
so that the alcohol poured in may
percolate very slowly. The vessel
is placed upon supports within a
dish in which is a saucer or small
flat basin containing the platinum
black. The interstice between the
bottom of the dish and the bell
serves for the circulation of air in
the jar. On pouring the alcohol
through the funnel, in the course of
a short time the odor of acetic acid
is perceived at the mouth from the
acetic acid vapors, which are gene-
rated. These condense on the sides
of the jar and trickle to the bottom,
where they collect in the vessel in
the dish. It is advantageous for the

success of the experiment to have the alcohol heated to about 90
F. when it is poured in. By washing and glowing the platinum
used for the oxidation of alcohol, it can be again employed for
the same purpose.

Independently of the purely chemical methods which, with the
exception of that by which acetic acid is produced by the dry
distillation of wood, are of no practical importance, the forma-
tion of vinegar, no matter what method may be adopted, can only
be effected in the presence of certain organisms. It has long
been known that organisms to which the term mother of vinegar
has been applied,- develop upon fluids containing, besides alcohol,
certain other substances, for instance upon weak wine and beer,

26 VINEGAR, CIDER, AND FRUIT-WINES.

and this mother of vinegar has also been used for the fabrication
of vinegar on a large scale. To Pasteur, however, belongs the
incontestable merit of having more accurately examined the rela-
tions of these organisms to the formation of vinegar. These
examinations gave rise to his experiments on the diseased altera-
tion of wine, which were later on succeeded by his researches on
the formation of wine vinegar.

Pasteur found that upon the surface of every fluid capable by
reason of its composition of being converted into vinegar, organ-
isms develop immediately after the commencement of the forma-
tion of vinegar. He recognized these organisms as fungoid plants
of a low order and called them Mycoderma aceti. More recent
researches on the botanical nature of these plants show them to
belong to the group of lowest fungoid organisms to which the
term bacteria or schizomycdes has been applied.

These plants consist of a single, generally globular or filiform
cell, their special characteristic; being their mode of propagation,
which is effected by the division of the cell into two and then a
separation or splitting of both.

The exceedingly minute size of the schizomycetes and their
great resemblance to each other make their accurate determina-
tion very difficult, and, hence, it is customary to name the better
known species in accordance with the chemical products they
form or in accordance with the phenomena they produce. Among
the first kind may be classed those which effect the formation of
acetic, lactic, butyric acids ; other very little known bacteria must
be considered as the cause of the so-called nitric acid fermenta-
tion, and again others appear in putrid fermentation. A special
group of bacteria reaches development in animal organisms and
give rise to terrible diseases, some causing rinderpest, others tuber-
culosis, and various other maladies. Cholera and other epidemics
have also recently been found to be due to certain bacteria.

The bacteria causing disease are of course very interesting to
the physician ; but to the manufacturer of vinegar a thorough
knowledge of the conditions of life governing the vinegar bacteria
is of the utmost importance, in order to conduct the fabrication
in such a manner that disturbances shall rarely occur, and, should
they happen, that he may be able readily to remove them. It may,

VINEGAR FERMENT AND ITS CONDITIONS OF LIFE. 27

therefore, be said that the entire art of the manufacture of vinegar
consists in an accurate knowledge of the conditions of life of the
vinegar bacteria and in the induction of these conditions of life.
As long as the latter are maintained, the process of the formation
of vinegar will go on without disturbance and the origination of
new generations of vinegar ferment be connected with the con-
version of certain quantities of alcohol into vinegar.

CHAPTER III.

THE VINEGAR FERMENT AND ITS CONDITIONS OF LIFE.

A. The Vinegar Ferm,ent.

XOTHING is as yet known about the origin of the vinegar
bacteria, but experiments have shown these organisms to be every-
where distributed throughout the air and to multiply at an enor-
mous rate when fluids of a composition suitable for their nour-
ishment are presented to them. A fluid especially adapted for
this purpose is, for instance, thoroughly fermented, ripe wine, its
exposure in a flat vessel and at the ordinary temperature of a
room being sufficient to induce the augmentation of the vinegar
bacteria reaching it from the air.

This experiment is, however, only a certain success when exe-
cuted with ripe wine, by which is meant wine which shows but
little turbidity when strongly shaken in contact with air and
exposed in a half-filled bottle to the air. Young wine contains a
large quantity of albuminous substances in solution, and is espe-
cially adapted for the nourishment of an organism (saccharomyces
mesembryanthemum) belonging to the saccharomycetes. It develops
upon the surface of such wine as a thick white skin w r hich later
on becomes wrinkled and prevents the growth of the vinegar
ferment. A fluid well adapted for the nourishment of the vine-
gar ferment, and which may be used as a substitute for wine for
its cultivation, is obtained by adding 5 to 6 per cent, of alcohol
and about J per cent, of malt extract to water.

28 VINEGAR, CIDER, AND FRUIT-WINES.

By exposing ripe wine or the last-mentioned fluid at the ordi-
nary temperature of a room, and best in a plate covered by a
glass plate resting upon small wooden blocks to prevent the access-
of dust, the formation of a thin veil-like coating upon the surface,
which shortly covers the entire surface, will, in a few days, be
observed. The wine soon shows the characteristic odor and taste
of acetic acid, and in a few days assumes a somewhat darker
color and deposits a slight, brownish sediment consisting of decayed
vinegar ferment. In 14 to 21 days the fluid is entirely converted
into vinegar, i. c., it contains no more alcohol, but instead the
corresponding quantity of acetic acid.

By exposing the vinegar thus obtained for a longer time to the
air, a thick white skin of mold may happen to form on the surface,
and, on chemically examining the fluid, the content of acetic acid
will be found steadily to decrease, the mold which is able to convert
the alcohol into water and carbonic acid possessing also the power
of forming the same products from acetic acid.

The above-described process of the destruction of the wine and
its conversion into vinegar by a veil-like coating of the vinegar
ferment occurs most frequently ; a thick spume, the so-called
'mother of vinegar, may, however, also happen to form upon the
surface, a phenomenon to which we will refer later on.

On examining under the microscope a drop taken from the
surface of the wine when the veil of vinegar ferment commences
to form, a picture like that shown in Fig. 2 presents itself. In
a somewhat more advanced stage the formations resembling
chains and strings of beads appear more frequently, and when
finally the development of the ferment is in full progress, it
appears as an aggregation of numerous single cells mixed with
double cells and many other cells strung together like beads.
The field of vision of the microscope is then completely filled
with a large number of colorless globules, which are present
either singly or in combination of twos, the formations resem-
bling chains or strings of beads occurring but seldom. In many
of the separately-occurring formations oval forms generally
slightly contracted in the centre are observed ; this contraction
indicates the place where the splitting of one cell into two new
cells takes place. By strongly shaking the fluid before viewing

VINEGAR FERMENT AND ITS CONDITIONS OF LIFE. 29

it under the microscope, very few of the above-mentioned bead-
like formations will be found, but more frequently the contracted
ones. By observing for hours a drop of the fluid containing the
ferment in an advanced state of development, the globules strung
together will be noticed to fall apart when at rest. Hence it may
be supposed that in the augmentaHon of cells by splitting, the
newly formed cells adhere together up to a certain stage, and
later on separate in the fluid when in a quiescent state. Like

Fig. 2.

Development of the Vinegar Ferment. The ferment is young but in full activity.

X 500.

every other organism the vinegar ferment only lives for a certain
time, and after dying, sinks below the fluid and forms upon the
bottom of the vessel the above-mentioned sediment. The latter
appears under the microscope in the same form as the living fer-
ment, but differs from it in being less transparent and of a
brownish color. The augmentation of the vinegar ferment takes
place very rapidly, and it will be found in a few hours after the
commencement of its development in all stages of life upon the
surface of the fluid, it being possible to distinguish cells of from
1.5 to 3.5 micromillimetres in size. 1

The vinegar ferment requiring /ree oxygen for its augmentation

1 One micromillimetre = v millimetre.

30 VINEGAR, CIDER, AND FRUIT-WINES.

can exuberantly grow only upon the surface of the nourishing
fluids. By filling a bottle about four-fifths with wine, and after
allowing the vinegar ferment to develop, closing the mouth of the
bottle with the hand and submerging the neck of the bottle in
water, the fluid will be seen to rise for some time in the bottle
and then remain stationary. A determination of the content
of acetic acid immediately before the commencement of this ex-
periment, and a few days after, shows but a slight increase of
acetic acid, because after the. ferment has consumed the free oxygen
present in the bottle, the essential condition for its further develop-
ment is wanting, and it must cease its activity without, however,
perishing. It may here be remarked that the vinegar ferment,
like the majority of bacteria, possesses an extraordinary vitality ;
under unfavorable conditions it passes into a kind of quiescent
state, during which no perceptible increase of cells takes place.
It may remain in this state for a long time without suffering
destruction, and recommences augmentation and propagation in a
normal manner as soon as the conditions required for its nourish-
ment are again presented.

The great rapidity of the augmentation of the vinegar bacteria
can be shown by an experiment of some importance to the prac-
tice. Pour into a shallow vat of about three feet in diameter a
fluid suitable for the nourishment of bacteria, and divide upon
the surface by means of a thin glass rod small drops of wine, upon
which the frequently mentioned veil has been formed. In a few
hours the entire surface of the fluid in the vat will be covered
with vinegar bacteria, spreading concentrically from the points
where the drops of wine have been distributed. From this it will
be seen that the cultivation of the ferment for the purpose of
manufacturing vinegar offers no difficulties, provided all con-
ditions required for the propagation of this organism be observed.

B. Now*wkmy conditions of the vinegar ferment.

.Through many observations and experiments made in practice
the conditions most favorable for the development of the vinegar
ferment, and for converting in the shortest time the largest quan-
tity of alcohol into acetic acid have been determined. These con-

VINEGAR FERMENT AND ITS CONDITIONS OF LIFE. 31

ditions will first be briefly enumerated and then the separate
points more fully discussed.

For the vinegar bacteria to settle upon a fluid, and for their
vigorous augmentation the following factors are required :

1. A fluid, which, besides alcohol and water, contains nitro-

genous bodies and alkaline salts. The quantities of these
bodies must, however, not exceed a certain limit.

2. The fluid must be in immediate contact with oxygen (at-

mospheric air).

3. The temperature of the fluid and the air surrounding it

must be within certain limits.

As regards the composition of the nourishing fluid itself, it
must contain all the bodies required for the nourishment of a
plant of a low order. Such substances are carbohydrates, albu-
minates, and salts. Alcohol must be named as a specific nourish-
ment of the vinegar ferment, provided the supposition that the
latter consumes the alcohol and separates in its place acetic acid
is correct. The quantity of alcohol in the fluid intended for the
fabrication of vinegar must, however, not exceed a certain limit,
a content of 15 per cent, appearing to be the maximum at which
acetous fermentation can be induced. But even a content of 12
to 13 per cent, of alcohol is not very conducive to the vegetation
of the vinegar ferment, and every manufacturer knows the diffi-
culty of preparing vinegar from such a fluid. Like a high con-
tent of alcohol, a large quantity of acetic acid in the nourishing
fluid exerts also an injurious influence upon the vinegar ferment.
Upon a fluid containing 12 to 13 per cent, of acetic acid, and 1
to 2 per cent, of alcohol, the ferment vegetates only in a sluggish
manner, and considerable time is required to convert this small
quantity of alcohol into acetic acid.

That the vinegar ferment cannot live in dilute alcohol alone
may be shown by a simple experiment. By placing fully developed
ferment upon a fluid consisting of only water and alcohol, a very
small quantity of acetic acid is formed, but the ferment perishes
in a short time it starves to death. A fluid suitable for the
nourishment of the ferment must therefore contain the above-
mentioned nourishing substances, sugar, dextrine, or similar com-
binations occurring in wine, malt extract, beer, being generally

32 VINEGAR, CIDER, AND FRUIT-WINES.

employed as carbohydrates. These fluids further contain nitro-
genous combinations which may serve as nutriment for the
ferment, and also considerable quantities of phosphates. Hence
by an addition of wine (or must), malt extract, beer, or any fruit
wine (apple or pear cider) to a mixture of alcohol and water, a
fluid can be prepared, which contains all the substances essential
to the nourishment of the ferment.

The quantity of these nourishing substances, as compared with
that of alcohol, is very small, the quantity by weight of vinegar
ferment required for the conversion of a very large amount of
alcohol into vinegar being only a few fractions of one per cent, of
weight of alcohol used. Hence the manufacturer may be very
economical with the addition of nourishing substances to the fluid
to l>e converted into vinegar without having to fear that the fer-
ment will be stinted.

The vinegar ferment is very sensitive to sudden changes in the
composition of the fluids upon which it lives and suffers injury
by such changes which is recognized by diminished propagation
and decreased conversion of alcohol into acetic acid.

By bringing, for instance, vinegar ferment which vegetated in
an entirely normal manner upon a fluid containing only 4 to 5
per cent, of alcohol, upon one with a content of 10 to 11 per
cent., its augmentation, as well as fermenting energy, decreases
rapidly and remains sluggish until a few new generations of cells
have been formed which are better accustomed to the changed
conditions. By bringing, on the other hand, a ferment from a
fluid rich in alcohol upon one containing a smaller percentage the
disturbances in the conditions of the ferment can also be observed,
but they exert a less injurious influence upon the process of the
formation of vinegar than in the former instance.

The process of nourishment of the vinegar ferment must, how-
ever, not be understood to consist simply in the consumption of
sugar, albuminates, and salts. It differs according to the compo-
sition of the nourishing fluid, and is so complicated as to require
a very thorough study for its explanation. If, for instance, wine
is converted into vinegar, and the composition of the latter com-
pared with that of the original wine, it will be found that not
only the alcohol has been converted into acetic acid and the fluid

VINEGAR FERMENT AND ITS CONDITIONS OF LIFE. 33

has suffered a small diminution of extractive substances and salts,
which might be set down to the account of the nourishment of
the ferment, but that the quantity of tartaric, malic, and succiuic
acids has also decreased as well as that of glycerine, and of the
latter even nothing may be present. Hence it must be supposed
that the vinegar ferment also derives nourishment from these sub-
stances, or that its fermenting activity acts upon them as well as
upon the alcohol. There is finally the very important fact for
the practice, which has not yet been sufficiently explained, that
the vinegar ferment develops more rapidly upon a fluid which,
besides the requisite nourishing substances, contains a certain
quantity of acetic acid, than upon a fluid entirely destitute of it..
Regarding the supply of air, it may be said that, while for mere
existence the vinegar ferment requires comparatively little air,
large quantities of it are necessary for its vigorous augmentation
and fermenting activity. In the practice it is aimed to accom-
plish this by exposing the fluid in which the ferment lives in thin
layers to the action of the air, and, in fact, upon this the entire
process of the quick method of fabrication is based.

Besides the above-mentioned factors the temperature to which
the ferment is exposed takes an important part as regards its
development. The limits at which the augmentation of the fer-
ment and its vinegar-forming activity are greatest, lie between
H8 and 95 F. Above this limit the formation of vinegar
decreases rapidly and ceases entirely at 104 F. By again
reducing the temperature to 86 F. the ferment reassumes its
activity. At a temperature exceeding 104 F. the ferment suffers
perceptible injury ; heated to 103 F. it becomes sensibly weaker,
and at first augments very slowly, regaining its original vigorous
development only after several generations. By raising the tem-
perature of the fluid to 122 F. the ferment perishes.

To low temperatures the ferment seems to be less sensitive.
By lowering the temperature of a fluid showing an exuberant
growth of ferment to 50 F. or less, the formation of vinegar
continues, though at a very much reduced rate. Experiments
especially made for the purpose have shown that by exposing
wine with a growth of ferment to a temperature of 14 F. so
that it was converted into ice, the ferment recommenced to grow
3

34 VIXEGAR, CIDER, AND FRUIT-WINES.

and to form acetic acid after melting and heating the fluid to 59
F. It should, however, be expressly stated that while vinegar
ferment in a state of development keeps up a slow growth when
the fluid is reduced to a low temperature, it is very difficult to
rear it upon a cold fluid. This is very likely the reason why
acetous degeneration is not known in cold wine cellars, while in
those having a temperature of over 59 F. this dreaded process
can only be guarded against by the greatest care. .

Since the augmentation of the ferment and its fermenting
activity increase with a higher temperature, it would appear most
suitable to keep the temperature of the fluid to be converted into
vinegar as near the uppermost limit of 95 F. as possible. Ex-
perience, however, has shown that at this temperature disturb-
ances are of frequent occurrence in the generators, and for this
reason one of 86 to 89 F. is generally preferred. The process
of the formation of vinegar itself explains why disturbances may
easily occur at a high temperature. It is a chemical (oxidizing)
process in which a certain quantity of heat depending on the
quantity of alcohol to be oxidized within a certain time is always
liberated. If now by the use of a temperature close to 95 F.
the activity of the ferment is strained to the utmost, a large quan-
tity of alcohol is in a short time converted into acetic acid, and
consequently so much heat is liberated that the temperature in the
generator rises above the permissible maximum and the ferment
immediately ceases its activity. Thus it may happen that in a
generator which has satisfactorily worked for some time, the for-
mation of vinegar ceases all at once, and on examining the ther-
mometer placed on the apparatus the cause will be generally found
to be due to too high a temperature.

Mother of Vinegar.

In connection with the description of the conditions of life of
the vinegar bacteria, a peculiar formation, playing in many cases
a role in the practice of the fabrication of vinegar, has to be
mentioned. This is the so-called mother of vinegar, the term
having very likely been applied to it on account of its causing

VINEGAR FERMENT AND ITS CONDITIONS OF LIFE. 35

acidification when brought into a fluid suitable for the formation
of acetic acid.

The mother of vinegar occurs generally only in fluids which,
besides alcohol, contain large quantities of extractive substances,
for instance, wine or beer. After the ordinary vinegar ferment
has for some time grown upon the surface of these fluids a coat-
ing is formed which acquires a thickness of up to j- inch, and
such consistency, that with some care, it can be lifted as a cohe-
rent mass from the fluid. The mother of vinegar then represents
a very elastic transparent mass of a yellowish-white color and
closely resembles an animal hide swelled to a high degree by treat-
ment with water.

Upon the side of the skin exposed to the air numerous molds
frequently settle and form complete sods of the well-known gray
green or yellow color. This is, however, only a secondary phe-
nomenon, the mother of vinegar being especially adapted as a
basis for the development of molds. By exposure to the air, best
upon a porous support (a plate of brick or gypsum), the mother
of vinegar quickly decreases in bulk and finally dries to a very
thin layer resembling paper. Viewed under the microscope the
mother of vinegar appears as a mass entirely devoid of structure
in which numerous individuals of the vinegar ferment are
imbedded.

Several opinions have been expressed as to the nature of the
mother of vinegar, and among others that it is a special variety
of vinegar ferment, w r hich, however, cannot be accepted as correct,
it being far more probable that its formation depends on the
nature of the fluid upon which ordinary vinegar ferment grows.
As previously mentioned, the mother of vinegar reaches develop-
ment upon young wine and beer, and these fluids always contain
certain quantities of albuminous substances in solution. Now it
is very probable that the mother of vinegar consists of pecu-
liarly changed albuminous substances eventually also of carbo-
hydrates and that innumerable organisms of the vinegar ferment
are distributed throughout the mass which cause the acidification
of fluids to which it is transferred. This view is supported by
its composition, with regard to its organic substance, as deter-
mined by Mulder.

36 VINEGAR, CIDER, AND FRUIT-WINES.

Composition of the mother of vinegar, according to Mulder :

Carbon 46 - 8

Hydrogen ....-' 6 - 4

Nitrogen 3 - 9

Oxygen 42< ^

According to R. D. Thomson, who also examined the mother
of vinegar, its composition is :

Organic substance .{ C ^ lul Se } about 5 per cent.

I al lin-ini nrtim snhstaiioe t

'I albuminous substance
J potash, lime
I phosphoric acid
Water ..... more than 94

salts . . . i*: ;' - ., "

These analyses justify the opinion that albuminous substances
as well as carbohydrates participate in the formation of the mother
of vinegar. (In beer carbohydrates are always present, while in
wine extractive substances occur which, at least, are closely allied
to the carbohydrates.) An experiment especially made for the
purpose conclusively proves that the formation of the mother of
vinegar depends on the presence of the above-mentioned sub-
stances in the fluid upon which it grows.

A thick cover of mother of vinegar had formed upon young
wine ; this being removed it was in a few days replaced by a new
growth, which, however, was not quite so thick. This cover
being also removed a third but very slight one was formed until
finally a cover of mother of vinegar was no longer developed
upon the fluid, but only normal vinegar ferment. The explana-
tion of this phenomenon is that with the decrease of nitrogenous
substances in the wine, the conditions for the development of
mother of vinegar became constantly more unfavorable until
finally nothing but vinegar ferment could form. By transferring
a piece of mother of vinegar to a fluid composed of alcohol, water,
and some old wine (hence such as contained only very small quan-
tities of nitrogenous substances) the slimy mass remained floating
in the fluid without increasing or undergoing alteration, while the
surface became covered with ordinary vinegar ferment and acidi-
fication proceeded in a normal manner.

The formation of mother of vinegar can always be successfully
attained by exposing young wine to the air until the commence-

VINEGAR FERMENT AND ITS CONDITIONS OF LIFE. 37

ment of the formation of mold is indicated by the appearance of
white dots and then transferring the wine to a room having a
temperature of 86 F. At this temperature the development of
the vinegar ferment proceeds so vigorously that it suppresses the
mold ferment, and the peculiar mass constituting the mother of
vinegar soon forms upon the surface.

Mother of vinegar occurs so generally in young wine (which
is chiefly used for the preparation of wine vinegar) that its for-
mation was considered as inseparably connected with that ot
acetic acid from alcohol, while actually it is only due to the pecu-
liar constitution of the fluid to be converted into vinegar. In
many places this opinion is still entertained, and especially where,
as is generally the case, the manufacture of vinegar from wine is
yet carried on in the primitive way of centuries ago. In speaking
of the preparation of vinegar from wine, it will be shown that the
conversion can be effected by means of the ordinary vinegar
ferment without the appearance of mother of vinegar.

Summary.

Briefly stated the points of the theoretical conditions of the
formation of vinegar of importance to the manufacturer are :

1. Acetic acid is formed during many chemical conversions;

for the manufacture of acetic acid, and consequently of
vinegar on a large scale, only two methods are available,
viz., the preparation of vinegar from alcohol by fermenta-
tion, or the obtaining of acetic acid by dry distillation of
wood.

2. All alcoholic fluids formed by vinous fermentation of saccha-

riferous plant juices or fermented malt extracts are suitable
for the preparation of vinegar by fermentation. Specially
prepared mixtures of water, alcohol, and vinegar may
also be used for the purpose, provided they contain small
quantities of certain organic substances and salts, and not
over 14 per cent, of alcohol.

3. The acetous fermentation is induced by a microscopic organ-

ism belonging to the bacteria, and the conversion of the
alcohol into acetic acid is in a certain ratio to the aug-
mentation of this organism.

38 VINEGAR, CIDER, AND FRUIT-WINES.

4. Besides the substances mentioned in 2, the vinegar ferment

requires for its vigorous development free oxygen and a
temperature lying between 68 and 95 F.

5. In the acetous fermentation the greater portion of the alcohol

is converted into acetic acid and water ; besides these small
quantities of other products are formed which are partially,
not yet thoroughly, known. In the conversion of wine,
beer, etc., other combinations contained in the fluids,
besides alcohol, are also essentially changed.

CHAPTER IV.

PRODUCTS OF ACETOUS FERMENTATION.

THE formation of vinegar by fermentation being a chemico-
physiological process, many and complicated chemical processes
must take place in the fluid to be converted into vinegar in order
to produce all the combinations required for the augmentation of
the ferment. Attention cannot be too frequently called to the
fact that from the standpoint of the manufacturer, the regular
augmentation of the ferment is the main point of the entire fab-
rication, the quick conversion of the alcohol contained in the fluid
being a necessary consequence of it.

The body of the ferment, however, contains cellulose, albu-
minous substances, very likely fat and other combinations not yet
known, all of which must be formed from the nourishing sub-
stances (sugar, dextrine, albuminous substances, etc.), present.
It being very probable that a portion of the alcohol contained in
the fluid is consumed for this purpose, a small but nevertheless per-
ceptible loss of alcohol will occur in the fabrication. It would
be erroneous to suppose that the conversion of alcohol into acetic
acid and water is effected according to the Formula given on p. 21 ;
a certain portion of it is always converted into other combinations,
the nature and formation of which can only be, to a certain extent,
explained.

In the vinous fermentation, which of all fermenting processes

PRODUCTS OF ACETOUS FERMENTATION. 39

has been most thoroughly studied, we find that besides alcohol
and carbonic acid large quantities of glycerin and succinic acid
and probably other bodies are formed from the sugar, which must
undoubtedly be classed among the products of vinous fermenta-
tion. Similar processes, no doubt, take place in the acetous fer-
mentation, and besides acetic acid and water other little known
products of fermentation are regularly formed.

According to the nature of the sacchariferous fluids subjected
to vinous fermentation small quantities of certain bodies called
fusel oils are formed which are decidedly products of fermenta-
tion. They impart to the fermented fluid, as well as to the alcohol
distilled from it, such characteristic properties that from the odor
of the alcohol a correct judgment can be formed as to the material
employed in its preparation.

In the conversion of such a fluid, or of alcohol prepared from
it, into vinegar, the fusel oils are also changed very likely oxi-
dized and with some experience the material (wine, beer, malt,
etc.), from which the vinegar has been made can be determined
by the sense of smell. The quantities of aromatic substances
which reach the vinegar in this manner are, of course, very small,
but they must nevertheless be classed among the most important
products of acetous fermentation, they being very characteristic
as regards the nature of the vinegar. Of the products of acetous
fermentation, besides acetic acid, aldehyde and acetal are best
known, these combinations appearing always, even if only in
small quantities, in the fabrication of vinegar according to the
methods customary at the present time.

Acetic Aldehyde or Acetaldehyde.

Acetic aldehyde, commonly called simply aldehyde (from alcohol
dehydrogenatum), is obtained by oxidizing spirits of wine by
means of manganese dioxide (pyrolusite) and sulphuric acid,
chromic acid, or platinum black, in the presence of air, or if alcohol
or ether is burning without a sufficient supply of air. It is also
formed by heating a mixture of acetate and formate of calcium.
It is contained in considerable quantities in the first runnings
obtained in the manufacture of spirit of wine.

40 VINEGAR, CIDER, AND FRUIT-WINES.

To prepare pure aldehyde 3 parts of potassium clichromate in
small pieces are placed in a flask surrounded by a freezing mix-
ture and a well-cooled mixture of 2 parts of spirit of wine, 4 of
sulphuric acid, and 4 of water added. After connecting the flask
with a condenser the freezing mixture is removed ; a violent reac-
tion soon sets in and the liquid begins to boil. The vapors have
first to pass through an ascending tube surrounded by warm water
at about 122 F. Alcohol and different products are condensed
and flow back while the vapor of the aldehyde, after having
passed through a descending condenser, is absorbed in anhydrous
ether.

Pure aldehyde thus obtained is a colorless liquid of the com-
position C 2 H 4 O. Its specific gravity is 0.800, and it boils at
about 71.5 F. It has a pungent and suffocating smell and is
readily soluble in water, alcohol, and acetic acid. Like all the
aldehydes it is very easily oxidized and acts, therefore, as a pow-
erful reducing agent. Thus, on heating it with a little ammonia
and nitrate of silver, metallic silver separates out, coating the
sides of the vessel with a bright mirror. It combines with ammo-
nia and forms a crystalline compound which has a peculiar smell
of mice.

Though it is likely that in the fabrication of vinegar by the
quick process, besides aldehyde, acetic and formic ethers are
formed, they are of comparatively little importance for our pur-
poses. Of more importance, however, is acetal, the formation of
this combination affording an interesting insight into the compli-
cated processes accompanying the conversion of alcohol into acetic
acid.

Acetal.

This combination is best prepared by distributing pieces of
pumice, previously moistened with 25 per cent, alcohol over a
large glass plate, placing watch crystals containing platinum black
upon the pieces of pumice and covering the whole with a large
bell-glass. The alcohol absorbed by the pumice being converted
into acetic acid, 60 per cent, alcohol is poured upon the plate and
the air in the bell-glass from time to time renewed. In a few

PRODUCTS OF ACETOUS FERMENTATION. 41

weeks a quite thick fluid of an agreeable odor has collected upon
the glass plate. This is collected and distilled, the portion passing
over at 219 F., being collected by itself.

Pure acetal is composed of C fi H l4 O 2 . It is a colorless liquid,
has a specific gravity of 0.821, and boils at 219.2 F. It has a
refreshing odor, calling to mind that of fruit ethers. By oxi-
dizing agents it is quickly converted into acetic acid. Nitrate of
silver in the presence of ammonia is, however, not reduced by it,
and it remains unchanged on boiling with potash lye. From its
composition acetal may be considered from several points of view.
It may be regarded as an ethyl alcohol (glycol) C 2 H 6 O 2 , in
which two atoms of hydrogen have been replaced by two mole-
cules of the radical ethyl C 2 H 5 , hence thus

f } - ^hyl-glycol

C 6 H 14 O 2 acetal.

This view of the composition of acetal is supported by the fact
that methyl or amyl can be substituted for either one or both mole-
cules of ethyl in the combination.

According to other opinions, acetal may be considered as a com-
bination of aldehyde and aldehyde ether :

C 2 H 4 O aldehyde

C 4 H 10 O aldehyde ether

C 6 H, 4 O 2 acetal,

or as a combination of aldehyde with ethyl alcohol, one molecule
of water in the latter having been replaced by the aldehyde :

Ethyl alcohol : 2(C.H 6 O) JI 2 O = C 4 H/)

aldehyde C 9 H,O
acetal C 6 H J4 O 2

By keeping in view the fact that the process of the formation
of vinegar is an oxidation of the alcohol which does not proceed
with equal energy in all parts of the apparatus, it will be under-
stood that during this process aldehyde, acetal, and acetic ether
can be formed which, if the operation be correctly conducted, will
be finally converted into acetic acid, though small quantities of
them will be found in the vinegar when just finished and exert
an influence upon its constitution.

42 VINEGAR, CIDER, AND FRUIT-WINES.

Acetic Acid.

Pure acetic acid, C 2 H 4 O 21 , cannot be directly obtained from
vinegar, but only from acetates by methods which will be described
later on. The strongest acetic acid which can be prepared is
known as glacial acetic acid, from its crystallizing in icy leaflets
at about 40 F. Above a temperature of about 60 F. the
crystals fuse to a thin, colorless liquid of an exceedingly pungent
and well r known odor. When diluted it has a pleasant acid taste
and agreeable odor. Pure acetic acid is a powerful restorative
when applied to the nostrils in impending fainting. It is the
strongest of the organic acids and nearly as acrimonious as sul-
phuric acid. When dropped on the skin it acts as an escharotic,
speedily raising a blister and producing much heat and rapid
inflammation ; when taken into the mouth or applied to any
mucous membrane it blackens like sulphuric acid. Highly con-
centrated acetic acid is a solvent of many volatile oils, resins,
albuminates, and glue; the ability to dissolve lemon oil is used in
the practice as a test for the high concentration of acetic acid,
since in the presence of only 2 per cent, of water in the acid
lemon oil is no longer dissolved by it.

The specific gravity of pure acetic acid is at 59 F. :

According to Onderaans 1.0553

Roscoe 1.0564

Kopp 1.0590

Mendelejeff 1.0607

Mohr 1.0600

According to Mohr's determinations, the specific gravity of
pure acetic acid varies much at different temperatures, it being

1.0630 at 54.5 F.

1.0600 " 59.0 "

1.0555 "i 68.0 "
1.0498 77.0 "

1.0480 79.0 "

Mixtures of acetic acid and water show a peculiar behavior in
regard to their specific gravity ; the latter rises steadily until the
content of water amounts to from 20 to 23 per cent. ; the density
of the liquid then diminishes so that a mixture containing 46

PRODUCTS OF ACETOUS FERMENTATION. 43

per cent, of water shows the same specific gravity as the anhy-
drous acid. From this point on, the specific gravities of the
mixtures decrease with the increase in the content of water.

This peculiar behavior of the mixtures renders the accurate
determination of the content of acid in a concentrated mixture
by means of the aerometer impossible. There are a number
of determinations of specific gravities of acetic acid with varying
contents of water (by Mohr, von der Toorn, Oudemans, etc.),
but they differ considerably from each other, like the tables at the
end of this volume, so that, while the specific gravity test answers
very well for the determination of the amount of anhydrous acid
in dilute solutions, it is very fallacious when the acid increases in
strength, and an accurate determination can only be effected by
chemical methods.

Highly concentrated acetic acid has recently found considerable
application in photography and surgery, and frequently occurs in
commerce in the form of so-called vinegar essence. The acetic
acid occurring under this name is generally prepared from wood
vinegar and is only fit for the preparation of table vinegar when
a chemical examination shows no trace of tar products, which are
formed in abundance, besides acetic acid, in the dry distillation of
wood.

In regard to the composition of acetic acid, it may be men-
tioned that one atom of hydrogen can be readily replaced by
univalent metals or univalent compound radicals which may be
expressed by

H lo

c 2 H 3 or

TT ~j

wherebv the acetic acid is considered 'as water tr > O in which

M J
one atom of hydrogen is replaced by the compound radical

C 2 H 3 O = acetyl

If the one atom of hydrogen standing by itself be replaced by
a univalent metal a neutral acetate is formed, for instance :

Na ) Q
C 2 H 3 OJ C
or sodium acetate.

If this atom of hydrogen is replaced by a uuivalent compound

44 VINEGAR, CIDER, AND FRUIT-WINES.

radical, for instance by methyl CH 3 or ethyl C 2 H 3 , the so-called

compound ethers are formed.

CH 3 \ n C 2 H 5 \

C 2 H 5 Oj C 2 H 3 0/ C

Acetic acid-methyl ether. Acetic acid ethyl ether.

If a bivalent metal or compound radical yields a neutral com-
bination with awtic acid, the substituted hydrogen in two mole-
cules of acetic acid must evidently be replaced by this bivalent
metal, for instance :

Ca \

2(C a H/>) j J *

Neutral calcium acetate.

Theoretical Yields of Acetic Acid.

In industries based upon chemical processes a distinction is
made between the theoretical and practical yields.

By theoretical yield is understood the quantity of the body
to be manufactured which would result if no losses of substance
were connected with the chemical process ; the practical yield,
on the other hand, is that in Avhich such losses are taken into
account, the average being ascertained by long-continued compari-
son of daily yields. The closer the practical yield approaches
the theoretical, the more suitable the method pursued in the fabri-
cation evidently is, and thus the manufacturer, who has a clear idea
of the theoretical yield, can readily judge of the value of his
method by comparing it with the practical yield attained.

Now suppose no loss of substance (by evaporation or forma-
tion of other combinations) occurs in the conversion of alcohol
into acetic acid, it can be readily calculated from the composition
of the two bodies how many parts by weight of acetic acid can
be formed from a determined number of parts by weight of
alcohol.

Alcohol has the composition C 2 H 8 O, or an atomic weight of 46,
because :

C 9 ...... 24

H n = 6

O = 16

Makes 46

PRODUCTS OF ACETOUS FERMENTATION. 45

The composition of acetic acid is C 2 H 4 O 2 aud its molecular
weight 60, because :

C 2 = 24

H<- 4

O 2 = 32

Makes . . 60

Hence from 46 parts by weight of alcohol 60 parts by weight
of acetic acid may be formed, or by reducing the ratio to 100
parts of alcohol it follows that 100 parts by weight of alcohol
must yield 130.43478 parts by weight of acetic acid. (The
increase in weight has to be attributed to the absorption of one
atom of oxygen, atomic weight 16, against the loss of two atoms
of hydrogen, atomic weight 2.) Since these two atoms of hydro-
gen are themselves oxidized to water by the absorption of oxygen,
the total yield from 100 parts by weight of alcohol would be :

Acetic acid 130.43478 parts by weight.

Water 39.13043 " " "

Total .... 169.56521 parts by weight.

The quantity of oxygen required to form acetic acid and water
from 46 parts by weight of alcohol, amounts to 32 parts by
weight, hence for 100 to 69.562 parts by weight. The oxygen
is conducted to the alcohol in the form of air, and it can be
readily calculated how much of the latter is required to convert
a given quantity of alcohol, for instance 100 grammes, into acetic
acid. In round numbers the air contains in 100 parts by weight
23 parts by weight of oxygen. Since 1 liter of air of 68 F.,
i. e., of that temperature which should at the least always prevail
in the vinegar generators, weighs 1.283 grammes, the oxygen con-
tained in it weighs 0.29509 grammes. Since, as above stated,
69.562 parts by weight are necessary for the conversion of 100
parts by weight of alcohol into acetic acid, it follows that 235.70
liters of air are required for the same purpose.

Examinations as to the content of oxygen in the 'air escaping
from weir-conducted vinegar generators have shown that on an
average only one-quarter of the entire content of oxygen is con-
sumed in the formation of vinegar; hence four times the theorcti-

46 VIXEGAR, CIDER, AND FRUIT- WIXES.

cally calculated quantity of air must pass through the apparatus
to completely convert the alcohol into acetic acid. Hence 100
grammes of alcohol require at least 942.92 liters of air for their
conversion into acetic acid, and, without being far wrong, it may
be assumed that in a vinegar factory, in round numbers, 1000
liters or one cubic metre of air are required for every 100 grammes
of alcohol to be converted into acetic acid.

A vinegar generator can, on an average, convert daily 3 liters
of alcohol into acetic acid ; 3 liters of absolute alcohol (specific
gravity 0.794) weigh 2382 grammes. Now, if, as stated above,
1 cubic metre of air is required for every 100 grammes of alcohol,
it follows that 23.82 cubic metres, or 23,820 liters of air must
pass daily through each vinegar generator in operation.*

Calculated to 16 working hours a day, somewhat more than 0.4
liters (more accurately 0.413 liters) must pass every second through
the generator in order to supply the quantity of oxygen required
for the conversion of alcohol into acetic acid.

Since the formation of vinegar has theoretically to be con-
sidered as a process of combustion, in which of 46 parts by
weight of alcohol 2 parts by weight of hydrogen, or of 100 parts
by weight of alcohol 4.34782 parts by weight of hydrogen, are
consumed, the quantity of heat liberated by the conversion of
100 parts by weight of alcohol into acetic acid can also be calcu-
lated. By combustion 1 gramme of hydrogen yields 34.126
units of heat, and hence 4.34782 grammes of hydrogen 148.373
units of heat, i. e., in the conversion of 100 grammes of alcohol
into acetic acid sufficient heat is liberated to heat 148.373 kilo-
grammes of water from C. to 1 0., or 1.48 kilogrammes from
C. to boiling, and thus a considerable development of heat is
caused by the rise of temperature in the apparatus in which a
vigorous formation of vinegar takes place.

In answer to the question, what can the practical manufacturer
of vinegar learn from these theoretical explanations, it may be
said there are many points of great importance for the execution
of the work. The calculation of air shows that the alcohol

* It is always supposed that the manufacture of vinegar is effected in
generators used in the quick process.

PRODUCTS OF ACETOUS FERMENTATION. 47

requi res a Jarge suppl y } but the generators in general use in the
quick process are by no means so arranged as to be adequate to
ie^ theoretical demands. In fact it may be said that most of
them allow~only a limited change of air and consequently work
slower than they actually could. That the generators now in use
are deficient is conclusively proved by the numerous constructions
which have_ been proposed, especially in modern times, whose
chief aim isjx) afford a free passage to the air.

The fact that considerable heat is developed in the interior of
the generator deserves consideration in connection with the heat-
ing of the manufactory. If the temperature of the latter is so
high as nearly to approach the optimum, i. e., the temperature
most favorable for the formation of vinegar, it may easily happen
that, in consequence of the vigorous oxidation of the alcohol, the
temperature in the interior of the generators is increased to such
an extent as to exceed this optimum, and the activity of the
vinegar ferment would immediately diminish and even cease
altogether.

If, on the other hand, the temperature of the workroom is
kept too low, the generators act sluggishly and do not produce as
much as when the correct conditions are observed. But as by
raising the temperature of the workroom the activity of the
generators is increased, too low a temperature is less injurious to
the regular course of the process than too high a one.

The optimum of the formation of vinegar is at about 86 F.,
and hence the aim should be to maintain this temperature as
nearly as possible in the interior of the generator. The temperature
of the workroom must, however, be kept sufficiently low, so that
the optimum in the interior of the generator cannot be exceeded.

Another factor may here be mentioned. The closer the tem-
perature in the interior of the generator approaches the optimum
mid the quicker the supply of air, the more alcohol and acetic
acid are lost by evaporation, or, in other words, the smaller the
yield ofacetic acid. By the skillful utilization of conditions the
manufacturer must aim to reduce this loss to a minimum, and
this can be best effected by a suitable arrangement of the work-
room. By regulating the change of air so that it is not greater
than absolutely necessary, the air will soon become so saturated

48 VINEGAR, CIDER, AND FRUIT-WINES.

with vapors of alcohol and acetic acid that no further loss will
take place until the renewing of the air in the workroom appears
necessary. In which manner the manufacturer is to work in
order to carry on the business most advantageously depends^ on
the conditions of trade. If large orders have to be filled, he will
endeavor to increase the capacity of the generators to the utmost
by maintaining the optimum of temperature and a vigorous
change of air in them, and in this case must submit to the in-
creased losses inseparably connected with this high performance.
If, on the other hand, he works for stock, he will not force the
capacity of the generators to the utmost, but in order to work as
cheaply as possible direct his attention to reduce the losses to a
minimum.

Yields of Acetic Acid obtained in the Practice.

By keeping for some time an accurate account of the actual
yields and comparing them with those theoretically obtainable,
the former will be found to fall more or less short of the latter,
and the difference will be the smaller the better the method of
fabrication in use.

In a vinegar factory occur many unavoidable losses, the
sources of which have been indicated iu the preceding explana-
tions ; alcohol and acetic acid evaporate, and besides a portion of
them is entirely destroyed by too much oxidation. Now a Joss
by evaporation, etc., of ten per cent, of the quantity of alcohol
originally used must no doubt be considered a large one, but from
numerous observations it may be asserted that even with the
greatest care in working the loss in vinegar factories is not less
than from 15 to 20 per cent., and may even be as much as 30
per cent.

These enormous losses of substance conclusively prove the de-
fectiveness of the processes in general use and the urgent neces-
sity for reformation. The experiments made for this purpose,
and which have been especially directed towards a remodelling of
the apparatus used, cannot be considered entirely satisfactory,
though they were partially instituted by practical manufacturers,
who, however, lacked the necessary theoretical education.

PRODUCTS OF ACETOUS FERMENTATION. 49

The principal requirement in our opinion is to provide the
generator with a suitable ventilator, which will allow of the pas-
sage through the generator of exactly the quantity of air required
foTtEe conversion of the alcohol into acetic acid, and is so con-
structed that the vapors of alcohol and acetic acid (or at least the
larger portion) carried away by the current of air are condensed
and thus regained.

A vinegar generator has frequently been compared to a furnace,
and in continuation of this comparison it may be said, that the
construction generally used is a furnace lacking every arrange-
ment for the regulation of combustion. In such a furnace as
much fuel is burned as corresponds to the quantity of oxygen
entering, while in a furnace of suitable construction the combus-
tion of fuel can be accurately regulated by increasing or de-
creasing at will the supply of air by means of a simple con-
trivance.

A vinegar generator of suitable construction should be provided
with a similar arrangement. If the thermometer on the apparatus
shows too low a temperature hence too slow a process of oxida-
tion the course of the operation can in a short time be accel-
erated by the production of a stronger current of air and the
temperature correspondingly increased. If, on the other hand,
oxidation proceeds too rapidly, which on account of the high
temperature then prevailing in the apparatus is accompanied by
considerable loss of substance, it can be quickly reduced to
within the correct limits by decreasing the current of air. An
apparatus unprovided with a ventilator is left more or less to
itself, while one provided with such an arrangement is under the
entire control of the manufacturer.

50 VINEGAR. CIDER, AND FRUIT-WINES.

CHAPTER V.

METHODS OF FABRICATION OF VINEGAR.

THE fabrication of vinegar from wine is undoubtedly the
oldest and most simple method known, since it is only necessary
to leave the wine to itself at a sufficiently high temperature to
find it within a certain time converted into vinegar. A similar
process takes place in all fermented fruit juices resembling wine.

It would, therefore, seem proper to commence the description
of the various methods of fabrication of vinegar with this simple
process, but for reasons of an entirely practical nature it has
been concluded not to do so.

Since alcoholic fluids directly formed by the vinous fermenta-
tion of sacchariferous plant juices possess the property of chang-
ing under circumstances favorable to acetous fermentation into
vinegar, it is evident that the latter can be prepared from them,
and, in fact, it is possible to prepare it from all sweet fruits and
parts of plants, such as cherries, strawberries, figs, bananas, etc.,
as well as from the juice of the sugar-cane, beet, chicory root, etc.

Honey, which represents a concentrated solution of ferment-
able sugar, as well as crystallized cane sugar, can likewise be in-
directly used for the preparation of vinegar, since solutions of
either can be brought into vinous fermentation and the resulting
alcohol converted into acetic acid.

By malting grain a peculiar body called diastase is formed,
which possesses the property of converting starch into ferment-
able sugar, and upon this fact is based the manufacture of beer
and alcohol. In an indirect manner (the starch having to be
converted first into sugar, and the latter into alcohol) it is, there-
fore, possible to prepare vinegar from every substance containing
starch, and for this reason we can speak of grain and malt
vinegars. The beer prepared from the malt containing already

METHODS OF FABRICATION OF VINEGAR. 51

a certain quantity of alcohol can thus be directly converted into
vinegar.

Alcohol furnishing ultimately the material for the fabrication
of vinegar, the direct use of dilute alcohol or spirit of wine for the
manufacture of vinegar became obvious. By the employment of
a suitable process, i. e., one corresponding to the 1 laws of acetous
fermentation, it was found that the conversion of dilute alcohol
into acetic acid could be effected in a much shorter time than by
the old method, and upon this process is based the quick method
of fabrication now in general use. A distinction may, therefore,
be made between two principal methods of fabrication, viz., the
older or slow process, which requires more time, and the more
modern or quick process.

In the old process many modifications are found, which are
partially based upon old usage and partially upon the difference
in the chemical composition of the raw material used. Beer, for
instance, which contains only about 4 per cent, of alcohol and
a large quantity of extractive substances (sugar, dextrin, salts,
etc.), requires a different treatment from wine, which contains on
an average 10 per cent, of alcohol, but scarcely 2 per cent, of
extractive substances. Fruit-wines (cider, etc.), with only 5 to ft
per cent, of alcohol but a large quantity of extractive substances,
again require different treatment from grape wine, etc., so that,
in a certain sense, it may be said there are as many different
methods of fabricating vinegar as there are fundamental materials,
and by taking into consideration the difference in the chemical
composition of the latter, it is evident that there must be just as
many varieties of vinegar. Besides acetic acid and a certain
amount of water, every vinegar contains other substances, which,
though frequently only present in very minute quantities, never-
theless exert considerable influence upon its properties.

Even vinegar obtained from dilute alcohol shows differences in
odor, which depend on the material used in the preparation of
the specific alcohol. Potato alcohol always contains traces of
potato fusel oil (amyl alcohol), while certain fusel oils are found
in alcohol prepared from grain or molasses. In the oxidation of
the alcohol by the vinegar ferment these fusel oils are also oxi-

52 VINEGAR, CIDER, AND FRUIT-WINES.

dized and converted into combinations distinguished by their
peculiar and very strong odor.

Though these bodies occur in the vinegar in such minute quan-
tities that they can scarcely be determined by chemical analysis,
an expert can detect them by the sense of smell, and from the
specific odor of the vinegar form a conclusive judgment as to the
material used in its preparation.

The differences in vinegar from wine, fruit, beer, and malt are
still more prominent, and extend not only to the odor but also to
the taste. Besides a specific odoriferous principle every wine
contains oenanthic ether, tartar, tartaric and succinic acids, gly-
cerin, and a series of extractive substances not thoroughly known.
The odoriferous substances and the oenanthic ether also undergo
alteration in the oxidation of alcohol, and are converted into
other odoriferous combinations, with such a characteristic odor
that wine vinegar can at once be recognized as such by it. On
account of the presence of so many substances possessing a
specific taste, that of the wine vinegar must, of course, differ
from that of pure dilute acetic acid.

Similar conditions prevail in fruit-wine, beer, malt-extract, etc.,
and hence vinegar prepared from these fluids must possess definite
properties.

CHAPTER VI.

QUICK PROCESS OF FABRICATION OF VINEGAR.

^\

IN 1823 Schutzenbach conceived the idea that by greatly en-
larging the relative surfaces of contact of the alcoholic solution
and air containing oxygen, the process of acetification would be
greatly facilitated. His experiments proved successful, and soon
after the quick vinegar process was generally adopted. Analo-
gous processes were nearly at the same time invented, in Germany
by Wagmann, and in England by Ham.

The principle involved of course depends on an extreme
division of the liquid being effected. This is very skilfully con-

QUICK PROCESS OF FABRICATION OF VINEGAR. 53

trivcd. By making the alcoholic solution percolate slowly
through and diffuse over a mass of shavings, wooden blocks,
pieces of coal or cork, etc., it forms a very thin layer, the surface
of which is very extensive, and is therefore better adapted for
the chemical appropriation of the oxygen in the current of air
which is transmitted over it. The mass of shavings, etc., serves
not only for the division of the liquid into fine drops but also as
a carrier of the vinegar ferment.

It will be readily understood that this arrangement presents in
a high degree all the conditions required for the formation of
vinegar : the vinegar ferment upon the shavings acquires from
the liquid all the substances required for its maintenance and
augmentation, and by the current of air passing through between
the shavings is enabled to oxidize the alcohol to acetic acid. This
process taking place simultaneously on thousands of points in a
normally working generator explains why a large quantity of
alcohol can in a comparatively short time be converted into
acetic acid. The term quick process is hence very appropriate -
for this method, it differing from the older slow process only in
less time being required for its execution ; the chemical processes
are the same in both cases.

It will be seen that the generator, technically called " gradu-
ator," used in the quick process may be compared to a furnace in
which the fuel (in this case the alcoholic fluid) is introduced from
above and the air from below. The spaces between the shavings,
etc., may be compared to the interstices of a grate ; combustion
takes place on the points of contact of the alcoholic fluid, vinegar
ferment, and air. The product of (partial) combustion the
vinegar collects in a reservoir in the lower part of the
generator.

Eachj^enerator, as previously stated, requires about 0.4 liter of
air per second, which must ascend uniformly from below through
tKeTnass of shavings, etc. At the first glance this would seem
very simple, but its practical execution is accompanied by many
difficulties, and hence a large number of various constructions of
generators have been proposed by which this object is claimed to
lie best attained.

54 VINEGAR, CIDER, AND FRUIT-WINES.

Arrangement of the Generators.

A generator consists of a large vessel divided into three spaces
above one another, the uppermost serving for the division of the
alcoholic liquid into many small drops ; in the centre one, which
forms the largest part of the apparatus, the alcoholic liquid is
converted into vinegar, while the lower one serves for the collec-
tion of the vinegar.

The best form of t