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Full text of "A practical treatise on the manufacture of vinegar, with special consideration of wood vinegar and other by-products obtained in the destructive distillation of wood; the preparation of acetates. Manufacture of cider and fruit-wines; preservation of fruits and vegetables by canning and evaporation; preparation of fruit-butters, jellies, marmalades, pickles, mustards, etc. Preservation of meat, fish and eggs"

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111-117 E. Chestnut Street, 



MANUFACTURE OF VINEGAR has been out of print for sometime, 
and there being no recent work to take its place notwithstand- 
ing the constant demand for a book on the various important 
branches of industry treated of, the publication of a new edition 
was deemed advisable. 

Like the previous editions the volume is divided into three 

Part I. is devoted to the Manufacture of Vinegar, and in- 
cludes the production of wood vinegar and other by-products 
obtained in the destructive distillation of wood, as well as the 
preparation of acetates. 

Part II. contains the Manufacture of Cider, Fruit Wines, 
etc., and Part III. the Preservation by various methods of 
Fruit and Vegetables, and of Meat, Fish and Eggs. 

In this, the third edition, no essential changes have been 
made in the arrangement of the book, bait it has been thor- 
oughly revised and largely re-written, old and obsolete matter 
having been eliminated and new material introduced. The 
best authorities have been diligently consulted and freely 
drawn on, for which due credit has, whenever possible, been 
given in the text. 

It is hoped that this new edition will meet with the same 
favorable reception as the previous ones, and that it will be of 
practical utility. 

A copious table of contents as well as a very full index will 
render reference to any subject in the book prompt and easy. 

PHILADELPHIA, November 16, 1914. 

W. T. B. 








Nature of vinegar; Early knowledge of vinegar; Use of vinegar as a medicine 
by Hippocrates; Anecdote of Cleopatra; Use of vinegar by Hannibal for 
dissolving rocks. ........... 1 

The process of increasing the strength of vinegar by distillation described by 
Gerber in the eighth century; Other early historical data about vinegar; 
Stael's method of strengthening vinegar; Count de Laragnais and Marquis 
de Courtenvaux' experiments. . ....... 2 

Loewitz's method of strengthening vinegar; Glacial acetic acid; Historical 
data regarding the formation of an acetic body in the destructive distilla- 
tion of wood; Determination of the exact chemical constitution of acetic 
acid by Berzelius, and that of alcohol by Saussure; Historical data relating 
to the generation of acetic acid; Introduction of the quick process of manu- 
facturing vinegar, in 1823, by Schiitzenbach; Method of making vinegar 
from wine made known by Boerhave, in 1732 ...... 3 

Schiitzenbach' s original plan of working still in use in some localities; Neces- 
sity of progress in making vinegar by the' quick process; Great purity of 
acetic acid as at present prepared from wood; " Vinegar essence" and its 
uses ..... .......... 4 

Difference between the pure acetic acid produced from wood and vinegar pre- 
pared from various materials; Principal defects in the process of making 
vinegar by the quick process in general use 5 

Probability of the discovery of a process for the production of acetic acid 
from its elements ......... 6 



Chemical processes by which acetic acid in large quantities is formed . . 7 
Liebig's theory of the formation of vinegar; Present view of the formation of 
vinegar; Pasteur's theory; Difference between Pasteur's and Nageli's views; 
Nomenclature of organisms producing fermentation; The vinegar or acetic 
ferment ............. 8 




Occurrence of acetic acid in nature; Formation of acetic acid by chemical 
processes; Formation of acetic acid by the action of very finely divided 
platinum upon alcohol .... . . . . . 9 

Development of mother of vinegar; Pasteups investigations regarding the 
relation of mother of vinegar to the formation of vinegar; Botanical na- 
ture of the organisms causing the formation of vinegar ... .11 

Disease causing bacteria; Hansen's investigations of the species of bacteria . 12 


The vinegar ferment, its origin and its distribution; Fluid especially adapted 
for nutriment; Experiment showing the conversion of wine into vinegar 
by the vinegar ferment .13 

Difference between the living and dead ferment as seen under the micro- 
scope; Requirements of the ferment for its propagation . . . .15 

Results of the withdrawal of oxygen from the ferment; Experiment showing 
the great rapidity of propagation of the vinegar ferment; Conditions for 
the nutriment of the ferment; Factors required for the settlement of the 
vinegar bacteria upon a fluid and for their vigorous propagation . . 1& 

Composition of the nutrient fluid; A large content of alcohol in the nutrient 
fluid detrimental to the vegetation of the vinegar ferment; Experiment 
showing that the ferment cannot live in dilute alcohol alone . . .17 

Preparation of a fluid containing all the substances essential to the nutriment 
of the ferment; Sensitiveness of the ferment to sudden changes in the com- 
position of the fluid upon which it lives; The process of nutriment of the 
vinegar ferment. . . . . . . . . . . .18 

Supply of air required for the ferment; Limits of temperature at which the 
propagation of the ferment and its vinegar-forming activities are greatest; 
Effect of low temperature upon the ferment. . . . . .19 

Reason why acetic degeneration is not known in cold wine cellars; Reasons 
for the frequent occurrence of disturbances in the formation of vinegar at 
a high temperature. . ......... 20 

Mother of vinegar; Origin of the term; Different opinions regarding the na- 
ture of mother of vinegar; Formation of mother of vinegar. . . . 21 

Summary of the theoretical conditions of frhe formation of vinegar. . . 22 



The regular propagation of the ferment the main point of the entire manu- 
facture; Loss of alcohol in the production. ...... 23 

Substances, besides alcohol and carbonic acid, formed in vinous fermentation. 
Characteristic properties imparted to alcohol by fusel oils; Aromatic sub- 
stances which reach the vinegar through the conversion of fusel oils; 
Acetic aldehyde or acetaldehyde, commonly called aldehyde. . .24 

Preparation of pure aldehyde; Acetal and its preparation. . . 25 



Composition and nature of pure acetal 26 

Acetic acid and its properties. ......... 27 

Peculiar behavior of mixtures of acetic acid and water in regard to their spe- 
cific gravity; Vinegar essence and its use for the preparation of table vin- 
egar; Composition of acetic acid. ........ 

Theoretical yield of acetic acid. . . . . . . . 29 

Manner of calculating the theoretical yield of acetic acid from alcohol. . 30 
Quantity of oxygen required to form acetic acid and water from alcohol; 
Quantity of alcohol which can daily be converted into vinegar by a gene- 
rator ( 31 

Calculation of the quantity of heat liberated by the conversion of alcohol in- 
to acetic acid; What the manufacturer can learn from theoretical expla- 
nations . 32 

The acme of temperature and what is meant by it; Loss of alcohol and acetic 
acid by evaporation and its reduction. ....... 33- 

Conditions on which the most advantageous working depends; Yields of acetic 
acid obtained in practice . . . . . . . . . . 34 

Comparison of a vinegar generator to a furnace . . . . . .35 


Designation of the various methods employed; Substances which may be used 

for the preparation of vinegar ......... 36 

Alcohol the ultimate material for the manufacture of vinegar; The old or 

slow process and modifications of it 37 

Difference in the properties of vinegar derived from various sources . . 38 


Invention of Schiitzenbach and analogous processes; On what the principle 

involved depends; Comparison of the generator or graduator to a furnace . 39 
Generators; Best form of the generator. ....... 40 

Kinds of wood suitable for of generators . . . .41 

Variations in the dimensions of the generators ...... 42 

Dimensions of the most suitable generator; Cover of the generator . . 43 
Disadvantage of a number of obliquely bored holes below the false bottom; 

Scheme of incorrect conduction of air in generators ..... 44 
Contrivances for the discharge of vinegar collected in the lower portion of 

the generator ............ 45 

Arrangement of the perforated false head of the generator . . . . 46 

Arrangement for regulating the inflow of air from below . . . .47 

Modification of the false head . . . . . . .48 

The tilting trough 49 

The sparger ............. 50 

Principal requisite for the correct working of the sparger . . . .51 



A thermometer an indispensable adjunct to a generator; Filling the gener- 
ators, and materials used for this purpose. ...... 52 

General use of beech shavings, their advantages and preparation; Volume 
represented by a shaving in a rolled state; Space required for such shaving. 53 

Freeing the shavings from extractive substances by water and by steaming; 
Drying the steamed shavings 54 

Swelling the shavings and placing them in the generator; Advantage of hav- 
ing all the generators of the same size. ....... 55 


Principal requisites to be observed in a suitable arrangement; Provisions for 
the maintenance of a uniform temperature .58 

Materials for the floor; Heating of the workroom, and apparatus for this pur- 
pose .............. 57 

Advantage of the use of maximum and minimum thermometers . . .59 

Location of the reservoirs in factories arranged according to the automatic 
system 60 



English process of sucking a current of air from above to below through 

every generator; Incorrectness of this method 61 

Principal reason advanced for the use of a current of air from above to 

below - 62 

Schulze's ventilating apparatus and generator ...... 63 

Generators with constant ventilation and condensation; An apparatus well 

adapted for the purpose .......... 65 

Proposed method of regaining the vapors; Objection to this method . . 68 

4Singer* s general >r 69 

Michaelis' revolving generator ......... 72 


Principal work which has to be performed in a vinegar factory; Disadvan- 
tages of pouring at stated intervals the alcoholic fluid into the generators. 73 

Debilitation of the vinegar ferment in consequence of repeated reduction of 
the temperature in the generators; Explanation of many apparently inex- 
plicable disturbances ......... 74 

Advantages to be derived from the use of simple automatic contrivances; 
Continuously-acting apparatus; The terrace system . . . . .75 

Arrangement of a factory according to the terrace system; Drawback of this 
system ........... 77 



Mode of working according to the terrace system 78 

Lenze's chamber generator, and the principles upon which its construction is 

based 80 

Mode of operating Lenze's chamber generator; Plate generator, patented by 

Dr. Bersch 82 

Periodically working apparatus; The three-group system; Mechanical appli- 
ances for admitting at certain intervals a fixed quantity of alcoholic fluid 
into the generators; Modification of the tilting trough . . . .86 

The siphon barrel 88 

The bell-siphon ; Example for calculating the space required beneath the 

false bottom for the reception of the vinegar 89 

Arrangement of a vinegar factory working according to the automatic prin- 
ciple; Arrangement of the generators in groups. . . . . .90 

Description of a periodically-working establishment with 24 generators. . 91 
Manner of working in such an establishment. ...... 93 

Apparatus for heating the alcoholic liquid ....... 95 



Acetification of the generators; Quantities of vinegar required for complete 
acetitication . . . . . . . . . . . .96 

Example illustrating the gradual commencement of regular production; Ac- 
celerated acetification .......... 97 

How the removal of water from the shavings and its substitution by vinegar 
are effected ............ 98 

Use of artificially dried shavings; Induction of the operation with an artifi- 
cial culture of vinegar ferment. ....... .99 

Pure culture of vinegar ferment and best fluid for the purpose. . . . 100 

Preparation of nourishing fluid; Manner of cultivating vinegar ferment. . 101 

Abortive culture of vinegar ferment 102 

Disturbances by suddenly changing the nutrient fluid of the ferment, and 
their prevention. ........... 103 


Definition of the term 'alcoholic liquid;" Reason why a content of vinegar 
in the alcoholic liquid exerts a favorable effect upon the formation of vin- 
egar. 104 

Proof that the alcoholic liquid does not require any considerable quantity of 
acetic acid for its conversion into vinegar. . ..... 105 

Reason why it is preferable to gradually increase the content of alcohol in 
the alcoholic liquid; Experiment showing the destruction of acetic acid by 
the vinegar ferment in the absence of alcohol 106 



Limit of acetic acid vinegar should have ; Conditions on which the advanta- 
geous manufacture of high-graded or weak vinegar depends ; Quantity of 
beer to be added to the alcoholic liquid .107 

Quantity of finished vinegar to be added to the alcoholic liquid; Table of 
the theoretical yield of acetic acid from alcohol . . . .308 

lleason why practically less vinegar with a smaller percentage of acetic an- 
hydride is obtained ; Table showing the content of alcohol required in an 
alcoholic liquid for the production of vinegar with a certain content of 
acetic acid ; Calculation for finding the number of gallons of water which 
have to be added to alcohol of known strength to obtain an alcoholic liquid 
with the desired- percentage of alcohol 109 

Examples of the composition of alcoholic liquid . . . . . .110 

Use of low wine for the preparation of alcoholic liquid . . . . .111 

Determination of the content of alcohol in spirits of wine ; Compilation show- 
ing the manner of preparing alcoholic liquid according to rational princi- 
ples , 112 

Determination of acetic acid in vinegar; Constitution of the fundamental 
materials used in the preparation of alcoholic liquid . .... 113 

Water suitable and unsuitable for the preparation of vinegar; Behavior of 
mixtures of water and alcohol . . . . . . . . .114 

River water and the possible introduction of vinegar eels by it; Importance 
of the constitution of the spirits of wine used 115 

Advisability of using a mixture of rectified and crude potato alcohol . . 116 


Simplicity of the work; Reduction of alcohol with water . . . .117 

Quantity of fluid to be worked in a generator in the course of a day; Gradual 
strengthening of the alcoholic liquid with alcohol ..... 118 

Temperature to be maintained in the interior of the generators; Determina- 
tion of acetic acid and of alcohol in the fluid running off from the gener- 
ators 119 

Plan of operation as resolved from the results of tests ..... 120 

The actual prodoction according to the old method; Production of so-called 
triple vinegar ............ 121 

Group system; Principle of the operation; Operation with three groups of 
generators. . . . . . . . . . . . .122 

Taking samples for determining the content of acetic acid and alcohol; Cross- 
ing the generators . . . . . . . . . . .124 

Group system with automatic contrivances; Preparation of the alcoholic 
liquid for 12 per cent, vinegar . . . . . . . . .125 

Regulation of the automatic contrivances; Operation with the automatic 

system . 126 

Recognition of a disturbance in any one of the generators, and its preven- 
tion . .127 




How serious disturbances can be avoided; Irregularities due to the nourish- 
ing substances of the ferment, and how to remedy them .... 128 

Sweet beer wort or malt extract for strengthening weak-working generators; 
Favorable effect of phosphates; Disturbances ascribable to the quantity of 
newly-formed acetic acid . . . . . . . . . .129 

Controlling the working of the generators by frequent determinations of the 
acetic acid; Phenomena indicative of the generator not being able to mas- 
ter the alcoholic liquid introduced; Restoration of the generator to a proper 
state of working ........... 130 

Cause of the heating of generators; Sliming of the shavings in generators . 131 
Causes of sliming; Alteration which takes place in the shavings . . . 132 
Constitution of the slimy coat; How sliming can be remedied at the com- 
mencement of the evil . . . . . . . . . . 133 

Disturbances due to vinegar eels ......... 135 

Remedies for the suppression of vinegar eels. ...... 137 

Sulphuring the generator and apparatus for that purpose .... 138 

Disturbances due to vinegar lice (vinegar mites) . . . ... . 140 

Vinegar flies 142 


Utensils required, Induction of the formation of vinegar; The wash and its 
preparation ............ 143 

Indications of the commencement of acetification; Excitation of " lazy " 
barrels 144 

Time required for acetification; Barreling and storing the vinegar; Modifi- 
cations of the slow process. ......... 145 

Household manufacture of vinegar . . . . . . . .147 

Preparation of vinegar with the assistance of platinum black . . .. 148 


Odor of freshly-prepared vinegar, and on what it depends; Filling the 
barrels 149 

Means of improving the odor of vinegar ..'..... 150 

Drawing oft' the vinegar from the sediment in the barrel; Constituents of the 
vinegar brought into storage barrels ........ 151 

Storing of vinegar; Processes which take place during storing. . . . 152 
Filtering vinegar before bringing it into the storage barrels; Heating the 
vinegar, and apparatus used. ......... 153 

Filtration of vinegar and filters for this purpose 155 



Sulphuring of vinegar. . 158 

Fining vinegar; Coloring vinegar. ........ 159 



Formation of diastase; How vinegar may be made from starch. . . . 160 

Beer-wort not a suitable material for vinegar. . . . . . .161 

Fermented whiskey mashes for the manufacture of vinegar; Manufacture of 

malt or grain vinegar. 162 

Most suitable variety of malt for making vinegar 163 

Theoretical part in mashing; After-effect of the diastase 164 

"Doughingin" 165 

On what the strength of the vinegar to be made depends; Setting the mash 
with yeast; Preparation of compressed yeast; Treatment of the completely 
fermented "ripe" mash; Heating the mash. ...... 166 

Conversion of the fermented malt-wort into vinegar. . . . . .167 

Filtration of malt vinegar in rffininy or rape vessels; Manufacture of malt 

vinegar by "fielding" ; Utilization of sour ale and beer for vinegar. . . 168 
Vinegar from sugar beets, and from sugar, fruits and berries. . . . 169 

Making vinegar on a small scale for domestic use. . . . . .170 

Table showing the average content of sugar and free acid in the most com- 
mon varieties of fruits; Treatment of currant juice for making vinegar. . 171 
Preparation of vinegar from other berries. ....... 172 

Peaches as vinegar stock; Cider vinegar. ....... 173 

Use of a generator for the conversion of cider into vinegar; Directions for 
home-made cider vinegar, by Mr. Walter G. Sackett 174 



Groups of specialties; Perfumed vinegar; Aromatized vinegar . . . 178 

Manner of dissolving volatile oils in vinegar ...... 179 

Preparation of aromatized vinegar; Toilet vinegars; Mohr's volatile spirits of 
vinegar; Aromatic vinegar ......... 180 

Henry's vinegar; Vinaigre des quatre voleurs; Hygienic or preventive vine- 
gar; Cosmetic vinegar; Table vinegars; Anise vinegar . . . .181 

Anchovy vinegar; Tarragon vinegar; Compound tarragon vinegar; Effervesc- 
ing vinegar 182 

Herb vinegar; Pineapple vinegar; Celery vinegar; Clove vinegar; Lovage 
vinegar; Raspberry vinegar 183 

Preparation of acetic ether. 184 


Materials for wine-vinegar; Theoretical and actual yield .... 186 
Reasons why wine-vinegar is superior to the ordinary products . , ; . 187 



Table showing the composition of wine and of the vinegar formed from it; 

"Sick" wines 188 

Lactic acid and acetic degenerations of wine ...... 189 

Young wine attacked by acid degeneration for making vinegar; Preparation 
of after-wine, according to Petiot . . . . . . . .190 

Use of this wine for making vinegar ........ 192 

Older method of making wine vinegar; Orleans or old French process of 

making wine-vinegar .193 

Pasteur's or modern French method of preparing wine-vinegar . . . 196 
Pasteurization and apparatus used; Undesirable phenomena which may ap- 
pear in the conversion of wine into vinegar ...... 198 

Claudon's method of making wine-vinegar described by Frederic T. Bioletti. 200 
Bersch's method of making wine-vinegar; Culture of pure vinegar ferment . 201 
Variety of wine most suitable for making vinegar . . . . . 203 

Apparatus for making wine vinegar ........ 204 

Operation in a wine-vinegar factory ........ 205 

Disturbances in the production of wine-vinegar; Filtering wine-vinegar . 208 
Storing and bottling wine-vinegar; Pasteurizing bottled vinegar and appa- 
ratus for that purpose ..'.... ..... 209 

Wine-vinegar by the quick process . . . . . . . .210 

Wine-vinegar from marc . . . . . . . . . .211 



Determination of sugar .......... 213 

Determination of alcohol; The alcoholometer 214 

Determination of the alcohol by the distilling test, and apparatus used. . 215 

Determination of the alcohol by the ebullioscope 217 

Vidal-Malligaud's ebullioscope ......... 218 

Determination of the content of acetic anhydride in vinegar, or acetometry: 

Titration or volumetric analysis, and apparatus for that purpose . . 220 
Calculation of the quantity of acetic acid in the vinegar examined; Determi- 
nation of the strength of vinegar by the vinegar tester, described by Fred- 
.eric T. Bioletti . 224 



Detection of acids; Sulphuric acid 227 

Hydrochloric acid; Nitric acid; Lactic acid; Sulphurous acid . . . 228 

Detection of metals; Iron; Copper; Tin 229 

Determination of the derivation of a vinegar ...... 230- 





Constitution of wood; Specific gravity of different woods .... 233 
Average composition of air-dry wood; Decomposition of wood . . . 234 
Effect of heating on wood; Effect of acids on wood ..... 235 

Effect of dilute aqueous solutions of alkalies on cellulose 236 

Products of destructive distillation; Gaseous products of distillation . . 237 
Table showing the order in which the gaseous combinations are formed at 
different temperatures; Composition of wood gases. .... 238 

Origin of many bodies which appear among the products of the decomposi- 
tion of wood. . . . . ....... 239 

Quantity of gas yielded by wood by destructive distillation. . . . 241 

Liquid products of distillation; Wood vinegar; Fatty acids in wood vinegar 242 
Production of methyl alcohol from marsh gas; Formation of acetone. . 243 

Variation in the quantities of the bodies of which wood-vinegar is composed; 

Tar . i>44 

Composition of the larger quantity of the tar products; Combinations which 
are definitely known. . . . . . . . ... 245 

"Yield of tar obtained in the destructive distillation of wood; Table of bodies 
of technical importance appearing in the destructive distillation of wood. 246 

'Character of wood tar ; Retort tar ; Boiled tar - . . 247 

Properties of the combinations formed in wood tar; Acetic acid; Acetone. . 248 
Methyl acetate; Aldehyde or acetaldehyde; Methyl alcohol or wood spirit 249 
Tar products hydrocarbons of the series C n H 2n -6 250 

Naphthalene and paraffin. . . . . . . . . . 251 

Tar products containing oxygen (creosote); Properties of wood-tar creosote 252 
Illuminating gases from wood; Complete series of compounds occurring in wood 
tar mentioned by various chemists. ........ 253 


Selection of the apparatus for the installation of a plant for the utilization of 

wood in a thermo-chemical way. ........ 254 

Processes by which acetic acid on a large scale can be prepared. . . 255 

Kilns or ovens and retorts; Charring of wood in heaps or pits. . . . 256 

Schwartz's oven . . . ...... 257 

Reichenbach's oven . . . . . . . . . . . 259 

Swedish oven 260 

Carbo-oven ; Retorts 262 

Horizontal retorts; Wrought-iron retort of suitable construction . . . 263 

Manner of bricking in six retorts 2(54 

Utilization of the gases escaping from the condenser for heating . . . 266 

-Oven-retort largely used in this country; Coolers; Vertical retorts . . 267 

-Arrangement of the retort-ovens and the lifting apparatus .... 268 



Distilling apparatus for wood waste; Halliday's apparatus .... 271 
Apparatus suitable for the distillation of sawdust and waste of wood in gen- 
eral 273 

On what the selection of apparatus for the destructive distillation of wood 

depends 274 

Coolers; Counter-current pipe cooler ........ 275 

Most suitable way of connecting two pipes ....... 276 

Prevention of obstruction in the pipes. ....... 277 

Box cooler; Collection of gas ......... 278 

Reservoirs for the product of distillation 279 

Collecting boxes 281 

Utilization of the gases . . . . . . . . . 282 


Operation with a larger number of retorts; On what the time during which 
distillation has to be continued depends ....... 284 

Mode of placing a thermometer in one of the retorts ..... 2K5 

Use of antimony in determining the commencement of the end of distillation. 286 
Size of vats for the reception of the distillate; Collecting boxes sunk in the 

ground 287 

Yield of products; Manner in which accurate data regarding the quantities 
of wood-vinegar and tar from a variety of wood may be obtained; Stolze's 
experiments ............ 288 

Results obtained by Assmus in manufacturing on a large scale; Yields ob- 
tained with retorts, according to Klar 289 


Uses of crude wood-vinegar; Separation of acetic acid. .... 290 

Separation of the wood-vinegar fr m the tar; Methods by which concentrated 
acetic acid can be obtained from crude wood-vinegar. . . . . 291 

Distilled wood-vinegar .......... 292 

F. H. Meyer's system of distilling the crude wood-vinegar in multiple evap- 
orators in vacuum; Properties of freshly-distilled wood-vinegar. . . 293 
Various methods proposed for the purification of wood-vinegar . . . 294 
Production of pure acetic i cid from wood-vinegar; Preparation of calcium 
acetate ............. 296 

Evaporating pans ........... 297 

Klar's continuously. working apparatus for evaporating and drying the cal- 
cium acetate ............ 298 

Preparation of sodium acetate ......... 299 

Filter for obtaining pure sodium acetate ....... 301 

Mode of obtaining sodium acetate for the preparation of perfectly pure acetic 
acid . 302 



Preparation of sodium acetate from calcium acetate 304 

Preparation of acetic acid from the acetates; Processes used; Hydrochloric 
acid process ............ 305 

Sulphuric acid process. .......... 307 

Plant arranged for the sulphuric acid process 308 

Preparation of glacial acetic acid. ........ 309 

Vacuum process for obtaining highly concentrated acetic acid . . .310 
Preparation of glacial acetic acid of the highest concentration . . .311 


Properties of acetates . ........... 313 

Potassium acetate ........... 314 

Potassium acid acetate or potassium diacetate; Sodium acetate; Ammonium 
acetate, neutral acetate of ammonia . . . . . . .316 

Calcium acetate; Barium acetate. . . . . . . . . 317 

Magnesium acetate ........... 319 

Aluminium acetate; Normal or f aluminium acetate; Basic aluminium ace- 
tate; Basic aluminium g acetate ........ 320 

Maganese acetate 323 

Iron acetate; Ferrous acetate, black mordant 324 

Neutral ferric acetate, sesquiacetate of iron. ...... 326 

Chromium acetate; Chromous acetate; Nickel acetate; Cobalt acetate . . 328 
Zinc acetate; Copper acetates; Cuprous acetate; Neutral cupric acetate, crys- 
tallized verdigris 329 

Basic cupric acetates; Sesquibasic cupric acetate ...... 332 

Tribasic cupric acetate; French and English verdigris. .... 333 

Lead acetates; Neutral acetate of lead (sugar of lead); Volkel's method . 335 
Stein's method, and distilling apparatus used ...... 337 

Crystallizing pans ........... 338 

Preparation of sugar of lead from metallic lead, according to Berard . . 340 
Brown acetate of lead . .......... 341 

Properties of acetate of lead 342 

Basic lead acetates; Manufacture of white lead according to the French 
method; Lead vinegar or extract of lead.. ...... 344 

Lead sesquibasic acetate, triplumbic tetracetate ...... 345 

Sexbasic acetate of lead; Uranium acetate; Tin acetate; Bismuth acetate; Mer- 
curous acetate. ........... 346 

Mercuric acetate; Silver acetate 347 




Preparation of wood spirit; Constitution of the crude wood spirit of com- 
merce; Wood spirit for denaturing purposes ...... 348 



Constitution of pure wood spirit; Rectification of crude wood spirit solutions, 

and still for the purpose .......... 3-19 

Preparation of wood spirit suitable for denaturing purposes .... 351 

Preparation of acetone; Properties of acetone; Decomposition of the calcium 

acetate, and apparatus for this purpose 352 

Rectification of the crude distillate; Arrangement of a plant for the produc- 
tion of acetone. ........... 353 

Manufacture of pure acetone according to F. H. Meyer's system; Working 

the wood tar; Preparation of creosote and tar oils; Distillation of wood tar 355 

Yield from tar of hard woods by distillat on ...... 350 

Rectification of the oils; Manner of obtaining creosote from the distillate . 357 

Working the heavy oils; Results of experiments regarding birch-tar oil . 358 




Definition of the term wine; Ingred ents which are added to artificial wines; 
Ripening of fruits ........... 360 

Occurrence and behavior of pectose; Formation and properties of pectine . 3(51 
Properties of metapectine; Constitution and action of pectose . . . 302 
Pectous fermentation; Formation and properties of pectic acid . . . 363 
Formation of metapectic acid; Definition of the term isomeric . . . 304 
Development and ripening of a fruit viewed as a chemical process; Results 
of chemical researches into the changes fruits undergo during their devel- 
opment and perfection .......... 365 

Stages a fruit passes through during development and ripening . . . 307 



Fruits used for the preparation of fruit wines; Table of the average percen- 
tage of sugar in different varieties of fruit . . . ... 308 

Tables of the average percentage of free acid expressed in malic acid, and 
of the proportion between acid, sugar, pectine, gum etc., and of the pro- 
portions between water, soluble and insoluble substances . . . . 309 

Tables of the composition of the juice according to the content of sugar, pec- 
tine, etc., and of the content of five acid ....... 370 

Urape sugar or glucose; Acids 371 

Albuminous substances; Pectous substances; Gum and vegetable mucilage . 372 
Tannin; Pathological and physiological tannins ...... 373 

Inorganic constituents; Fermentation ........ 374 


Chief products of vinous fermentation . . . . . . . . 375 

Succinic acid; Glycerin .......... 376 

Carbonic acid; Alkaloid in wine ......... 377 


Methods of obtaining the juice or must from the fruit; W. O. Hickock's 

portable cider mill . . . . . . . . . . 378 

Crushing mill; Davis's star apple grinder 379 

Presses 880 

Farmer's cider press ........... 381 

Extra-power cider press .......... 382 

Revolving platform of the extra-power cider press; Improved racks . . 383 

Plain racks 384 

Apple elevator ............ 385 

Arrangement of a plant for making cider on a large scale .... 36 

Testing the must as to the content of acid and sugar; Determination of acid. 387 

Determination of sugar .......... 389 

Glucose 390 

Determination of the content of pure sugar in glucose ..... 391 

Anthon's table for finding the content of anhydrous sugar in saturated solu- 
tions of glucose; Cider from apples ........ 392 

Type of composition for pure ciders; Analyses of ciders by the United States 

Agricultural Department ......... 393 

Choice of varieties of apples for making cider ...... 394 

Composition of the apple 395 

Juice constituents of the apple; Gathering and sweating apples for the pre- 
paration of cider . . . . . . . . . . . 396 

Reduction of the apples to an impalpable pulp; Diversity of opinion as re- 
gards the crushing of the seeds ........ 397 

Pressing; Primitive method of laying the cheese; Substitution of hair cloth 

and cotton press-cloth for straw in laying the cheese. .... 398 

Extraction of the juice by diffusion; Objections urged against pasteurizing 
or sterilizing fresh apple juice; H. C. Gore's experiments to develop a 

method for sterilizing apple juice ........ 399 

Conclusions arrived at regarding the carbonating of fresh apple juice; Addi- 
tion of benzoate of soda to apple juice sold in bulk; H. C. Gore's investiga- 
tions of the cold storage of cider ........ 401 

Testing apple juice to be fermented; Filling the fermentation casks . . 402 

Fermentation of the apple juice, and pure cultures of yeast for this purpose. 403 

Fermentation funnel or ventilating funnel ....... 404 

First or tumultuous fermentation. ........ 405 

Clarification of cider ........... 106 

Additions to cider intended for export. ....... 407 

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

or red wine from cider ; Dr. Denis Dumont's directions for bottling cider . 408 



Manufacture of cider in the island of Jersey. . . . . . . 409 

Devonshire cider. . . . . . . . . . . .410 

Cider as a basis for artificial wines ........ 411 

Burgundy; Malaga wine; Sherry wine; Diseases of cider . . . .412 

Acidity in cider; Viscosity or greasy appearance of cider . . . .413 

Turbidity or lack of clarification of cider; Adulteration of cider; Minimum 
for the composition of pure cider ... . . . . . . 414 

Manufacture of brandy from cider ........ 415 

Preparation of the juice for distillation; Brandy from plums, damsons, etc. 416 

Distillation 417 

Pear cider; Preparation of " port wine " from cider ..... 418 
Quince wine ............ 419 


From small fruits; Means of preventing the wine from turning . . . 419 
Advantage of using a mixture of various juices; Means of improving the flavor 

and keeping qualities of the wine ........ 420 

Selection of the fruit; Expression of the juice; Fermentation; Clarification 

and drawing, off into bottles ......... 421 

Currant wine ............ 422 

Strawberry wine. ........... 424 

Gooseberry wine. ........... 425 

Gooseberry champagne .......... 427 

Raspberry wine . . . . . . . . . . . . 429 

Blackberry wine 430 

Mulberry wine; Elderberry wine; Juniperberry wine . . . . . 431 
Rhubarb wine; Parsnip wine; Wine from various materials. . . . 432 
From stone fruits; Cherry wine; Morello wine; Plum wine .... 433 
Sloe or wild plum wine 434 





Rules applying to all methods of preserving fruit 435 

French method known as Baine-Marie; Preservation of the flesh of the fruit 
without boiling. . . ...... ... 436 



Preparation of the fruit for preserving; Preservation of fine table pears; Pre- 
servation in air-tight cans. ......... 438 

Groups of canned articles embraced in the American trade lists; Fruits suit- 
able and unsuitable for canning 439 

Various styles of cans and jars ......... 440 

Manner of coating and lining the inside of tin cans; Manufacture of tin cans 

in the United States canneries 441 

Division of labor in the canneries; Preparation of the syrup. . . . 442 

Apparatus for the expulsion of the air by heating the cans; Cleansing and 
testing the cans. ........... 443 

Canning of tomatoes; Selection of a site for a canning establishment . . 445 
How contracts for a supply of tomatoes are made; Arrangement of a canning 
factory; Scalding the tomatoes ......... 446 

Skinning the tomatoes; Machines for filling the cans; Cappers and their 

work . . . . . . . 447 

Labeling the cans. ......... . 448 

Trials and vexations of a canner's life; Catchup ...... 449 

Tomato catchup ............ 450 

Walnut catchup ............ 451 

Gooseberry catchup; Horseradish catchup ; Fruit butter, marmalades and 
jellies; Fruit butter; Manufacture of apple butter ..... 453 

Preparation of raisine ; Marmalade ........ 454 

Derivation of the wood marmalade; Manufacture of marmalade on a large 
scale. ............. 455 

Quantity of sugar to be used; Secret of the great reputation the products of 

the principal American factories enjoy; Selection of fruit for marmalade . 456 
Apple pulp as a foundation for marmalade, and its preparation; Storage of 

fruit pulp 457 

Tutti-frutti; English marmalade; Jelly; Erroneous opinion regarding the 

quantity of sugar required in making jelly; Apple jelly without sugar . 458 
Use of the saccharometer in jelly boiling; Jellies from pears, mulberries and 

other small fruit 459 

Preparation of jelly from stone-fruit, quinces, rhubarb, etc ; French perfumed 

jelly 460 

Manufacture of apple jelly in one of the largest plants for that purpose; Ar- 
rangement of the factory 461 

Grating the apples and expressing the juice; The defecator and its object . 462 
The evaporator ............ 463 

Proper consistency for perfect jelly; Yield of jelly from a bushel of fruit . 464 
Saving of the apple seeds .......... 465 


The Alden Patent for evaporating fruit. ....... 465 

Theory of evaporating fruit 466 


Absorption of moisture by the air. ........ 467 

lieason why drying fruit in the oven must yield unsatisfactory results . . 468 
Chemical analysis of a parcel of Baldwin apples, showing the changes in the 

composition of the fruit by drying in the oven, and by evaporation . . 4('9 
Tower evaporators; The improved Alden evaporator ..... 470 

The Williams evaporator . . . . . . * . . . . 472 

Manner of operating the Alden evaporator ....... 474 

Table of intervals of time at which the trays must be placed in the evapora- 
tor; Handling and packing the evaporated fruit 475 

Kiln evaporators, described by H. T. Gould; Construction of a kiln . . 476 
Heating the kiln and appliances for that purpose . . . . . 477 

Arrangement of an evaporator having four or five kilns .... 479 

Selection of the varieties of fruit to be evaporated; Paring and bleaching ap- 
ples; Types of bleachers .......... 480 

Temperature to be maintained in the kiln ....... 481 

Manner of placing the fruit in the trays when drying in the tower evapora- 
tor; Treatment of plums after evaporating; Conversion of grapes into rais- 
ins; Mode of obtaining Malaga grapes; Evaporation of tomatoes . . 482 
Evaporation of various vegetables, and of potatoes ..... 483 

Sun-drying apparatus ........... 484 

French method of drying fruit in the oven ... .... 485 


Pickles; Manner of packing pickles; General rule for the preparation of pick- 
les 487 

Preparation of spiced vinegar ......... 488 

"Greening" pickles; Fruits and vegetables chiefly used for the preparation 
of pickles 489 

Mixed pickles; Picalilli; Pickled gherkins . ... . . 490 

Gherkins in mustard; Pickled mushrooms; Pickled onions, peaches, peas, 
and tomatoes ............ 491 

Pickled walnuts; Mustard; English method of preparing mustard; Substan- 
ces used for seasoning mustard ......... 492 

Gumpoldskircher must-mustard; Moutarde des Jesuites, French mustard; 
Ordinary mustard ........... 493 

Frankfort mustard; Wine mustard; Aromatic or hygienic mustard; Diissel- 
dorf mustard; Sour Diisseldorf mustard ....... 494 

Sweet and sour Kremser must-mustards; Moutarde de maille; Moutarde aux 
Apices; Moutarde aromatisee; English mustard. ..... 495 



Appert's method of canning meats; Cans used; Placing the prepared meats in 
the cans; Heating the cans and steam-chamber for the purpose . . . 496 



Object to be attained in operating according to Appert's method . . . 497 
Preparation of corned beef according to Appert's method; Meat biscuit ac- 
cording to Gallamond .......... 498- 

Soup tablets 499 

Beef extract; Quick salting of meat by liquid pressure; Quick process of 

smoking meat ^ 500 

Preparation of powdered meat; Preservation of fish 502 

Preservation of eggs . .......... 503 


Table I. Hehner's alcohol table. . 506 

Table II., which indicates the specific gravity of mixtures of alcohol and 
water * 509 

Table III. Proportion between the per cent, by weight and by volume of 
alcoholic fluids at 59 F 510 

Table IV. The actual content of alcohol and water in mixtures of both fluids 
and the contraction which takes place in mixing ..... 511 

Table V. For'comparing the different aerometers with Tralles's alcoholo- 
meter 512 

Determination of the true strengths of spirit for the standard temperature of 
59 F 5ia 

Table VI. Determination of the true strengths of spirit for the standard 
temperature of 59 F. (15 C.). 514 

Explanation of Table VI 519 

Table VII. Determination of the true volume of alcoholic fluids from the 
apparent volume at different temperatures; Explanation of Table VII. , 520 

Table VIII. Preparation of whiskey of various strengths from spirits of 
wine. ... t ......... 522 

Table IX. For the reduction of specific gravities to saccharometer per cent. 523 

Table X. Comparative synopsis of the aerometers for must generally used . 526 

Table XL Table to Oechsle's aerometer for must 527 

Table XII. Table to Massonfour's aerometer for must 527 

Table XIII. For comparing per cent, of sugar with per cent of extract and 
specific gravity 527 

Table XIV. For determining the content of per cent of acetic acid contained 
in a vinegar of specific gravity (according to A. C. Oudemans) . . 528 

Table XIV. For determining the content of per cent, of acetic acid con- 
tained in a vinegar of specific gravity (according to Mohr) . . . 529 

Table XVI. Comparison of the scales of Keaumur's, Celsius's and Fahren- 
heit's thermometers 530 

Index . . 531 





Ordinary vinegar consists of a weak solution of acetic acid 
in aqueous fluids prepared by the oxidation of alcoholic liquors 
by means of acetic acid bacteria, Bacterium aceti, of which 
there are many varieties, the best races being propagated by 
pure culture methods, and used for impregnating the alcoholic 
liquors to be fermented. The color of vinegar and, to a cer- 
tain extent, also its odor and taste are influenced by the ma- 
terials from which it is prepared. In this form it has been 
known from the earliest times, and it must have been used 
contemporaneously with wine, because it is evident that at the 
temperature of the Eastern countries, where the first .experi- 
ments with the juice of the grape were made, fermentation 
must have set in rapidly and the wine been quickly trans- 
formed into an acid compound. Vinegar is mentioned in the 
Old Testament, and Hippocrates made use of it as a medicine. 
That the solvent effects of vinegar were understood by the 
ancients, is shown by the well-known anecdote of Cleopatra, 
related by Pliny. To gain a wager that she could consume 
at a single meal the value of a million sesterces, she dissolved 
pearls in vinegar which she drank. This is also shown by 
the equally well known, but exaggerated account by'Livy and 
Plutarch, that Hannibal overcame the difficulties offered by 


the rocks to the passage of his army over the Alps, by dissolv- 
ing them with vinegar. Admitting the exaggeration, or the 
explanation which some give, viz.: that Hannibal used the 
vinegar by way of strategem, to incite his men to greater ex- 
ertion by the belief that the difficulties of the path were 
diminished, the case nevertheless shows that the solvent action 
of vinegar upon certain substances was well known at that 

Vitruvius also states that rocks which cannot be attacked 
by either fire or iron, will yield when heated and wet with 

Although there can be no doubt that vinegar was in very 
general use at an early period, there was no definite knowledge 
as to the cause of its production and the mode of its formation, 
and we are indebted to the much-abused alchemists for the 
first knowledge of its purification and concentration by dis- 

Gerber, who flourished in the eighth century, gives us the 
earliest description of 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. Basilius Valentinus, a monk and celebrated 
alchemist of the fifteenth century, knew that by the slow dis- 
tillation of vinegar, first a weak, and then a stronger product 
is obtained, and he was probably also acquainted with the 
process of obtaining strong acetic acid by distilling cupric ace- 
tate (verdigris.) In fact, for a long time this was the only way 
of preparing acetic acid, the result of the further rectification of 
the product being termed radical vinegar, spiritus Veneris, 
Venus' s vinegar, spiritus aeruginis, etc. 

Stael, in 1697, strengthened vinegar by freezing out some of 
its water. In 1702, he taught the method of obtaining strong 
acetic acid by neutralizing vinegar by an alkali, and distilling 
the acetate thus formed with oil of vitriol. The Count de 
Laragnais (1759), and the Marquis de Courtenvaux (1768), 
showed that the most concentrated acetic acid obtained from 


verdigris was capable of crystallization. Loewitz (1789) 
taught how pure, but weak acetic acid might be strengthened 
by passing it repeatedly over charcoal powder. It may thus 
be deprived of so much of its water that it crystallizes by cold. 
This crystallizable acetic acid is the strongest which it is pos- 
sible to obtain. Durande (1777), gave to it the name which 
it still bears, of glacial acetic acid. 

The formation of an acid body in the destructive distillation 
of wood was known as early as the seventeenth century. How- 
ever, it was for a long time not recognized as acetic acid, but 
considered 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 products formed in the destructive 
distillation of animal substances. 

Berzelius, in 1814, determined the exact chemical constitu- 
tion of acetic acid, and Saussure, in the same year, that of alco- 
hol. Dr. J. Davy observed that spongy platinum, in contact 
with vapor of alcohol, became 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 was formed, thus pointing out the fallacy of the 
opinion held by the chemists of his time that carbonic acid 
was one of the products of acetic fermentation. 

Schiitzenbach, in 1823, one year after the establishment by 
Dobereiner of the now generally accepted theory of the forma- 
tion of acetic acid from alcohol, introduced the quick process 
of manufacturing vinegar. 

Without detracting from the credit due to Schiitzenbach for 
the introduction of his method and the improvement in the 
process of manufacturing vinegar, it may be mentioned that as 
early as 1732, nearly a century before, the celebrated Dutch 
chemist and physician, Boerhave, made known a method for 
making vinegar from wine, which contained the principles of 
the quick process. 


Although it is now more than ninety years since the intro- 
duction of Schiitzenbach's process into practice, the manufac- 
ture 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 on a foundation clearly indicated by 
a knowledge of natural laws, many important improvements 
may surely be introduced in the manufacture of vinegar on a 
large scale, this being especially the case where it is uninter- 
ruptedly carried on with the use of suitable apparatus. Many 
manufacturers still work according to Schiitzenbach's original 
plan, i. e., they use an ^immense amount of labor for a per- 
formance which can be attained in a much simpler manner. 

Progress is essential in every business, but for several reasons 
it is especially necessary for the manufacturer engaged in mak- 
ing 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 manufacture of vinegar, of course increases the price 
the manufacturer has to pay for it. Another reason why the 
production of vinegar from alcohol becomes constantly more 
difficult is found in the great competition arising from the 
continued improvements in the manufacture of pure acetic 
acid from wood. Not many years ago it was considered im- 
possible to obtain entirely pure acetic acid from wood when 
manufacturing on a large scale, but the article produced at 
the present time may be almost designated as " 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," i. e., pure 80 to 90 per cent, acetic acid, obtained from 
wood, and which, when properly diluted, furnishes ordinary 
vinegar, will undoubtedly gradually supersede vinegar pre- 
pared from alcohol, it being considerably cheaper. And not- 


withstanding that the price of wood vinegar is declining every 
year, in regions where wood is plentiful and cheap its manu- 
facture is a remunerative industry on account of the many 
valuable by-products tar, wood spirit, charcoal obtained 
besides acetic acid. At the present time, for all industrial pur- 
poses where acetic acid is required, as for instance in the man- 
ufacture of tar colors, that obtained from wood is used, and 
the quantities consumed in the production of vinegar for do- 
mestic purposes becomes larger every year. 

But the manufacture of vinegar from alcohol and alcoholic 
liquids will nevertheless continue to flourish, because the pro- 
duct obtained from them possesses different properties from 
the pure acetic acid prepared from wood. Vinegar obtained 
from alcohol, and still more so that from fermented fruit juices, 
such as wine, cider, skins of pressed grapes, or from malt, con- 
tains, 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 " bouquet bodies," and which 
give to the vinegar an agreeable smell and taste entirely want- 
ing in acetic acid prepared from wood. These properties are 
so characteristic that any one gifted with a sensitive and prac- 
ticed 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 may, 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 pre- 
pared from alcohol or fruit juices, a similar relation existing 
here as between genuine and artificial wine. The latter may 
be made so that, as regards taste and smell, it nearly ap- 
proaches genuine wine, but a connoisseur will at once detect 
the difference. 

The principal defects of the manner of manufacturing vine- 
gar by the quick process in general use are not in the method 
itself, for that, as already indicated, corresponds entirely to the 
theoretical 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 practical execution of it, the losses of 
material being much more considerable and greater than 
absolutely necessary : the consumption of labor is 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. 

As will be explained later on acetic acid contains the same 
elements found in carbonic acid and water, and to judge from 
the results already attained by chemistry in building up com- 
pounds from their elements, a method will no doubt be found 
by which acetic acid can on a large scale be produced from its 
elements. It is difficult to predict the effect the discovery of 
such a process would have upon the life of all other methods 
of vinegar manufacture. In fact, acetic acid has already been 
prepared in this manner, but the method employed is not 
adapted for operations on a large scale. 



INDEPENDENT of the formation of acetic acid by destructive 
distillation, the chemical processes by which acetic acid in 
larger quantities is formed are at present quite well understood, 
and may be briefly explained as follows : 

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

C 2 H 6 + 2 = C 2 H 4 2 + H 2 

Alcohol. Oxygen. Acetic acid. Water. 


According to the above formula, acetic acid and water are 
formed by the action of oxygen upon alcohol, and hence the 
formation 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 them other 
bodies are formed from the alcohol, can in a vinegar manufac- 
tory be. readily detected 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, i. e., in its nascent state Dobereiner ob- 
tained a body which he called " light oxygenated ether " 
(leichter Sauerstoffather). Liebig later on studied this com- 
bination more accurately, and found that, as regards its com- 
position, it differed from that of alcohol only by containing two 
atoms less of hydrogen. He applied to it the term ''alde- 
hyde." Aldehyde is composed of C 2 H 4 0, and its formation is 
represented by the formula 

C 2 H 6 + 2 = C 2 H 4 2 + 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 ab- 
sorption of oxygen and, based upon these facts, Liebig estab- 
lished 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 atmos- 
pheric oxygen, one-third of the entire quantity of hydrogen 
contained in it is withdrawn, and aldehyde is formed. The lat- 
ter, however, immediately combines further with oxygen, and 
is converted into acetic acid ; the formation of vinegar from 
alcohol being, therefore, a partial process of combustion. 

From the present standpoint of our knowledge regarding 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. The latter process can also be illustrated by an equa- 
tion 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 chemico-physiological process with the co-operation of a 
living organism. Alcohol and oxygen alone do not suffice for 
this purpose, the presence of nitrogenous bodies and salts, be- 
sides that of an organism, being absolutely 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" 
or " vinegar yeast," consumes the alcohol, nitrogenous sub- 
stances 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 Niigeli 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 
being alone of importance to him. 

As is well known, organisms producing fermentation are 
named after certain products which they form in larger quan- 
tities, the organisms forming alcohol from sugar being, for in- 
stance, briefly termed "alcoholic ferment." In this sense we 
may also speak of a vinegar or acetic 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 
properties of forming large quantities of acetic acid are inher- 
ent only in this ferment. Small quantities of acetic acid are, 
however, also, constantly formed by other ferments, so that 
in examining products due to the process of decomposition 
induced by organisms, acetic acid will generally be 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 many seeds, and generally 
appears in the putrefaction of substances 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 farther processes of fer- 
mentation decomposed into butyric and acetic acids. 

Acetic acid is found in many animal juices, for instance, in 
meat juices, milk, sweat and urine. It also occurs in the 
fresh fruit of the tamarind. The processes which take place 
in its formation in these cases are not known, though it is 
very likely directly formed from certain varieties, of sugar. 

There is quite a large series of X'hemical processes in which 
certain quantities of acetic acid are formed. Sugar, starch, 
woody fibre and, in general, all compounds known as carbo- 
hydrates, when fused with caustic alkalies, yield certain quan- 
tities of acetic acid, and also by themselves when subjected to 
destructive distillation. Among the processes by which acetic 
acid is produced in a purely chemical manner, i. e., without 
the co-operation of organisms, the most interesting is that by 
which its formation is effected by the action of very finely 
divided platinum, the so-called platinum black, upon alcohol. 
Platinum black is readily prepared by boiling a solution of 
platinic chloride, to which an excess of sodium carbonate and 
a quantity of sugar have been added, until the precipitate 
formed after a little time becomes perfectly black, and the 



FIG. 1. 

supernatant liquid colorless. The black powder is collected 
on a filter, washed and dried by gentle heat. On account of 
the minute state of its division, this substance condenses within 
it several hundred times its volume of oxygen, and conse- 
quently 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 losing any of its inherent proper- 
ties, 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 replace that which 
has been withdrawn. The two actions then go on side by 

This can be illustrated by an apparatus similar to Fig. 1. 

It consists of a glass bell through 
the mouth of which a long funnel 
passes. The lower end of this funnel 
terminates in a fine point so that the 
alcohol may percolate very slowly. 
The vessel is placed upon supports 
within a dish in which is a saucer 
or small shallow basin containing 
the platinum black. The interspace 
between the bottom of the dish and 
the glass bell serves for the circula- 
tion of air in the latter. A short, 
time after the alcohol has been 
poured into the funnel an odor of 
acetic acid, arising from the acetic 
acid vapors which are generated, is 
perceived at the mouth of the bell. 

These vapors condense on the walls of the bell and trickle to 
the bottom, where they collect in the vessel in the dish. It is 
of advantage, for the success of the experiment, to have the 
alcohol heated to about 90 F. before pouring it in. By 
washing and igniting the platinum used for the oxidation of 
the alcohol, it can be again employed for the same purpose. 


Independent of the purely chemical methods which, with 
the exception of that by which acetic acid is produced by the 
destructive distillation of wood, are of no practical importance, 
the formation of vinegar, no matter what method may be 
adopted, can only be effected in the presence of certain organ- 
isms. It has long been known that organisms to which the 
term mother of vinegar has been applied, develop upon liquids 
containing, besides alcohol, certain other substances, for 
Instance, upon weak wine or beer, and this mother of vinegar 
has also been used for making vinegar on a large scale. To 
Pasteur, however, belongs the incontestable merit of having 
more accurately examined the relations of these organisms to 
the formation of vinegar. These examinations gave rise to 
his experiments on the diseased alteration of wine, which were 
later on superseded by his researches on the formation of wine 

Pasteur found that upon the surface of every fluid capable, 
by reason of its composition, of being converted into vinegar, 
organisms develop immediately after the commencement of the 
formation of vinegar. He recognized these organisms as fun- 
goid 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 schizomycetes has been applied. 

The Bacterium aceti, the name applied to this organism, 
consists of a single, generally globular or filiform cells, its 
special characteristic being its mode of propagation, which is 
effected by the division of the cell into two, and then a separa- 
tion 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, while other very little 


known bacteria must be considered as the cause of the so- 
called nitric acid fermentation, and again others appear in 
putrid fermentation. A special group of bacteria reaches de- 
velopment in animal organisms and gives rise to terrible dis- 
eases, some causing rinderpest, others tuberculosis and various 
other maladies. Cholera and other epidemics have 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 
manufacture in such a manner that disturbances shall rarely 
occur, and should they happen, that he may be able to remove 
them. It may therefore be said that the entire art of the man- 
ufacture 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 main- 
tained the process of the formation of vinegar will go on with- 
out disturbance, and the origination of new generations of 
vinegar ferment be connected with the conversion of certain 
quantities of alcohol into vinegar. 

Pasteur regarded the bacterial growth mentioned above as 
consisting of a single species. Hansen, however, showed in 
1878, that in the spontaneous souring of beer at least two dif- 
ferent species of bacteria can come into action, one of which 
he named Mycpderma aceti and the other Mycoderma Pasteur- 
ianum. At the suggestion of W. Zopf, he afterwards changed 
these names to Bacterium aceti and Bacterium Pasteurianum re- 
spectively. The number of species has been further increased 
by recent investigations, and among these acetic acid bacteria 
there are several, the activity of which is distinctly different, 
and the employment of a pure culture of systematical!^ selected 
species would be desirable in the manufacture of vinegar. 
Searching investigations into the chemical activity of the dif- 
ferent species of acetic acid bacteria would be not only oppor- 
tune in the interests of science, but also highly important in the 
practice of the vinegar industry. 




A. The Vinegar Ferment While but little is known about 
the origin of the vinegar ferment, experiments have shown 
these organisms to be everywhere distributed throughout the 
air and to multiply at an enormous rate when fluids of a com- 
position suitable for their nutriment are presented to them. 
A fluid especially adapted for this purpose is, for instance, 
throughly fermented ripe wine, its exposure in a shallow vessel 
at the ordinary temperature of a room being sufficient to in- 
duce the propagation of the vinegar bacteria reaching it from 
the air. 

The experiment is, however, certain of success only when 
made with ripe wine, by which is meant wine which shows but 
little turbidity when vigorously 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 
especially adapted for the nutriment of an organism, the sac- 
charomyces mesembryanthemum belonging to the saccharomy- 
cetes. It develops upon the surface of such wine as a thick 
white skin, which later on becomes wrinkled and prevents the 
growth of the vinegar ferment. A fluid well adapted for the 
nutriment of the vinegar ferment and which may be substituted 
for wine for its culture is obtained by adding 5 to 6 per cent. 
of alcohol and about J per cent, of malt extract to water. 

By exposing this fluid, or ripe wine at the ordinary tempera- 
ture of a room, best in a dish 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 will in a 
few days be observed. The wine soon exhibits the character- 
istic odor and taste of acetic acid, and in a few days assumes a 
somewhat darker color, and deposits a slight brownish sedi- 
ment consisting of decayed vinegar ferment. In 14 to 21 days 


the fluid is entirely converted into vinegar, i. e., it contains no 
more alcohol, but in place of it 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 testing the fluid, it will be found that the con- 
tent of acetic acid steadily decreases, 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 process above described of the destruction of the wine 

FIG. 2 

and its conversion into vinegar by a veil-like coating of vinegar 
ferment occurs most frequently, though a thick spume, the so- 
called mother of vinegar, may also happen upon the surface. 
This phenomenon will be referred to later on. 

On examining under the microscope a drop taken from the 
surface of the wine when the veil of vinegar ferment com- 
mences to form, a picture like that shown in Fig. 2 presents 
itself. In a somewhat more advanced stage, formations re- 
sembling 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 com- 
pletely filled with a large number of colorless globules, which 
are present either singly or in combinations of two, formations 
resembling chains or strings of beads being of rare occurrence. 
In many of the separately-occurring formations oval forms, gen- 
erally slightly contracted in the centre, are observed, this con- 
traction indicating the place where the splitting of one cell 
into two new cells takes place. By vigorously shaking the 
fluid before viewing 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 de- 
velopment, the globules strung together will be noticed to fall 
apart when at rest. Hence it may be supposed that in the 
propagation of cells by splitting, the newly formed cells ad- 
here together up to a certain stage, and later on separate in the 
fluid when in a quiescent state. Like 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 ferment, 
but differs from it in being less transparent, and of a brownish 
color. The propagation of the vinegar ferment takes place 
very rapidly, and it will be found in a few hours after the com- 
mencement of its development in all stages of life upon the sur- 
face of the fluid, it being possible to distinguish cells of from 
1.5 to 3.5 micromillimeters.* 

The vinegar ferment requiring free oxygen for its propa- 
gation, grows exuberantly only upon the surface of the nutrient 
fluids. By filling a bottle about four fifths full 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 

* One micromillimeter = j^ millimeter. 


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 experiment, and a few days after, shows but a slight in- 
crease in acetic acid, because the ferment has consumed the 
free oxygen present in the bottle, the essential condition for its 
further development 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 in- 
crease of cells takes place, and it may remain in this state for 
a long time without suffering destruction, but as soon as the 
conditions for its nutriment are again presented, propagation 
in a normal manner recommences. 

The great rapidity of propagation of the vinegar bacteria 
is shown by an experiment of some importance to the practice. 
Pour into a shallow vat, about three feet in diameter, a fluid 
suitable for the nutriment of the 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 froni 
the points where the drops of wine have been distributed. 
From this it will be seen that the culture of the ferment for 
the purpose of manufacturing vinegar offers no difficulties, 
provided all conditions for its propagation be observed. 

7?. Conditions for the Nutriment of the Vinegar Ferment. The 
conditions most favorable for the development of the vinegar 
ferment, and for converting in the shortest time the largest 
quantity of alcohol into acetic acid, have been determined by 
many observations and long experience in the practice. These 
conditions will first be briefly enumerated, and then the sep- 
arate points more fully discussed. 

For the vinegar bacteria to settle upon a fluid, and for their 
vigorous propagation, 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 

(atmospheric air). 

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

must be within certain limits. 

As regards the composition of the nutrient fluid itself, it 
must contain all the substances required for the nutriment of 
a plant of a low order, such substances being carbohydrates, 
albuminates and salts. Alcohol must be named as a specific 
nutriment 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 making vinegar must, however, not exceed a 
certain limit, a content of 15 per cent, appearing to be the 
maximum at which acetic fermentation can be induced. 
But even a content of 12 to 13 per cent, of alcohol is not very 
favorable for the vegetation of the vinegar ferment, and every 
manufacturer knows the difficulty of preparing vinegar from 
such a fluid. A small quantity of acetic acid in the nutrient 
medium 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 con- 
vert 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 impregnating a 
fluid consisting only of water and alcohol, a very small quan- 
tity of acetic acid is formed to be sure, but the ferment perishes 
in a short time it starves to death. A fluid suitable for its 
nourishment must, therefore, contain the above-mentioned 
nutrient substances, sugar, dextrine, or similar combinations 
occuring in wine, malt extract, and beer, being generally em- 
ployed as carbohydrates. These fluids further contain nitro- 
genous combinations which may serve as nutrient for the fer- 


inent, also considerable quantities of phosphates. Hence, by 
an addition of wine, malt extract, beer, or any fruit wine (apple 
or pear cider) to a mixture of alcohol and water, a fluid can 
be prepared that contains all the substances essential to the 
nutriment of the ferment. 

The necessary quantity of these nutrient substances, as com- 
pared with that of alcohol, is very small, since the quantity by 
weight of vinegar ferment required for the conversion of a very 
large amount of alcohol into vinegar is only a few fractions of 
one per cent, of the weight of alcohol used. Hence the manu- 
facturer may be very sparing with the addition of nutrient 
substances to the fluid to be converted into vinegar, without 
having to fear that the ferment will be stinted. 

The vinegar ferment is very sensitive to sudden changes 
in the composition of the fluids upon which it lives, and suf- 
fers injury by such changes which are recognized by dimin- 
ished propagation and a decrease in the conversion of alcohol 
into acetic acid. 

By transferring, for instance, vinegar ferment which had nor- 
mally vegetated upon a fluid containing only 4 to 5 per cent, 
of alcohol, to one with a content of 10 to 11 per cent., its pro- 
pagation, as well as its fermenting energy, decreases rapidly 
and remains sluggish, until a few new generations of cells have 
been formed which are better accustomed to the changed con- 
ditions. 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 nutriment of the vinegar ferment, however, 
must not be understood to consist simply in the consumption 
of sugar, albuminates and salts. It differs according to the 
composition of the nutrient medium, and is so complicated as 
to require very thorough study for its explanation. If, for in- 
stance, wine is converted into vinegar, and the composition of 
the latter compared with that of the original wine, it will be 


found that not only the alcohol has been converted into acetic 
acid and the fluid has suffered a small diminution of extractive 
substances and salts, which might be set down to the account 
of the nutriment of the ferment, but that the quantity of tar- 
taric, malic and succinic acids has also decreased, as well as 
that of glycerine, and of the latter even nothing may be pres- 
ent. Hence it must be supposed that the vinegar ferment 
derives nutriment also from these substances, or that the fer- 
menting activity acts upon them as well as upon the alcohol. 
There is finally the fact of great importance for the practice, 
but which has not yet been sufficiently explained, that the 
vinegar ferment develops more rapidly upon a fluid which, 
besides the req-uisite nutrient 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 
propagation and fermenting activity. In the practice it is 
aimed to accomplish 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 man- 
ufacture is based. 

Besides the above-mentioned factors, the temperature to 
which the ferment is exposed is of great importance as regards 
its development. The limits at which the propagation of the 
ferment and its vinegar-forming activity are greatest, lie be- 
tween 68 and 95 F. Above this limit the formation of 
vinegar decreases rapidly, and ceases entirely at 104 F. 
However, when the temperature is again reduced to 86 F., 
the ferment reassumes its activity. At a temperature exceed- 
ing 104 F. the ferment suffers perceptible injury ; heated to 
103 F. it becomes sensibly weaker, and at first propagates 
very slowly, regaining its original vigorous development only 
after several generations. When the temperature of the fluid 
is raised to 122 F. the ferment perishes. 

The ferment appears to be less affected by low temperatures. 


If the temperature of a fluid which shows an exuberant vege- 
tation of ferment is reduced to 50 F., the formation of vinegar 
continues, though at a much reduced rate. Special experi- 
ments have shown that when wine with a vegetation of fer- 
ment is converted into ice by being exposed to a temperature 
of 14 F., and then melted and heated to 59 F., the ferment 
recommences to grow and to form acetic acid. It must, how- 
ever, be remarked that while vinegar ferment in a state of 
development keeps up a slow vegetation when the fluid is re- 
duced to a low temperature, it is extremely difficult to culti- 
vate it upon a cold fluid. This is very likely the reason why 
acetic degeneration is not known in cold wine cellars, while 
in cellars with a temperature of over 59 F., this dreaded pro- 
cess can only be guarded against by the greatest care. 

Since the propagation 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 con- 
verted into vinegar as near the uppermost limit of 95 F. as 
possible. Experience, however, has shown that at this temper- 
ature disturbances are of frequent occurrence in -the genera- 
tors, and for this reason one of 86 to 89 F. is generally 
preferred. The process of the formation of vinegar itself ex- 
plains why disturbances may easily occur at a high tempera- 
ture. 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 quantity of alcohol 
is in a short time converted into acetic acid, and consequently 
so much heat is liberated that the temperature in the gener- 
ator 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, 
tne formation of vinegar ceases all at once, and on examining 
the thermometer 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 form- 
ation, playing in many cases a role in the practice of making 
vinegar, has to be mentioned. This is the so-called mother of 
vinegar, the term having very likely been applied to it on ac- 
count of its causing acetification when brought into a fluid 
suitable for the formation of acetic acid. The first botanical 
investigation of this substance was made in 1822 by Persoon, 
who described the organized skin developing on various fluids, 
and gave it the general name of Mycoderma, i. e., mucinous 
skin or fungoid skin. 

Kiitzing, in 1837, showed that the " mother of vinegar" is 
constructed of a number of minute dot-like organisms which 
are now called bacteria arranged together in the form of 
chains. These he classified as algae, and named them Ulvina 
aceti, and asserted quite positively that alcohol is converted 
into acetic acid by the vital activity of these organisms. 
Kiitzing's results, however, attracted but little attention because 
two years after their publication, Liebig appeared on the scene 
with his theory of acetic fermentation, which has already been 
referred to, in which no mention was made of the potency of 
living organisms, but the " mother of vinegar " was asserted to 
be a formation devoid of life, a structureless precipitate of 
albuminous matter. One of the reasons put forward in sup- 
port of this view was a chemical analysis of the " mother of 
vinegar" by the Dutch chemist, G. Mulder, who because he 
failed to discover the presence of any ash constituents, thought 
that it must be regarded as a compound of protein and cellu- 
lose. Mulder's statement was refuted in 1852 by R. Thomson, 
who showed that a. sample of " mother of vinegar" contained 
94.33 per cent, water, 5.134 per cent, organic matter and 0.336 
per cent. ash. 

The formation of mother of vinegar can always be success- 
fully attained by exposing young wine to the air until the 
commencement 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 con- 
stituting the mother of vinegar soon forms upon the surface. 

Mother of vinegar occurs so generally in young wine which 
is largely used for the preparation of wine vinegar, that its 
formation was considered as inseparably connected with that of 
acetic acid from alcohol, while actually it is only due to the 
peculiar 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. 


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. 

However, for the manufacture of acetic acid, and con- 
sequently of vinegar on a large scale, only two methods 
are available, viz., the preparation of vinegar from al- 
cohol by fermentation, or the production of acetic acid 
by the destructive distillation of wood. 

2. All alcoholic fluids formed by vinous fermentation of 

sacchariferous plant juices or fermented malt extracts 
are suitable for the preparation of vinegar by fermenta- 
tion. Specially prepared mixtures of water, alcohol 
and vinegar may also be used for the purpose, provided 
they contain small quantites of certain organic sub- 
stances and salts,. and not over 14 per cent of alcohol. 

3. Acetic 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 pro- 
pagation of this organism. 


4. Besides the substances mentioned in 2, the vinegar fer- 

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

5. In the acetic fermentation the greater portion of the al- 

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



THE formation of vinegar by fermentation being a chemico- 
physiological process, many and complicated chemical pro- 
cesses must take place in the fluid to be converted into vine- 
gar in order to produce all the combinations required for the 
propagation of the ferment. Attention cannot be too fre- 
quently called to the fact that from the standpoint of the manu- 
facturer, the regular propagation of the ferment is the main 
point of the entire manufacture, 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 nutrient 
substances (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 perceptible loss of alcohol will occur in the 
production. It would be erroneous to suppose that the con- 
version of alcohol into acetic acid and water is effected accord- 


ing to the formula given on p. 6, since 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 pro- 
cesses has been most thoroughly studied, it is found that from 
the sugar, besides alcohol and carbonic acid, large quantities 
of glycerine and succinic acid and probably other bodies ,are 
formed, which must undoubtedly be classed among the pro- 
ducts of vinous fermentation. Similar processes, no doubt, 
take place in acetic fermentation, and besides acetic acid and 
water other little-known products of fermentation are regularly 

According to the nature of the sacchariferous fluids sub- 
jected to vinous fermentation, small quantities of certain 
bodies called fusel oils are formed which are decidedly pro- 
ducts of fermentation. 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 judg- 
ment can be formed as to the material employed in its prepa- 

In the conversion of such a fluid, or of alcohol prepared 
from it, into vinegar, the fusel oils are also changed very 
likely oxydized 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 aro- 
matic 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 acetic fermentation, 
they being characteristic as regards the derivation of the vine- 
gar. Of the products of acetic fermentation, besides acetic 
acid, aldehyde and acetal are best known, these combinations 
appearing always, even in small quantities, in making vinegar 
according to the methods customary at the present time. 

Acetic Aldehyde or Acetaldeliyde, commonly called simply 
aldehyde (from alcohol dehydrogenatum), is obtained by oxidiz- 
ing spirits of wine by means of manganese dioxide (pyrolu- 


site) and sulphuric acid, or platinum black, in the presence 
of air, or if alcohol or ether be burning without a sufficient 
supply of air. It is also formed by heating a mixture of cal- 
cium acetate and calcium formate. It is contained in con- 
siderable quantities in the first runnings obtained in the 
manufacture of spirit of wine. 

To prepare pure aldehyde, 3 parts of potassium dichromate 
in small pieces are placed in a flask surrounded by a freezing 
mixture and a well-cooled mixture of 2 parts of spirit of 
wine, 4 of sulphuric acid, and 4 of water added. After con- 
necting the flask with a condenser the freezing mixture is re- 
moved ; a violent reaction 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 various other products are condensed and flow back, while 
the vapor of the aldeh} T de, after having passed through a de- 
scending condenser, is absorbed in anhydrous ether. 

Pure aldehyde thus obtained is a colorless liquid of the 
composition C 2 H 4 0. Its specific gravity is 0.800, and it boils 
at about 71.5 F. It has a pungent and suffocating odor, 
and is readily soluble in water, alcohol and acetic acid. Like 
all the aldehydes it is very easily oxidized and acts, therefore, 
as a powerful reducing agent. Thus, on heating it with a 
little ammonia and nitrate of silver, metallic silver separates 
outj coating the sides of the vessel with a bright mirror. It 
combines with ammonia, and forms a crystalline compound 
which has the peculiar odor of mice. 

Though it is likely that in the manufacture of vinegar by the 
quick process, besides aldehyde, acetic and formic ethers are 
formed, they are of comparatively little importance for our 
purposes. Of more importance, however, is acetal, the forma- 
tion of this combination affording an interesting insight into 
acetic acid. 

Acetal 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 con- 
verted into acetic acid, 60 percent, alcohol is poured upon the 
plate and the air in the bell-glass from time to time renewed. 
In a few weeks quite a thick fluid of an agreeable odor has 
collected upon the glass plate. This is collected and dis- 
tilled, the portion passing over at 219 F. being collected by 

Pure acetal is composed of C 6 H 14 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 oxidizing agents it is rapidly converted into acetic acid. 
Nitrate of silver in the presence of ammonia, however, is 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 2 , in which two atoms of hydrogen 
have been replaced by two molecules of the radical ethyl 
C 2 H 5 , hence thus 

" C 6 H U 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 molecules of ethyl in the combination. 

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

C 2 H,O aldehyde 
C 4 H 10 aldehyde ether 
C 6 H^6 2 acetal, 

or as a combination of aldehyde with ethyl alcohol, one mole- 
cule of water in the latter having been replaced by the alde- 
hyde : 


Ethyl alcohol: 2(C 2 H 6 H 2 0=C 4 H 10 O 
aldehyde C 2 H 4 O 
acetal C 4 H M 2 

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

Pure acetic acid, C 2 H 4 2 , cannot be directly obtained from 
vinegar, but only from acetates by methods which will be de- 
scribed later on. The strongest acetic acid which can be pre- 
pared is known as glacial acetic acid, from its crystallizing in 
icy leaflets at about 40 F. Above about 60 F. the crystals 
fuse to a thin, colorless liquid of an exceedingly pungent and 
well-known odor. Pure acetic acid is a powerful restorative 
when applied to the nostrils in impending fainting. It is the 
strongest of organic acids and nearly as corrosive as sulphuric 
acid. Applied to the human skin it acts as an irritant, causing 
redness and swelling, followed by paleness of the part, and, if 
its application be prolonged, it is followed by vesication and 
desquamation of the cuticle. It first whitens mucous mem- 
branes, then turns them brown, causing meanwhile a severe 
burning pain. Highly concentrated acetic acid is a solvent of 
many volatile oils and resins, and in practice its high con- 
centration is tested by its ability to dissolve lemon oil, 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 Oudemans ....... 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 u 68.0 " 

1.0198 77.0 " 

1.0480 79.0 ki 

Mixtures of acetic acid and water show a peculiar behavior 
in regard to their specific gravity, the latter rising 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 per cent, of water shows the same specific 
gravity as the anhydrous 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 mix- 
ture, 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 found considerable ap- 
plication 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, besides acetic acid, are formed in abundance 
in the destructive 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 '\0 

C 2 H 3 J C 

TT -| 

whereby the acetic acid is considered as water ^r V in which 

one atom of hydrogen is replaced by the compound radical 
C 2 H 3 = acetyl. 

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

C 2 H 3 

or sodium acetate. 

If this atom of hydrogen is replaced by a univalent com- 
pound radical, for instance, by methyl CH 3 , or ethyl C 2 H 5 , 
the so-called compound ethers are formed. 

CH 3 
C 2 H 3 

Acetic acid methyl ether. Acetic acid ethyl ether. 

If a bivalent metal or compound radical yields a neutral 
combination with acetic acid, the substituted hydrogen in two 
molecules of acetic acid must evidently be replaced by this 
bivalent metal, for instance : 

Ca \ Q 

2(C 2 H 8 0) j u * 

Neutral calcium acetate. 

Theoretical Yields of Acetic Acid In industries based upon 
chemical processes a distinction is made between the theoreti- 
cal 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 which such losses are taken 
into account^ the average being ascertained by long-continued 


comparison of daily yields. The closer the practical yield ap- 
proaches the theoretical one, the more suitable the method 
pursued in the production evidently is, and thus the manu- 
facturer, 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 composi- 
tion 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 6 0, or an atomic weight 
of 46, because : 

C 2 = . . .24 
H 6 = 6 

= . . .16 

Make . .46 

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

C 2 = . ' . .24 
H 4 = . . . 4 
2 = . . .32 

Make . . 60 

Hence from 46 parts by weight of alcohol 60 parts by 
weight of acetic acid may be formed, or by taking 100 
parts of alcohol it follows that 100 parts by weight of alcohol 
must yield 130.43478 parts by weight of acetic acid. This in- 
crease 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 hydrogen are themselves oxidized to water by the absorp- 


tion 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 parts 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 contained 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 escap- 
ing from well-conducted vinegar generators have shown that 
on an average only one-quarter of the entire content of oxygen 
is consumed in the formation of vinegar, hence four times the 
theoretically 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 

A vinegar generator, on an average, converts daily 3 litres 
of alcohol into acetic acid ; 3 litres 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 opera- 
tion. * 

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

Since the formation of vinegar has theoretically to be con- 
sidered as a process of combustion, in which of 4G 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 hydro- 
gen, are consumed, the quantity of heat liberated by the con- 
version of 100 parts by weight of alcohol into acetic acid can 
also be calculated. 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 kilogrammes of water from C. to 1 C., or 
1.48 kilogrammes from C. to boiling, and thus a consider- 
able 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 manufac- 
turer 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 requires a large supply ; but the generators in general 
use in the quick process are by no means so arranged as to be 
adequate to the theoretical demands. In fact it may be said 
that most of them allow only a limited change of air and con- 

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


sequently work slower than they actually should. That the 
generators now in use are deficient is conclusively proved by 
the numerous constructions which have been proposed, especi- 
ally in modern times, whose chief aim is to afford a free pas- 
sage to the air. 

The fact that considerable heat is developed in the interior 
of the generator deserves consideration in connection with the 
heating of the manufactory. If the temperature in the latter 
is so high as nearly to approach the acme, 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 be 
increased to such an extent as to exceed this acme, 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 
so much as when the correct conditions are observed. Bat 
while 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 

The acme 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 tem- 
perature of the workroom must, however, be kept sufficiently 
low, so that the acme in the interior of the generator may not 
be exceeded. 

Another factor may here be mentioned. The closer the 
temperature in the interior of the generator approaches the 
acme and the quicker the supply of air, the more alcohol and 
acetic acid are lost by evaporation, or in other words, the 
smaller the yield of acetic 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 arrange- 
ment of the workroom. By regulating the change of air so 


that it is not greater than absolutely necessary, the air will 
soon become so saturated 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 
acme of temperature and a vigorous change of air in them, 
and in this case must submit to the increased losses insepar- 
ably 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 production in use. 

In a vinegar factory occur many unavoidable losses, the 
sources of which have been indicated in the preceding explana- 
tions ; alcohol and acetic acid evaporate, and further a portion 
of them is entirely destroyed by too much oxidation. Now a 
loss 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 some vine- 
gar factories is not less than from 15 to 20 percent., and may 
even be as much as 30 per cent. 

These enormous losses of material conclusively prove the 
defectiveness of the processes in general use and the urgent 
necessity for reformation. The experiments made for this 
purpose, and which have been especially directed towards a 
remodeling of the apparatus used, cannot be considered en- 
tirely satisfactory, though they were partially instituted by 


practical manufacturers, who, however, lacked the necessary 
theoretical knowledge. 

The principal requirement is to provide the generator with 
a suitable ventilator, which will allow of the passage of ex- 
actly the quantity of air required for the conversion of the 
alcohol into acetic acid, and is so constructed that the vapors 
of alcohol and acetic acid (or at least the larger portion) car- 
ried away by the current of air are condensed and thus re- 

A vinegar generator has frequently been compared to a fur- 
nace, and in continuation of this comparison it may be said, 
that the construction generally used is a furnace lacking every 
arrangement for the regulation of combustion. In such a fur- 
nace as much fuel is burned as corresponds to the quantity of 
oxygen entering, while in a furnace of suitable construction 
the combustion of fuel can be accurately regulated by increas- 
ing or decreasing at will the supply of air by means of a 
simple contrivance. 

A vinegar generator of suitable construction should be pro- 
vided with a similar arrangement. If the thermometer on the 
apparatus shows too low a temperature hence too slow a pro- 
cess of oxidation the course of the operation can in a short 
time be accelerated 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. 




FROM what has been previously said, two methods of man- 
ufacturing vinegar can only be distinguished, namely, by 
fermentation and by destructive distillation. It has, however, 
been deemed advisable to describe separately the old or slow 
process by fermentation and the new or quick process. The 
The various methods employed for the manufacture of vine- 
gar may therefore be designated as follows : 

1. By fermentation according to the old or slow process. 

2. By the quick process, or manufacture by fermentation 
with the application of improved methods in keeping with 
our present knowledge of chemistry. 

3. Manufacture of wood vinegar, or the preparation of acetic 
acid by destructive distillation. 

4. The preparation of pure acetic acid from acetates. 

It would seem proper to commence the description of the 
manufacture of vinegar with the old or slow process, but for 
reasons of an entirely practical nature, it has been concluded 
not to do so, and the quick process will be first considered. 

Since alcoholic fluids, directly formed by the vinous fer- 
mentation of sacchariferous plant juices, possess the property 
of changing, under circumstances favorable to acetic fermenta- 
tion, 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 juices 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 
indirectly used for the preparation of vinegar, since solutions 
of either can be brought into vinous fermentation, and the re- 
sulting 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 
therefore 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 con- 
tains a certain quantity of alcohol, and can thus be directly 
converted into vinegar. 

Alcohol forming ultimately the material for the manufacture 
of vinegar, the direct use of dilute alcohol became obvious. 
By the employment of a suitable process, i. e., one correspond- 
ing to the laws of acetic 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 process now in general use. 
Hence, as previously stated, two principal methods of manu- 
facture may be distinguished, viz. : the old or slow process, 
which requires more time, and the new, or quick process. 

In the old process many modifications are found, which are 
partially based upon old usage and partially upon the differ- 
ence 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 6 per cent, of alcohol but a large 
quantity of extractive substances, again require different treat- 
ment from grape wine, etc., so that, in a certain sense, it may 
be said there are as many different methods of making vin- 
egar 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 fre- 
quently only present in very minute quantities, nevertheless 
exert considerable influence upon its properties. 

Even vinegar obtained from dilute alcohol shows differ- 
ences in odor, which depend on the material used in the pre- 
paration of the specific alcohol. Potato alcohol always con- 
tains traces of potato fusel oil (amyl alcohol), while other 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 oxidized and converted into combinations 
distinguished by their peculiar and very strong odor. 

Though these bodies occur in vinegar in such minute quan- 
tities that they can scarcely be determined by chemical analy- 
sis, 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 pronounced, and extend not only to the odor, 
but also to the taste. Besides a specific odoriferous principle, 
every kind of wine contains oenanthic ether, tartar, tartaric 
and succinic acids, glycerin, and a series of extractive sub- 
stances not thoroughly known. The odoriferous substances 
and the oenanthic ether also undergo alteration in the oxida- 
tion of alcohol, and are converted into other odoriferous com- 
binations with suclx a characteristic odor that wine vinegar 
can at once be recognized as such by it. On account of the 
presence of so many substances each 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 pos- 
sess definite properties. 




IN 1823 Schiitzenbach conceived the idea that by greatly 
enlarging the relative surfaces of contact Of the alcoholic solu- 
tion and air containing oxygen, the process of acetification 
would be greatly facilitated. His experiments proved suc- 
cessful, and soon after the quick vinegar process was generally 
adopted. Analogous 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 
contrived. 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, present- 
ing a large surface, 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 acquiring 
from the liquid all the substances required for its nutriment 
and propagation, 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 being the same in both cases. 

It will be seen that the generator, technically called "grad- 
uator," used in the quick process may be compared to a fur- 


nace in which the fuel (in this case the alcoholic fluid) is in- 
troduced from above and the air from below. The spaces 
between the shavings, etc., may be compared to the interstices 
of a grate, combustion taking 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. 

Each generator, as previously stated, requires about 0.4 liter 
of air per second, which must ascend uniformly from below 
through the mass of shavings, etc. At the first glance this 
would seem very simple, but its practical execution is accom- 
panied by many difficulties, and hence a large number of vari- 
ous constructions of generators have been proposed by which 
this object is claimed to be best attained. 

Generators A peculiarly constructed vessel, called the gen- 
erator, is required for the production of vinegar by the quick 
process. It is divided into three spaces above one another, 
the uppermost serving for the division of the alcoholic liquid 
into many small drops ; in the center one, which forms the 
largest part of the apparatus, the alcoholic liquid is converted 
into vinegar, while the lower one serves for the collection of 
the vinegar. 

The best form of the generator is that of a truncated cone. 
This form offers to the alcoholic liquid in its passage from the 
upper part of the generator the opportunity of spreading over 
a constantly increasing surface, and by thus coming in con- 
tact with the fresh air entering the lower part of the apparatus 
its oxidation must evidently be promoted. The current of air 
in passing from below to above yields a certain portion of its 
oxygen in the lower part of the apparatus, and if it were 
allowed to ascend in a vessel of a purely cylindrical shape, the 
alcoholic fluid running down would come in contact with air 
quite poor in oxygen. Hence this evil must be sought to be 
overcome by the acceleration of the motion of the air upwards, 
which is accomplished by giving the vessel the form of a 
slightly truncated cone. 



Fig. 3 shows a common form of generator. It consists of 
the wooden vat K provided with a perforated false bottom L 
a few inches from the bottom, and another S, similar in struc- 
ture, at the same distance from the top. The aperture A 
serves for the discharge of the fluid collecting underneath the 
false bottom L. The cover D, the arrangement of which will 
be described later on, serves for regulating the drought of air 
in the generator. In the lower part of the generator, holes, O r 

are bored. These holes are intended for the entrance of air, 
and in number may be as many as desired, since the regula- 
tion of the current of air is not to be effected on the lower 
portion of the apparatus, but on the cover. 

For the construction of the generator wood thoroughly 
seasoned and as free as possible from knots should be used. 
Formerly oak was largely employed for the purpose but, be- 
sides its being too expensive, it has the disadvantage of be- 


ing so rich in extractive substances that a generator con- 
structed of it, has to be several times lixiviated with water 
before use, as otherwise the vinegar prepared in it would for 
a long time acquire a disagreeable tang and dark color. 
Larch is an excellent wood for the construction of generators. 
In this country pitch pine is largely used, and is well adapted 
for the purpose, as it is cheap and readily obtainable every- 
where. It is claimed by some manufacturers that the pitch 
pine protects fermentation in generators constructed of it from 
the influence of rapid variations in temperature which are of 
frequent occurrence in portions of this country. 

The hoops of the generators, as well as all other metallic 
parts in the factory, should be coated with good linseed-oil 
varnish or asphaltum lacquer, and care should be had imme- 
diately to repair any injury to this coating, as otherwise heavy 
rusting is caused by the vapors of acetic acid contained in the 
air of the work room. 

There is considerable variation in the dimensions of the 
generators, some having only a height of 5 feet, with a lower 
diameter of 3 feet 3 inches, and others again a height of 20 feet 
or more, with a diameter of up to 6J feet. The small gen- 
erators have the disadvantage of rapidly yielding heat to the 
exterior, and hence a correspondingly high temperature must 
be maintained in the workroom in order to keep up the proper 
degree of heat in their interior. On the other hand, generators 
of considerable height have the drawback of the shavings, 
etc., with which the center space is filled, becoming strongly 
compressed by their own weight, thus obstructing the proper 
passage of the air. It has been sought to overcome this evil 
by placing several false perforated bottoms in the generator, in 
order to divide the weight of the filling into as many smaller 
weights as there are false bottoms. But this arrangement is 
also attended with inconveniences, it being difficult to main- 
tain a sufficiently strong draught of air in generators of such 

Some manufacturers hold that the production of very 


strong vinegar containing 11 to 12 per cent, of acetic acid is 
only possible in very tall generators. This opinion is, how- 
ever, unfounded, the manufacture of very strong vinegar being 
just as well or rather better effected in small generators than 
in those twenty feet or more high, which besides are very 

The manufacture of vinegar should be carried on in a room 
with a low ceiling, since even with the best heating arrange- 
ment the temperature near the ceiling is always much higher 
than on the floor. However, with the use of generators 20 
feet high, the ceiling of the work room must be at least 26 
feet high, which makes it impossible to maintain a uniform 
temperature, as the difference between the upper and lower 
parts would frequently amount to more than 25. 

The most suitable generators are very likely those with a 
height not exceeding 10 feet, and a lower diameter of about 45 
inches and an upper one of about 35 inches. A large diameter, 
to be sure, contributes towards the maintenance of a uniform 
temperature in the generator, but it has the disadvantage of 
making it difficult for the air to ascend uniformly through all 
parts of the filling. This drawback is sought to be evercome. 
by placing in the center of the generator a tube open above and 
below and provided on the sides with holes. Such tube, how- 
ever, does not produce the intended favorable effect upon the 
draught of air in the parts of the filling surrounding it, expe- 
rience having shown that the greater portion of the warm cur- 
rent of air ascending in the interior takes the nearest road to 
the top, i. e., through the tube, without passing sideways into 
the filling. Every generator of suitable construction should be 
provided with a well-fitting cover. In this cover, Fig. 4, are 
bored, in concentric circles, holes which are intended for 
draught apertures. If the draught of air in the interior is too 
great, it can be at once diminished by closing a number of 
these holes, it being even possible to direct it towards a cer- 
tain portion of the filling. This arrangement is, however, only 
available when the false bottom to be described later on is 



either not used or provided with a number of short vertical 
tubes which permit the passage of the air. 

Many generators are provided with a number of obliquely 
bored apertures below the false bottom through which the air 
can escape. This is, however, attended with the disadvantage 
that a regular draught of air only takes place in the outer layers 
of filling next to the walls, while it is not sufficiently strong 
in the center of the apparatus. It is also incorrect to have but 
one air aperture in the cover, which can be made larger or 
smaller by means of a slide. In a generator thus arranged, the 

FIG. 4. 

current of air entering below will naturally pass chiefly through 
the conical portion of the filling, the base of which is formed 
by the lower false bottom and the apex by the draught aper- 
ture in the cover. The lower portion of the filling, which 
embraces this cone, remains without sufficient ventilation and 
is ineffective as regards the oxidation of alcohol. 

In Figs. 5 and 6 the hatched surfaces terminated by the 
dotted lines illustrate the portions of the generator in which, 
with the use of many apertures below the false bottom and a 
single one in the center of the cover, the. regular current of air 



from below to above passes. Although a current of air takes 
place outside of these lines, it is in most cases too weak, and 
consequently the entire available space of the generator is not 
sufficiently utilized. 

FIG. 5. 

FIG. 6. 


Each generator may also be entirely open below and stand 
in a shallow tub, which serves for the collection of the vinegar. 
Generally, however, the lower portion of the generator itself is 
used for this purpose, and is provided with an arrangement for 

FIG. 7. 

the occasional discharge of the collected fluid. This can be 
effected either by a spigot fixed immediately above the bottom 
or, as in Fig. 7, by a glass tube, which bends upwards nearly 
as high as the air-holes and then curves downward so as to dis- 



charge the liquid, when it rises as high as the shelf in the 
interior of the apparatus, into an appropriate vessel placed to 
receive it. Simple as this arrangement is, it is scarcely suit- 
able in the practice on account of its being too liable to break- 
age, and hence it is better to provide the generator with an 
ordinary spigot, and prevent the vinegar from rising too high, 
by boring about J inch below the draught apertures a hole 
in which is fitted a pipe leading to a tub. The vinegar rising 
to the height of this pipe will commence to run off, and thus 
give warning to empty the generator by opening the spigot. 

In generators of older construction a strong hoop is fixed 
about one foot from the top, on which is placed a perforated 
disk which serves for distributing the alcoholic fluid as uni- 
formly as possible over the entire filling. The disk, Fig. 8, is 
perforated with numerous holes (about 400 with a disk diam- 
eter of 3 feet) arranged in concentric circles. These holes are 
loosely filled with cotton wick or packthread, a knot being 
made at the top end to keep them from falling through. The 
threads reach down to the shavings, and serve the double 
purpose of conducting the liquid equally through the body of 


the generator and also of stopping it from passing too rapidly 
through it (see Fig. 9). It is important to pack the disk so 
tightly against the walls of the generator that none of the 
liquid can percolate, which is best effected by a packing of tow, 
and coating this with a mixture of equal parts of wax and 
rosin. The dripping of the alcoholic fluid through the disk 
taking place uniformly only when the latter lies perfectly hori- 
zontal, great care must be exercised in placing the generator. 
To prevent warping several strong cross-pieces are inserted in 
the lower side of the disk. 

As previously mentioned the current of air must pass through 

FIG. 9. 

all portions of the filling, and for this purpose seven short glass 
tubes, r (Fig. 8), about f inch in diameter, are inserted in the 
disk. These tubes are so arranged that one is in the center of 
the disk and the others in a circle equidistant from the center 
and the periphery. Upon the disk is placed the well-fitting 
cover, provided with an aperture for the passage of the air. 
This aperture, about 3 inches square, is provided with a well- 
fitting slide, so that it can be made larger or smaller at will. 
As previously stated, it is more suitable to provide the cover 
with a large number of draught holes arranged in concentric 
circles and to fit each hole with a wooden stopper. By with- 
drawing or inserting the stoppers the draught of air can then 
be properly regulated. 

To effect the influx of air from below in such a manner that 
it takes place not only through the draught holes in the circum- 
ference, but also assures its conveyance to the center of the 
apparatus, it is recommended to insert in the center of the 
lower part in which the fluid collects a tube, R, Fig. 10, open 



at both ends and protected above by the hood H against the 
dropping in of alcoholic liquid. 

A uniform distribution of the alcoholic liquid upon all por- 
tions of the filling of the apparatus would be effected if about 

FIG. 10. 

the same quantity of liquid dripped from all the threads. This 
being, however, difficult to attain, it has been sought to give 
the disk a more suitable arrangement, which consists, for in- 
stance, in the insertion of small wooden tubes with a small 

FIG. 11. 


aperture on the side (Fig. 11). This arrangement, though 
very suitable in itself, becomes, however, useless in case of the 
slightest warping of the disk, a number of the tubes being 
then raised so high that no fluid runs through them, while it 
passes in a full stream through the others. 



These drawbacks connected with the use of a disk can be 
somewhat diminished by the employment of a so-called " tilt- 
ing trough " (Figs. 12 and 13), which is arranged as follows : 

Upon a perfectly horizontal axis is placed a rotatory, trough- 
like vessel divided by a partition into two equal parts. 

If the tilting trough is in the position shown in Fig. 12, the 
alcoholic liquid runs through the cock, placed above, into the 
partition marked 1. 

As soon as this partition is filled to a certain height it turns 
ovef in consequence of the disturbance of the equilibrium of 
the trough and assumes the position shown in Fig. 13. In 
this position partition 2 is gradually filled with alcoholic 
liquid ; the trough then tilts back into position 1, and so on. 

FIG. 12. 

FIG. 13. 

It will be seen that with the assistance of such a tilting 
trough the same quantities of liquid can always be poured out 
at certain intervals, and that this arrangement can be used for 
distributing the alcoholic liquid upon the disk, the latter in 
this case being best provided with holes having the form of an 
inverted cone. The apex of this cone forms a very narrow 
aperture through which the alcoholic liquid poured upon the 
disk trickles in very thin jets upon the filling of the generator. 

But even this arrangement is not free from objections, it 
working entirely satisfactorily only as long as the disk remains 
in a perfectly horizontal position. In the more modern con- > 
structions of vinegar generators the disk is generally entirely I 



omitted and the distribution of the alcoholic liquor effected by 
a so-called " sparger," similar to the one used in beer brewing 
for sprinkling malt residues. The sparger is arranged like a 
simple turbine, and is moved by reaction in the direction 
opposite to that in which the discharge of the fluid takes place. 
Spargers used in vinegar factories can be constructed only of a 
material indifferent to the action of acetic acid, such as wood, 
glass, hard rubber, etc. Their construction will be understood 

FIG. 14. 

from Figs. 14 and 15, showing a view from above and a cross- 

Into a hollow cylinder of wood are screwed four thin wooden 
tubes, closed at both ends and perforated ^lengthwise with 
numerous small holes. The tubes are so arranged that all the 
holes are directed toward one side. The basin in the center is 
closed on top by a glass tube about 20 inches long and of 
sufficient width to allow of the passage of as much fluid as can 
at one time run off through all the lateral tubes. 



The principal requisite of the correct working of the sparger 
is that it revolves with ease around its vertical axis. This is 
effected by placing in the center of the vessel a glass pin drawn 
out to a fine point and running in a small glass step. The 

FIG. 15. 

vertical glass tube is guided in a sharp-edged wooden ring 
fastened to a stay placed upon the cover of the generator (Fig. 
16). The sparger finds its center of motion upon a strip in- 
serted in the direction of the diameter of the generator. This 
strip is placed at such a height that the sparger can move 


freely between it and the cover of the generator. The sparger 
being in position as shown in Fig. 16, a funnel-shaped vessel, 
through which the alcoholic fluid is poured in, is placed upon 
the glass tube. 


By now pouring through this funnel-shaped vessel the alco- 
holic liquid in a sufficiently strong stream, so that during its 
influx the glass tube remains filled, it passes in fine jets 
through the lateral openings, and, the sparger revolving in an 
opposite direction, is distributed in the form of a fine spray 
over the filling in the generator. 

The use of the sparger overcomes the difficulties frequently 
occurring with the disk, especially as regards the position of 
the latter, and the circulation of air through the apparatus also 
takes place in a perfectly uniform manner. A number of 
apertures in the cover of the generator serve also here for the 
regulation of the current of air. 

A thermometer is an indispensable adjunct to a generator, 
and should be so placed that the temperature prevailing in the 
apparatus, and especially in the center, can be readily read 
off. This is best effected by introducing at about half the 
height of the apparatus, through an obliquely bored hole in 
one of the staves, a glass tube closed at the lower end and 
reaching to the center of the filling. This tube serves for the 
reception of a thermometer fastened to the lower end of a stick 
of wood. The latter projects from the glass tube, so that the 
thermometer can be quickly drawn out and the temperature 
read off. 

Filling the generators. The space between the upper disk 
and lower false bottom is filled with a material offering a large 
surface for the distribution of the alcoholic liquid. Pieces of 
charcoal and of pumice washed in hydrochloric acid and well 
rinsed in water to remove empyreurnatic substances, which 
would render induction of acetic fermentation impossible, 
have been used for the purpose. Small pieces of cork and 
cork waste have also been recommended for filling. This 
material absorbs liquids like a sponge, but when sucked full 
does not press evenly together, dry places being thus formed 
during the operation. Corn cobs thoroughly dried and finely 
divided may be used to advantage, especially in the manufac- 
ture of wine and cider vinegar. Grape stems are still occa- 


sionally used. They actually present a very large surface 
but, independent of the fact that they cannot be everywhere 
obtained in sufficient quantities, they have the drawback of 
becoming in a short time so firmly compressed as to prevent 
the free passage of air. 

Beechwood shavings, however, are now almost generally em- 
ployed for filling the generators. Indeed, beechwood presents 
many advantages: It can be had easily and is cheap; it curls 
well and stands without breaking for a length of time. White 
woods will curl as well, but they will not stand so well as 
beech ; resinous woods are not porous enough, and besides 
their rosin is objectionable, as it may partly dissolve in the 
vinegar ; oak wood does not curl as well and contains too 
much coloring matter and tannin. 

The beech shavings are generally made in special factories. 
They consist of wooden bands about 0.02 inch thick, 1 J inches 
wide, and 16 to 20 inches long. They are rolled into close 
spirals by a special machine, and each shaving, according to 
the above dimensions, presents a surface of about 62 square 
inches. Now, as a generator of moderate size contains many 
thousands of such shavings, it will be readily seen that the 
surface over which the alcoholic fluid is distributed is an 
extraordinarly large one. 

A shaving of the stated dimensions represents in a rolled 
state a cylinder with a volume in round numbers of 1.7 cubic 
inches. By allowing an interspace of .85 cubic inch between 
the shavings, 1.7 -f- 0.85 = 1.92 cubic inches space is required 
for each shaving. The space to be filled with shavings in a 
generator 3.28 feet in diameter and 6.56 feet high is equal to 
55.44 cubic feet, and hence 58,000 shavings, with a total sur- 
face of 22,733.56 square feet, are required for the purpose. 
Now suppose only 5 per cent, of this surface is continually 
active in the formation of vinegar, we have still a surface of 
over 1075 square feet at our disposal. But the active surface 
would seem to be actually much smaller even with the most 
favorable working of the generator, as otherwise the average 


quantity of alcohol daily converted into acetic acid in a gen- 
erator would be much larger than is actually the case. 

Beechwood shavings contain a considerable quantity of ex- 
tractive substances, which if not removed, would for a long 
time impart a disagreeable tang (woody taste) to the vinegar. 
Hence it is recommended to lixiviate the shavings in water 
repeatedly renewed, in order to get rid of the substances 
soluble in cold water, and remove the last traces of them by 
treatment with steam. 

This steaming is best effected in a large tub or vat, which is 
later on to be used as a generator. The shavings are thrown 
in loosely and covered with a loaded lid. A steam-pipe is 
introduced through a hole near the lid, and the tap-hole near 
the bottom is opened. The steam-pipe being connected with a 
boiler, in which prevails a tension of 1J to 2 atmospheres, the 
steam-cock is at first opened but slightly, to prevent the steam 
entering with great force from throwing off the lid, or even 
bursting the vessel. In the commencement of the operation 
the steam condenses on the shavings, but after some time the 
vessel becomes very hot, and a dark-colored fluid, consisting 
of almost boiling water charged with extractive substances of 
the wood, begins to run off. After continuous steaming for 
about 20 to 60 minutes according to the size of the vessel 
the fluid running off becomes clearer until finally clear water 
is discharged, which is indicative of the removal of the 
extractive substances soluble in water. 

Although not absolutely necessary, it is advisable to dry the 
steamed shavings. When air-dry they still contain about 20 
per cent, of water, which in the subsequent " acetification " of 
the generator must be replaced by vinegar. Hence it is 
recommended to dry the shavings completely by exposing 
them for some time to a current of air of 194 to 212 F. 

In a factory provided with a central heating apparatus * in 
the cellar, this drying of the shavings can be effected without 

*The arrangement of a central heating apparatus will be described later on in 
speaking of the arrangement of the factory. 


difficulty, it only being necessary to put them in a vessel with 
a perforated bottom and open on top, and place the vessel 
over an aperture of the register through which the hot air 
from the heating apparatus ascends, closing all other apertures. 

As perfectly dry wood absorbs with avidity moisture from 
the atmosphere, the shavings thus dried should immediately 
be brought into another vessel and, while still hot, moistened 
with the vinegar intended for acetification. 

Before using the shavings for filling the generators, it is 
necessary to allow them to swell by placing them in water or 
alcoholic liquid. If this were omitted and the shavings in- 
troduced in a dry state, they would rise above the generators 
as soon as moistened, on account of the increase in volume 
by swelling. 

In most factories it is customary simply to pour the shav- 
ings into the generator, but for a uniform distribution of the 
alcoholic fluid it is advisable to proceed with the filling in a 
certain order. First place the shavings in three or four regu- 
lar layers upon the false bottom, then pour them in loosely to 
a height of 8 to 12 inches, and after leveling the surface as 
much as possible pour in again, and continue in this manner 
until the generator is filled. The uppermost portion should 
again consist of three or four regular layers. 

All the generators used in a vinegar factory should be of 
the same size and charged with the same number of shavings, 
which is best effected by filling them with the same quantity 
by weight. The total surface of shavings being thus nearly the 
same in all generators, the latter will work uniformly, i. e., with 
an equal temperature and draught of air; and in the same time 
convert equally large quantities of alcohol into acetic acid. 




THE arrangement of the manufacturing rooms formerly cus- 
tomary even in large factories is by no means a suitable one. 
The generators were generally simply placed in a room adapted 
for the purpose by its size, while the high temperature re- 
quired was sought to be maintained by heating. By con- 
sidering, however, that every considerable variation in the 
temperature causes also a disturbance in the formation of 
vinegar, it will be seen that the object of keeping up an undis- 
turbed working of the factory cannot be attained by such 
primitive means. A suitable arrangement of the room in 
which the vinegar is to be manufactured is, therefore, abso- 
lutely necessary. 

The principal requisites to be observed are : The mainten- 
ance of a uniform temperature in the room and a suitable 
arrangement for ventilation. Further, simple devices for the 
conveyance of the raw materials and the finished product 
must be provided for, and means devised for regaining the 
acetic acid, with the vapors of which the air in the manufac- 
turing room is constantly saturated. 

For the maintenance of a uniform temperature in the work- 
room, which should remain almost constant even in the cold- 
est season of the year and during abrupt changes in the outer 
temperature, the waljs should be of more than ordinary thick- 
ness and the number of windows and doors sufficient only for 
the necessary light and communication, and so arranged that 
no unintentional ventilation can occur. The windows and 
doors should, therefore, be double, and the latter so placed 
that one can be closed without opening the other. The walls 
and ceilings should be plastered and preferably papered with 
heavy packing paper ; asbestus shingles are also highly recom- 
mended for this purpose. 


Asphaltum being impermeable and also indifferent to the 
action of acetic acid, is undoubtedly the best material for the 
floor of the workroom, though it may also be constructed of 
large slabs of sandstone with the joints filled in with asphal- 
tum. Cement floors can only be recommended provided they 
are immediately after their construction coated with silicate of 
soda until they cease to absorb it. In constructing the floor 
care must be had to give it such an inclination that the entire 
surface can be cleansed by a simple jet of water. If the heat- 
ing channel is conducted lengthwise through the workroom, 
gutters for the rinsing water to run off must be arranged on 
both sides. 

The height of the room depends on that of the generators. 

Heating of the Workroom Heating by a stove placed in the 
workroom itself can only be recommended for very small fac- 
tories ; in larger ones a special heating apparatus should always 
be provided. Where stoves are used it is recommended to 
arrange them so that the fuel can be supplied and the ashes 
removed from the outside, i. e., from a room adjoining the 
actual workroom. In attending to the stoves fine particles of 
ashes will unavoidably reach the air, and from the latter they 
may get into the generators, and being soluble in acetic acid 
may injure the vinegar ferment. 

For large factories a heating apparatus similar to the one 
shown in Figs. 17 and 18 can be recommended. The heater, 
provided with the feeding-door H and the air-regulating door 
A, stands in a vault beneath the center of the room to be 
heated. It is surrounded on all sides by the sheet-iron jacket 
M t reaching from the floor of the cellar to the top of the vault. 
In the vault is a circular aperture, 0, for the reception of the 
flues C and Ci. The latter ascending slightly, run along the 
center of the room to be heated. Above they are covered by 
cast-iron plates, P, and by pushing these plates apart or sub- 
stituting a lattice plate for one of them in any part of the flue, 
warm air can be admitted to the room. If the room is to be 
heated without renewing the air, the register in the flue L, 


which communicates by a flat iron pipe with the lower part of 
the jacket, is opened. The furnace being heated, the air in the 
room is sucked in the direction of the arrow through 'the flue 
L, and passing between the jacket and the furnace, ascends 
strongly heated through and penetrates through the open- 
ings in the flue, air being again sucked through L, and so on. 

FIGS. 17, 18. 

If, however, the air in the workroom is to be entirely re- 
newed, the air-flue L is closed and a register (not shown in 
the illustration) in the lower part of the jacket opened. In 
this case the air in the cellar is sucked in, heated and distrib- 
uted through the flues C and Cj. By partially opening this 



FJG. 19. 

register and that in L, a portion of the air can be renewed at 

In order to be able to form a correct idea of the state of the 
temperature prevailing in the room, it is 
advisable to have several ordinary thermom- 
eters and also a maximum and minimum 
thermometer. If the latter shows no greater 
variation than from 4 to 5, the process of 
heating may be considered as satisfactory. 

A very suitable apparatus for controlling 
the temperature in a vinegar factory is an 
electrical thermometer, which is so arranged 
that a bell rings in case the temperature 
rises above or falls below a certain degree. 
By placing two such thermometers in the 
room, the bell of the one indicates the rise 
of the temperature above the limit, and that 
of the other that it has fallen below it. 

Fig. 19 illustrates the principle of a maxi- 
mum electrical thermometer, i. e., one which 
rings a bell when the temperature of the 
room exceeds a certain limit. Into the bulb 
of an ordinary mercury thermometer is 
melted a platinum wire ; another platinum 
wire. is inserted in the tube up to the mark 
indicating the temperature not to be ex- 
ceeded, for instance, 35 C. The ends of 
the platinum wires projecting from the ther- 
mometer are connected by insulated copper 
wires with a galvanic battery consisting of several elements, 
an ordinary door-bell being inserted in one part of the con- 
ductor. If now, in consequence of a continued increase in the 
temperature, the mercury rises to the point of the platinum 
wire at the figure 35, the circuit of the battery is closed at 
the same time by the column of mercury, and the bell rings 
and keeps ringing until the circuit is again opened by the 
mercury falling below 35. 





The minimum electrical thermometer, used for indicating 
the falling of the temperature below a certain degree, is so 
arranged that one platinum wire is melted into the bulb of the 
thermometer and the other in the tube at the point below 
which the temperature is not to fall. As long as the mercury 
remains above this point a battery, which changes a piece of 
iron to an electro-magnet, whose armature opens a second bat- 
tery which is connected with an electric bell, remains closed. 
If the temperature falls below the minimum, the circuit of 
the first battery is opened, and the armature of the electro- 
magnet falling down effects the closing of the second battery 
and sets the bell ringing. 

By placing such thermometers not only in the working 
room but also in every generator, the control of the entire 
process would be immensely facilitated, but at the present 
time these useful and at the same time inexpensive instru- 
ments are but little used in vinegar factories. 

In factories arranged according to the automatic system, the 
alcoholic liquid is contained in vessels placed at such a level 
that their contents can run directly into the generators. The 
alcoholic liquid having to be correspondingly heated, adequate 
provision must be made for heating the space in which the 
reservoirs are placed. In order not to increase the height ot 
the entire room, it is recommended to place these vessels in 
the center and give only to this portion the required height. 
This has the further advantage that the alcoholic liquid can 
be pumped up by the use of a pump with a short rising-pipe, 
and the liquid can be readily conducted from the reservoirs 
to the separate generators by means of pipes. 




THE first experiments in conveying direct air to every gen- 
erator were made in England ; but though this step towards 
improvement in making vinegar must be considered an 
important advance, the English process failed of being ac- 
cepted in practice on account of the inadequacy of the 
apparatus used. 

In the English factories by a special apparatus a current of 
air was sucked from above to below through every generator. 
As shown in Fig. 20, the tall generator is open on top and 
divided into several partitions by false bottoms, upon which the 
shavings, etc., rest. Above each false bottom holes are bored 
in the circumference of the generator. In the bottom of the 
generator is inserted a pipe which is connected with an 
arrangement for sucking in the air, a blower or air-pump 
being used for the purpose. 

As will be seen from the illustration, the suction of air 
through all parts of the generator cannot be uniformly effected 
by the use of this apparatus, the current of air being much more 
checked in the upper portions by the false bottoms and holes 
in the circumference, than in the lower. Hence the effect of 
the air-pump or blower will chiefly assert itself in the lowest 
partition. This drawback might be remedied by leaving out 
the false bottoms and placing no air-holes in the circumference 
of the generator entirely open at the top. By this means the 
air would be forced to pass in a uniform current through the 
entire layer of the filling material. 

That the passage of the current .of air from above to below 
is entirely incorrect, because contrary to all theoretical require- 
ments, can readily be explained: In a generator in full activity, 
oxidation of alcohol must already take place in the uppermost 
portion, and hence a certain quantity of oxygen is withdrawn 



FIG. 20. 

from the air. This process being also continued in the lower 
parts of the generator, a current of air already deprived of a 
portion of its oxygen, and hence less suitable for the further 

formation of acetic acid, would be 
sucked in the same direction which 
the drops of alcohol take. 

The principal reason advanced 
for the use of a current of air from 
above to below is that by these 
means a uniform temperature is 
maintained in all parts of the gen- 
erators, while it rises considerably 
in the upper part of those in which 
the air passes from below to above. 
This rise of temperature is, however, 
agreeable to nature. The air enter- 
ing from below oxidizes the alcohol 
to acetic acid, becoming thereby 
poorer in oxygen and again heated. 
By the higher temperature it ac- 
quires, it is, however, capable of a 
more vigorous chemical activity, so 
that it will induce the process of the 
formation of vinegar, even in the 
uppermost portions of the genera- 
tor. Besides, the warmer current 
of air moving upwards has the fur- 
ther advantage of yielding heat to 
the drops of alcoholic fluid trickling down. With the use of 
generators of moderate height, and with a suitable regulation 
of the draught of air, the maximum temperature will not be 
exceeded, even in the uppermost portions of the generator. 

If no rise of temperature is observed in the lower portions 
of a generator in which the air passes from above to below, it 
only proves that the air has lost too much oxygen to further 
effect a vigorous oxidation of the alcohol. It will be readily 


understood that under these conditions a diminution in the 
loss of substance can, to a certain degree, be effected, but it i& 
doubtful whether the generators are utilized in the manner 
they should be ; besides, the diminution in loss of substance 
cannot be very considerable. Since a high temperature also 
prevails in ventilated generators, the current of air passing 
downward will be loaded with as much vapor of alcohol or of 
acetic acid as it can absorb at this temperature, and, hence, it 
would seem, no diminution in loss by evaporation could be 
effected. To render this possible, the current of air sucked 
from the generator would have to be sufficiently cooled off by 
a suitable arrangement to allow of the greater portion of the 
vapors carried away by the current of air being condensed to 
a fluid. 

Schulze's Ventilating Apparatus. The ventilation of the vine- 
gar generators, according to the previously described method, 
requires the presence of an uninterruptedly acting power for 
working the air-pump, blower, etc. As is well known, a cur- 
rent of air can, however, be also produced by heating the air 
passing through an ascending pipe, by which it becomes 
specifically lighter and ascends, while denser air enters from 
below, etc. Schulze, as will be seen from Fig. 21, has applied 
this method to the ventilation of vinegar generators. 

Schulze's generator differs somewhat from the ordinary con- 
struction, and is arranged as follows : The vat has a height of 
about 8 feet, and a diameter of 2 feet 6 inches. In the upper 
part it is terminated by a false head, fitting air-tight, and is 
further provided with a cover, in the center of which is an 
aperture about 2J inches in diameter, which serves for the 
entrance of air, while another aperture on the side serves for 
pouring in the alcoholic liquid. In the false head are in- 
serted four glass tubes, open at both ends, and about f inch in 
diameter, which afford a passage to the air. The generator is 
filled with pieces of washed and assorted charcoal, so that 
pieces of the size of a nut are placed upon the false bottom, 
and upon this smaller pieces, gradually decreasing in size 



until those on the top are only that of a pea. In the center 
of the bottom is inserted a wooden tube, open at both ends 
and provided on top with a hood to prevent the trickling in 
of vinegar (see Fig. 10). By a suitable intermediate piece, 
this tube is connected with the draught-pipe (see Fig. 21), in 
which the ascension of the air by heating is effected. 

The draught-pipes are of cast-iron, and are about J inch 
thick and about 4 \ feet long, with a clear diameter of 2 inches. 

FIG. 21. 

They are placed, strongly inclined, over the flues of a heating- 
apparatus and covered above by a double course of stone. The 
air in the iron draught-pipes, being heated by the escaping 
gases of combustion, ascends and effects the passage of a cur- 
rent of air from above to below in the generators. For keep- 
ing up a constant ventilation it is claimed to be sufficient to 
heat the furnace only once a day. With this construction it 
is necessary to have as many draught-pipes as there are gener- 
ators. The same effect might, however, also be attained by 
connecting the pipes leading from several generators with a 
draught-pipe of a somewhat greater diameter and length. 


It is not difficult to prove that a uniform ventilation of the 
generators cannot be obtained by the use of this construction. 
As long as the draught-pipes are strongly heated, a very rapid 
current of air will pass through them and the generators con- 
nected with them, which will, however, decrease in the same 
degree as the pipes cool off. Hence, in the first case, a too 
rapid current of air, accompanied by a correspondingly strong 
evaporation of alcohol, would pass through the generators, and 
in the latter, ventilation would be so sluggish that the process 
of the formation of vinegar would not proceed in a normal 

Generators with Constant Ventilation and Condensation. The 
object to be attained by the use of special ventilating contriv- 
ances is a double one : To conduct a constant current of air 
through the generators, and, further, not to allow the tem- 
perature to rise above a certain limit, so as to decrease by 
these means the loss by evaporation of alcohol and acetic acid. 
This object can, however, be attained only by the use of an 
apparatus which allows of the most accurate regulation of the 
current of air passing through the generator, and is connected 
with a contrivance by which the vapors of alcohol and acetic 
acid carried along by the current of air can be condensed as 
much as possible. The apparatus described below is well 
adapted for the purpose. Its principal parts consist of the 
generator, the apparatus for condensing the vapors, and the 

The construction of the lower part of the generator, Fig. 22, 
is the same as of those previously described. The cover fits 
tightly upon the upper edge of the vat, the joint being made 
air-tight by strips of paper pasted over it. In the center of 
the cover is a square aperture, from which rises a quadrang- 
ular pyramid, P, constructed of boards, upon which sits a low 
prism, A. The sparger D has its center of motion upon the 
strip L, placed in the uppermost portion of the generator, and 
is guided above in the short strip L v which carries the sharp- 
edged ring described on page 51. E is the glass tube through 



which the alcoholic liquid flows into the funnel of the sparger. 
On the point where the pyramid passes into the prism A, is a 
bottom provided with a circular aperture, 0, 2J to 3 inches in 
diameter. Upon the top of the prism A is placed a nut, in 
which runs a wooden screw, provided on the lower end with 
a wooden disk, S, of a somewhat greater diameter than the 
aperture 0. By raising or lowering this screw, the aperture 
can be closed more or less or entirely, and thus the strength 
of the current of air regulated at will in every generator. The 
prisms A of all the generators are connected with each other 
by the conduit R, constructed of boards. 

FIG. 22. 

FIG. 23. 

This conduit R is connected best in the center between 
an equally large number of generators with the condensing 
apparatus, the chief feature of which is a worm similar to 
that used in a still. Fig. 24 shows the apparatus in cross- 

In a sheet-iron vessel of the same height as the generator is 
placed another vessel, so that there is a distance of about 5} 
inches between the walls. From a reservoir situated at a 
higher level cold water runs into the apparatus through the 
pipe K, and off through the short pipe W. In the space be- 
tween the walls of the two vessels lies a tin coil with very thin 


walls and a diameter of at least 2J inches. On top this tin 
coil is connected with the wooden tube R (Fig. 23) and below 
with the iron pipe R, which leads to the ventilating appa- 
ratus. C is a glass tube about 16 inches long and J to f inch 

FIG. 24. 

in diameter, which reaches nearly to the bottom of the flask 
half filled with water. 

The ventilating apparatus consists of an ordinary self-feeding 
stove, but its jacket is closed below so that air can only pass in 
between the heating cylinder and the jacket through the pipe 
R l coming from the condensing apparatus. 

The apparatus works as follows : According as combustion 
in the stove proceeds slowly or quickly by the corresponding 
position of the regulating register, the air between the heating 


cylinder and the jacket becomes less or more heated and as- 
cends with corresponding velocity. But as the further entrance 
of air can take place only through the pipe R ly the tin coil, and 
the wooden tube R, a uniform current of air from below to 
above must pass through all the generators. To regulate the 
strength of the current for each generator, it is only necessary 
to close the aperture (Fig. 22) more or less by raising or 
lowering the screw. 

The current of air passing from the wooden tube R into the 
tin coil carries with it the total amount of evaporated alcohol 
or acetic acid. By passing through the tin coil, which is cooled 
by the water, the air itself becomes cooled off, and the greater 
portion of the vapors held by it condense to liquid and run off 
through the tube C into the bottle. The fluid thus obtained 
consists chiefly of alcohol, water, and acetic acid, and is again 
used for the preparation of alcoholic liquid. On account of the 
peculiar form of the cooling vessel but little water is required 
for feeding it. As the quantity of vapor separated from the air 
will, however, be the greater the more energetically the tin coil 
is cooled off, it is recommended to reduce the temperature of 
the water to nearly 32 F. by throwing in pieces of ice. 

It has been proposed to regain the vapors by conducting the 
air containing them into a large vessel in which water in the 
form of a fine spray trickles down or is injected. It is, of 
course, possible in this manner to condense the greater portion 
of vapors of a higher temperature and tension, but with vapors 
of at the utmost 95 F. little success would be attained. The 
greater portion of the vapors remaining uncondensed, a very 
large quantity of fluid containing but little alcohol would be 
obtained in the course of a day, and this fluid could at the best 
be used only instead of water for the preparation of alcoholic 
liquid. The value of the material thus regained would not 
cover the working expenses of the apparatus. By working, 
however, with the condensing apparatus described above, the 
condensed alcohol does not even contain the total quantity of 
water evaporated with it, and it need only be compounded 


with the corresponding quantity of water and vinegar again 
to yield alcoholic liquid. 

The generator manufactured by Singer, of Berlin, shows an 
essential difference in construction from those previously de- 
scribed. It consists of several shallow wooden vessels arranged 
one above the other and connected with each other by wooden 

FIG. 25. 

tubes so that the alcoholic fluid runs drop by drop from one 
vessel into the other, passing thereby through the tubes. In 
order to distribute the fluid as much as possible, the tubes are 
inside provided with horizontal gutters, whereby the surface of 
the fluid passing through is greatly increased. In addition, 



FIG. 26. 

each of the tubes is provided in the center with a slit running 
length-wise, allowing of a free passage of the air. The latter 
encounters in the tubes the finely-divided fluid and effects the 
oxidation of the alcohol to vinegar. This is repeated four 
times and oftener before the alcoholic fluid has passed through 
the apparatus, whereby, it is claimed, a very complete forma- 
tion of vinegar is attained. The entire apparatus stands in a 
case which protects it from cooling off and from too great an 
access of air, and which can be heated in winter. 

Fig. 25 shows Singer's generator in cross section, and Fig. 
26 the separate vessels and their connection by drip tubes. 
Fig. 25 represents five shallow vats standing one above the 

other, at uniform distances, the 
latter being effected by elongated 

In the bottoms of the vats A 
and A 1 are inserted 37 tubes, a, b, 
by which they are connected with 
the vats B and B 1 below. The 
bottoms of the latter are provided 
only with 32 tubes, which above 
connect the vat B with A 1 and 
below pass into the vat C. 

As will be seen from Fig. 26, 
the sections of the tubes through 
which the alcoholic fluid is to run 
slowly are provided above with 
six annular gutters. Above these 
gutters are four apertures for the 

entrance of the alcoholic fluid. In the center the tubes are 
slit lengthwise for the free admission of air. The lower end of 
each tube is also provided with two gutters. On top each tube 
is closed with a lid, but the end entering the vat below is open. 
Of all the five vats only the upper one, A, is provided with 
a cover, and upon the latter is fixed a holder, /, for securing 
the tube g. Above, the latter is connected with the reservoir 


E, filled with alcoholic fluid and below ends in the short pipe 
h, which permits the alcoholic fluid to run into the upper vat 
A. In addition to the drip-tubes, every two vats standing one 
above the other are connected with a knee. , The upper one 
of these knees i issues from the bottom of the vat A and enters 
the vat B close to the bottom. The second tube connects in 
the same manner, B with J. 1 , the third, A 1 with B 1 , and 
lowest one, B 1 with C. Each of these tubes is provided with 
a cock to allow of the separate vats being connected or discon- 
nected at will. The lowest vat, (7, is provided with two dis- 
charge pipes, one, i, at the bottom, and the other, k, about 1J 
inches higher up. 

The five vats rest upon the reservoir, D, which serves for 
the reception of the total quantity of alcoholic liquid which 
has passed through the apparatus. It is provided with the 
opening, #, which is connected by a rubber tube with the 
cock, J, on C. In addition, D, is provided with a glass gauge, 
PJ which by turning it downward, serves for discharging the 
fluid from D. 

The case enclosing the apparatus is constructed of wood and 
glass, the rubber tube, g, passing through the roof of the reser- 
voir E, holding the alcoholic fluid. On top the roof is pro- 
vided with a trap, m, which can be opened and closed at will 
by means of a rope. Below the case is provided with slides 
n n. By opening the slides and the trap, the admission of air 
can be regulated. 

In the commencement of the operation the cock on E is 
opened and the alcoholic fluid is allowed to run through the 
tube g, and the short pipe h, until it stands 1 J to 2J inches 
deep over the drip-tubes. The cock on the pipe i is then 
closed. The alcoholic fluid now penetrates into the drip-tubes, 
and runs through them into B, which is soon filled so far that 
the openings of the drip-tubes are reached by the level of 
the fluid. As the admission of alcoholic fluid continues un- 
interruptedly, one vat after another is filled, and the alcoholic 
fluid is in the separate drip tubes distributed over a compara- 


tively very large surface, being at the same time brought in 
intimate contact with fresh air. 

The admission of alcoholic fluid can readily be regulated, 
so that on reaching the lowest vat it is converted into vinegar. 

When the apparatus is once in operation, the formation of 
vinegar progresses without interruption, it being only neces- 
sary regularly to fill the reservoir with fresh alcoholic fluid, 
and to draw off the finished vinegar into barrels. If for some 
reason the operation is to be interrupted, the alcoholic fluid 
still contained in the vats is drawn off through the respective 
knees, and the apparatus is filled with water to prevent dry- 
ing out. When manufacture is to be recommenced, the water 
is drawn off, and alcoholic fluid admitted. 

It is doubtful whether this apparatus possesses advantages 
over the ordinary generator, since the surface over which 
the alcoholic fluid is distributed is much smaller than in gen- 
erators filled with shavings. 

Michaelis' revolving generator consists essentially of a strong 
barrel, 3 feet 3 inches in diameter at the widest point, and a 
space of 3 feet 3 inches between the two bottoms. The barrel 
rests horizontally upon two supports, so that it can be rolled to 
and fro upon them. The interior of the barrel is divided by a 
horizontal lath-grating into two partitions, .the upper smaller 
one being filled with shavings. Below the lath-grating in the 
bottom of the barrel is a horizontal tube for the admission of 
air, and above in the side of the barrel a cock for its escape. 
The alcoholic fluid is poured in close to the lath-grating by 
means of a funnel, the air-cock is closed and the barrel re- 
volved to allow of the shavings to become thoroughly saturated 
with the alcoholic liquid. In about 15 minutes the barrel is 
brought back to its original position, and the air-cock opened. 
The commencement of the formation of vinegar will soon be 
recognized by the increase of temperature in the shavings, 
and the operation is then in full progress. 

For the constant continuation of the formation of vinegar, it 
is only necessary to revolve the barrel for a few moments sev- 


eral times a day to saturate the shavings with the alcoholic 
fluid. The progress of the formation of vinegar is shown by 
a thermometer placed in the bottom of the upper space, the 
lowering of the temperature indicating the completion of the 

The apparatus is cleaned by rinsing the shavings, without 
taking them from the barrel, with hot water, and filling the 
barrel with strong vinegar, which is drawn off in 24 hours. 

The advantages of this generator consist, according to the 
inventor, in cheapness of first cost, simple operation, larger 
yield, saving of alcohol, and better quality of the product. 



THE principal work to be performed in a vinegar factory 
consists in pouring at stated intervals the alcoholic fluid into 
the generators. In a large factory several workmen are con- 
stantly engaged in this work, and losses by spilling are un- 
avoidable. Further, it is almost next to impossible always to 
pour in the same quantity at exactly the same intervals, and 
sometimes a generator may even be entirely overlooked, and 
thus remain inactive until the next supply of alcoholic liquid 
is poured in. 

The greatest disadvantage is, however, the interruption for 
several hours daily, of the formation of vinegar in all the gen- 
erators, so that, for instance, in a factory working 16 hours a 
day, one-third of the time is lost. Independently of the small 
return on the capital invested, these interruptions are accom- 
panied by many other conditions injurious to the regular run- 
ning of the factory. 

The greatest of these evils is that with the cessation of the 
supply of alcoholic fluid the propagation of the vinegar fer- 


ment diminishes and finally ceases altogether. Further, the 
development of heat in the interior of the apparatus at the 
same time ceases and the temperature is reduced several de- 
grees, this phenomenon appearing even in factories provided 
with the best heating apparatus and keeping up a constant 
temperature in the workroom during the night. 

In the morning when work is resumed, it is in most cases 
necessary to vigorously air the apparatus by opening all the 
draught holes, in order to gradually restore the temperature 
to the required degree, and it will be some time before the 
apparatus again works in a normal manner. 

The vinegar ferment, however, is very sensitive to changes 
of temperature, as well as to the concentration of the nourish- 
ing substances surrounding it, and there can be no doubt that 
its propagation is prejudiced by the continuous variations of 
temperature to which it is exposed during the interruptions of 
several hours a day. That such is actually the case is shown 
by the fact that the quantity of vinegar ferment formed in the 
generators is small as compared with that which, under con- 
ditions favorable to the ferment, forms in a short time upon 
alcoholic liquids. 

Besides the debilitation of the vinegar ferment and the con- 
sequent disturbance in the regular working of the factory, the 
repeated reduction of the temperature in the generators has the 
further disadvantage that, besides the vinegar ferment, other fer- 
ments for whose development a low temperature is more favor- 
able may be formed, and these ferments may increase to such 
an extent as to entirely suppress the vinegar ferment. There 
can scarcely be a doubt that the many apparently inexplicable 
disturbances in the working of the generators, such as their 
remaining cool notwithstanding an increased current of air, 
the vinegar becoming suddenly weaker, or the entire cessation 
of its formation, find their easy explanation in the daily 
interruptions lasting for hours in the regular working of the 

Besides the increase in the capacity of the factory, disturb- 


ances are, therefore, less likely to occur where the work is 
carried on uninterruptedly, but in order to do this there must 
also be a corresponding increase in the number of workmen 
employed in pouring alcoholic liquid into the generators. 

By the use of simple automatic contrivances for the regular 
pouring out of the alcoholic liquid, the number of workmen 
employed in a vinegar factory can, however, be reduced to the 
attendance required for looking after the heating apparatus, 
raising the alcoholic liquid to a certain height, and an occa- 
sional control of the temperature in the interior of the genera- 
tors. A factor}^ thus arranged requires but little attendance, 
as when once in good working order it may be left to itself for 
many hours without the occurrence of any disturbance. 

According to the characteristics which distinguish the differ- 
ent constructions of continuously working apparatus from each 
other, they may be divided into two principal systems, viz., 
into those with an uninterrupted, and those with a periodical, 
pouring out of the alcoholic liquid, but in either case the latter 
has to be brought into a reservoir placed at a certain height 
above the generators. 


The Terrace System. The alcoholic liquid, as is well known, 
cannot be converted into finished vinegar by passing once 
through the generator, a repeated pouring into several, gen- 
erally three, different generators being required. To avoid 
the necessity of raising the alcoholic liquid three times, three 
rows of generators have been arranged one above another, so 
that" the alcoholic liquid coming from a reservoir placed at a 
higher level flows first into the uppermost generator, and pass- 
ing through this, runs directly into the second, and from 
there into the third, which it leaves as finished vinegar. Fig. 
27 shows a vinegar factory arranged according to this system, 
/. II, III, representing the three rows of generators placed one 
above another, V 1 the reservoir for the alcoholic liquid, P the 
arrangement for pumping the alcoholic liquid into the reser- 



voir, V the distributing vessel for the alcoholic liquid, 8 the 
collecting vessel for the finished vinegar, .fiTthe heating appa- 
ratus for the entire establishment. 

For a uniform supply of alcoholic liquid to the generators 

FIG. 27. 

standing on the same level a conduit, L, from which the alco- 
holic liquid flows into each generator, runs above the upper- 
most row. Another conduit, L l , common to all the genera- 
tors, serves for the reception of fluid (finished vinegar) running 
off from the lowest row, and conducts it to the collecting ves- 


sel, S. The arrows indicate the course the alcoholic liquid 
has to traverse. 

From all appearances the arrangement of a factory according 
to the above-described system would be most advisable, there 
being actually nothing to do but to raise the alcoholic liquid 
once and to remove the finished vinegar from the collecting 
vessel. In practice, however, this so-called terrace system pre- 
sents many difficulties not easily overcome, the greatest un- 
doubtedly being the solution of the heating problem. Experi- 
ence shows that the temperature in a generator must be the 
higher the more acetic acid the alcoholic liquid contains. 
According to this, the highest temperature should prevail in 
the lowest series of generators (///, Fig. 27) and the lowest in 
the uppermost (/). 

But in practice just the reverse is the case even with the 
use of the best heating apparatus, the highest temperature 
prevailing in I and the lowest in III, as, according to natural 
law, the warm air being specifically lighter than the cold 
constantly strives to ascend. 

To overcome this drawback nothing can be done but to place 
the series J, // and III of the generators in as many different 
stories entirely separated from each other, or, in case there is a 
central heating apparatus in the cellar, to correctly distribute 
the warm air in the separate stories by suitably arranged reg- 
isters. The solution of this problem offers no insuperable 
difficulties, but requires the arrangement of the entire factory 
to be carefully planned in accordance with the laws of physics. 

An unavoidable drawback of the terrace system is the cost- 
liness of the factory building, and, finally, that a disturbance 
occurring in one of the generators must simultaneously affect 
two others of the vertical series, which must necessarily remain 
idle until the disturbance is removed. Considering all the 
disadvantages connected with the terrace system, though it is 
seemingly so suitable, it is but little adapted to practice, it 
being much preferable to place all the generators on the same 
level and to divide them into three groups, each of which is 


provided with a reservoir for the alcoholic liquid and a col- 
lecting vessel. 

The mode of working according to this system is as follows : 
The alcoholic liquid is pumped into a reservoir, from which it 
passes through group / of generators and collects in a vessel. 
From the latter it is pumped into a second reservoir placed on 
the same level with the first, and runs through group II of 
generators into another collecting vessel ; from there it is again 
pumped into a third reservoir, and after passing through group 
/// of generators finally collects as finished vinegar in a third 
collecting vessel. 

Though the arrangement of all the generators on the same 
level renders it necessary to raise the alcoholic liquid three 
times, it would seem more suitable than the terrace system for 
the following reasons: 1. By a suitable regulation of the heat- 
ing apparatus the required temperature can be readily main- 
tained in the separate groups of generators. 2. In case of a 
disturbance in one of the groups, the generator in question can 
be left out without causing an interruption in the work of the 
other groups. 3. The power required to pump the alcoholic 
liquid three times into the reservoirs V l , V 2 , and F 3 , is not 
much greater than that which has to be used to raise it to the 
height of the reservoir in factories arranged according to the 
terrace system. 4. Notwithstanding the greater area required, 
the erection of a one-story factory is less expensive than that 
of a three-story building with complicated heating apparatus 
and very strong, solid floors, which are required on account of 
the great weight of the generators. 

The uniform distribution of the alcoholic liquid into each 
generator is very simple in factories arranged according to the 
terrace system, and can be effected in the following manner : 

The false heads are fitted water-tight in the generators ; 
they are provided either with narrow holes alone, or with aper- 
tures loosely filled with cotton-wick, pack-thread, etc. The 
pipes ascending from the vinegar-forming space, which is filled 
with shavings, are inserted water-tight in the false bottoms. 


On the reservoir containing the alcoholic liquid is a spigot 
which can be accurately adjusted, and is securely connected 
with the conduit leading to the separate generators. At the 
place on the conduit where the alcoholic liquid is to be intro- 
duced into the generator is a discharge-pipe also provided with 
a spigot. 

When the factory is to be put in operation the reservoir is 
first filled with alcoholic liquid, the spigots on the several gen- 
erators being entirely open, but the principal spigot closed. 
Now, by suddenly opening the latter, the air in the conduit i& 
expelled by the alcoholic liquid flowing in, and the latter 
rushes in a full stream from the spigots connecting the conduit 
with the generators. These spigots are then closed so far that 
only the quantity of alcoholic liquid required for the regular 
process of the formation of vinegar can enter the generators. 
To prevent the force of pressure from varying too much in the 
conduit by the lowering of the level of the fluid in tire reser- 
voir, it is recommended to give the latter only a slight height 
but a large bottom surface. 

From the lower portion of the uppermost series of genera- 
tors the alcoholic fluid then gradually reaches through a pipe 
the false bottoms of the next series, and from this the lowest 
series, from which it runs off as finished vinegar into the col- 
lecting vessel. 

It will readily be seen that some time for experimenting is 
required before a factory arranged according to this system 
can be brought into regular working order, it being necessary 
to test the fluids running off from the different groups of gen- 
erators as to their contents of acetic acid in order to find out 
whether too much or too little or just enough alcoholic liquid 
reaches the generator, so that the liquid running off from the 
lowest series contains no alcohol and may be considered a& 
finished vinegar. Any fault in the working of the generators 
can in this case be overcome by a corresponding adjustment 
of the spigots so as to regulate the influx of alcoholic liquid. 

Theoretically no more simple or convenient process for 


making vinegar than the terrace system could be devised. 
Provided the spigots supplying the separate generators be once 
correctly adjusted and the temperature of the different stories 
suitably regulated, it is only necessary constantly to supply 
the reservoir with alcoholic liquid, and the heating apparatus 
with fuel, in order to carry on the work for any length of 
time desired. The disadvantages connected with this system 
having been already explained need not be further referred to. 

Lcnze's chamber generator : * This apparatus is a Schuetzen- 
bach generator of logically improved construction, and not, as 
might be supposed at the first glance, an arbitrary modifica- 
tion of the exterior shape. Its construction is based upon the 
following principles : 

1. Saving of space and volume. 2. Simplification of the 
work and facility of control. 3. Utilization to the best ad- 
vantage of the square fermentation-surface. 4. The process is 
carried on without being separated by partitions in many iso- 
lated narrow columns of shavings. 5. Surface-fermentation 
with little height. 6. Large producing capacity. 

The average height of the apparatus is about 7 feet. It is 
rectangular in form, is built entirely of wood, no hoops what- 
ever being used, and is of solid and massive construction. It 
is made in three sizes. Fig. 28 shows a No. 3 apparatus with 
a base of about 107 square feet, length 10 feet, width 6 feet, 
and a capacity of producing 20 to 25 quarts of 13 per cent, 
vinegar per 10J square feet of shavings-surface (base of gen- 

The alcoholic liquid is periodically supplied at fixed inter- 
vals, but the operation may also be carried on continuously 
day and night. 

The attendance of the apparatus is entirely mechanical, by 
means of a pump operated by hand or power. Losses of 
material by spilling or otherwise are impossible since the 
alcoholic liquid moves in closed tin pipes and the finished 
vinegar is conveyed in the same manner. 

*.J. Lenze, Iserlohn, Westfalen, Germany. 



The apparatus is furnished with a lath-bottom and a per- 
forated head, the intermediate space being packed with beech 
shavings. The air-holes are between the actual bottom and 
the lath-bottom and the air-outlets below the perforated head. 
The alcoholic liquid is very uniformly distributed over the 
entire large surface of shavings by the perforated head. The 
latter is tightly covered with cloth, divided into square fields, 

FIG. 28. 

and so secured that it cannot warp or get out of position. 
Notwithstanding its large superficial area the perforated head 
is the coolest place in the apparatus and this evidently con- 
tributes towards reducing the loss by evaporation to a mini- 
mum, and such loss can be still further limited by the use of 
a cover fitting almost air-tight. The upper layer of shavings 
is also not impaired by higher degrees of heat, because the as- 
cending air which has been heated and exhausted, is con- 


stantly cooled by the pourings of alcoholic liquid and partly 
condenses on the lower surface of the perforated head, and 
thus cooled, escapes through a pipe-system below the perforated 

The mode of operating such an apparatus and its attend- 
ance is illustrated by Fig. 28. 

The alcoholic liquid is contained in the vat C and a suffi- 
cient quantity of it is by means of the pump P conveyed to 
the vat A, where it is diluted to a weak wash. When the 
operation is carried on with back pourings, the vat B contains 
the vinegar; otherwise it is omitted. The intermediate vat 
E effects automatically by suitable contrivances the measuring 
off of the separate pourings, so that after pumping the entire 
quantity of alcoholic liquid required for one day, the actual 
labor is finished, which requires about one hour's consump- 
tion of time and power, no matter whether one or several ap- 
paratuses are operated, larger pumps being used in the latter 

For the accurate control of the operation a contrivance is 
provided which indicates in the office whether and at what 
time the separate pourings have been effected. 

The product running off from the apparatus collects in the 
course of the day in the vat D. When the latter is full, the 
overflow passes through a pipe to the storage-vat. By this 
arrangement the danger of any of the vats running over is 

Plate Generator. This generator, patented by Dr. Bersch, of 
Vienna, Austria, is so arranged as to render the formation of 
aldehyde as well as the destruction of acetic acid already 
formed impossible, and the loss by evaporation is reduced to 
a minimum. As will be seen from the description, the 
arrangement of the apparatus is such that on all portions of 
the surface of the plates air and alcoholic liquid are in undis- 
turbed contact. Hence the formation of vinegar takes place 
constantly and the regulation of the current of air can be 
effected with the utmost accuracv. Since the effective surface 


of each apparatus, i. e., the surface upon which the formation 
of vinegar actually takes place, is more than 10,764 square 
feet, the performance of this generator is extremely large, sur- 
passing by far that of a generator packed with shavings. 

This generator is provided with a contrivance which auto- 
matically attends to the pouring-in of alcoholic fluid with the 
regularity of clock-work, and thus the work of a factory using 
a large number of generators can be done by a single work- 
man, he having nothing else to do than to fill once a day the 
reservoir for alcoholic fluid. 

In its most recent construction the plate-generator consists 
of a vat filled inside with layers of extremely thin plates of 
wood arranged in such a manner that the separate layers are 
fixed crosswise at right angles one above the other. Since 
every two plates in the layers lying alongside each other are 
kept apart by prismatic wooden rods, fluid can run down on 
both sides of the plates, and air ascend undisturbed between 

Since the total surface of 'the wooden plates in a generator 
about 8J feet high is more than 10764 square feet, and for- 
mation of vinegar takes place uninterruptedly upon this 
entire surface, the efficacy of the plate generator as regards 
producing capacity is the highest attainable. 

Through a pipe, open at both ends, in the bottom of the 
generator, air is admitted to the interior. The upper portion 
of this pipe is furnished with a hood to prevent fluid from 
dropping into it, and the lower opening is covered with fine 
gauze to exclude the entrance of vinegar lice (vinegar mites). 

The strength of the current of air in the generator is regu- 
lated by a register-bar in the cover of the apparatus, in which 
is also fixed a thermometer. In the commencement of the 
operation the register-bar is so set that the thermometer indi- 
cates the temperature about 91 to 93 F. suitable for the 
formation of vinegar. So long as alcoholic liquid runs in 
and the temperature of the workroom remains the same, the 
same temperature will be indicated by the thermometer, be- 



cause in equal periods of time the same quantity of vinegar 
will always be formed and a quantity of heat corresponding 
to it developed. 

The uniform distribution of the alcoholic fluid in the form 
of very fine drops over the plates in the interior of the gen- 
erator is effected by a sparger fixed over the uppermost layer 
of plates. 

The apparatus, like every other generator, can be charged 
by pouring in the alcoholic liquid by hand. However, to 
make it entirely independent of the workman, and especially 

to keep it working regularly day and night without interrup- 
tion, it is provided with an automatic pouring contrivance. 
This contrivance consists of a vat of such a size as to be capa- 
ble of holding the fluid required for supplying for 24 hours 
one generator or a group of two, three, four or more genera- 
tors. In this supply-vat floats in a suitable guide a wooden 
float-gauge,|which rises and sinks with the level of the fluid. 
To this float-gauge is secured a siphon, the longer leg of which 
is furnished with ^a [checking contrivance which has to be 



accurately regulated. By shifting this checking contrivance, 
the quantity of fluid discharged in a certain unit of time, for 
instance, in one hour, can be determined. Since the siphon 
sinks with the level of the fluid, and its length remains un- 
changed, the fluid always runs off under the same pressure. 

The liquid running from the siphon passes into a distribut- 
ing vessel underneath. The latter should be of sufficient 
capacity to hold the total quantity of liquid required for one 

FIG. 30. 

pouring upon all the generators in a battery. If, for instance, 
every generator in a battery of twenty-four is to receive a 
pouring of 3 quarts, the distributing vessel should have a 
capacity of at least 3 X 24 = 72 quarts. The automatic pour- 
ing contrivance is fixed in the distributing vessel. When the 
latter contains the quantity of alcoholic liquid required for 
one pouring for a determined number of generators, the time 
fixed between every two pourings has elapsed. The auto- 
matic pouring contrivance then opens the distributing vessel 
and the alcoholic liquid passes through the conduits to the 


generators. When the distributing vessel has been emptied, 
the discharge-contrivance closes automatically, the distribut- 
ing vessel is filled within the determined time, and is again 
emptied when this time has elapsed. The automatic distribut- 
ing contrivance thus continues working without interruption 
so long as liquid is contained in the supply-vat. If the latter 
is of sufficient capacity to hold enough alcoholic liquid for 24 
hours, it is only necessary to fill it in the morning. 

Figs. 29 and 30 show the arrangement of the separate parts 
of a plant for automatically working plate generators. Fig. 
29 is a view from above and Fig. 30 a side view. V is the 
supply-vat for the alcoholic liquid, S the float-gauge to which 
is secured the siphon H. A is the automatic. distributor, and 
J the conduits conveying the alcoholic liquid to the separate 
plate-generators P. The dotted line aa represents the level of 
the fluid in the supply-vat. 


The Three-group System. In the second system of automatic 
generators it has been sought to imitate the ordinary working 
of a vinegar factory by providing the apparatus with certain 
mechanical appliances which allow of the distribution at cer- 
tain stated intervals of any desired quantity of alcoholic liquid 
into the generators. The term " periodical " may be applied 
to this system of automatic apparatus. 

The mechanical appliances used for the purpose of admitting 
at certain intervals a fixed quantity of alcoholic fluid into the 
generator may be constructed in various ways, the tilting 
trough, shown in Figs. 12 and 13, p. 49, being an example. 
By a modification of the apparatus, as shown in Fig. 31, any 
desired quantity of fluid can with its assistance be at certain 
intervals admitted to the generator. The fluid may be either 
poured out upon the false head, or, what is more suitable 
for its better distribution, used for feeding a sparger. 

As seen from the illustration a prismatic box with a bottom 
formed of two slightly inclined planes, stands at a suitable 



height over each generator. In this box a tilting trough is 
placed so that its axis of revolution runs parallel with the line 
formed by the two bottom surfaces of the box. On the point 
of contact of the two, a pipe is inserted which extends to the 
false head or to the funnel of the sparger. Above the box is 
a spigot connected by a pipe with a reservoir for the alcoholic 

FIG. 31. 

fluid placed at a higher level. This reservoir serves for sup- 
plying a large number of generators, and can be shut off by a 
carefully adjusted spigot. From the latter a vertical pipe 
leads to the conduit running in a horizontal direction over the 
generators. The pipe is provided with small spigots which 
discharge the fluid into the tilting troughs. 



By giving each tilting trough such a capacity that, for in- 
stance, each partition holds 5 quarts, and adjusting the spigot 
so that 30 minutes are required for filling one partition, the 
trough will, at the expiration of this time, tilt over and empty 
the fluid upon the inclined planes. From here it runs into 
the sparger, and setting the latter in motion is poured in the 
form of a fine spray over the shavings. Since the other parti- 
tion of the tilting trough has the same capacity, as the first, 
and the quantity of the alcoholic fluid remains the same, the 

FIG. 32. 

trough will, after the expiration of 30 minutes, again tilt over, 
and again empty 5 quarts of fluid, this being continued as 
long as the reservoir contains any fluid. 

In place of the tilting trough the so-called " siphon-barrel," 
Fig. 32, may be used for effecting the discharge of a certain 
quantity of fluid at a stated interval. In a spherical vessel 
placed at a higher level than the edge of the funnel of the 
sparger is a siphon, the longer leg of which passes through the 
bottom of the vessel into the funnel. On the edge of the vessel 



Fro. 88. 

is a spigot which is connected with the pipe conveying the 
fluid, and so adjusted that within a previously determined space 
of time the vessel is filled with fluid up to the height indicated 
by the dotted line. As soon as the fluid reaches that height, 
action of the siphon commences, and the content of the vessel 
runs through the longer leg into the funnel of the sparger until 
its level is sunk to the edge of the shorter leg. The action of 
the siphon then ceases until the vessel is again filled up to the 
line, when it recommences, and so on. 

The siphon of bent glass tubes being very liable to breakage, 
it is frequently replaced by the so-called bell-siphon, the ar- 
rangement of which is shown in Fig. 33. It consists of a glass 
tube which forms the longer leg of 
the siphon, while a glass cylinder 
secured to this tube by means of a 
perforated cork, represents the other 
leg. The action of this siphon is 
the same as the other. 

In working with automatic appa- 
ratus, fixed quantities of fluid being 
at stated intervals introduced, pro- 
vision for the reception of the fluid 
must be made in the apparatus itself, 
or for its being conducted to a spe- 
cial reservoir at the rate at which it 
trickles from the shavings. In the 
first case the space beneath the false 
bottom must be of sufficient size to 

receive the fluid passed through the apparatus in a certain 
time. This time being suitably fixed for 12 hours, the appa- 
ratus can during this time work without further attendance, 
so that the required space beneath the false bottom can be 
calculated by multiplying the number of pourings with the 
quantity of fluid poured in at one time. 

Example : The generator receives at intervals of 30 min- 
utes a pouring of 5 quarts, hence in 12 hours 24 pourings of 


5 quarts each = 120 quarts. The space beneath the perfo- 
rated false bottom must therefore be of sufficient capacity to 
receive up to the height of the draught-holes at least 120 
quarts of fluid. 

As will be seen from the following general description of a 
vinegar factory, arranged according to the automatic principle, 
it is decidedly preferable to arrange the generators so that the 
fluid trickling from . the shavings is at once conducted to a 
collecting vessel. 

Arrangement of a Vinegar Factory Working According to the 
Automatic Principle. As previously stated, it is not possible to 
convert all the alcohol contained in the liquid into acetic acid 
by one pouring ; only a portion of the alcohol being converted, 
and this semi-product is brought into a second generator, and, 
if the liquid used is very rich in alcohol, into a third. In the 
second apparatus another portion of the alcohol is converted 
into acetic acid, and the process finished in the third. 

It being in all cases advisable to prepare vinegar with a 
high percentage of acetic acid, most manufacturers now pass 
the alcoholic liquid successively through three generators. In 
practice it is recommended to place the generators which are 
to receive alcoholic liquid of the same content of acetic acid 
alongside each other, which leads naturally to the division of 
the generators into three groups. If, for instance, a factory 
contains 48 generators, each group contains 16 ; group I is 
charged with freshly prepared alcoholic liquid ; the generators 
of group II contain the alcoholic liquid which has already 
passed through those of group I, and group III is charged 
with the fluid yielded by group II. 

Besides the easy control of the work, this arrangement into 
groups has another advantage. The generators in which the 
last remnants of the alcohol of a quite strong fluid are to be 
converted into acetic acid are best kept at a somewhat higher 
temperature ; and with a suitably arranged heating apparatus 
and the eventual use of curtains by which the workroom can 
be divided at will into two or three partitions, it can be readily 


arranged to convey somewhat more heat to the second group 
of generators and the greatest quantity of it to the third. 

The height of the actual workroom of the factory should not 
be greater than required by that of the generators. The reser- 
voir is placed under the roof of the workroom, while the col- 
lecting vessels are either sunk in the floor or placed in the 

Below is given a description of a periodically working estab- 
lishment with 24 generators. The generators are arranged in 
three groups, I, II, and III, the following articles belonging 
to each group : 

8 generators ; 

1 reservoir; 

1 collecting vessel ; 

8 apparatuses for the distribution of the alcoholic liquid into 
the generators ; 

Conduits for the alcoholic liquid to be poured in ; 

Conduits for the alcoholic liquid running off. 

For the three groups in common : 

A pump to convey the alcoholic liquid from the collecting 
vessels to the reservoirs. 

A flue for the conveyance of warm air from the heating 
apparatus in the cellar and for its distribution in the work- 

An apparatus for heating the alcoholic liquid. 

The three reservoirs rest upon the joists of the ceiling of the 
workroom, each being enclosed by a small chamber con- 
structed of boards which are papered. In the floor of each 
chamber is a man-hole for access to the reservoir. The man- 
holes should not be furnished with doors, it being of import- 
ance that the reservoirs should constantly be surrounded by 
warm air which ascends through the man-holes. To prevent 
loss by evaporation the reservoirs should be provided with 
well-fitting covers. 

To retain solid bodies such as shavings, flakes of mother of 
vinegar, etc., which might eventually obstruct the fine aper- 


tures in the false head or sparger, a filter is placed on the 
end of the pipe through which the alcoholic liquid passes into 
the reservoirs. A suitable filter for the purpose is a horse-hair 
sieve containing a linen bag, the latter being from time to 
time replaced by a new one. 

The conduits for the conveyance of the alcoholic liquid to 
the distributing vessels and from there to the generators are 
best constructed of thick glass tubes, the connection of two 
pieces being effected by pieces of rubber hose pushed over the 
ends and secured with twine. 

Each generator may be furnished with a vessel containing the 
automatic arrangement, it being, however, in this case neces- 
sary to provide for each a special conduit from the reservoir, 
which for a factory containing a large number of generators is 
rather expensive. Hence it is recommended to use for each 
group only one or at the utmost two distributing vessels, and 
from them to extend smaller conduits to the separate -gene- 
rators. Each of the principal conduits is provided, at the place 
where it enters the distributing vessel, with a spigot, which is 
adjusted for the discharge of a certain quantity of alcoholic 
liquid. If, as above mentioned, every generator is to receive 
a pouring of 5 quarts of alcoholic liquid every 30 minutes, the 
distributing vessel serving for a group of 8 generators must 
have a capacity of 40 quarts, and the spigot has to be so 
adjusted that exactly this quantity passes through it in 30 

The discharge-pipe of the automatic arrangement must enter 
a space in which are inserted eight pipes having the same 
diameter, which conduct the alcoholic liquid to the separate 
generators. By this arrangement all the generators receive 
simultaneously a pouring of an equal quantity of fluid which 
either sets the sparger in motion or gradually trickles through 
the apertures in the false head. The alcoholic liquid which 
has passed through the generators collects either in the space 
under the false bottom or runs directly through conduits to 
the collecting vessels. 


The conduits placed before the discharge apertures of the 
generators are intended to conduct the alcoholic liquid to the 
reservoirs, and there being no pressure of fluid in them they 
might be merely open gutters. For the sake of cleanliness and 
to avoid losses by evaporation it is, however, advisable to use 
glass tubes for the purpose. At the places where the dis- 
charge-pipes of the generators are located, the connection of 
two glass tubes is effected by a wooden joint with an aperture 
on top in which is placed a glass funnel. For collecting ves- 
sels for the alcoholic fluid running off from the generators of 
one group, vats provided with lids are used. They have to be 
placed so low that some fall can be given to the conduits, and 
in each of them is a pipe provided with a spigot, which serves 
as a suction-pipe for the pump intended to raise the alcoholic 

The manner of working in a factory thus arranged is as 
follows : * The collecting vessel Ci serves for the preparation 
of the alcoholic liquid, which is then pumped into the reser- 
voir Ri, from whence it runs through the first group of gen- 
erators, Gi, to the collecting vessel, Cn. From this it is 
pumped into Rn, and runs through the second group of gen- 
erators, Gn, into the collecting vessel Cm. On being pumped 
up the third time it runs from the reservoir Rm through the 
third group of generators Gm, and passes as finished vinegar 
either into a fourth collecting vessel or is at once conducted 
into storage barrels. 

The distance the alcoholic liquid has to be raised from the 
bottom of the collecting vessels to the reservoir amounting to 
not more than from 23 to 25 feet, an ordinary suction-pump 
may be used for the purpose, though a forcing pump is better, 
it doing the work more rapidly. The pump must be con- 
structed of material entirely indifferent to acetic acid (wood, 
glass, hard rubber, tin,, or thickly silvered metal). 

*To avoid repetition the collecting vessels are designated : Ci, n, in ; the res- 
ervoirs Ri, iiTand.iii 1 .; the groups of generators Gi, n, in. 



Any metallic vessels used in the factory should be of pure 
tin, i. e., unalloyed with other metals, it being the only metal 
entirely indifferent towards acetic acid, but unfortunately it is 
too soft to be suitable for the construction of pumps. 

The pump is generally located in the immediate neighbor- 
hood of the collecting vessels, and the three branches of its 
suction pipe pass into the latter. When one of the collecting 

FIG. 34. 

vessels is to be emptied, the spigot of the branch pipe entering 
it is opened and the spigots of the other branch pipes are 

Ordinary well or river water being used in the preparation 
of the alcoholic liquid, the temperature of the latter does not 
generally exceed 54 F., and if it were thus introduced into 
the generators acetification would be very sluggish until the 
temperature rises to above 68 F. Independently of the loss 


of time, there would be the further danger of injuring the de- 
velopment of the vinegar ferment ; hence it is necessary to heat 
the alcoholic liquid to the temperature required. This is best 
effected by passing it through a coil surrounded by hot water. 
Fig. 34 shows an apparatus especially adapted for heating the 
alcoholic liquid. In a copper or iron boiler filled with water, 
which can be heated from below, is a coil, S, of pure tin ; it 
enters the boiler above at a and leaves it at 6, so that the place 
of inflow is at the same level with that of outflow. With 
this form of construction the coil of course remains always 
filled with liquid, which with the use of pure tin is, however, 
of no consequence ; besides, this can be remedied by placing 
on the lower coil a narrow pipe, R, which projects above the 
edge of the boiler and is bent like a siphon. By opening the 
spigot h the fluid contained in the coil runs off through R. 

^The rising pipe of the forcing-pump is provided with an 
arrangement by which the alcoholic liquid can be brought 
either directly from the collecting vessel into the reservoirs, or 
first forced through the heating apparatus. It consists of a 
prismatic wooden body provided with three spigots. By clos- 
ing spigots 2 and 3 and opening 1, the alcoholic liquid is 
immediately conveyed from the collecting vessels to the reser- 
voirs. By closing spigot 1 and opening 2 and 3, which are 
connected by short pieces of rubber hose with the ends of the 
coil, S, the alcoholic liquid forced upward from the collecting 
vessels by the pump must pass through the heating coil, and 
after being heated it returns to the rising pipe, which conveys 
it to the reservoirs. The arrows in the illustration indicate 
the course of the alcoholic liquid has to traverse when spigots 
2 and 3 are open and 1 closed. 

The diameter and length of the tin coil depends on the 
quantity of fluid which is to pass through it, though one with 
a clear diameter of 12 to 14 inches and a length of 23 to 26 
feet will, as a rule, suffice. Besides by slower or quicker 
pumping the fluid can be forced with less or greater velocity 
through the coil and correspondingly more or less heated. 


The walls of the coil should be as thin as possible so as to 
yield heat rapidly. 

The heating of the alcoholic liquid, of course, can also be 
effected by heating one portion more strongly than necessary 
and reducing it to the required temperature by mixing with 
cold fluid. In working, however, with a fluid containing living 
vinegar ferment and such, as will be explained later on, is 
claimed to be already contained in freshly prepared alcoholic 
fluid care must be had not to heat the liquid above 120 F., 
this temperature being destructive to the ferment. 



Acetification of the Generators. The object of acetification is 
to thoroughly saturate the filling material shavings, char- 
coal, etc. of the generators with vinegar and to cause the 
development of the vinegar ferment upon it. The generators 
are first filled with the filling material, the false heads or 
the spargers are next placed in position, and the temperature 
of the workroom is brought up close to 86 F. For acetifica- 
tion, i. e., saturating the shavings, vinegar of the same 
strength, i. e., with the same content of acetic acid as that 
which is to be prepared in the generators, is used. For every 
35J cubic feet of the space filled with shavings or charcoal are 
required for complete acetification the following quantities of 
vinegar : 

For shavings loosely poured in 60| to 71 gallons. 

For shavings piled up one alongside the other ..90 to 105 gallons. 
For charcoal, the size of a walnut 142J to 211 \ gallons. 

The value of the vinegar used for acetification has to be 
considered as dead capital. 


The first vinegar running off from the generators is not only 
considerably weaker than that used for acetification, but, not- 
withstanding the previous lixiviation of the wood, has a dis- 
agreeable taste so as to render it unfit for the preparation of 
table vinegar, and can only be utilized, for instance, in the 
preparation of acetate of lead, etc. When the vinegar running 
off exhibits a pure taste, it is collected by itself and later on 
converted into a product of greater strength by mixing it with 
alcohol and passing again through the generators. By this 
saturation of the shavings with vinegar, the vinegar ferment 
locates in abundance upon the surface of the shavings, and 
the generators are fit for the formation of vinegar. 

Regular production, however, can be commenced only grad- 
ually, which may be illustrated by an example as follows : 

At first, for instance, alcoholic liquid is introduced only 
once a day, either early in the morning or in the evening. 
In about eight days, or under certain conditions even later, 
the temperature in the generators has risen to from 86 to 95 
F., and alcoholic liquid may now be introduced twice daily, 
for instance, early in the morning and in the afternoon. The 
fact that the generator is working is recognized by the in- 
creased temperature and by the flame of a candle held near a 
draught-hole being drawn inwards. After eight to fourteen 
days more the thermometer shows 96 to 98 F., and then 
alcoholic liquid is introduced three times daily, for instance, 
early in the morning, in the forenoon and in the afternoon, 
whereby the temperature rises to 102 or 104 F. If now the 
vinegar running off shows the desired strength, the generators 
are in good working order, and are subjected to the regular 

Accelerated Acetification. By closely considering the process 
which must take place in acetification and the first stage of 
the operation, it will be plainly seen that the above-described 
method cannot be called a rational one, there being a waste of 
time as well as of material, and the commencement of regular 
working being largely dependent upon accident. 


The object of Rectification is, as previously stated, first to 
thoroughly saturate the shavings with vinegar and next to 
develop the vinegar ferment upon them. This can, however, 
be attained in a more suitable and a quicker manner than by 
the above process. 

Air-dry wood contains on an average 20 per cent, of water, 
and during acetification this water must be gradually replaced 
by vinegar ; hence the vinegar trickling from the generators 
will remain poor in acetic acid and rich in water until the 
shavings are entirely saturated with pure vinegar and the 
water has been expelled. 

The removal of the water from the shavings and its substitu- 
tion by vinegar are effected by osmose, i. e., the cells of the 
wood surrounded by vinegar yield a fluid consisting of water 
and extractive substances of the wood and absorb sufficient of 
the exterior fluid until both liquids have the same composition. 
Now, by pouring only a small quantity of vinegar at one time 
over the shavings in the generator, as is done in acetification 
according to the old method, the course of the process is very 
slow, 14 days or more, as already mentioned, being required 
before the vinegar running off' shows no longer a change in its 

In a generator in a stage of acetification an uninterrupted, 
though slight, current of air upwards takes place, since even 
with the use of the best heating apparatus the air in the upper 
layers is warmer than in the lower. This current of air be- 
comes stronger with the development of larger quantities of 
vinegar ferment and causes a large absolute loss of vinegar. 
The greater portion of this loss must be set down as being due 
to evaporation, which must be considerable on account of the 
great surface over which the vinegar is distributed, and the 
smaller portion, to consumption by the vinegar ferment. 

By placing the shavings in vinegar the above-described pro- 
cess of substitution of vinegar for the fluid contained in the 
cells of the wood takes place very quickly, and, theoretically, 
it would therefore seem to be advisable to follow the same 


course on a large scale, i. e., to saturate the shavings with 
vinegar before placing them in the generators. By using 
artificially dried shavings (see p. 54) the saturation is effected 
in the course of a few hours, the dry" woody tissue absorbing 
the fluid like a sponge. 

The shavings, while still hot, are brought into a vat and 
covered with the vinegar to be used for acetification. In about 
12 hours they are thoroughly saturated. The excess of vine- 
gar is drawn off through the tap-hole in the bottom of the vat, 
and having absorbed neither water nor extractive substances 
from the steamed and thoroughly dried shavings can be imme- 
diately re-used for the saturation of another portion of shav- 
ings. The saturated shavings are at once used for filling a 
generator, and the latter, which may now be considered as 
completely acetified, can at once be employed for the process 
of the formation of vinegar according to the method described 

Instead of in a vat, the shavings can also be saturated 
directly in the generator. For this purpose the shavings, 
after having been artificially dried, are immediately brought 
into the generator, and vinegar is poured over them either by 
means of the false head or the sparger until a considerable 
quantity has accumulated in the space below the false bottom. 
This accumulation is then drawn off and again poured over 
the shavings, this being continued until they are thoroughly 
saturated, which is effected in a comparatively short time. 

Induction of the Operation with an Artificial Culture of Vinegar 
Ferment. In the process of accelerated acetification of the 
generators no development of vinegar ferment can of course 
take place, since by heating the shavings to about 212 F. 
any fermenting organisms accidentally adhering to them are 
destroyed. The vinegar ferment increases with astonishing 
rapidity provided it finds nutriment suitable for its develop- 
ment. Vinegar is, however, a very poor material for this 
purpose, and this is very likely the reason why weeks are re- 
quired before production can be commenced in generators 


acetified according to the old method. The ferment can y 
however, be so rapidly propagated in the generator that pro- 
duction can be commenced almost immediately after acetifi- 
cation is complete. 

For this purpose a method similar to that employed in the 
manufacture of alcohol and yeast has to be pursued and vigor- 
ous ferment obtained by cultivation. As previously mentioned, 
the ferment causing acetic fermentation is widely distributed 
throughout nature and is most abundantly found in the air of 
thickly populated regions. 

The "pure culture" of the vinegar ferment, i. e., in which 
no other than the desired ferment is developed, is not diffi- 
cult, it being only necessary to prepare a fluid especially 
adapted for its nutriment and allow it to stand at a suitable 
temperature in order to obtain in a few days a vigorous 
growth produced by a few individual germs reaching the fluid 
from the air. The best fluid for the purpose is one which con- 
tains, besides a large quantity of water about 85 to 90 per cent. 
a certain amount of alcohol and acetic acid, and very small 
quantities of nitrogenous substances and mineral salts. Hence 
its preparation is not difficult, it being only necessary to mix 
ordinary vinegar and alcohol in suitable proportions and add a 
small quantity of a fluid containing nitrogenous substances 
and mineral salts, such as wine, cider, beer or malt extract. 
Numerous experiments have shown that a fluid containing 
from 4 to 6 per cent, of acetic acid and the same quantity of 
'alcohol with the addition of a small quantity of one of the 
above-mentioned fluids is best adapted for the vigorous nour- 
ishment of the vinegar ferment. Ordinary table vinegar con- 
tains as a rule from 4 to 6 per cent, of acetic acid ; the average 
percentage of alcohol is in wine from 8 to 10 ; in cider from 
4 to 6 ; and in beer from 3 to 5. Taking this statement as a 
guide, the preparation of a fluid containing from 4 to 6 per 
cent, of acetic acid, 4 to G per cent, of alcohol, and the required 
nitrogenous combinations and salts will not be diflicult. 

Fluids of this composition are obtained by mixing, for in- 


stance, equal parts of cider and vinegar, or one part of wine 
with two of vinegar, or one part of beer with three of vinegar, 
and adding 5 per cent, of 90 per cent, alcohol to the mixture. 
Such mixtures, possessing the power of vigorously nourishing 
the vinegar ferment, can at the same time be considered as 
types for the preparation of alcoholic liquid of suitable com- 

To assure the exclusive development of vinegar ferment 
upon any of the above-mentioned mixtures it is best to heat 
it to the boiling-point of water. Young wine as well as cider 
contains considerable quantities of albuminous substances in 
solution, and fluids of this nature being well adapted for the 
nutriment of the mold ferment, the development of the latter 
might increase to such an extent as entirely to suppress the 
vinegar ferment and thus render its cultivation a failure. 
Beer is also very suitable for the nutriment of the mold fer- 
ment, though in a less degree than young wine, and besides 
living yeast, contains alcoholic ferment. 

By heating wine or beer only for a moment to about 158 
P., a large portion of the albuminous substances in solution 
becomes insoluble, and on cooling separates as a flaky precipi- 
tate, all ferments present in the fluid being at the same time 
destroyed. Hence for the preparation of a fluid especially 
adapted for the cultivation of pure vinegar ferment, it is 
recommended quickly to heat to the boiling point 1 quart of 
ordinary white wine in a covered porcelain vessel, and after 
cooling to the ordinary temperature, to mix it with 2 quarts 
of vinegar. To remove the separated insoluble albuminous 
substances, filter through blotting paper. 

To prepare a nourishing fluid from beer, heat a quart of it 
to the boiling point, mix it after cooling with 3 quarts of 
vinegar, add J quart of 90 per cent, alcohol, and filter. 

Distribute this fluid in a number of shallow porcelain vessels 
and place the latter near a window in the heated workroom. 
To prevent dust from falling into the fluid, cover each dish with 
a glass plate resting upon two small wooden sticks placed 


across the dish. In two or three days, and sometimes in 24 
hours, the commencement of the development of the vinegar 
ferment will be recognized by the stronger odor of vinegar than 
that possessed by the original fluid and by the appearance of 
the surface of the liquid. By observing the latter at a very 
acute angle, dull patches resembling grease-stains and consist- 
ing of a large number of individuals of the vinegar ferment 
will be seen. In a few hours these patches will have increased 
considerably, until finally the entire surface appears covered 
by a very delicate veil-like layer of vinegar ferment. 

By touching the surface with the point of a glass rod a cer- 
tain amount of the coating adheres to it, and by rinsing it off 
in a fluid of similar composition not yet impregnated, the fer- 
ment quickly develops upon it. By placing a drop of the fluid 
under the microscope a picture similar to that shown in Fig. 
2, p. 14, presents itself, the entire field of vision being covered 
with germs of vinegar ferment. 

By the development of mold ferment the cultivation of pure 
vinegar ferment may sometimes result in failure even with the 
use of the above-mentioned fluids. The development of this 
ferment is recognized by the appearance of white dots upon 
the fluid, which quickly increase to white opaque flakes, and if 
left to themselves finally combine to a white skin of a peculiar 
wrinkled appearance. Fig. 35 shows a microscopical picture 
of such abortive culture of vinegar ferment. By observing 
at the commencement of this phenomenon the fluid with the 
microscope, very small individuals of vinegar ferment, 6, will 
be observed alongside of the much larger oval cells a, of the 
mold ferment. Such fluid being not adapted for our purposes 
has to be thrown away and the dish rinsed off with boiling 

When the fluid in the dishes is entirely covered with pure 
vinegar ferment, it is poured into a vessel containing the 
greater portion of the alcoholic fluid intended for the first 
charge of the generators, and in the course of 10 hours the 
entire surface of this fluid is covered with vinegar ferment. 



This fluid being poured into the sufficiently acetified genera- 
tors and trickling gradually through them, the greater portion 
of the ferment adheres to the shavings, and increases with 
such rapidity that the great rise of temperature in the interior 
of the generators shortly indicates the regular beginning of 
their activity, and the pouring in of alcoholic liquid can at 
once be commenced. 

Vinegar ferment developed upon one of the above-mentioned 
fluids is evidently so constituted that it can be thoroughly 

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nourished by it, and hence the generators might be continued 
to be charged with alcoholic liquid of a corresponding com- 
position. It being, however, as a rule, desired to manufacture 
as strong a product as possible, an alcoholic liquid much richer 
in alcohol than the above-mentioned nourishing fluids has to 
be used. 

By, however, suddenly changing the nourishing fluid of the 
vinegar ferment, for instance, from a fluid containing only 4 
to 6 per cent, of alcohol to one with 12 to 13 per cent., the 
action of the ferment would very likely be sluggish before it 


became accustomed to the new conditions. Further, its 
activity might suffer serious disturbance and its propagation 
decrease very sensibly, so that notwithstanding strong heating 
of the workroom and thorough ventilation of the generators, 
the temperature in the latter would suddenly fall, and would 
only be restored to the required degree after the ferment had 
become accustomed to the new conditions and recommenced 
its vigorous propagation. 

To overcome such annoying disturbances, 'it is only neces- 
sary to gradually change the composition of the nourishing 
fluid to that which the alcoholic liquid to be worked in the 
generators is to have. Commencing, for instance, with an alco- 
holic liquid containing 5 per cent, of alcohol, the next day 
one with 6 per cent, is used, the succeeding day one with 7 
per cent., and so on until the maximum percentage of alcohol 
the liquid is to have is reached. 



BY the term " alcoholic liquid" is to be understood every 
kind of fluid to be converted into vinegar which, besides water 
and small quantities of nourishing salts and albuminous sub- 
stance, does not contain over 14 per cent, of alcohol. The 
term " wash " or " mixture " is frequently applied to the alco- 
holic liquid. In the directions generally given for the prepa- 
ration of such liquids, vinegar is mentioned as an indispensa- 
ble constituent. While it cannot be denied that a content of 
vinegar in the alcoholic liquid exerts a favorable effect-upon 
the formation of vinegar, it must be explicitly stated that it is 
not the acetic acid in the vinegar which in this case becomes 
active, but the ferment contained in it. 

In a vinegar factory, vinegar just finished and quite turbid 
is as a rule used in the preparation of alcoholic liquid, and a 


microscopical examination shows such vinegar to contain in- 
numerable germs of vinegar ferment. This ferment on com- 
ing in contact with much air in the generators will evidently 
increase rapidly and contribute to the rapid acetification of the 
alcohol. That it is actually the ferment in the vinegar used 
which exerts a favorable effect can be shown by a simple ex- 
periment. By adding vinegar previously heated to from 140 
to 158 F. to the alcoholic liquid, the formation of vinegar in 
the generators proceeds more slowly, the ferment contained in 
the vinegar having been killed. 

The best proof, however, that the alcoholic liquid does not 
require any considerable quantity of acetic acid for its conver- 
sion into vinegar is furnished by the behavior of wine. Prop- 
erly prepared wine of a normal composition contains only a 
few ten-thousandths of its weight of acetic acid, and this must 
very likely be considered as ar product of vinous fermentation. 
If such wine be stored for years in a cool cellar, its content of 
acetic acid does not change. By, however, exposing it in a 
shallow vessel to the air at from 66 to 78 F., microscopical 
examination will show the development of vinegar ferment upon 
it, and a chemical analysis a constant increase, soon amounting 
to several per cent, of acetic acid. A fluid composed of 5 to & 
per cent, of alcohol, 94 to 95 per cent, of water, and a very 
small quantity of malt extract, acts in a similar manner. In 
many cases the vinegar ferment is developed without the fluid 
containing acetic acid. 

The alcoholic fluid to be used may from the start contain a 
sufficiently large percentage of alcohol to correspond to the de- 
sired strength of the vinegar to be made, and in this case the 
fluid has to be poured several times into the generators, it 
being impossible to convert a large quantity of alcohol into 
acetic acid by passing it through but once. By another 
method an alcoholic liquid is first prepared containing but 
little alcohol, which is almost completely converted into acetic 
acid by one passage through the generators. The fluid run- 
ning off from the generators is then further mixed with a cer- 


tain quantity of alcohol, and being poured into a generator in 
which the vinegar ferment is already accustomed to larger 
quantities of alcohol and vinegar, is also converted into acetic 
acid. More alcohol can then be added, and so on. The last 
method is evidently the best as regards the conditions of life 
of the vinegar ferment, and actually the only one by which 
the strongest vinegar (with from 12 to 13 per cent, of acetic 
acid) can be obtained in generators. 

That it is advisable only gradually to increase the content 
of alcohol in the alcoholic liquid is shown by the behavior of 
the ferment towards alcohol and acetic acid. Both bodies, if 
present in large quantities, are decidedly inimical to the prop- 
agation of the ferment, a fluid containing from 14 to 15 per 
cent, of alcohol, or as much acetic acid, being capable of check- 
ing it to such an extent as to disturb the process of production. 

Another argument against the use of the total quantity of al- 
cohol in the preparation of the alcoholic liquid to be employed 
for the first pouring, is the fact that evidently more alcohol will 
be lost by evaporation than by commencing with a fluid con- 
taining less alcohol, and adding a corresponding quantity of 
the latter after the fluid has once passed through the genera- 
tors. The quantity .of alcohol for the first pouring should be so 
chosen that the fluid running off still contains a small quantity 
of unchanged alcohol, this being an assurance that only alcohol 
and not unfinished acetic acid has undergone an alteration. 
So long as alcohol is present in the alcoholic liquid the vinegar 
ferment is almost entirely indifferent towards acetic acid, but 
after the oxidation of all the alcohol, it attacks the acetic acid 
and decomposes it to carbonic acid and water. This can be 
shown by a very simple experiment. If finished vinegar, in- 
stead of alcoholic liquid, be poured into a generator in full 
operation, the vinegar running off shows a smaller percentage 
of acetic acid than that poured in, the acetic acid missing 
having been destroyed by the ferment. 

To what an extent even smaller quantities than 14 to 15 
per cent, of alcohol or acetic acid exert a restraining influence 


upon the propagation and activity of the vinegar ferment can 
be seen in generators charged with alcoholic liquid of different 
strengths, those containing less concentrated liquid can in the 
same time form a much larger quantity of acetic acid than 
those in which a liquid is used which already contains certain 
quantities of acetic acid. Hence, the greater the quantity of 
acetic acid already contained in the alcoholic liquid, the slower 
the conversion of the alcohol still present in the acetic acid. 

It may, therefore, be laid down as a rule that the manufac- 
turer should not strive to prepare vinegar with more than about 
12 per cent, of acetic acid. Though in exceptional cases a 
product with 13 per cent, can be obtained, it will also be ob- 
served that the respective generators gradually yield a weaker 
product, or that their activity suddenly ceases to such an 
extent as to require them to be placed out of operation. 

The preparation of high-graded vinegar being undoubtedly 
subject to greater difficulties than that of a weaker product, 
the question might be raised whether the manufacture of weak 
vinegar only would not be the most suitable. This must be 
largely decided by local conditions. For a manufacturer whose 
custom lies in the immediate neighborhood, for instance, in a 
large city, the production of weak vinegar only would be advis- 
able; but if he has to send his product a considerable distance, 
the fact that the more freight has to be paid on what is of no 
value, the weaker the vinegar is, and that the expense of trans- 
porting a strong article is relatively less, deserves considera- 
tion. The consumer can readily prepare vinegar of any 
described strength by diluting the strong product with water. 

The quantity of beer required for the purpose of offering 
suitable nutriment to the vinegar ferment is very small, an ad- 
dition of 1 per cent, to the alcoholic liquid being ample. Sour 
or stale beer can of course be used. The reason for the em- 
ployment of larger quantities of beer in mixing the alcoholic 
fluids is found in the fact that the vinegar prepared from such 
mixtures sooner acquires a pure taste than that made from 
fluids containing but little beer. The addition of beer should, 



however, not exceed 15 per cent, of the total quantity of alco- 
holic liquid, as on account of the comparatively high percent- 
age of albuminous substances and the maltose, dextrin, and 
extractive matters of hops it contains, a larger quantity would 
be injurious to the process of acetic fermentation, the genera- 
tors being frequently rendered inactive by the so-called " slim- 
ing of the shavings." The production of the latter is due to 
the fact that by being partially excluded from contact with the 
air by the comparatively thick fluid passing over it, the vine- 
gar ferment deposited upon the shavings assumes the form of 
mother of vinegar which adheres to the shavings as a slimy 

The quantity of finished vinegar added to the alcoholic 
liquid varies between 10 and 33 per cent. The use of large 
quantities is however decidedly inexpedient, since the only 
effect produced by the vinegar is, as previously stated, due to 
the ferment contained in it. Of freshly prepared, turbid vine- 
gar, 10 per cent, is ample for the preparation of alcoholic 
liquid, and a greater quantity can only be considered as use- 
less ballast. 

Theoretically a certain quantity of alcohol yields exactly a 
certain quantity of acetic acid. The following table shows the 
proportions between the two bodies : 



A mixture con- 
taining the follow- 

Is composed by 
weight of 

And yields 


o> "f: 

ing per cent, of 


alcohol by volume 























3.1 98.5 






4.2 98.0 102.2 





5.2 97.6 






6.3 97.1 






7.3 . 96 6 
















' 8.9 













106 2 


12 9.7 








Practically less vinegar with a smaller percentage of acetic 
anhydride is, however, always obtained, this being due to losses 
of material caused partially by evaporation and partially by 
the oxidation of the alcohol extending beyond the formation 
of acetic acid. In preparing the alcoholic liquid these un- 
avoidable losses must be taken into consideration, and more 
alcohol has to be used for the production of vinegar with a de- 
termined percentage of acetic acid than is theoretically re- 
quired. How much more has to be taken depends on the 
kind of apparatus used and on the strength the vinegar to be 
prepared is to show. The higher the percentage of acetic acid 
which is to be obtained, the greater the losses will be, and con- 
sequently the greater the content of alcohol in the alcoholic 
liquid must be. Theoretically one per cent, of alcohol yields 
one per cent, of acetic acid, but practically the proportions are 
as follows : 

For the production of 
vinegar with a con- 
tent of acetic acid of 

5 per cent . 



Is required an alcoholic 
liquid with a content 
of alcohol of 

5.4 to 5.5 per cent. 
6.5" 0.6 

7.6 k ' 7.7 

8.7 k ' 88 
9.8 - k 99 

10.9 ^ 11.0 
11.9 " 12.1 
13.0 " 13.2 

The strength of commercial alcohol varying considerably,. it 
is of importance to the manufacturer to be able to calculate in 
a simple manner how many gallons of water have to be added 
to alcohol of known strength in order to obtain an alcoholic 
liquid with the desired percentage of alcohol. The calcula- 
tion is executed as follows : 

Suppose : 

p = per cent, of alcohol in the spirits to be used. 

E = per cent, of alcohol in the alcoholic liquid to be pre- 
pared, the quotient obtained by dividing P by E gives the 
volume to which the spirits have to be reduced by the addi- 


tion of water in order to obtain alcoholic liquid with the de- 
sired percentage of alcohol. 

Example : 

From spirits of 86 per cent. Tralles', alcoholic liquid with 

11 per cent, of alcohol is to be prepared. 

P = 86 ; E = 11 ? = 7.818. 


Hence one volume of the spirits to be used has to be brought 
to 7.818 volumes, or to one gallon of spirits 6.818 gallons of 
water have to be added. 

Examples of the composition of alcoholic liquid : 

A. Alcoholic liquid from alcohol, water, and vinegar : 

For vinegar with about 7 per cent, of acetic acid. Alcohol of 
90 per cent. Tr. 10 parts by volume, water 107, vinegar with 

7 per cent, of acetic acid 12. 

For vinegar with about 12 per cent, of acetic acid. Alcohol of 
90 per cent. Tr. 10 parts by volume, water 65, vinegar with 

12 per cent, of acetic acid 7. 

It is advisable to add about 1 per cent, of the entire volume 
of beer to the above alcoholic liquids. 

B. Alcoholic liquid from alcohol, water, vinegar, arid beer. 
For vinegar with about 5 per cent, of acetic acid. Alcohol of 

90 per cent. Tr. 10 parts by volume, water 107, vinegar with 
5 per cent, of acetic acid 13, beer 14. 

C. For vinegar with about 8 per cent, of acetic acid Alcohol 
of 90 per cent. Tr. 10 parts by volume, water 92, vinegar with 

8 per cent, of acetic acid 10, beer 9. 

In many factories it is customary not to determine the com- 
position of the alcoholic liquid by calculation, but simply to 
work according to certain receipts. Vinegar of a certain per- 
centage is obtained, but its strength cannot be predetermined 
with the same nicety as by calculating the percentage of alco- 
hol in the alcoholic liquid by the above formula. The follow- 
ing may serve as examples of such receipts : 


D. Alcohol of 50 per cent. Tr. 100 quarts, water 600, 
vinegar 900. 

.E. Alcohol of 90 per cent. Tr. 100 quarts, water 1200, 
vinegar 300. 

F. Alcohol of 90 per cent. Tr. 100 quarts, water 1350, 
vinegar 175, beer 175. 

G. Alcohol of 90 per cent. Tr. 100 quarts, water 1400, 
vinegar 300, beer 100. 

H. Alcohol of 80 per cent. Tr. 100 quarts, water, 850, 
beer 750. 

I. Alcohol of 50 per cent. Tr. 100 quarts, water 100, beer 

The mixtures A, B and C are only given as examples of how 
alcoholic liquids which yield vinegar containing the desired 
percentage of acetic acid are prepared according to receipts. 
Though it may be very convenient for the manufacturer to 
work according to such receipts as are given under D to I, 
their use without a previous examination cannot be recom- 
mended. It is far better for the manufacturer to prepare the 
alcoholic liquid according to a receipt of his own, and not 
shrink from the slight labor it involves. He has then at least 
the assurance of obtaining vinegar with exactly the percent- 
age of acetic acid desired, and is in the position to obtain an 
accurate view of the entire process of the operation. 

In the United States low wine containing 12 to 15 per cent, 
by volume of alcohol is as a rule used for the preparation of 
the alcoholic liquid. Some manufacturers prepare the sac- 
chariferous mash themselves, allow it to ferment by the addi- 
tion of yeast, and then distil off to between 12 and 15 per cent, 
by volume. As the manufacture of yeast is frequently com- 
bined with that of vinegar, the distillates obtained from the 
fermented liquors are after skimming off the yeast utilized for 
vinegar manufacturing purposes. 

Alcohol being the initial material in the preparation of 
alcoholic liquid, it is necessary to know exactly the per cent, 
by weight of alcohol it contains. With the assistance of the 


tables at the end of this volume, the content of alcohol in 
spirits of wine can be readily determined by means of the 
alcoholometer and thermometer. 

With the temperature of the spirits of wine at exactly 59 F., 
it suffices to determine its specific gravity by testing with an 
aerometer and to find the indicated figure in Table I (Hehner's 
alcohol table). The figure in the next horizontal column gives 
the per cent, by weight, and the next the per cent, by volume 
of alcohol contained in the spirits of wine examined. Tables 
II, III and IV give data relating to the proportion between 
the specific gravity and per cent, by weight and volume of 
spirits of wine of various concentration, as well as the decrease 
in volume by mixing with water. Table V shows the relation 
between the statements of Tralles' alcoholometer and a few 
others used in different places. 

The specific gravity as well as the volume of spirits of wine 
varies with the temperature, and the statements of the aero- 
meter for temperatures above the normal of 59 F. requires a 
corresponding correction, the execution of which is simplified 
by the use of Tables VI and VII. It being desirable, especially 
during the cold season of the year, to raise the temperature of 
the spirits of wine by mixing with water, Table VIII shows 
how much water has to be added in order to obtain from 
105.6 quarts of spirits of wine of known strength, whiskey of 
any desired concentration. 

In order to know exactly the yield of acetic acid which is 
obtained from a given quantity of alcohol, the acetic acid con- 
tained in the vinegar added must necessarily be taken into 
account as well as the alcohol in the beer, which is, of course, 
converted into acetic acid. It is best to make the content of 
alcohol in the alcoholic liquid so that it produces vinegar 
whose strength corresponds with that of the vinegar added. 
If, for instance, vinegar with 7 per cent, of acetic acid is used, 
alcohol of 7.G to 7.7 per cent, by weight would have to be 
employed according to the table on page 109. The following 
compilation shows the manner of preparing alcoholic liquid 
.according to rational principles. 


Suppose vinegar with 7 per cent, acetic acid is to be pre- 
pared. There would be required 

Spirits of wine of 7.6 to 7.7 per cent, by weight 105.6 quarts. 

Vinegar with 7 per cent, of acetic acid 10.56 " 

Beer . 10.56 " 

Suppose the beer contains, for instance, exactly 3 per cent, 
by weight of alcohol, hence 10.58 ounces in 10.56 quarts. 
According to this, a result of 126.78 quarts of vinegar with 
exactly 7 per cent, of acetic acid could not be expected, since 
10.56 quarts of the alcoholic liquid do not contain, as should 
be the case, 26.82 to 27.18 ounces of alcohol, but only 10.58 
ounces. Hence actually to obtain vinegar with 7 per cent, of 
acetic aci$ a sufficient quantity of spirits of wine will have 
to be added to the alcoholic liquid to increase the content of 
alcohol by 16.22 to 16.57 ounces, or spirit of wine with more 
than 7.6 to 7.7 per cent, by weight will have to be used from 
the start. 

It will, of course, be understood, that the data given above 
hold good only for the quality of the vinegar in reference to 
its content of acetic acid, the factor of the qualitative yield 
being left out of consideration. The material lost in the 
course of production amounts, as previously stated, to at least 
15 per cent., and in determining the quality of the vinegar 
to be produced this circumstance has to be taken into con- 

The content of acetic acid in vinegar can be determined with 
great ease and accuracy (up to T 5^ per cent.) by volumetric 
analysis, and from the result of such determination it can be 
readily seen how near the correct proportion of alcohol in the 
alcoholic liquid has been attained, and should the latter con- 
tain too little of it, it can be readily brought up to the deter- 
mined percentage by the addition of some strong spirit of wine, 
or, if too much, by the addition of some water. 

Constitution of the Fundamental Materials used in the Prepara- 
tion of Alcoholic Liquids. Spirits of wine, water, vinegar, and 


in most cases beer, constitute the fundamental materials for 
the preparation oi alcoholic liquids. 

. Any kind of wholesome drinking water is suitable for the 
manufacture of vinegar. Water containing a large amount of 
organic substance or living organisms, or which possesses a 
specific taste from the admixture of salts, should not be used 
under any circumstance. 

Many well-waters are very hard, i. e., they contain a com- 
paratively large quantity of calcium carbonate in solution. If 
such water be used in the preparation of alcoholic liquid, the 
calcium carbonate is decomposed by the acetic acid and the 
vinegar contains a corresponding quantity of calcium acetate 
in solution. Other well-waters contain a large quantity of 
gypsum (calcium sulphate) in solution. This salt is not 
changed by acetic acid, but remains partially dissolved in the 
finished vinegar. 

When water very rich in gypsum is mixed with alcohol the 
fluid, at first entirely clear, becomes in a short time opalescent 
and finally perceptibly turbid. After long standing a very 
delicate white sediment separates on the bottom of the vessel, 
the fluid becoming again clear. This phenomenon is ex- 
plained by the fact that gypsum, while soluble in water with 
comparative ease, is next to insoluble in a fluid containing 
alcohol, and hence gradually separates in the form of minute 

Water containing no gypsum but much calcium carbonate 
shows after mixing with spirits of wine a similar behavior ; it 
at first becoming turbid and again clear after separating a deli- 
cate white precipitate. Calcium carbonate is soluble only in 
water containing a corresponding quantity of carbonic acid ; 
on standing in the air the carbonic acid escapes and the cal- 
cium carbonate separates. 

This behavior of water when mixed with alcohol and stand- 
ing in the air can be utilized for the almost complete separation 
of the gypsum and calcium carbonate. Mixtures of water and 
alcohol, in the proportion the alcoholic liquids are to have, are 


first prepared and the fluid stored in barrels in a warm apart- 
ment near the workroom. The mixtures at first turbid be- 
come clear after some time, and are then drawn off from the 
sediment by means of a rubber hose. A comparative exami- 
nation of the water and the mixtures shows that the latter 
contain only very small quantities of gypsum and calcium 
carbonate in solution. 

River water, though generally soft, i. e., poor in the above- 
mentioned salts, is seldom sufficiently clear to be used without 
previous filtration. It is further very likely that the small 
worms, known as vinegar eels, which frequently become very 
annoying in vinegar factories, reach the alcoholic liquid 
through the use of river water, and, therefore, the use of well- 
water wherever possible is recommended. 

The constitution of the spirits of wine used in the prepara- 
tion of the alcoholic liquids is of great importance, the bouquet 
of the vinegar to be prepared depending on it. Commercial 
spirits of wine always contains certain foreign bodies known as 
" fusel oils," which have a very intense odor and can only be 
removed by careful rectification. For the vinegar manufac- 
turer it is of great importance to know the behavior of spirits 
of wine containing fusel oil when converted into acetic acid, 
and a number of experiments with different varieties (from 
potatoes, grain, wine) have shown the respective vinegar also 
possessed of a specific odor, differing, however, from that of 
the original fusel oil and developing by storing into a bouquet 
of a peculiar but agreeable odor. This phenomenon is ex- 
plained by the fact that the energetic oxidizing process which 
takes place in the generators extends not only to the alcohol 
but also to the other bodies present, and the greater portion of 
the fusel oils is thereby converted into odoriferous combina- 
tions or compound ethers. 

By treating potato fusel oil (amyl alcohol) with sulphuric 
acid and an acetate, amyl acetate is formed which in a diluted 
state smells like jargonelle pears and is used by confectioners 
under the name of " pear essence " for flavoring so-called fruit 


bonbons. The same process would seem to take place by 
passing spirits of wine containing potato fusel oil through the 
generators, the vinegar prepared from such spirits of wine 
showing an agreeable odor immediately when running off 
from the generators, while vinegar prepared from entirely pure 
spirits of wine has at first a stupefying smell and acquires a 
harmonious odor only by long storing. 

It would, therefore, be advisable for the manufacturer who 
works with potato alcohol not to use the highly rectified pro- 
duct, but a mixture of it and of crude spirits containing fusel 
oil, the vinegar prepared from such a mixture acquiring a 
more agreeable odor than that obtained from the rectified pro- 
duct. How much of the crude spirits has to be used can only 
be determined by experience, but, as a rule, only enough 
should be taken to assure the conversion of the entire quantity 
of amyl alcohol present. 

The fusel oil contained in spirits of wine from grain consists 
largely of a mixture of fatty acids, and offers far greater resist- 
ance to oxidation in the generators than amyl alcohol. The 
same may be said of cenanthic ether, the fusel oil of brandy. 
In working with alcoholic liquid prepared with a large quan- 
tity of grain spirits containing fusel oil, the smell of un^ 
changed fusel oil is perceptible in the vinegar besides the odors 
of the products of its decomposition. With the use of small 
quantities of grain spirits containing fusel oil, vinegar possess- 
ing a more agreeable odor than that from entirely pure spirits 
is obtained. 



WHEN the factory is in proper working order the further 
execution of the operation is very simple, it being only neces- 
sary to admit at stated intervals to the generators a previously 


determined quantity of alcoholic liquid and to collect the 
vinegar running off. With the operation running its proper 
course, attention has only to be paid to the maintenance of the 
correct temperature in the workroom and in the generators, 
the chemical process proceeding regularly without further 
assistance. In many cases, however, deviations from the reg- 
ular order occur, and are due to external influences, such as 
changes in the temperature in the generators, variations in 
the composition of the alcoholic liquid, etc. They will later 
on be discussed in a special chapter. 

The capacity of a factory depends on the number of gen- 
erators in operation. A regularly working generator is sup- 
posed to be capable of daily converting 3 liters (3.16 quarts) 
of absolute alcohol, and this quantity will be taken as the basis 
for calculating the execution of the operation. If, for instance, 
vinegar with 8 per cent, of acetic acid is to be manufactured, 
alcohol of 8.8 per cent, by weight has to be used, and to pre- 
pare this, 3 liters of 100 per cent, alcohol have to be reduced 
with water, so that, according to Table I, the fluid shows a 
specific gravity of 0.9858 at 59 F. According to Table III, 
8.98 liters of water have to be added to every liter of 100 per 
cent, alcohol to obtain spirits of wine of 8.8 per cent, by 
weight ; hence 3 liters have to be compounded with 2G.94 
liters of water (according to Table III, alcohol with 90 per 
cent, by volume of alcohol contains 11.80 per cent, by volume 
of water, 80 per cent, alcohol 22.83, etc., which has to be 
taken into consideration in making the dilution). 

According to Table III, the contraction in this case amounts 
to 0.799 part by volume for every 100 parts by volume of the 
fluid. Hence the 3 liters of 100 per cent, alcohol yield, when 
diluted to spirits of wine of 8.8 per cent, by weight, 26.94 + 3 
= 29.94 liters of fluid. Actually the quantity is somewhat 
smaller, as in mixing alcohol with water a decrease in vol- 
ume takes place. If the alcoholic liquid is to contain 10 per 
cent, each of vinegar and beer, the quantity of fluid is as 
follows : 


Dilute spirits of wine ........ 29.94 litres. 

Vinegar with 8 per cent, acetic acid ..... 2.994 " 

Beer 2.994 " 


Hence the quantity to be worked in a generator in the course 
of a day amounts to 35.928 liters, or taking into account the 
quantity of alcohol (about 90 grammes or 3.17 ozs.) contained 
in the beer, to about 36 liters. This quantity has to be divided 
among the separate pourings so that in a working time of 15 
hours, 2.4 liters would have to be poured every hour. How- 
ever, by this method, too much alcohol would, on the one 
hand, be lost by evaporation, and, on the other, the work of 
the generators would be comparatively slow, since, as is well 
known, the conversion into acetic acid is effected with greater 
rapidity when the alcoholic liquid contains less alcohol. 
Hence it is advisable to use in the commencement of the oper- 
ation a fluid which contains only about one-half or two-thirds 
of the total quantity of alcohol, and to add a corresponding 
quantity of strong alcohol to every fresh pouring. 

When all the alcohol has been converted into acetic acid, 
the vinegar ferment, as previously mentioned, commences^with 
great energy to oxidize the latter to carbonic acid and water, 
and hence the quantity of spirits of wine added to the alcoholic 
liquid must be sufficiently large for the vinegar running off to 
contain always a minute quantity of it. 

Much has been written about this gradual strengthening of 
the alcoholic liquid with alcohol, and explicit directions are 
given as to the original composition of the alcoholic liquid, as 
well as to how much, how often, and when the alcohol is to be 
added. These directions may have proved useful in many 
cases, but local conditions exert too great an influence upon 
the process of manufacture for them to be of general value. 
Besides the content of alcohol in the alcoholic liquid, the size 
of the generators, the strength of the draught in them, the 
temperature prevailing in the workroom and in the interior of 
the generators, are factors which must be taken into consider- 


ation in determining on a plan of operation actually adapted 
to existing conditions. 

The size of the generators is, of course, fixed once for all. 
In a proper state of working the strength of the current of air 
must be so regulated that the temperature in the interior of the 
generators is only about 4.5 F. higher than that of the work- 
room, which is readily accomplished with a suitable central 
heating apparatus. There still remains the determination of 
the most favorable proportion of the content of alcohol in the 
alcoholic liquid to be first used and its gradual strengthening 
by the addition of spirits of wine, which can only be effected 
by a chemical examination of the fluid running off from the 

This chemical examination is restricted to the accurate de- 
termination of the quantity of acetic acid in the fluid and to 
that of the alcohol to 0.1 per cent. The determination of the 
acetic acid is effected by volumetric analysis, and with some 
experience requires four to five minutes for its execution. For 
the determination of the alcohol an examination with the 
ebullioscope suffices, which can also be accomplished in four to 
five minutes.* These two determinations, which every vine- 
gar manufacturer should be able to make, are the only means 
of obtaining an accurate control of the working of the factory, 
and also serve, of course, for settling the exact plan of opera- 
tion from the start. 

If, with reference to the example given above, vinegar with 
8 per cent, of acetic acid is to be prepared, the alcoholic liquid 
must contain a total of 8.8 per cent, by weight 'of alcohol. 
Now if the manufacture is commenced with an alcoholic liquid 
containing the total quantity of water, vinegar, and beer, but, 
for instance, only 5 per cent, by weight of alcohol, the follow- 
ing method will have to be pursued in order to accurately 
determine when and how much alcohol has to be added. 

The first portion of the alcoholic liquid being poured into 

* The manner of executing these determinations will be described later on. 


the generator, the fluid running off is tested as to its content 
of acetic acid and alcohol, the test being repeated after the 
second and each successive pourings. Each test must show an 
increase in the content of acetic acid and a decrease in that of 
alcohol, and the latter must finally have disappeared so far 
that a new addition of alcohol seems to be in order. If the 
test after the third pouring shows the fluid to contain only 0.3 
to 0.4 per cent, of alcohol, this quantity would be quickly and 
completely oxidized in the fourth pouring, and a certain quan- 
tity of acetic acid be at the same time destroyed. Hence it is 
necessary to add, for instance, 2 per cent, by weight of alcohol 
to the alcoholic liquid before the fourth pouring. When this 
2 + 0.3 or 2 -f- 0.4 per cent, of alcohol, which the alcoholic 
liquid now contains, is again reduced, after the sixth or 
seventh pouring, to 0.3 or 0.4 per cent., the last addition of 
1.8 per cent, of alcohol is made, the total quantity of alcohol, 
5 + 2 + 1.8 = 8.8 per cent, having now been used. 

When, after a certain number of pourings, a test of the fluid 
running off shows a content of 8 per cent, of acetic acid and 
only 0.1 or 0.2 per cent, of alcohol (a small remnant of alcohol 
should always be present) the process is considered as finished, 
and a further pouring into the generator would not only be 
useless labor, but contrary to the end. in view, since, after the 
complete oxidation of the last remnants of alcohol, that of 
acetic acid would immediately commence, and weaker vinegar 
would be obtained after each pouring. 

If a generator works up the quantity of alcoholic liquid in- 
tended for 12 or 15 hours in 10 or 12 hours, it is more proper, 
on account of the diminished loss by evaporation, to induce 
slower work by decreasing the draught of air in order to 
maintain the rule that a generator has to work up 3 liters of 
absolute alcohol in the working time of a day. 

After controlling for several days the work of a generator, 
by examining the products as to their contents of acetic acid 
and alcohol, the plan of operation resolves itself from the 
results of these tests, since then it is accurately known after 


how many pourings of an alcoholic liquid of known composi- 
tion an addition of alcohol is required ; further, after how many 
pourings a finished product is present, so that directions for 
the progress of the operation can be given to the workmen ac- 
cording to time and quantities. The normal working of the 
generators can always be controlled by from time to time re- 
peating the test of the products. 

Now, suppose the work in a newly arranged factory having 
reached the point at which acetification is complete, the actual 
production, according to the old method, will be gradually 
commenced by pouring in alcoholic liquid of corresponding 

The shavings of the generator having been saturated with 
acetifying vinegar, the latter is partially replaced by the fluid 
poured in, and as much as is expelled runs off. If the gener- 
ator should at once commence to work regularly, the tempera- 
ture in its interior would be observed to rise, though it would 
at first be impossible to establish a change in the composition 
of the fluid running off. Slight variations in the content of 
acetic acid and a small percentage of alcohol could be deter- 
mined in the fluid only after the acetifying vinegar originally 
present has been entirely expelled by a series of pourings. 

With the progress in the manufacture of vinegar, it became 
customary to produce the strongest vinegar possible, the so- 
called triple vinegar, with about 12 per cent, of acetic acid. 
On account of its greater commercial value, this article could 
be sent greater distances, the consumer reducing it to a weaker 
product by the addition of water. 

To prepare directly vinegar with such a high percentage of 
acetic acid, it would, however, be necessary to acetify all the 
generators with vinegar of the same strength, and to use alco- 
holic liquid very rich in alcohol. By this method the losses of 
alcohol by evaporation, and also of acetic'acid, would, however, 
be so great as to make the product too expensive. Further- 
more, the work would require most careful and constant atten- 
tion on account of the difficulty with which oxidation takes 


place in alcoholic liquid containing much acetic acid, and it 
might only too readily happen that the generators suddenly 
worked with less vigor, i. e., that the content of acetic acid in 
the vinegar running off would decrease, and the quantity of 
alcohol remaining unchanged correspondingly increase. 

On account of these difficulties, it has become customary to 
charge the greater number of generators with alcoholic liquid 
yielding the so-called double vinegar with about 8 per cent, of 
acetic acid, and to work this vinegar with the addition of the 
required quantity of strong spirits of wine in a number of 
generators, which, of course, must be acetified with 12 per 
cent, vinegar. 

It will be readily understood that the employment of this 
method is not only advantageous for the production of vinegar 
with the highest attainable content of acetic acid, but also for 
general purposes. Passing the alcoholic liquid but once 
through the generators does not suffice, even for vinegar with 
only 5 to 6 per cent, of acetic acid, an examination always 
showing a considerable quantity, J per cent, and more, of un- 
converted alcohol in the vinegar running off. The conversion 
of alcoholic liquid with a small content of alcohol into vinegar 
by one pouring can, to be sure, be accomplished, but it neces- 
sitates the use of very tall generators and a constant struggle 
with difficulties on account of the irregular draught of air, 
caused by the packing together of the shavings. 

Group System. Theoretically, as well as practically, the 
group system may be considered as the perfection of the quick 
process. The principle of the operation consists in the divi- 
sion of the generators into two or three groups, each group 
preparing vinegar of determined strength. In factories which 
do not produce vinegar of the greatest attainable strength (12 
per cent, vinegar), but only double vinegar with about 8 per 
cent, of acetic acid, two groups might suffice. The manufac- 
ture of a product of the greatest attainable strength being, 
however, advisable in most cases, it is recommended to ar- 
range the factory for continuous work with three groups of 


For this purpose the number of generators must be divisible 
by three; Hence 3, 6, 9, 12, etc., generators have to be pro- 
vided, of which 1, 2, 3, 4, etc., form one group, so that, for in- 
stance, in a factory working with 24 generators belonging to 
one group with the same number, we have groups I, II and 
III, and in acetifying and operating, the generators belonging 
to one group are treated in the same manner. 

For the preparation of the strongest vinegar (12 per cent.) 
the generators belonging to group I can, for instance, be acet- 
ified with vinegar of 6 per cent, acetic acid, those of group II 
with 9 per cent, vinegar, and those of group III with 12 per 
cent, vinegar. The process of operation is then as follows : 

Group I'. The generators belonging to this group are 
charged with an alcoholic liquid which yields vinegar 
with a content of 6 per cent, acetic acid, and the fluid 
running off is poured back into the generators until a 
test shows the alcohol, with the exception of a small 
remnant, to have been converted into acetic acid. To 
this vinegar is then added sufficient strong alcohol to 
form an alcoholic liquid which will yield 9 per cent, 

Group II. The alcoholic liquid for 9 per cent, vinegar- is 
poured into the generators belonging to group II, the 
pourings being repeated until all but a very small quan- 
tity of the alcohol is oxidized. The vinegar running 
off is again compounded with sufficient alcohol to form 
alcoholic liquid for 12 per cent, vinegar, and is brought 

Group III. The pourings are here repeated until the oxi- 
dation of alcohol is nearly complete. The finished 
product is then stored or clarified. 

As will be seen from the above, in operating according to 
the group system, the entire factory is, so to say, divided into 
three factories, I, II, and III, of which I produces vinegar of 
6 per cent., II vinegar of 9 per cent., and III vinegar of 12 


per cent. The product of I, after having been converted by a 
suitable addition of alcohol into alcoholic liquid adapted for 
the preparation of 9 per cent, vinegar, is directly used for 
charging the generators of group II, and that of II for charg- 
ing III. 

The generators belonging to one group having been aceti- 
fied with vinegar of the same strength, the fluid running off 
from one generator need not necessarily be returned to it. 
The work can, therefore, be simplified by conducting the fluid, 
running off from all the generators by means of a suitable 
pipe-system into a common receiver instead of allowing the 
fluid, which has passed through a generator, to collect under 
a false bottom and then drawing it off and returning it to the 
same generator. If, for instance, 8 generators belong to one 
group and 3 litres have at the same time been poured into 
each, the passage of the liquid through all the generators will 
be shown by a measuring scale placed in the common receiver, 
indicating that the latter contains 3x8=24 litres. 

The samples for determining the content of acetic acid and 
alcohol are taken from the common receiver, and the latter 
also serves for the conversion of the vinegar, after it has ac- 
quired the percentage of acid attainable in that group, into 
stronger alcoholic liquid by the addition of alcohol. In order 
to effect an intimate mixture, and at the same time prevent 
the vinegar ferment floating in the fluid from suffering injury 
by coming in contact with the highly concentrated spirits of 
wine, the required quantity of the latter is introduced in a 
thin jet and with constant stirring. 

In many factories it is customary from time to time to alter- 
nate with the pourings in the groups or " to cross the genera- 
tors." By this " crossing " the alcoholic liquid, which, accord- 
ing to the above method, would, for instance, pass from group 
II to group III, is poured into group I, so that after some time 
the generators of this group are converted into generators of 
group III (with 12 per cent, acid), and group III becomes 
group I, it now containing the weakest alcoholic liquid (with 6 


per cent. acid). Crossing, however, cannot be recommended, 
because a sudden change in the constitution of the nourishing 
fluid always exerts an injurious influence upon the propaga- 
tion of the vinegar ferment. 

Recourse to crossing is most frequently had for the purpose 
of " strengthening " the vinegar ferment by working weaker 
alcoholic liquid in the generators of one group generally that 
which yields the strongest vinegar when their activity dimin- 
ishes. This strengthening of the ferment can, however, be 
effected in a more simple and suitable manner by diminishing 
the quantity of alcoholic liquid poured in at one time and by 
increasing the draught of air, and the consequent change of 
temperature in the generators, so that the principal reasons for 
" crossing the generators " (which many manufacturers consider 
indispensable) have no force. 

Group System with Automatic Contrivances. If the pourings 
of the alcoholic liquid are to be effected at determined inter- 
vals by an automatic contrivance, the group system as de- 
scribed on p. 122 et seq. should be used. The operation of 
such a factory is very simple. As seen from the description 
of the arrangement, the generators are divided into three 
groups, I, II, and III. Besides the generators each group must 
be provided with a reservoir, which may be designated R, and 
a collecting vessel C. (The other component parts, distribu- 
ting arrangements and conduit, can here be left out of con- 

For the production of 12 per cent, vinegar in such a factory 
it is the best so to prepare the alcoholic liquid for the several 
groups that 

Group I contains alcoholic 

liquid with . . . . 6 p. c. acetic acid and 6.5 to 6.6 p. c. alcohol. 

Group II contains alcoholic 

liquid with .... 9 " +3.2 to 3. 3 

Group III contains alco- 
holic liquid with . . . 12 " " +3.2 to 3.3 


Group I having been acetified with 6 per cent, vinegar, 
group II with 9 per cent, vinegar, and group III with 12 per 
cent, vinegar, the fluid running off from group I, after being 
compounded with 3.2 to 3.3 per cent, of alcohol, is used in 
group II as alcoholic liquid for 9 per cent, vinegar, and yields 
9 per cent, vinegar, which after being again compounded with 
3.2 to 3.3 per cent, of alcohol, yields 12 per cent, vinegar after 
having passed through group III. 

The uninterrupted working of the generators constituting 
one of the principal advantages of the automatic system, it is 
advisable to regulate the automatic contrivance so that but a 
small quantity of alcoholic liquid be at one time poured out, 
and to fix the intervals between two pourings so that the sec- 
ond pouring takes place after about one-half of the first has 
run off. Under these conditions there will be in the lower 
half of the generator an alcoholic liquid in which the alcohol 
is nearly as much oxidized as it can be by one passage through 
the generator, while in the upper half will be fresh alcoholic 
liquid in which oxidation is continued without interruption. 
A further advantage obtained by this is that a generator will 
yield quantitatively more than one working only 15 to 16 
hours ; further, the conditions of temperature in the interior 
of the generator remain always the same, and the ferment con- 
stantly finds nutriment. 

The alcoholic liquid for group I is pumped into the reser- 
voir B^ and passes through the generators of group I into the 
collecting vessels C r All the alcoholic liquid having run off 
from RV the fluid collected in C v after having been tested as 
to its content of acetic acid, is for the second time pumped in- 
to R! and passes again through the generators of group I. The 
automatic contrivance is so regulated that the alcoholic liquid, 
after being twice poured in, contains but a very small remnant 
of alcohol. 

To the vinegar of 6 per cent, collected in G l is now added 
3.2 to 3.3 per cent, by weight of alcohol, best in the form of 
80 to 90 per cent, spirits of wine. The resulting stronger alco- 


holic liquid is at once pumped into J? 2 , and passing through 
the generators of group II reaches the collection vessel C 2 . It 
is then tested, pumped back into .7? 2 , and again collected in C 2 . 
If it now shows the required strength, it is mixed with the 
second portion of 3.2 to 3.3 per cent, by weight of alcohol and 
is pumped into J? 3 , and after passing twice through the gene- 
rators collects as finished vinegar in (7 3 . 

It will be seen from the above description of the process that 
in making the tests, the product of all the generators of one 
group is treated as a whole. A disturbance may, however, 
occur in either one of the generators, and it would take consid- 
erable time before its existence would be detected by a change 
in the constitution of the entire product. The thermometer 
with which each generator is provided is, however, a reliable 
guide as to the activity of the latter, and if it shows in one of 
them a temperature varying from 37 to 49 F. from that pre- 
vailing in the others, it is a sure sign of the respective generator 
not working in the same manner as the others, and the product 
running off from it should be tested by itself as to its content 
of acetic acid and alcohol. 

Generally it will contain either no alcohol or very much of it. 
In the first case the temperature of the respective generator is 
higher than that prevailing in the others, and its activity has 
to be moderated by decreasing the admission of air; in the 
other case, the generator works too sluggishly, and the differ- 
ence is sought to be equalized by increasing the current of air 
or giving a few pourings of somewhat warmer alcoholic liquid. 
With a good heating apparatus producing a uniform tempera- 
ture in the workroom such disturbances will, however, but 
seldom happen, and by the use of the above means the normal 
working of the generators can be restored. 




IN no other industry based upon the process of fermentation 
are irregularities and disturbances of such frequent occurrence 
as in the manufacture of vinegar. Besides the nourishing sub- 
stances dissolved in the fluid and free oxygen, the vinegar fer- 
ment requires a certain temperature for its abundant propaga- 
tion, by which alone large quantities of alcohol can in a short 
time be converted into acetic acid. By exercising the neces- 
sary care for the fulfillment of these conditions serious dis- 
turbances can be entirely avoided, and the slighter ones due 
to insufficient acetic fermentation of the ferment readily re- 

As regards- the nourishing substances of the ferment, irregu- 
larities can actually occur only in working continuously with 
an alcoholic liquid composed exclusively of water and alcohol. 
In such alcoholic liquid the nitrogenous substances necessary 
for the nutriment of the ferment are wanting, nor are the phos- 
phates present in sufficient quantity. The consequences are 
the same as in every insufficiently nourished ferment-organism 
The fermenting activity suddenly diminishes, propagation pro- 
ceeds sluggishly and ceases entirely if abundant nutriment is 
not introduced. Hence it may happen that from a generator 
containing alcoholic liquid composed only of water, alcohol, 
and vinegar, the greater portion of the alcohol suddenly runs 
off unchanged, the temperature in the interior of the generator 
at the same time falling, and the draught of air ceasing soon 
afterwards. When these phenomena appear it should first be 
ascertained whether the disturbance is not due to too slight a 
current of air. For this purpose the draught-holes are entirely 
opened, and if the temperature rises the generator gradually 
resumes its normal working. If, however, no improvement is 
observed, the disturbance is due to defective nutriment, and the 
composition of the alcoholic liquid has to be changed, which is 


best effected by the addition of a few per cent, of beer or of 
fermented alcoholic mash, either one of them containing a suffi- 
cient quantity of phosphates and albuminous substances. The 
use of sweet beer wort or malt extract has also been highly 
recommended for ''strengthening weak-working generators." 
These substances also furnish albuminous bodies and phos- 
phates to the alcoholic liquid, but they also contain maltose and 
dextrin, and as it has not yet been ascertained whether the 
latter and the carbohydrates in general can be consumed and 
digested by the ferment, they possibly may pass unchanged 
into the vinegar. Honey and glucose are also sometimes used 
for strengthening purposes, but while the former might be 
useful on account of the abundance of salts and nitrogenous 
substances it contains, no substances of any value to the fer- 
ment are present in the latter. At any rate the addition of 
beer, mash, or malt extract is to be preferred. 

An addition of phosphate to the alcoholic liquid is also 
claimed to produce a favorable effect upon the propagation of 
the ferment. Commercial phosphoric acid is dissolved in 
water and the solution neutralized with potassium, a solution 
of potassium phosphate being in this manner obtained. The 
vinegar ferment being very sensitive towards this salt, a very 
small quantity of the solution, about 10 ouo of the weight of the 
alcoholic fluid may be added. The experiment must, how- 
ever, be made very cautiously, and the effect upon the working 
of the generator carefully noted. 

Disturbances ascribable to the quantity of newly formed Acetic 
Acid. Under proper working conditions the alcoholic liquid 
brought into the generators should be completely converted 
into vinegar, and theoretically, the product running off show 
the same strength a? the vinegar used for acetification. Act- 
ually there are, however, slight variations not exceeding a few 
tenths of one per cent. Should greater differences appear, a 
disturbance actually exists and may show itself in various ways. 
The generator may work too feebly or too vigorously. In the 
first case the content of acetic acid in the fluid running off de- 


creases considerably, while that of alcohol increases. The 
process of the formation of vinegar is, so to say, only half 
carried through, a great portion of the alcohol being converted, 
not into acetic acid, but into aldehyde. The greater portion 
of this combination is lost to the manufacturer on account of 
its low boiling point (71.6 F.), it escaping in the form of vapor, 
the stupefying odor of which when noticed in the air of the 
workroom is accepted by all manufacturers as indicative of a 
disturbance in the regular working of the generators. This 
odor, however, becomes perceptible only after the disturbance 
has continued for some time, with the loss of a considerable 
quantity of alcohol. Hence the control of the working of the 
generators by a frequent determination of the acid becomes 
necessary. Repeated observations of the thermometer also 
furnish valuable hints about the progress of the chemical pro- 
cess. The temperature in this case remains only for a short 
time unchanged and soon falls, far less heat being liberated in 
the mere conversion of alcohol into aldehyde than when oxi- 
dation progresses to the formation of vinegar. These phe-, 
nomena are indicative of the generator not being able to master 
the alcoholic liquid introduced, and may be due to the pourings 
being too large, or the temperature of the alcoholic liquid 
poured in being too low, or finally to an insufficient draught 
of air. 

To restore the generator to a proper state of working, it is 
best to try first the effect of smaller pourings, and then an in- 
creased draught of air. If the disturbance was due to an in- 
sufficient draught of air, the temperature soon rises and the 
generator will be able to work up the regular quantity of alco- 
holic liquid. By the use of alcoholic liquid of a somewhat 
higher temperature the restoration of the normal conditions 
can be accelerated. 

A decrease in the content of acetic acid in the fluid running 
off from the generators without the presence of alcohol being 
shown, indicates a too vigorous process of oxidation, the alco- 
hol being not only oxidized to acetic acid, but the latter further 


into carbonic acid and water. The temperature in the interior 
of the generators rises considerably, about 45 F., above that 
of the workroom. 

In this case the restoration of the respective generator to a 
proper state of working is not difficult and can be effected in 
two ways, either by considerably decreasing the ventilation ot 
the generator, or by pouring in a larger quantity of alcoholic 
liquid than previously used. 

Heating of the generators is generally due to faulty con- 
struction. Generators of large dimensions, as a rule, become 
too warm much easier than smaller ones, the phenomenon also 
appearing more frequently in summer than in winter; and 
" too warm " being just as injurious to the efficacy of the gen- 
erators as " too cool," they must, during the warm season of 
the year, be as carefully protected against too high a tempera- 
ture as against cooling during the cold season. This is effected, 
on the one hand, by a suitable ventilation of the workroom 
during the night, and, on the other, by the use of alcoholic 
liquid of a somewhat lower temperature during the hottest 
season of the year. Moreover, disturbances from too high a 
temperature of the exterior air need only be feared in coun- 
tries with a very warm climate. 

It has been frequently proposed to counteract a too vigorous 
activity of the generators by the addition of a little oil of cloves 
or salicylic acid which have the property of checking fermenta- 
tion. Salicylic acid, especially,, is an excellent corrective for 
the faulty working of a generator. It has to be used, however, 
with great caution and only be added by the TTOOITO f the 
weight of the alcoholic liquid, and just in sufficient quantity 
to attain the desired result. A large amount is injurious to 
the ferment and might kill it. 

" Sliming " of the Shavings in Generators. This disturb- 
ance sometimes occurs in a vinegar plant, and its progress gen- 
erally ends in throwing the entire operation into complete 
disorder so that finally no more vinegar can be produced. 
After fruitless experiments nothing remains but to empty the 


generator, wash the shavings with hot water and, after drying 
and steeping them in hot vinegar, return them to the gen- 

Sliming may be due to infection by foreign bacteria and 
fungi, as well as to super-oxidation and the accumulation of 
larger quantites of alcohol in the shavings which affects the 
bacteria to such an extent that they have no longer the power 
of forming acetic acid or only very sinall quantities of it, but 
only aldehyde, the intermediate product between alcohol and 
acetic acid. 

The trouble begins to show itself by the generators commenc- 
ing to work irregularly. While formerly a certain quantity of 
alcohol was after a fixed number of pourings converted into 
acetic acid, a large number of pourings are. now required to 
attain the same result. The generators work slower and the 
heat in their interior decreases. By heating the workroom 
more strongly only a temporary improvement is brought about, 
and the production of the generators becomes less and less, and, 
finally, so low that work has to be interrupted. When the 
disturbance has progressed thus far a disagreeable musty, in- 
stead of the characteristic acid odor, is perceived in the work- 
room. By allowing one of the faulty working generators to 
stand for a few days without charging it with alcoholic liquid, 
the temperature in the interior may rise considerably and pro- 
ducts of putrefaction be developed to such an extent as to 
taint the air of the workroom. 

Long before this phenomenon becomes apparent, an altera- 
tion takes place in the shavings. A shaving taken from a 
normally working generator has the ordinary appearance of 
wet wood ; but one taken from a generator working in the 
above-mentioned faulty manner is coated with a slimy mass, 
which is somewhat sticky, and can be drawn into short threads. 
Viewed under the microscope this slimy coating presents a 
structureless mass, throughout which numerous germs of vine- 
gar ferment are distributed and sometimes the vinegar eels. 
Independently of the presence of the latter, this slimy coating 


presents the same appearance as the so-called mother of vine- 
gar. By placing a shaving coated with slime upright in a shal- 
low dish, and filling the latter f the height of the shaving with 
alcoholic liquid, the previously described delicate veil of vine- 
gar ferment develops upon the surface, while the portion of the 
shaving covered by the fluid is surrounded by flakes distin- 
guished by nothing from mother of vinegar. Hence there can 
scarcely be a doubt that the slimy coating actually consists of 
the same structure to which the term mother of vinegar (see 
p. 21) has been applied, and in searching for the cause of the 
formation, it will generally be found to be due to conditions 
similar to those which give rise to the formation of the latter. 
An alcoholic liquid overly rich in young beer containing much 
albumen, or one to which much malt extract or young fruit- 
wine has been added, is apt to give rise to the formation of 
mother of vinegar in the generators. The slimy coating thus 
formed upon the shavings envelops the vinegar ferment and 
prevents its immediate contact with the air ; consequently the 
alcoholic liquid does not encounter as much ferment as is re- 
quired for the complete oxidation of the alcohol, and the gen- 
erators become weaker. This decrease in the production is, of 
course, followed by a lower temperature in the generators, and 
consequently by a decrease in the propagation of the ferment, 
these unfavorable conditions finally becoming so great as to 
bring the activity of the generators to a standstill. 

The settlement of vinegar eels upon the surface of the mother 
of vinegar has no connection with sliming. Should, however, 
large masses of these animalcules happen to die in the genera- 
tors for want of air, due to the constantly decreasing draught, 
they quickly putrefy on account of the high temperature, and 
give rise to the most disagreable odors. 

A careful manufacturer will observe sliming at the com- 
mencement of the evil, when it can be remedied without much 
difficulty. First of all, the composition of the alcoholic liquid 
must be changed by discontinuing the use of fluid containing 
many carbohydrates and albuminous substances, such as 


young beer, malt extract, young fruit-wine, it being best to 
use alcoholic liquid of water, vinegar, and alcohol only until 
the generators are entirely restored to a normal working 
condition. The activity of the ferment is at the same time 
increased by a stronger draught of air in the generators and 
by raising the temperature of the workroom. In a few days 
the generators will be again in a proper working condition, 
which is recognized by the normal conversion of alcohol into 
acetic acid. 

If, however, the evil has progressed to a certain extent 

FIG. 36. 

nothing can be done but to empty the generators. Though 
considerable labor is connected with this operation, there is 
no further use of experimenting, since such nonsensical addi- 
tions as beer-yeast, tartar, honey, etc., which have been pro- 
posed as remedies, only accelerate the final catastrophe the 
entire cessation of the formation of vinegar. Should a dis- 
turbance occur which cannot be accounted for by defective 
nutriment of the ferment, want of air> or an incorrect state of 
the temperature, the condition of the shavings should be at 
once examined into, and if they show the first stages of sliming 



the evil should, if possible, be remedied by changing the com- 
position of the alcoholic liquid. If the new alcoholic liquid 
contains only water, vinegar, and alcohol, sliming cannot 
progress, and the layers of slime upon the shavings will in a 
short time disappear, they being partially utilized in the nu- 
triment of the ferment, and partially mechanically washed 
off by the alcoholic liquid running down. 

Disturbances due to Vinegar Eels. In many factories filamen- 
tous structures scarcely visible to the naked eye will frequently 
be observed in the vinegar. When viewed under the micro- 

FIG. 37. 

scope they will be recognized as animalcules, to which the 
term vinegar eel (Anguilla aceti) has been applied on account 
of their form slightly resembling that of an eel. Fig. 36 
shows a microscopical picture of a drop of vinegar swarming 
with vinegar eeis slightly magnified, and Fig. 37 a vinegar 
eel greatly magnified. 

The animalcule consists of a cylindrical body running to a 
sharp point. The mouth-opening is covered with small knots ; 
the throat is globular and passes directly into the long intes- 
tinal tube. The eggs are placed at about the centre of the 


body in two tubes which unite to a plainly perceptible aper- 
ture. The average length of the female is 0.0682 Paris inch 
and that of the male 0.0486, the former being larger than the 
latter in proportion of 1 : 1.3. 

Vinegar eels can exist in dilute alcohol of the strength used 
in making vinegar as well as in dilute acetic acid. In 
alcoholic liquid containing much alcohol and acetic acid they 
do not thrive as well as in weak liquid. Their part in the 
manufacture ol vinegar is under .all conditions an injurious 
one. The vinegar ferment can only carry on its function 
correctly when vegetating upon the surface of the fluid and in 
contact with air. The vinegar eel being an air breathing 
animal always seeks the surface, and in an alcoholic liquid 
which contains it, and upon whose surface an abundance of 
ferment grows, actual combats between animalcule and fer- 
ment can be observed, the former striving to force the latter, 
which is inimical to its existence, under the surface and thus 
render it harmless. (Submerged vinegar ferment, as is well 
known, changes its conditions of existence aud becomes mother 
of vinegar.) If the conditions are favorable for the develop- 
ment of the animalcules, the latter overcome the ferment and 
submerge it so that it can continue to exist only as mother of 
vinegar, and consequently the process of the formation of 
vinegar will be considerably retarded. Under conditions 
favorable to the development of the ferment the reverse is the 
case. The ferment floating upon the fluid consumes nearly 
all the oxygen contained in the layer of air immediately above 
the surface, and thus deprives the animalcules of a condition 
necessary for their existence. A portion of them die and fall 
to the bottom of the vessel, while another portion of them 
escape to the sides of the vessel where they congregate imme- 
diately above the surface of the fluid in such masses as to form 
a whitish ring. These conditions can be readily induced by 
pouring vinegar containing a large number of vinegar eels 
into a flat glass dish and adding a fluid upon which vinegar 
ferment has been artificially cultivated. In a few hours the 


ferment has spread over the entire surface and the animalcules 
form the above-mentioned white ring on the sides of the vessel. 
If by means of blotting paper the veil of ferment be removed 
as fast as it propagates, the animalcules soon spread over the 
entire fluid. 

From the above explanation it is evident that the appearance 
of vinegar eels in large masses threatens danger to the regular 
working. When the animalcules reach the shavings the strug- 
gle for existence between them and the ferment commences, 
and their struggling to dislodge the latter may be the first cause 
of the formation of slimy masses of mother of vinegar upon 
the shavings. Since the vinegar eels consume oxygen, the air 
in the generators becomes thereby less suitable for the nourish- 
ment of the ferment, and consequently the generators will work 
feebly. By accelerating the draught of air in the generators, 
which is generally the first remedy tried, the development of 
the ferment may again become so vigorous that a large portion 
of the vinegar eels are killed, their bodies being found in the 
vinegar running off. The dead vinegar eels remaining in the 
generator, however, finally putrefy and give rise to the pre- 
viously mentioned disagreeable odor. The processes of putre- 
faction being also effected by bacteria capable of decomposing 
nearly all known organic combinations (even small quantities 
of such strongly antiseptic bodies as salicylic and carbolic 
acids), it is evident that vinegar containing vinegar eels, can- 
not possess good keeping qualities and must be subjected to a 
special treatment, which will be referred to later on. 

Several remedies for the suppression of vinegar eels in the 
generators have been proposed, one of them consisting of the 
introduction of vapors of burning sulphur, i. e., sulphurous 
acid. Sulphurous acid, it is true, kills the vinegar eels, but 
at the same time, the vinegar ferment, and if small remnants 
remain, also the newly-introduced ferment. To restore a 
generator thus treated, a large quantity of air must be blown 
through it, which will remove the last traces of sulphurous 
acid. An alcoholic liquid containing much living ferment is 
then poured in. 


The vinegar ferment can for many hours stand the exclusion 
of oxygen without being destroyed, while the vinegar eels die 
in a short time. This circumstance can be utilized for the de- 
struction of the animalcules without recourse to other reme- 
dies. The generator having first been brought into the high- 
est state of activity by pouring in very warm alcoholic liquid 
and opening all the draught-holes, is left to itself for 6 or 8 
hours after closing all the draught-holes. The ferment in a 
short time consumes all the free oxygen in the generators, and 
the vinegar eels die from the want of it. By opening the 
draught-holes and pouring in alcoholic liquid, the normal 
formation of vinegar soon recommences. 

The killing of a large number of vinegar eels in the above 
manner is, however, of considerable danger to the regular 
working of the factory, and the respective generators must be 
watched with special care in order to meet at once any appear- 
ance of putrefaction. It may sometimes succeed to keep up 
the work undisturbed, the killed vinegar eels being gradually 
removed from the generators by the vinegar running off. In 
such critical cases, when the generator may at any moment 
commence to work irregularly, the use of a very small quan- 
tity of salicylic acid as an addition to the alcoholic liquid 
would be advisable. The acid by checking putrefaction would 
prevent the immediate decomposition of the killed vinegar 
eels still present in the generators. 

Should, however, signs of putrefaction appear, energetic 
means should at once be taken to arrest its progress, it being 
in this case best to sulphur the generator. This is effected by 
closing all the draught-holes except one, and introducing into 
the latter the nozzle of the apparatus whose arrangement is 
shown in Fig. 38. 

In a large clay vessel, best glazed inside, stands upon a tripod 
a shallow dish. The cover of the vessel luted air-tight with clay 
is provided with three openings. The opening in the center is 
closed by a well-fitting clay stopper, while glass tubes bent at 
a right angle and with a clear diameter of about J inch are 



cemented in the openings at the side. The tube reaching 
nearly down to the plate is connected by means of a rubber 
hose with a double-acting bellows, while the second tube lead- 
ing directly from the cover is connected with a second clay 
vessel. From the cover of this vessel a pipe leads to, and is 
fitted into, the open draught-hole of the generator. 

For use the apparatus is put together, as shown in the illus- 
tration, and small pieces of sulphur are thrown through the 
central aperture upon the dish. The sulphur is ignited by 
throwing in a lighted sulphur match, and after closing the 
aperture the bellows is put in operation. The product of the 

FIG. 38. 

combustion of the sulphur passes through the tube into the 
generator, and in ascending dissolves the fluid adhering to the 
shavings to sulphurous acid. The addition of sulphur and the 
blowing-in of air are continued until the odor of burning sul- 
phur is clearly perceptible in the upper portion of the genera- 
tor. The second vessel which contains some water serves for 
the condensation of the portion of the sulphur which is not 
consumed, but only volatilized. 

The sulphurous acid kills every living organism in the gen- 
erator, and consequently all the germs of the vinegar ferment 
are also destroyed. 

After allowing the sulphured generator to stand a few hours, 


fresh air alone is forced through it by means of the bellows. 
The air-holes are then opened and the generator allowed to- 
stand a few days for the sulphurous acid to be converted into 
sulphuric acid by the absorption of oxygen. To bring this 
generator again into operation, it is best to introduce at first a 
number of pourings consisting only of vinegar, with a content 
of acetic acid corresponding to that of the original acetification. 
In consequence of the absorption of sulphuric acid by the 
shavings, this vinegar becomes of no value as a commercial 
article, but it can be used for the preparation of alcoholic 

The last traces of unchanged sulphurous acid having in this 
manner been removed from the generator and the greater 
portion of sulphuric acid adhering to the shavings washed out, 
the generator is again acetified, this being best effected by 
pouring in alcoholic liquid just run off from correctly working 

Disturbances Due to Vinegar Lice (Vinegar Mites). Unless 
the most scrupulous cleanliness prevails, so-called vinegar lice 
will always be found in the factory. They prefer places kept 
constantly moist, and to which the air has access, for instance, 
the draught-holes and the interior of generators beneath the 
false bottom. As a rule, manufacturers do not pay much at- 
tention to their presence, as they apparently exert no influ- 
ence upon the regular working. That such, however, is not 
the case, will be seen from the following occurrence : Some 
years ago, the proprietor of a vinegar factory in Italy informed 
Dr. Bersch, of Vienna, that millions of small animals had 
appeared in the factory and penetrated into the generators, 
the shavings to a certain height being covered with living 
and dead animals, and by reason of the latter putrefying, 
further operations had become impossible. Every drop of 
vinegar running off from the generators contained one or more 
of the mites. A small bottle half full of vinegar and closed 
air-tight by a cork accompanied the communication. Al- 
though the bottle had been sixty hours in transit, on opening 



it a number of living animals were found, congregated especi- 
ally in the fissures of the cork. On examining them with the 
microscope two forms (male and female?) could be clearly dis- 


tinguished, many being only one-quarter or one-half the size 
of others. Figs. 39 and 40 show the two characteristic forms 

FIG. 40. 

of these animalcules. As far as it was possible to determine 
their zoological position, they belong to the family Sarcoptidw. 


No particulars as to their origin seem to be known, the manu- 
facturer simply stating that they had come from the soil. under 
the supports of the generators and gradually rendered the 
latter ineffective. The generators were sulphured in the 
manner above described, and again put into operation. 

To prevent the vinegar mites from collecting in large masses, 
scrupulous cleanliness must prevail in the factory. Especially 
should the draught-holes be from time to time examined, and, 
if mites be found, thoroughly cleansed with hot water, which 
kills them. The mites might also be prevented from^ pene- 
trating into the interior of the generators by rings of a sticky 
substance (turpentine) around the draught-holes. 

Vinegar- Flies. Though, as far as known, the animals 
known as vinegar-flies create no disturbance in the regular 
working of the factory, they deserve mention because they 
appear wherever a fluid passes into acetic fermentation. In 
wine cellars, not kept thoroughly clean, these insects are fre- 
quently found on the bung-holes of the wine-barrels, and in 
factories in which the manufacture of wine vinegar is carried 
on according to the old system, they often occur in great 

The vinegar-fly (Drosophila funebris, Meig) is at the utmost 
0.11 inch long ; it is especially distinguished by large red eyes 
sitting on both sides of the head and meeting in front. The 
thorax and legs are red ; the abdomen, which is provided with 
six rings, is black, with yellow stripes. The wings are longer 
than the body. The larva is white, has twelve rings, on the 
mouth two black hook-like structures, and on the back part of 
the body four warts, two of which are yellow. In eight days 
the larva is transformed into a yellow chrysalis. 

The collection of these flies in large masses can be readily 
prevented by keeping the factory thoroughly clean and being 
especially careful not to spill any fluid. 




IN the manufacture by the slow process, barrels thoroughly 
cleansed with boiling water and previously saturated with hot 
vinegar are used. The bung-holes are left open or loosely 
covered. Smaller barrels with a capacity of from 15 to 25 
gallons are preferred, and earthenware pots holding only 3 to 

5 gallons are also used, it being claimed that they are espe- 
cially suitable for the preparation of very strong vinegar. The 
barrels are arranged in tiers upon wooden supports in such a 
manner that their contents can be readily withdrawn by means 
of a faucet or a siphon. The heating apparatus may be either 
stoves, a hot-air furnace, or an arrangement similar to that 
employed in heating hot-houses. Due attention must be 
given to the methods of maintaining an equable temperature. 

For the induction of the formation of vinegar, finished 
vinegar should be added to the dilute alcohol. By adding a 
few slices of bread, or beer wort, or a decoction of resins, the 
formation of vinegar can in many cases be accelerated, the 
substances named offering nutriment to the vinegar ferment. 

The mixture of weak alcohol and vinegar is called wash. It 
is prepared from whiskey or alcohol, to which sufficient water 
is added that the mixture shows a content of about 6 per cent, 
of alcohol. To this weak spirit one-quarter or one-half of its 
volume of vinegar is added. Suppose vinegar containing 4J 
per cent, of acetic anhydride is to be made. Theoretically, the 
wash should contain a little over 5 per cent, absolute alcohol, 
but on account of the loss by evaporation of alcohol, a wash of 

6 per cent, must be used. If in making this wash 80 per cent, 
alcohol is employed, then the latter would have to be diluted 
so that every gallon of it becomes 13f\ gallons. In other 
words, to 100 gallons of 80 per cent, alcohol 1,250 gallons of 
water are added, which makes 1,330 gallons of mixture, and 


this, after the addition of 300 gallons of vinegar, becomes 1,630 
gallons of wash. A portion of the water must be taken suffi- 
ciently hot to give a temperature of 90 to 100 F. to the 
wash. The resulting wash is placed in the fermenting barrels 
to fill each one two-thirds full, and the temperature of the 
apartment, observed by thermometers placed in different parts 
of it, must be kept at between 75 and 100 F. At the mini- 
mum temperature less fuel is required, but the time needed 
for acetification is extended, and consequently more barrels 
and a larger apartment are needed to make the same amount 
of vinegar. With the maximum temperature the reverse is 
the case. 

Several days after the addition of the wash acetification be- 
gins, and is indicated by a temperature in the barrels slightly 
above that of the apartment. A piece of stone or slate, which 
is usually laid over the bung-hole of each barrel to prevent too 
great evaporation and consequent cooling, is bedewed with 
moisture, and a pungent acid odor is perceived in the room. 
As long as these indications continue, everything is going on 
well, but every barrel must be examined by itself to at once 
restore activity in any " lazy " one, lest putrefaction or mpuldi- 
ness take place and spread to the neighboring barrels. When 
this misfortune occurs, the bad barrels are at once removed 
from the apartment, their contents thrown away, and the 
barrels scoured well with brushes and water, and placed in the 
sun. After they are dry they may be saturated with hot vine- 
gar and brought into action again. If only " lazy," they are 
excited by withdrawing a portion of their contents, which is 
warmed in glass bottles, and with the addition of a little alco- 
hol and vinegar is restored to the casks. 

Too cool a location or a constant draught of air will some- 
times put a cask out of action. This is remedied by re- 
moval, after acetification is restored, to a warmer location, or 
by covering with a non-conductor, such as heavy paper pasted 
over it. 

After a lapse of time dependent on the temperature which 


is kept somewhat higher towards the end of the operation, 
acetification is complete. Otto gives the time generally re- 
quired as follows : 

With a temperature of Weeks required. 
95 to 100 F. 2 to 4. 

86 to 95 F. 4 to 8. 

72 to 86 F. 8 to 16. 

The close of acetification is indicated by the diminution of 
the strong vinegar smell in the room, by the absence of vapor 
condensing upon the slate covers of the bung-holes, and by 
the temperature of the inside of the barrels becoming equal to 
that of the room. 

As soon as acetification in any one barrel is perfected, the 
vinegar must at once be withdrawn, barreled and removed to 
a cooler place than the vinegar room, in which its tendency 
to spoil in the heated atmosphere is very great. The slimy de- 
posit called " mother of vinegar " is removed, and the vinegar 
with which it is imbued, employed in part for the next aceti- 
fication. If the sediment from each barrel be placed in a cask, 
the clear vinegar may be drawn off after the deposition of the 
mother of vinegar. It is well before barreling the vinegar, to 
allow it to stand for a short time in a cool room in a vessel 
filled with beech shavings, which clarify it. When stored, a 
pint of spirits should be added to each barrel. 

As previously mentioned, the slow process above described 
may be modified in various ways. Thus, instead of bringing 
the fermentation to completion in all of the barrels at about the 
same time, they may be divided into three or four groups, so 
that J or J of the whole quantity of vinegar may be with- 
drawn, and stored at intervals of J to J the time required for 
the acetification of the whole quantity. This modification has 
the advantage of a greater distribution of the work ; necessity 
of a smaller quantity of vinegar stored for sale, and the pres- 
ence of barrels in full action, emitting strongly acetic vapors, 
which is of advantage in keeping up fermentation in barrels 


just going into operation. The disadvantages consist in greater 
need for entering and leaving the vinegar room, involving 
loss of its heat, and requiring in consequence greater attention 
to its fires. In addition to this the heat cannot be increased 
towards the close of acetifi cation, which is useful in shortening 
the time for manufacture. 

Another modication consists in always keeping a large 
quantity of vinegar in the fermenting barrels, and at short 
intervals withdrawing small quantities of vinegar which are 
replaced by fresh wash. This saves time, as acetification is 
more rapid in the presence of large bodies of vinegar. It 
involves loss of heat by a need for too frequently entering the 
vinegar room. It involves also a loss of' interest upon the 
value of the large quantity of vinegar kept in the fermenting 
barrels. The intervals at which vinegar may be withdrawn 
are closer in proportion to the heat of the apartment, which 
bears a ratio to the amount of fuel consumed. 

By this method only -J of the vinegar is removed at one time 
from each barrel ; in other words, at intervals of one to two 
weeks, according to temperature, one gallon of vinegar is with- 
drawn from every 5 gallons in the fermenting barrels, and in its- 
stead a gallon of wash is added. In a large factory, the latter 
process requires a large number of barrels of vinegar to com- 
mence operations. The vinegar must be either purchased or 
made gradually in the fermenting barrels, not withdrawing any 
until the barrels are sufficiently full. The advantage consists 
in a smaller number of fermenting barrels being required than 
by the method first described. Dr. Otto gives the following 
calculation for the number of fermenting barrels required for 
the slow process : 

Suppose that it is required to furnish a barrel of vinegar per 
day, excluding Sundays, which would equal 312 forty-gallon 
barrels per year, the fermenting barrels would have each a ca- 
pacity of J barrel, and since they are not filled with wash, and 
on account of unavoidable loss, four such barrels may be allowed 
to each barrel of vinegar made. What is added to make the 


wash is, of course, not accounted as manufactured vinegar, as 
a like quantity must be added in the subsequent wash. From 
every four fermenting barrels, one barrel of vinegar may be 
sold, and hence 6 barrels of vinegar will require 24 fermenting 
barrels. If the workroom be so heated that the operation is 
completed in four weeks, 24 barrels of vinegar will have to be 
drawn off, to do which 96 fermenting barrels will be required. 
If, however, a lower temperature be maintained in the work- 
room, say to complete the process in 16 weeks, 4 times 96 = 
384 fermenting barrels, will be required. In the latter case 
the expense of fuel is lessened, but that of the fermenting 
barrels is increased. Besides, a larger apartment will be neces- 
sary, which will involve a higher rent and greater expense for 
fuel in heating it. If the process be modified, as described, so 
that a large body of vinegar is always kept in the fermenting 
barrels, their number may, as before stated, be proportionately 

This calculation affords the very best illustration of the 
superiority of the modern quick process, over the old slow 
method. To make one barrel per day by the quick process, a 
small room and two generators are the only requisites. 

Household Manufacture of Vinegar. The following method 
is to be recommended as simple, expedient, and furnishing a 
constant supply of vinegar with scarcely any trouble and at 
trifling cost : 

Procure two barrels, the one for making, the other for stor- 
ing the vinegar, barrels from which good vinegar has just been 
drawn being preferable. The storage barrel is always kept in 
the cellar, and the generating barrel in the house or cellar, ac- 
cording to the season. At the top of one of the heads of the 
storage barrel a small hole is bored for the circulation of air. 
The barrels lie on their side, and each of them is furnished 
with a wooden faucet. Their capacity is, of course, regulated 
by the yearly demand. 

Suppose that the generator, filled to the level of the venti- 
lating hole, contains 10 gallons, the manufacture will then 


be carried on as follows : Seven gallons of vinegar of a good 
quality are placed in the barrel, and three gallons of warm 
alcoholic liquid are added. This alcoholic liquid is made as 
follows: If common 50 per cent, whisky be employed, have a 
small measure of 3 pints and a large one (a bucket) of 3 
gallons. If 86 per cent, alcohol is used, let the small measure 
be for 2 pints. Put a small measureful of spirits in the large 
measure ; fill quickly to the mark with boiling water, and 
pour by means of a funnel into the generator. Every two or 
three weeks, three gallons of vinegar are withdrawn from the 
generator and added to the storage barrel, and three gallons of 
alcoholic liquid are placed in the generating barrel as before. 

Another method of working the casks consists in half filling 
the generator with vinegar, and adding every week so much 
of the alcoholic liquid that it fills the barrel in from 8 to 16 
weeks, according to the season. Half the vinegar is then 
added to the storage cask, and the process then recommenced 
iri the generator. The warmer the season the more rapid 
may be the manufacture. 

Preparation of Vinegar with the Assistance of Platinum Black. 
In considering the theory of the formation of vinegar it was 
mentioned that platinum in a finely divided state possesses the 
property of converting alcohol into acetic acid. This property 
of platinum has been utilized for the purpose of manufacturing 
acetic acid on a large scale. The apparatus used for this pur- 
pose consists of a small glass house, provided in the interior 
with a number of compartments. The shelves forming these 
compartments support a number of porcelain capsules. The 
alcohol to be acetified is poured into these capsules, in each of 
which is placed a tripod, also of porcelain, supporting a watch- 
glass containing platinum black or spongy platinum. In the 
roof and at the bottom of the apparatus are ventilators, so con- 
structed as to admit of regulating the access of air. By means 
of a small steam-pipe the interior of the house is heated to 79 
F. By this means the alcohol is gently evaporated, and com- 
ing in contact with the platinum black or sponge is acetified. 


So long as the ventilation is maintained, the platinum black 
retains its property of oxidizing the alcohol. With an appa- 
ratus of 52 cubic yards' capacity and with 37 pounds of plati- 
num black, 150 quarts of alcohol can daily be converted into 
pure vinegar. The drawbacks to this process are high prices 
for alcohol, and the large quantity of the very expensive 
platinum required for working on a manufacturing scale. 



THE vinegar running off from the generators is " finished " 
in so far that it contains the quantity of acetic acid obtainable 
from the content of alcohol in the alcoholic liquid, but it be- 
comes a commercial article only by long storing and special 

The odor of freshly prepared vinegar is by no means agree- 
able. It is very pungent and at the same time stupefying, 
the latter property being no doubt due to small quantities of 
aldehyde contained in it, which, however, volatilize or oxidize 
by storing. The odor depends largely on the materials used 
in the manufacture, that of vinegar prepared from an alcoholic 
liquid composed of water and alcohol alone without an addi- 
tion of beer being decidedly the least agreeable. By long 
storing such vinegar acquires a somewhat finer odor, but never 
especially agreeable properties. 

The barrels for storing fresh vinegar should be filled up to 
the bung-holes and closed air-tight, since when air is present 
the ferment in the absence of alcohol consumes acetic acid, 
thus reducing the strength of the vinegar ; and moreover, mold 
ferment might develop. 

The temperature of the vinegar running off from the gener- 
ators being quite high, its volume diminishes on cooling, and 


consequently the barrels when inspected later on will not be 
quite full. When the vinegar is stored in barrels not made 
air-tight by a suitable coating (lacquer, paraffin, etc.), the air 
penetrates through the pores of the wood and a constant re- 
ciprocal action takes place between it and the vinegar. The 
very slow oxidation thus produced exerts a decidedly favorable 
influence upon the odor of the vinegar, the processes thereby 
taking place being somewhat similar to those which cause the 
formation of the bouquet in wine. This similarity extends 
also to the fact that the vinegar bouquet, if it may so be called, 
is the finer the slower the effect of the oxygen, and this can 
be reached by storing the barrels in a warehouse having a 
temperature of from 57 to GO F., or in a cellar. 

It has been sought to improve the odor of vinegar by various 
additions, but that of volatile oils, such as oils of caraway, 
fennel, anise, etc., which has been frequently proposed for the 
purpose, cannot be recommended. These oils, to be sure, give 
a specific, agreeable odor to the vinegar, but an expert can at 
once detect such additions. More suitable for the purpose is 
the use of a very small quantity (a few hundred-thousandths 
of the weight of the vinegar) of potato or grain fusel oil, these 
bodies forming with the corresponding quantity of acetic acid 
the frequently mentioned odoriferous compound ethers. An 
addition of J per cent, of very strong alcohol to the vinegar 
has also a very favorable effect upon the odor of the latter, 
acetic ether being formed in storing. In place of alcohol, 
acetic ether or amyl acetate (pear essence) can be directly 
added, but only in very small quantities and best in alcoholic 
solutions of a determined content, for instance, 50 grammes of 
pear essence to 1 liter of 95 per cent, alcohol. Of this solution 
0.1 liter (= 100 cubic centimeters) contains 5 grammes of pear 
essence, and if added to 100 liters of vinegar, which in round 
numbers weigh 100 kilogrammes, the latter will contain Tooicro 
of pear essence. By proceeding in this manner the correct 
quantity required can be readily determined. Immediately 
after the addition of one of the above-mentioned substances 



its odor is disagreeably prominent, but becomes pleasant by 

After lying for several weeks a muddy sediment forms on the 
deepest place of the barrel. The vinegar can be carefully 
drawn off from this sediment by means of a rubber hose ; or a 
special apparatus, similar to that shown in Fig. 41, is used for 
the purpose. It consists of the glass tube a, which is inserted 
in the tap-hole of the barrel and reaches to the bottom, where 
it is slightly bent 'upwards. In front of the bung-hole this 
tube is provided with a bulb in which is fitted by means of a 
cork a tube, b, bent at a right angle. While the vinegar is 
stored, this tube stands upright as indicated by the dotted 

FIG. 41. 

lines, and is secured to a rubber hose reaching, up to the 
bung-hole. By turning the tube downward, the fluid runs 
out through the tube a, until its level has sunk to the dotted 

Sometimes the vinegar is not rendered perfectly clear by 
storing, and filtering has to be resorted to. Before referring 
to this operation a few words will be said in regard to the 
storing of vinegar. 

The vinegar brought into the storage barrels contains the 
following constituents: Water, acetic acid, alcohol (very 
little), aldehyde (very little), acetic ether, vinegar ferment 
(living and dead), extractive substances (depending on the 


nature of the alcoholic liquid used). Moreover, there are fre- 
quently found alcoholic ferment (from the beer), and vinegar 
eels and vinegar mites, if these animals exist in the factory. 

By filling the storage barrels to the bung-holes and closing 
them air-tight, the vinegar eels and vinegar mites die in a short 
time for want of air, and fall to the bottom. The living vine- 
gar ferment present in the fluid must assume the form in which 
it can for some time exist without free oxygen, i. e., of mother 
of vinegar. When in consequence of the shrinkage in the 
volume of the vinegar by cooling, the air penetrates through 
the pores of the wood, it is first utilized for the conversion of 
the small quantity of aldehyde into acetic acid, and later on 
enables the vinegar ferment to continue to exist upon the sur- 
face and to slowly convert the small quantity of alcohol still 
present into acetic acid. 

If the barrels are not closed absolutely air-tight, the vinegar 
ferment will develop quite vigorously upon the surface, and 
when all the alcohol is consumed attack the acetic acid, so that 
when the vinegar is tested a decrease in the content of acetic 
acid is plainly perceptible. If the finished vinegar still con- 
tains considerable quantities of albuminous substances in solu- 
tion (vinegar from grain, malt, or fruit), or if it contains 
tartaric and malic acids and at the same time only a small per- 
centage of acetic acid, as most fruit vinegars do (seldom more 
than 5 per cent.), Ihe mold ferment readily settles upon the 
vinegar and finally dislodges the vinegar ferment from the 
surface. The acetic acid is, however, very rapidly destroyed 
by the mold ferment, and through a luxuriant growth of the 
latter, which floats upon the surface as a white membranous 
coating, the vinegar may in a few weeks lose one or more per 
cent, of it. This happens so frequently, for instance with fruit- 
vinegar, that the opinion that such vinegar cannot be made to 
keep, is quite general. 

Vinegar which, besides a considerable quantity of extractive 
substances, contains the salts of certain organic acids (malic 
and tartaric acids), for instance, vinegar prepared from apples 


or wine, must be frequently examined, as it readily spoils, and 
may suffer even if kept in barrels constantly filled up to the 
bung. In fluids containing the salts of the above-mentioned 
organic acids a ferment may frequently develop, even when the 
air is excluded, which first decomposes the. tartaric and malic 
acids, and though these acids are present only in a compara- 
tively small quantity, they influence, to a considerable extent, 
the flavor of the vinegar on account of their agreeable acid 
taste. In vinegar in which this ferment has long existed a 
diminution of acidity can be readily detected by the taste, and 
by the direct determination of the acid a decrease in its con- 
tent can be shown which, if calculated as acetic acid, may in 
some cases amount to one per cent. Besides the loss of its 
former agreeable taste, vinegar thus changed acquires a harsh 
tang, due no doubt to the formation of certain products not 
yet known formed by the ferment effecting the destruction of 
the tartaric and rnalic acids. Moreover, wine or fruit-vinegars 
in which this ferment has for a considerable time flourished, 
lose their characteristic agreeable bouquet which may be con- 
sidered the greatest damage. 

In the presence of a large number of vinegar eels their bodies 
may decay and impart to the vinegar a very disagreeable 
putrid odor, even if stored in barrels closed air-tight. 

The advisability of filtering the vinegar before bringing it 
into the storage barrels will be readily understood from the 
above statement. By filtration it is, however, only possible to 
remove the vinegar eels and vinegar mites swimming in the 
fluid and larger flakes of mother of vinegar. The ferments 
and bacteria inducing putrefaction cannot be thus removed, 
so that even filtered vinegar is liable to spoil when stored. 

Heating the Vinegar. In order to destroy all organisms 
which might cause the spoiling of the vinegar, it is recom- 
mended to heat the latter to about 140 F. before running it 
into the storage barrels. A few moments exposure at this 
temperature being sufficient for the purpose, a large volume 
of vinegar can in a short time be heated with the use of a suit- 
able apparatus, such as is shown in Fig. 42. 



In the head of the barrel b is secured a pipe of pure tin with 
very thin walls and a clear diameter of about j- inch. It is 
-coiled in a boiler filled with water, which it enters at e/and 
leaves at h. It then passes into the barrel b, in which it is also 
coiled, and ends outside the barrel at g. At i it expands to a 
bulb in which a thermometer, t, is placed. A vat, a, placed at 
a certain height above the barrel is provided with a wooden 
stop-cock, c, to which is secured a rubber hose, d, which enters 
the barrel b above the bottom. The pipe k, which is secured 
on top of the barrel b, is open on both ends and of sufficient 
length to project above the vat a. 

FIG. 42. 

The boiler is filled with water and placed in an ordinary 
hearth. The vat a is filled with the vinegar to be heated and 
kept constantly supplied. The water being heated to boiling, 
the stop-cock c is opened. The vinegar now runs through d 
into the barrel b, and, after filling it, flows at e into the tin 
coil and in passing through it in the direction of the arrows 
is heated. The thermometer t dipping into the hot vinegar 
indicates the temperature, and the inflow of vinegar is accord- 
ingly regulated by opening or closing the cock c. As shown 
in the illustration, the hot vinegar runs through the coil sur- 


rounded by cold vinegar into the barrel b, whereby it is cooled 
off and the vinegar in the barrel preparatorily heated. The 
pipe k, open on both ends, allows the escape of the gases de- 

In consequence of the albuminous substances becoming in- 
soluble by heating, the vinegar running off at g is, as a rule, 
more turbid than before. It is brought into the storage bar- 
rels, which need, however, not be closed air-tight, the subse- 
quent processes taking place in the vinegar being of a purely 
chemical nature and not caused by organisms. The latter 
have been killed by heating, and, together with all other for- 
eign bodies suspended in the vinegar, gradually fall to the 
bottom of the barrel. If the vinegar after heating is allowed 
to lie for a sufficiently long time, it clarifies completely and 
an be drawn off perfectly bright from the sediment. 

Filtration of Vinegar. The bodies suspended in the vinegar 
and causing its turbidity being very small, it takes some time 
before they settle on the bottom and the fluid becomes entirely 
<?lear. To accelerate clarification the vinegar is filtered. 

Fig. 43 shows a filter suitable for the purpose. It consists 
of a small, strong wooden vat provided with two perforated 
false-bottoms, s and b. Upon the lower false bottom is spread 
a linen cloth and upon it fine sand, which is not attacked by 
acetic acid, or small pieces of charcoal. Upon the smoothed 
surface of the sand is spread a layer of paper pulp f to 1 inch 
deep which is covered with a linen cloth and then placed upon 
the false bottom b, the latter being forced down by means of 
the screw k and the pieces of wood r. The vinegar to be fil- 
tered is in the vat a which is connected with the filtering vat 
by the stop-cock h and the rubber hose s, 8 to 10 feet long. 
By opening the stop-cock h the filter stands under the pres- 
sure of a column of fluid 8 to 10 feet high and the filtered 
vinegar runs off through an aperture in the side of the filter- 
ing vat. By filling the filter below the paper pulp with fine 
sand, the latter retains the greater portion of the solid bodies 
suspended in the vinegar, and it will be a considerable time 



before the pores of the paper pulp become choked up to such 
an extent as to require its renewal. 

Sharp, fine-grained sand should be used for filtering. It 
should be free from iron and sulphur and previous to use 
freed as much as possible from lime and earthy constituents 
by washing in pure water to which some hydrochloric or tar- 
taric acid may be added. Fine white quartz sand is very 
suitable for the purpose. White sea-sand is also highly 
recommended for filtering vinegar, it being claimed that after 

FIG. 43. 

its use for several months not a single vinegar-eel was found 
in the filtered product. When after long use the sand be- 
comes so closely packed that the vinegar does not run off with 
the rapidity desired, the layer of slime that has accumulated 
upon the sand is carefully removed and the sand thoroughly 
washed and dried, when it is again ready for use. 

An arrangement suitable for filtering larger quantities of 
fluid under an increased pressure is shown in Fig. 44. 

It consists of a strong linen bag, 8, about 16 inches in diam- 



FIG. 44. 

eter, and a jute or hemp hose, R, open at both ends and about 
6 inches in diameter. The bag is tied by means of pack-thread 
to a cylindrical piece of wood which is secured to a suitable 
support. The bag is then connected by means of the rubber 
hose K with the reservoir B, which contains the vinegar to be 
filtered, and is placed about 10 to 13 feet above the support 
carrying the bag. The bag is folded so that it can be inserted 
in the hose R, the latter being also secured to the cylindrical 
piece of w r ood. 

By gradually opening the stop-cock on the reservoir the bag 
is filled with vinegar, but being 
enveloped by the hose R cannot 
entirely expand but only so far 
as permitted by the diameter of 
R, so that though its entire 
surface acts as a filter a large 
number of folds are formed, and 
it is thus protected from burst- 
ing, even under the pressure of 
a column of fluid of consider- 
able height. The fluid filter- 
ing through the bag runs down 
on the hose and collects in a 
vessel placed under it. 

At first this filter generally 
does not act entirely satisfac- 
torily, the fluid running off tur- 
bid ; and this continues until 
the pores of the filter have be- 
come sufficiently contracted to 
retain the small bodies sus- 
pended in the fluid. This can, 
however, be remedied by stir- 
ring some charcoal powder into 
the first portion of vinegar to 
be filtered. The charcoal powder adheres to the sides of the 


bag and contracts the pores of the tissue so that the fluid runs 
off entirely clear. 

By subjecting the freshly-prepared vinegar to heating and 
filtering, a commercial article is obtained which is perfectly 
clear and does not spoil by keeping. By storing it, however, 
for some time in barrels it gains considerable in fineness of 
odor and taste. Wine-vinegar, cider-vinegar and fruit-vinegars 
in general should positively be stored for some time, the 
odoriferous bodies which make these varieties so valuable 
developing only by that means. 

Sulphuring of Vinegar. Sulphuring has long been employed 
as the most convenient method for the preservation of wine, 
and, if correctly applied, can also be used for that of vinegar. 
But as sulphurous acid readily dissolves in vinegar, the latter 
must not be brought in direct contact with the gases arising 
from the burning sulphur. 

The sulphuring of vinegar is best executed as follows : The 
barrel intended for the reception of the vinegar is thoroughly 
rinsed and immediately placed in the storeroom. Then place 
a sulphur match consisting of a strip of linen about 6 inches 
long and f to 1 inch broad dipped in melted sulphur into a 
perforated sheet-iron cylinder about 8 inches long and 1 inch 
in diameter, secure this cylinder to a wire, and after igniting 
the sulphur match, lower it from the bung-hole to the center of 
the barrel. The sulphurous acid formed by the combustion 
of the sulphur is at once dissolved by the water adhering to 
the interior of the barrel. A sulphur match of the above size 
suffices for a barrel of 100 to 125 gallons. 

If the sulphured barrel be now immediately filled with vin- 
egar, the sulphurous acid becomes distributed throughout the 
fluid and kills the vinegar ferment as well as all other fer- 
ments present, so that the vinegar cannot undergo any further 
change except it come again in contact with living ferments. 

The sulphurous acid dissolved in the vinegar is after some 
time converted into sulphuric acid and its presence can be 
readily detected. It may, however, be remarked that the 


quantity of sulphuric acid which reaches the vinegar in the 
above manner is exceedingly small, and, moreover, is partially 
fixed to the mineral bases (lime and magnesia) contained in 
the water used in the preparation of the alcoholic liquid. 
Hence a manufacturer who sulphurs his barrels need not fear 
being accused of having adulterated his vinegar by the direct 
addition of sulphuric acid. Sulphured vinegar must be stored 
at least several weeks before it is salable, the odor of sulphur- 
ous acid adhering to it perceptibly, and disappearing only at 
the rate at which the sulphurous acid is converted into sul- 
phuric acid. 

Fining Vinegar. Similar to wine, vinegar can be obtained 
bright by " fining " with isinglass. This method is employed 
by a number of manufacturers though it offers no advantages 
as compared with filtration. The isinglass to be used is pre- 
pared as follows : Cut with a pair of scissors into narrow strips 
J to 1 drachm of isinglass for every 20 gallons, and soak it in 
water in a porcelain dish for 24 hours. The resulting jelly- 
like mass is pressed through a linen cloth. A solution of J to 
| drachms of tannin for every 20 gallons is then added to the 
isinglass and the mass diluted with vinegar. The whole is 
then thrown into the barrel and thoroughly mixed with th& 
contents. The clarified vinegar is finally drawn off from the 

Coloring Vinegar. Vinegar prepared from alcohol is limpid 
as water or only slightly colored. Prior to the general intro- 
duction of the quick process consumers "were accustomed to 
the dark yellow product prepared from wine or beer, and many 
are still prejudiced against slightly colored vinegar, consider- 
ing it weaker. Unfounded as this prejudice is, the manufac- 
turer is nevertheless obliged to recognize it, and to suit the 
public taste, must color his vinegar by artificial means. Car- 
amel or burnt sugar prepared from glucose is a simple and 
perfectly harmless coloring. It is made by melting the glu- 
cose in a shallow iron vessel over a fire, stirring constantly 
with a long-handled spoon. The melted mass soon turns 


brown and rises in the vessel. The conversion into caramel 
being hastened in the presence of alkalies, the addition of a 
small quantity of pulverized carbonate of ammonium about 
If to 2 per cent, of the weight of the glucose used is of ser- 
vice at this stage. The mass is now heated with constant stir- 
ring until it becomes black, runs from the spoon in viscous 
dark brown threads, and a sample dropped upon a cold sur- 
face congeals to a black mass impervious to light except upon 
the edges. The vessel is then lifted from the fire and the con- 
tents poured out upon metal or stone plates. The taste of the 
congealed mass should not be bitter, or at least only slightly 
so. On exposure to the air, the caramel deliquesces to a thick 
black fluid, and, therefore, it should immediately after its 
preparation, be converted with water into a solution of the con- 
sistency of syrup, such concentrated solution keeping better 
than a dilute one which readily molds. Immediately before 
use the solution is diluted with water, and enough of it added 
to the vinegar to give it the desired coloration. Some manu- 
facturers use molasses or dark syrup for coloring vinegar. 



SINCE acetic acid is formed by the oxidation of alcohol, vin- 
egar can, of course, be prepared from every kind of fluid con- 
taining alcohol, such as beer, wine, cider, as well as from the 
juice of sacchariferous fruits which has passed into alcoholic 
fermentation. By allowing grain to germinate, a body to 
which the term diastase is applied is formed, which possesses 
the property of converting starch into fermentable sugar and 
dextrin when brought in contact with it under certain con- 
ditions. Vinegar can, therefore, be prepared from starch 
though in a round-about way by treating the latter with 


grain containing diastase (malt), whereby it is converted into 
maltose and dextrin. The fluid (sweet mash) is compounded 
with yeast, and the sugar and with a correct execution of the 
process the dextrin also is converted into alcohol by vinous 
fermentation. The resulting alcoholic liquid can then be 
used for making vinegar. 

Alcohol or spirits of wine obtained in the above-described 
manner from the starch contained in potatoes or grain being at 
present the chief material used in the manufacture of vinegar, 
the greater portion of the latter brought into commerce might 
actually be designated potato or malt vinegar according to the 
elementary material used. The great progress made in modern 
times in the preparation of malt, brewing of beer, and in the 
distilling industry has been accompanied by a constantly ex- 
tending division of labor. While formerly every brewer and 
distiller prepared his own malt, there are at present numerous 
establishments exclusively engaged in this branch of the 
industry which sell their product to the brewer and distiller. 
The manufacturer of vinegar who did not use materials con- 
taining finished alcohol (beer or wine) had to undertake the 
laborious work of making the malt and preparing and ferment- 
ing the mash in order to obtain an alcoholic liquid which he 
could finally convert into vinegar. With the present im- 
provements in the preparation of malt and the production of 
alcohol, the vinegar manufacturer can work more cheaply by 
buying the alcohol, and the manufacture of so-called malt or 
grain vinegar would pay only where heavy taxes prevent the 
direct use of alcohol. 

Formerly, when, in consequence of defective processes, 
many a brewing or batch of malt spoiled, it was used for mak- 
ing vinegar. But, as a rule, the vinegar obtained was not 
of a fine taste and remained turbid, and besides, the operation 
was frequently interrupted by all sorts of incidents, which 
led to the opinion of malt-vinegar not possessing keeping 

Beer-wort judged by its composition does not seem a suit- 


able material for making vinegar. Besides a certain quan- 
tity of fermentable sugar (maltose), it contains a considerable 
amount of dextrin and other fermentable bodies. For the 
purpose of making vinegar the maltose alone can be consid- 
ered, it being the only fermentable constituent of beer-wort. 
Hence, vinegar prepared from beer-wort always contains a 
considerable quantity of dextrin and extractive substances, 
and, consequently, is of a more thickly fluid nature than 
belongs to vinegar, and clarifies with difficulty. Moreover, 
this drawback exerts a disturbing influence upon the behavior 
of the vinegar when stored, it being frequently changed by 
further processes of fermentation into a slimy fluid, and ac- 
quires an insipid taste and loses a large portion of its content 
of acetic acid. 

Alcoholic mashes containing in consequence of faulty prepa- 
ration a considerable quantity of dextrin show, when used for 
making vinegar, a behavior similar to that of beerwort ; the 
vinegar obtained clarifies with difficulty and does not keep 
well. Fermented whiskey-mashes properly prepared contain, 
however, only very small quantities of dextrin and extractive 
substances, and, when freed by filtration from admixed husks, 
can be used as a material for the manufacture of vinegar and 
yield an entirely normal product. 

According to experience, the process of the formation of 
vinegar proceeds in the most uniform manner by preparing 
the alcoholic liquid from dilute alcohol, and, consequently, in 
a vinegar factory connected with a distillery it would be best 
to dilute ti on-rectified spirits of wine with the required quantity 
of water and add from 10 to 20 per cent, of the weight of the 
alcoholic liquid of fermented mash. The latter containing 
salts and nitrogenous substances suitable for the nourishment 
of the vinegar ferment serves, in this case, as a substitute for 
the beer generally used in vinegar factories for the prepara- 
tion of alcoholic liquid. 

Manufacture of Malt or Grain Vinegar. Under certain local 
conditions the manufacture of vinegat from malt, with or with- 


out an addition of grain, can be profitably carried on in con- 
nection with that of compressed yeast. Such factories for 
evident reasons not being established on an extensive scale, a 
description of the preparation of vinegar in connection with 
that of compressed yeast without the use of expensive machin- 
ery will be given. 

The preparation of the fundamental material, malt, requir- 
ing much labor and knowledge, it will be best for the manu- 
facturer to buy the article already prepared. Malt kiln dried 
at as low a temperature as possible and yielding a light-col- 
ored extract when treated with warm water should be chosen. 
Many malt houses prepare such malt especially for distilling 
purposes. Malt prepared for brewing purposes is after the 
actual kiln-drying heated to a temperature frequently exceed- 
ing 158 F. for the formation of certain aromatic combinations 
and coloring substances which are to impart to the beer a 
specific taste and dark color. Independently of the dark color 
of the vinegar prepared from such malt, it contains a consider- 
able quantity of dextrin, and consequently acquires an insipid 
by-taste, clarifies with difficulty, and is readily subject to in- 
jurious alterations. Malt, as is well known, contains diastase, 
which in mashing with water effects the conversion of the 
starch into maltose and dextrin. By kiln-drying at a very 
high temperature a portion of the diastase is, however, rendered 
ineffective, and in mashing comparatively little maltose but a 
large quantity of dextrin is formed. Mashing, in this case, 
would have to be continued for a long time in order to obtain 
a larger quantity of maltose. 

With the use of but slightly kiln-dried malt, in which the 
efficacy of the diastase has not been injured by a high tem- 
perature, the greatest directly obtainable quantity of maltose 
and the smallest amount of dextrin are procured. The pro- 
portion of maltose to dextrin is in this case as 4 : 1, or in other 
words, the finished mash contains about 80 per cent, of mal- 
tose and 20 per cent, of dextrin. The dextrin cannot be 
directly converted into acetic acid by the vinegar ferment and 


consequently would be found in the finished product. It is, 
however, possible to treat the finished mash in such a manner 
that the total quantity of dextrin contained in it can be con- 
verted into maltose and the latter into alcohol, in this case 
the theoretically calculated yield of vinegar from the malt 
will be nearly approached in practice, arid the product thus ob- 
tained contain only a small quantity of extractive substances 
of the malt which are not decomposed by alcoholic or acetic 

Before entering upon a description of the mashing process, 
the theoretical part in mashing will be briefly discussed. Malt 
contains starch and diastase. By bringing the comminuted 
malt in contact with water of about 131 to 133 F., the starch 
is formed into paste and the diastase passes into solution. By 
the action of the diastase upon the starch, the latter is con- 
verted into maltose and dextrin, the finished mass containing 
80.9 per cent, of maltose and 19.1 of dextrin. For reasons 
given later on, the finished mass is heated for a short time to 
between 140 and 141.8 F., without, however, exceeding this 
temperature, and then cooled off to the degree required for the 
induction of alcoholic fermentation. 

Mash prepared in this manner contains, besides the stated 
quantities of maltose and dextrin, effective diastase, i. e., such 
as possesses the power of liquefying starch. By heating to 
above 158 F. the diastase entirely loses this property. By 
compounding a mash of this nature with yeast, the diastase 
with the simultaneous action of the yeast is able to convert all 
the dextrin present in the fluid into maltose, and consequently 
the total quantity of starch originally present is converted into 
alcohol by this peculiar process, to which the term after-effect 
of the diastase has been applied. 

Unmalted grain being cheaper than malt and the latter 
containing sufficient diastase to convert a very large quantity 
of starch into maltose and dextrin, a mixture of malt and 
unmalted grain (equal parts of both; f grain and J malt, etc.) 
can be used instead of malt alone. The latter is, however, 


preferable for the manufacture of vinegar, it yielding a product 
of a finer taste than unmalted grain. The mode of preparing 
the mash is exactly the same as for the distillation of alcohol, 
and as the necessary information can be obtained from any 
treatise on that subject, only a brief sketch of the operation 
will here be given. 

The malt carefully ground is mixed with cold water to a 
thin paste, which is stirred until all small lumps are dissolved. 
This mixing of the ground malt with water, dougldng in as 
it is called, can be effected with the assistance of a crutch or 
rake, but best in a vat provided with a mechanical stirring 

Doughing-in being finished, water of 140 to 149 F. is per- 
mitted to run in. until the mash shows a temperature of about 
131 to 133 F. During this operation the mash should be 
constantly stirred. The at first thickly fluid mass will soon 
be observed to become thinly fluid by the starch paste being 
converted into soluble bodies. Mashing is finished in 2 to 2J 
hours, and will be the more complete the more accurately the 
temperature is maintained at 131 P to 133 F. The completion 
of the process is recognized by a filtered sample cooled to the 
ordinary temperature remaining colorless after the addition of 
iodine solution. 

The mash having reached this state, sufficient hot water is 
added with constant stirring to raise the temperature to 140 
or 141.8 F. The purpose of this operation is to render all fer- 
ments present in the mash ineffective. Lactic acid ferment and 
frequently also butyric acid ferment always adhere to the malt, 
and, if allowed to develop in the mash, would form lactic and 
butyric acids during fermentation which would be injurious to 
the process of alcoholic fermentation as well as to the proper- 
ties of the vinegar to be manufactured. The mash is now re- 
duced to a temperature of about 57 or 59 F. by bringing it 
into the cooling-back or passing it through a system of refrig- 
erating pipes. When working on a small scale the mash can 
be suitably cooled by allowing cold water to pass through a 
coil placed in a vat containing it. 


The strength of the vinegar to be manufactured depends on 
the concentration of the mash ; mashes showing a saccha- 
rometer statement of 20 per cent, contain after fermentation 
about 9J per cent, of alcohol which yields vinegar of about 8 
per cent.; mashes showing 18 per cent, yield vinegar of about 
7 per cent., so that 1 per cent, of acetic acid in the vinegar 
may be calculated on for about every 2J degrees indicated by 
the saccharometer. 

The mash is now set with yeast, though the latter may be 
added when the mash still shows a temperature of 71. 5 to 
75 F., the yeast having then time to vigorously propagate. 
Mashes prepared from malt alone are uncommonly rich in 
nourishing substances for the yeast, the latter propagating 
abundantly and inducing a very vigorous process of fermenta- 
tion. This can be profitably utilized by combining the manu- 
facture of vinegar and that of compressed yeast, a valuable 
product being thus obtained without any extra expense and 
with but little labor. At a certain stage of the alcoholic fer- 
mentation the yeast comes to the surface of the fluid and can 
be lifted off. By washing the yeast once or twice with cold 
water and then freeing it from the excess of water by pressing, 
compressed yeast is obtained which, with the exception of the 
portion to be used for setting fresh mashes, can be sold. 

Up to the completion of alcoholic fermentation the treatment 
of the mash as can be seen from the preceding description, 
does not essentially differ from that to which mashes for the 
manufacture of alcohol are subjected. If, however, the com- 
pletely fermented " ripe "mash is to be used for making vine- 
gar, it should be subjected to a special treatment, the object of 
which is to prepare a fluid containing no living yeast. 

By filtering the mash through a closely woven linen cloth 
the particles of malt-husks, etc., are retained but not the cells 
of alcoholic ferment which may be present, and which, on ac- 
count of their minuteness, are difficult to separate from the 
fluid by filtration. It is, therefore, best to heat the mash be- 
fore filtration to about 140 F. whereby the ferment is killed, 


and at the same time a certain quantity of albuminous sub- 
stances dissolved in the fluid is rendered insoluble and sepa- 
rated. The heating of the mash is best effected by passing it 
through a coil of tin-pipe placed in a boiler filled with water 
kept constantly boiling. The temperature of the fluid can be 
readily regulated by increasing or decreasing the velocity with 
which it passes through the coil. If the fluid heated to 140 
F. were allowed to cool in the air, a large portion of the alco- 
hol contained in it would be lost by evaporation, and it is there- 
fore allowed, after heating, to pass through a second coil of 
pipe which is surrounded by cold water whereby it is cooled to 
at least 86 F. This fluid is then filtered through a linen bag, 
is being repeatedly poured back into the filter until it runs off 
sufficiently clear. It will not, however, be obtained perfectly 
clear in this manner, the yeast cells being too minute to be re- 
tained by such a filter, but having been killed by heating, their 
presence in the fluid is connected with no disadvantage. 

By mixing the filtered fluid with from 10 to 15 per cent, of 
its volume of vinegar, an alcoholic liquid is obtained which 
can be worked in the usual manner in the quick-process gen- 
erators, and yields an agreeable aromatic vinegar which clari- 
fies rapidly and improves byt storing. 

According to the slow process, the fermented malt-wort is 
run into casks placed in apartments called " stoves," since 
they are heated by stoves or steam to a temperature ranging 
from 70 to 80 F. The casks are arranged in parallel rows, 
resting upon long wooden beams elevated about 18 inches 
from the ground, and having their bungs uppermost while a 
small hole on top of the front head of each causes the circula- 
tion of air. 

A large saving of labor will be effected by connecting ele- 
vated tanks holding the fermented wort with pipes and mov- 
able flexible hose which will allow of the rapid and easy filling 
of the casks. The vinegar produced is siphoned off into in- 
clined troughs, which deliver it to a central underground 
tank, from which it is pumped into the storing tanks. 


Malt vinegar generally contains a great deal of mucilaginous 
matter which settles with difficulty, preventing its keeping, 
while giving nourishment to vinegar eels. It is therefore 
necessary to filter it, and for this purpose it is pumped into 
the refining or rape vessels. These vessels are often filled with 
wood shavings, straw, or spent tanner's wood, but nothing acts 
as well in producing by filtration a clear bright vinegar as the 
stalks and skins of grapes or raisins technically called " rape." 
Where there is power and a large quantity of vinegar is man- 
ufactured, the filtering is effected under a considerable hydro- 
static pressure. The rape is placed in a closed vessel between 
two false perforated bottoms. A circuit of pipes is connected 
at the lower and upper part of the vessel, and by means of a 
pump the vinegar is made to pass again and again through 
the rape. 

The mode of manufacture is frequently effected by " field- 
ing." In this case, as the term implies, the process is con- 
ducted in the open air. The casks rest on small frames 1J 
feet high, being supported by firm pillars of brick-work or 
wood. The operation generally begins in spring and continues 
during the summer. The fermented liquor is run into the 
casks by the bung-holes, the latt^fr being left open in dry, and 
loosely covered with a tile in wet weather. Gradually the 
alcohol of the "gyle," as the fermented liquor is called, be- 
comes oxidized, and acetic acid is produced, of course simul- 
taneously affording vinegar. The latter is then drawn off and 
transferred, to the refining or rape vessels where it passes 
through the process of filtration already described. 

In some factories large quantities of sour ale and beer are 
converted by similar processes into vinegar, but the product is 
much inferior to the vinegar made from malt-wort. The large 
amount of nitrogenous and other extractive substances which 
those liquids contain undergoes a second or putrid fermenta- 
tion after the alcohol has been oxidized into acetic acid, and 
in doing so reacts upon the acid,, leaving a liquid of a dis- 
agreeable odor slightly resembling very stale beer. By the 


addition of sulphuric acid this second fermentation is post- 
poned for some time, but the vinegar has nevertheless a 
nauseous smell which renders it objectionable. 

Vinegar from Sugar-Beets. The juice of the sugar-beet con- 
tains a considerable quantity of cane-sugar and is readily 
brought into alcoholic fermentation, so that seemingly this 
root would form a very suitable material for the manufacture 
of vinegar. Sugar-beets contain on an average 12 percent, 
of cane-sugar, the latter yielding, when completely fermented, 
a fluid containing about 6J per cent, by weight of alcohol ; a 
fluid with this percentage of alcohol yields vinegar with 6 per 
of acetic acid. 

In addition to sugar the juice of the beet-root contains, 
however, a large number of other substances which exert an 
influence upon the course of alcoholic fermentation, and, be- 
sides alcohol, a large quantity of fusel oils is formed, so that 
the alcohol has to be thoroughly rectified before it is fit for 
use. The fermented beet-root juice itself has, however, a dis- 
agreeable taste and odor, and the vinegar prepared from it 
showing similar properties will not be fit for household pur- 
poses until a remedy for these drawbacks is found. Numerous 
experiments made for the purpose of freeing beet-root vinegar 
from the substances which impart to it a disagreeable odor 
and taste have given no favorable results. Filtering through 
charcoal, and even distilling the vinegar and treating the dis- 
tilled product with strongly oxidizing bodies, do not produce 
the desired effect. From these experiments it would seem 
impossible to directly obtain from sugar-beets vinegar fit for 
household use. 

Vinegar from Sugar, Fruits and Berries. By fermenting 
sugar solution with pure yeast and pouring off the clear alco- 
holic fluid, the latter shows a slightly acid reaction (from suc- 
cinic acid), but is not converted into vinegar even if standing 
for several weeks in the most suitable temperature, because 
the vinegar ferment is wanting. By adding, however, an 
excess of yeast, so that it remains partially suspended in the 


fluid, which can be effected by the addition of solution of gum 
or starch paste, the nourishment for the spores of the vinegar 
ferment reaching the fluid from the air is provided and 
acetification takes place. 

Cadet-Gassicourt advises the fermentation together of 124 
parts of sugar, 868 of water, and 80 of yeast, and to filter after 
one month. Or, according to another formula : Sugar 245 
parts, gum 61, water 2145, yeast 20. Allow to ferment at 
68 F. Fermentation begins the same day and is completed 
in 15 days. 

Doebereiner gives the following directions : Dissolve 10 Ibs. 
of sugar in 180 quarts of hot water, add 6 Ibs. of pulverized 
crude tartar (it dissolves only partially), and after .cooling to 
77 F. induce fermentation by 4J quarts of beer yeast. In 
about eight days, when fermentation is finished, add about 15 
quarts of spirits of wine of at least 50 per cent. Tr. or 8 quarts 
of alcohol of 90 per cent. Tr., and bring the mixture into the 
acetifying vessel. This fluid would also be suitable for the 
quick process. 

For making vinegar on a small scale for domestic use, brown 
sugar with water alone, or sugar with raisins, currants, and 
especially ripe gooseberries, may be used. These should be 
mixed in the proportion which would give a strong wine, put 
into a small barrel filled to about three-fourths of its capacity, 
and bunged very loosely. Some yeast should be put in and 
the barrel set in the sun in summer or a little way from the 
fire in winter, and fermentation will soon begin. This should 
be kept up constantly, but moderately, till the taste and smell 
indicate that the vinegar is complete. It should then be 
poured off clear, and bottled carefully. It will keep much 
better, if it is boiled for a minute, cooled, and strained before 

With the exception of apples and pears, the different varie- 
ties of fruit cannot be had in such abundance as that they 
could be used for the manufacture of vinegar on a large scale, 
and hence only a brief description of their utilization for that 
purpose will be given. 


It is characteristic of most of our varieties of fruits, and 
especially of berries, that in proportion to their content of 
sugar they have a much greater content of free acids than 
grapes, and this circumstance must be taken into considera- 
tion, as otherwise wine would be obtained which contains a 
considerable quantity of unfermented sugar. The following 
table shows the average content of sugar and free acid in the 
most common varieties of fruits : 

Free acid calculated 
Sugar. as malic acid. 

Cherries . . ;; . 10.00 

Apples 6.25 to 13.99 0.691 

Pears . . . .... .' . . . . . . 8.78 

Currants 6.40 2.147 

Strawberries. .'..':.. . . . . . . 5.09 to 11.31 ' 1.363 

Gooseberries . . - . ,< 6.93 1.603 

Bilberries.. . . .V.*.; : .V. 5.78 1.341 

Raspberries . . : ". ...... '.. 4.02 1.484 

Blackberries . ....... . . 4.44 1.188 

According to the above table, currants, gooseberries, rasp- 
berries, etc., contain on an average scarcely 6 per cent, ol 
sugar, and consequently their juice, after complete fermenta- 
tion, would give a fluid with about 3 per cent, of alcohol, from 
which vinegar with about 2J per cent, of acetic acid could be 
obtained. Such vinegar being, however, too weak, those ber- 
ries would not seem suitable for the direct preparation of vine- 
gar. Moreover, the complete fermentation of the juice of most 
berries is very difficult, the free acids, among which malic acid 
preponderates, exerting an injurious influence upon the pro- 
gress of fermentation. 

Vinous fluids of an agreeable taste can, however, be pre- 
pared from berries, and from them an aromatic and finely 
flavored vinegar, by decreasing the content of acid in the juice 
and increasing that of sugar. The juice of currants, as seen 
from the above table, contains in round numbers 6 per cent, 
of sugar and 2 per cent, of malic acid. By diluting this juice 
with an equal volume of water a fluid containing 3 per cent. 


of sugar and 1 per cent, of acid is obtained, and the content 
of the former can be increased at will by the direct addition 
of sugar. 

By compounding, for instance, 100 quarts of currant juice 
with 100 quarts of water and adding 34 Ibs. of sugar, the re- 
sulting fluid contains about 20 per cent, of sugar and after 
complete fermentation gives a fluid with about 9.5 per cent, of 
alcohol, which yields vinegar of nearly 9 per cent, strength. 
The taste of this vinegar is, however, stronger and more agree- 
ably acid than that of vinegar from alcohol, it containing be- 
sides acetic acid about 1 per' cent, of malic acid. Moreover, 
vinegar obtained from berries contains a certain quantity of 
extractive substances and odoriferous products of fermentation, 
so that it possesses an agreeable bouquet and thus appears 
more valuable than the ordinary product. 

In many regions bilberries grow in abundance and can be 
bought very cheap. Treated in the above manner, they yield 
an excellent vinegar, possessing, however, a somewhat harsh 
by-taste, due to the tannin contained in the berries. The latter 
can be removed from the fermented fluid before using it for 
the preparation of vinegar, by compounding the latter when 
quite clear with gelatine solution or fresh white of egg, both 
forming insoluble combinations with the tannin, which sepa- 
rates in the form offtakes. 

In regard to the preparation of vinegar from berries, it re- 
mains to be remarked that, after pressing the bruised berries, 
the juice is compounded with water and sugar and at once 
brought into fermentation by the addition of yeast (best fresh 
wine-yeast, or if this be wanting, compressed yeast divided 
in water). Fermentation should take place at quite a high 
temperature, 68 to 72 F. The separated yeast is carefully 
removed from the fermented liquid and the latter stored away 
in barrels kept constantly filled up to the bung, or at once used 
for the preparation of vinegar. By converting fruit-wine into 
vinegar by means of the vinegar ferment floating upon the 
fluid a much finer product is obtained than by the quick 


Peaches as Vinegar Stock. Mr. H. C. Gore * has made ex- 
periments regarding the value of peaches as vinegar stock. 
The conclusions drawn by him from this work are, first, that 
peaches contain sufficient fermentable sugar for use as vinegar 
stock, and, second, that they can be successfully handled by 
machinery already in use for making apple cider and vinegar. 
Other points of interest are as follows : First, but little varia- 
tion was found in the composition of the same variety of 
peaches when obtained from different localities. Second, the 
peach juices analyzed were found to be richer in sugar than 
those which have been previously analyzed by others, but 
they were about 1 per cent lower in sugar than average apple 
juices. They were considerably richer than apples in suc- 
rose and in acid. Third, it was found that the use of pure 
culture yeasts was not necessary to insure rapid alcoholic fer- 
mentation. Fourth, the ciders prepared from peaches were 
considerably poorer in alcohol than apple ciders on Account of 
the fact that peaches contain less total sugars than apples. 
Fifth, the presence of brown rot was found not to inter- 
fere with the alcoholic fermentation of the ground peaches, 
but a large proportion of the sugars was wasted by allowing 
the fruit to rot before fermenting. Sixth, well-flavored vine- 
gars were produced by the use of a small quick-process gener- 
ator. These vinegars were of acceptable quality, though tur- 
bid, and did not possess the distinctive peach flavor. 

Cider Vinegar. The manufacture of cider itself will be de- 
scribed in another portion of this work and, hence, its utiliza- 
tion for the preparation of vinegar will here only be given. 

The preparation of vinegar from good cider is not difficult, 
the process of acetification by means of the vinegar ferment 
floating upon the surface yielding an aromatic product of a 
fine flavor which is nearly of as good a quality as wine vine- 
gar. On account of its content of malic acid, the vinegar is 

* United States Department of Agriculture, Bureau of Chemistry Circular 
No. 51. 


more acid than ordinary vinegar with the same content of 
acetic acid. But in order to produce cider vinegar of the first 
quality one must have good cider ; vinegar made of watered 
cider will be thin and weak. 

The cider extracted by the first pressing of the apples is 
but in rare cases used for making vinegar, the juice obtained 
by subjecting the pomace, with the addition of water or sugar 
solution, to a second and third pressure being as a rule utilized 
for the purpose. The juice thus obtained should be so consti- 
tuted as to yield vinegar containing 4 J to 5 \ per cent, of acetic 
acid. The cider to be converted into vinegar should be as 
clear as possible and, if necessary, filtration over sand or storing 
for some time is advisable. 

The conversion of cider into vinegar is best effected in a 
generator furnished with a tilting trough for the intermittent 
supply of cider. 

After the cider has been extracted and the cheese removed 
from the press, the pomace may also be utilized for making 
vinegar by treating it as follows : The pomace is piled up on 
a platform of suitable construction and allowed to ferment. 
In the course of a few days considerable heat will be devel- 
oped, when a few pailfuls of warm water (not boiling) are 
poured upon the pile, and in the course of twenty-four hours 
the pomace will be in proper condition for grinding. It is 
then run through a grater-mill and relaid upon the press in a 
cheese in tlpe same manner as originally laid in cider making. 
It is then subjected to heavy pressure until the liquid con- 
tained in the cheese is extracted. This liquid may be ex- 
posed in shallow open casks in a warm room, and in a short 
time will be found good vinegar ; or it may be immediately 
passed through a generator. 

Mr. Walter G. Sackett * gives directions for home-made cider 
vinegar as follows : " The sweet cider as it comes from the 

* Bulletin 192, November, 1913. The Agricultural Experiment Station of the 
Colorado Agricultural College. 


press may either be placed at once in barrels, which should 
not be filled more than two-thirds or three-fourths full, or if 
one has suitable wooden tubs or vats, in a clean, cool place ; 
it may be stored there from 12 to 24 hours to permit settling, 
after which it should be transferred to barrels. The bung 
should be left out and a loose stopper of cotton batting in- 
serted in the hole to decrease evaporation and prevent dirt 
from falling in. The barrels should not be tightly stoppered 
until the vinegar contains at least 4 to 5 per cent, of acetic 
acid, at which time they should be filled entirely full and 
securely bunged. Throughout the entire period of vinegar 
making, the casks should be placed on their side and not on 
the end. This gives the cider a larger free surface exposed to 
the air, which is quite essential to rapid vinegar formation. 
It may also be of some advantage in admitting air to bore a 
If inch hole in each end of the barrel along the upper edge. 
If this is done, the holes should be covered with fine gauze 
wire or two thicknesses of cheese-cloth to exclude small 
vinegar flies. 

" A few days after the cider is put into the barrels the char- 
acteristic frothing appears at the bung-hole. To use a com- 
mon expression, 'it is beginning to work.' This indicates 
that the alcoholic fermentation, the first step in the vinegar- 
making process, has begun, and the sugar of the apple juice is 
being converted into alcohol and carbon dioxide gas. To de- 
pend upon the wild yeast of the air to accomplish the fermen- 
tation is too uncertain since many of them are able to convert 
only a small part of the sugar into alcohol, while others act 
so slowly that they are impracticable. Inasmuch as the per- 
centage of acetic acid in the vinegar depenjds directly upon the 
amount of alcohol produced, it is very essential to secure as 
large a yield of alcohol as possible from the sugar present. 
This means converting all of the sugar into alcohol in the 
shortest time possible. The most satisfactory way of doing 
this is to add one cake of compressed yeast, stirred up in a 
little cooled, boiled water, to each five gallons of sweet cider. 


In place of this, one quart of liquid wine yeast, propagated 
from a pure culture, may be used for each thirty gallons of 

" During the alcoholic fermentation, the cider should be 
kept at a temperature of 05 to 80 F. Here is where many 
make the very serious mistake of putting their fresh cider into 
a cool cellar where the fermentation takes place entirely too 
slowly. If the cider is made in the fall, the barrels should be 
left out of doors for a while on the protected, sunny side of a 
building and kept warm, unless a regular vinegar-cellar, arti- 
ficially heated, is at hand. 

" If yeast is added and the proper temperature is maintained, 
the alcoholic fermentation should be completed in six weeks 
to three months in place of seven to ten months as in the old- 
fashioned way. Experiments along this line have shown that 
when yeast is added and a temperature of 70 F. is held, the 
cider at the end of one month contained 7.25 per cent, of alco- 
hol as against .11 per cent, when no yeast was used and the 
temperature was between 45 and 55 F. Cider kept in a 
cellar at 45 to 55 F. with no yeast added required seven 
months to make 6.79 per cent, of alcohol. 

" Temperature, alone, is an important factor as shown by 
an experiment wherein cider to which no yeast was added was 
held for three months at 70 F. and yielded 6.41 per cent, of 

"There is no question but that the time required for com- 
pleting the alcoholic fermentation can be reduced at least one- 
half by adding yeast and by maintaining the proper tempera- 
tures. By hastening this operation, the loss of alcohol by 
evaporation is reduced, and the acetic fermentation can be 
started that much sooner. 

" As soon as alcoholic fermentation is completed draw off 
the clear liquid, being very careful not to disturb the sedi- 
ment in the barrel. Wash out the barrel thoroughly and re- 
place the hard cider. It is believed that removing this sedi- 
ment permits the acetic acid to form somewhat more quickly, 


and furthermore, the sediment may undergo decomposition 
and impart a disagreeable flavor to the cider. Again these 
dregs may harbor living bacteria which either destroy acetic 
acid or interfere with its formation. 

" We are now ready to introduce the acetic acid germs. 
This ma} 7 be carried on in a number of different ways, but 
preferably by means of a pure culture of a desirable organism 
which has been selected because of its ability to produce strong 
acetic acid and impart an agreeable flavor to the vinegar. In 
place of the pure culture starter, one may add two to four 
quarts of good cider vinegar containing more or less ' mother ' 
for each barrel. The introduction of a desirable organism is 
left to chance in this case. A serious objection to the latter 
method is that sometimes one introduces foreign organisms 
with the ' mother' which may prove detrimental to the vine- 
gar. Pure culture * is free from this objection. 

" With the acetic fermentation, as with the alcoholic, the 
higher temperatures favor the changes. Experimental work 
shows that hard cider to which no acetic acid bacteria were 
added other than those that came from the air, and kept at 
65 F., when six months old, contained 7.03 per cent, of acetic 
acid, while that held at 55 F. showed only 3.63 per cent. 

" The addition of some kind of an acetic acid starter, either 
as a pure culture of the acetic organism or as good vinegar, 
hastens the fermentation and reduces appreciably the time 
required for making marketable vinegar. 

" For most satisfactory results we would recommend using 
the pure cultures and holding the vinegar at a temperature of 
65 to 75 F. Under these conditions, salable vinegar can be 
obtained in three to six months in place of two to three years, 
as is often the case. Theoretically, 100 parts- of alcohol should 
give about 130 parts of acetic acid, but in actual practice this 
will probably fall below 120. 

* The pure cultures, both of yeast and acetic acid bacteria, for vinegar making, 
here referred to, can be obtained by addressing The Bacteriological Department, 
Experimental Station, Fort Collins, Colorado. 


" When the acetic acid has reached 4.5 to 5 per cent., fill 
the barrels as full as possible and cork tightly. In this way, 
contact of the air with the vinegar is cut off and the acetic 
acid organisms soon cease their activity. If this is not done 
and the acetic and other bacteria are allowed to develop in- 
definitely, there is apt to be a reverse reaction resulting in a 
partial or complete loss of the acetic acid. Such vinegar is, 
of course, worthless." 



THESE specialties may be divided into two groups : Into 
those with a specific odor, and those with a specific odor and 
taste. As an example for both kinds tarragon vinegar may 
be taken. If it is prepared by simply dissolving in the vine- 
gar the volatile oil of dragon's wort (Artemisia dracunculus) ob- 
tained by distillation with water, the product is simply per- 
fumed vinegar, the odor of the volatile oil being mixed with 
that of the acetic acid, but the taste remains unchanged. If, 
however, the fresh leaves of the plant are macerated with vine- 
gar, not only the volatile oil is dissolved, but also certain ex. 
tractive substances peculiar to this plant, and the taste of the 
vinegar is also changed, the product in this case being aro- 
matized vinegar. 

By dissolving in vinegar rose oil or rose water (perfumed), 
rose vinegar is obtained. By treating raspberries with vinegar 
the latter absorbs not only the odoriferous substances of the 
raspberry, but also the non-odoriferous extractive substances, 
and the product is aromatized vinegar. 

By skillful manipulation every volatile oil can be dissolved 
in vinegar, and consequently as many different varieties of 
perfumed vinegar can be prepared as there are volatile oils. 


In fact, perfumers prepare a number of such varieties which 
contain one or more volatile oils whose odors harmonize and 
are sold as volatile spirit of vinegar, fumigating vinegar, etc. 
Such vinegars can be prepared in various ways, the finest odors 
being, however, obtained by distilling the fresh parts of the 
plants with water and mixing the distillate, which actually 
represents a solution of the volatile oil in water, with strong 
vinegar. The finest rose vinegar, orange blossom vinegar, 
etc., are prepared in this manner. 

For this rather tedious process of preparing perfumed vine- 
gar, the one in which freshly prepared volatile oils are used 
may be advantageously substituted. Td be sure the volatile 
oils dissolve only sparingly in vinegar, but sufficiently so to 
impart their characteristic odor to it. By using an excess of 
volatile oil it does not dissolve; but distributes itself in fine 
drops throughout the vinegar, rendering the latter opalescent, 
so that fining with tannin and isinglass is necessary to make 
it bright again. 

This drawback can be avoided by a simple manipulation 
which is based upon the fact that a body dissolving with diffi- 
culty dissolves the more readily the greater surface it offers to 
the solvent. 

Prepare glass-powder as fine as the best wheat flour by heat- 
ing pieces of glass, throwing them into cold water, and pulver- 
izing and elutriating in a mortar. By the sudden cooling the 
glass becomes so brittle that it can be readily converted into a 
fine powder. Bring a suitable quantity of this powder into a 
porcelain dish and drop volatile oil upon it with constant rub- 
bing until it is uniformly moistened. Pour the vinegar to be 
perfumed upon this glass powder and stir gently with the 
pestle. The fluid is then poured into the barrel intended for 
the reception of the perfumed vinegar and a fresh quantity of 
vinegar poured upon the glass-powder, this being continued 
until all the glass-powder has been brought into the barrel by 
stirring and pouring over fresh vinegar. The barrel is then 
entirely filled with vinegar, and after being securely bunged, 


rolled in order to secure a uniform mixture of its contents. 
It is then allowed to rest for a few days for the glass-powder 
to settle. The entirely clear perfumed vinegar is then drawn 
off into bottles, which are to be kept in a dark cool room, the 
odor of the volatile oil being injured by light and heat. 

For the preparation of volatile fumigating or toilet vinegars 
it is best to dissolve the volatile oils in uncolored vinegar pre- 
pared from alcoholic liquid. Where the remaining of a small 
residue after the volatilization of the perfumed vinegar is of 
no importance, pulverized sugar may be substituted for the 
glass-powder, as it acts in the same manner ; the only differ- 
ence is that the glass-powder being an insoluble body falls to 
the bottom of the barrel, while the sugar dissolves together 
with the volatile oil in the vinegar. 

By the above-described process perfumed vinegar with the 
odor of dragoii's-wort, peppermint, anise, rose, etc., etc., may 
be prepared, and by a suitable mixture of those whose odors 
harmonize, a great number of fumigating and toilet vinegars 
may be obtained. 

The preparation of aromatized vinegars by means of the ex- 
tractive substances of plants is very simple. The parts of 
plants to be extracted are placed in a suitable vessel, a barrel 
or large flask, and after pouring vinegar over them and closing 
the vessel, are allowed to rest for a few weeks in a moderately 
warm room. In case glass vessels are used they have to be 
kept in a dark room, light exerting an injurious influence upon 
the odors. The vegetable substances used for aromatizing 
vinegar containing, as a rule, a large quantity of water, strong 
vinegar, with 10 to 11 per cent, acetic acid, should be used. 

Below a few formulas for toilet and table vinegars are given : 


Mohr's Volatile Spirits of Vinegar. Equal parts of acetic acid 
and acetic ether, perfumed with a few drops of oil of cloves. 

Aromatic Vinegar. Concentrated acetic acid 8 ounces, oil of 
lavender 2 drachms, oils of rosemary and cloves each 1 
drachm, oil of camphor 1 ounce. 


Bruise the camphor and dissolve it in the acetic acid, then 
add the perfumes ; after standing for a few days with occa- 
sional agitation it is strained and ready for use. 

Henry's Vinegar. Dried leaves of rosemary, rue, worm- 
wood, sage, mint and lavender flowers each 1 ounce, bruised 
nutmeg, cloves, angelica root and camphor each J ounce, alco- 
hol (rectified) 8 ounces, concentrated acetic acid 32 ounces. 

Macerate the materials for a day in the alcohol ; then add 
the acid and digest for a week longer at a temperature of 
about 59 F. Finally press out the now aromatized vinegar 
.and filter it. 

Vinaigre des Quatre Voleurs. Fresh tops of common worm- 
wood, Roman wormwood, rosemary, sage, mint and rue each 
} ounce, lavender flowers 1 ounce, garlic, calamus aromaticus, 
cinnamon, cloves, and nutmeg each 1 drachm, camphor J 
ounce, alcohol or brandy 1 ounce, strong vinegar 4 pints. 

Digest all the materials, except the camphor and spirit, in 
a closely covered vessel, for a fortnight, at summer heat ; then 
express and filter the vinegar produced and add the camphor 
previously dissolved in the brandy or alcohol. 

Hygienic or Preventive Vinegar. Brandy 1 pint, oils of cloves 
and lavender each 1 drachm, oil of marjoram J drachm, gum 
benzoin 1 ounce. 

Macerate these together for a few hours, then add 2 pints of 
brown vinegar and strain or filter. 

Cosmetic Vinegar. Alcohol 1 quart, gum benzoin 3 ounces, 
concentrated aromatic vinegar 1 ounce, balsam of Peru 1 
ounce, oil of neroli 1 drachm, oil of nutmeg J drachm. 


Anise Vinegar. Convert into a coarse powder anise seed 5 
parts, caraway seed f, fennel and coriander seed each J, pour 
5 parts of alcohol and 45 parts of strong vinegar over the 
powders, close the vessel air-tight and let the whole digest in 
a warm place for 6 to 8 days, shaking frequently. Then strain 
the liquid off, press out the residue, filter the vinegar, and put 
it up in bottles. 


Anchovy Vinegar. Reduce 1 pound of boned anchovies to a 
pulp in a mortar and pass the mass through a hair-sieve. The 
bones and parts which do not pass through the sieve are 
boiled for 15 minutes in a pint of water and strained. To the 
strained liquor add 2J ounces of salt and the same quantity 
of flour together with the pulped anchovies, and allow the 
whole to simmer for 3 or 4 minutes ; as soon as the mixture 
is cold add J pint of strong vinegar. 

Tarragon Vinegar. Pick the young tender leaves of dragon's- 
wort (Artemisia dracunculus) when the first flower-buds ap- 
pear. Bruise the leaves, place them in a suitable vessel, pour 
good wine-vinegar over them, and let the whole stand for a 
few days. Then strain the vinegar through a cloth, filter and 
bottle. The bottles must be filled entirely full, as otherwise 
the vinegar will not keep. 

Compound Tarragon Vinegar. Comminute leaves of dragon's- 
wort 100 parts, common bean leaves 25, leaves of basil and 
marjoram each 12J, bay leaves and orris root each 25, cloves 
3J, cinnamon 6J, and shallots 25. Put all in a suitable ves- 
sel, pour 700 to 750 parts of pure, strong vinegar over it, let 
it stand in a warm place and digest 5 or 6 days, frequently 
agitating it. Then strain the vinegar through linen, press 
out the residue, add 25 parts of alcohol, and filter. Keep the 
vinegar in well-corked bottles in a cool, dark place. 

Effervescing Vinegar. Dissolve 500 parts of loaf sugar in 
5000 parts of water, add lemon juce and rind cut up in the 
proportion of 1 lemon to 1 Ib. of sugar, 1J parts of the best 
cinnamon, and 12 parts of beer yeast thoroughly washed. 
Place the whole in a barrel, and after agitating it thoroughly 
let it ferment at a temperature of 55 to 60 F. When fer- 
mentation has ceased the vinous fluid is strained and mixed 
with 1000 parts of best wine- vinegar, previously boiled up, and 
yeast in the proportion of 1 spoonful to 5 Ibs. of sugar. The 
fluid is then distributed in several earthenware pots and ex- 
posed to a temperature of 77 to 88 F. until it has been con- 
verted into strong vinegar. This, while remaining in the pots, 


is mixed with 200 parts of French brandy and after two days 
bottled in small bottles. To each pound of this vinegar are 
added, f part of crystallized tartaric acid, pulverized, and J 
part of bicarbonate of soda. The bottles, as soon as the re- 
spective portion of the mixture has been added to each, must 
be corked as quickly as possible and then stored in a cool 

Herb Vinegar. Chop fine the leaves of marjoram and thyme 
each 13J parts, common bean leaves 6J, leaves of mint, basil 
and celery each 3 J, and fresh shallots 1 J. Pour 600 or 700 
parts of good vinegar over the herbs and treat in the same 
manner as given for compound tarragon vinegar. 

Pine-apple vinegar. This excellent vinegar soon- loses its 
flavor, and it is therefore best to prepare a small quantity at 
a time and keep in bottles closed air-tight. 

Bruise the slices of pine-apple and pour over them a con- 
siderable quantity of vinegar. Close the vessel air-tight and 
let it stand 12 hours ; then pour off the vinegar and filter. 

Celery Vinegar. Celery seed 4J ozs., vinegar 1 pint. Digest 
14 days ; filter. 

Clove Vinegar. Cloves 3J ozs., vinegar 1 pint. Digest 7 
days and strain. 

Mustard Vinegar. Black mustard seed 2 ozs., vinegar 1 
pint. Digest one week and filter. 

Lovage Vinegar. Lovage root 2 ozs., lovage seed 1 oz., 
vinegar 10 ozs. Digest one week and filter. 

Raspberry Vinegar. For the preparation of this vinegar it 
is best to use the residue remaining after pressing the ripe and 
crushed berries, as it contains sufficent aroma to impart to 
vinegar macerated with it for some time an agreeable odor 
and taste of raspberries. However, the juice may also be 
used, but if the vinegar itself is not very strong it becomes 
thereby too much diluted and consequently weak. 

Crush the fresh berries to a paste and allow the latter to 
stand a few days, stirring it frequently, for the small quantity 
of sugar contained in the berries to ferment. By the alcohol 


thus formed the pectin in the juice is to a great extent sepa- 
rated. The paste is then brought into a small bag and 

The press-cake is crushed, made into paste with vinegar 
and spread out flat, exposed to the air for a few days, being 
frequently stirred. During this time the paste, at first pale 
red, again acquires, in consequence of a process of oxidation, 
a vivid red color. The quantity of vinegar required is then 
poured over the paste. The whole is then allowed to digest 
for a few days, when it is pressed and filtered. The flavor of 
raspberry vinegar is improved by adding 10 drops of acetic 
ether per quart. For 1 pound of pressed residue about 4 to 5 
quarts of strong vinegar are used. 

Preparation of Acetic Ether. Among the numerous combi- 
nations into which. acetic acid enters with other bodies, acetic 
ether is of special value for the vinegar manufacturer, it being 
directly used in the manufacture of vinegar. It is readily 
formed on alcohol coming in contact with acetic acid, and it 
would seem with special ease when the latter is in a nascent 
state. Hence a small quantity of it is found in nearly all red 
wines not prepared by fermentation in closed vats, its pres- 
ence being due to the formation of a small quantity of acetic 
acid from the alcohol, which immediately combines with the 
ethyl oxide or ether. 

In vinegar containing a small quantity of unchanged alco- 
hol some acetic ether formed by the conversion of this alcohol 
into acetic acid is always present, and imparting a very deli- 
cate and agreeable bouquet to the vinegar, it is recommended 
to conduct the production of a fine article so that it contains 
a small quantity of it. 

It is, however, not absolutely necessary to leave a small 
quantity of alcohol in the vinegar, as either acetic ether or al- 
cohol can be directly added to the finished product. But in 
both cases the vinegar has to be stored for several weeks ; in 
the first, for the purpose of harmonizing the odors of acetic 
ether and of acetic- acid, and in the latter, for the formation of 
acetic ether. 


A fluid quite rich in acetic ether and very suitable for im- 
parting bouquet to table vinegar can in a very simple manner 
be prepared by mixing in a flask one volume of highly concen- 
trated acetic acid with 95 or 96 per cent, alcohol, and after clos- 
ing the flask air-tight, allowing the fluid to stand in a warm 
room for several months. The resulting fluid is used as an ad- 
dition to the vinegar whose odor is to be improved. Entirely 
pure acetic ether is best prepared in the following manner : To 
9 parts of concentrated sulphuric acid 3.6 parts of commercial 
absolute alcohol are added by means of a funnel tube which 
reaches to the bottom of the vessel, at the same time keeping 
the liquid well stired. After standing for 24 hours this mix- 
ture is added to 6 parts of sodium acetate which has previously 
been fused and broken in small fragments, and after 12 hours 
the mixture is distilled. Thus 6 parts of pure acetic ether are 
obtained, from which, by rectifying over calcium chloride, all 
traces of water are removed. 

IT O ^ 
Pure acetic ether or ethyl acetate has the composition p** 

and represents a fluid clear as water with an agreeable but 
stupefying odor. Its specific gravity is 0.932 and it boils, at 
165.2 F. On account of its volatility it has to be kept in 
well-stoppered bottles, best in a cool place. 

About 3J to 7 ozs. of acetic ether suffice for the improve- 
ment of the odor of 100 quarts of vinegar. 




Since wine contains between 6 and 14 per cent, of alcohol, 
it evidently furnishes an excellent material for vinegar making. 
Both white and red wines may be used for the purpose, but as 
white wine vinegar is as a rule preferred, the product obtained 
from red wine is generally not salable until it has been decol- 
orized, and the process of decolorizing impairs its flavor and 
aroma. Vinegar may also be made from grapes which are 
unsuitable for drying, shipping or wine making, and this may 
be the most profitable use, in some cases, to which even the 
best grapes can be put. If grapes are used they must of course 
be first made into wine by the usual process. According to 
Bioletti* one ton of grapes of 20 Balling should on the aver- 
age yield 135 gallons of vinegar of 9.8 per cent, acetic acid. 
It may be greater or less than this according as the grapes 
contain more or less sugar. This yield may be diminished by 
imperfect crushing and pressing of the grapes whereby more 
must is left in the pomace. Alcohol may be lost by imperfect 
or improper fermentation in which case the vinegar will be 
weaker. The greatest difference between the theoretical and 
the actual yield is in the change from wine into vinegar. 
This is because one or two percent, of alcohol remains uncon- 
verted in the vinegar, and because during the process there is 
a considerable loss of alcohol and acetic acid by evaporation, 
and by reactions within the liquid which produce other sub- 
stances at the expense of the alcohol and acetic acid. If the 
temperature during acetification is too high, or if the acetic 
bacteria are allowed to act too long, this loss may be much 

* Grape Vinegar. By Frederic T. Bioletti. University of California Publica- 
tions. Bulletin No. 227, 1912. 


By allowing the crushed grapes to ferment on the skins 
before pressing, a somewhat larger volume of wine and there- 
fore of vinegar may be obtained. This may amount to 150 
or 160 gallons of vinegar from a ton of grapes. The vinegar, 
however, will be darker colored and, in the case of red grapes, 
red. This color can be removed, but the decoloration is diffi- 
cult and involves some loss of quality. 

Fermentation for twenty-four hours on the skins will much 
facilitate the extraction of the juice without, except in the 
case of grapes very rich in coloring matter, reddening the juice 
very much. 

The question, what constitutes the superiority of wine vine- 
gar over the ordinary product obtained from alcohol is not 
difficult to answer for those who have an accurate knowledge 
of the constitution of wine. Besides the ordinary (ethyl) alco- 
hol, wine vinegar contains very small quantities of other 
alcohols, for instance, amyl alcohol, which in the same man- 
ner as ethyl alcohol is converted into acetic acid, are changed 
into acids possessing a peculiar odor. Moreover, wine very 
likely contains a series of odoriferous substances which pro- 
duce its peculiar aroma termed bouquet or flower, the cenan- 
thic ether found in every wine forming, so to say, the keynote 
in the harmony of the odoriferous substances constituting the 
bouquet. In the conversion of wine into vinegar these bou- 
quet substances are also changed in such a manner that 
bodies distinguished by a characteristic odor are formed. 
Furthermore, wine contains glycerin, a series of non-volatile 
organic acids, tartaric, malic, succinic acids, etc., and finally 
the so-called extractive substances. What changes these bodies 
undergo is not accurately known, but all of them are very 
likely subject to certain modifications because a smaller quan- 
tity of extractive substances and of non-volatile acids is found 
in the vinegar than in the original wine. The following table 
shows the composition of wine and of the vinegar formed 
from it : 


Wine contains Wine-vinegar contains 

Water, Water, 

Ethyl alcohol, Ethyl alcohol (none or very little) 

Other alcohols, Other alcohols (changed), 

Glycerin, Glycerin (less?) 

Acetic acid, (traces), Acetic acid (much newly formed), 

Tartaric acid, Tartaric acid (less), 

Tartar, Tartar (less), 

Malic acid, Malic acid (less), 

Snccinic acid, Snccinic acid (less), 

Tannin, Tannin (changed), 

(Enanthic ether, (Enanthic ether (changed and unchanged), 

Bouquet substances, Bouquet substances. > 

Extractive substances, Extractive substances I changed, 

Coloring substances Coloring substances J 

Acetic ether and other compound \ newly 
ethers / formed. 

The above comparison shows the thorough modification 
wine undergoes in being converted into vinegar, and that the 
resulting product must have a bouquet or flower having a 
certain connection with that of wine. 

Potable wine can be profitably used for making vinegar 
only in localities where in consequence of a very abundant 
harvest it can be bought at a very low price. The chief sup- 
ply for making vinegar is derived from wines, especially from 
varieties with from 8 to 9 per cent, of alcohol, which have 
deteriorated on account of incorrect treatment in the cellar, and 
consequently have become unsalable as a beverage. 

The term " sick " is generally applied to wines in which 
alterations take place by the activity of a certain ferment which, 
when progressed to a certain degree, renders the wine unfit for 
a beverage. " Turning sour " is, for instance, a sickness fre- 
quently occurring in wines poor in alcohol. It manifests itself 
by the development of large masses of a certain ferment which 
quickly destroys the tartaric acid contained in the wine. An- 
other sickness chiefly, occurring in red wines is the so-called 
" turning bitter," the wine, as the term implies, acquiring in a 
short time by the action of a peculiar ferment such a disagree- 
able bitter taste as to render it absolutely unfit for drinking. 


Such wine cannot be used even for vinegar, the latter showing 
the same disagreeably bitter taste. Wine attacked by what is 
called " lactic acid degeneration " can be used for the manufac- 
ture of vinegar, but yields a product of very inferior quality, 
because on the wine being subjected to acetic fermentation the 
lactic acid contained in it is readily converted into butyric acid, 
which possesses a disagreeable rancid odor completely killing 
the pleasant aroma of the bouquet substances. There only re- 
mains as a material actually fit for the preparation of wine- 
vinegar, wine attacked by " acetic degeneration," i. e., wine al- 
ready so much changed by the vinegar ferment as to render 
it unfit for a beverage, and, further, wine which though not 
sick is unsound, showing a taste of mold, of the barrel, etc. 

Wine no longer young and not overly rich in alcohol is 
especially adapted for the nutriment of the vinegar ferment. 
Such wine need only be exposed to a somewhat higher tem- 
perature in order to induce acetic fermentation, which if not 
disturbed in its progress, will finally convert all the alcohol in 
the wine to acetic acid. 

It may be here remarked that every normal wine always con- 
tains, besides the bodies belonging to the series of fatty acids, 
acetic acid, though only about a few ten-thousandths of its 
weight. By storing the wine, the acetic acid does not increase, 
but becomes rather less, it being consumed in the formation of 
compound ethers. Hence, a rapid increase of the acetic acid 
is an indication of the wine being attacked by acetic degenera- 
tion, and if examined with the microscope the ferment charac* 
teristic of acetic fermentation will be found upon its surface. 
Many remedies have been proposed for the cure of acetic de- 
generation, but none of them is of any value except heating 
the wine to about 140 F., whereby the vinegar ferment is 
killed and the further progress of acetic fermentation checked. 
There is, however, absolutely no remedy for the removal or 
neutralization of the acetic acid already present in the wine. 
Heating the wine can only be recommended when the evil has 
been in existence but a short time and the increase of acetic 


acid can be detected only by a very sensitive tongue. Mixing 
wine attacked by acetic degeneration with sound wine in order 
to cover the acid taste is especially unadvisable, since nothing 
can be attained by it except a short delay in the reappearance 
of the evil and the transmission of the infection to the sound 
wine. There are but two ways in which wine attacked by 
acetic degeneration can be in any wise profitably utilized : By 
employing it for the preparation of cognac or converting it into 
wine-vinegar. For the first a distilling apparatus is required, 
and, consequently, cannot be effected by every wine grower, 
while for the latter nothing is necessary but a few vessels read- 
ily procured. 

Young wine attacked by acetic degeneration is also fit for 
nothing else than the preparation of vinegar. On account of 
its large content of albuminous substances it is, however, more 
suitable for the nutriment of the mold ferment than for that 
of the vinegar ferment, and consequently many difficulties oc- 
cur in its conversion into vinegar. These difficulties can, how- 
ever, be largely overcome by introducing large quantities of 
air into such wine and storing for some time in barrels filled 
up to the bung, or heating after the introduction of air to about 
140 F., the separation of the albuminous substances being 
effected by either means, though more rapidly by the latter. 
Before further working the wine has to be filtered to remove 
the albuminous substances rendered insoluble by the treatment 
described, since their presence might give rise to injurious com- 

The so-called after wine obtained from grapes once pressed, 
by a process introduced by Petiot, is a very suitable material 
for making wine vinegar, since after fermentation its composi- 
tion as regards alcohol and extractive substances is very advan- 
tageous. For successfully carrying out the process it is abso- 
lutely necessary to work the marc fresh from the press. 

According to Paul Hassack * there are used for the purpose, 

* Gahrungs-Essig, 1904. 



FIG. 45. 

400 Ibs. fresh marc,* 150 Ibs. glucose and 1000 quarts of 

The glucose is dissolved in about 400 quarts of hot water, 
and after making the whole up to 1000 quarts by the addition 
of 600 quarts of cold water, the solu- 
tion is thoroughly stirred. 

In the meanwhile 400 Ibs. of fresh 
marc are brought into a fermenta- 
tion-vat Fig. 45, and the sugar solu- 
tion at a temperature of 72 to 75 
F. is poured over them. The marc 
should be broken up, and not 
brought into the vat in large lumps. 
Fermentation as a rule commences 
after six hours and as by it the marc 
is forced to the surface, the vat, as 
will be seen from the illustration, is 
furnished with a perforated head B, 
by which the marc is kept below the level of the liquid. 
Fermentation is effected under exclusion of the air, a hydraulic 
ventilating bung g being used, which permits the escape of 
carbonic acid but does not allow air to enter. Fermentation 
is best carried on at a temperature of 68 to 75 F., and the 
fermenting liquid is allowed to remain in the vat till but a 
very weak current of carbonic acid escapes through the venti- 
lating bung (about 6 to 8 days). The young wine is then 
as quickly as possible racked off into barrels for the second or 
after-fermentation. In filling the barrels it is advisable to 
pass the wine through a medium fine hair- sieve. The wine 
should not come in contact with the air any more than can 
possibly be avoided to prevent it from acquiring a darker 
color. The marc is taken from the fermentation-vat and 

* An addition of 1 Ib. or more of crushed quinces per 100 Ibs. of marc imparts 
to the wine and indirectly to the vinegar a very agreeable aroma, and the large 
content of tannin effects a more rapid clearing of the wine. 


An addition of tartaric acid to wine prepared by the above- 
described process is seldom required, and in any case a solu- 
tion of crystallized acid per 100 quarts of the wine when 
racked off for the second fermentation will be sufficient. The 
treatment of the young wine in the cellar is the same as that 
of original wine. The barrels should be kept full up to the 
bung. During the first two weeks of the second fermentation 
it is of advantage to have a ventilating bung in each barrel. 
By taking into consideration the sugar solution that has been 
added to the marc and the sugar contained in the latter itself, 
the wine, when fermentation is finished, will contain about 7 
to 8 per cent, alcohol, 5 to 10 per cent, acid, 0.5 per cent, 
sugar and l.G to 2.3 per cent, extract free from sugar, and 
would yield vinegar with 5.6 to 6. 5 per cent, acetic acid. 

The wine thus obtained when carefully made is dark yellow, 
has an agreeably pure taste, and its odor is aromatic and rich 
in bouquet. When made with the exclusion of air, it is 
durable, easily managed, and clarifies readily. After racking 
off several times into clean, slightly sulphured barrels, it is 
clarified by means of isinglass solution or filtering through a 
linen or paper filter. For fining with isinglass J to J oz. of 
isinglass is sufficient for each 100 gallons of wine. Pound 
the isinglass, cut it into small pieces and soak it for 12 to 24 
hours in fresh water. When taken from the water, squeeze 
it thoroughly and bring it into a vessel together with 1 gallon 
of water in which f oz. of tartaric acid has previously been 
dissolved. The isinglass swells up and is converted into a 
thin jelly-like mass. Dilute this solution with 40 gallons of 
wine, add it to the wine to be fined and stir thoroughly. 
Very young turbid after-wine is not fit for making wine 
vinegar. After-wine for vinegar making should be perfectly 
bright, and at least 4 to 6 months old. 

Before entering upon a description of the various methods 
of making wine vinegar it may be mentioned that a product 
of actually fine quality can only be obtained by a slow pro- 
cess of acetification, wine treated by the quick process yielding 
a product very poor in bouquet. 


The oldest method for making wine vinegar is that to which 
the term " boiling of wine vinegar" (Weinessig Siederei) has 
been applied. A barrel was filled f full with wine to be con- 
verted into vinegar ; a portion of the fluid was then heated to 
boiling and poured back into the barrel. Upon the wine 
thus heated to about 8(3 F., the development of the vinegar 
ferment commenced, and in the course of a few months the 
greater portion of the alcohol was converted into acetic acid. 
The greater portion of the contents of the barrel was then 
drawn off as " ripe wine vinegar," the barrel again filled f 
full with wine, and a portion of this heated. The operation 
was continued in this manner until so much slimy sediment 
had accumulated in the barrel as to render it necessary to 
entirely empty and clean it. This crude process, which, as 
mentioned, was known in Germany as " vinegar boiling," was 
similar to the method formerly in general use in France, and 
which, being still partially practised there in some large wine- 
vinegar factories, for instance in Orleans, may be designated 
as the 

Orleans or old French Process of Making Wine Vinegar. The 
casks, called mothers, which are employed, hold not more 
than 22 gallons, each cask being filled | full. Immediately 
above the level of the fluid a hole is bored in the surface of 
the front end of each cask, this hole as well as the bung-hole 
remaining open ; a stop-cock for the discharge of the fluid is 
placed in the lower part of the cask. The casks are placed in 
rows in the open air, eight, ten. fifteen, or twenty such rows 
constituting what is termed a vinegar field. This so-called 
fielding, which is carried on from spring to fall, may be suitable 
for the southern part of France, but cannot be recommended 
for more northern regions, as the temperature may fall very low 
during the night and rise very high during the day. Exper- 
ience has shown that the propagation and efficacy of the fer- 
ments are very much injured by great variations of tempera- 
ture, and consequently it is decidedly preferable to keep the 
casks in a room the temperature of which can be maintained 


at, at least 68 F. The wine remains in these casks until it is 
converted into vinegar. The latter is then drawn off by means 
of the above-mentioned stop-cock and the casks are again filled 
with wine, etc. The hole in the front end of the cask and the 
bung-hole permit the free access of air to the surface of the 
wine. In other French factories the work is carried on accord- 
ing to a method somewhat different from the one just described. 
Casks having a capacity of up to 100 gallons are used, each 
cask having in the surface of the front end a square aperture, 
which serves to charge the casks with wine as well as for the 
entrance of air. The casks are placed in three rows one above 
another in a room which can be heated. In the beginning of 
the operation a certain quantity of strong vinegar is brought 
into the casks ; about one-fourth of its volume of wine is then 
added, and at intervals of eight days about 10 quarts more. 
When the cask is nearly filled up to the above-mentioned aper- 
ture, the regular process of drawing off vinegar and filling up 
again with wine is commenced. If, for instance, 10 quarts of 
finished vinegar are drawn off, the same quantity of wine is re- 
placed in the cask, and suppose that, according to the manner 
of working, 7, 8, or 10 days are required for the conversion of 
this quantity into vinegar, 10 quarts of vinegar are again drawn 
off after the expiration of that time, this being continued until 
a disturbance occurs. 

In the course of time large masses of slimy matter consist- 
ing of albuminous substances, vinegar ferment vegetating 
below the surface (the so-called mother of vinegar), decayed 
vinegar ferment, etc., form a deposit in the cask, and finally 
accumulate to such an extent as to occupy half the volume of 
the cask, so that the latter has to be emptied and thoroughly 
cleansed. Sometimes the operation has to be interrupted 
much sooner on account of the contents of the cask acquiring 
a disagreeable, putrid odor. The appearance of putrefaction 
is generally due to vinegar eels settling in the interior of the 
cask as a rule, immediately above the level of the fluid 
and developing to such an extent that they form a slimy coat- 


ing on the cask and upon the fluid and suppress the develop- 
ment of the vinegar ferment. These animalcules are de- 
stroyed by being deprived of air, and, hence, when the vinegar 
ferment is brought to vigorous development it withdraws so 
much of the oxygen from the air in the cask that many of 
them die and their bodies sink to the bottom, where they 
sooner or later putrefy. If this putrefying process takes place 
before a cleansing of the casks is considered necessary, it pro- 
gresses to such an extent that the entire contents of the cask 
are converted into a stinking mass which has to be removed 
as quickly as possible. The casks in which such disturbances 
takes place must of course be carefully cleansed by sulphuring 
and washing with boiling water before they are again used. 

The above-described method of making vinegar is full of 
defects. The presence of vinegar in a fluid which itself is to 
be converted into vinegar promotes, to be sure, the formation 
of acetic acid, but is not absolutely necessary, as has been fre- 
quently asserted, for the induction of the process. If such 
were the case, it would evidently be impossible for an alcoholic 
liquid, such as beer or wine to pass on its own account into 
acetic fermentation. The acetification of the casks with boil- 
ing vinegar is irrational, because by heating the vinegar and 
pouring it boiling hot into the casks, not only the vinegar fer- 
ment contained in it, but also that present in the cask or wine, 
is, if not absolutely killed, at least weakened to such an extent 
as to be incapable of converting alcohol into acetic acid. 
That acetic fermentation nevertheless takes place is very likely 
due to the following causes. 

The hot fluid in the cask gradually cools off and is finally 
reduced to a degree of temperature most favorable to the de- 
velopment of the vinegar ferment ; in the same proportion as 
cooling-off takes place the air contracts in the cask and air 
enters from the outside. The latter, however, carries with it 
germs of vinegar ferment which rapidly develop upon the 
fluid when reduced to the proper temperature and cause its 
acetification. The air penetrating into the cask may, how- 


ever, accidentally contain no vinegar ferment, or that con- 
tained in it may not reach the wine ; in such case the wine 
may for weeks remain in the cask without any perceptible 
acetification taking place until the latter finally appears by an 
accidental development of the vinegar ferment. This uncer- 
tainty 'can, however, be readily avoided by the direct cul- 
ture by the vinegar ferment upon the. wine to be acetified. 
Milk, as is well known, turns sour on exposure to the air by 
the milk sugar being converted into lactic acid by the action 
of a ferment frequently occurring in the air, this souring 
taking place in several hours or several days according to the 
temperature 'to which the milk is exposed. It is further a 
well-known fact that the addition of a few drops of sour to 
sweet milk suffices to immediately induce the formation of 
lactic acid in the latter; the ferment of lactic acid fermenta- 
tion being in the true sense of the word sowed upon the milk. 
The ferment develops very rapidly, converts the sugar into 
lactic acid, and in a short time turns the entire quantity of 
milk sour. 

Exactly the same course may be pursued as regards the 
vinegar ferment, it being only necessary to mix the wine with 
a fluid containing living vinegar ferment and place it in a 
sufficiently warm room in order to immediately start the pro- 
cess of the formation of acetic acid. In this case the vinegar 
ferment is sowed upon the wine, or in other words, the wine 
is impregnated with vinegar ferment and intentionally made 
" sick." This method of transmitting ferment to the fluid to 
be fermented has for a long time been in use in the prepara- 
tion of beer and of alcohol. In the brewery the wort, and in 
the distillery, the mash, is brought into fermentation by " set- 
ting" it with yeast, i. e., alcoholic ferment is intentionally 
added. The " setting of wine" with vinegar ferment is the 
only correct method for the preparation of vinegar from wine. 

Pasteur's, or Modern French Method of Preparing Wine Vine- 
gar. Pasteur, as previously mentioned, made exhaustive in- 
vestigations regarding the conditions essential to the life of 



the vinegar ferment, and found that it thrives especially well 
upon a liquid which in addition to water, alcohol and vinegar, 
contains a trace of phosphates. The latter is absolutely neces- 
sary for the propagation of the ferment; if wanting, the fer- 
ment cannot attain vigorous development. Pasteur recom- 
mends a liquid consisting of boiled water 100 per cent., pure 
alcohol 2, crystallized glacial acetic acid 1, phosphate *- . As 
an inorganic combination that contains all the substances re- 
quired for the nutriment and development of the vinegar fer- 
ment, Pasteur gives the following mixture of phosphate : Po- 

FIG. 46. 

tassiurn phosphate 1 part by weight, calcium phosphate 1, 
ammonium phosphate 2, magnesium phosphate 1. 

The liquid prepared according to the above directions is 
exposed to the action of the air at a temperature of 68 to 77 
F. In a short time the surface of the liquid becomes covered 
with the vinegar ferment and by the agency of the latter the 
alcohol present is converted into acetic acid. In the mean- 
while a corresponding quantity of wine has been sterilized by 


heating it to between 158 to 176 F. This process is called 
"Pasteurization" and may be effected in various ways, an 
apparatus for that purpose being shown in Fig. 46.* Upon 
the furnace C sits a vessel F filled with boiling water. In 
this vessel lies a coil of pipe tinned, or better, silvered inside. 
A similar coil also tinned inside lies in the preparatory heater 
and cooler B. The wine to be heated is contained in the vat 
A. It passes through g, /, o, d, to B, and when the latter is 
full, passes through e into the coil in F, where it is heated, the 
temperature of the liquid being indicated by the thermometer 
h. From the coil in F, the pasteurized liquid is cooled by 
passing through a through the coil in B, heating at the same 
time the wine in B, and finally runs off at d. By regulating 
the cocks 6, e, and a, the quantity of wine passing through the 
apparatus can be readily controlled so that the thermometer 
h constantly indicates a temperature between 131 and 140 F. 

Various methods based on the researches of Pasteur have 
been devised, but before entering upon a description of the 
process, it will be necessary to discuss a few undesirable phe- 
nomena which may appear in the conversion of wine into 
vinegar. A thick white skin having the appearance of a ruffle 
may frequently form upon the surface of the wine to be aceti- 
fied, the wine in this case becoming constantly poorer in alco- 
hol, but does not show acidity. Sometimes the previously 
steady increase in the content of acid in the wine suddenly 
ceases and a very rapid decrease in the content of acid takes 
place, the development of the white skin upon the surface 
being also in this case observed. 

The formation of this white coating upon the surface is due 
to the development of mold ferment which in a short time 
propagates to such an extent as to form a thick membranous 
layer, the folds being formed by the superposition of the cells. 
The mold ferment has the property of converting alcohol as 
well as acetic acid into carbonic acid and water, and conse- 

* Gahrungs-Essig by Paul Hassack. 


quently if it settles upon the wine the latter becomes poorer 
in alcohol, and if upon wine containing already a certain 
quantity of acetic acid the latter is also decomposed. The 
mold ferment requires, however, considerable quantities of 
nitrogenous combinations for its vigorous development, and 
therefore, readily settles upon young wine which contains a 
large quantity of albuminous bodies in solution. This fact 
explains the reason why young wine is seldom attacked by 
acetic degeneration, but it readily becomes moldy, and, con- 
sequently cannot be recommended as vinegar material except 
the albuminous substances be first separated by heating the 
wine to 140 F., which is best effected by means of the appa- 
ratus shown in Fig. 42. 

Another serious annoyance in making wine-vinegar is the 
appearance of vinegar eels, which, if not checked in time, may 
lead to the interruption of the entire process. These animal- 
cules are seldom found in factories working with pump or well 
water, but frequently in those using river water, and conse- 
quently their introduction is likely due to such water. In 
case of their appearance in large masses it is best to interrupt 
the process in time in order to prevent the previously men- 
tioned phenomena of putrefaction. The fluid containing the 
vinegar-eels should be drawn off into a thoroughly sulphured 
barrel. The sulphurous acid kills the vinegar eels as well as 
the vinegar ferment, and the filtered fluid, after standing a 
few weeks, whereby the sulphurous acid is converted into sul- 
phuric acid, can again be used as alcoholic liquid. The ves- 
sels in which the vinegar eels have settled must also be 
thoroughly sulphured and then repeatedly washed with water 
before being re- used for making vinegar. 

Throughout the entire factory the greatest cleanliness should 
prevail ; in fact one cannot be too scrupulous in this respect, 
as otherwise by-fermentations readily take place, and another 
plague, the vinegar lice, or more correctly vinegar mites (see 
p. 140) may appear. Should either of these drawbacks happen, 
the workroom, fluids, and vessels should be thoroughly disin- 
fected by means of sulphurous acid. 


As previously mentioned the Orleans method of making 
wine-vinegar cannot be recommended, it being slow and la- 
borious, and besides there is considerable loss of material by 
evaporation and by the formation of large masses of gelatinous 
" mother of vinegar," which depreciates the quality and ne- 
cessitates expensive cleaning of the casks. 

Claudon's Method of Making Wine Vinegar. This is one of 
the methods based on the researches of Pasteur. The appara- 
tus used, Fig. 47 is described by Frederic T. Bioletti * as 
follows: " It consists essentially of a wide, shallow, covered, 
rectangular vat, furnished with numerous openings near the 
top, a by which the entrance of air can be facilitated and 

Fig 47. 

Da a a Da a a .a Da 

regulated. This vat is filled to near the bottom of the air 
vents with a mixture of 4 parts of good new wine and G parts 
of wine which has been pasteurized at 140 F., and when ne- 
cessary filtered. On top of this liquid is floated a light wooden 
grating /, which helps to support the bacterial film and pre- 
vents its breaking and submerging during the various opera- 
tions. When filled, the process is started by placing a small 
quantity of a good bacterial film on top of the liquid which 
soon becomes completely covered when the proper conditions 
of temperature and aeration are maintained. 

"Each acetifying vat is connected with a small measuring 
vat R from which the proper amount of liquid is taken every 

* " Grape Vinegar." University of California Publications College of Agricul- 
ture, Agricultural Experiment Station. Bulletin No. 227, 1912. 


day after a corresponding amount of vinegar has been removed. 
These two vats constitute a unit, several of which, usually six, 
are united in a battery. A factory includes several of these 

" The batteries are fed from a large vat or reservoir, where 
the mixture of wine and vinegar is prepared and stored. The 
vinegar drawn from the batteries runs directly to filters, from 
there to a pasteurizer, and thence to the storage casks. The 
output of these batteries is from two to five times as great 
per square yard of acetifying surface as that of the old methods; 
the cost of operation is considerably less, the loss by evapora- 
tion much reduced, and the quality equal and much more 
under the Control of the manufacturer." 

Rersch's MetJtod of Making Wine- Vinegar. The essential part 
of the entire process is the impregnation of the wine in suitable 
vessels with pure vinegar ferment under conditions suitable 
for the rapid propagation of the ferment. The vessels are so 
arranged that the finished vinegar can be removed and replaced 
by wine to be acetified without disturbing the ferment, one 
being thus enabled to uninterruptedly continue the process of 
the formation of vinegar for a long time, and producing 
vinegar unsurpassed by any other product as regards delicacy 
of taste and odor. According to the above statement, the 
operation includes the culture of the vinegar ferment on a 
small scale and on a large scale, the former for the production 
of pure ferment and the latter for obtaining wine-vinegar. 

The culture of pure vinegar ferment on a small scale is best 
effected by heating wine in a porcelain or glass dish to between 
140 and 150 F., then mixing it with an equal volume of vine- 
gar and pouring the resulting fluid into shallow porcelain plates, 
which are placed in a warm room. In a short time, generally 
in 24 to 30 hours, the veil-like layer of vinegar ferment pre- 
viously described is observed upon the surface of the fluid. If, 
besides the dull spots which are characteristic of pure vinegar 
ferment, spots of pure white color are formed, it is an indica- 
tion of the development of mold ferment. The contents of 


the plates showing this phenomenon have to be boiled and 
then again exposed to the air. 

The wine to be acetified is in large, shallow vats, and is 
brought to fermentation by carefully submerging in it one of 
the above-mentioned plates containing pure vinegar ferment, 
so that the latter is distributed upon the surface ; the plate is 
then withdrawn. The ferment propagates very rapidly, so 
that, in 24 hours, the surface of the wine in the vat is entirely 
covered with a thin veil of it. By keeping the temperature 
of the room in which the vats are placed at about 68 F., the 
acetification of the wine proceeds rapidly, tests repeated at in- 
tervals of 24 hours showing a constant increase in the content 
of acid, until in about 8 days all the wine is converted into 
vinegar when it is drawn off. To avoid the necessity of es- 
pecially impregnating the next quantity of wine the finished 
vinegar is not entirely drawn off, a small quantity, (about f to 
an inch deep), upon the surface of which the vinegar ferment 
floats, being allowed to remain in the vat. By now introduc- 
ing' a fresh lot of wine the vinegar ferment propagates upon 
it and after some time converts it into vinegar. 

With sufficient care the process of the formation of vinegar 
could thus be uninterruptedly carried on for any length of time 
by transferring the vinegar ferment from the finished vinegar 
to the wine, if a cleansing of the vat were not from time to 
time required, on account of the accumulation on the bottom 
of the vessel of decayed vinegar ferment and flakes of albumen 
which have become insoluble. When the vat is to be cleansed 
the last batch of vinegar is to be drawn off as long as it runs off 
clear, and the turbid remainder in the bottom of the vat is 
collected in a special cask, where it is allowed to clarify. The 
vat is then thoroughly cleansed with water, and after filling 
it again with wine, the latter is mixed with pure vinegar 
ferment in the manner already described. 

If, as may happen in very rare cases, mold ferment in the 
form of the above-mentioned white spots appears upon the 
surface besides vinegar ferment, the vat must at once be 


emptied. The process should also be interrupted in case of the 
development of the so-called mother of vinegar. The latter 
appears generally in the form of a soft gelatinous mass sub- 
merged in the fluid, and consists of vinegar ferment, which, 
however, on account of not being in direct contact with the 
air, does not produce acetic acid. The fluid to be acetified 
can be readily separated from the mother of vinegar by filter- 
ing through a close cloth, the mother of vinegar remaining 
upon the latter and finally drying to a whitish mass resemb- 
ling very thin tissue paper. 

From.the above description it will be seen that the rational 
preparation of wine-vinegar is a very simple matter ; but there 
are some difficulties which can, however, be entirely prevented 
or readily overcome. The vinegar ferment is very sensitive 
towards sudden changes in the composition of the fluid upon 
which it lives, as well as towards rapid changes in the tem- 
perature. The sudden change in the composition of the fluid 
is prevented by not drawing off all the finished vinegar, but 
allowing a small portion of it to remain in the vat. The 
fresh supply of wine entering from below then lifts up the re- 
mainder of vinegar, together with the ferment floating upon 
it, and the mixture of both fluids is effected so gradually that 
the change in the composition of the nourishing fluid proceeds 
very slowly. A sudden change in the temperature of the work- 
room can, of course, be readily prevented by proper heating. 

Ripe wines with not much above 6 per cent, of alcohol are 
the best to use, as they yield vinegar with about 5J per cent, 
of acetic acid. Stronger wines with a content of alcohol up to 
10 per cent., are, however, best reduced to about 6 per cent., 
either by water or ordinary vinegar. The strength of the 
latter must be so chosen that the wine-vinegar prepared from 
a mixture of wine and vinegar contains 5J to 6 per cent, of 
acetic acid. The proportions in which vinegar and wine are 
to be mixed for this purpose are found by a simple calculation 
after an accurate determination of the content of alcohol in 
the wine and that of acetic acid in the vinegar. 


The workroom should be so situated as to be protected 
against sudden changes in the temperature and provided with 
a furnace or self- regulating stove. The vessels for the forma- 
tion of vinegar are placed upon suitable supports, and tables 
for holding the plates for the culture of the vinegar ferment 
should be provided. If the size of the room permit, it is ad- 
visable to store in it a few barrels of the material to be worked, 
the fluid thereby gradually acquiring the proper temperature. 

For the formation of the vinegar very shallow vats, best with 
a diameter of 3 J to 5 feet and a depth of 9 to 14 inches, are 

The iron hoops are protected from the action of the acid 
vapors by a coat of asphalt lacquer. The vats are placed in 

FIG. 48. 


the position they are to occupy in the workroom and filled 
with water up to about If to 3} inches from the top, the 
height of the level of the fluid being marked on the inside wall. 
At distances of 3 j inches apart, and 5} in large vats, holes, 
I, Fig. 48 of 0.39 inch diameter are then bored in the wall of 
the vat. One hole, however, is bored in a place about 0.39 
inch deeper than I, and in this hole is fitted a glass tube, g, 
bent at a right angle, under which is placed an ordinary tumb- 
ler. In the bottom of the vat is a tap-hole, Z, closed by a 

If the vat be filled during the operation with wine, the latter 
can only rise until it begins to run off at g. The level of the 
fluid being but little below the holes I, an uniterrupted change 


in the layer of air above the fluid takes place. A wooden 
spigot, //, is fitted in the vat about { to 1 inch above the 
bottom. In the centre of the lid D, which lies loosely upon 
the vat, is an aperture, ; in a second aperture a thermometer, 
r, is inserted, whose bulb dips into the fluid ; and in a third 
aperture is fitted a glass funnel, R, reaching nearly to the bot- 
tom of the vat. 

The operation in such a factor}^ commences with the cul- 
ture of the vinegar ferment. For this purpose as many shal- 
low porcelain plates as there are vats are placed upon the 
table, and wine to the depth of J to f inch is poured in each. 
The room should be heated and kept at a temperature of 86 
F. The manner of the development of the vinegar ferment 
upon the fluid in the plates as well as the precautions which 
have to be taken has already been described. In the com- 
mencement of the operation the culture of the ferment requires 
great attention, it being frequently disturbed by the develop- 
ment of mold ferment, but when the factory is once in proper 
working condition it is readily effected because the air of the 
workroom then contains a large quantity of the ferment, which 
rapidly propagates on coming in contact with a fluid favor- 
able for its development. 

The vats are charged by allowing the fluid to be converted 
into vinegar to run in until it begins to pass out through g. 
The impregnation with ferment is then effected by carefully 
emptying the contents of one of the plates upon the surface of 
the fluid, so that the greater portion remains floating upon it. 
Finally the lid is placed upon the vat and the latter left to 

The ferment soon covers the entire surface of the fluid in 
the vat, and the commencement of the process of oxidation is 
in a short time recognized by the rise of the thermometer dip- 
ping into the fluid. As long as the quantity of alcohol in the 
fluid is comparatively large, the process of the formation of 
acetic acid and the propagation of the ferment takes place 
very rapidly and the thermometer rises constantly ; but with 


an increase in the quantity of acetic acid these processes become 
slower, which is indicated by a fall in the temperature of the 
fluid. The energy of the process must, however, not be al- 
lowed to sink below a certain limit, care being taken to keep 
it up by raising the temperature of the workroom, but not 
higher than is absolutely necessary for the correct working, 
as otherwise there would be a loss of acetic acid or alcohol by 

The most convenient and business-like manner of operating 
a factory arranged as above described is to simultaneously 
charge all the vats with alcoholic liquid, it being then entirely 
in one's power to regulate the heating of the workroom accord- 
ing to the indications of the thermometer dipping into the 
fluid. If, for instance, the operation commences at 77 F., the 
thermometer will soon be observed to rise even if the tempera- 
ture of the workroom remains unchanged. By the oxidation 
of the alcohol sufficient heat is liberated to increase the tem- 
perature of the fluid to above 95 F. It is, however, advisable 
not to allow it to rise above 86 or 90 F., as otherwise the 
losses by evaporation are too great. Hence, if the fluid reaches 
this limit of temperature the heating of the workroom is so 
regulated as to prevent a further rise of the thermometer, and 
a constant temperature is maintained for several days until it 
commences to fall almost simultaneously in all the vats. This 
fall in the temperature, as previously mentioned, is an indica- 
tion of the fluid now containing a comparatively large amount 
of acetic acid and of the slow oxidation of the remaining alco- 
hol. In order to maintain the most favorable conditions for 
the efficacy of the vinegar ferment and to smoothly and rapidly 
complete the process the workroom is now so heated as to 
show a constant temperature of 86 F. as long as the fluid re- 
mains in the vat. 

Side by side with the observation of the statements of the 
thermometer a chemical examination of the fluid has to be 
carried on, this examination gaining in importance the further 
the formation of vinegar progresses. If the content of alcohol 


in the wine to be worked is known, the test is up to a certain 
stage limited to the determination of the acetic acid, but if the 
process has so far advanced that the fluid contains scarcely 1 
per cent, of alcohol, the latter has also to be determined by 
means of the ebullioscope which will be described later on. 
From this moment on the course of the process must be very 
carefully controlled, and interrupted when still 0.15 or at the 
utmost 0.2 per cent, of alcohol is present. This small amount 
of unchanged alcohol exerts a favorable effect upon the quality 
of the vinegar, acetic ether being formed from it and a corre- 
sponding quantity of acetic acid during the time the vinegar 
has to be stored. 

The interruption of the process is best effected by separating 
the fluid from the layer of ferment floating upon it. The stop- 
cock, H, Fig. 48, is opened and left open as long as fluid runs 
out. A layer of vinegar about j to 1 inch deep upon which 
floats the vinegar ferment, remains in the vat, and the stop- 
cock being closed a fresh supply of alcoholic liquid is intro- 
duced through the funnel R until it begins to run out through 
g. The process then commences anew in the manner above 

Theoretically unlimited quantities of wine could be con- 
verted into vinegar by means of such an apparatus, as the 
vinegar ferment which floats upon the fluid that remains in 
the vat, rapidly propagates upon the fresh supply of wine and 
converts it into vinegar. In practice an occasional short in- 
terruption of the process is, however, necessary. During the 
conversion of the wine the greater portion of albuminous sub- 
stances held in solution in it separates as flakes, and, further, 
a portion of the vinegar ferment sinks below the level of the 
fluid and assumes the form of the flaky masses called mother 
of vinegar. The result after a number of operations is a slimy 
sediment, which finally accumulates to such an extent that it 
has to be removed. This is effected, after the finished vinegar 
is drawn off, by opening the tap-hole Z, and removing the 
slimy mass by means of a broom or crutch. The vat is then 


thoroughly washed with water and can be immediately re- 
charged with wine. The slimy mass is best collected in a tall 
vat and allowed to rest. In a few days it separates into two 
layers, the upper one consisting of quite clear vinegar which 
can be used for filling up storage-barrels, and the lower one of 
a thickly-fluid mass from which a certain quantity of vinegar 
can be obtained by filtration. 

The vinegar drawn off from the vats is brought into storage 
barrels which are filled up to the bung and closed air-tight. 
The volume of the vinegar decreasing by cooling, the barrels 
must from time to time be examined and kept filled up to the 
bung-hole. While stored in the barrels the vinegar almost 
completely clarifies^ and by carefully siphoning off the clear 
portion, it can be at once brought into commerce without 
further treatment. When a considerable quantity of slimy 
sediment has collected in the storage-barrels, it is drawn off 
and brought into the above-mentioned clarifying vat,> or is 
clarified by filtration. 

In case of disturbances in the production by the appearance 
of mold ferment or vinegar eels, the process once commenced 
must be carried through as well as possible, and then the en- 
tire operation interrupted for the purpose of thoroughly cleans- 
ing the vessels by washing with boiling water or steaming. 
Under no circumstances should it be attempted to continue 
working with vats infected with mold or vinegar eels, as it 
would only lead to a considerable loss of material, and the 
cleansing of the vessels which would have to be finally done, 
would be more difficult. 

If the vinegar has been made from clear, ripe wine, it will 
generally come quite clear from the apparatus used for its pro- 
duction. Should it be turbid, as may sometimes happen, it 
has to be filtered through a bag or other filter as described on 
p. 156. The turbidity is caused by various substances sepa- 
rated during the formation of the vinegar. Vinegar is much 
more difficult to fine than wine and for this reason alone, only 
clarified, ripe wines should be used for its production. The 


simplest method to clarify the vinegar is to store it for several 
weeks in a cool cellar in casks filled up to the bung. The 
greater portion of the vinegar can then Tbe drawn off perfectly 
clear and only the last portion will require filtering. 

The filtered vinegar is brought into clean casks and stored 
in a cool cellar. However, while thus stored it may some- 
times depreciate in quality and strength by unfavorable con- 
ditions of temperature or handling, such depreciation being 
indicated by a change in the aroma, and the acid taste loses 
its sharpness and shows a peculiar insipidity. The cause of 
this alteration may be attributed to the decomposition of the 
tartaric and malic acids in the vinegar by a ferment. The 
only sure remedy for this and all other alterations is to steri- 
lize the vinegar by heating to 140 F. The apparatus, Fig. 
46, p. 197, for pasteurizing wine, or any other form of pasteur- 
izer may be used for the purpose. The vinegar should come 
out of the pasteurizer cool and the storage-barrels should be 
completely filled, bunged tight and placed in a cool cellar. 

Wine vinegar acquires its special aroma only by being stored 
for several months. French manufacturers store their best 
quality of it for at least one year before offering it for sale and, 
of course, charge a good price. 

When the wine vinegar has acquired a fine taste and aroma 
by storing it should be bottled, this being the most profitable 
way of selling it. As the vinegar should be perfectly bright 
before racking it into bottles it must first be filtered or fined. 
Many manufacturers pasteurize the bottled vinegar. An ap- 
paratus for this purpose * is shown in Fig. 49. It consists of 
an iron receptacle furnished with a cover fitting air-tight, and 
in the interior with a perforated false bottom. The apparatus 
is about 5 feet long, 3 feet 6 inches wide and 1J feet deep. 
Between the perforated false bottom and the actual bottom is 
a pipe-system which is connected by two iron pipes with the 
furnace. The bottles are placed alongside each other upon the 

* German patent No. 17970 granted to Boldt & Vogel, Hamburg. 




perforated false bottom. Before placing them in the appara- 
tus, water is admitted into the latter so as to fill the space 
below the perforated false bottom and cover the latter. Fire 
is then started in the furnace and the water commencing to 
circulate, steam is in a short time evolved in the apparatus. 
The temperature prevailing in the interior is indicated by a 
thermometer on top of the apparatus, and pasteurization can 
thus be carried on to any desired degree. Cooling is effected 
by discontinuing heating and opening the cover. 

Pasteurized wine-vinegar does not spoil if exposed to vary- 

FIG. 49. 

ing temperatures or even if kept in open or improperly closed 
receptacles. It is free from all kinds of ferments and vinegar 
eels, and is not attacked by the spores of the vinegar ferment 
suspended in the air, because the nutriment required for their 
further development has been withdrawn. 

Wine-Vinegar by the Quick Process. Although in making 
wine vinegar of fine quality, the best results are without doubt 
obtained by one of the slow methods above described, a very 
good product can be made from clear wines in one of the gen- 
erators previously described, that furnished with a tilting 


trough being by some manufacturers preferred for the purpose. 
The process is the same as for ordinary vinegar, the principal 
conditions for smooth working being a limited admission of 
air below the perforated false bottom, the use of perfectly clear, 
pasteurized wine, correct measuring of the quantity to be 
poured and its uniform distribution, absolute cleanliness, 
cleansing the perforated head every week or two, according to 
the accumulation of slime, and finally continuous working. 
The last condition continuous working is necessary to pre- 
vent the product from being impaired during the rest at night 
by a decomposition a decrease of its most valuable properties. 

Wine-vinegar made by the quick process has less aroma 
than that prepared by the other method. However, by stor- 
ing it for about three months it gains in quality and aroma 
so that it can scarcely be distinguished from vinegar made by 
the Orleans method. 

Wine Vinegar from Marc The marc left after the wine has 
been pressed consists of the stems, skins and seeds of the grapes 
and contains a not unimportant quantity of must. As, pre- 
viously described, by subjecting the marc with the addition of 
water or sugar solution to fermentation a wine is obtained 
which forms an excellent material for making vinegar. How- 
ever, the marc may also be directly used for the purpose. 

The mass of marc as it comes from the press is broken up 
and put in a pile where it is left to itself until it becomes warm 
and acquires the odor of alcohol and acetic ether. The mass 
is then shoveled into a vat and gently pressed together with a 
shovel. For every 220 Ibs. of marc used, about 10 quarts of 
water are now sprinkled over the mass by means of a watering- 
pot. By the entrance of air while shoveling the pile of marc 
into the vat the action of the vinegar ferment has been accel- 
erated and a considerable quantity of alcohol converted into 
acetic acid, which is indicated by the stronger vinegar odor. 
The water permeating the marc almost completely displaces 
the fluid containing the alcohol and acetic acid, the latter run- 
ning off through an aperture in the bottom of the vat. It is 


collected in a shallow vessel placed in an apartment having 
the ordinary temperature of a living-room, and is allowed to 
rest. The vinegar ferment present in abundance in the fluid 
rises to the surface, where it quickly propagates and converts 
the remainder of the alcohol in the fluid into acetic acid. The 
only difficulty to be overcome in preparing the vinegar ac- 
cording to this method is the appearance of the mold ferment 
upon the surface of the fluid. This can, however, be met by 
removing the growth of this ferment, which is recognized by 
its pure white color, by means of a spoon as soon as it has at- 
tained the thickness of a few millimeters. The vinegar fer- 
ment then commences to propagate and suppresses the further 
growth of the mold ferment. 

If the grapes originally used contained from 18 to 20 per 
cent, of sugar, the vinegar from the marc prepared according 
to this method shows, if not too much water has been used, a 
content of at least 4 or 5 per cent, of acetic acid, and conse- 
quently is immediately fit for table use. By long storing in 
barrels kept filled up to the bung-holes, it acquires a flavor 
resembling that of vinegar prepared from wine. 

On account of the simplipity and the slight expense con- 
nected with it, the above-described process is especially adapted 
for making vinegar for household use. For industrial pur- 
poses it is, however, more advantageous to prepare wine from 
the marc as described on p. 190, and convert the product thus 
obtained into vinegar. 




Determination of Sugar. The sacchariferous materials used 
by the vinegar manufacturer are either whiskey-mashes, malt- 
extracts, or must prepared from wine-marc, apples, etc. The 
determination of sugar contained in these fluids is effected by 
means of various instruments, which are really hydrometers, 
with different names and graduations. The instruments mostly 
used for the determination of sugar in whiskey-mashes and 
malt worts are known as saccharometers, and directly indicate 
the content of sugar in the fluid in per cent. A similar in- 
strument, known as the must-aerometer, serves for the determi- 
nation of the content of sugar in grape-must. According to 
the arrangement of their scales, the must-aerometers indicate 
either direct sugar per cent., 'or degrees ; in the latter case the 
use of special tables accompanying the instrument is required 
for finding the per cent, of sugar corresponding to a certain 
number of degrees. 

No special saccharometer for fruit-must having as yet been 
constructed, the determination of the content of sugar has to 
be effected either by a tedious method unsuitable for practice, 
or, what can be more quickly done, by fermenting a sample 
of the respective must, and after determining the quantity of 
alcohol, ascertaining from it tha content of sugar. 

In place of special saccharometers or must-areometers, an 
ordinary areometer indicating the specific gravity can also be 
used, and the content of sugar corresponding to a certain 
specific gravity found from a reducing table. Tables X to 
XIII at the end of this volume give the content of sugar espe- 
cially for wine-must, but also with sufficient accuracy for apple 
or pear-must, according to the statements of the respective 


Determination of Alcohol. In a factory using commercial 
spirits of wine as the fundamental material for making vine- 
gar, the percentage of absolute alcohol contained in it has to 
be accurately determined in order to enable one to correctly 
calculate, in the manner explained on p. 109, the quantity of 
water required for the preparation of alcoholic liquid of de- 
termined strength. 

For the determination of the content of alcohol in pure 
spirits of wine consisting only of water and alcohol, instru- 
ments called alcoholometers are generally used, they indicating 
the volumes of alcohol contained in 100 volumes of the spirits 
of wine. They are, however, not suited for this purpose when, 
as is frequently the case in a vinegar factory, the spirit of wine 
contains other bodies besides water and alcohol. In this case, 
either the alcohol contained in a sample has to be distilled off, 
and after determining its strength by the alcoholometer, the 
content of alcohol in the total quantity of fluid ascertained by 
calculation, or the determination is effected in a short time 
and with sufficient accuracy for practical purposes by the use 
of a special apparatus. 

Determination of the Alcohol with the Alcoholometer. For the 
vinegar manufacturer the alcoholometer is an important in- 
strument in so far as it serves for quickly ascertaining the de- 
grees of the spirits of wine used. It is best to use an instru- 
ment which is combined with a thermometer, one being thus 
enabled to ascertain the temperature of the fluid simultane- 
ously with reading off the statement of the alcoholometer. 
Tables I to VIII appended to this work give the necessary as- 
sistance for the determination of the actual content of alcohol 
in a fluid whose temperature is above or below the normal 
temperature (59 F.). 

For examining fluids with a very small content of alcohol, 
alcoholometers have been constructed which accurately indi- 
cate at least 0.1 percent. For the manufacture of vinegar, 
four alcoholometers will, as a rule, suffice. They should be 
so selected that one is to be used for fluids with from to 4 


per cent, of alcohol, the second for indicating 4 to 8 per cent., 
the third 8 to 12 per cent., and the fourth 12 to 1C per cent. 
The scale of such alcoholometers comprising only 4 per cent, 
each, is sufficiently large to allow of the easy reading off of 
one-tenth per cent. These instruments serve for the determi- 
nation of the content of alcohol in alcoholic liquid consisting 
only of spirits of wine and water, and are used in examining 
the progress of the formation of vinegar during manufacture. 

Determination of the Alcohol by the Distilling Test The con- 
tent of alcohol in a fluid containing other bodies besides alco- 
hol and water cannot be directly determined by means of the 
alcoholometer, as the statement of the latter would be incor- 
rect on account of the foreign bodies exerting a considerable 
influence upon the specific gravity. Hence, the content of 
alcohol in alcoholic liquid containing a certain quantity of 
acetic acid, or fermented whiskey-mash, beer, wine, etc., can- 
not be ascertained by immersing the alcoholometer in the re- 
spective fluid. In order to determine the content of alcohol 
in such a fluid a determined volume of it is subjected to dis- 
tillation, and the latter continued until it may be supposed 
that all the alcohol present is volatilized and again condensed 
in a suitable cooling apparatus. By diluting the fluid distilled 
over with sufficient water to restore it to the volume of the 
fluid originally used and immersing the alcoholometer the 
content of alcohol is determined. 

A rapid and at the same time accurate execution of all ex- 
aminations being of great importance in practice, a suitable 
apparatus should be used for the distilling test. Such an ap- 
paratus is shown in Fig. 50. It consists of a glass boiling 
flask, K, having a capacity of \ liter in which sits by means 
of a perforated cork a glass tube, E, which is about f inch in 
diameter and 7f inches in length. On top this tube is closed 
by a perforated cork. From the latter a glass tube bent twice 
at a right angle leads to a cooling-coil, which is placed in a 
vessel F, filled with water, and terminates over a graduated 
cylindrical glass vessel G. The uppermost mark on G indi- 



cates the height to which the vessel must be filled to contain 
^ liter = 500 cubic centimeters. Generally vessels are used 
which are so 'graduated that the distance between two marks 
is equal to 2 -V liter or 50 cubic centimeters. The boiling-flask 
stands upon a plate of thin sheet-iron (to prevent bursting 
from an immediate contact with the flame), and together with 
the cooling vessel is screwed to a suitable support. 

In distilling a fluid containing acetic acid the vapors of the 
latter pass over together with those of alcohol and water, and 
consequently, the statement of the alcoholometer would be in- 

FIG. 50. 

correct. This is overcome by placing a few pieces of chalk 
the size of a hazelnut in the tube R. By the vapors coming in 
contact with the chalk the acetic acid is fixed to the lime con- 
tained in it, not a trace reaching the cooling vessel. 

The manner of executing the test with this apparatus is as fol- 
lows : Fill the vessel G to the uppermost mark with the fluid 
whose content of alcohol is to be examined, then pour it into 
the boiling flask K, rinse out G with water, and after pouring 
the rinsing water into K, put the apparatus together as shown 
in the illustration. The contents of K are then heated to boil- 


ing by a spirit or gas flame under the sheet-iron plate upon 
which Crests, the flame being so regulated that the distillate 
flows in drops into G ( . By too strong heating the contents of 
K might foam up and pass into (r, which would necessitate a 
repetition of the experiment with another quantity of fluid. 
Wine, beer, and whiskey-mashes frequently foam up on heat- 
ing, which can, however, be almost completely overcome by the 
addition of a small quantity of tannin solution to the contents 

The heating of the boiling flask is continued until sufficient 
fluid is distilled over into G to fill it from one third to one half 
full, this being a sure indication of all the alcohol present in 
the fluid having passed over. The flame is then removed, the 
vessel G filled to the uppermost mark with distilled water, and 
the fluids intimately mixed by shaking, the mouth of G being 
closed by the hand. The fluid now contained in G consists 
only of water and alcohol, and its volume is equal to that of 
the fluid originally used. By testing the fluid with an alco- 
holometer the content of alcohol found corresponds exactly 
to that possessed by the fluid examined alcoholic liquid, 
beer, fermented whiskey-mash, etc. 

Determination of the Alcohol by Means of the Ebullioscope. 
Many determinations of the content of alcohol in the alcoholic 
fluid having to be made in a well-conducted vinegar factory, 
the above-described distilling test is objectionable on account 
of the time (about twenty minutes) required for its execution. 
Good results are, however, obtained by the use of the ebullios- 
cope and, but a few minutes being required for the test with 
this apparatus, it can be frequently repeated, and thus even a 
more accurate idea of the working of the generators obtained 
than is possible with a single determination by the distilling 
test. The apparatus is very simple, is easily managed, and 
allows, without the use of an sero meter or table, of the direct 
reading-off of the content of alcohol in a fluid containing not 
much over 12 per cent. It is much used in France for the ex- 
amination of wine. The principle of the apparatus is based 


upon the initial boiling point of the fluid to be examined, an 
alcoholic fluid boiling at a lower temperature the more alcohol 
it contains. For instance, wine with 

12 per cent, by volume of alcohol boils at 196.7 F. 
10 " " 198.3 F. 

8 " 201.0 F. 

5 " 203.3 F. 

Fig. 51 shows Vidal-Malligaud's ebullioscope. To a round 
cast-iron stand is screwed a thick-walled brass cup which ex- 
pands somewhat towards the top ; a screw-thread is cut in the 
upper edge. A hollow-brass ring is soldered into the cup near 
its base, the one end of the ring entering it somewhat higher 
than the other. On filling the cup with the fluid to be ex- 
amined this hollow ring also becomes filled. On the one side 
the ring carries a small sheet-iron chimney, and by placing a 
small spirit lamp under this the fluid in the cup is heated, 
this arrangement securing a quick circulation of the fluid 
during heating. Upon the upper edge of the cup a lid is 
screwed, in which a thermometer is inserted air-tight. The 
mercury bulb of the thermometer is on the lower side of the 
lid and, in determining the boiling-point, dips into the fluid. 
The tube of the thermometer is bent at a right angle outside 
the lid, the latter carrying the scale, which is divided not into 
degrees but in per cent, by volume of alcohol. The scale can 
be shifted upon a supporting plate so that it can be fixed at 
any desired place, and, consequently, also so that the ther- 
mometer when dipped into boiling water indicates 0. The 
scale is secured by small screws. Into a second aperture in 
the lid is screwed the cooling-pipe, which is surrounded by a 
wide brass tube for the reception of the cooling water. During 
the determination of the alcohol, which requires about ten 
minutes, the cooling water need not be renewed, the boiling 
point remaining constant during the short time (one or two 
minutes) necessary for making the observation. In heating 
wine, the gases and besides a few light volatile varieties of 



ether, as acetic ether, aldehyde, etbylamine, propylamine, and 
similar combinations escape through the cooling pipe, which 
is open on top, and in heating beer, carbonic acid. For the 
determination of the alcohol in sacchariferous wines, the ebul- 
lioscope is less adapted, nor does it give accurate results with 
the use of dilute wines. 

It has been ascertained by the French Academy that the 

FIG. 51 


statements of the ebullioscope as regards the quantity of alco- 
hol in the wine differ on an average J per cent, from those 
found by accurate distillation. The entire apparatus with the 
exception of the thermometer being of metal, it is not liable to 
breakage. The mercury bulb of the thermomter is compara- 
tively large. For the vinegar manufacturer the ebullioscope is 
a very valuable instrument, as it enables him to accurately 


determine to within % per cent, the content of alcohol in a fluid 
in a shorter time than is possible with any other instrument. 
Its use is especially recommended when the working of one or 
more generators is to be ascertained in a short time, perfectly 
reliable results being obtained in connection with the deter- 
mination of the acid by titration. 

Determination of the Content of Acetic Anhydride in Vinegar 
or Acetometry. The content of acetic acid in vinegar is some- 
times ascertained by a species of hydrometer termed an 
acetometer. The statements of these instruments are, however, 
very unreliable. Vinegar made from dilute alcohol or ripe 
wines in which no great excess of albuminous or other matter 
is present might to a certain limit be tested with sufficient 
accuracy by the acetometer, but vinegars made from malt, 
poor wines, and such liquids as contain an excess of organic 
matters, do not admit of being tested with the required degree 
of accuracy by this method, since the apparent quantity of 
real acetic acid is increased by the presence of foreign bodies 
which add to the density of the liquid. In some cases the 
vinegar is saturated with chalk or milk of lime, the solution 
filtered, and the specific gravity of the acetate of lime liquor 
ascertained, by which a nearer approximation is arrived at 
than by the direct testing of the vinegar, yet implicit reliance 
cannot be placed on either of these two methods. 

The best method of ascertaining the percentage of acetic 
acid in vinegar is by titration or volumetric analysis. For 
the execution of the test a few instruments are required, 
namely, a burette and pipette. The latter is filled by dipping 
the lower end of it into the fluid and sucking on the upper 
end with the mouth until the fluid has ascended nearly to the 
. top. The upper end is then quickly closed with the index 
finger of the right hand. By slightly lifting the finger the 
liquid is then allowed to flow off by drops until its level has 
reached a mark above the convex expansion of the instru- 
ment, when it will contain exactly the number of cubic centi- 
meters indicated opposite to the mark. 


The burette is a cylindrical glass tube open on the top. It 
is graduated, commencing from the top, into whole, one-tenth 
and one-fifth cubic centimeters. The lower end of the tube is 
drawn out to a somewhat distended point so as to allow a 
rubber tube to be drawn over it and securely fastened. In 
the lower end a glass tube drawn out to a fine point is inserted. 
The rubber tube is compressed in the center by a pinch-cock 
or clip, whereby the lower end is closed. The burette is filled 
with fluid from above by means of a small funnel. By a 
quick, strong pressure upon the handle-joint of the clip, some 
liquid is then allowed to flow in a jet into a vessel. By this 
the tube below the clip is filled with liquid and the air con- 
tained in it expelled. By a slight or stronger pressure the 
liquid can, after some experience, be ejected in drops or in a 
stronger jet. The number of cubic centimeters which have 
been allowed to flow out can be readily read off by keeping 
the surface of the fluid in the tube on a level with the eye. 
The test liquor generally used is normal caustic soda solution, 
one cubic centimeter of it corresponding to 0.06 gramme of 
acetic anhydride, and for especially accurate determinations 
decinormal solution, one cubic centimeter of it corresponding 
to 0.006 gramme of acetic anhydride and -^ cubic centimeter 
to 0.0006 gramme. 

For determining the acetic acid the burette is filled to the 
point with soda solution. A corresponding quantity of vinegar 
is then accurately measured off by means of the pipette, and 
after bringing it into a beaker, colored red by the addition of 
one or two drops of litmus tincture and diluted with four or six 
times its quantity of distilled water. The beaker is placed upon 
a white support under the burette and the soda solution in the 
latter ejected in a strong jet by pressing with the right hand 
the handle-joint of the clip, the fluid being constantly agitated 
by gently swinging the beaker with the left. The inflow of 
soda solution is interrupted as soon as a blue coloration on the 
point where it runs in is observed. After thoroughly stirring 
the fluid with a glass rod, the soda solution is again allowed to 



FIG. 52. 

run in, but now drop by drop, the fluid being stirred after the 
addition of each drop. This is continued until the fluid has 
acquired a violet color with a strong reddish shade, and the 
addition of one drop more of soda solution changes the color 
to blue. The appearance of the violet coloration is called the 
neutralizing point, while the change of color from violet to blue 
indicates that the fluid is now neutral, i. e., contains neither 
free acetic acid nor an excess of caustic soda. The determina- 
tion is based upon the coloring substance of litmus appearing 
red in acid, violet in neutral, and blue in alkaline solutions. 

Instead of soda test liquor, a solution of ammonia is some- 
times used to saturate the acid. The solution is prepared by 
adding water to concentrated ammonia till the specific gravity 
is 0.992 ; 1000 grains of this dilute ammonia 
contain one equivalent of ammonia, which is 
capable of saturating one equivalent of acetic 
acid. The application of this test is similar 
to that already described. 

There is some difficulty in preserving the 
dilute ammonia of the same strength, which 
is an objection to its use ; but a uniformity of 
concentration may be insured by introducing 
into the bottle two glass hydrometer bulbs so 
- adjusted that one remains barely touching at 
the bottom, and the other floats just under 
the surface of the liquid as long as the test- 
liquor retains the proper strength. If a part 
of the ammonia volatilizes, the specific gravity 
of the liquor will become proportionately 
greater, and the glass bulbs rise ; the lower one 
higher from the bottom, and the upper one 
partly above the surface. When this happens, 
more strong ammonia is added, till the hydro- 
static drops are properly readjusted. 

Determinations of acetic acid by titration having to be fre- 
quently executed in a vinegar factory, it is advisable to 


use an apparatus which will facilitate the operation. Such 
an apparatus is shown in Fig. 52. Upon a table stands a 
two-liter flask holding the normal soda solution. The flask is 
closed air-tight by a cork provided with three perforations. 
In one of these perforations is inserted a glass tube, A, in 
the lower end of which is a stopper of cotton upon which 
are placed small pieces of burnt lime. On top, the tube is 
closed by a glass tube drawn out to a fine point. Through 
another of these perforations passes a glass tube, R, bent twice 
at a right angle and reaching to the bottom of the flask. The 
portion of this tube outside of the flask, as will be seen in the 
illustration, is somewhat longer than that in the flask, and, 
consequently, the tube forms a siphon. The outside portion 
of this tube is connected by a short rubber tube with the upper 
portion of the burette B. The latter is secured in a vertical 
position by two rods placed on the stand holding the flask. 
Below the burette is connected with a short rubber tube in 
which is inserted a glass-tube drawn out to a fine point. On 
the side near the top of the burette is a small tube bent at a 
right angle, which is connected by a short rubber tube with the 
tube L, the latter reaching only to below the edge of the cork. 
Above and below the burette is closed by the clips Q andQ,. 
For working with the apparatus the flask is filled with nor- 
mal soda solution and the cork inserted air-tight after remov- 
ing from it the tube A, and substituting for it a small glass- 
tube. Now open the upper clip Q and blow vigorously through 
the glass-tube substituted for A, whereby the fluid is forced 
through the tube R into the burette. This being done, cease 
to press upon Q, whereby the latter closes and stops a further 
discharge of the fluid. The tube, A, is then placed in position. 
By now pressing on the clip Q the fluid passes into the burette, 
the air contained in the latter entering the flask through the 
tube L. The burette being emptied by the discharge of the 
fluid through Q lt it .is refilled for another determination of 
acid by simply pressing on Q, and this can be repeated as 
long as the flask contains soda solution. 


In discharging the fluid from the burette by opening Q v air 
from the outside passes into the apparatus through A. In 
doing so it must, however, pass through the lime which fixes 
the carbonic acid contained in it, so that the fluid in the flask 
remains free from carbonic acid even after standing for months. 

The calculation of the quantity of acetic acid present in the 
vinegar examined is made as shown by the following exam- 
ple : 

For 10 cubic centimeters of vinegar were consumed 70 cubic 
centimeters of decinormal soda solution. 

One cubic centimeter of decinormal soda solution being 
equal to 0.006 gramme of acetic acid, hence 70 cubic centi- 
meters=0.42 gramme. ' 

Now, as 10 cubic centimeters contain 0.42 gramme of acetic 
acid, 100 cubic centimeters contain 10 times 0.42 gramme = 
4.2 grammes .of acetic acid ; or the vinegar examined contains 
4.2 per cent, by weight of acetic acid. 

For the determination of the strength of vinegar with suffi- 
cient accuracy for manufacturing and commercial purposes an 
instrument called a vinegar tester is largely used. In the form 
shown in Fig. 53, as described by Frederic T. Bioletti,* the 
acetic acid is determined by the volume of gas given off by 
bicarbonate of soda when treated with a measured volume of 

" The requisite volume of vinegar is measured in the small 
glass tube A and poured into the bottle B. A sufficient 
amount of bicarbonate is then taken with the spoon E and in- 
troduced carefully into the bottle. As soon as the bottle is 
tightly closed with the cork the bicarbonate is shaken gradu- 
ally into the vinegar and immediately carbonic acid gas com- 
mences- to be given off. This gas passing through the rubber 
tube forces the water in the bottle D to rise in the large glass 
tube C. The stronger the vinegar, the more gas will be given 

* Grape Vinegar. University of California Publications, College of Agricul- 
ture Experiment Station. Bulletin No. 227. 



off and the higher the water will rise in the tube G. This 
tube is marked with numbered lines. By reading the num- 
ber of the line nearest the level reached by the water and add- 
ing the estimated height above or below this line, the strength 
of the vinegar is obtained directly in per cent. If the vinegar 
is made from wine 0.5 per cent, must be deducted from the 
observed reading to allow for the tartaric acid of the wine. 

FIG. 53. 

" To insure sufficient accuracy with these instruments cer- 
tain precautions are necessary. The bicarbonate of soda sold 
for cooking purposes is sufficiently pure. In placing it in the 
bottle care should be taken that none gets into the vinegar 
until the bottle is securely corked. There must be no leak in 
the apparatus. This is determined by allowing the column 


of water to remain for a few minutes in the cylinder after 
making a determination. If the column does not fall in this 
time there is no leak of importance. 

"The instruments are adjusted for water of ordinary tem- 
perature. If the water is either very cold or very warm the 
results are inaccurate. The following table shows some of the 
variations due to the use of too warm water." 


TT- True 


of vinegar 


Vme S ar - acidity. 


65 F. 

75 F. 



1 . . 






2 . 

3 . . 

-.'. . . . 1 4.55 






4 . . 

........ 1 7.04 





5 - . 

6 . . 

, 1 8.49 
; . . . ... 10.15 





" No temperature correction is possible as the variations are 
irregular. At 65 F!, as shown by the table, the determina- 
tions agree very closely with the results of more accurate tests. 
There are other sources of error such as the atmospheric pres- 
sure, the pressure of the column of water and the absorption 
of gas by the water, but they are none of them large enough 
to be of any significance to the vinegar maker." 




Detection of Acids. Some unscrupulous manufacturers, in 
order to pass off weak or inferior vinegars, adulterate them 
with mineral acids. Such adulteration is not only a fraud, 
but dangerous to health, and it is necessary to indicate the 
means by which such additions can be detected. 

Sulphuric Acid. Add to a sample of the vinegar a few drops 
of a solution of barium chloride. If the vinegar becomes 
slightly cloudy, the impurities are due to sulphates naturally 
present in the water or in the substances from which the 
vinegar has been made. A heavy white cloud slow in subsid- 
ing will indicate free sulphuric acid in small proportion. If 
the quantity of sulphuric acid is more than a thousandth, the 
sulphate of baryta produces a precipitate and falls rapidly to 
the bottom of the test-glass. 

The presence of free sulphuric acid in vinegar can also be 
determined by coating a porcelain plate with strong sugar 
solution and allowing the latter to dry up. By bringing a few 
drops of the vinegar to be examined upon the plate and placing 
the latter in a moderately warm place, pure vinegar evapo- 
rates, leaving a slightly brownish stain ; vinegar containing 
free sulphuric acid leaves a dark-brown stain which on heating 
the plate turns black. 

The presence of free sulphuric acid in vinegar can be deter- 
mined with still greater sharpness by the following test : Divide 
a piece of starch the size of a grain of wheat in 50 cubic centi- 
meters of vinegar arid reduce the fluid one-half by boiling. To 
the clear fluid cooled to the ordinary temperature add a drop 
of a solution of iodine in spirits of wine. Vinegar containing 
no free sulphuric acid at once acquires a blue coloration ; if 
free sulphuric acid be present, the fluid remains colorless. 


This test is based upon the fact that starch by continued boil- 
ing with sulphuric acid is converted into dextrin and finally 
sugar. Neither of these bodies reacts upon iodine, while a 
very small quantity of starch gives with iodine the charac- 
teristic blue coloration. 

Hydrochloric Acid. Take about 100 cubic centimeters of 
the vinegar to be tested and distil off one-half by means of the 
apparatus Fig. 50, p. 216. Compound the fluid distilled off 
with a few drops of solution of nitrate of silver. In the pres- 
ence of hydrochloric acid a white, caseous precipitate is 
immediately formed, which consists of chloride of silver and 
dissolves in liquid ammonia added in excess. 

Nitric acid is not a frequent adulteration. It is detected 
by saturating with carbonate of sodium or of potassium 
several ounces of vinegar, and evaporating the whole to dry- 
ness. The addition of sulphuric acid and copper turnings 
will cause the evolution of nitrous vapors if nitric acid be 

Lactic Acid. In many varieties of vinegar small quantities 
of lactic acid occur, which can be detected by slowly evaporat- 
ing 100 cubic centimeters of vinegar in a porcelain dish until 
but a few drops remain. If these drops show a very strong 
pure acid taste, the vinegar examined contains lactic acid. The 
presence of lactic acid is, however, not due to an intentional 
addition, but to the material used in the manufacture of the 
vinegar, that prepared from grain, malt or beer always 
containing it. 

Sulphurous Acid. This acid occurs only in vinegar pre- 
pared by fermentation when stored in freshly sulphured bar- 
rels. It may, however, occur in vinegar whose content of 
acetic acid has been increased by the addition of high-grade 
acetic acid prepared from wood-vinegar. The most simple 
method of detecting the presence of sulphurous acid is by 
placing 100 cubic centimeters of the vinegar to be examined 
in a glass distilling apparatus, and connecting the latter by a 
glass-tube with a vessel containing 50 cubic centimeters of 


pure water compounded with about 10 drops of nitric acid. 
After distilling over -jfc of the vinegar the acidulated water is 
heated to boiling for a few minutes and solution of barium 
chloride added. If the vinegar contains sulphurous acid, a 
heavy white precipitate is formed. 

Detection of Metals. The occurrence of metals in vinegar is 
due to the vessels employed in the manufacture or the storage, 
and, hence, the use of metallic utensils, such as stop-cocks, 
pumps, etc., should be avoided as much as possible. Besides 
iron, other metals such as copper, zinc and tin are occasionally 
found in vinegar. y - 

Iron. The presence of this metal imparts a black color to 
the vinegar, which is increased by a few drops of tincture of 
gall-nuts. If the color of vinegar compounded with a few 
drops of solution of tannin is not changed after standing a few 
hours, the vinegar contains no iron, or only so small a quan- 
tity as to be of no importance. 

Copper. While the presence of a small quantity of iron is of 
little importance in hygienic respect, that of copper, zinc, or 
tin is more serious, the combinations of these metals having a 
poisonous effect upon the organism. Copper in vinegar can 
be detected by evaporating to dryness about 1 quart of the 
vinegar to be examined and dissolving the residue in a few 
drops of nitric acid. By compounding a portion of this solu- 
tion with ammonia in excess, the fluid acquires a perceptible 
blue coloration in .the presence of copper. The latter can be 
shown with still greater sharpness by dipping polished iron 
into another portion of the fluid. If the iron becomes coated 
with a perceptible red film (consisting of actual copper), the 
presence of this metal is shown. 

Tin Evaporate to dryness at least 2 or 3 quarts of the 
vinegar ; dissolve the residue in hydrochloric acid, and con- 
duct sulphuretted hydrogen through it until the fluid has 
acquired a strong odor of the latter. If a precipitate is formed, 
it is filtered off, dissolved in strong hydrochloric acid, and the 
solution divided into several portions. Compound one of these 


portions with dilute solution of chloride of gold ; if after some 
time it becomes red and precipitates red flakes, the vinegar 
contains tin. The presence of tin is also indicated if another 
portion of the solution of the precipitate in hydrochloric acid 
does not acquire a blue color after the addition of potassium 
ferrocyanide. The behavior of the fluid towards solution of 
potassium permanganate may serve as a controlling test ; if 
the fluid contains tin, the solution of potassium permanganate 
becomes discolored. 

Determination of the Derivation of a Vinegar. The examina- 
tion of a vinegar as regards the materials used in its prepara- 
tion is generally effected by the- senses of odor and taste. 
There are, however, a number of tests of ready execution which 
assist the judgment of the tongue and nose. 

Vinegar prepared from dilute spirits of wine is colorless or 
only colored slightly yellowish. If such vinegar has a dark 
yellow color resembling that of wine, it is generally due to the 
addition of caramel, the addition being chiefly made on ac- 
count of the erroneous opinion prevailing among the public 
that vinegar clear as water or only slightly colored lacks 

Vinegar prepared from spirits of wine, when carefully evap- 
orated in a porcelain dish, leaves a very small residue of a 
whitish or very slightly yellow color, which chiefly consists of 
the salts contained in the water used for the preparation of the 
alcoholic liquid, an accurate examination showing it to consist 
of calcium acetate, gypsum, and a very small quantity of 
sodium chloride. If the residue is of a dark brown color, 
swells up when heated, and leaves a lustrous black coal, the 
vinegar has been colored with caramel. 

Beer and malt vinegars are dark yellow, generally with a 
reddish shade. On account of their content of dextrin they 
foam when shaken, and, when carefully evaporated, leave a 
brown, gum-like residue. The latter consists chiefly of dex- 
trin, and contains, besides the other extractive substances 
occurring in beer and malt vinegar, such as salts of ashes, 


especially much phosphoric acid. On heating strongly an 
odor calling to mind that of toasted bread is evolved. At a 
still higher temperature the residue turns black and finally acts 
like caramel ; it evolves pungent vapors and leaves a lustrous 

The great content of phosphoric acid characteristic of malt 
or beer-vinegar may also serve for the determination of the 
derivation of such vinegar. By compounding beer or malt- 
vinegar with some nitric acid and a solution of ammonium 
molybdate and heating, the fluid, after standing, separates a 
yellow precipitate, which contains the phosphoric acid present 
in the fluid. 

Wine-vinegar is best recognized by its characteristic odor, 
the latter becoming especially perceptible by rinsing out a 
large tumbler with the vinegar, and after allowing it to stand 
for a few hours examining the odor of the few drops remaining 
in the tumbler. The greater portion of the acetic acid having 
then volatilized, the vinous odor becomes more prominent. 
Cider-vinegar, the odor of which is somewhat similar to that of 
wine-vinegar, can in this manner be plainly distinguished from 
the latter, the residue in the tumbler having an entirely differ- 
ent odor. 

The presence of potassium bitartrate is a characteristic sign 
of wine-vinegar. By evaporating wine-vinegar to a brownish 
syrupy mass, boiling the latter with some water, rapidly filter- 
ing the boiling fluid into a test tube, and adding double its 
volume of strong spirits of wine, a sand-like precipitate falls to 
the/ bottom of the test-tube, which consists of very small 
crystals of tartar. This, however, does not prove the sample 
to be genuine wine-vinegar, tartar also being contained in imi- 
tations. With a sufficiently sharp sense of smell this is, how- 
ever the surest means of distinguishing genuine wine-viriegar 
from a spurious article. 

In case the derivation of a vinegar is to be established with 
absolute certainty, it has to be subjected to an accurate chem- 
ical analysis, and this being better made by an analytical 


chemist, only a few hints are here given which may serve as 
a guide for such analyses. 

In vinegar prepared from a fermented fluid a certain quan- 
tity of glycerin and succinic acid will, as a rule, be present, 
these bodies being always formed by the fermentation of a sac- 
chariferous fluid, and consequently when found the vinegar in 
question cannot have been prepared from an alcoholic liquid 
consisting only of spirits of wine and water. If they are found 
only in very small quantities, the alcoholic liquid used for the 
production of the vinegar consists very likely of spirits of wine 
and water with the addition of beer or fermented whiskey- 
mash, and in this case small quantities of dextrin and of phos- 
phates will also be found. The total absence of tartaric acid 
and the presence of malic acid indicate the derivation of the 
vinegar under examination from fruit, though not necessarily 
from apples or pears, other sacchariferous fruits also containing 
malic acid. A content of tartaric acid is, however, no proof of 
genuine wine-vinegar, as its presence may be due to an inten- 
tional addition, and it is very difficult to arrive at a certain 
conclusion as to the genuineness of a pretended wine-vinegar, 
especially in the case of cider-vinegar to which tartaric acid 
has been added. 

Should pepper, chillies, etc., be added to vinegar for the 
purpose of conferring more pungency, they may be detected 
by neutralizing the acid with carbonate of soda and tasting 
the liquor; if these bodies be present, the solution will still 
retain the sharpness peculiar to such spices. 





Constitution of Wood. Wood essentially consists of woody 
fiber, small quantities of salts and sap and a varying quantity 
of hygroscopic water. Woody fiber or cellulose constitutes 
about 96 per cent, of dry wood, and is composed of C 6 H 10 5 ; 
100 parts containing 44.45 parts carbon, 6.17 hydrogen and 
49.38 oxygen. The vegetable sap consists chiefly of water, 
but contains organic as well as inorganic matters, partly in 
solution and partly in suspension. The inorganic constituents 
the ash left after the incineration of the wood are the same 
in all kinds of wood. The quantity of water in wood is gen- 
erally larger in the soft than in the hard varieties. One hun- 
dred parts of wood recently felled contain, according to 
Schubler and Neuffler, the following quanties of water : 

Beech 18.6 

Birch 30.8 

Oak 34.7 

Oak (quercus pedunculata) . 35.4 
White fir. . 37.1 

Common fir 39.7 

Red Beech 39.7 

Alder ... 41.6 

Elm 44.5 

Ked fir. . 45.2 

The branches always contain more water than the trunk. 

Wood is called air-dry when its weight no longer changes 
at an ordinary temperature ; in this state it contains still 17 to 
20 per cent, of water. The latter can be expelled by con- 
tinued heating at 212 F., but wood thus dried re-absorbs 
about 20 per c'ent. of water from the air. 

When felled, nearly all kinds of wood are specifically lighter 
than water. A few varieties are heavier, but these are the 
harder kinds in which the cellulose is so compactly packed as 
to leave very little space for the retention of air. The table 
here given exhibits approximately the specific gravity of the 
different woods : 



. . .0.47 

Ash . . . 

Fir and pine . . 

. . 0.55 

Oak . . . 

Beech ..' 

. . 0.59 


Birch . 



The content of ash is not the same in all woods ; it varying 
considerably in different parts of the same tree and also with 
its age. According to Violet, in the cherry tree the content of 
ash is greatest in the leaves (about 7 per cent.), next in the 
lower parts of the roots (5 per cent.) ; considerably greater in 
the bark than in the wood, in the former from 1.1 to 3.7 
per cent., and in the latter 0.1 to 0.3 per cent. Saussure 
found in the bark of the oak 6 per cent., in the branches 
0.4 per cent., and in the trunk 0.2 per cent, of ash. The ash 
consists chiefly of carbonates of calcium, potassium, and sodi- 
um, further of magnesia and the phosphates of different bases. 

The average composition of 100 parts of air-dry wood is : 
Carbon 39.6 parts, hydrogen 4.8, oxygen and nitrogen 34.8, 
ash 0.8, hygroscopic water 20 ; and that of artificially dried 
wood : Carbon 49.5, hydrogen 6, oxygen and nitrogen 43.5, 
ash 1. 

Decomposition of wood. Cellulose when carefully treated re- 
mains unchanged for a long time, even thousands of years. 
Wood is, however, subject to greater changes, though under 
especially favorable circumstances it may last for several cen- 
turies. In the presence of sufficient moisture and air the ni- 
trogenous .bodies of the sap are, no doubt, first decomposed, 
and the decomposition being next transferred to the woody 
fiber, the latter loses its coherence, becomes gray, then brown, 
and finally decays. Hence, wood rich in water decays more 
rapidly than dry wood. 

Wood to be preserved should, therefore, be as dry as pos- 
sible, and the nitrogenous bodies, which can be but incom- 
pletely removed by lixiviation, be converted into insoluble 
combinations ; tar and one of its most .effective constituents 
creosote mercuric chloride, blue vitriol, chloride of zinc, and 
many other substances having been recommended for this 


purpose. Moreover, it has been successfully attempted to 
produce certain insoluble bodies, such as aluminium and cop- 
per soaps, in the interior of the wood by saturating it with soda 
soap and then with aluminium chloride, or blue vitriol, or such 
as barium phosphate, by saturating with sodium phosphate 
and then with barium chloride, etc. 

By heating to 212 F. wood remains unchanged, it yielding 
up only sap constituents. If, however, the temperature be in- 
creased, for instance to 392 F., a small quantity of sugar is, 
according to Mulder, formed from cellulose in a closed vessel, 
and from" wood, according to G. Williams, an acid not yet 
thoroughly known, methyl alcohol (see further on), an oil 
boiling between 277 and 421 F., and a small quantity of 

In the presence of water, wood in a closed vessel is, however, 
already decomposed at about 293 F. If this temperature be 
kept up for a long time, for instance, a month, the wood, 
according to Sorby, is converted into a lustrous black mass 
with the formation of acetic acid and gases. 

According to Daubree, pine, when heated for some time with 
water in an entirely closed vessel to 752 F., is converted into 
a mass having the appearance of stone-coal and approaching 
anthracite in its behavior. Baroulier made similar observa- 
tions, masses resembling stone-coal being formed by pressing 
saw-dust, stems and leaves together in moist clay and heating 
continuously to from 392 to 572 F., so that the vapors and 
gases could only escape very slowly. 

By avoiding all heating, concentrated sulphuric acid converts 
cellulose into a gum-like body dextrin which by diluting 
with water and long digesting is converted into sugar (starch 
sugar). When heated, the wood, however, turns black and is 
completely destroyed, sulphurous acid being at the same time 
evolved. With concentrated sulphuric acid, cellulose swells 
up and gradually dissolves, being precipitated by water in 
white flocks. The starch-like body thus obtained is called 
amyloid. It is an altered cellulose and is colored blue by 


iodine. At the ordinary temperature, wood is but little 
affected by dilute sulphuric aci.d, while at a higher tempera- 
ture a certain quantity of sugar glucose or dextrose is 
formed, water being, absorbed at the same time. This be- 
havior has been utilized for obtaining alcohol by fermenting 
the sugar .thus obtained with yeast after neutralizing the acid 
by calcium carbonate, for instance, chalk. The woody fiber 
remaining unattacked can be used as material for paper. 

Concentrated hydrochloric acid colors wood rose color to 
violet-red and rapidly destroys it. Dilute hydrochloric acid 
on heating, forms sugar ; but, according to Zetterlund, the 
quantity of absolute alcohol obtainable in this manner is very 
small, amounting to about 2.3 per cent, of the weight of the 
wood.* By macerating wood with dilute hydrochloric acid at 
an ordinary temperature, the cellulose is not changed, but the 
so-called lignin seems to be dissolved. By forcing dilute hy- 
drochloric acid by a pressure of two atmospheres into trunks 
provided with the bark, and subsequent washing out in the 
same manner with water, and drying by means of a current of 
air at 98.6 F., wood acquires great plasticity. In a moist 
state wood thus treated can be pressed together to one-tenth of 
its original volume. 

Hydriodic acid reduces wood to various hydrocarbons, water 
being formed and iodine liberated. 

Concentrated nitric acid, or, still better, a mixture of it and 
sulphuric acid, converts cellulose, for instance, cotton, into 
gun-cotton, while wood is colored yellow and partially dis- 
solved. Dilute nitric acid, for instance, of 1.20 specific gravity, 
has no effect in the cold, and but little when heated. 

By bringing cellulose in contact with dilute aqueous solu- 
tions of alkalies, it is colored blue by iodine, and consequently 
a starch-like substance is formed, but no humus-like bodies ; 

* According to prior experiments by Bachet, it is, however, claimed that up ta 
23 per cent, of sugar can be obtained from wood % by boiling 10 to 12 hours with 
water containing one-tenth of hydrochloric acid. 


from wood only the lignin is extracted, the woody fibre remain- 
ing unchanged. By heating with strong alkaline lyes, or, still 
better, by fusing with solid caustic alkalies, acetic acid is, ac- 
cording to Braconnot, first formed and then oxalic acid. The 
latter acid is frequently obtained by this process. 

On heating shavings with sodium sulphide an abundant 
quantity of acetic acid (sodium acetate) is formed, the addition 
of sulphur to caustic soda apparently having the effect of pre- 
venting the formation of oxalic acid. 

Products of Destructive Distillation, Besides charcoal, there 
are formed in the decomposition of wood under exclusion of 
air, a great number of products, the kind and quantity of 
which depend on the temperature to which the wood has been 
exposed, as well as on whether that temperature has been slow- 
ly raised to a certain point, or as rapidly as possible. 

The products obtained by gradually increasing the heat are, 
at the ordinary temperature, either gaseous, liquid or solid. 
In speaking of the gases, which will be first considered, a dis- 
tinction has to be made between those which must be accepted 
as actual products of decomposition of wood, and those which 
are formed by certain volatile fluids which are liquid at the 
ordinary temperature, but at higher degrees of heat suffer de- 
composition and yield gaseous products. 

Gaseous products of distillation. At the commencement of 
decomposition, between 320 and 374 F., carbonic acid, CO 2 , 
mixed only with very small quantities of carbonic oxide, CO, 
is chiefly found, the quantity of the latter increasing with the 
rise in the temperature. At between 392 and 428 F. the 
quantities of carbonic acid and carbonic oxide are nearly equal, 
and small quantities of methane or marsh gas, CH 4 , appear. 
At between 608 and 680 F., carbonic acid and carbonic 
oxide become less prominent, and methane appears in larger 
quantities. Above this temperature the content of carbonic 
acid in the gas mixture becomes small, while that of methane, 
mixed also with hydrogen, increases, and heavier hydro- 
carbons make their appearance. 


By igniting the gases escaping from the distilling apparatus, 
a conclusion can be drawn from the appearance of the flame 
as to the kind of products which are developing. At first 
the flame is slightly luminous and shows the characteristic- 
pale blue color of the carbonic acid flame. Later on, in con- 
sequence of the increase in the formation of methane and 
heavier hydrocarbons, the flame exhibits periodically a pure 
white color, while the blue coloration gradually becomes less 
prominent, until finally the gases burn with the luminous 
pure white flame of heavy hydrocarbons. 

The following table shows the order in which the gaseous 
combinations are formed at different temperatures : 

Temperature. Name. Composition. 

{Carbonic acid CO 2 ] 

Carbonic oxide CO 

'55: , 

Ethy'lene C 2 H, lre ' 

From 680 to 812 F. 


(above this temperature ] Butylene C 4 H 8 

only a very small quan- | Benzene C 6 H 6 ~) 

tity of gas is evolved). 

Toluene (-7^8 I Liquid at the or- 

Xylene C 8 H ]0 } dinary temper- 

Cumene C 9 H 12 | ture. 

Napthalene C ]0 H 8 

Pettenkofer found the composition of wood gases as follows : 

Carbonic Carbonic Heavy 

Air. acid. oxide. Methane. Hydrogen, hydrocarbons. 
Up to 680 F. . . 5 54.5 38.8 6.6 

Above 680 F. . . 18-25 40-50 8-12 14-17 6.7 

The process by which the above-mentioned bodies, of which 
the products of benzene caught by cooling may also be vola- 
tilized, are formed is of a very complicated nature, and while 
as regards the formation of many of these bodies only hypoth- 
eses can be advanced, that of others is readily explained. 

Before entering upon this explanation, it is well to remem- 
ber that in the execution of carbonization and destructive dis- 
tillation on a large scale, it is impossible to maintain the same 


temperature in all parts of the apparatus, and that consider- 
able differences in temperature will occur. Furthermore cer- 
tain volatile bodies when highly heated, i. e., in contact with 
hot places of the distilling apparatus, possess the property of 
undergoing decomposition, new combinations being formed. 
This explains the origin of many bodies which appear among 
the products of the decomposition of wood. 

When wood substance is heated, its elementary constituents 
act at first upon each other in such a manner that water is 
formed, and consequently steam is evolved, when the wood, 
after being freed from all moisture, is heated to 320 F. 
However, at a higher temperature the affinity of carbon for 
oxygen and hydrogen asserts itself, and at first combinations 
composed of the three constituents of wood are formed. 

At a certain temperature the affinity of carbon for oxygen 
becomes so potent that the two bodies enter into combina- 
tion, and carbonic acid the combination of carbon richest in 
oxygen is formed so long as an abundance of oxygen is 
present. At a later stage of decomposition, when the quan- 
tity of oxygen in the mass has decreased and the temperature 
has become higher, carbonic oxide the combination of car- 
bon poorer in oxygen appears in larger quantity. It is due 
to the affinity of hydrogen for carbon that two hydrocarbons 
are formed. So long as hydrogen is present in abundance, 
methane CH 4 a combination of carbon with hydrogen com- 
pletely saturated with hydrogen is first formed, and then, at 
a somewhat higher temperature, ethylene C 2 H 4 ,a combination 
poorer in hydrogen. 

The gases above mentioned, namely : Carbonic acid, carbonic 
oxide, methane and ethylene, are very possibly those combi- 
nations which may originate directly from the decomposition 
of the wood substance. When these gases are brought in 
contact with glowing coal, or are highly heated two cases 
which always occur in destructive distillation they suffer 
decomposition, and new bodies appear in the products of 


Carbonic acid in contact with glowing coal changes to car- 
bonic oxide, C0 2 -|-C=2CO, and it is very likely that the con- 
stant increase of the content of carbonic oxide in the gases 
with an increasing temperature, is partly due to this reciprocal 

Hydrogen appears only when the temperature has reached 
a point at which methane and ethylene are formed in abun- 
dance, the hydrogen being split off from these combinations. 
So long as the temperature is not much above 750 F., acety- 
lene, C 2 H 2 , and hydrogen are chiefly formed from methane, 
while at a red heat, methane is directly decomposed to its 
elementary constituents. 

Hence at lower degrees of heat is formed : 

2CH 4 = C 2 H 2 -I- H 6 

methane = acetylene + hydrogen. 

and at higher degrees of heat : CH 4 = C + H 4 . 

On the portions of the iron distilling vessels, which are 
highly heated in the distillation of wood, a graphite-like layer of 
carbon is found which adheres quite firmly and is very likely 
formed by the decomposition of methane and other hydrocar- 
bons in coming in contact with the hot surface, carbon being 
thereby separated. 

Ethylene C 2 H 4 is decomposed at a comparatively low tem- 
perature to acetylene and methane. 

3 C 2 H 4 = 2 C 2 H 2 + 2 CH 4 
ethylene = acetylene + methane. 

At a higher temperature, ethylene is decomposed so that the 
above mentioned products are formed, carbon, however being 
at the same time separated. 

4 C'H 4 = 2 C 2 H 2 -1- 3 CH 4 -f C. 

The above-mentioned decompositions of methane, however, 
are not the only ones which may occur, and according to the 
temperature, there may be formed from these gases a series of 


other combinations. The appearance of propylene may, for 
instance, be explained by the reciprocal action of methane and 
carbonic oxide. 

2 CH 4 + CO = C 3 T7 6 -J- H 2 O 

methane + carbonic oxide = propylene + water. 

Besides the processes of decomposition above represented, 
there are others which are a source of the formation of gaseous 
bodies. At a temperature of between 392 and 536 F. a con- 
siderable quantity of acetic acid and methyl alcohol is already 
formed, and the vapors of this combination are entirely or par- 
tially decomposed when highly heated, and this explains why 
in heating the wood very rapidly, very little acetic acid and 
methyl alcohol are formed, but, on the other hand, a very large 
quantity of gaseous and tar products. 

Wood contains in its sap constituents small quantities of 
nitrogenous combinations and the nitrogen forms with hydro- 
gen, ammonia, which, on coming together with hydrocarbons, 
forms at once substitution products, of which, for instance, 
methylamir.e, in which a portion of the hydrogen in the am- 
monia is replaced by methyl, appears in proportionally largest 

CH 4 + IT 3 N CH 5 N -f H 2 

methyl alcohol + ammonia = methylamine + water. 

Since in the destructive distillation of wood a large quantity 
of gases is evolved, the apparatuses in which the products of 
distillation, liquid at the ordinary temperature, are to be con- 
densed must be quite- large, as otherwise the seams might open 
in consequence of the pressure of the gases ; or at least a large 
quantity of bodies which might be condensed would be carried 
away by the powerful current of gases. 

By destructive distillation 100 kilogrammes of wood yield 
on an average 24.97 cubic meters of gas. This quantity, how- 
ever, corresponds only to the conditions prevailing when dis- 
tillation is carried on slowly. When the heat is rapidly raised 
' 16 


nearly 50 per cent, more of gas is obtained and of course the 
yield of liquid products of distillation and of charcoal is cor- 
respondingly reduced. F. Fischer made thorough investiga- 
tions regarding the gases formed in the destructive distillation 
of wood. He found that the average yield from 100 parts of 
beech is 45 kilogrammes wood vinegar (with 4 kilogrammes 
acetic anhydride and 1.1 kilogramme wood spirit), 23 kilo- 
grammes charcoal, 4 kilogrammes tar, 28 kilogrammes gases 
and steam. 

Liquid Products of Distillation. The products of destructive 
distillation of wood which can be condensed by cooling, sepa- 
rate, when at rest, into two layers, the upper lighter one, which 
is of an acid nature, forming the wood vinegar, while the lower, 
denser one, is termed tar. Since these fluids are formed at 
temperatures widely apart and there is considerable difference 
in the chemical constitution of the bodies contained in them, 
it is best to consider them separately. 

Wood Vinegar. At the lowest temperature at which the de- 
composition of wood commences according to Violette be- 
tween 302 and 312 F., and according to Gillot, even be- 
tween 216.6 and 244.4 F. the three elementary constituents 
of wood act upon each other, and, besides a number of acids 
of the fatty acid series and methyl alcohol, there are formed 
certain products of the decomposition of these bodies. The 
formation of fatty acids, amongst which acetic acid appears in 
largest quantity, commences, according to Gillot, at 255 F., 
and reaches its maximum at 437 F. At higher temperatures 
considerable quantities of products of decomposition of the 
fatty acids appear, so that, according to the temperature and 
duration of distillation, there may be considerable variation, as 
regards the quantities of bodies contained in it, in the composi- 
tion of wood vinegar gained on a large scale. The presence of 
the following fatty acids in wood vinegar has been definitely 
established : 


Formic acid ' . CH 2 O 2 

Acetic acid C 2 H 4 O 2 

Propionic acid C 3 H 6 O 2 

Butyric acid C 4 H 8 O 2 

Valeric acid '. C 5 H ]0 O 2 

Caproicacid C 6 Hi 2 O 2 

Formic acid boils at 212 F., and since the boiling-point of 
the succeeding members of this series of acids lies about 68 
higher, it may be supposed that the lower members of this 
series of acids are found in the portion of the wood-vinegar 
which distils over at a comparatively low temperature. This 
has been fully confirmed by experience, and for this reason the 
wood should be very slowly heated if the largest possible yield 
of acetic acid is to be obtained. 

Methyl alcohol, CH 4 O, may be produced from marsh -gas by 
subjecting that compound to the action of chlorine in sunshine, 
whereby chloromethane, or methyl chloride, CH 3 C1, is pro- 
duced, and then distilling with potash. In the destructive 
distillation of wood it is very likely formed by the action of 
carbonic acid upon methane : 

CH 4 + CO 2 CH 4 + CO 

methane + carbonic acid = methyl alcohol + carbonic oxide, 

so that the appearance of constantly increasing quantities of 
carbonic oxide beside carbonic acid would appear to be ex- 
plained by this process. 

Acetone, C 3 H 6 0, is formed directly from acetic acid by con- 
ducting the vapors of the latter through a red-hot tube whereby 
carbonic acid and water are formed : 

2(C 2 H 4 2 ) = C 3 H 6 + C0 2 + B 2 
acetic acid = acetone + carbonic acid -f water. 

It may, however, be also formed from methyl alcohol and 
acetic acid, or from methyl alcohol and carbonic oxide. The 
occurrence of methyl acetic ether, CH 3 ,C 2 H 3 02, in wood vine- 
gar is due to acetic acid and methyl alcohol in a nascent state 
acting upon each other, while the presence of aldehyde, 


C 4 H 10 2 , may be explained by tbe reciprocal action of methyl 
alcohol and acetic acid, two molecules of methyl alcohol with 
one molecule of acetic acid being transformed to dimethyl 
acetal (= aldehyde) while water and oxygen are liberated, the 
latter being immediately fixed by other products. 

2(CIT 4 0) +C 2 H 4 2 = C 4 H 10 0, + H,0 + O 

methyl alcohol + acetic acid = aldehyde -f water + oxygen. 

Further products of the reciprocal action of the fatty acids, 
methane and carbonic oxide, are: Metacetone, C 6 H 10 0, and 
allyl alcohol or furfurol, C 3 H 6 0. The small quantities of 
nitrogen originating from the sap constituents of the wood, 
which are present in destructive distillation, appear in the 
form of methylamine C 3 H 2 N, and ammonia. 

There is such a variation in the quantities of the bodies of 
which wood vinegar is composed that it is impossible to give 
figures of general value in regard to them, the time during 
which heating takes place being of great influence in this re- 
spect, so that from the same variety of wood, by rapid heating, 
only a few tenths of the quantity of products are frequently 
obtained, which would result by slow heating. This fact is of 
the greatest importance for the practical manufacture of wood 
vinegar and wood spirit, and will be more fully discussed later 
on. It may here only be mentioned that from air dry wood, 
with not too rapid distillation, 30 to 53 per cent, (from most 
varieties of wood on an average 40 to 45 per cent.) of wood 
vinegar may be obtained, the specific gravity of which varies 
between 1.018 and 1.030, and which contains between 2.5 and 
'8.5 per cent, acetic anhydride, calculated from the gravity of 
the wood vinegar. 

Tar. The products which occur in wood tar are still more 
numerous than those which originate during the period in 
which there is still considerable oxygen in the heated mass. 
Among the combinations which may be termed tar products 
in the actual sense of the word, are only a few containing 
oxygen, and these occur only in smaller quantities. The 


larger quantity of the tar products consist of hydrocarbon 
combinations and must be considered as having been formed 
by the elements, carbon and hydrogen, grouping themselves 
in various ways at different temperatures. Ethylene very 
likely breaks up into a series of hydrocarbon combinations, at 
a slightly higher temperature than that at which it originates, 
as is, for instance, shown for naphthalene 

ethylcne = naphthalene + methaner 
8(C 2 H 4 ) = <J 10 H 8 +G(CH 4 ), 

and the formation of all the other hydrocarbons might in the 
same manner be explained. When derived from hard wood, 
wood-tar consists chiefly of parafins,* toluene, xylene, cresol, 
guaiacol, phenol, and methyl derivatives of pyrogallol. 

Since a portion of these combinations is already formed at a 
temperature at which acetic acid is still evolved from the wood, 
certain quantities are found dissolved in wood vinegar, the tar 
products being jointly condensed with the wood-vinegar. 
While, according to Pettenkofer, the heavy hydrocarbons ap- 
pear only at a temperature of above 680 F., according to Gil- 
lot, tar in abundance is already formed at 565 F. Practical 
experience, however, has shown that the largest quantities of 
tar are formed only at a higher temperature, and the boiling- 
points of tar products also indicate a high temperature of for- 
mation, naphthalene, for instance, boiling at 413.6 F. and 
paraffin only at over 572 F. 

Besides the above-mentioned combinations, various chemists 
have established in wood-tar the presence of a long series of 
combinations, but up to the present time they have not been 
more closely examined, or they appear in such small quantities 
that their occurrence is only of theoretical interest. In this 
series may be mentioned : Iridol/ citriol, rubidol, benzidol ; 
further, retene, pittacall, cedriret, and pyroxanthogene ; and 

* Under the name paraffin are very likely comprised many combinations which, 
though having the same percentage composition, possess different physical and 
chemical properties, i. e., are isomeric. 


further, the combinations established by Reich enbach, kapno- 
mar, picamar, creosote and xylite, and finally mesite, prepared 
by Schweizer. 

The yield of tar obtained in the destructive distillation of 
wood depends on the time and temperature used, but also 
essentially on the nature of the wood itself, resinous woods 
yielding larger quantities of tar than the varieties free from 
rosin. By slow distillation, the former yield 9 to 14 per cent., 
and the latter, 5 to 11 per cent, of tar. The more quickly the 
process of distillation is conducted the greater will be the yield 
of tar and gas, while that of acetic acid is less. The table 
below shows the bodies appearing in the destructive distillation 
of wood and the limits of temperature of technical importance, 
within which they are very likely formed : 


Carbonic acid . ) Formic acid ) Qt . AO f^ KWO TT Benzene 1 ^ *i 

Carbonic oxide U20 to 680 F. Acetic acid j" d < 0/z * ' Toluene 

Methane j Propionic acid i Xylene 

Hydrogen 1 Butyric acid ! QQ .,o + 'cno i? < 'umene 

Acetylene | Valeric acid f 92 to 68 F " Naphthalene 

Ethylene }>680 to 809.6 F.Caproic acid J Paraffin 

Propylene | Methyl alcohol 392 to 683 F. Phenol 

Butylene J Acetone 1 Anisol . 

Metacetone .. . 
Acetic acid and 

methyl ether 

Dimethyl acetate 


Methylamine acetate J 

Phenetol .... j r 

482 to 680 F. 

At present only a comparatively small number of the pro- 
ducts originating in the destructive distillation of wood are 
utilized. Of the combinations which belong to the series of 
tar bodies, the only products which have actually found indus- 
trial application, are creosote, which consists chiefly of phenic 
acid, and the light and heavy oils which can be obtained by 
distillation from the tar. 

It is, however, possible to separate from wood tar the various 
combinations contained in it, as has been successfully done 
with coal tar. Benzene, toluene, naphthalene, etc., can be pre- 
pared, and coloring matters manufactured from these hydro- 
carbons. The reason why this is not done is very likely to be 
sought in the fact that in the manufacture of illuminating gas 


from coal, a sufficiently large quantity of coal tar is obtained 
to supply the demand of the manufacturers of coal tar colors. 
Paraffin might also bs obtained from wood tar, but its manu- 
facture would not pay in competition with the article obtained 
from the by-products gained in the purification of crude pe- 

Hence there is nothing left in the destructive distillation but 
to work wood free from rosin into charcoal, acetic acid and 
methyl alcohol as chief products, and to consider all other 
products as by-products, to be utilized as opportunity offers and 
eventually to be used as fuel in the factory. When working 
with wood rich in rosin, it is best first to obtain acetic acid and 
wood spirit at a low temperature, and then to raise the heat to 
such a degree as is required to gain the total quantity of tar, 
since from this tar, by subjecting it to further treatment, tar 
oil can advantageously be prepared. * 

Wood-tar varies in character with the kind of wood from 
which it is obtained, that derived from resinous woods being 
considered the more valuable on account of its content of 
rosin. When wood is distilled in retorts, the portion of tar 
separated from the crude wood-vinegar by settling and that 
skimmed off of the top of the neutralized wood-vinegar are 
united, and, after washing with water, may be sold in the 
crude state as u raw tar" or as " retort tar." It is used for 
preserving wood, for making roofing felts, as an antiseptic, and 
for the preparation of wagon grease and other low-grade lubri- 
cants. In addition to the tar separated by settling, the crude 
wood-vinegar contains considerable tar held in solution by the 
acids and alcohol present, which is recovered when the wood- 
vinegar is distilled, and constitutes what is known as " boiled 
tar." It may be sold as such or burned under the retort, or 
it may be mixed up with the raw tar and subjected to any 
desired treatment. 

By the destructive distillation of resinous woods tar oil con- 
taining turpentine is also obtained, but less wood vinegar, 
eventually calcium acetate. From 50 cubic meters of air-dry 


resinous wood are obtained about 4600 to 4750 kilogrammes 
charcoal, 1500 kilogrammes tar, 400 kilogrammes tar oil, 450 
kilogrammes calcium acetate, 75 to 100 kilogrammes wood- 

Properties of the Combinations formed in the Destructive Distil" 
lation of Wood. Of the many bodies formed in the destructive 
distillation of wood, only a few are of importance, these being 
especially acetic acid, wood spirit and the combinations and 
products of decomposition originating from these two bodies ; 
further the combinations which can be obtained from the tar, 
namely : Creosote and tar oils. 

Acetic acid. The physical and chemical properties of acetic 
acid have already been described on p. 27. Of the products of 
decomposition which acetic acid may yield, those formed by the 
action of heat are here of special interest. Heated by itself, 
acetic acid can stand comparatively very high temperatures 
without suffering decomposition, and acetic acid vapor can, for 
instance, be conducted through a red-hot porcelain tube without 
being decomposed. However, decomposition takes place al- 
ready at a slight red heat when the vapor comes in contact with 
glowing coal, as is the case in the destructive distillation of wood. 
If acetic acid vapor remains for some time in contact with such 
coal, a gas mixture, consisting of methane, carbonic acid' and 
carbonic oxide is formed, the latter originating from the action 
of the coal upon the carbonic acid : 

C 2 H 4 O 2 = CH 4 -f CO 2 . 

acetic acid, methane, carbonic acid. 

Acetone. At a less high temperature, acetone, CH 3 CO.CH 3 , is 
formed by the decomposition of acetic acid ; its formation is 
illustrated by the following equation : 

2(C 2 H 4 2 ) = C a TT 6 4- C0 2 +H 2 O. 
acetic acid acetone carbonic acid water. 

Acetone is always found in wood vinegar, and in a pure state 
is a liquid boiling at 132.8 F., of specific gravity 0.814, of a 


pleasant aromatic odor and a pungent taste. It burns with a 
brilliant flame and is miscible in all proportions with water, 
alcohol and ether. It is an excellent solvent for fats, resins, 
camphor, volatile oils, gun cotton, etc., and in modern times 
quite large quantities of it are employed in the manufacture of 
smokeless gunpowder. 

Methyl acetate is in the chemical sense an acetic methyl ester. 
This ester is formed by the combination of acetic acid with 
methyl alcohol, water being withdrawn : 

CH,.CQQI + CH 3 OH = CH 3 .COO.CH 3 -|- H 2 O. 

By treatment with alkalies such esters are saponified, whereby 
the alcohol and the salt of the acid are again formed. This is 
also the case with the methyl acetate contained in crude wood- 
vinegar when it is distilled with the addition of lime. But, 
as a rule, small quantities of it escape saponification, and for 
this reason the presence of acetic methyl ester can always be 
established in crude wood-vinegar. 

Aldehyde or acetaldehyde has already been described on page 
24. It is a constant constituent of the products of the 
destructive distillation of wood. 

Methyl alcohol or wood spirit, CH 3 OH, in a pure state, is a 
colorless, mobile liquid having a peculiar odor and burning 
taste. When ignited it burns with a slightly luminous flame. 
It boils at 149 F. and has a specific gravity of 0.798 at 32 F. 
It is a solvent for resins and essential oils, and for this reason 
is used in the manufacture of lacquers and varnishes. It may 
also be employed as fuel in place of ordinary alcohol. In 
modern times it has become an important article of commerce, 
it being largely used in the manufacture of aniline colors and 
for many other purposes. 

Crude wood spirit as originally obtained from wood-vinegar 
is a mixture of methyl alcohol, acetic methyl ester, all the 
readily volatile products of decomposition of acetic acid (ace- 
tone, aldehyde, dimethyl acetate) and the readily volatile 


hydrocarbons. The preparation of pure methyl alcohol, which 
will be referred to later on, is therefore connected with certain 

Tar Products Hydrocarbons of the series C n H 2n -6. There 
is considerable variation in the properties of the products oc- 
curring in tar, as far as they are hydrocarbons. Those which 
are liquid at the ordinary temperature are of slight specific 
gravity but have different boiling-points and belong to differ- 
ent series composed according to a certain type. The best 
known are those of the series C n H 2n _ 6) mentioned below. 

Benzene boils at . . - . 179.6 F, Specific gravity . . . .0.850 

Toluene " .... 231.8 F. " " . . . . 0.870 

Xylene " .... 282.2 F. " " . . . . 0.875 

Cumene " .... 330.8 F. " . . . . 0.887 

Cymene " . . . . 345.2 F. ' k ... .0.850 

These bodies possess the property of yielding by substitu- 
tion bases which by treatment with oxidizing bodies can be 
converted into coloring matters, the so-called tar or aniline 
colors. As an example may here be mentioned the conver- 
sion of benzene. Benzene has the formula C 6 H 6 . By con- 

r\ TT "| 

version of benzene into nitro-benzene = 6 5 > and treat- 

N0 2 J 

ment of the latter with hydrogen at the nascent moment, 
aniline is formed : 

E j+6H==C 6 N 6 .NH a 

Nitre-benzine. Aniline. 

According to the same scheme, nitro-combinations and 
amines can be prepared from toluene, cumene, and from all 
other hydrocarbons belonging to this series which can by suit- 
able treatment be converted into coloring matters. 

At present aniline colors are exclusively obtained from coal 
tar, but there is no doubt that they can also be prepared from 
wood tar, though thus far only experiments have been made 


in this direction, which, however, have proved highly suc- 

Besides the hydrocarbons, benzene, toluene, etc., boiling at a 
higher temperature, the presence in wood tar of a few others, 
distinguished by very low boiling points and slight specific 
gravity, has been established. Such are: 

Iridol boils at , . . 116.6 F. Specific gravity 0.660 

Citriol " . . . 125.60 F. tfc " 0.700 

Kubidol" . . .134. 60 F. " " 0.750 

Coridol " ... 140 F. " " 0.800 

Benzidol 1 ' - . .158 F. " " 0.850 

By treatment with nitric acid, these hydrocarbons can also 
be converted into nitro-combinations from which, by reduc- 
tion, amines can be prepared, which may be converted into 
colored combinations. However, thus far these bodies have 
not been thoroughly examined. 

Naphthalene and Paraffin. These two hydrocarbons, which 
also occur in wood tar, are solid at the ordinary temperature 
and are distinguished by high boiling points. Naphthalene 
crystallizes in white rhombic leaflets with a peculiar odor and 
burning taste. It fuses at 174.2 F. and boils at 424.4 F. 
Its composition is C 10 H 8 . By treating with nitric acid, 
naphthalene may be converted into nitronaphthalene, 
C 10 H 7 N0 2 , and from the latter naph thy lamine is prepared, 
which serves for the manufacture of yellow and red coloring 

The hydrocarbons with boiling points of 680 to 752 F., 
which occur in wood tar, are designated paraffins and belong 
very likely to the series C n H 2n . According to the material 
from which they are obtained, the melting points of the par- 
affins vary, and all the combinations belonging to this group 
are distinguished by their great chemical indifference. 

Many varieties of wood tar are of a viscous and gritty 
nature, which indicates a large content of paraffin. In fact, 
paraffin was first prepared from beech-wood tar by Reichen- 


bach. However, as previously mentioned, there is at present 
little prospect of the preparation of paraffin from wood-tar 
proving remunerative, on account of the competition with the 
article obtained from crude petroleum. 

Besides the hydrocarbons mentioned, there occur in wood- 
tar small quantities of the following : Chrysene, C 12 H 8 , retene, 
C 18 H 18 , and pyrine, C 15 H 15 . 

Tar Products Containing Oxygen (Creosote). The combina- 
tions containing oxygen which occur in wood-tar are either 
members of the phenol series or belong to the guaiacol series. 
The liquid known as wood-tar creosote consists of a mixture 
of combinations belonging to both series, the compounds be- 
longing to the phenol series being : 

Phenic acid or carbolic acid 6 ]^ 5 | O C 6 H 7 O. 

Creosote C 6 H 4 <^ C 7 H 8 O. 

Ethyl phenate or phenetol C 6 H 3 CH 3 C 8 H 10 O. 

Among these acids, carbolic acid occurs in smallest quan- 
tity. The combinations belonging -to the guaiacol series, 
which are found in wood tar are : 

Pyrocatechin or oxyphenic acid C 6 H 4 <^ C 6 H 6 O 2 . 

M ethyl-pyrocatechin or guaiacol C 6 H 4 <^rT 8 C 7 H 8 O 2 . 

/CH S 

Creosol 6 H 3 OOH 2 C 8 H 10 O 2 . 

Creosote may also be prepared from coal-tar ; chemically, 
however, this creosote consists almost exclusively of carbolic 
acid, and cannot be used for medicinal purposes. 

Wood-tar creosote is a fluid of a peculiar penetrating smoky 
odor. Applied to a mucous membrane or to the raw cuticle, 
it excites severe burning pain, coagulates the albumen of the 


secretion, and may even produce ulceration. It preserves 
meat probably in consequence of its behavior with albumen, 
and the preserving action of smoking meat is due to a content 
of this body in wood-smoke. 

Since the introduction of the manufacture of illuminating 
gas from wood, wood-tar creosotes very rich in carbolic acid 
are found in commerce, and this may be explained by the 
conditions under which the tar from which the creosote has 
been obtained has been formed. 

When illuminating gases are to be obtained from wood, the 
latter must as quickly as possible be heated to a high temper- 
ature, and under these conditions an abundance of carbolic 
acid is formed which passes into the creosote. If, on the other 
hand, destructive distillation is carried on at a slowly increasing 
temperature, tar is obtained which chiefly contains creosol and 
guaiacol. Since carbolic acid is comparatively quite a poison- 
ous body, creosote intended for medicinal use should only be 
prepared at factories which carry on the destructive distillation 
of wood chiefly for the purpose of obtaining acetic acid. 

Besides the above-described constituents, various chemists 
have mentioned a complete series of compounds as occurring 
in wood-tar. It can scarcely be doubted that several, but lit- 
tle known, bodies which have not yet been prepared in a pure 
state occur in wood-tar, but those which have been called 
eupione, picamar, kapnomar, pittacal, cedriret, pyroxantho- 
gene, mesite, xylite, etc., consist very likely of mixtures of 
various bodies. As far as these compounds are known they 
must be considered as hydrocarbons belonging to various series 
of combinations. A few of them, like cedriret and chrysene, 
give with acids characteristic color reactions, and pittacal is 
itself of a beautiful dark blue color. On heating it evolves 
ammonia, and hence it contains nitrogen very likely in the 
form of combinations known as substituted ammonias. 

None of these combinations have thus far become of any 
technical importance, but they are occasionally observed in 
the purification of sodium acetate. The melt of the crude salt 


when not yet sufficiently roasted yields, when treated with 
water, solutions of a beautiful blue, violet, red to orange color, 
these colorations being produced by the products of decompo- 
sition of the tar substances. 



IN installing a plant for the purpose of utilizing wood in a 
thermo-chemical way, i. e. } a factory in which chiefly pure acetic 
acid and wood spirit, and eventually the tar-products tar oils 
and creosote are to be produced, apparatus will evidently 
have to be selected, the arrangement of which is as complete as 
possible, and which, besides the gaining of all products liquid 
at the ordinary temperature, allows also of the utilization of the 
large quantities of gas evolved in the destructive distillation of 
wood. Hence, according to the object in view in distilling 
wood, the arrangements for obtaining the products of distilla- 
tion may be of very varying nature, the most simple being a 
few suitably-fitted pipes and barrels. Retorts in which the 
temperature can be accurately regulated are the most compli- 
cated and complete, but also the most expensive, apparatus. 

What kind of apparatus has to be used and what kind of 
products are to be prepared, depends entirely upon local condi- 
tions. Since the value of a product increases in proportion to 
the labor expended in the production of it, a manufacturer who 
prepares, besides pure acetic acid and wood spirit, also tar oils 
and creosote, will thus realize the greatest profit from the 
wood, but to attain this object the establishment of a plant 
with all the apparatus required for this purpose is necessary. 

However, many a proprietor of woodland does not care to 
manufacture pure products in a special factory, but desires, 


by the expenditure of a small sum, to obtain from his wood, 
besides charcoal, also wood-vinegar and eventually tar, in order 
to realize, by the sale of these raw products, a larger profit 
from his wood than is attainable by charring alone. In such 
a case the principle of division of labor, and eventually associ- 
ation deserves recommendation, so that the proprietors of the 
woodland would prepare charcoal besides wood-vinegar and 
tar and sell these products, or what is still better, work them 
further in a factory erected at joint expense. 

Some readers may ask the question whether it is possible to 
utilize large quantities of wood by employing them for the 
manufacture of products of destructive distillation. This ques- 
tion may be unconditionally answered in the affirmative, since 
in consequence of the high and steadily increasing tax on alco- 
hol levied in most countries, the price of table vinegar must 
constantly rise. 

There are but two processes by which acetic acid on a large 
scale can be prepared, namely, from alcohol and from wood. 
Up to the present time alcohol can only be obtained from the 
products of agriculture, the chief raw materials being grain 
and potatoes, and eventually grapes and certain varieties of 
fruit, especially apples. 

By taking into consideration the great expense of labor re- 
quired to obtain these products of the soil and to manufacture 
alcohol and acetic acid from them, it will be evident that the 
price of this acetic acid must be greater than of that which can 
in a short time be prepared from wood. Furthermore, vinegar 
prepared from alcohol is never pure, i. e., it does not consist 
only of acetic anhydride and water, but always contains quite 
a quantity of foreign substances in solution, and besides is very 
poor in acetic acid. To obtain the latter pure and in a highly 
concentrated state, vinegar has to undergo almost exactly the 
same chemical manipulations to which wood vinegar has to be 
subjected in order to prepare from it pure concentrated acetic 
acid, but the expense of preparing such acetic acid would be 
very great. 


Pure concentrated acetic acid is at present used on an ex- 
tensive scale in the chemical industries, and is also more and 
more employed in the preparation of table vinegar, since there 
is no difference between pure acetic acid prepared from wood 
and that prepared from alcohol. Wood vinegar, however, can 
be utilized for other purposes besides the preparation of pure 
acetic acid, it being in consequence of its content of tar pro- 
ducts, which have an antiseptic effect, an excellent preserva- 
tive of wood, and the process of impregnating the latter with 
it is decidedly cheaper than most methods in which other 
bodies are employed for the purpose. 

When only acetic acid, wood spirit and tar are to be pro- 
duced, wood waste of all kinds, for instance, saw-dust, ex- 
hausted shavings of dye-woods, spent tan, can be advanta- 
geously worked. If the charcoal obtained from such material 
is to be used as fuel, it must, on account of the smallness of 
the pieces, be moulded to briquettes by a machine constructed 
for the purpose. 

Kilns or Ovens and Retorts. The chief object of the oldest 
method of charring wood, as still carried on in some localities, 
is the production of charcoal without regard to the recovery of 
the available by-products. For this purpose the wood under 
a moveable covering is burnt with the access of air in heaps 
or pits in the immediate neighborhood of where it is cut. The 
attempt to obtain all the products simultaneously, with a 
greater amount of charcoal, probably first led to the substitu- 
tion of stationary apparatus, either of brick-work or iron, in 
place of the covered heaps. Some of these arrangements are 
calculated, like the heaps, to produce the necessary tempera- 
ture for charring, by the combustion of a portion of the wood, 
and the admission of a little air, such as kilns, the sides of 
which form a fixed covering for the substances to be charred. 
In others the portion of the wood destined to produce the heat 
is entirely separated from that to be charred, the latter being 
placed inside, the former outside, the kiln. The yield of ace- 
tate and alcohol is very low even in the best of kilns, and the 


use of the latter has been almost entirely abandoned, they be- 
ing now only employed in localities where charcoal is prac- 
tically the only product recovered. For the sake of complete- 
ness a few of the older constructions will be described. 

Schwartz's Oven. The oven introduced by Schwartz into 
Sweden is based upon the principle that the hot gases furnished 
by a special furnace must pass through the wood piled in a 
closed space and heat it sufficiently for destructive distillation. 
The construction is shown in Figs. 54, 55 and 56. Fig. 54 is 
a ground plan, Fig. 55, a section of the elevation following the 
lines dd, and Fig. 56, another section following the lines cc. 
In the illustrations A A is the space where the wood is carbon- 
ized, b, apertures through which the wood is brought into the 
oven, and the charcoal withdrawn ; c c, the fire-places for heat- 
ing the oven ; d d, openings through which the smoke, car- 
bonic acid, acetic acid, oleaginous and tarry substances pass off 
through the pipes g g, and thence through the condensers into 
the chimney ; e e are knee-pipes which convey the tar condensed 
into the vessels// Fig. 55. The bend in the pipes prevents 
the access of air into the apparatus. H H H H are wooden 
channels wherein the acid and oleaginous matters condense ; i 
is the chimney and k a small opening in the chimney, where a 
fire is lighted to establish a powerful draught. The oven walls 
are of fire-brick or may be of two rows of ordinary brick, the 
interspace being filled with clay and sand. The oven is first 
charged with the heaviest blocks of wood, and between these 
smaller wood is introduced, for the purpose of making the in- 
terior more permeable to the action of the fire. All the orifices 
of the oven are then closed, and the fires at c c lighted, the 
current of air being instituted in i by lighting a fire at k as 
above mentioned. The blaze of the fire traverses the oven 
and carbonizes the charge of wood, and the smoke and other 
vapors from the oven pass by the exit pipes d d into g g, 
whence they escape to the condensers H H, and thence to the 
chimney i. The charge is known to be completely carbonized 
when the smoke issuing at i, which is at first black and heavy, 



becomes bluish and light. The chimney passage is then 
closed, and the opening of the pipes d d stopped up with 

FIG. 54. 

FIG. 55. 

FIG 56. 

wooden plugs and then well luted with plastic clay ; the fire- 
doors are closed and the oven left to cool. At the end of the 
second day, two holes in the top of the oven which hitherto 



had been closed air-tight, are opened, and water is introduced 
to extinguish the red-hot charcoal. The openings are again 
closed for a longer period, and when the oven gets a little 
cooler, more water is added. If any red sparks are observed r 
the openings and pipes must be carefully stopped up, so as to- 
prevent the formation of a current of air, as this would occa- 
sion the combustion of the charcoal and consequently lessen 
the product. 

Great care has to be exercised in accurately regulating the 
access of air, since the smallest quantity of atmospheric oxygen 
which passes through the fire-room without being consumed 
causes a corresponding loss of material in the space where the 

FIG. 57. 

wood is carbonized. Since notwithstanding the utmost care 
and attention, the access of oxygen can never be entirely 
avoided, this oven will seldom be used where the chief object 
is to obtain as large a quantity of acetic acid as possible. An 
essential improvement in the oven might be made by intro- 
ducing generator gases in the heating places and burning 
them by the admission of just a sufficient quantity of air, which 
could readily be accurately regulated, so that a slight reduc- 
ing atmosphere would always prevail in the oven. 

Reichenbach' s oven, Fig. 57, is a square construction with 
double walls, the inner wall of fire-brick and the outer of 
ordinary brick. The space between the two walls is filled 



with sand. The oven is heated by pipes about 2 feet in diam- 
eter which run from one end of the wall to the other, and are 
seen in the illustration at a, 6, c, d and m, n. o, p. The appa- 
ratus having been filled with wood, the upper portion is cov- 
ered with a layer of sods and earth, or with iron plates, the 
joints of the latter being carefully luted with clay. A fire is 
then lighted in the fire-places in front of p and d, which raises 
the temperature of the pipes so high as to cause them to glow. 
The wood in the surrounding spaces of the oven abstracts the 
heat and is thereby carbonized, the volatile products of which 
pass off at the bottom of the oven through the openings at x, 

into the conduit/, #, h, and through y at the opposite side into 
a similar conduit. Both products intermix in the pipe ki, 
where the tar is partly deposited. From the pipe ki, the 
acetic acid vapors are carried off to the condenser. 

Swedish oven. This oven is shown in Fig. 58. The space 
G where the wood is carbonized is vaulted and is provided on 
top with an aperture for charging the wood, which after the 
vault is filled, is closed by a heavy lid luted with clay. The 
pipe A serves for carrying off the products of distillation. The 
bottom of the vault is conical, and in the center is provided with 
thetgrate R, below which is the ash-pit C, which can be closed 
by an accurately-fitting slide S. The door T t which is bricked 


up during the process of carbonization, serves for withdrawing 
the finished charcoal, and also for the introduction of a portion 
of the wood. It is immediately closed after the introduction 
through it of some glowing coals. The effect of the latter is to 
ignite a portion of the wood, and combustion is conducted by 
setting the slide 8 so that the vapors are cooled with a certain 
uniformity. In a short time the wood and the walls of the 
oven become so thoroughly heated that combustion can be 
entirely interrupted by closing the slide S, distillation being 
completed by the heat accumulated in the oven. 

An oven of a somewhat different construction is shown in 
cross-section in Fig. 59, and in ground plan in Fig, 60. The 

FIG. o9. 

FIG. 60. 

space in which the wood is carbonized is in the form of a cyl- 
inder and passes above into a vault closed by a heavy iron lid 
a. The brick work of this space is surrounded by another 
brick work 6, and the fire which is ignited at the opposite side 
d circulates between the two walls in the space c c. On the 
upper portion of the oven, at d, are apertures provided with 
slides, which serve for regulating the fire. The products of 
distillation escape through the pipe e on the bottom of the 
carbonizing space. 

The oven is heated so that the interior wall becomes red-hot. 
Firing is interrupted when no more vapors escape from* the 
pipe e. The slide at d is then closed and the oven left to cool 


'until the charcoal is sufficiently cooled off to allow of it being 
withdrawn without fear of ignition. 

*Carbo-oven. In this oven carbonization is effected in a 
WTo-ught-iron vertical cylinder with a capacity of 300 to 400 
cubic meters of wood. The wood is introduced through open- 
ings in the wrought-iron cover of the cylinder. The products 
of distillation pass out through a pipe branching off from the 
lowest part of the bottom. An outlet on the side of the cyl- 
inder serves for emptying the latter. 

Heating is effected by tire-gases produced in a separate 
furnace, which pass through spiral flues surrounding the 
wrought-iron cylinder. The lower portion of the cylinder is 
protected by brickwork from the direct action of the fire-gases. 

In the center of the cylinder stands a large vertical heating- 
pipe divided into halves by a partition. The non-condensable 
gases, as well as the air required for their combustion, can 
pass in through two pipes entering the lower part. The 
smoke-gases coming from the last flue may also be conducted 
through this heating pipe and, mixed with the combustion 
products of the wood-gases, escape to the chimney. 

Retorts. The various forms of apparatus for the destructive 
distillation of wood previously described are of such a con- 
struction as to exclude uninterrupted operation. When a 
charge has been distilled off, the kiln or oven has to stand till 
the charcoal is sufficiently cooled off to allow of its being with- 
drawn. When this has been done the oven must be again 
charged, heated and so on. This is evidently connected not 
only with considerable loss of time, but also of heat, and it 
has been endeavored to overcome this drawback by the use of 

By heating wood in a retort closed air-tight with the ex- 
ception of an opening for the escape of the products of distil- 
lation, and by fitting to this opening a condenser of suitable 
construction, an apparatus is obtained with which all vapor- 
iform products escaping from the wood can be recovered. 
Such an apparatus, though the most expensive, is the best for 
the production of wood vinegar. 



'a. Horizontal retorts. The arrangement of an apparatus for 
the distillation of wood is very similar to that used for the 
production of illuminating gas from coal, the essential differ- 
ence being that the retorts for the distillation of wood must 
lie in fire-places which allow of the heat being slowly and 
uniformly raised, while in making illuminating gas rapid 
raising of the heat is required. Clay being a worse conductor 
of heat than iron, the use of retorts of this material would 
apparently seem advisable for the destructive distillation of 
wood. However, clay retorts have the drawback of being 
fragile and besides cracks are readily formed through which a 

FIG. 61. 

FIG. 62. 

portion of the vapors would escape. For this reason iron retorts 
are as a rule used. Cast iron retorts do not readily burn 
through and are but little affected by the vapors of the acid, 
but they have the drawback of great weight, and defective 
places are difficult to repair. The best material for horizontal 
as well as vertical retorts is hot-riveted boiler plate about 8 
millimeters thick. Defects in such a retort can be readily 
repaired by riveting a piece of boiler plate upon the defective 

A wrought-iron retort of very suitable construction is shown 
in Figs. 61 and 62. It consists of a cylinder 2.2 meters long 
and 1 meter in diameter. On the back end the retort passes, 



as seen in the illustration, into a pipe of such a length that 
about 30 centimeters of it project from the brick work of the 
oven. In front the retort is secured to a cast-iron ring, in the 
groove of which fits a sheet-iron door. This door is pressed 
against the ring by a screw and the joint is made air-tight by 
luting with clay. For the rapid withdrawal of the charcoal, 
the interior of the retort is furnished with a sheet-iron disk 
supported by two rods riveted to it. To the center of this disk 
a chain is fastened which lies upon the bottom of the retort. 
When the door of the retort is opened the chain is seized with 
a hook and on being drawn forward the sheet-iron disk pushes 
the charcoal out. 

To protect the portion of the retort which comes in direct 
contact with the flame it is advisable to apply to it repeatedly 

FIG. 63. 

a mixture of clay and cow hair. This prevents quite well the 
formation of burnt iron which scales off from the portions 
directly heated. 

Fig. 63 shows the manner of bricking in six retorts, two 
being placed in one fire place. In this construction, as will 
be seen from the illustration, the fire-gases pass directly into 
the chimney which is equivalent to a waste of heat. How- 
ever, this heat can be completely utilized either by placing 
upon the retort-oven a pan in which the solution of crude 
sodium acetate may be evaporated, or the fire-gases may be 
used for heating a room in which the wood for the next oper- 
ation is dried. In working wood very poor in water, a smaller 



quantity of wood vinegar is to be sure obtained than with the 
use of ordinary air-dry wood, but it is correspondingly richer 
in acetic acid. 

FIG. 64. 

In Figs. 64 and 65, a a a are the wrought-iron retorts, b the 
hearth, c c the flues, d the chimney. Over the somewhat 
conical neck of the retort is pushed an elbow pipe e which 

FIG. 65. 

dips into the receiver F. The latter is a cast-iron pipe 1 to 2 
feet in diameter according to the number of retorts, and ex- 
tends the entire length of the oven. For the neck of each re- 
tort it carries a tubulure 5} to 7} inches long. The object 



of the receiver is to receive the products of distillation from all 
the retorts and at the same time to hydraulically close the 
-elbow-pipe of each receiver. Hence the vapors not precipi- 
tated in the receiver can continue their way through g to the 
other condensing apparatus h, but cannot re-enter the retorts. 
This is of no slight importance, for if there were no water- 
joint and the vapors should from any cause suddenly cool off, 
the external air might penetrate into the retort, and the latter 
being filled with inflammable gases and vapors of a high tem- 
perature, an explosion would necessarily follow. For making 
the water-joint it suffices for the elbow-pipes to dip f to 1 inch 

FIG. 66. 

into the fluid into the receiver. But as the fluid constantly 
increases, provision must be made for its discharge through a 
pipe, placed below or on the side, into a collecting vessel 
located in another apartment. 

In many plants the gases escaping from the condenser are 
utilized for heating by conducting them under the retorts 
through a suitable pipe system. However, the pipe-system 
should be so arranged as to allow of the gas being conducted 
under any one of the retorts or being shut off from it in case 
of necessity, because if distillation progresses too rapidly, the 
fire under a retort may have to be entirely removed in order 
to moderate the chemical process in the retort. It is advisable 
to arrange the gas conduit so that the gas can also be used for 
heating other apparatus, for instance, evaporating pans, etc. 


In this country what is known as the oven-retort, Fig. 66, 
is largely used in equipping plants for hard-wood distillation. 
This retort is a rectangular wrought-iron chamber, a common 
size being 6 feet wide, 7 feet high and from 27 to 50 feet long, 
according as it is intended for two or more cars loaded with 
wood. The oven is set in brickwork or is made with double 
iron walls with an air space between. It is provided with a 
large door closing air-tight, and is heated by wood, charcoal, 
coal or gas. 

When distillation is finished the cover of the retort is re- 
moved, and the glowing charcoal is with the assistance of the 

FIG. 67. 

previously-described contrivance emptied into cans, which are 
immediately closed with tightly-fitting covers, the latter being 
luted with clay or sand to prevent ignition of the glowing coal 
by the entrance of air. If such retorts as shown in Fig. 66 
are used, coolers, Fig. 67, similar in shape are employed, in 
which the coal is allowed to remain until thoroughly cool. 

b. Vertical Retorts. The principal drawback of horizontal 
retorts is that, on the one hand, charging them is connected 
with some difficulty in case they are longer than two lengths 
of the wood, and, on the other, that defects in them cannot 
as a rule be immediately detected, and that when repairs have 
to be made they have to be taken from the oven. In addi- 



tion a certain number of sheet-iron cans have to be provided' 
for the reception of the charcoal drawn from the retorts. 

The arrangement of the retorts so that they can be lifted 
from the oven and replaced by others has many advantages. 
The operation can be carried on without interruption by re- 
moving a retort in which distillation is finished and replacing 
it by another, in which distillation at once recommences, be- 
cause the hot brickwork throws out heat continuous!}', and 
heating need to be interrupted only during the time required 
for lifting out the retort and replacing it by another. 

The accompanying illustrations show the arrangement of the- 

FIG. 68. 

retort-ovens and the lifting apparatus as devised by Dr. Josef 
Bersch. Fig. 68 shows a retort 12 feet high with a diameter of 
3 feet and 3 inches. It is constructed of boiler-plate 0.315 
inch thick, the bottom, i. e., the portion which is exposed 
directly to the fire, being of plate 0.394 inch thick. The 
upper portion of the retort is provided with a cast-iron ring 
K which, when the retort is lowered into the oven, rests upon a 
flat cast-iron ring P placed upon the brickwork. On this 
ring are four eyes $ which serve for fastening the lifting tackle, 
and the lid of the retort is secured by four pins pushed through 
the openings in the ring. The lid of the retort consists of a 
sheet-iron disk, provided in the center with a conical head- 


piece D which terminates in the pipe H leading to the con- 

Figs. 69 and 70 show the retorts placed in the oven and the 
mechanical contrivance for raising and lowering the retort R. 
On top of the ovens is a track (7, upon which runs a crane with 
a head-piece having the form of a truncated cone. The track is 
continued from the last oven to a brick wall upon which it rests, 
and beneath this track is another one, which runs to the place 
where the charcoal is to be emptied and the retort is to be re- 
filled with wood. The function of this mechanical contrivance 

Fig. 69. 

is as follows : The retort, after the contents have been distilled, 
is, while hot, lifted from the oven by pushing the crane over it 
and drawing it into the hollow pyramid. The crane is then 
pushed over the opening 0, upon which stands a carriage K 
upon the other track E. The carriage is provided with a 
basket-like arrangement for the reception of the retort. The 
retort having been lowered into the basket, the latter is brought 
into a horizontal position by turning a screw without end. The 
carriage, which is actually a dumping-car, is pushed over the 
pit for the reception of the charcoal, and the retort, the lid of 
which is now taken off, is sufficiently inclined to allow the char- 



coal to fall into the pit. The charcoal is protected from igni- 
tion by being covered with wet charcoal dust. The empty 
retort is then again brought into a horizontal position and 
refilled with wood. 

While the retort just coming from the oven is thus handled, 
and the first dumping-car has been pushed away, another 
dumping-car is immediately brought from a side track &' under 

Fig. 70. 

the crane, the retort lifted in, the crane pushed over the empty 
oven, and the retort lowered. 

Since towards the end of distillation the greatest heat must 
be applied in order to obtain the last remnants of acetic acid 
and tar, the sides of the oven are hottest at this period. If 
now immediately after a retort with charcoal has been taken 
out, another one charged with wood is brought into the oven, 
the heat radiating from the sides of the oven suffices to induce 
distillation, and the fire need only be slightly stirred to unin- 
terruptedly carry on the operation. 

One crane and two dumping-cars are sufficient for attend- 


ing twelve to eighteen ovens arranged one alongside the other. 
For a larger number of retorts it is advisable to have two- 
cranes, and to arrange the coarse of the operation as follows : 
One crane, in the pyramid of which is suspended a retort 
filled with wood, which has been lifted from a dumping-car 
standing, for instance, on the right-hand end of the series of 
ovens, is immediately pushed over the oven as soon as the re- 
tort filled with charcoal has been lifted out, and the retort is 
then lowered. The other crane is pushed to the left-hand 
end of the series of ovens, where the retort is lowered, and 
so on. 

By the employment of these contrivances the time required 
for distillation is reduced to a minimum, the operation can be 
carried on without interruption, and it is not necessary to pro- 
vide sheet-iron cylinders for cooling the charcoal, since the- 
latter is dumped from the retorts directly into pits between the 
rails upon which the dumping cars run, where it is cooled by 
covering with wet charcoal dust. 

Distilling apparatus for wood waste. In working wood and 
bark in the various trades a large quantity of waste results 
which, in most cases, is used as fuel. Such waste can, however, 
be utilized to greater advantage by subjecting it to destructive 
distillation for the purpose of obtaining wood-vinegar, tar and 

Halliday's apparatus for the production of acetic acid, etc., 
from sawdust, spent bark from tan-yards and dye woods ex.. 
hausted of their coloring matter, is shown in Fig. 71. The 
waste to be treated is introduced into a hopper B placed above 
the front end of an ordinary cylinder C, in which a vertical 
screw or worm revolves, conveying the material, and in proper 
quantities, to the cylinder, placed in a horizontal position, 
and heated by means of a furnace H. Another revolving 
screw or worm D keeps the material introduced into the retort 
by C in constant agitation, and at the same time moves it 
forward to the end. During its progress through the retort 
the materials are completely carbonized and all the volatile 



products disengaged. Two pipes branch off from the ulterior 
part of the retort, one .F passing downward and dipping into 
-an air-tight vessel of cast-iron, or a cistern of water G, into 
which the carbonized substance falls. The other ascending 
pipe E carries off the volatile products of the distillation into 
the condenser, consisting of pipes of copper or iron immersed 
in or surrounded by water. 

The arrangement of the cylinder A with the screw is sim- 
ilar to the worms used for moving grain, malt, etc., in a 
-horizontal direction. According as the screw revolves with 

Fig. 71 

greater or less rapidity, the materials can for a shorter or 
longer time be exposed to the action of the heat, and accord- 
ing to well authenticated statements, the quantity of acetic 
acid obtained from the wood substance distilled in this appa- 
ratus is larger than that derived from blocks of wood stacked 
in other retorts. 

This fact, however, cannot be ascribed to the construction of 
the apparatus, which is not particularly favorable, but is ex- 
clusively due to the condition of the wood. From the small 
particles of wood the products of distillation escape with far 


greater rapidity than from the large blocks, which must be 
very hot on the surface before their interior is sufficiently 
heated for distillation to commence. Hence the products of 

FIG. 72. 

distillation must pass through the strongly-heated carbonized 
parts, whereby a considerable portion of the acetic acid is de- 

Another apparatus suitable for the distillation of sawdust, 


spent tan-bark, exhausted dye woods and waste of wood in 
general, is shown in Fig. 72. It consists of an iron cylinder, 
18 feet high and 5} feet in diameter, which contains a number 
of bell-shaped rings placed one above the other. In this man- 
ner a kind of annular cylinder is formed which below termin- 
ates in a conical space. 

The materials thrown in at the top are heated in the cylin- 
der, and the vapors in the cavities of the bell-shaped rings pass 
upwards, while the charcoal falls down and is from time to 
time removed. In removing the charcoal, the lower portion 
of the cylinder is closed by a slide, so that by introducing 
material on top of the cylinder, distillation can be carried on 
without interruption. 

The small charcoal resulting in the destructive distillation 
of wood waste, may be utilized in various ways. A portion 
burned upon a grate of suitable construction, for instance, 
a step-grate, serves as fuel in the factory itself, while the re- 
mainder, especially that from sawdust, forms in the finely 
divided state in which it is turned out, an excellent disinfect- 
ing agent. 

The various apparatus employed in the destructive distilla- 
tion of wood having now been described, it may be stated that 
it is impossible to say which is to be preferred, this depending 
largely on local conditions. The decision must particularly be 
influenced by the fact whether the charcoal is of value or not. 
In the first case it will evidently be of advantage to employ 
smaller apparatus, so arranged that besides thoroughly car- 
bonized charcoal, all the wood-vinegar and tar are obtained, 
and further, that the resulting gases can be employed for 
heating the retorts. 

But where the conditions are such as to make it difficult to 
realize on the charcoal, the principal profit of the plant will be 
in the yield of acetic acid and wood spirit, and for this reason 
it is best to carry on the destructive distillation of wood in 
very large retorts, since with their use the temperature can be 
raised very slowly, whereby wood-vinegar very rich in acetic 
acid is obtained. 


Coolers. The products which escape in the destructive dis- 
tillation of wood consist, in addition to acetic acid, water and 
other very volatile products, of very large quantities of gas. 
Since the current of gas is the carrier of vapors, and consider- 
able quantities of gas are evolved at certain stages of the pro- 
cess, provision must be made for the thorough condensation of 
the vapors to prevent the escape into the air of large quanti- 
ties of valuable products of distillation, or their being burned 
with the gases. 

In plants working with a number of retorts, the discharge 
pipes of the latter enter into a common pipe of large diameter, 
and in this condensing pipe, which in a short time after the 
commencement of the operation becomes very hot, the vapors 
and gases entering it are cooled off to a considerable extent, 
since the condenser in consequence of its large surface yields 
considerable heat to the surrounding air. A portion of the 
heavier volatile tar products is already condensed in the con- 
denser, and is drawn off by means of a faucet in the lowest 
portion of the pipe. It might be suitable to place over the- 
condenser a pipe with numerous small perforations, so that a 
spray of water in such quantity that it immediately evapo- 
rates, falls constantly upon the condenser. 

By the use of this contrivance not only a large portion of 
the vapors are liquefied, but another advantage is attained. 
Since by this cooling the tension of the vapors and gases in 
the condenser is diminished, the vapors formed in the retorts 
pass out with great rapidity. This is of great advantage, 
since by the vapors remaining for a long time in the retort a 
considerable quantity of acetic acid is decomposed. Further- 
more, the volume of non-condensed vapors is considerably de- 
creased, so that a cooler of smaller dimensions can be used, 
than would be possible if all cooling had to be done in it. 

Counter-current Pipe Cooler. The arrangement of such a 
cooler is shown in Fig. 73. The pipe J9, containing the vapors 
to be cooled, is surrounded by another pipe W, filled with 
water. From the reservoir placed at a higher level, cold water 



is conducted through the pipe Z to the lowest part of IF, and 
passing through the latter, runs off at A. Since the vapors in 
the lowest part of D have already been cooled off to a great 
extent, they yield but little heat to the water. As the water 
reaches the higher portions of W,-it constantly acquires a 
higher temperature from the heat withdrawn from the vapors, 
.and rinally runs off at A. With a sufficient length of the cool- 
ing pipes and a powerful current of water, the vapors are so 
completely condensed that but very small quantities of acetic 
^icid and wood spirit are carried away by the current of gas. 
To obtain this acetic acid, the gas before being burned is 

FIG. 73. 

allowed to pass through a cylinder d, see Fig. 76, which is from 
3J to 4 feet high and filled with limestone. The acetic acid 
contained in the gas is fixed by the limestone and the calcium 
acetate thus formed can be obtained by lixiviation. 

The cooling pipes should be of considerable length. With 
six retorts in operation at the same time, the length of the 
pipes should be about 130 feet and their diameter 5} inches, 
since otherwise great pressure is caused in the apparatus by 
back pressure of the gases, which results in a decrease in 
'the yield of acetic acid. Hence it is advisable to arrange the 
upper portion of the cooling apparatus so that the pipe TFhas 



an elliptical cross section and contains two pipes D, one along- 
side the other, which in passing out from this portion combine 
to one pipe. 

To prevent obstruction in the pipes by the collection of vis- 
cous tarry substances, it is recommended to give them consid- 
erable inclination and to connect them so that, in case of neces- 
sity, the interior of each pipe can be cleansed with a brush. 
Fig. 74 shows the most suitable way of connecting two pipes. 
The upper pipe is connected w r ith the lower one by means of 
a curved joint secured by screws. 

To prevent the fluid running off from the cooler from being 

Fig. 74 

Fig 7o 

forced by fits and starts from the lower pipe by the current of 
gas, the contrivance shown in Fig. 75 may be used. The pipe 
D, coming from the cooling apparatus, is cut off at an acute 
angle, and extends nearly to the bottom of a cylindrical vessel 
C, to which is fixed a U-pipe R at such a height that the fluid 
in C can rise to the upper edge of the cut end of D. The pipe 
G, fixed in the lid of the cylinder, carries away the gas from C.' 
Since with an increase in the development of gas, the latter, in 
order to escape, needs only to press down a layer of liquid of 
very moderate height, it can pass off without impediment, 
while the distillate which collects in C runs off through R. 


If neither liquid nor gas escapes through D, the discharge of 
wood-vinegar from R ceases at once, and the uiouth of D is 

Box-cooler. In place of the counter-current cooler, the box- 
cooler shown in Fig. 76 is used in some establishments. In a 
long, narrow trough or box of wrought-iron or wood lies a 
series of straight, wide, copper pipes with a gradually decreas- 
ing diameter. The pipes are slightly inclined, so that the fluid, 
running in at the highest point, flows out at the lowest. Out- 
side the trough the pipes are connected by movable elbow 
joints. One end of each pipe is firmly fixed to the wall of the 
trough, while the other, to prevent free expansion, sits loosely 

FIG. 76. 

in a slightly conical socket. The lower end of the last pipe 
divides into two branches, one of them leading downward and 
dipping into the receiver, while the other, as a rule, conducts 
the gases directly under the fireplace. There should be but a 
small space between the collecting pipe a, which conducts the 
vapors to the condenser, and the first condensing pipe, as 
otherwise obstructions might readily be formed by the deposit 
of tar dried by the hot vapors. A constant stream of water is 
conducted through b, along the bottom of the trough, the 
heated water running off at c. 

The development of gas from the wood being very irregular 
and by no means in the proportion desirable for the heating 
of the retorts, it is preferable to collect it in a gasometer and 


distribute it from there as may be necessary, instead of con- 
ducting it directly into the fire. But little gas is developed in 
the beginning of the operation, and much towards the end, 
while the reverse proportion is desirable. 

In case condensation is not very complete, the pipe leading 
to the hearth or gasometer is more or less attacked by acetic 
acid precipitated in it by the access of air. To prevent this 
evil it is advisable to place on the pipe small receptacles pro- 
vided with cocks for the collection and discharge of any fluid 
deposited. These receptacles may also be filled with quick 
lime, which at least fixes the acetic acid, thus rendering it 
harmless for the pipe. The lime is from time to time extracted 
with water to regain the soluble calcium acetate. 

To further cool off the current of gas and render the vapors 
of acetic acid carried along with it harmless for the pipe, Vin- 
cent uses a cylindrical copper receptacle, d, Fig. 76, provided 
with a false bottom, upon which is placed a layer of crystal- 
lized soda from 2J to 2J feet deep. The vapors of water and 
acetic acid dissolve the soda, and the temperature thereby 
being lowered, a further portion of the volatile bodies, especi- 
ally wood spirit, is precipitated. By distilling the fluid thus 
obtained, the wood spirit is regained, and the residue in the 
still used for the preparation of sodium acetate. 

For a condenser for four retorts of a capacity of 141.26 
cubic feet each, Gillot gives the following approved dimensions, 
provided the period of distillation is 72 hours : The diameter 
of the pipe at its entrance into the water trough is 15} inches, 
and at its exit 5} inches ; its total length is 164 to 180 feet, 
this length being divided between 6 straight pieces and their 
elbow-joints. The vat is 26J feet long with a depth of 5J 

Reservoirs for the Product of Distillation. For storing the 
liquid products of the destructive distillation of wood, wooden 
vats 6 or more feet high with a capacity depending on the 
quantity of the daily distillate are generally used, it being ad- 
visable to have them of such a capacity that at least one ol 



them is filled every day. The U-pipe through which the fluids 
run off from the cooling apparatus terminates over a funnel 
fixed to a pipe which runs alongside the vats, and is provided 

FIG. 77. 

on the corresponding places with stop-cocks by means of which 
the fluid can be discharged into any vat desired. 

Each vat is placed so as to incline slightly forward, and on 
the lowest place is provided with a cock, beneath which is a 
gutter. About 8 to 10 inches above the bottom of each vat is 
a cock with a gutter underneath. Figs. 77 and 78 show the 
arrangement of the vats. The pipe E serves for filling the 

FIG. 78. 

vats with the products of distillation; the cocks Tand the 
gutter T l for discharging the tar into the brick reservoir H 
sunk in the floor ; the cocks E and the gutter Ei for drawing 


off the wood vinegar into the small vessel G, to which is- 
secured the suction pipe /S of a pump for the further convey- 
ance of the wood vinegar. 

It is advisable to coat the vats and iron hoops with hot wood 

Collecting boxes. When working on a large scale quite a 
number of vats are required, which involves considerable ex 
pense, together with the disadvantage of occupying considera- 
ble space. It is therefore advisable to use in place of vats 
collecting boxes sunk in the ground. 

Such boxes are best and cheapest constructed of about 3- 
inch wooden planks, every kind of wood being suitable for the 
purpose, since the products of distillation with which the boxes 
become saturated preserves them even in moist soil. From the 
planks prismatic boxes, each about 13 feet long, 13 feet wide 
and 8 feet deep are constructed. The boxes are sunk in the 
ground, and in the corner of each box is placed a small barrel 
F, Figs. 79 and 80, into which can be dipped the suction pipe 
of a pump. The spaces between the planks and the walls of 
the pit are filled with earth, and the joints between the planks 
with pitch. On top each box is provided with a frame, upon 
which is placed a lid made of planks. 

The requisite number of boxes are placed alongside each 
other so that about 3 feet of ground remain standing between 
the sides of every two boxes. The products of distillation run- 
ning off from the cooling apparatus are conducted through a 
pipe running the length of the boxes into the vessel to be 
filled. To prevent a box from being filled too full, all the 
boxes are connected by the wooden pipe R, placed about 15 
inches below the edge. 

When a box has been several times filled with the products 
of distillation, the layer of tar deposited on the bottom is of 
sufficient depth to be pumped out. The suction pipe of the 
pump is then lowered to the bottom of the small barrel in the 
corner of the box, and the tar, with the exception of a small 
portion, can be separated from the wood vinegar by pumping. 


Figs. 79 and 80 show the arrangement of several such collect- 
ing boxes in ground plan and elevation. 

Since the separation of the tar from the wood vinegar takes 
place the more completely the longer the fluids are allowed to 
repose, it is advisable to first fill all the boxes in turn with 
products of distillation and then to work further the contents 
of the box filled first. 

Utilization of the Gases. The gases evolved in the destructive 
distillation of wood may advantageously be used as fuel. In 
the commencement of the operation a gas mixture, very rich 

FIGS. 79-80. 

in carbonic acid, is obtained, which is of little value as fuel, 
but latter on less carbonic acid is evolved and the gas contains, 
besides carbonic oxide, hydrogen and hydrocarbons, which are 
of considerable value as fuel. 

The most suitable plan would be to catch the gases by 
means of a pump from the pipe , Fig. 75, and collect them 
in a gas holder of ordinary construction, and to conduct them 
from the latter by means of pipes to the fire-place. However, 
a gasholder of sufficient capacity to hold the large quantities 
of gas evolved would be rather an expensive affair for a plant 
engaged in the distillation of wood, and it is therefore gener- 


ally preferred to conduct the gas directly to the fire-places 
where it is to be burnt. 

When working with a large number of retorts, the operation 
may be so conducted that the wood or coal fire under the 
retort just placed in the oven is allowed to go out entirely, and 
to fire only with gases escaping from retorts in which distilla- 
tion is in full progress, and from which a large quantity of gas 
is constantly evolved. In factories devoted to the further 
working of the wood vinegar, it is best to conduct the gases of 
distillation under an apparatus which has to be heated almost 
without interruption, for instance, under the pans in which 
the crude sodium acetate is evaporated to crystalization. 

Care should be taken not to ignite the gas escaping from the 
retorts before all the air has been displaced from the entire 
apparatus retorts, condenser and cooler since otherwise an 
explosion might take place by the flame spreading into the 
pipe conduit, which would not only be dangerous, but suffi- 
ciently heavy to tear apart the lute of clay on the pipes for 
the vapors, the condensers, etc. When the vapors escaping 
from a retort condense on cooling to a yellowish colored fluid, 
all the air has been displaced from the apparatus, and the gas 
may be ignited without fear of danger. 



No matter what the arrangement of the apparatus may be 
in which the destructive distillation of wood is to be carried 
on, the course of distillation as regards the succession of phe- 
nomena remains the same, and a distinction has only to be 
made in reference to the kind of product desired, and the dura- 
tion of time for the operation. The latter depends on the 
quantity of wood used at one time ; the larger the latter is, the 


longer the operation will have to be continued, and under 
otherwise equal conditions, more time will be required for the 
complete distillation of a charge of wood, if wood vinegar, tar 
and black charcoal are to be obtained. 

When working with a larger number of retorts, the opera- 
tion should be so arranged that it is carried on uninterrupt- 
edly, this being advisable on account of the division of labor, 
and also to prevent being forced to adopt special expedients 
by reason of the vast quantity of gas evolved at a certain stage 
of the operation. 

With the use of vertical retorts and a suitable lifting tackle, 
the retorts are placed open in the oven and a gentle fire is 
started. At first only steam evolves from the wood, which is 
allowed to escape into the air, and only when a peculiar aro- 
matic odor indicates the commencement of distillation, are the 
lids placed upon the retorts and connected with the cooling- 
apparatus. To make the lid steam-tight, a roll of clay is laid 
upon the edge of the retort and the lid pressed down upon it, 
the clay forced out thereby being smoothed down with an 
elastic steel blade. 

The time during which distillation has to be continued de- 
pends on the size of the retorts, but, as a rule, the operation 
is so conducted that distillation is finished in 12 hours. Of 
course, with the use of very large apparatus in which a great 
quantity of wood is carbonized at one time, distillation re- 
quires several days, since the heating of such a large quantity 
of wood to the temperature of decomposition takes consider- 
able time. When the temperature about 393 F. has been 
reached at which the wood begins to yield more abundant 
quantities of products of distillation, care must be taken to 
keep the fire under the retorts so that the temperature increases 
gradually and reaches 662 F. only in the last period of dis- 
tillation, so that with a distilling time of 12 hours, the tem- 
perature in the retorts remains for about ten hours below 
662 F. To gain practical experience in regulating the tem- 
perature in heating, which is of special importance with new 


ovens, it is advisable to place a thermometer on one of the re- 
torts as follows : In a small aperture in the lid of the retort 
is screwed an iron pipe closed below and open at the top. The 
length of the pipe should be such that the lower end reaches 
to the center of the retort. In this pipe is lowered by means 
of a wire a thermometer graduated to 680 F. (the boiling 
point of mercury). By from time to time consulting this 
thermometer, a conclusion can be drawn as to the degree of 
heat prevailing in the retort. Experienced men can accurately 
judge of the progress of distillation from the quantity of distil- 
late running off, and of the gases escaping simultaneously. 

When, for instance, 5 cubic meters of wood the contents 
of two retorts are to be distilled at one time, the first distil- 
late, in a jet about the thickness of a lead pencil, is obtained 
with correct firing, in about 1 J to '2 hours after the commence- 
ment of heating. The thickness of the jet of fluid does not 
change for hours, and it retains its original yellow color. 
The gas issues in a moderately strong current from the re- 
spective pipe and burns with a pale blue flame, the latter be- 
coming more luminous only later on at a higher temperature 
when hydrocarbons are mixed with the gas. 

When a temperature of about 662 F. has been reached, the 
quantity of distillate suddenly becomes smaller, and the quan- 
tity of escaping gas also decreases. In order to obtain the 
last remnants of the product of distillation, which consist pre- 
dominantly of tar products, the fire is increased, when a more 
abundant quantity of distillate is obtained. However, the jet 
of fluid running off from the cooler is henceforth of nearly a 
black color, due to numerous drops of dark-colored tar pro- 
ducts. The volume of gas becomes larger and these gases 
burn with a very luminous, pure white flame. In this last 
stage of distillation certain precautions have to be observed in 
reference to raising the temperature. If it is raised too 
rapidly at once, such a large quantity of gas is evolved from 
the retorts as to cause a high pressure in the apparatus, which 
is recognized by the force with which the current of gas issues 


from the pipe entering the fire-place. Since in this stage of 
the process the retorts are hottest and their bottoms not seldom 
red hot, there is danger of the riveted places becoming leaky, 
so that in the succeeding operations a considerable quantity of 
products of distillation is lost by 'its escape in the form of vapor 
through these leaky places and being burned. 

When the volume of gas is observed to becoTne greater, 
about 1J hours before the end of distillation, the fire under 
the retort may be allowed to go out entirely, since the heat 
developed in the retorts in consequence of decomposition in 
conjunction with that radiating from the sides of the ovens, 
suffices to finish the operation. When the temperature in the 
retorts rises to 806 F., the evolution of products of distillation 
ceases almost suddenly and the retorts now contain only black 

Since antimony melts at 809.7 F., this metal may be used 
for determining the commencement of the end of distillation. 
For this purpose the thermometer is removed from the pipe 
previously mentioned, and a small crucible containing a piece 
of antimony is lowered by means of a wire into the pipe. 
When the antimony is melted, distillation may be considered 
finished and the retort be at once lifted from the oven. 

The fluid which runs off during distilation is at first wax- 
yellow, but later on oecornes of a darker color, red brown, and 
finally nearly black, and is quite turbid. When allowed to re- 
pose it separates into two or perhaps more correctly into 
three layers, sharply separated one from the other. The low- 
est layer is tar, a thick fluid of a dark, generally pure black 
color; the middle layer, which comprises the greater quantity, 
is wood vinegar, and is of a red yellow or red brown color. 
The upper layer is again of a dark color, and possesses the 
properties of tar, but, as a rule, this tarry mass is present 
in such small quantities that it even does not cover the entire 
surface, but swims upon it like flakes. 

It is advisable to allow the distillates to repose for a consid- 
erable time, the tar thereby separating more completely from 


the wood vinegar, and the latter is obtained as an entirely clear 
red brown fluid, which can be manufactured into acetic acid 
with greater facility than wood vinegar mixed with larger 
quantities of tar. 

By giving the vats intended for the reception of the distillate 
such a size that one vat is filled by the distillate obtained in 
one day, and arranging twelve such vats as shown in Fig. 78 
the contents of the vat filled first can be allowed to repose for 
11 days before the manufacturer is forced to empty it in order 
to make room for fresh distillate. When the wood vinegar and 
tar are to be worked further in the factory itself, the appara- 
tuses intended for this purpose should be of such dimensions 
that the quantity of wood vinegar produced daily can be 
worked up at one time. The quantity of tar being considera- 
bly smaller than that of wood vinegar, it is collected in the res- 
ervoir H, Fig. 78, and larger quantities of it are worked in one 

When the liquid products of distillation are caught in boxes 
sunk in the ground, described on p. 281, the operation may be 
so arranged that the distillate is allowed to run uniterruptedly 
into the first box until it is filled with tar to such an extent 
that not only wood vinegar, but also tar commences to run off 
through the pipe R, Figs. 79 and 80. The tar is then allowed 
to repose for some time, whereby it still better separates from 
adhering wood vinegar, and the larger quantity of pure tar 
thus obtained is then worked up at one time. 

Experience has shown that it is of advantage to allow the 
tar also to repose as long as possible, it having been observed 
that if kept for some time in special reservoirs, a permanent 
separation of the products according to their specific gravitie& 
takes place. On the bottom of the reservoir tar of a very 
viscous gritty nature collects, which is of such thick consist- 
ency that it can scarcely be raised by a pump. The higher 
layers of the tarry mass are of thinner consistency, the upper- 
most being almost oleaginous, and upon them floats a layer of 


wood vinegar, which can from time to time be taken off and 
worked together with that drawn from the vats. 

Yield of Products. The quantities of wood vinegar and tar 
which are obtained from a given quantity of wood depends on 
several factors, namely, on the kind of wood, its content of 
water, and the manner in which distillation itself has been 
conducted. Since these three factors vary very much, it is 
evident that there must be considerable differences in the 
statements regarding the quantities of products of distillation, 
and especially the quantities of acetic anhydride and wood 
.alcohol which can be obtained from crude wood vinegar, be- 
cause by careless manipulation a large quantity of the acetic 
&cid present in wood vinegar is lost. 

In order to obtain accurate data regarding the quantities of 
wood vinegar and tar which can be obtained from a variety 
of wood when working on a large scale, it is necessary to weigh 
the wood worked during a certain time, to determine its con- 
tent of water, to ascertain in a sample of the wood vinegar re- 
sulting from each distillation the quantity of acetic acid and 
wood alcohol, and finally to accurately ascertain the volume 
of vinegar. From the results of such a series of tests and 
from the quantities of pure acetic acid and wood alcohol fur- 
nished by the factory itself, it would be possible to obtain re- 
liable data regarding the quantities of products of distillation 
which may be obtained from a given variety of wood. 

Stolze has published experiments made with the greatest 
care to show the amount and strength of the products obtained 
from the distillation of several kinds of wood. The quantity 
of each kind of wood submitted to destructive distillation was 
one pound, a quantity suitable, in most cases, to form a prece- 
dent for the manufacture on a large scale. The woods were 
all collected at the same time of the year (towards the end of 
January) and only those of nearly the same growth were 
chosen. From Stoltze's table the following figures for the 
most important -varieties of wood have been calculated : 



















100 pounds of birch 
100 pounds of beech 







100 pounds of hornbeam. 
100 pounds of oak 



7 7 


9 1 

26 1 


100 pounus of fir 


4 2 


11 9 



The results obtained by Assmus in manufacturing on a 
large scale are as follows : 

100 pounds of 








Birch 25 to 40 years old .... 
Birch-bark, first extract 
Birch-bark, second extract. 



4 5 


8 8 



27 5 (f\ 





3 2 

2 4 

10 5 


1 3 

5 7 


44 5 


2 3 

9 5 

22 6 


q c 

According to Roth's experience, the trunk-wood of birch 
from 60 to 80 years old and grown upon a high dry soil with 
a limestone sub-soil surpasses the best red beech in the yield 
of acetic acid. He obtained from 100 pounds of this kind of 
wood dried at 140 to 158 F., with heating for 48 hours, at 
a temperature not exceeding 750 F., 40 pounds of wood vin- 
egar of 25 per cent, acetic anhydride, also 2 or 3 per cent, of 
tar, and 30 per cent, of red charcoal suitable for the manufac- 
ture of powder. 

Klar * gives the following yields obtained with retorts. 
The figures refer to anhydrous wood of 100 per cent., expressed 
in per cents, by weight. 


Technologie der Holzverkohlung, 1910. 






of 80 per 

wood spirit 
of 100 per 


Tar oil. 






a - 




























































Very resinous fir 

European fir 

Sawdust from conifera. . . . 






Olive kernels 







Wood vinegar in the state it is obtained from wood finds but 
a limited application. Without further treatment it can in a 
crude state be used only for impregnating wood or for the 
preparation of ferric acetate (red liquor), because a portion of 
the tar products impart to it a penetrating empyreumatic odor 
rendering its use for other purposes impossible. It is also not 
possible to free the wood vinegar from these tar products sim- 
ply by distillation. By repeated rectification highly concen- 
trated acetic acid remaining almost colorless in the air is to be 
sure finally obtained, but it has always a more or less empy- 
reumatic odor which makes it unavailable for comestible pur- 

'The acetic acid can, however, be separated in a perfectly 
pure state from the wood vinegar, and upon this is based not 
only the preparation on a large scale of the various acetates, 
but also, what is perhaps of still greater importance, the pro- 
duction of absolutely pure acetic acid suitable for comestible 


No matter how the wood-vinegar is to be used, it is of great 
importance to separate it as' much as possible from the tar- 
Freshly prepared wood-vinegar is a turbid red-brown fluid. 
By allowing it to stand quietly in a tall vessel a quite thick 
layer of tar separates on the bottom, over which stands the per- 
fectly clear wood-vinegar; a thin, oleaginous layer of light tar 
products also floats sometimes upon the surface of the vinegar. 
As in the further treatment of the wood-vinegar the presence 
of tar causes many disturbances, care must be taken to sepa- 
rate it as much as possible by mechanical means, this being 
effected by allowing the products of distillation to stand in the 
vats for several days the longer the better. 

It has been proposed to heat the wood vinegar by placing a 
copper coil in the vat, and thus effect a more complete sepa- 
tion of vinegar and tar. But independent of the expense, the 
result of this treatment is less favorable than that obtained by 
allowing the products of distillation to stand for a long time,, 
and besides, by heating too much, a portion of the readily 
volatile wood spirit .is evaporated. 

There are several ways by which concentrated acetic acid 
can be obtained from crude wood-vinegar, the one to be selected* 
depending on what the acetic acid is to be used for. When it 
is to be employed for the production of acetates where a slight 
empyreumatic odor is not detrimental, it is best to prepare 
from the crude wood-vinegar distilled wood-vinegar, and work 
the latter into acetates. Crude lead acetate can, for instance, 
be prepared in this manner. 

If the distilled wood-vinegar should be directly used for the 
preparation of the various acetates, salts would be obtained 
which on exposure to the air would turn brown in consequence 
of the oxidation of the tar-products. However, the behavior 
of some acetates in the heat is made use of to obtain from 
them chemically pure acetic acid. While nearly all salts of 
the organic acids are decomposed at a comparatively low tem- 
perature, some salts of. acetic acid can without suffering decom- 
position be heated to almost 750 F. But at this temperature 


all the tar products adhering to the salt are completely vola- 
tilized or destroyed, so that by recrystallizing the heated mass, 
salts are obtained which are free from empyreumatic substances, 
and chemically pure acetic acid can then be made. 

Distilled wood vinegar. Since crude wood vinegar always 
contains tar in solution it is absolutely necessary to get rid of 
it before neutralizing the vinegar and preparing calcium ace- 
tate. High-grade " grey acetate " can only be produced from 
wood vinegar freed from tar, otherwise " brown acetate" con- 
taining at the utmost 67 per cent, calcium acetate is obtained. 
This separation is effected by distillation, the tar remaining 
in the still. 

For this purpose the crude wood vinegar is subjected to dis- 
tillation in a simple still heated by steam, whereby about 7 
per cent, of tar remains in the still. The distillate, called clear 
vinegar, still contains small quantities of volatile oils. They 
are removed mechanically by allowing the clear vinegar to 
stand, or the latter is separated in vats arranged one after the 
other in the manner of Florence flasks. 

Besides acetic acid the clear vinegar contains wood spirit, i. e. 
a mixture of methyl alcohol, methyl acetate, aldehyde, acetone 
and allyl-alcohol, and can be separated from it by repeated 
fractional distillation, whereby the methyl acetate, however, 
passes over into the woodspirit, thus causing losses of acetic 
acid. It is, therefore, better to first neutralize the distilled 
wood vinegar with milk of lime, whereby the greater portion 
of the methyl acetate is saponified, i. e. split into calcium ace- 
tate and methyl alcohol, and then distil it. The crude wood 
spirit is then subjected to rectification and the solution of cal- 
cium acetate is evaporated and allowed to crystallize. 

This method is obviously inexpedient in so far that distilla- 
tion takes place twice. The heat used for the first distillation 
of the crude wood vinegar is therefore lost. Proceeding from 
this point of view, M. Klar has devised the so-called "three 
still system". The mixture of vapors .appearing in the first 
distillation of the crude wood vinegar is at once conducted 


into milk of lime where calcium acetate which remains in 
solution is formed from the acetic acid. The vapors again 
pass into a still filled with milk of lime where any acetic acid 
which has been carried along is fixed. The vapors pass finally 
into a cooler where the wood spirit is condensed. Since the 
boiling point of wood spirit is lower than that of acetic acid, 
the former does not pass over up to the end of the operation. 
The cooler may therefore be previously disengaged and the 
vapors be allowed to escape or be used for other purposes. A 
special advantage of this method is the complete utilization 
of the latent heat of the vapors coming from the first still. 
Moreover the milk of lime in the second and third stills gets to 
boiling whereby the solution of calcium acetate is at the same 
time concentrated. The milk of lime in the still has of course 
to be renewed before it is completely saturated with acetic 
acid. When working according to this method three advan- 
tages are consequently gained in one operation, the crude 
wood vinegar is freed from tar, the wood spirit is separated and 
the solution of calcium acetate is concentrated. A solution 
of calcium acetate of 20 to 35 per cent, is obtained, and a dis- 
tillate with about 10 per cent, wood spirit. 

A great saving in fuel, steam and space is effected by F. H. 
Meyer's system (German patent, 193,382) of distilling the 
crude wood vinegar in multiple evaporators in vacuum. It 
is based upon the fact that all fluids under a decreased air- 
pressure boil at a lower temperature. Hence if vapors with 
a lower temperature than the boiling point of the fluid to be 
evaporated are at disposal for heating purposes, they may be 
used for distillation by correspondingly decreasing the air- 
pressure over the fluid to be evaporated. 

Freshly-prepared distilled wood vinegar is a colorless, very 
acid fluid with an empyreumatic odor. On exposure to the 
air it acquires a brown coloration in consequence of the oxi- 
dation of the empyreumatic bodies. Although a number of 
expedients have been suggested for freeing the distilled wood 
vinegar from the empyreumatic odor and taste, none of them 


have answered the purpose so far as to make it possible to use 
the vinegar for comestible purposes. The surest proof of the 
inexpediency of these methods is found in the fact that none 
of them has been adopted in practice, though by direct con- 
version of the distilled vinegar, table vinegar could be pro- 
duced at a very low price. 

The distilled wood vinegar may, however, be directly used 
for technical purposes, for instance, in the preparation of lead 
acetate, copper acetate, etc. When it is desired to obtain a 
pure preparation, precaution should be taken to change the 
receiver of the apparatus in which the crude wood vinegar 
is distilled when about 80 to 85 per cent, of the total quantity 
of vinegar which can be obtained has passed over, experience 
having shown that the last portions of the distilled vinegar 
are far richer in empyreumatic substances than those passing 
over first. 

Stolze has proposed several methods for the purification of 
wood vinegar, the most simple and cheapest being to add 5 
pounds of finely pulverized pyrolusite to every 100 quarts of 
vinegar, keeping it at nearly a boiling heat for 6 hours, then 
digesting it in the same manner with 40 pounds of freshly 
glowed charcoal pulverized and sifted while hot, and finally 
distilling off to dryness in a shallow cast-iron still. But on 
account of its tediousness and the necessarily large consump- 
tion of fuel, this process, though frequently modified, has been 
almost entirely abandoned. 

According to Tereil and Chateau, the wood-vinegar is puri- 
fied by compounding it, according to its more or less dark color, 
with 10 or 5 per cent, of concentrated sulphuric acid, whereby 
the greater portion of the tar separates in 24 hours. By dis- 
tilling the decanted acid it is obtained almost colorless, but it 
darkens somewhat on exposure to the air, and by saturation 
with soda a slightly colored salt is obtained which can, how- 
ever, be discolored by a small consumption of animal char- 

Rothe employs a peculiar method for the purification of 


wood-vinegar. The greater portion of tar being separated by 
standing, the wood-vinegar with an addition of charcoal is 
rectified from a copper still. The pale yellow watery wood- 
spirit is caught by itself, and the succeeding clear, but strong- 
ly empyreumatic, distillate is pumped into a vat, placed at a 
considerable height, from which it runs into a purifying ap- 
paratus. The latter consists of a cylindrical pipe of stout tin- 
plate. It is about 26 feet high and 1J feet in diameter, and 
is filled with pieces of coke about 0.122 cubic inch in size, 
which rest upon a heavily tinned iron grate placed about 1J 
feet above the bottom of the pipe. Over this column of coke 
the wood-vinegar is poured in an uninterrupted fine spray, 
while in the space between the bottom and the grate a slow 
current of air heated to 104 F. is constantly blown in through 
a nozzle. The empyreumatic oils mixed with the wood-vine- 
gar are oxidized by the oxygen of the warm air, and, in con- 
sequence, the temperature in the interior of the column of 
coke rises to 122 F., and over. The pipe is protected from 
cooling off by a thick layer of felt. The products of the oxi- 
dation of the empyreumatic oils are partially of a resinous 
nature and adhere to the coke, and partially volatile. The 
acetic acid running off through an S-shaped pipe on the bot- 
tom of the pipe is clear, of a pure acid taste, and suitable for 
the preparation of all the acetates as well as of acetic acid. 
The very slight empyreumatic odor disappears by forcing the 
product through a pipe filled with pieces of animal charcoal 
free from lime. The vinegar thus obtained is claimed to be 
suitable for table use. Though a quantity of acetic acid is 
carried off in the form of vapor by the warm dry current of 
air, this loss can be prevented by passing the air through an- 
other pipe filled with calcined soda or lime. 

Experiments have shown that the method above described 
cannot be recommended for practice, because by the resinous 
oxidation-products deposits are soon formed upon the pieces 
of coke which obstruct the free passage of the current of fluid 
and air, necessitating a frequent renewal of the charge of coke. 


Besides a portion of the oxidation-products remains dissolved 
in the vinegar itself, rendering it for this reason alone unfit 
for table use. 

The only way to prepare perfectly pure acetic acid from the 
wood vinegar is to fix the acetic acid to strong bases, strongly 
heat the resulting salts so that all tar substances are volatilized 
or decomposed, and to separate from the salts thus purified 
acetic acid by distillation with strong acids. According to this 
process crystallized acetic acid the chemically pure prepara- 
tion can finally be prepared. 

Production of pure acetic acid from wood vinegar. The basic 
bodies employed in the practice to fix the acids contained in 
wood vinegar are, according to the object in view, either lime 
or sodium, the former being used for the preparation of acetic 
acid suitable for technical purposes, and the latter for that of 
absolutely pure acetic acid fit for comestible use. In many 
plants not equipped with the apparatus required for the pro- 
duction of pure acetic acid, the crude wood spirit is distilled 
off from the wood vinegar and the residue in the still used for 
the preparation of crude calcium acetate, these two raw pro- 
ducts being sold to chemical factories. This course is of 
special advantage where the charges for transporting the 
chemicals are very high, the weight of the crude wood spirit 
and that of the crude calcium acetate being very likely scarcely 
10 per cent, of the weight of the wood used. Besides working 
up the calcium acetate for acetone has also to be taken into 

Since calcium acetate aiid sodium acetate are the technically 
most important salts of acetic acid their preparation will be 
somewhat fully described. 

Preparation of calcium acetate. For the neutralization of the 
crude wood vinegar freed by distillation from wood spirit, 
burnt and slaked lime is generally used, though as acetic acid 
is a strong acid and can with ease displace carbonic acid from 
salts, lime stone i. e. carbonate of lime may also be employed 
for the purpose. The limestone must, however, be quite pure, 


especially as free as possible from organic substances, and' 
neutralization has to be effected in large vessels, as the calcium 
acetate solution foams very much in consequence of the escaping 
carbonic acid ; this drawback is avoided with the use of burnt 

The neutralized fluid should be allowed to stand several 
days so that the tarry substances contained in the wood vinegar 
can collect on the surface and be removed. It is of importance 
to only just neutralize the wood vinegar with lime and not 
use lime in excess, because then a portion of the acid tar- 
products passes already into the layer of tar collecting on the 
surface and can be separated together with it from the calcium 
acetate solution. When this has been done the solution is 
mixed with 1 J to 1 J per cent, by volume of crude hydrochloric 
acid and allowed to rest. The mass which thereby separates 
on the surface consist chiefly of those substances in which creo- 
sote occurs. It is collected and worked by itself for creosote. 

The clear calcium acetate solution is evaporated in shallow 
iron pans, which may be heated by the fire gases escaping 
from the retort ovens. The tarry substances which separate 
during evaporation in the form of pitch-like masses are care- 
fully removed. Evaporation- is continued till the specific 
gravity of the hot fluid is = 1.116 or 15 Be. When this 
point has been reached, the boiling hot, highly concentrated 
solution of the salt commences, on being further evaporated, 
to separate crusts of salt. These crusts are removed and com- 
pletely dried in smaller pans, whilst being constantly stirred. 
In plants having power 'at their disposal, evaporation and 
drying can be effected in one vessel, a circular pan in which 
a stirrer moves uninterruptedly being used in this case. 
When, as previously mentioned, the fire gases escaping from 
the retort ovens are utilized for heating the evaporating pans, 
there is no danger of the decomposition of the calcium acetate 
by overheating of the salt mass, since by simply pushing a 
slide the fire gases can be immediately given another direc- 
tion. Overheating of the mass in drying is indicated by the 


characteristic odor of acetone. ' While calcium acetate is de- 
com posed at between 426 and 428 F., acetone being evolved 
and carbonate of lime remaining behind, the process com- 
mences already at about 302 F. 

It is most expedient to evaporate the calcium acetate solu- 
tion only to a doughy mass which can be lifted out with a 
shovel, and to effect the complete drying of this mass upon 
iron plates forming the bottom of a flat arch and heated by 
the fire gases escaping from the retort ovens. The tempera- 
ture in the arches should be so regulated as to never exceed 
302 F., but the crude salt should be exposed for several hours 
to this temperature, because by long-continued heating at a 
lower temperature a great many more tarry substances are 
destroyed and volatilized than by stronger heating for a 
shorter tim.e, which besides is accompanied by the danger of 
decomposing a portion of the calcium acetate. 

In heating the evaporating pans by a direct fire there is 
always danger of overheating. Besides, the pans soon become 
covered with a crust of calcium acetate, which renders the 
transmission of the heat very difficult. For this reason round 
or square pans heated by steam are as a rule used in large 
modern plants. These pans have a double bottom into which 
steam is conducted. Copper pans are preferable to iron ones, 
since the acetate burning to the pans can be more readily re- 
moved from copper. The use of such pans is, however, only 
advisable for the evaporation of solutions already concen- 
trated. For dilute solutions it is better to first concentrate 
them in multiple evaporators in vacuum, F. H. Meyer's sys- 
tem, German patent 193,382, previously referred to. In this 
apparatus the solution is brought to 30 to 35 per cent, dry 
substance and then transferred to the open pans mentioned 

To avoid the tedious and disagreeable work of completely 
evaporating and drying the calcium acetate in pans, M. Klar 
has devised a continuously-working apparatus. It consists of 
a. revolving hollow iron cylinder heated inside by steam or 


waste gases. In revolving, the heated cylinder dips into the 
calcium acetate solution and becomes coated with a thin layer 
of it, which dries quickly and is removed by scrapers. With 
this apparatus gray acetate with 80 per cent, can be prepared 
from acetate solution in one uninterrupted operation. Since, 
however, the acetate is obtained in the form of a fine, light 
powder, Klar carries on the drying process only far enough to 
-obtain a product which is no longer sticky. This is dried in 
a closed band heated by warm air, and at the same time 

The crude gray acetate thus obtained forms a gray odorless 
mass. It consists of about 80 per cent, calcium acetate and 
is a commercial article. In addition to calcium acetate it 
contains calcium butyrate and propionate, as well as certain 
empyreumatic bodies, and the acetic acid prepared from it 
also contains butyric acid, propionic acid, etc. Hence this 
acetic acid cannot be directly used for comestible purposes, 
but is suitable for most technical uses. Calcium acetate is 
largely used in print works and in dyeing, and also serves for 
the preparation of acetone. 

Preparation of Sodium Acetate. Sodium acetate in a pure state 
can be obtained according to several methods which, however, 
differ from each other only in a certain stage of the operation, 
the latter beginning always with the neutralization of the wood 
vinegar freed from wood spirit. For this purpose sodium car- 
bonate is preferably used, as crystallized soda, in consequence 
of its content of water of crystallization, entails high charges 
for transport. 

Neutralization is effected by adding gradually the sodium 
carbonate to the wood vinegar, as otherwise the escaping car- 
bonic acid causes strong foaming and the fluid would run over 
even with the use of a very tall vessel. Enough soda should 
be added to the wood vinegar for the fluid to contain a very 
small excess of sodium carbonate, because the sodium acetate 
crystallizes with greater ease from a slightly alkaline fluid 
than from a perfectly neutral one. 


After adding the soda the fluid is allowed to rest for one 
day for the separation of the tarry substances, and after remov- 
ing the latter, the fluid is evaporated in shallow pans, which 
are heated by the fire gases escaping from the retort ovens or 
over an open fire. Evaporation is continued until the hot 
fluid shows a specific gravity of 1.23 = 27 Be. The fluid is 
then emptied into the crystallizing boxes, in which, after the 
separation of the crystals of crude sodium acetate, remains the 
mother-lye. The latter is returned to the evaporating pans. 

The mother-lye is at the ordinary temperature a saturated 
solution of sodium acetate, mixed, however, with the bulk of 
sodium butyrate and sodium propionate contained in the 
wood vinegar used. When these mother-lyes are continually 
returned to the evaporating pans, the quantity of sodium buty- 
rate and sodium propionate finally accumulates to such an 
extent that in cooling the fluid evaporated to specific gravity 
1.23, a granular crystal mass is no longer formed, but a soft 
paste is separated. In this case the fluid in the pans has to be 
entirely removed and treated as will be described later on. 

It is of great importance as regards the purification of the 
crude crystals to cool the evaporated fluid very rapidly in 
order to obtain small crystals which retain but little mother- 
lye. For this purpose oblong sheet-iron crystallizing pans 
with slightly inclined sides are used. When the contents of 
the crystallizing vessels have cooled to the ordinary tempera- 
ture, they form a dark-colored paste of crystals which holds 
the entire quantity of mother-lye. 

To separate the crystals as completely as possible from 
mother-lye one of two methods may be adopted, namely, 
draining and washing, or by means of a centrifugal. Accord- 
ing to the first method the crystallizing pans are placed in a 
slanting position, whereby a great portion of the mother-lye 
runs off and is returned to the evaporating pans. The mass of 
crystals is brought into a vat with a false bottom, below which 
is a discharge pipe. When the vat is filled with the mass of 
crystals, water is poured in. The water dissolves a certain 



Fig. 81 

quantity of sodium acetate, and this solution in sinking down 
displaces the mother-lye, a salt of a quite pale brown color 
remaining behind. 

However, as this method requires considerable time and 
leaves the salt in a wet state, it is preferable to free the salt 
from the mother-lye by means of a centrifugal, it being then 
obtained perfectly dry. In distilling this salt with sulphuric 
acid, an acid is obtained which to be sure is still empyreu- 
matic, but which can be directly used for many manufacturing 

To obtain pure sodium acetate, the crude salt is dissolved in 
water by means of steam so that a nearly boiling solution of 
15 Be. is obtained, which is then filtered in a hot state through 
animal charcoal in a filter which can be heated. The filter, 
Fig. 81, consists of an iron cylinder, C, 10 to 13 feet high, en- 
closed in a somewhat larger iron cylin- 
der C. The inner cylinder is filled with 
granulated animal charcoal, and steam 
circulates in the space between the two 
cylinders. To avoid the necessity of 
charging a filter in too short a time 
with fresh animal charcoal, four to six 
of such filters are arranged in a battery. 
When the first filter becomes ineffec- 
tual, it is emptied, charged with fresh 
animal charcoal and placed as the last 
in the battery. Filtration of the hot 
solution should progress only with such 
rapidity that a colorless fluid runs off 
from the last filter. This fluid when 
rapidly cooled deposits small colorless 
crystals which after having been freed from mother-lye by 
means of a centrifugal and dried, pass in commerce as pure so- 
dium acetate. 

However, even to the salt purified in this manner adhere 
certain, though only very small quantities, of sodium butyrate 


and sodium propionate, and the acetic acid prepared from it 
contains the corresponding quantities of butyric and propionic 
acids. The odor of butyric acid is, however, so penetrating 
that its presence in the acetic acid can be immediately detec- 
ted by the sense of smell. By rubbing such impure acetic 
acid upon the palm of the hand, the disagreeable odor of 
butyric acid becomes conspicuous as soon as the more volatile 
acetic acid has evaporated. 

Hence for the preparation of perfectly pure acetic acid such 
as is demanded for comestible purposes, a different course ha& 
to be adopted which to be sure is somewhat more troublesome 
than the previously described process but surely accomplishes 

Fig. 82. 

the object in view. It is based upon the fact that sodium ace- 
tate may be heated to nearly 752 F. without suffering decom- 
position, while sodium butyrate and sodium propionate are 
decomposed and the tarry substances volatilized at a considera- 
bly lower temperature. 

The salt obtained from the first crystallization purified by 
washing or by means of a centrifugal is used for this purpose. 
It is melted in a cast-iron boiler, Fig. 82, about 5 feet in di- 
ameter and about 8 inches deep, equipped with a stirrer 
furnished with two curved blades. The salt at first melts 
very rapidly in its water of crystallization, yielding the latter 
with heavy foaming, so that finally a crumbly yellow-brown 


mass remains behind which constantly emits tar vapors. The 
fire under the kettle is kept up uniformly for about one hour 
and is only sufficiently increased for the mass to melt when 
no more vapors rise from the latter. The melted mass is lifted 
from the kettle with shallow shovels and poured upon sheet- 
iron plates where it congeals to a gray-white cake full of small 

When the operation above described has been correctly 
carried on, the congealed melt contains sodium acetate, car- 
bonaceous matter and such a small quantity of tarry substances 
that, when brought into water, it yields a solution of a very 
pale yellow color. If the heat has been raised too high, a 
portion of the sodium acetate is also decomposed, acetone being 
evolved and soda remaining behind. It may sometimes 
happen that the whole mass takes fire ; the latter is extin- 
guished by throwing crude crystals upon it. 

The melted mass is dissolved in boiling water. The boiling 
hot solution, which is colored dark by suspended particles of" 
carbonaceous matter, is filtered through a filter filled with 
sand and heated by steam, and then quickly cooled in order 
to obtain small crystals which after treatment in a centrifugal 
should be perfectly colorless. Since it is next to impossible 
to heat every portion of the melting mass exactly so long 
until all the coloring matters have been destroyed, solutions- 
of a yellow color yielding yellow crystals are sometimes ob- 
tained. By redissolving these yellow crystals in boiling water 
and passing the solution through an animal charcoal filter 
entirely colorless crystals are also obtained. 

The sodium acetate thus obtained forms colorless crystals of 
the composition NaC 2 H 3 2 -f 3H 2 O, which effloresce on exposure 
to the air. At the ordinary temperature the salt dissolves in 
about three times its quantity by weight of water. With an 
increasing temperature, its solubility becomes much greater 
and the saturated solution, boiling at 255.2 F., contains for 
100 parts of water 208 parts of the salt. When heated the 
salt melts at 172.4 F., yields its water of crystallization, and; 


congeals. It then melts again only at 606.2 F., and in a 
melted state can be heated to between 716 and 752 F., with- 
out suffering decomposition. When heated above this tem- 
perature it evolves acetone, becomes readily ignited in the air, 
and finally leaves a residue consisting of sodium carbonate 
and coal. 

The mother-lyes which in the course of time accumulate in 
the pan and finally no longer crystallize are evaporated to the 
consistency of syrup and stored in vats. In a few weeks they 
are separated from the crude salt and further worked. In 
most plants this is done by evaporating the lye to dry ness and 
incinerating the residue whereby calcium carbonate mixed 
with coal remains behind, which is again used for the neutra- 
lization of wood vinegar. 

When 100 parts of the strongly inspissated lye are mixed 
with 20 parts by weight of strong alcohol and 70 parts by 
by weight of sulphuric acid are gradually added, a black, oily 
layer separates on the surface of the fluid. This layer con- 
sists of crude acetic, butyric and propionic ethers besides 
small quantities of formic, valeric and capric ethers and from 
these raw products all the mentioned acids can be prepared in 
a pure state. 

The purification of the sodium acetate by filtration through 
animal charcoal is at present only seldom practised, the melt- 
ing process being more simple to manipulate and yielding 
better results. 

Sodium acetate can also be prepared from calcium acetate 
by transposition with a soluble sodium salt, the acid of which 
forms with the calcium an insoluble combination. By mixing, 
for instance, a solution of calcium acetate with one of sodium 
sulphate (Glauber's salt), insoluble calcium sulphate is formed 
and sodium acetate remains in solution. The calcium 
sulphate (gypsum) is, however, not entirely insoluble and it is 
therefore far better to effect transposition with the use of 
sodium carbonate whereby calcium carbonate dissolving with 
greater difficulty is formed. 


Preparation of acetic acid from the acetates. For the prepara- 
tion of acetic acid in a free state the calcium acetate is decom- 
posed by an acid and the acetic acid separated by distillation. 
Hydrochloric acid was formerly generally used for the purpose ? 
it having the advantage of forming with the calcium, calcium 
chloride which is readily soluble in water and in distilling pre- 
sents fewer obstacles than the calcium sulphate (gypsum) 
formed by the decomposition of the acetate with sulphuric acid, 
but the latter is now almost exclusively used, this process being 
preferable because, on the one hand, the apparatus required 
for it has been greatly improved and, on the other, the gray 
acetate with 80 to 82 per cent, acetate furnishes a better and 
purer raw material. The further manipulation of the acetic 
acid is then effected in a distilling column which renders it 
possible to prepare at once from the crude acid, perfectly pure 
acetid acid and also glacial acetic acid. 

Hydrochloric Acid Process. The decomposition of the cal- 
cium acetate may be effected by aqueous, as well as by gaseous 
hydrochloric acid. As previously mentioned, the hydrochloric 
acid process has been generally abandoned, it being now in 
use only where brown acetate with about 67 per cent, acetate 
is to be worked. This product being far more impure is for 
that reason not suitable for decomposition with sulphuric acid, 
because the resinous and tarry substances which are present 
in abundance exert a reducing action upon the sulphuric 

The quantity of calcium acetate to be treated is brought in- 
to a vat and after pouring the requisite quantity of hydro- 
chloric acid over it, the mass is thoroughly stirred and then 
allowed to rest for 24 hours. During this time it liquifies and 
tarry substances separate on the surface. These substances 
have to be carefully removed before bringing the contents of 
the vat into a still. 

The quantity of hydrochloric acid required for the decom- 
position of the calcium acetate could ver}^ readily be accurately 
determined if the combinations contained in the salt, which are 


decomposed by hydrochloric acid, were exactly known. But 
this can only be learned from a complete analysis of a sample 
of the calcium acetate. However, in the practice this trouble- 
some work is generally avoided and the required quantity of 
hydrochloric acid is determined by pulverizing a portion of 
the calcium acetate and, after adding to every 100 grammes of 
salt 90 or 95 grammes of hydrochloric acid, distilling the mass 
in a small glass still. The distillate is tested for the presence 
of hydrochloric acid by the addition of solution of nitrate of 
silver. If after a short time the fluid commences to opalesce 
or a caseous precipitate is formed in it, hydrochloric acid is 

A content of hydrochloric acid renders the acetic acid un- 
suitable for many purposes, and, hence, the use of a small ex- 
cess of calcium acetate is advisable. When the operation is 
carefully conducted and especially too rapid distillation con- 
nected with squirting of the mass avoided, the acetic acid then 
obtained contains only traces of hydrochloric acid, and can be 
freed from them by rectification over some calcium acetate. 
With the use of crude hydrochloric acid of 1.16 specific gravity, 
an acid is obtained from the calcium acetate which contains 
between 47 and 50 per cent of acetic anhydride, and possesses 
a yellowish color and a slightly empyreumatic odor and taste. 

Distillation is effected in a copper still which is protected 
from the direct action of the fire by an iron shell. The worm 
may be made of lead and should below be furnished with a 
U-shaped piece which, when distillation begins, becomes 
immediately filled with acetic acid and prevents the entrance 
of air into the worm. By thoroughly washing the worm with 
water after each distillation it is not attacked by the acetic 
acid, or only so slightly that the quantity of lead which by 
these means reaches the acetic acid is insignificant in a product 
intended for technical purposes. 

If rectification of the acetic acid is effected over potassium 
dichromate instead of over calcium acetate, an acid is to be 
sure obtained which contains no hydrochloric acid and is 


colorless, but has still a very perceptible empyreumatic taste. 
Since potassium dichromate, 1 to 1J Ibs. of which -has to be 
used for every 100 Ibs. of acid, is quite expensive, its use for 
the preparation of acetic acid from calcium acetate cannot be 
recommended, since the resulting acetic acid, on account of 
its empyreumatic taste, cannot be used for comestible purposes. 

The decomposition of the acetate can, as previously men- 
tioned, be also effected with gaseous hydrochloric acid, the 
advantage of this process being that concentrated acetic acid 
is at once obtained. The operation is carried on by bringing 
a sufficient quantity of finely pulverized calcium acetate into 
vertical retorts which can be heated from the outside. Gaseous 
hydrochloric acid, previously heated, is conducted through 
the retorts and the escaping vapors of acetic acid are condensed. 
However, with the use of this process, the crude acetic acid 
obtained is very much contaminated with hydrochloric acid, 
especially towards the end of the operation when the greater 
portion of the calcium acetate has already been decomposed. 

Sulphuric acid process. At present the decomposition of the 
calcium acetate is, as previously mentioned, almost exclusively 
effected with sulphuric acid, insoluble calcium sulphate being 
separated which forms a viscid, pasty mass, and finally 
becomes solid. In order to attain complete decomposition the 
mass has to be thoroughly shaken, a work which requires 
considerable expenditure of power. Gypsum is a bad conduc- 
tor of heat, and although heat is liberated during the progress 
of the reaction itself whereby a portion of the acetic acid 
evaporates, to obtain the last remnants of acetic acid which 
are tenaciously held by the gypsum, is connected with diffi- 
culties. With the use of higher temperatures than attainable 
with direct firing the mass can to be sure be so far heated that 
all the acetic acid finally passes over, but a heavy reduction 
of sulphuric acid then also takes place. For this reason the 
more modern processes work with the use of a vacuum and 
steam for heating, far better yields and a purer acid being 
thereby obtained. 


Below a description of an older plant arranged according 
to Biihler for the sulphuric acid process will first be given, 
IFig. 83 a to d. 

: From the lime kiln the roasted calcium acetate is directly 
'thrown through the funnel o into the storage receptacle p, 
which serves also as a measuring vessel for one charge. De- 
composition is effected in shallow cast-iron pans a, equipped 
with stirrers, and the covers of which are furnished with man- 
liole, exhaust pipe, safety valve and inlet for acid. From the 
reservoir I, concentrated sulphuric acid is allowed to run in 
through a lead pipe conduit. For 100 parts of calcium acetate 
GO parts of sulphuric acid are, as a rule, allowed. Decompo- 
sition at first progresses by itself and about J of the acetic acid 
present distils over. Slight heating then becomes necessary. 
'The stirrers must be kept constantly in operation. The acetic 
acid vapors pass from a into a clay condenser c?, and run 
through c into a storage-reservoir d of clay ; all other mater- 
ials would in a short time be destroyed. 

The crude acid still contains impurities, such as sulphurous 
acid, traces of sulphuretted hydrogen, etc., which by its par- 
tial decomposition the sulphuric acid has yielded together with 
the tar of the crude acid ; besides it contains resinous and tarry 
substances and coloring matter which are removed by rectifi- 
cation over potassium chromate. 

For this purpose acid is allowed to run from the reservoir d 
into the still, and after the addition of water is rectified. The 
-apparatuses used at the present time at once furnish a product 
of 09 per cent, and more. In the illustration, e is the column, 
/a pipe condenser with return pipe, and g a condenser for the 
acid-. For the preparation of vinegar for comestible purposes 
the acid is again rectified in the still h, with the addition of po- 
tassium chromate, a perfectly clear product without detrimen- 
tal odor being obtained from the clay condenser i. The still 
h may be of enameled cast iron and is provided with a heating 
jacket. The movement of the fluid is effected by means of 
-compressed air and the munte-jus m, d, and L 


FIG. 83. 

1. Engine-house ; 2. Fire passage; 3. Boiler-house; 4. Lime Kiln ; 5. Storage- 
for calcium acetate ; 6. Lime kiln. 

The preparation of glacial acetic acid is effected by decom- 
posing the sodium salt by means of sulphuric acid. By the 
introduction of sodium sulphate (Glauber's salt) into the calr- 


cium acetate solution, the latter is converted into sodium ace- 
tate solution, saturation being attained when a clear filtered 
sample no longer yields a precipitate of calcium sulphate on 
the further addition of sodium sulphate. 

The solution is drawn off from the sediment and the latter 
lixiviated until exhausted. Concentration to a specific gravity 
of 1.3 is effected in directly heated boilers. The excess of so- 
dium sulphate crystallizing out is brought into perforated bas- 
kets from which the mother-lye again runs into the boilers. 
It is then allowed to settle and clarify for 8 to 10 hours when 
it is drawn of. The sediment consists of admixtures of the 
raw materials which have become insoluble, and other con- 
stituents. In coolers or crystallizing vessels the greater portion 
of the sodium acetate is deposited in three to five days, and 
the crude salt is frequently directly sold. The mother-lye is 
drawn off, is again concentrated, crystallized, and so on until 
exhausted. The residue is then evaporated and heated to a 
red heat in order to obtain sodium carbonate, or heated to 
melting to remove the tar, the sodium acetate thus obtained 
being separated from the coal by dissolving in water. The 
tarry admixtures, tar oils of various kinds, adhere with great 
tenacity to all the products of distillation, even the crystals 
first obtained being not perfectly pure. They are purified by 
again dissolving them, concentrating the solution and crystal- 
lizing. The crystals are then melted in an iron boiler in the 
water of crystallization and, after evaporating the latter, heated 
until melted the second time. The salt is now anhydrous and 
great care is required to prevent it from burning. It is then de- 
composed by concentrated sulphuric acid in glass retorts in a 
sand bath. For 92 parts salt 98 parts sulphuric acid are used. 
From the distillate the glacial acetic acid separates, on cooling, 
in the form of crystals. 

At the present time the vacuum process is generally employed, 
it yielding at once a highly concentrated acetic acid. The 
apparatus used for this purpose as constructed by the firm of 
J. H. Meyer, at Hanover-Hainholz, Germany, consists of cast 


iron boilers which according to the size of the plant, have 
a capacity of from 240 to 3300 Ibs. of calcium acetate. Each 
boiler is equipped with a stirrer. The charge is introduced 
through a manhole in the cover and the boiler is emptied, as 
a rule, through an aperture in the bottom through which the 
gypsum can be pushed out by the stirrer. 

When the gray acetate is uniformly distributed in the boiler, 
the calculated quantity of sulphuric acid is allowed to run in. 
Decomposition then commences, so much heat being thereby 
liberated that a large portion of the acetic acid distils over 
without the use of a vacuum. When distillation slackens, 
vacuum is applied and distillation carried on to the end, the 
bottom of the boiler being at the same time heated by steam. 
From 220 Ibs. of acetate and 132 Ibs. of sulphuric acid, 165 
Ibs. of crude acetic acid with 80 per cent, acid are under 
normal conditions obtained. The crude acid contains small 
quantities 0.005 to 0.05 per cent. of sulphurous acid. 

For the preparation of acid intended for technical purposes 
only, the crude acetic acid is further purified by subjecting it 
once more to distillation in more simple copper stills generally 
provided with a worm silvered inside. For the preparation 
of high-graded, entirely pure acid and of vinegar essence suit- 
able for comestible purposes, the crude acetic acid is decom- 
posed in a column apparatus. 

In order to finally prepare chemically pure vinegar (99 to 
100 per cent.) from that fraction which contains 96 to 98.5 
per cent, of acetic acid, the distillate is further treated with 
potassium permanganate for the oxidation of contaminating 
admixtures still present, and then distilled from the " fine acid 
apparatus ". This apparatus has a still of copper, but a head 
and worm of silver to prevent contamination by copper acetate. 
Generally the first and last runnings only are removed, the 
middle running being perfectly pure acetic acid. 

Glacial acetic acid, of the highest concentration, acidum 
aceticum glaciale, can also be prepared as follows : Freshly de- 
hydrated sodium acetate is distilled with concentrated sulphuric 


acid, or water is withdrawn from high-graded acetic acid by 
rectifying it over fused calcium chloride. 

In the first case 9J parts by weight of sulphuric acid are 
slowly poured upon 100 parts by weight of sodium acetate free 
from water to prevent the escape, without being condensed, 
of a portion of the acetic acid vapors' evolving with great vigor. 
Heat is applied only after the introduction of the total quan- 
tity of sulphuric acid, and the first four-fifths of the distillate 
are caught by themselves, because the last portion of it has an 
empyreumatic odor, while the first portions contain only sul- 
phurous acid which is removed by rectifying the acid over 
potassium dichromate. 

According to the second process glacial acetic acid may 
even be prepared from 50 per cent, acetic acid by distilling 
the latter with fused (anhydrous) calcium chloride. The gla- 
cial acetic acid thus obtained contains considerable quantities 
of hydrochloric acid. It is freed from it by rectification over 
anhydrous sodium acetate, a still with a silver head and worm 
being used, and the precaution taken not to cool the worm too 
much as otherwise the acetic acid might crystallize in it. 

The calcium chloride containing water which remains be- 
hind is dehydrated by heating in shallow vessels and then 
heated to red hot fusion, this being necessary for the destruc- 
tion of all organic substances present. The preparation of gla- 
cial acetic acid should, if feasible, be undertaken in the cool 
season of the year. The distillate running from the condenser 
is collected in stone-ware pots which are covered and exposed 
to a low temperature, the greater portion of the fluid congeal- 
ing thereby to a crystalline mass. The position of the pots is 
then changed so that the portion which has remained fluid can 
run off ; this is added to the next rectification over calcium 
chloride. By placing the pots in a heated room the anhydrous 
acetic acid is melted and then filled in bottles. Glacial acetic 
acid thus prepared will stand the test usually applied in com- 
merce. It consists in bringing the acetic acid together with 
lemon oil. Anhydrous acetic anhydride dissolves lemon oil 


in every proportion, but in the presence of even a very small 
quantity of water solubility decreases in a high degree. 
Another commercial test consists in compounding the acetic 
acid as well as the glacial acetic acid and the diluted acid,, 
with solution of potassium permanganate till it appears rasp- 
berry red ; pure acid remains permanently red, while if em- 
pyreumatic substances are present, t-he red color disappears- 

However, an acid free from empyreumatic substances, but 
containing sulphurous acid, may also exert a discoloring effect 
upon the potassium permanganate solution. It is, therefore, 
advisable before making the test for empyreumatic substances- 
to test the acid for sulphurous acid. This is done by com- 
pounding the acid with potassium permanganate, allowing it 
to stand until discolored and then adding barium chloride 
solution ; sulphurous acid, if present, has now been changed 
to sulphuric acid, the fluid is rendered turbid by barium chlo- 
ride, and after standing for some time a white precipitate is- 
separated. Such acid should again be rectified. 



The acetates, particularly those of calcium, potassium, so- 
dium, barium, lead, copper, aluminium and iron are exten- 
sively used in the industries and are produced in large quan- 
tities. Calcium acetate and sodium acetate are as previously 
explained initial products for the preparation of acetic acid and 
acetone, for which barium acetate may also be used. 

All the acetates are more or less readily soluble in water. 
By the addition of sulphuric acid the acetic acid is liberated 
without perceptible evolution of gas. The solutions of the 
acetates are precipitated by nitrate of silver ; the precipitate 


of acetate of silver is crystalline and soluble in 100 parts of 

When mixed with equal parts of alcohol and double the 
weight of sulphuric acid, acetic ether is evolved, which is 
recognized by its characteristic fruit-like odor. 

Ferric chloride imparts to the very dilute aqueous solution 
an intense bright-red color. 

From other similar combinations the acetates are distin- 
guished by yielding acetone when subjected to destructive 
distillation, and marsh-gas when distilled with caustic potash. 
When heated with arsenic the very peculiar and disagreeable 
odor of cacodyl is evolved. 

Potassium acetate, KC 2 H 3 O r Dry potassium acetate forms a 
snow-white, somewhat lustrous, not very heavy, laminate or 
foliated crystalline, pulverulent mass. It has a warming, 
slightly pungent salty taste, and its odor is not acid. It turns 
red litmus paper slightly blue, but does not redden phenol- 
phthalein. It rapidly absorbs moisture from the air and deli- 
quesces. At the ordinary temperature it is soluble in about 
J part of water or 1 J parts of alcohol. Boiling water dissolves 
eight times the quantity of its weight of potassium acetate, 
such a solution boiling at 329 F. The dry salt when tritur- 
ated with iodine yields a blue mixture, the latter giving with 
water a brown solution. 

When heated, potassium acetate melts, without suffering 
decomposition, at 557.3 F., and on cooling congeals to a 
radiated crystalline mass. On heating to 780 F. acetic acid 
escapes and, after incineration, potassium carbonate colored 
gray by coal remains behind. 

By adding ferric chloride solution to potassium acetate 
solution, a liquid of a blood-red color is obtained which besides 
potassium chloride contains ferric acetate. By heating the 
solution to boiling a red precipitate of basic ferric acetate is 
separated, the supernatant liquid becoming colorless, provided 
sufficient potassium acetate was present and the ferric chloride 
solution did not contain too much hydrochloric acid. 


Potassium acetate is prepared by bringing into a vat or boiler 
purified wood vinegar and adding potash in small quantities. 
The liquid foams, and the tarry substances that separate on 
the surface are removed by means of a perforated ladle. The 
addition of potash is continued till the solution is neutralized 
when it is allowed to settle. The clarified solution is then 
evaporated todryness in an iron pan, the tarry substances ap- 
pearing during this operation being removed. When the 
product is dry, the fire is increased and the salt melted in the 
water of crystallization. When the mass has acquired a but- 
yraceous appearance, the fire is withdrawn and the salt allowed 
to cool, otherwise it would change to potassium carbonate. 
When cold the melt is again dissolved in water, filtered and 
further worked. 

Another method of producing potassium acetate is by decom- 
posing normal acetate of lead (sugar of lead) with pure 
carbonate or sulphate of potassium. To detect the presence 
of lead it should be tested with sulphuretted hydrogen, which 
in the presence of this metal produces a slightly brown pre- 
cipitate. To obtain a pure product the decanted liquid is 
treated with sulphuretted hydrogen, and, after separating 
from the precipitate and adding a small quantity of acetic acid, 
is evaporated in a stone-ware vessel. 

Chemically pure potassium acetate is prepared by bringing 
400 parts of 30 per cent, acetic acid into an acid-proof enameled 
boiler and gradually introducing 138 parts of pure potassium 
carbonate or 200 parts of potassium bicarbonate until the 
solution is finally neutral or shows but a slight alkaline reac- 
tion. Solution has finally to be assisted by heating. 

The solution is then acetified with acetic acid and evaporated 
to a small volume on a steam-bath or better over an open fire. 
Some acetic acid is next added and the mass is then evaporated 
till it is dust-dr}', being constantly stirred with a porcelain 
spatula during this operation. The resulting dust-dry, crumbly 
powder is brought into dry hot vessels, which are immediately 
closed with corks and the latter are coated with paraffine. 


Too strong heating should be avoided, otherwise decomposition- 
takes place, acetone being formed. 

Pure potassium acetate should dissolve in two parts of water 
and the solution must not redden phenol phthalein, otherwise 
it contains more than traces of potassium carbonate. A 5 per 
cent, aqueous solution should not be rendered turbid or colored 
(presence of metals) by hydrogen sulphide, and not altered by 
barium nitrate after the addition of dilute nitric acid, other- 
wise it is contaminated with sulphate. 

Potassium acid acetate or potassium diacetate, KC 2 H 3 2 C 2 H 4 2 , 
is formed by evaporating a solution of the neutral salt in excess 
of acetic acid ; it crystallizes by slow evaporation in long, flat- 
tened prisms. It is very deliquescent and decomposes at 392 
F., giving off crystallizable acetic acid. 

Sodium acetate, NaC 2 H 3 2 . The manner of preparing this 
salt in the manufacture of wood vinegar has already been de- 
scribed. It can be obtained in a manner similar to that of the 
potassium salt by dissolving carbonate of soda in acetic acid, 
evaporating the solution, and setting the liquid aside to crys- 
tallize. The crystals form large, colorless, oblique rhombic 
prisms. Their composition is NaC 2 H 3 2 -f 3H 2 ; they are 
soluble in 3 parts of cold, in a less quantity of boiling, water, 
and in 5 of alcohol. 

The taste of sodium acetate is cooling and saline. When 
exposed to dry air it loses its three equivalents of water, but 
regains them in a moist atmosphere. After being melted it is 
deliquescent and takes up 7 equivalents of water. It becomes 
a liquid, supersaturated solution which crystallizes, with evolu- 
tion of heat, immediately after a fragment of dry or crystallized 
sodium acetate is thrown into it. 

Sodium acetate is used for the preparation of acetic acid, 
acetic ether, and in medicine. It has also been recommended 
for the preservation of animal and vegetable tissues, it being 
used in the form of a powder in place of common salt. 

Ammonium acetate, neutral acetate of ammonia, NH 4 C 8 H 3 2 . 
-This substance is obtained by neutralizing acetic acid with 


carbonate of ammonia, or better, by saturating glacial acetic 
acid with dry ammonia gas. It is very difficult to obtain in 
the crystalline form on account of its aqueous solution giving 
off ammonia when evaporated, thus becoming converted into 
the acid salt. When subjected to dry distillation ammonia gas 
escapes first; above 330 F. there is formed, besides water, 
chiefly acetamide (C 2 H 5 NO), a white crystalline body which is 
also formed, besides alcohol, on heating acetic ether with liquid 
ammonia in a closed vessel to about 266 F. 

In medicine ammonium acetate has long been used as a 

Calcium acetate, Ca (C 2 H 3 2 ) 2 . The preparation of calcium 
acetate has already been described under wood vinegar. 

The crystals of the pure salt form white acicular prisms 
which effloresce in the air and are soluble in water and in al- 
cohol ; they have a bitter, salty taste. They are decomposed 
by heat into acetone and calcium carbonate. A mixture of 
this salt and of potassium oxalate gives, on heating, propylene 
(C 3 H 6 ), while a mixture of carbonates remains behind. By 
destructive distillation of equal equivalents of acetate and ben- 
zoate of calcium, acetophenone (C 8 H 8 0) is obtained, which by 
treatment with nitric acid is converted into nitro-acetophenone 
(C 8 H 7 N0 3 ). By heating the latter with zinc-dust and soda- 
lime, Emmerling and Engler claim to have obtained artificial 
indigo-blue. But the quantity of the latter thus obtained is 
always very small, and it appears to be very difficult to ascer- 
tain the precise condition under which the transformation 
takes place. 

Barium acetate, (C 2 H 3 2 ) 2 Ba+l J H 2 0, finds at present exten- 
sive application in the industries, especially in the preparation 
of acetone, as it is decomposed at a lower temperature than 
calcium acetate, and leaves a residue barium carbonate 
which can again be used for the preparation of the acetate, 
while the residue from calcium carbonate is of no value. 

Barium acetate is prepared from the mineral witheritefin a 
manner similar to calcium acetate, the only difference being as 


to whether the witherite is used in lumps or in the form of pow- 
der. In the first case the wood vinegar is allowed to act for 
some time upon the witherite by allowing it to run over the 
mineral, or after filling several vessels (a battery) with the 
witherite, dissolving it by conducting gaseous acetic acid 
through the vessels. Provisions must of course be made for 
carrying off the carbonic acid that is evolved. 

The use of witherite in the form of powder instead of in 
lumps, is more advantageous ; but as the powder, in conse- 
quence of its own specific gravity has a tendency to settle on the 
bottom, a powerful mixing and stirring apparatus has to be 
provided. When used in the form of a fine powder the with- 
erite must be sifted upon the surface of the fluid containing 
the acetic acid, as it readily forms lumps, which drop to the 
bottom and are dissolved only with difficulty. As the evolu- 
tion of carbonic acid is by no means tumultuous the vessels 
used can be kept quite full. 

The barium acetate solution obtained by either method may 
be neutral but should never show an acid reaction. It is 
passed through a filter press and then evaporated in the usual 
manner, care being taken not to let it boil up ; for this reason 
it is advisable to effect evaporation in a vacuum. 

Crystallization is effected in the customary manner. The 
resulting crystals are freed from the mother-lye and, if not 
colored too dark (by empyreumatic substances), can be imme- 
diately used. Purification is effected by recrystallization, dis- 
solving the crystals in water, by treatment with animal char- 
coal, china clay or bole, but best by a small addition of sulphuric 
acid, whereby barium sulphate is formed which falls to the 
bottom, carrying with it the empyreumatic substances. After 
settling the clear liquor is drawn off or the mixture is passed 
through a filter-press. The clear solution is evaporated in 
the customary manner and, after crystallization, the mother- 
lye is separated and the crystals, if necessary, are once more 
purified. The mother-lyes are utilized by adding them to the 
solutions first obtained. If they contain too many foreign 


substances, they are evaporated to dry ness, dried, ignited and 
used for solution in acetic acid. 

According to another method barium acetate is prepared 
by allowing equivalent quantities of barium chloride and so- 
dium acetate to act upon each other. For this purpose the ade- 
quate quantity of barium chloride is dissolved in water so that, 
if feasible, an oversaturated solution is obtained, and to this 
solution, whilst boiling vigorously, sodium acetate in fine- 
crystals is gradually added. During this reaction the contents 
of the boiler must constantly be kept boiling vigorously. 
Decomposition progresses quite rapidly. The sodium chloride 
which is separated is removed and the progress of reaction 
watched by taking samples. When decomposition is complete, 
the contents of the boiler are allowed to settle, and the solution 
drawn off from the sediment is crystallized. The crystals are 
then separated from the mother-lye and the last remnants of 
the latter removed either by suction or by means of a centri- 
fugal, the crystals being at the same time washed with water 
and, if required, recry stall i zed from pure water. The mother- 
lye always contains common salt and is again utilized for 
dissolving the barium chloride. 

The crystallized barium acetate obtained at the ordinary tem- 
perature contains 1 molecule of water, while that crystallized 
at 32 F. possesses 3 molecules of water and is amorphous with 
lead acetate. On exposure to the air the crystals effloresce 
and the solutions show an alkaline reaction. The salt is sol- 
uble in 1.5 parts of cold, and 1.1 parts of boiling water, and 
in 67 parts of boiling, and in 100 parts of cold, alcohol. 

Strontium acetate. This salt is prepared in a manner similar 
to that of the preceding. The crystals obtained at 32 F. con- 
tain 5 equivalents of water and those at 59 F. 1 equivalent. 

With strontium nitrate it gives a double salt forming beau- 
tiful crystals which contain 3 equivalents of water. On heat- 
ing they first yield their water of crystallization and then 
detonate, a beautiful purple flame being formed. 

Magnesium acetate is prepared by dissolving magnesia alba 


or usta in acetic acid. It crystallizes with difficulty and is 
readily soluble in water and spirits of wine. Only a very small 
portion of the solution is decomposed by ammonia. By de- 
structive distillation it yields acetic acid, while magnesia 
remains behind. 

Aluminium acetate. Large quantities of aluminium acetate 
-are used under the name of red mordant in dyeing, as well as 
for water-proofing tissues. 

Three combinations of aluminium with acetic acid are 
known, namely, normal f aluminium acetate, and two basic 
acetates which according to their content of acetic acid it is 
customary to distinguish as f and aluminium acetates. 

The normal or f aluminium acetate, A] 2 (CH 3 C0 2 ) 6 is obtained 
by decomposing aluminium sulphate with barium acetate, or 
by dissolving aluminium hydrate in the calculated quantity 
of acetic acid. It is only known in a liquid form. When 
evaporated even at below 100 F. it is decomposed to basic- 
acetates of different compositions. In boiling the solution in- 
soluble basic aluminium acetate is separated, the composition 
of which is not yet accurately known. 

The basic aluminium f acetate, A1 2 (OH 2 )(CH 3 C0 2 ) 4 is obtained 
by dissolving aluminium hydrate in the calculated quantity 
of acetic acid. By evaporating the solution at below 100 F., 
it is reduced to a hornlike mass which gives a clear solution 
with water, especially if the latter has been acidulated* with 
acetic acid. By heating above 100 F. insoluble basic alum- 
inium acetate is separated. 

The bade aluminium J acetate, A1 2 (OH 4 )(CH 3 C0 2 ) 2 separates 
on heating or evaporating the solutions of the abovementioned 

For the preparation of aluminium acetate in larger quantities, 
aluminium hydrate is seldom used as the initial material, 
-aluminium sulphate or ordinary alum being generally decom- 
posed by means of a carbonate, lead acetate or calcium acetate. 
The aluminium hydrate thus obtained is then dissolved in 
-acetic acid. 


Aluminium sulphate is as a rule preferred to alum, it being 
cheaper and can also be obtained free from iron, which is of 
great importance as regards the use of aluminium acetate in 
Turkey red dyeing (for alazaririe colors) as iron imparts a 
brown tinge to the red. 

Aluminium acetate is generally prepared by dissolving 30 
parts by weight of aluminium sulphate in 80 parts of cold 
water, then adding 36 parts by weight of 30 per cent, acetic 
acid (of 1.041 specific gravity), and introducing into this mix- 
ture, whilst stirring constantly, 13 parts by weight of whiting 
triturated with 20 parts by weight of water. 

Decomposition does not proceed as smoothly as would ap- 
pear from the chemical equation ; it must be effected so that 
heating of any kind is excluded. 

By reason of the evolution of carbonic acid the decomposi- 
tion-vessel must be of such a size that it is filled only two- 
thirds full. It should be furnished with a stirrer to keep the 
heavy whiting suspended, and thus cause uniformity of de- 

The whiting should be intimately stirred together with 'the 
water and in order to retain admixed impurities such as sand, 
straw, etc., poured in small quantities through a fine-mesh 
sieve. When all the whiting has been introduced the stirrer is 
kept running for 5 or 6 hours longer, and the mass is then al- 
lowed to stand quietly. Since decomposition is not completely 
finished in 24 hours, it is accelerated after that time by again 
running the stirrer for six hours, when the mixture is brought 
into a filter-press and the heavy solution collected by itself. 
The press-cakes are thoroughly washed and the wash- water is 
used for dissolving fresh portions of aluminium sulphate. 
The cakes remaining in the frame of the filter-press may, if 
pure white, be dried and sold as gypsum ; otherwise they can 
be utilized as fertilizer. 

In place of whiting some manufacturers use sodium bicar- 
bonate ; 667 parts by weight of aluminium sulphate are dis- 
solved in 15000 parts by weight of warm water. Into this 


solution are introduced very slowly and whilst constantly 
stirring, 504 parts by weight of sodium bicarbonate, the bicar- 
bonate product of the manufacture of ammonia-soda being 
suitable for the purpose. Alumina in a gelatinous form is 
precipitated. It is allowed to settle, washed free from salt 
and pressed to a weight of 1750 parts. 200 parts by weight of 
the gelatinous aluminium hydrate are dissolved in 150 parts 
by weight of 50 per cent, acetic acid. One liter of the mordant 
thus obtained contains 35.3 grammes of alumina. In place 
of, sodium bicarbonate, ammonia-soda may be used in the 
proportion of 1 part by weight of aluminium sulphate to 3.6 
parts by weight of soda. 

Many manufacturers prefer to effect the decomposition of 
the aluminium sulphate with lead acetate instead of with 
whiting or sodium carbonate. Since lead sulphate is insoluble 
the decomposition of the aluminium sulphate solution is more 
perfect. In practice it is found advantageous to employ equal 
parts of aluminium sulphate and acetate of lead, or even a 
rather less quantity of the latter. The aluminium sulphate 
is dissolved in boiling water, and the powdered lead acetate 
added to the solution. About one-tenth of crystallized carbon- 
ate of soda, or a little carbonate of lime, is added to the alum 
to combine with the free acid. The three following receipts 
serve to indicate the proportions employed : 

I. Dissolve 100 pounds of aluminium sulphate in 50 gallons 
of boiling water, and add 10 pounds of acetate of lead in fine 
powder, stirring the mixture well at first, and likewise several 
times during cooling. 

II. Dissolve 100 pounds of aluminium sulphate in 50 gallons 
of boiling water, add slowly 10 pounds of crystallized carbonate 
of soda, and then stir in 50 pounds of acetate of lead in 

III. Dissolve 100 pounds of aluminium sulphate in 50 
gallons of boiling water, and add in small portions 6 pounds 
of crystallized carbonate of soda, and then stir in 50 pounds 
of acetate of lead, in powder, as before. 


The cheapest method of preparing aluminium acetate is 
from calcium acetate and aluminium sulphate, the principal 
condition being not to use a too tarry gray acetate as other- 
wise the final product turns out too dark and can be decolor- 
ized only with difficulty. Calcium acetate contains, as a rule, 
a larger quantity of calcium carbonate, and this quantity has 
previously to be accurately determined in order to calculate 
the quantity of aluminium sulphate required. In practice 
this calculation is avoided by having always on hand clear 
solutions of both salts and, when an excess of one or the other 
salt is found in the aluminium acetate solution, correcting it 
by the addition of one or the other solution, so that a pure 
aluminium acetate solution results. 

As a rule 100 parts by weight of calcium acetate and 70 
parts by weight of aluminium sulphate are dissolved, each by 
itself, in sufficient water to obtain solutions of 5 to 6 Be. 
The solutions are filtered and after bringing the separate solu- 
tions into the vessels located over the precipitation vat, pre- 
cipitation is effected. On account of the evolution of carbonic 
acid, the vat should not be kept too full. 

When a determined quantity of fluid has been consumed 
and evolution of gas has ceased, a small quantity of the fluid 
in the vat is filtered in a small glass cylinder, the filtrate di- 
vided into two halves, one of which is tested with barium chlor- 
ide solution for sulphuric acid, and the other with ammonium 
oxalate or sulphuric acid for lime. If in one or the other case 
a white precipitate is formed enough of one or the other clear 
solution previously mentioned is added until after taking other 
samples no precipitate or turbidity is formed in them ; the 
aluminium acetate solution then contains only slight traces of 
calcium acetate or aluminium sulphate. 

The contents of the precipitation-vat are passed through a 
filter-press and the residue is washed. The cakes of gypsum 
are not suitable for fertilizing purposes ; by adding air-slaked 
lime and ashes the) 7 may be utilized for repairing roads, etc. 

Manganese acetate, Mn(C 2 H 3 2 ) 2 . This substance is pre- 


pared by dissolving freshly precipitated mangauous carbonate 
(MnC0 3 ) in heated acetic acid, evaporating the solution and 
crystallizing. The crystals are rhombic prisms, and occasion- 
ally in plates of an amethystine color ; they are permanent in 
the air, soluble in alcohol, and in about three times their 
weight of water. 

On a large scale this salt is manufncturedby precipitating a 
-solution of manganous sulphate * by one of lime acetate and 
.agitating the liquor to decompose the whole of the manganese 

It sometimes happens that a portion of the manganese salt 
is not acted upon by the acetate of lime, and in this case a 
concentrated solution of acetate of lead is employed towards 
the end of the process to effect complete decomposition. The 
mixed precipitate of sulphate of lime and lead is filtered off, 
and the filtrate evaporated and crystallized. The best acetate 
of manganese is made by adding to 4 parts of manganous sul- 
phate dissolved in 3 parts of water, 7 parts of crystallized 
acetate of lead dissolved in 3 parts of water, agitating the solu- 
tion, and drawing off the clear liquor for use. 

Acetate of manganese is used in dyeing and calico-printing 
to give a brown color to fabrics. Its principle of action de- 
pends upon the further oxidation of the manganese. 

Iron acetate. Acetic acid combines with ferrous oxide 
(FeO) as well as with ferric oxide (Fe 2 3 ), but only the 
ferrous acetate crystallizes in small greenish-white needles, very 
prone to Oxidation, while ferric acetate is a dark, brownish 
red, uncrystallizable liquid, of powerful and astringent taste. 
Both salts dissolve freely in water, and are of importance for 
dyeing and calico-printing. 

Ferrous acetate, Fe(C 2 H 3 2 ) 2 . Black mordant. For dyeing 

* Manganons sulphate is prepared by mixing the dioxide (pyrolusite) with half 
its weight of concentrated sulphuric acid and heating in a Hessian crucible until 
no more vapors escape. The residue is dissolved in water, filtered, and allowed 
to crystallize at an ordinary temperature. The solution of the salt when decom- 
posed with crystallized soda gives a precipitate of manganous carbonate. 


purposes this salt is prepared by dissolving wronght-iron 
turnings in wood-vinegar, care being had that some iron 
remains undissolved, as otherwise the salt, on exposure to the 
air, is gradually partly converted into the ferric salt. This 
oxidation proceeds, however, but slowly, the empyreumatic 
substances contained in the wood vinegar rendering the con- 
version rather difficult. The pure salt oxidizes with great 
rapidity. For commercial purposes this compound is manu- 
factured as follows : Into a large wooden vat or into barrels a 
quantity of iron turnings, hoops, or nails are introduced, and 
hot crude wood- vinegar, freed by distillation from wood-spirit,, 
is poured upon them. During the solution of the iron much 
tarry matter separates, which is skimmed off, and the solution, 
is frequently agitated to free it as much as possible from, the 
tar. After 24 hours the solution is drawn off. The iron* 
being entirely coated with tar so that it can not be again at- 
tacked by the wood-vinegar, it is taken from the vat and the 
tar ignited. The iron is freed from the oxide formed by 
sifting and can be again used. The solution thus obtained 
shows 13 or 14 Be. 

The pure salt is obtained by dissolving iron in acetic acid or 
by double decomposition from ferrous sulphate (14 parts) and 
lead acetate (19 parts) ; and cheaper, but less pure, from 
ferrous sulphate and calcium acetate. 

If crude calcium acetate instead of wood-vinegar is to be used 
in the preparation of this salt, a solution of the calcium acetate 
of specific gravity 1.08 is mixed with half its weight of ferrous 
sulphate dissolved in 2J times its weight of water. On agitat- 
ing the mixture, the decomposition is rendered complete, the 
clear liquor which is siphoned off after the subsidence of the 
sulphate of lime showing 13 Be. It is kept in a closed barrel 
in which is hung a bag containing a quantity of iron turnings.. 

In some factories the ferrous acetate is manufactured by de- 
composing the carbonate of iron (FeCOJ with lead acetate;: 
lead carbonate precipitates, and the blackish supernatant liquor 
is the acetate of iron in a very pure state. It is kept from ox- 


idizing by immersing in it some bright iron filings. The lead 
salt formed repays the cost of the manufacture of the acetate. 

Solution of ferrous acetate is used as a mordant by dyers, for 
staining wood and leather and in the manufacture of ink. The 
commercial article generally shows a specific gravity of 1.10 
(12 B.). 

On account of the avidity with which ferrous acetate absorbs 
oxygen, it is of great value as a reducing agent. It is, for in- 
stance, used in the preparation of aniline from nitrobenzole 
and for similar reducing processes. 

Neutral ferric acetate, sesquiacetate of iron, Fe(C 2 H 3 2 ) 3 . 
For technical use this combination is obtained by dissolving 
wrought-iron in wood-vinegar so that it has a chance to oxi- 
dize in the air. For this purpose wood-vinegar is poured over 
iron turnings in a vat, and after drawing off the solution in a 
few days, the iron is for some time left to the action of the ox- 
ygen of the air. It quickly oxidizes, and by pouring back the 
solution and several times repeating the drawing off and pour- 
ing back, a quite concentrated solution of dark red brown, 
nearly black color is in a short time obtained. Heat must 
not be employed in the preparation of this salt, as in such case 
it readily decomposes. 

Neutral ferric acetate may be obtained in the pure state by 
decomposing a solution of lead acetate by adding ferric sul- 
phate in slight excess. In the course of 24 hours the excess 
of ferric sulphate precipitates as a basic salt. It is also pro- 
duced, though more slowly, by dissolving ferric hydrate or 
ferric carbonate obtained by precipitation, in strong acetic 
acid. This method occupies more time, but affords better 
guarantees for the purity of the compound. 

By dissolving one part of nitric acid or aqua regia, precipi- 
tating the solution with ammonia and dissolving the washed 
ferric hydrate in 10 parts of acetic acid of 1.042 specific grav- 
ity, and evaporating the solution at between 140 and 17G F. 
an amorphous salt soluble in water and alcohol remains, which 
is, however, not neutral, as it contains only two instead of 3 


equivalents of acetic acid for 1 equivalent of ferric oxide. By 
dissolving this amorphous salt in acetic acid and exposing the 
dark red solution to a low temperature, the neutral salt crys- 
tallizes out in hydrated, lustrous, dark red laminse. 

On heating the strongly diluted solution of this salt to 
nearly the boiling point its color becomes more intense and it 
evolves a distinct odor of acetic acid without, however, produc- 
ing a precipitate. The salt has nevertheless become more 
basic, and an addition of any soluble sulphate or even of free 
sulphuric acid immediately precipitates the whole of the iron 
as insoluble basic ferrous sulphate. By heating, however, the 
dilute solution of the pure acetate to boiling, it disengages 
acetic acid and separates a basic salt, which, if boiling be con- 
tinued, also loses its acid so that ferric hydrate remains behind. 
The properties of this hydrate differ, however, from those of 
ordinary ferric hydrate, it dissolving in concentrated hydro- 
chloric acid only by long-continued digestion or boiling, and is 
scarcely attacked by boiling concentrated sulphuric acid. In 
acetic acid or dilute nitric acid it dissolves, however, to a red 
fluid, transparent to transmitted, but opaque to reflected, light. 
By adding the slightest quantity of a sulphate or of concen- 
trated nitric or hydrochloric acid, a granular precipitate is 
formed, which, however, redissolves on diluting the fluid with 
water. If a solution of ferric acetate is heated in a closed ves- 
sel to 212 F. for a few hours, the fluid seen by reflected light 
appears opaque and opalescent. It has also lost its metallic 
taste and no longer shows the other reactions of ferric salts, i.e., 
addition of ferrocyanide produces no precipitate nor does the 
sulphocyanide augment its red color. A trace of sulphuric 
acid or any alkaline salt suffices to precipitate the whole of the 
iron in solution as ferric hydrate, of red color, which is totally 
insoluble in all acids at an ordinary temperature ; dilute min- 
eral acids do not, however, produce a similar 'precipitate. It 
is remarkable that this ferric hydrate dissolves in water to a 
dark red fluid which can be again precipitated by concentrated 
acids or alkaline salts (Pean de St. Giles). 


From the iron acetates the iron is precipitated as black fer- 
rous sulphide by sulphuretted hydrogen. 

With ferric nitrate, ferric acetate yields a crystallizable 
double salt, Fe(C 2 H 3 2 ) 2 N0 3 + 3H 2 0, the solution of which 
decomposes on boiling, nitric and acetic acids being disengaged. 
A similar combination exists between the acetate and ferric 

Chromium acetates. Acetic acid enters into combination 
with chromous (CrO), as well as .with chromic, oxide (O 2 3 ). 
The salts are not used in the industries and are only of 
scientific interest. 

Chromous acetate, (C 2 H 3 2 ) 2 Cr + H 2 0, is prepared by mixing 
a solution of chromous chloride with sodium acetate. The salt 
separates out in small, lustrous red crystals which are sparingly 
soluble in water and alcohol, and quickly oxidize to a greater 
degree on exposure to the air, the succeeding salt being formed. 

Chromic acetate. A neutral salt is known and there are very 
likely several basic ones. The solution of the neutral salt, 
which is obtained by dissolving chromic hydrate in heated 
acetic acid, forms a red fluid, green in a reflected, and red in 
a transmitted, light. It is not decomposed by boiling, but by 
ammonia. The precipitate, however, redissolves, on adding 
ammonia in excess, to a violet-red fluid because the hydrate is 
soluble in ammonium acetate. Hence, a solution of the salt 
acidulated with acetic acid is not precipitated by ammonia. 

There are also known crystallized combinations of this salt 
with chromic chloride and sulphate and nitrate of chromium. 

If the solution of the neutral salt is for some time digested 
with chromic hydrate, it acquires a darker color, the acid 
reaction disappears, and on evaporating, a green powder 
soluble in water remains behind. Ordway has described a 
purple busic salt. 

Nickel acetate forms small green crystals soluble in water, 
but not in alcohol. 

Cobalt acetate forms small red crystals, the concentrated 
solution of which turns blue on heating but again red on cool- 
ing, and can, therefore, be used as sympathetic ink. 


Zinc acetate, Zn(C 2 H 3 2 ) 2 . This salt may be prepared by 
dissolving metallic zinc, zinc oxide or zinc carbonate in acetic 
acid, or by the decomposition of zinc sulphate by acetates of 
lime or lead similar to the acetate of manganese. The acetate 
is in the first three instances simply obtained by evaporation, 
and in the latter, after agitating the mixture, filtering and 
evaporating the filtrate. The salt crystallizes in flexible, opal- 
escent, six-sided tables which effloresce slightly in the air. 
Technically the best receipt is to dissolve 4 parts of the sul- 
phate of zinc and 7J parts of acetate of lead each in 3 parts- 
of hot water, mixing the solutions, agitating, and after the 
sulphate of lead has deposited, drawing the clear liquid off to- 

Copper acetates. Cuprous acetate, Ca 2 (C 2 H 3 2 ) 2 . This salt is- 
produced by subjecting crystallized verdigris to dry distillation. 
It is a white substance crystallizing in fine needles, which are 
decomposed by water into yellow cuprous hydrate and cupric 

With cupric oxide acetic acid forms a normal and several 
basic salts. 

Neutral cupric acetate; crystallized verdigris, Cu(C 2 H 3 2 ) 2 . 
The normal cupric acetate may be prepared by dissolving 
pure cupric oxide or cupric hydrate in pure acetic acid or by 
employing, instead of the pure oxide, copper scales whose con- 
tent of metallic copper and of cuprous oxide is converted into 
cupric oxide by moistening with nitric acid and gentle glow- 
ing. The cupric oxide thus obtained .is washed to remove 
foreign substances. The conversion of the cuprous oxide into 
cupric oxide is especially essential when the acetic acid is not 
entirely free from hydrochloric acid, as otherwise cuprous- 
chloride is formed which dissolves with difficulty. 

If copper scales cannot be obtained, hydrated basic carbon- 
ate of copper can be prepared by precipitating sulphate of 
copper with soda, and, after washing and pressing, dissolving 
in acetic acid. Sulphate of soda remains dissolved in the 
water, and this solution can eventually be utilized for the 


conversion of crude calcium acetate into sodium salt. Instead 
of soda, milk of lime can also be used for the decomposition 
of the sulphate of copper, a mixture of calcium sulphate and 
cupric hydrate being precipitated. By adding acetic acid the 
latter is redissolved while the calcium sulphate remains sus- 
pended. When the latter has settled the solution is drawn off 
and evaporated. The calcium sulphate is repeatedly washed 
with small portions of water, and the wash-waters are used for 
dissolving fresh quantities of sulphate of copper. 

In case the sulphate of copper contains iron, the latter is re- 
moved by digesting the solution for several days with basic 
carbonate of copper. The presence of iron is recognized by 
the sulphate not dissolving entirely in ammonia in excess, but 
leaving behind a red-brown residue (ferric hydrate). 

The neutral acetate can also be prepared by dissolving the 
basic salt, verdigris (described below), in acetic acid. The so- 
lution is filtered and evaporated until a crystalline film is 
formed. This method is, however, expensive. 

The method by double decomposition may be recommended 
for preparing the neutral acetate on a small scale, but not for 
manufacturing purposes. Sulphate of copper (125 parts) and 
sodium acetate (136 parts) decompose each other, neutral 
cupric acetate crystalizing out, while sodium sulphate remains 
in solution. The yield is, however, somewhat smaller than 
theoretically might be expected, because the sulphate of cop- 
per is not entirely insoluble in sodium sulphate solution. By 
this process the object is quickly accomplished, and for this 
reason is decidedly to be preferred to the following : Sulphate 
of copper (125 parts) and normal lead acetate (190 parts) 
decompose completely only in dilute, but not in concentrated, 
solutions. Hence strong evaporation is required, whereby 
acetic acid is lost. Further, with the use of lead acetate some 
of the newly-formed lead sulphate is obtained in solution ; but 
the lead cannot be separated with sulphuretted hydrogen 
because the latter would also decompose the copper salt. The 
disadvantage of substituting calcium acetate for the lead ace- 


tate is that it is not crystallized and hence furnishes no exter- 
nal criterion of purity ; in fact it always varies slightly in 
composition. If a small excess of calcium salt has been used, 
the latter, after the calcium sulphate is filtered off and the 
solution evaporated, does not remain in the mother lye, but 
crystallizes out as double salt (see below), together with the 
copper salt. Since these acetates create difficulties, and as 
each of them must first be prepared by the manufacturer by 
means of acetic acid, it would seem more rational to directly 
use this acetic acid for dissolving the cupric oxide, whereby 
no by-products of little value, such as sulphate of lead, calcium 
and sodium, are formed. 

The evaporation of the solution of cupric acetate obtained 
by any of the above methods is effected in a copper boiler over 
an open fire, or, still better, by steam. It is recommended to 
close the boiler so that the escaping vapors of water and acetic 
acid are condensed in a worm. Independently of the fact that 
by these means the escaping acetic acid is regained and can be 
used for other purposes, a great advantage is that the air of 
the workroom is thereby not contaminated by flying particles 
of salt. 

Crystallization is generally effected in stoneware pots into 
which dip a number of slender wooden rods. The pots are 
placed in a warm room. Crystallization is finished in about 14 
days. The crystals turn out especially beautiful when the acid 
somewhat preponderates and the solution is cooled very slowly. 

The salt forms dark green * rhombic prisms of a nauseous 
metallic taste, which dissolve in 14 parts of cold, and 5 parts 
of boiling, water; and are also soluble in alcohol. Heated in 
the air the crystals burn with a green flame. 

Neutral cupric acetate contains in 100 parts: Cupric oxide 
39.8, anhydrous acetic acid 51.1, water 9. 

On heating, the dilute solution of the neutral salt yields 

* There is also another salt of a beautiful blue color, which contains, however, 
o equivalents of water (VVohler). It is prepared by exposing a solution of the salt 
mixed with free acetic acid to a low temperature. At 95 F. it passes into the 
ordinary green salt. 


acetic acid and deposits a basic salt ; hence the use of strongly 
diluted acetic acid or even distilled vinegar is not suitable for 
the preparation of crystallized verdigris. By long-continued 
digestion with freshly glowed charcoal the dilute solution 
yields its entire content of copper to the latter ; hence vinegar 
containing copper can be purified in this manner (2 or 3 per 
cent, of charcoal being sufficient). The crystals of normal 
cupric acetate, after drying in vacuo, lose more water at 212 
F., but give off 9 per cent, of their water between 230 and 
284 F. By destructive distillation cupric acetate yields strong 
acetic acid which contains acetone and is contaminated with 
copper. Cuprous oxide (Cu 2 0) is obtained in red octahedral 
crystals when the neutral salt is heated with organic substances, 
such as sugar, honey, starch, etc. With the acetates of potas- 
sium, sodium, and calcium, normal cupric acetate gives double 
salts of a vivid blue color, which form fine crystals. 

The chief use of normal cupric acetate in the arts is in 
making pigments and for resisting the blue color which the 
indigo would communicate in the indigo bath of the calico 
printer. In the latter case its mode of action depends on the 
readiness with which it parts with oxygen, whereby the indigo 
is oxidized before it can exert any action on the cloth, being 
itself reduced to the state of acetate of suboxide of copper. 
Crystallized verdigris is occasionally employed as a transparent 
green water color or wash for tinting maps. In medicine it 
is used for external application. It is poisonous, like all 
soluble copper salts. 

Basic cupric acetates. Sesquibasic cupric acetate (Cu(C 2 H 3 2 ) 2 ). 
CuO-f- 6H 2 0. This compound is obtained pure by gradually 
adding ammonia to a boiling concentrated solution of the nor- 
mal acetate until the precipitate, which is at first formed, is 
redissolved. As the liquor cools the new salt then crystallizes 
out in beautiful blue-green scales, which at 212 F. lose 10.8 
per cent, of their water. Their aqueous solution is decom. 
posed by boiling, acetic acid being given off and the black 
oxide of copper precipitated. 


Dibasic cupric acetate, Cu(C 2 H 3 2 ) 2 CuO-|-6H 2 0, constitutes 
the greater part of the blue variety of verdigris. It forms 
beautiful, delicate, blue, crystalline needles and scales, which 
when ground form a fine blue powder. When heated to 140 
F. they lose 23.45 per cent, of water and become transformed 
into a beautiful green, a mixture composed of the neutral and 
tribasic acetates. By repeated exhaustion with water the 
dibasic, is resolved into the insoluble tribasic, salt, and a solu- 
tion of the normal and sesquibasic cupric acetates. 

Tribasic cupric acetate, Cu(C 2 H 3 2 ) 2 2CuO+3H 2 0. This corn- 
pound is the most stable of all of the acetates of copper. It is 
prepared by boiling the aqueous solution of the neutral acetate, 
by heating it with alcohol, by digesting its aqueous solution 
with cupric hydrate, or by exhausting blue verdigris with 
water as above mentioned. The first methods yield the salt 
in the form of a bluish powder composed of needles and scales, 
the last as a bright green powder. This salt yields all its 
water at 352 F. ; at a higher temperature it decomposes and 
evolves acetic acid. Boiling water decomposes the solid triba- 
sic acetate into a brown mixture of the same salt with cupric 

Under the name of verdigris two varieties of basic cupric 
acetates are found in commerce: French verdigris which occurs 
in globular, bluish-green, crystalline masses, but also in amor- 
phous masses, and English verdigris of a pure green color and 
crystalline structure, which is, however, also manufactured in 
Germany and Sweden. 

The first variety is chiefly manufactured in the region around 
Montpellier, France. The refuse of grapes, after the extraction 
of the juice, is placed in casks until acetous fermentation takes 
place. The casks or vessels are covered with matting to pro- 
tect them from dirt. At the end of two or three days the fer- 
menting materials are removed to other vessels in order to 
check the process, to prevent putrefaction. The limit to which 
fermentation should be carried is known by introducing a test- 
sheet of copper into the mass for 24 hours; if, on withdrawing 


it at the end of that time, it is found covered with a uniform 
green coating, the proper degree of fermentation has been 

Sheets of copper are prepared by hammering bars of the 
metal to the thickness of about ^ of an inch (the more com- 
pact the copper sheets the better), and they are then cut into 
pieces of 6 or 8 inches long by 3 to 4 broad. Sometimes old 
ship-sheathing is used and cut into pieces of the required size. 
The sheets are immersed in a concentrated solution of verdegris 
and allowed to dry. When the materials are all found to be 
in proper condition, the copper sheets are laid on a horizontal 
wooden grating in the middle of a vat, on the bottom of which 
is placed a pan of burning charcoal, which heats them to about 
200 F. In this state they are put into large stoneware jars 
with alternate layers of the fermenting grape lees ; the vessels 
are covered with straw mats and left at rest. At the end of 10 
to 20 days they are opened to ascertain if the operation is 
complete. If the upper layer of the lees appears whitish and 
the whole has worked favorably, the sheets will be covered 
with silky crystals of a green color. The sheets are then taken 
from the jars and placed upright in a cellar, one against the 
other. At the end of two or three days they are moistened 
with water and again placed to dry. The moistening with 
water is continued at regular intervals of a week for six or eight 
times. This treatment causes the sheets to swell and become 
incrusted with increased coatings of the copper salt, which are 
detached from the remainder of the sheets by a copper knife. 
The scraped plates are submitted to a fresh treatment till the 
whole of the copper is converted into verdigris. The salt 
scraped off is made into a consistent paste by kneading with a 
little water, and in this state is packed into leathern bags which 
are placed in the sun to dry until the mass hardens and forms 
the tough substance which constitutes the commercial article. 

In England, Germany and Sweden copper sheets are moist- 
ened with a solution of verdigris in vinegar and placed in a 
warm room, or woollen cloths moistened with the above solu- 


tion are used, which are placed alternately with the copper 
sheets in a square wooden box. The woollen cloths are moist- 
ened with the solution every three days for 12 or 15 days, 
when small crystals commence to form on the sheets. The 
sheets are then drawn every six days through water and re- 
placed in the box, but not in direct contact with the woollen 
cloths, small disks of copper or small pieces of wood being 
placed between each cloth and sheet. The woollen cloths are 
now more thoroughly saturated than before, but with a weakei 
solution. With a temperature of from 54 to 59 F., 6 to 8 
weeks are required before the verdigris can be scraped off. 
The product is not identical with that obtained by the French 
method, it being somewhat poorer in acetic acid, and hence its 
color is not bluish-green, but almost pure green. 

Lead Acetates. With plumbic oxide acetic acid gives a 
neutral, as well as several basic, salts. The most important of 
these combinations are the neutral salt, known in commerce 
as sugar of lead, and a basic salt by means of which white 
lead is obtained. 

Neutral Acetate of Lead (Sugar of Lead), Pb(C 2 H 3 2 ) 2 +3HO. 
According to Volkel's method, acetic acid prepared from 
wood-vinegar and rectified over potassium dichromate is satu- 
rated with litharge, filtered or decanted, and after a further 
addition of acetic acid until a slightly acid reaction takes place, 
evaporated to the crystallizing point. 

By saturating acetic acid with litharge, a solution of basic 
salt is obtained, which is later on converted into neutral salt 
by the addition of acetic acid. This is more suitable than 
using only as much litharge as the acetic acid requires for 
the formation of the neutral salt, because the litharge dis- 
solves with greater ease in solution of sugar of lead than in 
acetic acid. 

Solution of sugar of lead, like solution of neutral cupric ace- 
tate, permits of the evaporation of acetic acid in boiling ; and, 
hence, it is best to use strong acetic acid, because less will have 
to be evaporated and the loss of acetic acid be consequently 


smaller. By taking, for instance, acetic acid of 1.057 specific 
gravity, for 100 Ibs. of it 82 Ibs. of litharge are required for the 
formation of the neutral salt. A larger quantity is, however, 
taken (from 100 to 180 Ibs.), so that a basic salt is formed, or, 
with 100 Ibs., a mixture of neutral and basic salts. To recog- 
nize the point of neutralization in the subsequent addition of 
acetic acid, litmus paper is used, or, still better, dilute solution 
of corrosive sublimate (1 part of corrosive sublimate in 100 of 
water), which does not change the neutral salt, but produces 
turbidity in the basic (Buchner). Hence, by from time to 
time testing the lead solution with this reagent, the point of 
neutralization is reached the moment turbidity ceases. This 
test is better than with litmus, considerable experience being 
required to hit the right point with the latter on account of 
solution of sugar of lead showing a slight, but perceptible acid 

The solution of litharge in acetic acid is promoted by heat, 
and is effected either in a copper pan, the bottom and sides of 
which are brought in contact with a few bright sheets of lead 
(to prevent the copper from being attacked), or in a lead pan 
over an open fire, or in a wooden vat into which steam is in- 
troduced. The clear solution is evaporated. If this is to be 
done over an open fire, it is recommended to have a prepara- 
tory heating pan for each evaporating pan, as described in the 
preparation of calcium acetate, the preparatory heating pan, 
which is heated by the escaping gases, being used for the solu- 
tion of the litharge in acetic acid. Lead pans, if used, should 
rest upon strong cast-iron plates. The dimensions of the pans 
vary very much. According to Assmus, they are 6J feet long, 
4 feet wide, and from 12 to 14 inches deep, while the depth 
of the preparatory heating pans is from 24 to 28 inches. From 
the latter, which stand at a higher level, the clear solution is 
discharged, through a stop-cock just above the bottom, into 
the evaporating pans. Evaporation should be effected at a 
moderate heat; actual boiling must be strictly avoided, as 
otherwise large losses of acetic acid are unavoidable and the 
solution readily acquires a yellow coloration. 


According to the degree of evaporation (to 36 B. or to 46 
B. or more) of the sugar of lead solution, distinct crystals are 
obtained or only a radiated crystalline mass. With a perfectly 
pure solution the first method is the best, since crystals bring 
a better price. The mother-lye, after being again acetified, is 
once more evaporated and acetified and yields more crystals. 

Stein recommends the conducting of the vapors of acetic 
acid or of vinegar into litharge mixed with a very small quan- 
tity of water. This method is in general use in Germany. But 
as the extract remaining iri-the still retains a considerable 
quantity of acetic acid, especially if beer had been added to the 
liquid used in the preparation of the vinegar, it is advisable to 
increase the boiling point of the latter by the addition of one- 
third of its weight of common or rock salt. At first the water 
condenses in the receiver and the volume of the fluid containing 
the litharge increases, but when the boiling point is reached in 
the condensing vessels, only the acetic acid is retained, while 
the litharge is first converted into sexbasic and then into tri- 
basic acetate. To obtain neutral salt, however, either the 
vapors must be somewhat expanded or several condensing 
vessels be placed one after the other. 

Fig. 84 shows the distilling apparatus, consisting of a still, 
a, of sheet-copper. The vapors pass through a copper pipe, 5, 
into the wooden vat, c, lined with lead, and about 35 inches 
in diameter and (>7 inches deep. In this vat are four bottoms, 
d, of thick lead provided with fine perforations. Short lead 
pipes, soldered into these bottoms and arranged as shown in 
the figure, serve to conduct the vinegar vapors in the vat to 
and fro in the interspaces between the lead bottoms. For each 
still at least three of such vats are connected with each other. 
Upon the lead bottoms is first placed a layer of linen or of 
flannel, and next a layer of litharge 2 to 4 inches deep. To 
prevent the litharge from packing, it is mixed with an equal 
volume of pebbles, about the size of a pea. The vats are pro- 
vided with lids of sheet-copper lined with lead. From the lid 
of the last vat a pipe leads to a worm surrounded with cold 


water. The stop-cocks on the bottoms of the vats permit the 
discharge of the collected lead solution, which is effected (with 
the use of acetic acid) when it shows a specific gravity of at 
at least 36 Be. The solution being, however, basic, it is aceti- 
fied with strong acetic acid, and brought into the crystallizing 


This method is decidedly the best, because the evaporation 
of the solution is entirely or almost entirely omitted and the 
air of the workroom is not contaminated by particles of sugar 
of lead, which is very injurious "to the health of the workmen. 

FIG. 84. 

Furthermore, this taethod does not require the use of pure 
acetic acid, since the impurities remain in the still. This, how- 
ever, holds good only for non-volatile impurities. For the 
production of colorless salt, the crude acetic acid from wood- 
vinegar must necessarily be purified, as above mentioned, 
by potassium chromate and sulphuric acid. 

The crystallizing pans are either of stone-ware or of wood 
lined with lead or thin copper, to which is soldered a strip of 
lead down the sides and across the bottom, with the idea of 
rendering the metal more electro-negative, so as to prevent the 



acetic acid from acting on it. The wooden crystallizing pans 
are about 4 feet long by 2 feet wide, and from G to 8 Indies 
deep, sloping inwards at the edges. Shallow, slightly conical 
copper vessels. 6 inches deep, with a diameter of 29J inches 
at the bottom and 31 J inches at the top, are also used. The 
stone-ware pans are placed upon a slightly inclined level cov- 
ered with lead. In these small pans crystallization is complete 
in 24 hours, while from 48 to 72 hours are required with the 
use of the larger wooden vessels. Crystallization being com- 
plete, the mother-lye is removed, and the vessels are placed 
upon a wooden frame over a gutter of sheet-lead to drain off, 
as shown in Figs. 85 and 8G. 

FIG. 85. 

FIG. 86. 

If especially beautiful crystals are to be obtained, the first 
crystals, which are not very distinct, are again dissolved in 
the water obtained by the condensation of the vapors escaping 
from the still. The solution being evaporated to the proper 
density is again allowed to crystallize. The crystals, after 
sufficient drainage, are placed upon linen spread over wooden 
hurdles and dried at a moderate heat, not exceeding 75 F. 
In some factories the heated air of a stove, placed outside the 
drying-house, is conveyed through pipes passing round the 
interior; at other places steam heat is employed for this pur- 
pose, which is much to be preferred, on account of its being 
more easily regulated. 

When working on a large scale a centrifugal is advantage- 
ously employed for the separation of the mother-lye, in the 


same manner as recommended for the preparation of sodium 

Litharge being a quite impure lead oxide never dissolves 
entirely, and frequently contains over 10 per cent, of impuri- 
ties, consisting of sand, clay, red lead or minium (Pb 3 4 ), 
metallic lead, traces of silver, cupric and ferric oxides. The 
cupric oxide passes into the sugar of lead solution and colors 
it slightly blue. To separate the copper, bright sheets of lead 
are dipped into the solution, the copper separating upon them 
in the form of a dark slime. The sheets of lead must be fre- 
quently cleansed (scraped), as otherwise they lose their effect. 
When there is a large accumulation of litharge residue, it can 
be worked for silver. 

Sugar of lead can also be prepared from metallic lead, the 
process having been recommended first by Berard, and is said 
by Runge to yield a good product with great economy. Gran- 
ulated lead, the tailings in the white lead manufacture, etc., 
are put in several vessels, say eight, one above the other, upon 
steps, so that the liquid may be run from one to the other. 
The upper one is filled with acetic acid, and after half an hour 
let off into the second, after another half hour into the third, 
and so on to the last or eighth vessel. The acid causes the 
lead to absorb oxygen so rapidly from the air as to become 
hot. When the acid runs off from the lowest, it is thrown on 
the uppermost, vessel a second time and carries off the acetate 
of lead formed. After passing through the whole series the 
solution is so strong that it may be evaporated at once so as to 

Apparently this method has a considerable advantage over 
that with litharge, metallic lead being cheaper and producing 
more sugar of lead (entirely free from copper) than litharge, 
because 103.5 Ibs. of pure lead yield 189.5 Ibs. of sugar of lead, 
while the same quantity is only obtained from 111.5 Ibs. of pure 
litharge. Furthermore, commercial lead is always purer than 
litharge. On the other hand, this process has the disadvan- 
tage of a considerable quantity of acetic acid being lost by 


evaporation on account of it having to pass through several 
vessels. The manufacture of sugar of lead is most suitably 
combined with that of white lead, it being thus possible to 
utilize the tailings, etc., to greater advantage than, as is fre- 
quently done, by melting them together and remelting, which 
always causes considerable loss. 

Sugar of lead is further formed by boiling lead sulphate 
with a very concentrated solution of barium acetate, barium 
sulphate (permanent white) being thereby precipitated. For 
100 parts of lead sulphate 84 parts of anhydrous or 100 of 
crystallized barium acetate are required, the yield being 125 
parts of sugar of lead. Sulphate of lead is obtained in large 
quantities as a by-product in the preparation of aluminium 

For many purposes of dyeing and printing the use of pure 
sugar of lead is not necessary, the brown acetate of lead an- 
swering all requirements. For its preparation ground litharge 
is introduced in small portions, stirring constantly, into dis- 
tilled wood vinegar in a vat until red litmus paper is colored 
blue, and, hence, a basic salt is formed. The impurities sep- 
arating on the surface are removed and the clear fluid is then 
transferred to a copper pan equipped with strips of lead, and is 
evaporated to about two-thirds its volume, the brown smeary 
substances rising to the surface during evaporation being con- 
stantly removed. By again diluting and slightly acidulating 
the concentrated fluid a further portion of the foreign sub- 
stances can be removed. Finally evaporation is carried to 
the crystallizing point, i. e., until a few drops congeal when 
allowed to fall upon a cold metal plate. The addition of 
animal charcoal for the purpose of discoloration is of no ad- 
vantage. The coloration is not completely removed, and the 
little effect produced is attained at a considerable loss of salt, 
which is absorbed by the animal charcoal. 
. By disturbing crystallization by constant stirring during 
cooling, a nearly amorphous mass, having the appearance of 
yellow wax, is obtained, which is much liked by many con- 


sutners. The product thus obtained is not always a neutral 
salt, but sometimes a mixture of neutral and basic salts (be- 
sides empyreumatic substances). After cooling it must, there- 
fore, be quickly and well packed, in order to protect it from the 
moisture and the carbonic acid of the air. The sugar of lead 
solution may, however, also be evaporated only so far that 
some mother-lye remains after cooling, the crystallized mass 
being then for some time allowed to stand in a moderately 
warm room. In consequence of capillarity, the impurities, 
which occur chiefly in the mother-lye, gradually rise up be- 
tween the crystals, a slight coating of yellow, or brown, smeary 
substance being finally formed upon the mass of crystals, 
which can be readily removed. 

The linen upon which the crystals are dried must be care- 
fully protected from fire, as it ignites from the slightest spark 
and burns like tinder. 

If the hot solution be set aside to cool rapidly, the sugar of 
lead crystallizes in clusters of fine needles ; but if evaporation 
be conducted slowly the crystals are truncated and flattened, 
quadrangular and hexahedral prisms derived from a right 
rhombic prism. Acetate of lead has a sweet astringent taste, 
is soluble in 1 J parts of water and in 8 parts of ordinary alco- 
hol. The crystals are permanent in the atmosphere, but are 
apt to effloresce and become anhydrous if the temperature 
ranges between 70 and 100 F. 

Acetate of lead consists of: 

Plumbic oxide 58.9 

Anhydrous acetic acid 26.9 

Water . . . 14.2 


Aqueous solution of sugar of lead slightly reddens litmus- 
paper, but shows an alkaline reaction upon turmeric, brown- 
ing it. 

At 167 F. the crystals of acetate of lead melt, and slowly 
yield up their water ; by heating the entirely dephlegmated 


salt more strongly it fuses at 536 F. to a clear, oil-like, color- 
less fluid and decomposes above this temperature, evolving all 
the compounds usually obtained in the destructive distillation 
of the acetates of the heavy metals, while a residue of metallic 
lead in a very minute state of division, with some charcoal, is 
left behind. When this distillation is conducted in a glass 
tube closed at one end and having the other drawn out for 
convenience of sealing at the end of the operation, the well- 
known lead pyrophorous is made. The particles of metallic 
lead are so small that, when thrown into the air, oxygen mole- 
cules come into such intimate contact with them that ignition 
is effected from the rapidity with which lead oxide is formed. 

A slight decomposition occurs when the neutral salt is ex- 
posed to an atmosphere of carbonic acid, carbonate of lead 
being formed ; the portion of acetic acid thus liberated pro- 
tects the remainder from further change. 

Cold solution of sugar of lead is not immediately changed 
by ammonia ; by adding, however, a large excess of it, sexbasic 
acetate of lead is gradually separated ; on boiling, yellow-red 
crystalline lead oxide is precipitated. 

The introduction of chlorine gas into a solution of sugar of 
lead produces in a short time a brown precipitate of plumbic 
dioxide. Bromine acts in a similar manner, but on account 
of its insolubility, iodine produces scarcely any effect. 

Solution of calcium chloride at once produces a yellow 
precipitate, which gradually becomes brown. 

Sugar of lead containing considerable copper has a bluish 
appearance. If the content of copper is small, it is recognized 
by the solution acquiring with ammonia a blue coloration, or, 
still better, by mixing the solution of sugar of lead with an ex- 
cess of solution of Glauber's salt and testing the filtrate with 
potassium, ferrocyanide. A dark-red precipitate indicates 

Sugar of lead, as well as the basic lead salts to be men- 
tioned further on, possesses poisonous properties. 

Sugar of lead is chiefly used for the preparation of alum- 


inium acetate, as well as of other acetates. Considerable 
quantities of it are consumed in the manufacture of colors, for 
instance, of neutral and basic lead chromate, chrome yellow, 
chrome orange, and chrome red. Upon the cloth-fibre (espec- 
ially wool) chrome yellow and chrome orange are produced 
by means of sugar of lead, particularly with the brown variety ; 
the latter product being also very suitable for the production 
of the so-called chrome green, which is obtained by the joint 
precipitation of chrome yellow and Berlin blue. 

Neutral lead acetate gives crystallizable double salts with 
potassium acetate and sodium acetate as well as with lead 
nitrate, lead chloride, lead bromide, etc. 

Basic lead acetates. Several of these compounds are known. 
Those with 2 and 3 equivalents of lead oxide to 1 equivalent 
of acetic acid are soluble in water, show a strong alkaline reac- 
tion, and with carbonic acid the solutions yield at once and 
in every degree of concentration, abundant precipitates of 
white lead (basic carbonate of lead), while, when the operation 
is at a suitable moment interrupted, neutral salt remains in 
solution. In this manner white lead is manufactured accord- 
ing to the so-called French method (of Thenard and Hoard) 
at Clichy and other places in France, as well as in different 
German factories. If however, the introduction of carbonic 
acid be continued until no more precipitate is formed, a part 
of the lead of the neutral salt is also precipitated as carbonate, 
which, however, is neutral, and an acid solution remains 

The soluble salt known as lead vinegar or extract of lead is 
prepared by digesting 2 parts of sugar of lead dissolved in 5 
of water with 1 of finely powdered litharge. The propor- 
tional quantities of sugar of lead, litharge and water prescribed 
by the Pharmacopoeias of the different countries vary very 
much, and, consequently, also, the compositions and specific 
gravities (from 1.20 to 1.36) of the solutions of lead prepared 
in accordance with them. The litharge dissolves very readily 
in the sugar of lead solution, in fact with greater ease than in 


acetic acid, and especially with greater rapidity if the sugar of 
lead solution be heated in a silver dish to the boiling point 
and the litharge gradually introduced. For the manufacture 
on a large scale, the sugar of lead solution and the litharge 
may be brought into a barrel revolving around its axis. If 
the operation is to be conducted at the ordinary temperature, 
the barrel must be closed to prevent the access of the car- 
bonic acid of the air. Very remarkable is the behavior of the 
tribasic acetate towards hydrogen dioxide ; plumbic dioxide 
being first formed. But in a short time this exerts a decom- 
posing influence upon the hydrogen dioxide which may be 
present in excess, so that both dioxides' now lose one-half of 
their oxygen, which evolves in the form of gas, and water 
and plumbic oxide are formed.* Now, as freshly precipitated 
plumbic dioxide possesses the further property of decomposing 
solution of potassium iodide, Schoenbein recommends tribasic 
acetate of lead, together with paper coated with paste prepared 
with potassium iodide, as the most sensitive reagent for hydro- 
gen dioxide. 

Lead Sesquibasic Acetate, Triplumbic Tetracetate. This salt is 
obtained by heating the diacetate until it becomes a white, 
porous mass ; this is redissolved in water and set aside to 
crystallize. Sesquibasic acetate is soluble in both water and 
alcohol ; its solutions are alkaline. 

Tribasic acetate of lead is prepared by digesting 189.5 Ibs. of 
sugar of lead with 223 Ibs. of plumbic oxide (pure) or 3 Ibs. 
of sugar of lead to 4 Ibs. of litharge ; or, according to Payen, 
into 100 volumes of boiling water are poured 100 volumes of 
aqueous solution of sugar of lead saturated at 86 F., and 
afterwards a mixture of pure water at 140 F., with 20 volumes 
of ammonia liquor free from carbonate. The vessel is then 
immediately closed, and in a short time an abundance of the 
tribasic acetate crystallizes out. The salt presents itself under 
the form of long needles. It is insoluble in alcohol, very solu- 

* Schoenbein in Wagner's Jahresbericht, 1862. 


ble in water, its solution being alkaline. Tribasic acetate is 
the most stable of all the subacetates of lead. It takes a lead- 
ing part in the manufacture of white lead by the Clichy pro- 
cess. It is, in point of fact, a solution of this salt, which is 
decomposed by the carbonic acid, and gives rise to the carbon- 
ate of lead, being itself at the same time converted into lead 
diacetate. In the Dutch process the formation of lead carbon- 
ate is, according to Pelouze, also due to the formation of tri- 
basic acetate on the surface of the sheets of lead, which is, in 
its turn, decomposed by the carbonic acid. 

Sexbasic Acetate of Lead. This body is prepared by digest- 
ing any of the preceding salts with lead oxide. It is a white 
powder slightly soluble in boiling water, from which it crys- 
tallizes out in silky needles which consist of two equivalents 
of the salt combined with three equivalents of water. 

Uranium Acetate. With uranous oxide, acetic acid combines 
to a dark green crystallizable salt, and with uranic oxide to a 
yellow basic salt, which, combined with water, appears in two 
different forms of crystals. It is remarkable for giving, with 
many other acetates, well crystallizing salts, of a beautiful 
color, and partly showing magnificent dichroism (Wertheim 
and Weselsky). 

Tin acetate is prepared by dissolving stannous hydrate * in 
heated strong acetic acid, or by mixing stannous chloride 
(SnCl 2 ) with acetate of sodium or calcium. It forms small 
colorless needles, which have a strong metallic taste and 
readily decompose in the air. The salt is used to discharge 
azo-dyestuffs in calico printing. 

Bismuth Acetate. Bismuth nitrate prepared by gradually 
introducing pulverized metallic bismuth into cold dilute nitric 
acid is mixed with pure concentrated sugar of lead solution. 
The salt separates in small, colorless needles. 

Mercurous acetate can be prepared by dissolving pure mer- 

*The hydrate is obtained by precipitating stannous chloride with soda lye and 
washing the precipitate. 


curous oxide or its carbonate in acetic acid, or by mingling 
hot solutions of mercurous nitrate and acetate of sodium or of 
potassium. The pure mercurous carbonate is heated to boiling 
with 8 parts of water, and concentrated acetic acid added until 
all is dissolved ; the hot, filtered liquid free from oxide being 
allowed to cool. Or, acidulated nitrate is diluted with 6 to 8 
parts of water, heated and mixed with one equivalent of acetate 
of sodium or potassium, dissolved in 8 parts hot water con- 
taining a little free acid, and cooled. The salt, when sepa- 
rated, is washed with a little cold water, dried in the dark at 
a gentle heat, and kept from the light in covered bottles. 

It crystallizes in fine, white, silvery scales, flexible and unc- 
tuous to the touch, with a nauseous metallic taste, easily de- 
composed by light. It dissolves with difficulty in cold water, 
requiring 33 parts at the ordinary temperature. It is par- 
tially decomposed by boiling water into acid and basic salts of 
both oxides and metallic mercury. It is used in pharmacy. 

Mercuric Acetate. Dissolve red oxide of mercury in concen- 
trated acetic acid at a gentle heat and evaporate to dry ness, 
or partially to crystallization, or by spontaneous evaporation. 
When obtained by the first process it is a white saline mass ; 
by the second it forms crystalline scales; and by the third, 
four-sided plates, which are partly transparent, partly pearly 
and translucent, anhydrous, of a nauseous metallic taste, fusi- 
ble without decomposition, solidifying to a granular mass, but 
the point of decomposition of the latter is near that of fusion. 
It dissolves in 4 parts of water at 50 F., in 2.75 at 66.2 F., 
and in 1 at 212, but by boiling it is partly decomposed, 
red oxide being separated. Even in the air its solution suf- 
fers the latter change and contains a basic salt. With free 
acetic acid it is not decomposed. One hundred parts of alco- 
hol dissolve 5f of this salt, and this solution behaves like the 
aqueous one. It generally contains, except when carefully 
crystallized, some mercurous oxide. 

Silver Acetate. This salt is obtained by precipitating a con- 
centrated solution of silver nitrate with a concentrated solution 


of sodium acetate. It forms a white crystalline precipitate. 
ft dissolves in about 100 parts of cold, but readily in hot, 
water, and only sparingly in alcohol. On exposure to light it 
acquires a dark color, being partially reduced. On heating, 
it yields acetic acid, metallic silver remaining behind. 

If the salt be heated with disulphide of carbon in a closed 
glass tube to 329 F., silver sulphide, carbonic acid and anhy- 
drous acetic acid are formed (Broughton). 

On treating the dry salt with iodine, lively decomposition 
takes place, whereby silver iodide, some metallic silver and coal 
remain behind, while methyl oxide, acetic acid, acetylene and 
hydrogen appear. With iodine a solution of this salt yields 
acetic acid, silver iodide and iodate of silver (Birnbaum). 



Preparation of Wood Spirit. The crude wood-spirit solu- 
tions collected during the distillation of the wood vinegar 
contain, according to their method of production, from 9 to 10 
per cent, wood spirit. They are subjected to repeated distil- 
lation and rectification over milk of lime to fix the acetic acid 
present and to saponify the methyl acetate. In this manner 
wood spirit is produced, i. e. } a mixture that besides methyl 
alcohol contains other combinations such as aldehyde, methyl- 
acetic ether, acetone and similar combinations, amines, higher 
alcohols, etc. 

The crude wood-spirit of commerce contains besides the 
above-mentioned constituents. 75 per cent, of methyl alcohol. 
It is clear as water to dark brown and can be mixed in every 
proportion with water without becoming turbid. 

Wood spirit for denaturing purposes is produced from the 


crude wood spirit by further rectification. It contains 95 per 
cent, methyl alcohol, and while the higher alcohols and the 
acetone have been removed, aldehyde, methyl acetate, etc., 
are still present. 

Pure wood spirit contains 98 to 99.5 per cent, wood-spirit 
constituents, among which methyl alcohol, however, pre- 
ponderates so that they are almost entirely pure. Such pure 
wood spirit contains only very small quantities of acetone 
0.01 to 0.5 per cent. It does not discolor bromide solution 
and when mixed with concentrated sulphuric acid acquires an 
only slightly yellower color. 

The rectification of the crude wood-spirit solutions collected 
during the distillation of the wood vinegar is effected in a 
columnar still. The crude wood-spirit solution is brought 
into the still and, after adding slaked lime, the fluid is allowed 
to rest for several hours. After the addition of the lime the 
fluid soon becomes strongly heated in consequence of the free 
acids combining with the lime, and of the formation of cal- 
cium acetate and methyl alcohol from the methyl acetic ether, 
small quantities of ammonia being also evolved. 

After having rested for several hours the fluid is subjected 
to distillation. In Fig. 87, a represents the copper still, b an 
ellipsoidal or egg-shaped vessel which serves as a receiver, and 
c the rectifying apparatus, consisting of a series of Pistorius's 
basins into the uppermost of which a moderate current of 
water is conducted ; d is the condenser. 

The still a has a capacity of 1000 to 1200 quarts ; the steam 
pipe placed in it is 2 inches in diameter and 32 feet long. 
The vapors pass out through the wide pipe in the cover, and 
what is condensed in b runs back through a narrower pipe 
into a. In the rectifying vessel or rather dephlegmator, the ris- 
ing vapors are forced to pass around a copper disk placed in 
each basin, and thus to come in contact with the surface of 
the basin cooled by water. From this it is evident that the 
less volatile bodies are condensed in the basins and run back 
into b and from there into a, while the more volatile vapors 



pass through the swan-neck and are condensed in d. Much, 
of course, depends on the quantity (and temperature) of the 
water running into the rectifying vessel. 

With a rectifying vessel consisting of seven basins, each 
1.64 feet in diameter, and with a correctly conducted inflow 
of water, a product of 0.816 specific gravity is obtained by one 
operation from crude wood spirit of 0.965 specific gravity. 

This product can be used for many purposes, for instance 
in the preparation of varnishes. It is, however, not entirely 

FIG. 87. 

pure, being rendered turbid by water which is due to a content 
of the previously mentioned hydrocarbons; it further contains 
some acetone, methyl acetate, aldehyde, ammonia, methyl- 
amine, and is not lit for use in the production of aniline 

For further purification, this rectified wood-spirit is diluted 
with water until it shows a specific gravity of 0.934, and is 
then allowed to rest a few days, when the greater portion of 
the hydrocarbons lias separated as an oily layer on the top. 
The clear fluid is now again rectified with an addition of 2 to 


3 per cent, of lime whereby a distillate is obtained which does 
not become turbid with water, but in time turns yellow. 

For the preparation of wood spirit suitable for denaturing 
purposes, the crude wood spirit is diluted with water to from 
30 to 40 per cent., compounded with milk of lime 20.30 
liters to every 1000 liters of spirit and carefully and slowly 
rectified from large columnar stills for several days, whereby 
the following fractions are obtained : 

1. First runnings containing acetone, with 60 to 80 per 
cent, acetone. 2. High per cent, intermediate runnings, giv- 
ing bright mixtures with water, and containing 7 to 10 per 
cent, of acetone. 3. High per cent, intermediate running, 
not giving bright mixtures with water. 4. Allyl alcohol-like 
after runnings below 90 percent. 5. After runnings contain- 
ing oil. 

If the first of these fractions be diluted with water 100 
liters of water to 200 kilogrammes of distillate and acidu- 
lated with somewhat more sulphuric acid than required for 
fixing the bases and again distilled from an iron or copper 
still lined inside with lead, a product suitable for denaturing 
purposes is obtained. For this purpose all the fractions are 
used which are miscible with water without becoming turbid 
and are so rich in acetone that the mixture finally contains at 
least 30 per cent, of it and has a specific gravity of 90 Tralles. 

For the further treatment of fraction 2, water in the pro- 
portion of 1:2 is also added and then 1 to 3 per cent, of soda 
lye. The object of the addition of soda lye is to fix the phenol- 
like body, to saponify the esters and resinify the aldehyde. 
During rectification the fractions that possess less than 0.1 per 
cent, acetone are caught by themselves and designated " pure 

The third fraction is treated in the same manner but in 
place of soda lye, sulphuric acid is added. The fourth frac- 
tion is so far diluted with water that the dissolved oils are 
separated. The latter are removed and the residue, after add- 
ing sulphuric acid, is again rectified, products which may also 


partially serve as wood spirit for denaturing purposes being 
thus obtained. 

Preparation of Acetone. Acetone is a clear, mobile, ethereal- 
smelling liquid, boiling at 134 F., and of specific gravity 
0.797 at 59 F. It is prepared by heating calcium acetate in 
retorts which are connected with a cooling apparatus. The 
calcium acetate used for the purpose must be pure and should 
be brought into the retorts in a perfectly dry and pulverized 
state. It is then slowly heated until no more fluid runs off 
from the cooler. The residue in the retorts consists of calcium 
carbonate, and is again used for the preparation of calcium 
acetate. Since acetone boils at a very low temperature, pro- 
vision must be made for abundant cooling and it is best to 
use ice water for feeding the cooling apparatus. 

The decomposition of the calcium acetate to acetone and 
calcium carbonate proceeds according to the following equation: 

(CH 3 .COO) 2 Ca = CaCO 3 -f 2CH 3 .CO.CH 3 . 

This decomposition commences already in a slight degree 
at 302 F., but takes place completely only at 752 F., and 
hence the use of uniform and very high temperatures is indis- 
pensable for the production of acetone. The theoretical yield 
from 200 Ibs. of calcium acetate (gray acetate) amounts in 
round numbers to 66 Ibs. of acetone. Since the gray acetate 
contains besides calcium acetate other combinations, for in- 
stance, calcium butyrate and propionate, the yield may be 
materially less, and may in round numbers be given as about 
44 Ibs. of acetone (dimethylketone). The homologues men- 
tioned are of course also decomposed in a manner similar to 
the calcium acetate, but higher ketones are then formed which 
in the purification of the crude acetone, yield the so-called 
acetone oils. 

The decomposition of the calcium acetate is as a rule effected 
in a cast-iron pan, Fig. 88, furnished with a powerful stirrer 
and a man-hole for charging the calcium acetate. The tem- 
perature for decomposition should not exceed 752 F., and is 



controlled by a pyrometer. The vapors evolved pass first 
through a dust-separator and then through a pipe into a con- 
denser, where they liquefy. 

The crude distillate is rectified. This first distillate is 
diluted to one-half with J volume of water and again recti- 
fied, whereby a product with 90 per cent, acetone is obtained. 
The last distillation is effected with the addition of potassium 
permanganate. The first two or three liters of distillate are 


caught by themselves, and then all that boils between 122 
and 136.4 F. 

Fig. 89 shows the arrangement of a plant for the production 
of acetone. It contains several decomposing apparatuses for 
the production of crude acetone. The pipes conducting the 
vapors enter first a common collecting pipe, and from there 
are conducted to the condenser which terminates in the col- 
lecting vessel F, the quantity of fluid in it being indicated by 



the float H. The decomposing apparatuses are separated by a 
wall from the condenser and rectifier ; the fireplaces are out- 
side the working room. The decomposing apparatus is 
equipped with a dust collector T, above which is a broad 
T-pipe for conducting the vapors. This pipe also serves for 
the purpose of cleaning the dust collector. 

From the collecting vessel the crude acetone is pumped into 
the rectifier M, the latter being similar in arrangement to an 

FIG. 89. 

apparatus for rectifying alcohol. The pure acetone is caught 
by itself in the vessel G. 

The use of acetate of barium, strontium or magnesium in 
place of calcium acetate is more advantageous. The draw- 
back with the use of calcium acetate consists in that man) 
tarry substances pass over and clog the pipes, and, besides, the 
distillate is contaminated with empyreumatic substances. 

The preparation of pure acetone is not very easy, notwith- 
standing its apparent simplicity, and requires the use of per- 
fectly separating columnar stills and experience, for the rea- 
son that the admixtures of the acetone have nearly the same 
boiling points. The acetone vapors are inflammable and when 
mixed with air explosive. 


According to F. H. Meyer's system, German patent 134,978, 
pure acetone is manufactured by spreading the gray acetate 
in layers 2 to 4 centimeters deep upon sheets or sieves, which 
rest upon trucks and are pushed into the distilling muffles. 
These muffles are capable of working up 4400 Ibs. of calcium 
acetate in 24 hours. They are heated by a direct fire, a uni- 
form distribution of the heat and the same heating at all points 
of the charge being secured by proper regulation of the fire. 
When the acetone has been distilled off and the last remnants 
blown out with steam, the truck is removed from the muffle 
and is replaced by another previously charged with calcium 

The acetone oils which, as previously mentioned, are ob- 
tained in the purification of crude acetone are decomposed to 
two groups, namely to white acetone oil which comprises the 
fractions boiling at from 167 to 466 F.. and to yellow ace- 
tone oil boiling between 466' and 502 F. These oils are 
used in the celluloid industry and as additions to wood alco- 
hol intended for denaturing purposes. 

Working the wood tar. Wood tar contains a large quantity 
of combinations of which, however, only the mixture found 
in commerce under the name of creosote can be separated to 
advantage. By itself wood tar may be utilized as a preserva- 
tive coating for wood, as well as for obtaining soot, and event- 
ually as fuel in the destructive distillation of wood. 

While beech tar, for instance, contains without doubt con- 
siderable paraffin, it cannot be produced on a large scale at a 
price to compete with that of the product obtained from crude 
petroleum. The tar obtained from resinous woods contains 
oil of turpentine and can be worked to greater advantage than 
that from hard wood. 

Preparation of creosote and tar oils. The wood tar is subjected 
to distillation, this being best effected in a horizontal still of 
the shape of a steam boiler and so bricked-in as to be slightly 
inclined towards one side. On the lowest part of the still is a 
larger aperture which can be closed by a cover and clamp. 


The object of this arrangement is to facilitate the quick removal 
of the pitch-like or asphalt-like mass which remains behind in 
the still after the volatile products have been distilled off, and 
which, if allowed to become cold, adheres so firmly to the 
sides of the still that it can be detached only with great diffi- 

All the tarry substances, which separate in distilling wood- 
spirit from wood vinegar, and in neutralizing with lime or 
soda, are combined with the tar taken from the condensing 
vessels, and the mass thus obtained is subjected to distillation. 
The latter might be conducted so that the distillates resulting 
at certain temperatures are caught by themselves and the 
distillate fractionated ; but, as a rule, the distillates are only 
separated in such a manner that only the light oleaginous 
products up to specific gravity 0.980 are caught by themselves 
and worked further, separately from the heavy oils of upward 
of 1.010 specific gravity. 

At the commencement of distillation crude wood-spirit first 
passes over, which is followed by quite a quantity of acetic acid 
(distilled wood-vinegar). Next the light, and later on the 
heavy, oils pass over, a pitch-like residue remaining in the still. 
By mixing this residue, while still in a liquid state, with dry 
hot sand, blocks may be shaped from the mass thus obtained, 
which may be used for paving, like asphalt blocks. Mixed 
with culm it yields a dough-like mass which may be utilized 
for the manufacture of briquettes. If the residue cannot be 
utilized in any other manner, it may be allowed to run upon 
iron plates, and when cold, is broken up into small pieces and 
used as fuel together with coal. 

The quantities of the separate products of distillation depend 
on the nature of the wood from which the tar has been ob- 
tained and on the manner in which destructive distillation has 
been conducted. Hard woods give on an average a tar which 
by distillation yields, according to Vincent : 


Watery distillate (wood spirit, acetic acid) . . . 10 to 20 per cent. 
Oleaginous light distillate, sp. gr. 0.966 to 0.977 . 10 to 15 " 
" heavy " " 1.014 to 1.021 . 15 " 

Pitch 50 to 62 " 

The distillates, according to their specific gravities, are caught 
separately in vats, a sample, for instance, 1 quart of the fresh 
distillate, being immediately taken for the purpose of accurately 
determining the quantity of soda required for neutralizing the 
total quantity of fluid. The quantity of concentrated soda 
solution necessary for neutralization is then added to the dis- 
tillate, the whole thoroughly mixed, and the fluid allowed to 
repose until two sharply separated layers are formed, the upper 
one of which is of an oleaginous nature. The watery fluid is 
then allowed to run off and is brought into one of the vats in 
which crude wood-vinegar is caught. The oleaginous layer is 
worked further by distillation. 

The oils remaining after neutralizing the light and heavy 
distillates are combined and subjected to careful rectification. 
The receiver is changed as soon as it is ascertained by the 
thermometer that the temperature has risen above 302 F., 
and is again changed when the temperature rises above 482 
F. The hydrocarbons distilling over at below 302 and above 
482 F. might be used as solvents and for illuminating pur- 
poses, but their preparation is not remunerative. 

The distillate which has passed over between 302 F. and 
482 F. contains phenol, cresol and phlorol, which together 
form wood-creosote. The distillate is intimately mixed with 
the assistance of a stirring apparatus with highly concentrated 
soda lye (36 Be.), and the watery fluid is drawn off from the 
supernatant layer of oil, which is combined with, the other 
hydrocarbons. The watery fluid is for some time boiled in an 
open pan to expel any hydrocarbons still present, and is then 
saturated with sulphuric acid and allowed to repose. The 
fluid of a penetrating odor separated thereby is creosote, which 
is used for medicinal purposes. As a disinfecting agent it has, 
however, been superseded by the cheaper coal-tar creosote 
(carbolic acid). 


To obtain the creosote prepared according to this process 
permanently colorless, it is mixed with J to J per cent, of 
potassium dichromate and to 1 per cent, of sulphuric acid, 
allowed to repose for 24 hours and again distilled. The small 
yield of creosote and its limited use make its profitable manu- 
facture rather doubtful, except where sulphuric acid and soda 
can be procured at cheap rates. 

The heavy oils are worked up in the same manner. The 
solution formed after treatment with soda solution is not added 
to the crude wood-vinegar, but treated by itself, as it contains 
scarcely any sodium acetate, but the sodium salts of the fatty 
acids with higher boiling points, such as propionic, butyric, 
valeric and caproic acids. This lye is used either for the 
preparation of these acids, or the solution is evaporated to 
dryness and ignited with the admittance of air to regain the 

If the acids are to be prepared, the solution is evaporated 
to the consistency of syrup, slightly oversaturated with sul- 
phuric acid, and the resulting fluid diluted with water. The 
oleaginous layer collecting upon the surface consists of a mix- 
ture of the above-mentioned acids which are soluble with diffi- 
culty in water. By rectifying the mixture at the temperatures 
corresponding to the boiling points of the various acids, the 
latter are obtained in an almost pure state. 

It is still more suitable to distil the mass previously evapo- 
rated to the consistency of syrup with alcohol and sulphuric 
acid, whereby the odoriferous ethers of the various acids are 
formed, which can then be separated by fractional distillation. 

Since the heavy tar oils are entirely free from acid, and do 
not gurn in the air, they may be used as lubricants for ma- 
chinery, and were formerly much sought after for that pur- 
pose ; but at present they have been largely superseded by 
petroleum products, and in consequence of this are of less 

In the northern parts of Sweden and Finland considerable 
quantities of birch-tar oil are prepared, and below are given 



the results of a series of experiments regarding the products 
which were obtained in the distillation of a sample of Finland 
birch-tar oil. 

No. of the distillate. Limits of boiling points. Specific gravity. 

1 212 to 226 F. 0.887 

2. . . .... 4,... . - . . 356 to 437 F. 1.020 

3 . . , 588 to 644 F. 

No. 1 formed a red-yellow, very mobile oil of a not dis- 
agreeable odor of birch tar. No. 2 was of a darker color and 
of a less agreeable odor, while No. 3 represented a dark brown, 
very viscous mass. By heating the residue in the still to 
above 644 F., it is suddenly decomposed, heavy vapors being 
evolved and a lustrous, very porous coal remaining behind. 

By distilling the tar oil with caustic soda quite a series of 
oleaginous distillates are obtained.: 

No. of the distillate. Limits of boiling points. Specific gravity. 

1 212 to 284 F. 1.046 

2 ;..-.-. . . . 284 to 392 F. 1.114 

3 i. . ........ . 392to437F. 1.171 

4 -'. ' , ' , . 437 to 482 F. 1.058 

5 ':..:'. . . ., . . 482 to 734 F. 1.039 

Nos. 1 to 3 were pale, red-yellow oils ; Nos. 4 and 5 darker 
and more viscous. The residue remaining in the still at above 
734 F. was a dark black mass, soft and flexible at the or- 
dinary temperature, and becoming hard only at a lower tem- 





THE term wine in general is applied to alcoholic fluids 
which are formed by the fermentation of fruit juices, and 
serve as beverages. According to this definition, there may 
actually be as many kinds of wine as there are fruits whose 
juices, in consequence of their content of sugar, are capable 
of vinous fermentation ; and, in fact, besides the apple and 
pear, there are many other fruits which are likewise applicable 
to wine-making. Among these may be named, currants, 
gooseberries, mulberries, elderberries, cherries, oranges, dates, 
pine-apples, raspberries, strawberries, etc. But, in order to 
make the product from such fruits resemble the standard wine 
made from grapes, various ingredients have to be added, as, 
for instance, an acid, spices, coloring, and an astringent, to 
replace the extractive matter. Tartaric acid is, as a rule, 
used as an acid addition, and elderberry or whortleberry juice 
as coloring matter. The "water employed in the manufacture 
should be pure and soft. 

Ripening of fruits, In order to form a clear idea of the 
process which takes place during the growth, ripening, and 
final decomposition of a fruit, it is necessary to refer to the 
constituents which are found in an unripe fruit at its first 



Besides water, the quantity of which varies between 90 and 
45 per cent., fruits contain partly soluble and partly insoluble 
substances. The juice obtained by pressure contains the sol- 
uble constituents, such as sugar, gum, tannin, acids, salts, etc., 
while the remaining insoluble portion consists chiefly of cellu- 
lose, starch, a gum-like body, a few inorganic substances, and 
further, the characteristic constituent of unripe fruits, to which 
the term pectose has been applied. It forms the initial point 
for the phenomena observed during the growth and ripen- 
ing of fruits, and, therefore, requires a somewhat closer ex- 

In regard to its behavior, pectose approaches cellulose and 
starch. It is chiefly found in the pulp of unripe fruits, but 
also in certain roots, especially in carrots, beets, and others. 
It is insoluble in water, spirits of wine, and ether, but during 
the ripening of the fruit it undergoes a change, induced by the 
acids and heat, and is converted into pectine, which is readily 
soluble in water. To pectose are due the hardness of unripe 
fruits and also the property of many fruits and roots of boil- 
ing hard in water containing lime, the pectose combining with 
the lime. 

The formation of pectine commences as soon as the fruits 
are exposed to the action of heat, and then depends on the in- 
fluence of the vegetable acid present upon the pectose. This 
can be shown by expressing the pulp of an unripe apple. The 
juice thus obtained contains scarcely a trace of pectine, but, 
by boiling it for a few minutes with the pulp of the fruit, the 
fluid, in consequence of the formation of pectine, acquires a 
viscous quality, like the juice obtained from ripe fruits. 

Pectine, nearly pure, is white, soluble in water, non-crystal- 
lizable, and without effect upon vegetable colors. From its 
dilute solution it is by alcohol separated as a jelly, and from 
its more concentrated solution, in long threads. Brought into 
contact with alkalies or alkaline earths, pectine is transformed 
into pectic acid. Under the influence of a peculiar ferment 
called pectase, which will be described later on, pectine is 


transformed into pectosic acid, and by dilute acids into meta- 
pectic acid. 

By boiling a solution of pectine in water for a few hours, it 
partially loses its viscous condition and separates a substance 
called parapectine, which shows the same behavior as pectine, 
except that it is not precipitated by neutral lead acetate. 
When treated with dilute acids the parapectine is transformed 
into metapectine, which might be called metapectous acid, as 
it shows a decidedly acid reaction and colors litmus paper 
strongly red. 

Metapectine is soluble in water, non-crystallizable, and, like 
pectine and parapectine, insoluble in alcohol, which precipi- 
tates it from its solutions in the form of a jelly. On being 
brought into contact with bases it is also transformed into 
pectic acid. It differs from pectine and parapectine in that 
the solution is precipitated by barium chloride. 

Pectase, the peculiar ferment previously referred to, is sim- 
ilar in its mode of action to diastase and emulsion. It can be 
obtained by precipitating the juice of young carrots with alco- 
hol, whereby the pectose, which was at first soluble in water, 
becomes insoluble, without, however, losing its effect upon the 
pectous substances. 

By adding pectase to a solution of pectine, the latter is im- 
mediately converted into a jelly-like body, insoluble in water. 
This phenomenon is the pectous fermentation, which may be 
compared with lactic acid fermentation. It is not accom- 
panied by an evolution of gas, and may take place with the 
air excluded, a temperature of 86 F. being most favorable for 
its progress. 

Pectase is an amorphous substance. By allowing it to stand 
in contact with water tor a few days, it decomposes, becomes 
covered with mold-formations, and loses its action as a fer- 
ment, this action being also destroyed by continued boiling. 
In the vegetable organism it occurs in a soluble as well as in- 
soluble state. 

Roots such as carrots, beets, etc., contain soluble pectase 


and their juice added to a fluid containing pectine in solution 
immediately induces pectous fermentation, while the juice of 
apples and other acid fruits produces no effect upon pectine, 
the latter being present in them in a modified insoluble form 
and accompanying the insoluble portion of the pulp. On 
adding the pulp of unripe apples to a pectine solution it gel- 
atinizes in a short time, in consequence of the formation of 
pectosic and pectic acids. It is therefore due to the presence 
of these acids that many ripe fruits are so easily converted 
into jellies. 

Pectosic acid is the result of the first effect of the pectase 
upon pectine ; it being, however, also formed by bringing 
dilute solutions of potash, soda, ammonia or alkaline carbon- 
ates in contact with pectine. In all these cases salts are formed 
which, when treated with acids, yield pectosic acid. The lat- 
ter is gelatinous, and with difficulty dissolves in water. In 
the presence of acids it is entirely insoluble. It is quickly 
transformed into pectic acid by long boiling in water, by pec- 
tase, or by an excess of alcohol. 

By allowing pectase to act for some time upon pectine, pec- 
tic acid is formed ; the same conversion taking place almost 
instantaneously by dilute solution of potash, soda, ammonia, 
alkaline carbonates, as well as by barium, lime and strontium 
water. Its formation in the above-described manner is pre- 
ceded by that of pectosic acid, which, as previously men- 
tioned, is converted by the same agents into pectic acid. 

Pectic acid is insoluble in cold, and scarcely soluble in hot, 
water. By boiling it, however, for a certain time in water, and 
constantly replacing the water lost by evaporation, it disappears 
entirely, and is converted into a new acid, soluble in water. 
Alkalies decompose it very rapidly, the final result being met- 
apectic acid, which is soluble in water, but non-crystallizable. 
On boiling in hot water, the solution forms, after cooling, a 

Pectic acid further possesses the special property of dissolv- 
ing in a large number of alkaline salts and forming with them 


true double salts, which always show a decidedly acid reaction, 
dissolve in water, and on cooling form consistent jellies. 

By boiling for a few hours a solution of a pectous salt, the 
latter is transformed into a parapectous salt which, when de- 
composed by a dilute acid, yields parapectic acid. It is non- 
crystallizable, shows a strong acid reaction, and forms with 
alkalies soluble salts. It is precipitated by barium water in 

Metapectic acid is formed in various ways, among others 
by leaving an aqueous solution of parapectic acid to itself for 
some time, but also by the action of the lime contained in the 
cell-tissues of roots and fruits upon pectose. It is insoluble in 
water, does not crystallize, and gives soluble salts with all 
bases. With an excess of bases the salts acquire a yellow 
coloration. They are precipitated by basic lead acetate. 

What has been said in the preceding may be briefly con- 
densed as follows : 

1. By the influence of heat upon pectose pectine is formed. 

2. Pectine is transformed into parapectine by boiling its 
aqueous solution for several hours. 

3. Parapectine, when treated at a boiling heat with dilute 
acids, is converted into metapectine. 

4. Pectase converts pectine into pectic acid. 

5. By long-continued action of pectase upon pectine, pectic 
acid is formed. 

6. Pectic acid is by boiling water transformed into para- 
pectic acid. 

7. An aqueous solution of parapectic acid is rapidly con- 
verted into metapectic acid. 

All these bodies are derived from pectose, which through all 
these transformations has not even suffered a change in the 
proportion of weight of its constituents (carbon, hydrogen, and 
oxygen); and hence all have the same qualitative and quanti- 
tative compositions. This may, perhaps, sound odd, but 
chemistry presents numerous analogies for such cases, and 
hence the term isomeric has been applied to bodies which, with 


the same quantitative composition, exhibit very different 
chemical properties. 

The changes pectose undergoes by the influence of heat, by 
the action a peculiar ferment, acid and alkalies, and the re- 
sulting combinations mentioned above, have of course been 
artificially effected by chemical means. They resemble, how- 
ever, so closely the state of fruits in the course of their growth 
and ripening, and the influences and conditions to which fruits 
are exposed in nature are sufficiently similar to those artifi- 
cially induced, that their action may be reasonably supposed to 
be the same. We know from daily experience that heat pro- 
motes the development and ripening of fruit. Fruits contain 
pectose and acids, and alkalies and bases are conducted to 
them from the soil ; and hence in fruit in a normal state of 
development none of the chemical agents are wanting which 
the chemist uses for the production of derivatives of pectose. 

If the transformation of substances under the influence of 
other substances be considered as dependent on chemical 
processes, the development of a fruit from its first formation 
to complete ripeness, and even to its decomposition, rotting, 
and putrefaction, is a chemical process in the widest sense of 
the word. This is evident, not only from what has been said 
in the preceding, but has also been plainly shown by special 
chemical researches into the changes fruits undergo during 
their development and perfection. The results of these 
researches are briefly as follows : 

1. The quantity of water contained in the pulp of a fruit 
is considerable ; it varying between 45 and 90 per cent. In 
many fruits the content of water remains unchanged during 
the different periods of ripening, but, as a rule, it is somewhat 
greater in the commencement. 

2. Fruits of the same kind examined at the same season of 
the year always contain the same quantity of water ; the same 
holding good as regards the various parts of the pulp of a fruit. 

3. The solid constituents in the pulp of fruits amount to 
between 10 and 25 per cent. They consist of soluble substances 


which dissolved in the water from the juice of the fruits ; and 
of insoluble bodies which compose the membranes of the cells. 

4. The quantity of soluble substances always increases with 
increasing ripeness, while the weight of the insoluble decreases ; 
and hence it may be said that the soluble substances contained 
in the juice of a fruit are formed at the expense of the insolu- 
ble portion of the pulp. The bodies which become soluble 
are starch, pectose, and a gum-like substance capable of being 
converted into gum. 

On this modification of the solid portion of the pulp of a 
fruit depend also the changes a fruit undergoes in regard to 
hardness and transparency during ripening. 

According to the mode of action of the pectase and acids 
upon the pectose, all ripe fruits contain pectine. 

5. Various acid fruits, such as plums, cherries, etc., are fre- 
quently observed to secrete a neutral juice which, in conse- 
quence of the evaporation of the water, leaves a gum-like 
substance upon the exterior of the fruit. This phenomenon 
throws some light upon the separation of gum as it appears in 
many trees, and which, when it occurs very abundantly, is 
actually a disease. 

In fruits becoming thus covered with a gum, a transparent, 
neutral substance insoluble in water occurs stored in the cells 
of the pulp. Under the influence of nitrogenous substances, 
which act as a ferment, and perhaps also of acids, this gum-like 
substance is modified and transformed into actual gum, which 
is then converted into sugar in the interior of the pulp of the 
fruit ; an excess of this gum-like substance being secreted and 
forming a firm coating upon the exterior of the fruit. 

6. The sugar occurring in ripe fruits is evidently derived 
from various sources. The occurrence of a large quantity of 
starch in many unripe fruits, especially in apples, and its com- 
plete disappearance at the time of ripeness, allow of no other 
explanation than that the sugar occurring in fruits is formed 
by the conversion of the starch under the influence of the acids 
present ; other indifferent substances, such as gum, vegetable 


mucus, etc., undergoing similar transformations and yielding 
in this manner a certain portion of sugar. Even tannin, which 
occurs in all unripe, but not in ripe, fruits, can be changed by 
acids and ferments so as to form sugar. 

Thus far nothing justifies the supposition that the acids in 
fruits, such as tartaric, citric, malic acids, are converted into 
fruit sugar. To entertain such an opinion it would have to 
be supposed that the molecules of these acids, which are far 
more simple than those of fruit-sugar, become more complex 
and are converted into sugar. In such natural transforma- 
tions the reverse is, however, generally the case, the molecules 
always endeavoring to become the more simple the farther they 
withdraw from organized structures. 

7. It has been attempted to explain in various ways the very 
remarkable phenomenon of the gradual disappearance of the 
acid in ripening fruits. It might not be impossible that the 
acid of a fruit, is neutralized by the bases conducted to it 
through the juice ; or that it is covered by the sugar or the 
mucous substances formed in the juice ; or, finally, that it dis- 
appears at the moment of ripeness by suffering actual combus- 
tion. An examination of these various theories leads to the 
conclusion that the acid is neither neutralized nor covered by 
the sugar or the mucous substances, but that it actually under- 
goes slow combustion. 

During the stages of development and ripening, a fruit 
passes through two different stages sharply separated from 
each other by definite chemical phenomena. In the first 
stage, which may be designated as that of growth, whilst the 
fruit remains green, its relation to the atmosphere appears the 
same as that of leaves, for it absorbs carbonic acid and evolves 
oxygen. During this epoch it increases rapidly in size, and 
receives through the stem the inorganic substances, indispens- 
able for its development, and the water. If, at this stage, it 
is taken from the tree, it soon commences to wither and decay. 
But in the second period, when it fairly begins to ripen, its 
green color is, as a rule, replaced by a yellow, brown-red, or 


red. Oxygen is now absorbed from the air and carbonic acid 
is evolved, whilst the starch and cellulose are converted into 
sugar under the influence of the vegetable acids, and the fruit 
becomes sweet. When the sugar has reached the maximum 
the ripening is completed, and if the fruit be kept longer, the 
oxidation takes the form of ordinary decay. 



FOR the preparation of fruit-wines, not only the fruits culti- 
vated in our gardens and orchards on account of their fine 
flavor are used, but sometimes also others which do not by any 
means possess an agreeable taste, and whose juices, after fer- 
mentation, yield a product which has at least only a very 
doubtful claim to the name of " wine." The utilization of such 
material for wine-making can only be explained by special 
fancy, and hence here only such fruits will be considered 
as, on account of the nature of their juices, will yield with 
rational treatment a beverage of a sufficiently agreeable taste 
to be liked. 

For making fruit-wine, sugar not only by itself but also 
in its proportion to the free acid present, is undoubtedly the 
most important constituent of the fruit. The following table 
from Fresenius gives the average percentage of sugar in 
different varieties of fruit : 


Peaches 1.57 p. c. 

Apricots. . .' 1.80 

Plums 2.12 

Keine Claudes 3.12 

Greengages ...... 3.58 

Raspberries 4.00 

Blackberries 4.44 

Strawberries .5.73 

Whortleberries. . .5.78 

Currants 6. 10 p. c. 

German prunes 6.25 " 

Gooseberries 7.15 " 

Pears 7.45 " 

Apples 8.37 " 

Sour cherries ...... 8.77 " 

Mulberries 9.19 " 

Sweet cherries 10.79 '* 

Grapes 14.93 " 



II. Table according to average percentage of free acid 
expressed in malic acid : 

Pears 0.07 p. c. 

Greengages 0.58 u 

Sweet cherries 0.62 " 

Peaches 0.67 " 

Grapes 0.74 " 

Apples 0.75 " 

German prunes 0.89 " 

Keine Claudes 0.91 " 

Apricots 1.09 " 

Blackberries 1.19 p. c. 

Sour cherries 1.28 " 

Plums 1.30 " 

Whortleberries 1.34 " 

Strawberries 1.37 " 

Gooseberries 1.45 " 

Kaspberries ....... 1.48 " 

Mulberries 1.86 " 

Currants. . 2.04 " 

III. Table according to the proportion between acid, sugar, 
pectine, gum, etc. 


Apricots .... 
Peaches .... 
Easpberries . . 
Currants. . . . 
Keine Claudes . 
Blackberries . . 
Whortleberries . 
Strawberries . . 
Gooseberries . . 
Mulberries . . . 
Greengages . . 
Sour cherries . . 
German prunes . 
Sweet cherries . 
Grapes .... 
Pears . 



Pectine, gum, etc. 















IV. Table according to the proportion between water, solu- 
ble and insoluble substances. 



Composition of the juice in 
100 parts, without the in- 
soluble substances; 



substances. Water. 


Raspberries .... 






Blackberries .... 






Strawberries .... 






Currants . . . . 

Whortleberries. . . 






Gooseberries .... 






Greengages .... 














German prunes. . . 






Sour cherries . . . 






Mulberries .... 












Reine Claudes . . 






Sweet cherries . . . 
Graoes . . . 









V. Composition 
sugar, pectine, etc. 

of the juice according 
in 100 parts : 

to the content of 


Sugar, etc., 
p. c. p. c. 
. 1.99 10.05 
2 04 6 98 

German prunes .... 

Sugar, etc., 
p. c. p. c. 
7.56 4.70 
8.00 1.24 
8.12 0.77 
8.43 4.02 
9.14 4.59 
10.00 2.22 
10.44 2.17 
15.30 2.43 
16.15 2.07 

. . 1.42 n. r 

Apricots . 

. 2.13 8.19 
2.80 5.40 
. 4.18 6.45 
. 4.84 1.73 
. 5.32 1.72 
. 6.89 0.13 
. 7.30 0.16 

free acid in 1 

. . . 0.09 p. c. 
. . . 0.59 " 
. . . 0.67 " 
. . . 0.80 u 
. 82 " 

Whortleberries . . . . 



VI. Content of 

Reine Claudes .... 

Sour cherries . . . 

Sweet cherries. .... 

.00 parts of juice : 

Blackberries . ... 

Sour cherries . . 

52 " 

57 " 

Gooseberries .... 

1.63 u 


.72 " 


85 u 

80 tk 

Sweet cherries .... 
German prunes. . . . 

. . 0.88 " 
. . . 1.08 " 
. 1.29 " 

.88 " 
2.02 " 
2.43 " 



Tables V. and VI. represent the proportion in which the 
soluble constituents of the fruit are found in the juice or must 
obtained from them. In the practical execution of the pre- 
paration of fruit wines we will have occasion to refer to these 

For the preparation of wine, only the soluble substances, 
which pass into the must, and from which the wine is formed, 
are chiefly of interest, and it will be necessary to consider 
them somewhat more closely. 

Grape-sugar or Glucose. This sugar is widely diffused 
throughout the vegetable kingdom, it occurring in most kinds 
of sweet fruits, -in honey, etc. Artificially it can be readily 
obtained by heating a solution of cane-sugar with a dilute acid. 
It is also formed by dissolving cane-sugar in wine. On a large 
scale it is prepared by boiling starch with very dilute sulphuric 
acid for several hours, neutralizing the liquid with chalk and 
evaporating the solution. 

Grape-sugar is much less sweet than cane-sugar. In alco- 
hol of 90 per Tr. it is sparingly soluble ; in hot water it dissolves 
in every proportion ; of cold water it requires, however, about 
1J- parts for solution. It crystallizes from aqueous solution 
with one molecule of water, in cauliflower-like masses and from 
hot alcohol in warty, anhydrous needles. A solution of crys- 
tallized grape sugar turns the plane of polarization to the 
right, but one of anhydrous grape-sugar to the left. 

Acids. The acid reaction of fruit juices is partly due to 
malic acid and partly to citric acid, and also as in the case of 
grapes to tartaric acid. As a rule all these acids are present ; 
in currants citric acid predominates; in apples, etc., malic 

The presence of potassium in grape-must gives rise to the 
formation of potassium bitartrate of crude tartar. Tartar 
requires for its solution 240 parts of cold water ; in alcoholic 
fluids it is less soluble, and hence it is found as a crystalline 
deposit in wine casks. Fruit-musts contain no tartaric acid, 
and, consequently, the wines prepared from them cannot de- 


posit tartar. The salts formed by malic and citric acids with 
potassium being readily soluble and even deliquescent form 
no deposit in the wine. 

Albuminous substances. By this general term are designated 
several nitrogenous vegetable substances which have the same 
composition ; they being vegetable albumen, fibrin, and glue. 
The quantities of these substances in the different musts are, 
on the one hand, so small, and the difficulty of accurately dis- 
tinguishing them from each other is, on the other, so great, 
that it is scarcely possible to definitely determine the kind 
actually present in the fruit juice. Most likely all are present 
at the same time. 

For the preparation of wine these bodies are of importance ; 
they furnishing the material for the development of the yeast- 
fungus during fermentation. 

Pectous substances. Under the heading " Ripening of fruits," 
the pectous substances have been sufficiently discussed. They 
are scarcely ever wanting in a fruit juice, but being insoluble 
in alcoholic fluids they are entirely separated with the yeast, 
and hence are not present in fruit-wines. 
'' Gum and Vegetable Mucilage. Our knowledge as regards 
gum is still limited. Gum-arabic, which may be studied as a 
representative of this class, is an exudation from certain species 
of acacia and consists essentially of arabin. It is generally 
supposed to be soluble in water, but on endeavoring to filter a 
somewhat concentrated solution not a drop will be found to 
run off, and the little which possibly may pass through the 
filter is by no means clear. 

Closely related to gum-arabic is bassorine, the gum which 
exudes from the cherry, plum, almond, and apricot trees. It 
does not give a slime with water, but merely swells up to a 
gelatinous mass. 

Wine brought in contact with the smallest quantity of gum- 
arabic remains permanently turbid and cannot be clarified by 
filtering or long standing. From this behavior of gum it may 
be concluded that, though it may occur dissolved in the must, 
it is not present in the wine. 


The various kinds of vegetable mucilage have also not yet 
been accurately examined ; it only being known that there are 
quite a number of them. It is, however, likely that only a 
few of them are actually soluble in water. Though the muci- 
lage of certain seeds, such as linseed and quince-seed, may be 
considered to be as soluble in water as gum-arabic, and per- 
haps more so, because it is a perfectly clear fluid drawing 
threads, yet on filtering it will be found that what passes 
through contains scarcely a trace of mucilaginous substance. 
Hence, it is doubtful whether mucilages exist which are 
actually soluble in water, and whether they occur in wine. 
Artificial dextrin is, however, an exception, as it forms with 
water a perfectly clear fluid, which can be filtered. Attention 
may here be called to an easy method of distinguishing be- 
tween solution of gum-arabic and of dextrin. The first can- 
not be heated, even for a minute, over an open fire without 
scorching, while the latter can be completely boiled down 
without fear of burning. 

Tannin. Several kinds of tannin occur in plants, which can, 
however, be finally reduced to two modifications, viz.: patho- 
logical and physiological tannin. The first occurs in large 
quantity in nut-galls, especially in the Chinese variety, also in 
sumach (the twigs of Rhus coriaria) and in many other plants. 
Pathological tannin is characterized by splitting under the 
influence of dilute acids as well as by fermentation into gallic 
acid and grape-sugar. Furthermore, it completely precipitates 
glue from its solutions, but it is not suitable for the conversion 
of the animal skin into technically serviceable leather which 
will withstand putrefaction. Besides, only the gallic acid 
obtained from pathological tannin yields pyrogallic acid by 
destructive distillation. 

Physiological tannin is chiefly found in materials used for 
tanning. It cannot be split by dilute acids or fermentation, 
does not yield gallic acid, and the product of destructive dis- 
tillation is not pyrogallic acid, but pyrocatechin or oxyphenic 
acid. It converts the animal skin into perfect leather. 


There can be but little doubt that physiological tannin is 
the variety found in fruits and fruit-juices. Generally speak- 
ing, a content of tannin in wine is not exactly a- desirable 
feature, as it is readily decomposed. It can only have an ad- 
vantageous effect when the wine contains an excess of albumin" 
ous substances which the tannin removes by entering 
into insoluble combinations with them. This may be the 
reason why wine containing tannin is considered more dura- 
ble, because if it contained albuminous substances in large 
quantity it would be still more readily subjected to changes. 
Under such circumstances a small addition of tannin to the 
wine may be of advantage, though instead of tannin it is 
advisable to use an alcoholic extract of grape-stones, they being 
uncommonly rich in tannin. 

Inorganic constituents. The inorganic constituents of the 
different varieties of fruit are very likely the same, namely, 
potash, lime, magnesia, and sulphuric and phosphoric acids, 
they varying only in the proportions towards one another and 
in the total quantity of all the substances. Moreover, their 
quantity is too small to exert an influence upon the quality of 
the wine to be produced, being of interest only in regard to 
the exhaustion of the soil. Though lime and sulphuric acid in 
sufficient quantity occur almost everywhere in the soil, this 
cannot be said of potash and phosphoric acid. Unfortunately 
there are no accurate statements regarding the amount of these 
substances which is withdrawn from the soil by the crop of one 
year, but there can be no doubt that it is very large, and that 
consequently fruit trees from time to time require a certain 
amount of manure in order to return to the soil what has been 
taken from it. 

Fermentation. Fermentation is a chemical process which is 
always caused by the presence of a ferment or a substance in a 
peculiar state of decomposition. Although to induce fermen- 
tation the presence of a ferment is necessary, it does not take 
part in the decomposition of the fermenting substance. The 
products of fermentation vary according to the nature of the 


fermenting body, as well as according to the nature of the fer- 
ment itself. Each peculiar kind of fermentation requires a 
certain temperature, and it is nearly always accompanied by 
the development of certain living bodies (bacteria or fungi). 

.When yeast is added to a dilute solution of dextrose or 
another glucose, vinous fermentation speedily sets in ; whilst a 
solution of cane-sugar undergoes fermentation but slowly, the 
cause being that this sugar must first be converted into inverted 
sugar before fermentation can commence. Vinous fermenta- 
tion proceeds most rapidly at 77 to 86 F., and does not take 
place below 32 or above 95 F. The presence of a large 
quantity of acids or alkalies prevents fermentation, while if the 
liquid has a faint acid reaction, fermentation proceeds best. 

The yeast which is formed in the fermentation of the juice 
of grape and other kinds of fruit is produced from soluble albu- 
minous bodies contained in fruit. It consists of one of the 
lowest members of the vegetable kingdom (Torula cerewsise)^ 
and under the microscope is seen to be made up of little oval 
transparent globules, having a diameter of not more than 0.1 
millimeter and often adhering in clusters and strings. They 
are propagated by budding, and die as soon as they have 
reached their highest state of development. In contact with 
air and water yeast soon undergoes putrefaction. 

The chief products of vinous fermentation are alcohol and 
carbon dioxide ; a small quantity of the sugar being at the 
same time converted into other products, about 2.5 per cent, 
being transformed into glycerin and 0.6 to 0.7 per cent, into 
succinic acid. A further portion of the sugar, about one per 
cent., is assimilated in the form of cellulose by the yeast and 
separated. By the simultaneous formation of these different 
secondary products about 5.5 to 6.5 per cent, of sugar is lost 
in the formation of alcohol. As they are not always formed 
in equally large quantities, no conclusion can be arrived at 
from the content of sugar in the must as to the quantity of 
alcohol corresponding to theory in the finished wine. It is, 
as a rule, supposed that the sugar yields one-half its weight 


of alcohol, which is sufficiently correct for all practical pur- 

Absolute alcohol, i. e., alcohol entirely free from water, is a 
very mobile fluid, clear as water and almost odorless. It boils 
at 173 F., and when it is cooled down to 148 F. it becomes 
viscid, but does not solidify. Its specific gravity at 32 F. is 
0.80625, and at 59 F. 0.79367. It is very inflammable, and 
burns with a blue, non-luminous flame. It absorbs moisture 
with great avidity, and is miscible with water in all propor- 
tions, the mixture evolving heat and undergoing contraction. 

The methods for determining the content of alcohol in a 
fluid have already been previously given. 

Sucdnic add. No accurate researches have as yet been 
made in regard to the quantity of this acid in wine, its influ- 
ence upon the quality of the wine, and the conditions under 
which more or less of it is formed during fermentation. Ac- 
cording to Pasteur, the more succinic acid is formed the slower 
fermentation progresses; the weaker the development of yeast 
and the less nourishment offered to the latter. In acid fluid 
more succinic acid is formed than in neutral. 

Succinic acid is quite readily soluble in a mixture of alcohol 
and water, and consequently also in wine. Its taste is not 
very sour, but disagreeable, and adheres for some time to the 
tongue ; hence its presence can scarcely be expected to give 
an agreeable taste to the wine. 

Glycerin. Glycerin being found in grape-wines, in which 
it is formed from the sugar by fermentation, there can scarcely 
be any doubt of its formation under the same conditions in 
fruit wines. According to Pasteur, the quantity of glycerin 
in wine is in a definite proportion to the succinic acid formed, 
and, hence, more glycerin would be produced with slow fer- 
mentation and in an acid fluid. In red wines Pasteur found 
4 to 7 per cent, of glycerin. 

Pure glycerin is a colorless, very viscid liquid having a spe- 
cific gravity of 1.27. It can be mixed with water and alco- 
hol in all proportions and possesses a very sweet taste. It is 


very likely that the mild sweet taste of many ripe wines is due 
to a certain content of glycerin. 

A solution of 7 parts of glycerin in 1000 of water (the pro- 
portion in which Pasteur found glycerin in wine) does not 
possess a sweet taste and differs from water only in being more 
insipid. By adding to such a solution 100 parts of alcohol, 
the mixture shows a taste different from that of alcohol alone, 
diluted in the same proportion, the predominant taste of the 
latter being decreased by the glycerin and that of the mixture 
becoming milder. Hence a certain importance has to be as- 
cribed to the glycerin. 

Carbonic acid. The greater portion of the carbonic acid 
formed by fermentation escapes as a gaseous body during the 
process, but a certain portion remains dissolved in the wine as 
long as the temperature of the latter is not raised. The tem- 
perature of cellars generally increases, however, towards the 
end of spring, which causes anew a slight development of car- 
bonic acid in consequence of which the wine again becomes 
turbid. The presence of carbonic acid is of advantage only in 
young wine, as its protects it from the direct action of the air 
by forming a layer upon the surface. In old wines it conceals, 
however, the fine aroma and taste, making them appear 
younger than they actually are. 

Though it cannot be said that carbonic acid plays an essen- 
tial part in the preparation of wine, it deserves attention on 
account of its deleterious influence upon the workmen. To 
avoid all injurious consequences, provision should be made 
for a thorough ventilation of the cellar by means of windows 
and doors. If fermentation is carried on in barrels, the car- 
bonic acid developed in a number of them should be conducted 
by means of tubes secured air-tight in the bungs to a zinc pipe 
which passes through a suitable aperture into the open air. 

Alkaloid in wine. It has frequently been asserted that an 
alkaloid exists in young wine, which not being contained in 
the must or the yeast must have been formed from the nitro- 
genous constituents of the yeast or of the fluid during fermen- 


tation. It has not been found in old wine, and it is therefore 
concluded that it in time decomposes. Should this observation 
be confirmed, it would explain the difference in the effects of 
the very intoxicating young wines and of old wines. 



THE first step in the preparation of fruit-wines is to obtain 
the juice or must from the fruit. Stamping or grinding and 
subsequent expressing of the paste thus formed by means 
of strong pressure suffice in most cases for berries and other 
small fruits. With apples, etc., this manner of reduction is 
not only difficult, but also connected with considerable loss 
caused by larger and smaller pieces jumping from the trough. 

The earliest appliance known was simply a trough in which 
the apples were reduced to an imperfect pomace by rolling 
them with a heavy cylindrical stone or by pounding them as 
in a mortar. An improvement was the production of the 
English cider-mill. This consisted of a pair of coarsely cor- 
rugated iron cylinders from which the apples fell to a second 
pair close together and finer in their surfaces, and passed 
through finely mashed to the pomace vessel underneath. In 
1852, Mr. W. 0. Hickock, of Harrisburg, Pa., invented a 
portable cider-mill which consisted of a pair of small horizon- 
tal cylinders armed with small spirally arranged teeth or spikes 
revolving close together, one at a higher velocity than the 
other. The apples were first broken by the action of a 
coarsely-fluted roller which revolved against a table under 
the hopper, and after passing between the cylinders, the apples 
were not only bruised but also grated into the required pomace. 
This machine was capable of grinding 100 bushels of apples 
per day. Numerous modifications have been made in the 


plan of Mr. Hickock's mill, some being simply spiked cylinders 
against which the apples were carried and held till grated by 
reciprocating plungers. 

The limits of this work will not permit of a notice of all 
the various styles of portable mills before the public or the 
multitude of graters or apple grinders, many of which possess 
excellent points and are worthy of commendation. An excel- 
lent apparatus for crushing apples is the crushing-mill shown 
in Figs. 90 and 91, B C (Fig. 91) representing the cylinders 
provided with teeth. A hopper, A, receives the apples, which 
pass between the cylinders, where they are crushed and fall 

FIG 90. FIG. 91. 

into the receiver F placed underneath. Two men operate 
this mill by means of cranks. Larger and stronger mills are 
used when the quantity of apples seems to require them, and 
in that case horse-power is applied. 

Fig. 92 shows Davis's star apple-grinder. The grinder 
shown in the illustration is a heavy machine weighing 340 
Ibs. The cylinder is 12 inches in diameter and 12 inches long, 
is turned and carefully balanced, has grooves planed in to 
receive the knives, six in number, which are finely made and 
tempered. Each knife furnished is made of steel-plated iron, 
the steel being very thin and having a back of iron ; there 


is no danger of breaking, although made very hard. The 
end of the cylinder is banded with wrought-iron bands 
and the knives are set with set- screws. The shaft is of steel 
and runs in anti-friction metal. The concaves are hung at 
top, so they can swing back at the bottom to allow stone, pieces 
of iron, etc. to pass through without injuring the knives. The 
concaves are held to their places by a bolt which allows the 
concave to be set as close as desired to the cylinder, and is 
held to its place by coil-springs which will give enough to 
allow stones to pass and yet hold rigid in grinding even fro- 
zen apples. The frame is one casting, and as the concaves 

are fast to the frame they cannot get out of line or be dis- 
placed, as in the case when the concave is fast to the hopper. 
The hopper can be readily removed to adjust knives, and all 
parts are adjustable and easy to get at. This machine can be 
gauged to grind from 200 to 400 bushels per hour. Power 
required to grind six bushels per minute, about six horse-power, 
say about as many horse-power as desired to grind bushels per 

Presses. For obtaining the juice from berries, etc., a press 
is generally not required, or at least only a slight pressure ; 
the greater portion of it running out from the must by placing 



the latter upon a cloth spread over a perforated bottom in a 
vat. The juice retained by the lees, which, as a rule, is very 
sour and has to be diluted with water, can be extracted with 
the latter more completely than is possible with the strongest 

For obtaining the juice from apple pomace, etc. a good press 
is, however, an important auxiliary. Before the introduction 
of screws the method of extracting the juice of the apple was 
by the use of heavy weights, wedges, and leverage. Until 
within a late period a large wooden screw was used and is even 
now employed in some sections of the country. Of these 
screws two and frequently three and four, set in a strong frame- 
work of double timbers, were found no more than sufficient to 
separate the cider from the pomace. In order to operate these 
screws a long heavy wooden lever became necessary, which 
required the united services of four or five men to handle, and 
not unfrequently the strength of a yoke of oxen was called 
into requisition before the work 
could be accomplished. An im- 
provement upon the wooden screw 
was made by the substitution of 
the iron screw and iron nut. But 
the objectionable feature of hav- 
ing to handle heavy and cumber- 
some levers still remained, mak- 
ing labor irksome and expensive. 
In modern presses this difficulty 
has been entirely overcome, and 
the juice is extracted from the 
pomace with great ease and com- 

Of the many presses before the 
public, a hand-press a-nd a power- 
press are here illustrated ; presses of all sizes between these 
two are found in the market. Fig. 93 shows the " Farmer's 
cider-press." It is 7 feet 1 inch high, with a width between 

Fig. 93. 


the rods of 3 feet If inches. It will hold 15 to 16 bushels of 
apples at a pressing and is especially designed for individual 
use. It is also admirably adapted for squeezing the juice from 
small fruits, berries, etc. 

Fig. 94 shows the " Extra power cider-press," with revolv- 
ing platform. It is 13 feet 4 inches high, 6 feet 4 inches wide 

FIG. 94. 

between the rods, and has a platform 13 feet 3 inches long. 
It gives a pressure of 250 tons. The press is always loaded 
in one place, and consequently the grater can be located 
immediately over the middle of the cheese, avoiding the 
necessity of conveying the pomace from one end of the press 



to the other. This press can easily make a pressing of 12 
barrels of cider each hour. 

Fig. 95 shows the revolving platform belonging to the 
above press, for which the following advantages are claimed : 
1. Both ends of the platform are loaded and unloaded in the 
same place. 2. It is so geared that one man can easily and 
quickly revolve it. 3. The grinder can be directly over the 
centre of the cheese, thus avoiding all the labor of shoveling 
the pomace. 4. The pomace being dropped in the centre of 
the cheese, it is an easy matter, to spread it with equal density 
over the entire surface, thus building a cheese that is not 
liable to tilt or slide. The cider runs into a copper basin in 

the centre of the platform between the two cheeses. The basin 
is so arranged that it receives the cider while the platform is 
being revolved as well as while the press is working. 

A is the copper basin- to receive the cider from platforms, 
and has an outlet through the bottom, about 6 inches in diam- 
eter, for the cider to pass off into the tank below. B is a cop- 
per tube encasing the rods. C, (7, C, C are four posts fastened 
to the platform to hold guide-pieces for racks. D, D are rack 

Improved Racks. The single racks are made of some light 
and tough wood bass-wood or spruce seems best cut into 
strips about JXJ inch and placed about J inch apart, with 


four, five, or more elm strips, 2 inches wide about f inch thick, 
placed across and nailed to the narrow slats. The 2-inch slats 
extend beyond the narrow ones on each side about 4 inches. 
This is to support the wings, which are fastened to the rack 
by 3 or more bronze hinges. These wings, with the aid of 2 
retaining bars, make the box to form the pomace in. The slats 
are rounded on the edges, so as not to injure the press-cloth. 
Steel wire nails or wire staples are used of sufficient length to 

Double racks are made by using slats -ft- Xf inch. The slats 
on one side are laid directly across the slats on the other side. 
Four wide slats are put at the outer edges, then these are all 
fastened together by steel wire nails or staples. These racks 
have the advantage of having an even surface on each side. 
The press-cloth will last much longer than when used on single 
racks, where it is strained over 4 to 9 elm slats. 

To lay up a cheese with the improved rack, commence on 
the platform of the press and lay a rack ; then turn up the 
wings on each side of the rack and place the retaining bars on 
each end, with the hooks on the outside of the wings, so as to 
hold them up. Over this box spread the cloth, fill the box 
evenly full of pomace, then turn in the sides and ends of the 
cloth over the pomace, the cloth being of sufficient size to 
cover it. The retaining bars are then removed, allowing the 
wings to fall in place. Another rack is placed on the cheese 
just made, the retaining bars placed in position to hold up the 
wings, another cloth placed on the box, etc., and this opera- 
tion is continued until there is the right number of layers in 
the press. A rack should be placed on the top of the last layer. 
A guide should be used in laying up the cheese, so as to bring 
each rack directly above the other. 

Plain racks.- These are made, either single or double, of 
slats of the same description and dimensions as are used in the 
improved racks, but in the place of wings and retaining bars, 
a form square in size and 4 inches deep is used to form the 
sides of a box for the pomace. In laying up a cheese com- 


mence by placing a rack on the platform, and upon this place 
the form, spread a cloth over the form and fill even up with 
pomace ; then fold the ends and sides of the cloth over onto 
the pomace, as described with the other style of rack, and 
remove the form. Place another rack on the layer just formed, 
and put the form on that and proceed as before until the 
cheese is complete. It will require one cloth less than the 
number of racks used for a cheese. Care must be exercised in 
laying a cheese to have the racks come evenly, as they are 
liable to tilt if they overhang. The best way to avoid the 

FIG. 96. 

liability to slide or tilt is to lay the racks alternately the length 
and breadth of the press. 

In the equipment of a first-class modern cider mill nothing 
gives better satisfaction for the money expended than an 
apple elevator. The expense is a small matter compared with 
the convenience of having the mill so arranged that apples 
may be brought from any part by a perfect working elevator 
and carrier. Fig. 96 shows a section of an elevator. The 
chain runs over and is operated by a sprocket gear at the 
head with fast and loose pulleys. The scrapers are of wood, 



3 inches wide and 11 J inches long, bolted to lugs or projections 
on the chain. When run at from 50 to 70 revolutions per 
minute it will elevate from 5 to 10 bushels per minute. It 
works at an inclination or carries on the level. 

Fig. 97 shows the arrangement of a plant for making cider 
on a large scale, as described by Paul Hassack.* The apples 
are shoveled direct from the vehicle in which they are brought 
to the plant into the shed A, which is divided into not too 
large compartments. It is not advisable to pile the apples 
more than 3 to 4J feet high, as otherwise, when the weather is 

FIG. 97. 

unfavorable, the entire pile may become heated, and rotting, 
browning or the formation of acetic acid set in. Alongside 
the shed runs up to, underneath the roof of the press-room 
the elevator B, which conveys the apples to the grinder 0, 
the finely ground pulp falling into the receptacle D. The 
latter is furnished with a wooden tube E which can be closed, 
and leads to the press-room. By opening a slide a quantity 
of pulp just sufficient for one layer is allowed to run from the 

* ' ' Garungs-Essig." 


tube. F is a press-platform equipped with wheels and run- 
ning on a track. Upon this the pulp is uniformly spread, 
layer upon layer, each layer enclosed in a press cloth and a 
rack between each layer. According to the size of the press 
eight to twelve such layers are made into a cheese. The plat- 
form is then pushed under the press G, which is put in action 
by the motor M. In the commencement of the operation 
pressing has to be done carefully and not too suddenly to 
avoid bursting the press cloths, a more powerful pressure 
being applied only towards the end of the process when the 
juice runs off more slowly. In the meanwhile the next 
cheese is prepared. 

Testing the Must as to its Content of Acid and Sugar. With 
the exception of the grape but few varieties of fruit contain 
acid and sugar in such proportions and in such quantity (gen- 
erally too much acid and too little sugar) in that the must ob- 
tained from them will yield, when subjected to fermentation, 
a drinkable and durable wine. Wine whose content of acid 
exceeds 1 per cent, is too sour to the taste, and one containing 
less than 5 per cent, of alcohol cannot be kept for any length 
of time. Now as all fruit wines may be called artificial 
wines, and a natural product has consequently to be improved 
in order to make it more agreeable and wholesome, it is nec- 
essary to find ways and means by which the object can be 
accomplished in a manner most conformable to nature. For 
this purpose a knowledge of the content of acid and sugar in 
the fruit-must is required. 

To find the quantity of acid, compound a determined quan- 
tity, about 50 cubic centimetres, of must with about 5 grammes 
of purified animal charcoal,* boil the mixture about five 
minutes, and after cooling replace the exact quantity of water 
lost by evaporation. After shaking bring the whole upon a 

*Bone-black which is first boiled with solution of sodium carbonate for some 
time, and then after washing and extracting with hydrochloric acid is again 
washed and dried. 


coarse paper-filter in a glass funnel , and let it run off. Of the 
clear and generally colorless filtrate bring 6.7 cubic centimeters 
into a small beaker, add sufficient distilled water to form a 
layer of fluid 2 to 3 centimeters deep, and color red with 5 to 
10 drops of litmus tincture. While holding the beaker in the 
left hand and constantly moving it slowly in a horizontal 
direction, allow to run or drop in from a pipette, graduated in 
T V cubic centimeters and filled to the 0-mark, decinormal 
liquid ammonia until the last drop no longer changes the 
color of the fluid, and the place where the drop falls appears 
as if made clear by a drop of water. Now prevent a further 
flow of the ammonia by closing the pipette with the index 
finger of the right hand, and read off the quantity of ammonia 
consumed. The must examined contains as many thousandths 
of malic acid as cubic centimeters of liquid ammonia were 
required to color the fluid blue. 

Now if the examination shows that a must contains more 
than 8 parts, of acid per thousand, it is evidently too sour for 
the preparation of a palatable and wholesome fruit wine, and 
hence must be diluted to such a degree as to reduce the con- 
tent of acid to 6 or at the utmost to 8 parts per thousand. The 
calculation for this dilution is very simple, and consists in 
multiplying the acid per thousand parts present by 100 and 
dividing with the content of acid the wine is to have, the entire 
volume containing the desired acid per thousand being thus 
obtained. If, for instance, 18 parts per thousand of acid have 
been found in currant-must and the wine is only to show 6J 

parts per thousand, then 1QO X 18 .= 276.923, in round num- 


bers 277, i. e., 277 parts by measure of water have to be 
added to every 100 parts by measure of must. 

The content of acid in the must thus forms the initial point 
for the dilution in order to obtain, after fermentation, wine 
with a determined quantity of acid. To be sure the content 
of acid is sometimes increased by fermentation, some succinic 
acid, as previously mentioned, being formed and perhaps also 


some acetic acid. Sometimes, however, the content of acid 
decreases, which is very likely partially due to the water used 
for the dilution of the must containing earthy carbonates 
(lime, magnesia). It is, therefore, best not to have too much 
acid in the must, since, if the finished wine should be lacking 
in acid, it can readily be remedied by a suitable addition of 
tartaric acid, which is, however, not the case when it contains 
too much free acid. 

The determination of the sugar in must presents less diffi- 
culty and has already been fully described, hence there re- 
mains only the question how much sugar has to be added 
to the must in order to obtain a durable wine. 

Numerous analyses have shown that there is scarcely any 
grape wine which contains less than 7 per cent, by weight of 
alcohol, while in more generous wines the content rises to 12 
per cent, and more. Fruit-wines in order to possess good 
keeping properties should never show less than 7 per cent, by 
weight of alcohol, but there is no reason why they should not 
contain as much as 10 per cent. The advantage of the latter 
content is evident, the wines being thereby almost absolutely 
protected from spoiling, while they improve in aroma and 
taste, the various kinds of ether being only formed in wine 
rich in alcohol. 

The manner of calculating the quantity of sugar which has 
to be added to the must to give the wine the desired content 
of alcohol, w r ill be best shown by the following example : Sup- 
pose 135 liters of must which contains 4 per cent, of sugar are 
to be changed into must with 15 per cent, of sugar. 

For this purpose deduct from the weight of the must (which 
for the sake of simplicity we will consider equal to its volume) 
the weight of the sugar contained therein, multiply by the 
difference the per cent, of sugar the must is to contain, divide 
the product by 100 less the per cent, of sugar, and deduct 
from the quotient the per cent, of sugar already present in the 
must. For instance : 135 liters of must with 4 per cent, of 
sugar are to be changed into must with 15 per cent, of sugar. 


In 135 liters are contained 6.4 kilogrammes of sugar; 135 
5.4 = 129.6, which multiplied by 15=1944; this number 
divided by 100 15 = 85 gives 22.87. Deduct from this 5.4, 
and there remain 17.47 kilogrammes of sugar which have to 
be added to the must to give it 15 per cent, of sugar. 

For 325 liters of must with 3J per cent, of sugar to be 
changed into must with 20 per cent, of sugar the calculation 
would be as follows : 

(325 11.375)20 = 313.625 X 20 = 
100 20 ~8QT 

01 q ftOK 

^p D = 78.406 11.375 = 67.03 kilogrammes of sugar to 

be added. 

600 liters of must with 6 per cent, of sugar are to be changed 


into must with 22 per cent, of sugar : _l 36 = 117.4 


kilogrammes of sugar. 

The above examples will suffice to enable any one to exe- 
cute the calculations as required. 

The above calculations are based upon pure, anhydrous 
grape sugar, an article which does not exist in commerce, and 
hence has to be replaced either by commercial grape-sugar 
(glucose) or cane-sugar. Glucose, however, containing as a 
rule only 67 per cent, of anhydrous grape-sugar, 1 J times the 
quantity calculated above must be used, thus in the last ex- 
ample 176 kilogrammes instead of 117.4. With cane-sugar 
the proportion is the reverse, 171 parts by weight of cane-sugar 
being equal to 180 parts by weight of anhydrous grape-sugar; 
hence the per cent, of anhydrous grape-sugar calculated accor- 
ding to the above method must be multiplied by the fraction 
T y T or the factor 0.95. According to this, instead of the 117.4 
kilogrammes of grape-sugar in the last example, 111.73 kilo- 
grammes of cane-sugar will have to be used. 

Glucose. Pure glucose being identical with the sugar in 
sweet fruits, its use for sweetening fruit-juices intended for the 


preparation of wine is perfectly justifiable. With the dispute 
still carried on with honest weapons, whether it is permissible 
to assist nature with glucose when it fails to succeed in its labor 
of forming sugar in abundance, we have here nothing to do, 
since we know that the principal product alcohol or spirits of 
wine and almost the only one which passes into the wine by 
the fermentation of sugar, possesses the same properties whether 
it be formed from fruit-sugar or from glucose, and that neither 
one or the other can be injurious to health in the state of dilu- 
tion in which it presents itself in the wine, provided the latter 
be used in moderation. The must might be sweetened, as is 
frequently done, with cane-sugar which occurs in sugar-cane, 
in beet root, in sugar-maple, etc. But with the use of glucose 
we are one step in advance, since cane-sugar before fermenting 
is first resolved into a mixture of dextrose (glucose) and levulose. 
Commercial glucose is never pure, as it contains, besides 
about 15 percent, of water, of which about 6 per cent, is water 
of crystallization, about 18 per cent, of dextrin or similar sub- 
stances, and some gypsum. It has a white color, and is found 
in commerce packed in boxes into which it is poured while in 
a fluid state and gradually congeals to a hard mass. It is odor- 
less and has a faint sweet taste. On heating it becomes smeary 
and, finally melts to a yellowish syrup. Its content of anhy- 
drous fruit-sugar varies between 62 and 67 per cent. Inferior 
qualities contain either less sugar, or have a more or less dark 
color, and a disagreeable odor and taste. Independently of the 
content of sugar, glucose to be suitable for the preparation of 
wine, should show no odor or by-taste. 

The accurate determination of the content of pure sugar in 
glucose is connected with some difficulty. But few manufac- 
turers are provided with the necessary materials for making 
the analysis with Fehling's solution, and besides a certain 
amount of skill is required for obtaining accurate results by 
chemical tests. In consideration of this, Anthon of Prague 
has devised tables which are based upon the varying specific 
gravity of different saturated solutions of glucose, or rather 



upon its solubility in water. While 1 part of anhydrous grape- 
sugar requires for its solution 1.224 parts of water at 53.6 F., 
the foreign admixtures accompanying it dissolve in every pro- 
portion in water. Hence a saturated solution of glucose will 
show a greater specific gravity the more foreign substances 
it contains. In Anthon's tables is found the specific gravity 
and from this the content of anhydrous grape-sugar or glucose 
in the solution. In preparing a solution of starch-sugar for 
examination care must be had that it is completely saturated. 
Heat must not be used for effecting the solution, but a certain 
quantity of the glucose to be examined is rubbed in a mortar 
with one-half its weight of water at 53.6 F., and after pouring 
the thickish, turbid fluid into a tall beaker it is allowed to 
stand until clear. Anthon's table is as follows : 

Specific gravity 

Specific gravity 

of the solution 

of the solution 

saturated at 

Contains of foreign 

saturated at 

Contains of foreign 

53.6 F. i j 


53.6 F. 



per cent. 


25 per cent. 


2.5 " 


27.5 " 


5.0 " 


30.0 " 




32.5 " 




35.0 " 




37.5 " 




40.0 " 




42.5 " 




45.0 " 



Cider from Apples. The expressed juice from well-selected 
apples, properly prepared, forms a lively, sparkling liquor far 
superior to many wines. It is quite a favorite article of home 
production, nearly every farmer in regions where apples are 
grown, making his barrel of cider for use through the winter, 
but a large amount finds its way into the city markets. -A 
considerable quantity is also consumed in the shape of bottled 
cider, " champagne cider," "sparkling cider," and similar 
substitutes for, or imitations of, champagne wines. 


In England and France considerable quantities of cider find 
their way into the markets, though it is there, as here, largely 
an article of home consumption. Certain parts of those coun- 
tries are famous for the quality of their ciders, notably Nor- 
mandy, in France, and Herefordshire and Devonshire, in 

The Municipal Laboratory of Paris deduces from analyses 
of pure ciders from different parts of France the following as 
a type of composition for pure ciders : 

Alcohol, per cent, by volume 5.66 

Extract, per liter, at 212 F. . . 30.00 

Ash 2.80 

Other analyses of pure ciders, from different parts of France, 
published by M. G. Lechtartier, have shown great variations 
from this type, and show the necessity for the examination of 
large numbers of samples from various parts of the country 
for the establishment of a proper standard of analysis. 

Analyses of Ciders by the United States Agricultural Depart- 
ment. The samples for the investigation were purchased in 
the city in the same manner as samples of wine and beer : 




Serial No. 





Specific gravity. 


Alcohol by volume. 

Total solids. 







Carbonic acid. 


Well-fermented ciders. 
Draft cider (" extra dry ") ... 
Bottled cider, known to be 




p. ct. 









p. ct. 







Bottled cider 



1 0007 


7 83 





6 1 

Bottled " extra dry russet " 










" Champagne cider," bottled. 
"Champagne cider," bottled. 
4 'Sparkling cider," bottled. . 















1 0154 

5 17 

6 45 

3 88 




"Sweet" or incompletely 
fermented ciders. 
Draft cider 











1 0516 



9 59 




34 2 

" Sweet " cider (draft) 
Do .. 



1 0203 

3 46 

4 33 

3 84 






24 2 




1 0552 







48 5 




1 0355 








1 0455 

1 40 

1 76 

8 17 




1 A circumstance arising after the samples had been thrown away seemed to throw con- 
siderable doubt upon the determinations of sugar, which were made by an assistant, and 
the entire set had to be thrown out. 

2 Determinations of the carbonic acid in three different bottles gave the following results: 
.728, .654, .482. 

The choice of the varieties of apples is of great importance 
in the manufacture of cider. All apple juice will not make 
equally good cider, even if it is equally well handled. It is not 
always the best flavored apple or the best tasting juice that will 
make the best cider. Indeed, as a rule, the best cider is made 
from apples which are inferior for table use, such as the crab- 
apple and the russet. But it is a pretty general rule that the 
most astringent apple will make the best cider. This astrin- 


gency is due to an excess of tannin. While a portion of this 
tannin is changed to sweetness, a considerable portion remains, 
which serves to render the cider more easily and thoroughly 
clarified and to make it keep better. The tongue alone being, 
however, not sufficient to detect the tannin in apples, the fol- 
lowing will serve as a reliable test: Express the juice of a 
few apples and add a few drops of isinglass, which combines 
with the tannin and forms a precipitate. From the greater 
or smaller quantity of this precipitate a conclusion can be 
drawn as to the quantity of tannin present. The specific 
gravity of the juice, which may vary between 1.05 and 1.08 
should be determined. The greater the specific gravity of 
the juice the better the respective variety of apple is for 
making cider. According to these directions, the raw mate- 
rial should be selected, though in most cases it will be 
necessary to use a mixture of different varieties. In France, 
for a quality of cider which will keep well, the apples are 
mixed in the following proportions : f bitter-sweet and J- 
sweet apples. If a sweet cider is wanted not intended to be 
kept for a long while, J bitter-sweet and f sweet apples are 

The apple, like every other fruit, consists of solid and fluid 
constituents. The solid constituents are the skin, core, seeds, 
as well as the pulp in the cells of which the fluid constituents 
the juice are enclosed. The solid insoluble constituents 
consist chiefly of cellulose, albuminous substances, pectose, 
mucilage and other less insoluble substances. The average 
proportion between solid and insoluble substances and juice is 
of course subject to wide fluctuations, according to the nature 
of the soil, season of the year and degree of ripeness. 

Generally speaking, the composition of the apple may on an 
average be given as follows : 

Solid substance (pulp) . . 3 to 7 per cent. 

Juice . . . . 93 to 97 per cent. 


The juice constituents contain about : 

Water 80 to 88 per cent. 

Sugar . . . 9 to 18, even up to 24 per cent. 

Acid 0.6 to 1.8 percent. 

Extractive substance . . 1.3 to 3 per cent. 

The juice pressed from apples is called must or cider. The 
sugar in the must is a mixture of different kinds of sugar 
varying greatly in proportion, and consists of dextrose, laevu- 
lose and sucrose. The acid of the apple, as well as that of the 
pear, consists of malic acid, and frequently also of small frac- 
tions of citric acid ; tartaric acid, however, is never present. 
Must with less than 5 per cent, of acid has an insipid taste, and 
consequently an addition of artificial malic or citric acid has 
to be made to musts augmented with water in order to 
improve the taste. On the other hand, when the must con- 
tains too much acid, the latter cannot be fixed with calcium 
or potassium carbonate, but should be reduced by the addition 
of water and sweetening with sugar. The extractive substances 
of apple-must consist of tannin 0.2 to 0.6 per cent., pectin 
bodies 4 to 4.5 per cent., albuminous substances and mucil- 
age, various soluble mineral substances and a series of gums 
thus far undetermined. 

The apples intended for the preparation of cider should be 
allowed to attain complete maturity, which is recognized by 
their color, the dark hue of the pips, little specks covering the 
skin, and by the sharp and agreeable ethereal odor emanating 
from them. In fact they should be allowed to remain on the 
trees as long as vegetation is active or until frosts are appre- 
hended, for thus the conversion of the starch into sugar is best 
effected and their keeping better secured than by storing. 
They should be gathered by the hand to prevent bruising and 
coming in contact with dirt. They are then placed in piles and 
allowed to sweat. This sweating process has a tendency to ripen 
the fruit and make it uniform, thereby improving the flavor 
as well as the quality and strength of the cider in consequence 


of the apples having parted with six or eight per cent, of water. 
The strongest cider is made from apples containing the smallest" 
percentage of juice, and, in its aqueous solution, the largest 
proportion of saccharine matter. If the weather be fine, the 
piles may be exposed in the open air upon clean sod or where 
this is wanting upon boards or linen cloths, but under no cir- 
cumstances should the apples be placed upon the bare ground 
or upon straw, as they contract an earthy or musty taste which 
is afterwards found in the cider. 

After sweating and before being ground the apples should be 
wiped with a cloth to free them from exudation and adhering 
particles of dirt, and if any are found bruised or rotten they 
should be thrown out. Ripe, sound fruit is the only basis for a 
good article of cider, and the practice of mixing rotten apples 
with the sound, as is frequently done and even advocated by 
some, cannot be too strongly condemned. Mellow or decay- 
ing apples have lost almost all their perfume, a certain quan- 
tity of water by evaporation, and a large portion of their sugar. 
Rotten apples yield a watery liquid of an abominable taste, 
which prevents the cider from clarifying and accelerates its 

The apples being wiped, sorted, and, if necessary, mixed in 
the desired proportions, are now brought into the grinder and 
reduced to an impalpable pulp. By this operation the numer- 
ous infinitesimal cells of the apple should be thoroughly broken 
up so as to permit the free escape of the juice when under 
pressure, and the machine which accomplishes this most 
effectually is the best for the purpose. If the cells are not 
thoroughly torn asunder, their tendency is to restrain and 
hold, as it were, in a sack much that otherwise would escape. 
As regards the crushing of the seeds there is a diversity of 
opinion, some holding that they communicate to the cider a 
disagreeable bitterness and acidity, while others consider them 
as rendering the cider more alcoholic and making it keep 

According to M. Bergot, for cider of superior quality it is 


preferable not to crush the seeds, because the diffused odor of 
the essential oil would undoubtedly injure the fine taste of cer- 
tain notable products. For ordinary cider the crushing of the 
seeds will, on the other hand, be of advantage, because their 
essential oil helps to give to the cider the bouquet which it 
otherwise lacks. For cider intended to be converted into 
brandy the seeds must, however, be crushed. The grinder 
should be cleansed with hot water every evening, or at least 
every third' day. 

The treatment to which the pulp obtained by grinding is 
subjected varies according to the color the cider is to have. 
Where the consumer prefers a pale-yellow color the pulp must 
at once be pressed, while for a darker color it is allowed to 
stand 12 to 18 hours. 

The next step in the operation is pressing. The various kinds 
of presses, racks, and manner of laying up the cheese have 
already been described. The primitive custom of laying the 
cheese was to lay upon the platform of -the press a quantity of 
straw, upon which a quantity of pomace was placed, and the 
edges secured by laps of straw, thus alternating straw and 
pomace until the pile was complete. The object of using the 
straw was to hold the mass together while it was being sub- 
mitted to pressure, and also to serve as a means of exit for the 
cider. An improvement was in the substitution of hair-cloths, 
and within the past few years the adoption of the cotton press- 
cloth and racks to hold the pomace in laying up the cheese 
for the press. The racks have already been described. The 
press-cloth is woven from yarn made expressly for the purpose 
and is of equal strength in warp and filling. The use of straw 
in laying up the cheese should be entirely discarded, as the 
slightest mustiness imparts an unpleasant odor^to the cider. 

The pressure applied to the cheese should be slow at starting 
and then gradually increased until finally the full force is 
applied. The juice as it comes from the press runs through a 
fine hair-sieve into a receiver. With a good press about 65 to 
75 per cent, of juice will be obtained. 


After the cider has been extracted and the cheese removed 
from the press the pomace may be utilized for the manufacture 
of vinegar, as previously described. In France it is, however, 
used for the manufacture of the small cider. The method is as 
follows: After the extraction of the pure cider by the first 
pressing, the pomace is taken from the press, and after adding 
12 litres of water for every hectoliter of apples used, the mass 
is allowed to macerate 15 to 20 hours, care being had to stir 
every two or three hours. Then this pulp is put a second time 
under pressure and a quantity of juice extracted equivalent to 
the amount of water added. 

Extraction of the juice by diffusion. Diffusion, which gives 
such excellent results in the extraction of sugar-beets, has also 
been applied to extract the soluble constituents of the apple. 
In practice this method might be suitable for persons having 
no cider press and only a small quantity of apples to handle. 
The quality of cider is nearly equal to that obtained by three 
pressures, and the juice obtained is almost as rich as that 
yielded by the press. 

Successful experiments in expressing the juice of the grape 
by means of the centrifugal would indicate that the same 
method might also be applied to apples. 

. The freshly-expressed apple-juice is either sold as sweet 
cider or subjected to fermentation. Fermentation in sweet 
cider is retarded by pasteurizing, carbonating, or the addition 
of preservatives. The objections urged against pasteurizing 
or sterilizing fresh apple-juice are that a "cooked " taste is 
added to the juice, and that it is impracticable to hold the 
juice sterile for more than a limited period. Experiments to 
develop a method for sterilizing apple-juice in wooden, tin and 
glass containers have been made by H. C. Gore,* and his 
investigations demonstrate that only a slight cooked taste is 
produced by the heat treatment required, and that it is a sim- 

* U. S. Department of Agriculture, Bureau of Chemistry, Bulletin No. 118. 
" Unfermented Apple-juice." 


pie matter to protect the juice from inoculation after steriliz- 
ing. A summary of these investigations is here given : 

(1) " The experiments show conclusively that it is possible 
to sterilize apple-juice in wooden containers, the product re- 
maining sound for at least six months under actual observa- 
tion. The precautions which must be taken to insure this are 
as follows : First paraffin the containers on the outside, then 
sterilize, and fill with juices heated to between 149 and 158 
F. (65 to 70 C.) ; seal, taking measures to relieve the vacuum 
produced by the contraction of the juice on cooling by filter- 
ing the air through cotton. Twenty-four 10-gallon kegs suc- 
cessfully stood a severe shipping test, showing no loss due to 
fermentation of the juice. The juice so prepared was found 
to be palatable, and acceptable as a summer drink. 

(2) " It is demonstrated that apple-juice can be successfully 
sterilized in tin containers, using the type of tin can sealed by 
the mechanical process, excluding all metals from contact 
with the juice except the tin of the can. Where lacquered 
cans are used the contamination with tin was reduced about 
one-half. Apple juices were canned and sterilized by heating 
in a hot water-bath, up to the temperature of 149 F. (65 C.) 
for a half hour, and then allowed to cool. These juices pos- 
sessed only a slight cooked taste due to the heating and re- 
tained much of their distinctive apple flavor. It was found 
that from finely flavored apple-juice a first-class sterile product 
could be made, while a poorly flavored apple-juice yielded an 
inferior product. The process conditions mentioned were not 
quite thorough enough to sterilize all of the varieties canned. 
A slight increase in the temperature or time of processing, or 
both, should be made, the temperature not to exceed 70 C. 
(158 F.) in any case. 

(3) " The best treatment for sterilizing in glass was found 
to consist in heating for one hour at 149 F., or for one-half 
hour at 158 F. Heating for one hour at 158 did not pro- 
duce marked deterioration in flavor, a half hour being allowed 
in all cases for the juice to obtain the temperature of the 


(4) " It was shown that the great bulk of the insoluble 
material naturally contained in apple-juice can be removed 
by means of a milk separator." 

These investigations extended also to carbonating fresh 
apple-juice and the conclusions arrived at are as follows: 

" It is possible to carbonate the juice slightly before canning 
or bottling, thus adding a sparkle to the product. A flavor 
foreign to fresh apple-juice is also added, however, and un- 
carbonated sterile juice will resemble fresh apple-juice more 
closely. Carbonating by the addition of water charged with 
carbon dioxid was considered by some to injure the flavor, 
lessening the characteristic fruit flavor by dilution. In the 
opinion of others a heavy, rich juice was improved both by 
the charge of carbon dioxid and by the consequent dilution. 
Experiments indicated that the danger of contamination by 
mold growths was lessened by maintaining an atmosphere of 
carbon dioxid above the surface of the juice after opening." 

When apple-juice is sold in bulk a small amount of benzo- 
ate of soda is, as a rule, added to retard fermentation, one- 
tenth of 1 per cent, being tolerated by regulation in the United 
States. H. C. Gore's investigations demonstrated that benzo- 
ate of soda in quantities varying from 0.03 to 0.15 per cent., 
while it checks the alcoholic fermentation, allows other organ- 
isms to develop notably the acetic acid ferment whereby 
the palatability of the product as a beverage is destroyed. 

H. C. Gore has also investigated the cold storage of apple 
cider,* and the summary of the results of these investigations 
is here given : 

(1) " Ciders prepared from apples free from decay chilled 
rapidly to the freezing-point immediately after pressing, and 
then held in cold storage at C. (32 F.) remained without 
noticeable fermentation for a period of from thirty-six to fifty- 
seven days, an average of fifty days for the Tolrnan, Winesap, 

* U. S. Department of Agriculture, Bureau of Chemistry, Circular No. 48, 
"The Cold-Storage Apple Cider." 


Yellow Newtown, Rails, Gilpin, and Baldwin varieties, and of 
eighty-three days in the case of the Golden Russet, Roxbury 
Russet, and Kentucky Red. 

(2) " These ciders were held for a period of from ninety to 
one hundred and nineteen days, an average of ninety-nine 
days for the first six varieties and of one hundred and twenty- 
five days for the last three, before they fermented sufficiently 
to be considered as becoming " hard " or " sour." 

(3) " The ciders were found to have suffered no deteriora- 
tion (with the exception of the Tolman), but rather had be- 
come more palatable during storage." 

The apple-juice to be fermented should be tested with a 
must-spindle or densimeter as to its content of sugar. A good 
quality of juice will generally range from 10 to 14 per cent. 
If less than 10 per cent, the juice will not make a cider that 
will keep, though, if the flavor in other respects is all right, a 
beverage for immediate use may be produced from it. 

When the juice has been tested and, if found wanting in 
saccharine strength, corrected by the method previously given, 
the next step in the operation is fermentation. For this pur- 
pose the juice is brought into casks. Regarding the size of 
the latter it may be said that, as a rule, the juice ferments 
more uniformly and more steadily, and retains the carbonic 
acid better with the use of larger casks, though it develops 
somewhat more slowly than in smaller containers. For the 
production on a large scale of cider of first-rate quality the 
use of large casks can, therefore, be recommended. However, 
if the cider is to be used for daily consumption, and perhaps 
be directly drawn from the yeast, smaller containers are pre- 
ferable, there being less danger of the cider becoming mouldy 
or sour. The casks should be scrupulously clean, and new 
ones must be freed by steaming or washing with hot water 
from all extractive substances, otherwise the cider will acquire 
a disagreeable taste and dark color. 

In many places the fermentation-casks are filled by means 
of a power pump which delivers the juice to the receptacles 


placed in adjacent rooms or in another building. When the 
press-room is over the fermentation room, filling is accom- 
plished by gravity. Hose-pipes are largely used for this work, 
but brass or copper must be used for all metal fittings. The 
less the juice comes in contact with the air after it leaves the 
press the less liable it is to be contaminated with various un- 
desirable organisms. The pumps and pipes must be kept 
scrupulously clean. 

In Fig. 97 p. 386 the juice running off from the press 
through the pipe H is freed from the principal particles of 
pulp in the box J, which is fitted with two or three wire- 
sieves of different fineness. This box is located above the 
collecting vat K. 

The fresh juice having been brought into the casks, fermen- 
tation is still left in many places to the organisms normally 
present on the fruit and those which may at the time of grind- 
ing and pressing enter the juice from contact with the air, the 
machinery and the vessels. Fermentation in this case does 
not always progress as norn^lly and favorably as required 
for the production of a sound, palatable and durable cider. 
The various races of yeast present on the apple possess but 
little fermenting power and the elliptic wine yeast (sacchar- 
omyces ellipsoidus) which has to be taken chiefly into account, 
being generally represented only in very small quantities, is 
stifled and readily suppressed. It is a well-known fact that, 
generally speaking, apple juice ferments completely only with 
difficulty. This appears to be due to the fact that the nat- 
ural cane sugar, which is frequently present in considerable 
quantities in apple and pear juices, is fermented with great 
difficulty by the organism normally present on the fruit, and 
to assure the ascendancy of the true yeasts and thus give them 
the control of the entire process of fermentation, the practice 
of sowing the juices with pure cultures of yeast has been intro- 
duced. In Germany all the important factories employ these 
cultures, which are obtained in small flasks from the Royal 
Pomological School at Geisenheim. With the use of pure 


, culture of yeast it is best to add it to a smaller quantity of 
sterile juice previously heated to 140 F. and then cooled to 
68 F. When fermentation in the sterile fluid is most vig- 
orously developed i't is added to the juice to be fermented. 

Another cause of the difficult fermentation of apple juice is 
the frequent want of nitrogenous combinations required for 
the nutriment and propagation of the yeast. This may be 
remedied by the addition of 20 grammes of ammonium tar- 
trate or ammonium chloride per hectoliter of juice ; in place 
of it the same quantity by weight of ammonium phosphate or 
ammonium carbonate may also be used. Such an addition 
should also be made with the use of pure culture of yeast. 

The first or tumultuous fermentation of the apple juice is in 
some places effected in open vats, this method being generally 
preferred with juice not previously strained, so as to be able 
to remove during fermentation the insoluble constituents of 
the must which are forced to the surface. 

When, however, the must has been purified by straining or 
filtering over thoroughly washed sand, fermenting in casks is 
preferable. The casks are fillea about three-quarters full and 
equipped with a ventilating bung to prevent the entrance of 
germ-laden air. There are various constructions of ventilating 
bungs but the principle is in all cases the same, namely, to 
allow the escape of the excess of carbonic acid and prevent the 
entrance of air. The best protection of the must is the car- 
bonic acid developed during fermentation, because, on the one 
hand, neither mould or acetic acid formation can appear for 
want of oxygen, and, on the other, the exciters of these decom- 
positions cannot develop in an atmosphere of carbonic acid. 
Care should, therefore, be taken that until fermentation is fin- 
ished and the cask has been entirely filled and bunged, an 
atmosphere of carbonic acid always lies over the cider in the 
empty space of the cask. 

The fermentation funnel or ventilating funnel, Fig. 98 which 
is largely used in Germany, is a simple device for controlling 
the air. It is generally made of pottery or porcelain, though 


it can also be constructed of metal, for instance, aluminium. 
It consists of two parts, the actual funnel c with the tapering 
pipe d, which is secured air-tight in the bung-hole and is filled 
half-full with water, and a cup-like vessel b, which is placed 
over the elongated portion of the pipe of the funnel. The 
carbonic acid escaping from the cask passes through the pipe 
into the cup b, forces back the water at o and escapes at e from 
the open portion of the funnel, the entrance of air being on 
the other hand prevented by the water. 

The first or tumultuous fermentation runs its course, accor- 
ing to temperature and other conditions, in two to four weeks, 

the temperature being under otherwise, normal conditions, the 
most important factor. The higher it is , the more energetic- 
ally fermentation sets in and the more rapidly it runs its 
course. While formerly a not too tumultuous course of the 
first fermentation was not desired by many manufacturers and 
the temperature was kept relatively low, most of them have 
now arrived at the conclusion that as energetic a course as 
possible of the first fermentation is the best guarantee for a 
good product, and the temperature for the first stage of fer- 
mentation should be at least between 59 and 68 F. When 
the first fermentation has run its course, which is recognized 
by the cessation of the hissing sound made by the carbonic 


acid gas, the cider is drawn off from the sediment into clean, 
unsulphured casks, furnished with a ventilating bung. The 
casks are placed in a cellar or a cool room having a tempera- 
ture of 40 to 50 F., and the cider is left to the second or after 
fermentation. The casks should be constantly kept full, and 
abrupt variations in the temperature carefully avoided and 
provided against. Generally speaking, the more energetically 
the first fermentation has run its course, the more quietly the 
second fermentation will progress, and vice versa. By the 
second fermentation, the remainder of the sugar is decomposed, 
there is but a slight evolution of carbonic acid, the yeast as 
as well as the albuminous substances in the must settle on 
the bottom, and the cider becomes more or less clear. 

When the second fermentation has progressed to the desired 
degree, the cider is drawn off into other casks and fined. Ac- 
cording to one method this is done with isinglass, 1J ozs. of it 
being allowed for each cask. This quantity is dissolved in 1 
pint of cider over a moderate fire, and the solution when 
cold, poured with constant agitation into the cask. Drawing 
off may be commenced after eight days. 

A better method of clarification, which at the same time in- 
creases the purity of taste of the cider, is as follows : For each 
barrel of 30 gallons, take 4 Ibs. of fresh wheat bran, and, after 
washing it twice in hot water to remove all soluble substances, 
press out thoroughly. Now dissolve about 2 drachms of alum 
in a bucketful of hot water and. pour the solution upon the 
bran. After 6 to 8 hours take the latter from the alum water 
and press as before. The bran is best used before the cider is 
racked off for the third and last time. Stir it into the cider, 
and then draw off the latter through a fine strainer into the 
actual storage barrel. The cider first passing through the 
strainer is generally somewhat turbid, and must be poured 
back until it runs off clear. 

In France, the cider is generally clarified by dissolving 2 ozs. 
of catechu in 1 quart of cider and adding the solution to 100 
quarts of cider, with constant stirring. The tannin thus added 


precipitates the albuminous matters, the result being a clear 
cider which will not blacken in the air. 

It is always advisable before fining large quantities of cider 
to make a clarifying experiment on a small scale, the content 
of tannin in the fluid being frequently so small that the clari- 
fying agent added is ineffectual. In such cases a small addi- 
tion of tannin in the form of an alcoholic-aqueous solution 
previous to the addition of the clarifying agent can be recom- 
mended. However, as a perfectly bright product is not always 
obtained by fining, filtering will ha^ to be resorted to. Fil- 
ters of various types, such as bag filters, cellulose filters and 
asbestos filters are in use for this purpose. Filtering cider 
appears to be a process much more difficult than filtering wine 
made from grapes and should be avoided if possible. The 
reason for this is the presence of mucilaginous substances in 
the liquor. 

Pared apples, if used for the production of cider, yield a 
product poor in aroma. Washing the apples in washing 
machines of special construction previous to grinding and 
pressing is of great advantage for the production of fine must 
and cider. Fairly good products can be obtained from dried 
American apples, the cheapest brands (waste, parings, cores) 
of which can be used for the purpose. 

Cider intended for export must be made somewhat richer 
in alcohol, which is generally done by adding sufficient 
French brandy to increase its content of alcohol 2 per cent. 
Sometimes, also, J Ib. of sugar for every 2 quarts of juice is 
added during fermentation. For shipping to tropical countries 
experiments might be made with salicylic acid, adding it in 
the same proportion as to beer, which is for beer sent in 
barrels f oz. for 100 quarts, and for bottled beer, J oz. 

There are several methods of improving the taste of cider, 
but they are rather questionable, because tastes differ, and 
what might be considered an improvement by one would be 
declared a defect by another. A favorite method of improve- 
ment is as follows : For 45 gallons of cider measure off 3 quarts 


of French brandy and mix it with the following substances? 
all finely powdered : 0.7 drachm of bitter almonds, 0.7 drachm 
of mace, and 7J drachms of mustard-seed, and finally 3J 
drachms of catechu, previously dissolved in water. Pour this 
mixture into the cider and shake the barrel frequently during 
the next 14 days. Then allow it to rest three or four months, 
and should it then not run off clear when tapped, clarify it 
with 1 J oz. of isinglass or the whites of a dozen eggs. If the 
color of the cider is to remain pale yellow, catechu cannot be 
used, and instead of isinglass or white of egg, skimmed milk 
is to be used for clarification. For a reddish color, which is 
sometimes desired, use If drachms of powdered cochineal in 
place of the catechu. 

Sometimes cider is prepared in the same manner as other 
fruit-wines. In this case J Ib. of sugar is added to every quart 
of juice, and the latter is allowed to completely ferment in the 
same manner as grape wine. According to another direction, 
add to every 2 quarts of juice, 2 Ibs. of white sugar, and boil 
as long as scum is formed ; then strain through a fine hair- 
sieve and allow to cool. Now add a small quantity of yeast, 
stir thoroughly, let the whole ferment three weeks, and after 
clarifying rack off into bottles. 

Red apple wine, or, as it is frequently called, red wine from 
cider, is prepared as follows : Boil for 2 hours 50 quarts of 
apple juice, 27 Ibs. of honey, 1 oz. of tartar, 6 Ibs. of comminuted 
red beets, and 3, Ibs. of brown sugar. Let the fluid completely 
ferment, and if no apple juice is on hand to fill up the barrel 
during this process, use solution of sugar. When fermentation 
is finished, pour a mixture of 1 quart of French brandy and 
about 1 drachm each of pulverized cinnamon and ginger into 
the barrel. After three months clarify the wine and rack off. 

In his treatise on " Cider," Dr. Denis-Dumont gives the fol- 
lowing directions for bottling cider : The cider is to be bottled 
at three distinct periods. It should never be bottled before 
the tumultuous stage of fermentation is entirely completed and 
the liquid clarified. 


First period. At the termination of the tumultuous fermen- 
tation, the cider still contains considerable sugar. Fermen- 
tation continues in the bottle and produces in a few weeks a 
large quantity of carbonic acid. In order to prevent the bottles 
from being broken by the pressure, champagne bottles should 
be selected, and care taken to have them stand upright until 
the development is considerably reduced. The bottles are 
then laid on their side, as otherwise the cider would cease to 
be sparkling. This cider has to be kept for a number of years, 
it being good to drink only when old. 

Second period, when fermentation is more advanced, about 
six weeks or two months after the first period. Mineral water 
bottles are strong enough to hold this cider, it liberating less 
carbonic acid than the preceding. The bottles are left in an 
upright position for a few weeks only. This cider has a good 
flavor and is fit to drink much sooner than the preceding. It 
keeps for a long time. 

Third period, when fermentation is complete or almost so, 
any quality of bottles may be used, a great deal less of car- 
bonic acid being developed than in the preceding cases. The 
bottles should be laid down immediately after filling, in order 
to retain the carbonic acid which will still be developed. This 
cider is not sparkling ; it is, however, lively, strong, and has a 
fine flavor. 

The bottles should, in every instance, be well corked, and 
the corks, for the sake of safety, tied. The cider is very good 
when kept in small bottles, better in quart bottles, and best in 
jars holding two quarts. A few moments before opening a 
bottle of sparkling cider, it is advisable to provide a minute 
opening for the escape of the gas by piercing the cork with a 
fine punch. As soon as the tension of the gas has become 
sufficiently weak, the cork is allowed to blow out in the same 
manner as with champagne. Without this precaution, most 
of the cider might be thrown up to the ceiling. 

In the island of Jersey, where the manufacture of cider is 
carried on in a very rational manner, the juice as it comes from 


the press is allowed to ferment in large open vats placed in a 
cellar having a uniform temperature of from 53 to 59 F. On 
account of the large surface presented to the air, tumultuous 
fermentation soon sets in, and in about four or five days, or at 
the utmost a week, fermentation is over. The liquid is then 
drawn off in barrels, thoroughly cleansed and sulphured, in 
which fermentation continues slowly. These barrels are not 
entirely filled, and when the development of carbonic gas has 
proceeded so far that the flame of a lighted candle introduced 
by the bung-hole is extinguished, the liquid is drawn off into 
other barrels sulphured like the first. This transfer from one 
set of barrels to another is continued until no escape of gas is 
perceptible, i. e., until fermentation is quite complete. 

Prepared in this manner the cider will keep perfectly good 
for several years, and stand transportation by sea without any 

Devonshire cider is made from a mixture of one-third of 
bitter-sweet apples with a mild sour. These being gathered 
when thoroughly ripe are allowed to undergo the sweating pro- 
cess before grinding. The cider is then pressed in the usual 
manner and strained through a hair-sieve into hogsheads, 
where it remains for two or three days previous to fermenting. 
It is then drawn off into clean casks to stop the fermentation, 
but if this is very strong only two or three gallons are first put 
in, and after burning cotton or linen rags saturated with sul- 
phur in the cask, thoroughly agitated. This completely stops 
fermentation in that quantity and usually checks it in the other 
portion with which the cask is then filled up. In a few weeks 
the cider becomes very fine. If this be not satisfactorily ac- 
complished by the first operation, it is repeated until fermen- 
tation is completely checked and the cider is in a quiet state 
and in a proper condition for drinking and bottling. 

Champagne-cider. The manufacture of this beverage has 
become quite important it resembling the ordinary but more 
expensive champagne-wine, and being frequently sold as such. 
Since the devastation of the vineyards by the phylloxera, a 


large trade in the spurious champagne-wine is carried on in 
France. This champagne-cider if sold under its right name 
is an excellent beverage. It is prepared as follows : To 50 
gallons of apple-juice add 12 quarts of brandy and 14 Ibs. of 
sugar or honey. Mix the whole thoroughly, and allow it to 
ferment for one month in a cool place. Then add about 4 
drachms of orange-blossom water, and clarify with 2 quarts 
of skimmed milk. The champagne is now ready and is racked 
off into bottles, into each of which a small piece of white sugar 
is thrown, and the corks of which are wired. The duration 
of fermentation has been stated as one month. It may, how- 
ever, last a few days more or less, it being entirely a matter of 
observation when the most suitable time for racking off has 
arrived. No more rising of bubbles of gas should be observed, 
but fermentation must not be completely finished. 

According to another process, 40 quarts of fermented apple- 
juice are mixed with 2 quarts of solution of sugar, J quart of 
rectified alcohol and 2 ozs. and 4 drachms of pulverized tar- 
tar. The mixture is allowed to stand 24 hours and then 
racked off into bottles, each bottle receiving a drachm of bicar- 
bonate of soda. Cork and wire. 

Another process consists in bringing into a vat 40 quarts of 
apple-juice, 5 Ibs. of white sugar, J Ib. of tartar, 1 pint of rec- 
tified alcohol, j- pint of yeast and 1 oz. and 2J drachms of 
acetic ether. Shortly before fermentation is finished the mix- 
ture is drawn off into bottles, each of which has previously 
been provided with a small piece of sugar. Clarification with 
isinglass, white of egg or skimmed milk must, of course, pre- 
cede the drawing off into bottles. The bottles must be thor- 
oughly corked and wired in the same manner as genuine 
champagne, and laid in a cool cellar. 

Cider serves frequently as a basis for artificial wines, genuine 
Burgundy, sherry or port-wine, prepared from cider mixed 
with suitable substances, being frequently served even in first- 
class hotels. Nothing could be said against these beverages if 
they were sold under their proper names, because they consist 


of harmless substances, which cannot always be said of the 
genuine wines, they being only too frequently adulterated with 
substances injurious to health. 

Burgundy. Bring into a barrel 40 quarts of apple juice, 5 
Ibs. of bruised raisins, Ib. of tartar, 1 quart of bilberry juice 
and 3 Ibs. of sugar. Allow the whole to ferment, filling con- 
stantly up with cider. Then clarify with isinglass, add about 
1 oz. of essence of bitter almonds, and after a few weeks draw 
off into bottles. 

Malaga Wine. Apple juice, 40 quarts ; crushed raisins, 10 
Ibs.; rectified alcohol, 2 quarts; sugar solution, 2 quarts; 
elderberry flowers, 1 quart; acetic ether, 1 oz. and 2 drachms. 
The desired coloration is effected by the addition of bilberry 
or elderberry juice ; otherwise the process is the same as given 
for Burgundy. 

Sherry Wine. Apple juice, 50 quarts; orange-flower water, 
about 2 drachms ; tartar 2 ozs. and 4 drachms ; rectified alco- 
hol, 3 quarts; crushed raisins, 10 pounds; acetic ether, 1 oz. 
and 2 drachms. The process is the same as for Burgundy. 

Claret Wine. Apple juice, 50 quarts ; rectified alcohol, 4 
quarts ; black currant juice, 2 quarts ; tartar, 2 ounces and 4 
drachms. Color with bilberry juice. The further process is 
the same as for Burgundy. 

Diseases of Cider. Ciders are subject to diseases which may 
be due to the bad quality of the apples used, a faulty method 
of manufacture, or bad management in the cellar. 

Badly fermented cider, especially such as has merely passed 
through the stage of tumultuous fermentation, or has been 
acidified by contact with the air, is liable to produce serious 
disorders. The first, says Dr. E. Decaisne, being heavy and 
indigestible, inflates the intestines and produces diarrhoea ; the 
second, though of a sweet taste and a piquant and agreeable 
flavor, does not quench the thirst, but excites the nervous 
system and produces flatulency ; the third, which is really 
spoiled cider, causes inflammation of the intestines by the 
large amount of malic and acetic acid it contains. When in 


the production of cider, water containing organic matter has 
been used, putrid fermentation is produced in the mass, the 
products of which impart some very deleterious properties to 
the cider. 

Acidity in cider may be due either to an excess of malic acid 
or of acetic acid. 

Some ciders contain too much malic acid when manufac- 
tured from apples not sufficiently ripe, or when, in mixing the 
apples, too large a proportion of sour apples has been taken. 
In both these cases the acidity may be neutralized by adding 
to the apple-juice 3 ounces and 8 drachms of potassium tartrate 
per 22 gallons. Sometimes there is an excess of acetic acid, 
due to the oxidation of the alcohol by long contact with the air. 
This defect is difficult to remedy. It might have been pre- 
vented by means of a thin coat of olive oil, as previously men- 
tioned, or by hermetically closing the bungs. The acidity will, 
however, disappear by putting in the bottles a pinch of bicar- 
bonate of soda. It must, however, be done immediately on 
detecting the defect. 

Viscosity or greasy appearance of cider is recognized by the 
cider becoming stringy, viscous and greasy, and is due to too 
great an abundance of gummy substances in the fruit, a lack 
of tannin, and finally to defective fermentation. In order to 
check this malady from its first appearance, add to every 228 
quarts of the cider 1 pint of alcohol or 2 grammes of catechu 
dissolved in 3 quarts of water. Cider may be prevented from 
turning viscous by the addition of sugar to the juice when it 
comes from the press, fermentation being thereby promoted. 

The cause of cider turning black is an excess of oxide of iron, 
which, on coming in contact with air, becomes a peroxide and 
gives the beverage a brown color. The oxide of iron may 
have been introduced into the cider either by the water used 
in making it, or by fruit grown on ferruginous soil. By mix- 
ing such cider with 12 drachms of powdered oak bark per 22 
gallons, a quantity of tannin is introduced which combines 
with the iron to an insoluble product that settles on the bot- 
tom of the barrel. Tartaric acid may also be used. 


Turbidity or lack of clarification of cider is caused by too 
small a quantity of sugar in the juice, or by imperfect 

In rainy seasons the apples ripen imperfectly and contain 
but little sugar. Cider prepared from such fruit generally re- 
mains turbid. During seasons in which abrupt changes of 
temperature take place, and also when cold weather sets in 
very early, fermentation does not progress well, and clarifica- 
tion is imperfect. When the cider remains turbid after the 
first racking off, add a solution of 2 Ibs. of sugar in 1 gallon 
of water to every 132 gallons of the liquid. This sugar be- 
comes converted into alcohol and renders the cider limpid. 
The use of lead salt, formerly much in vogue in Normandy, 
is very dangerous. Persons drinking cider thus treated fre- 
quently feel sharp pains in the abdominal region, which pre- 
sent all the symptoms of lead colic and may even prove fatal. 

An admixture of lead salt is readily recognized. Add to 
the suspected cider solution of potassium iodide ; if lead salt 
be present, a yellow precipitate of iodide of lead will be 

Adulteration of Cider. According to most of the authorities 
on food, cider is but little subject to adulteration. Even Has- 
sall, who generally enumerates under each article of food a 
list of every conceivable adulteration that has ever been found 
or supposed to have been used in such food, only speaks of 
the addition of water, of burnt sugar as a coloring matter, and 
of the use of antacids for the correction of the acidity of spoiled 
cider. On the other hand, in France where, as previously 
mentioned, the consumption of cider is quite large, its adulter- 
ation is by no means uncommon. The following is considered 
in the Paris Municipal Laboratory as a minimum for the com- 
position of pure cider : 

Alcohol, per cent, by volume 3.00 

Extracts, in grammes per liter 18 00 

Ash . 1.7 


This is for a completely fermented cider. In sweet ciders 
the content of sugar should exceed the limit sufficiently to 
make up for the deficiency of alcohol, to which it should be 

In the samples of American ciders investigated by the 
United States Agricultural Department (see pp. 393-4), it was 
fully expected to find a number preserved with antiseptics. 
This supposition failed to be confirmed, however, for no sali- 
cylic acid was found, and in but one case was any test ob- 
tained for sulphites. None of the samples fell below the 
standard proposed by the French chemists, given above, and 
no metallic or other adulteration was discovered. 

There was, however, a single exception, No. 4927 in the 
table of analyses, p. 394, which was an embodiment in itself 
of nearly all the adulterations which have been enumerated 
as possible in cider. It was handsomely put up in neatly- 
capped bottles, and was of a clear, bright color. Its tremendous 
" head " of gas when uncorked gave rise at once to the sus- 
picion that it had received some addition to produce an 
artificial pressure of gas. The low content of free acid, 
together with the large amount of ash and a variable content 
of carbonic acid in different bottles, established the fact that 
bicarbonate of soda had been added, probably a varying 
quantity to each bottle, while the dose of sulphites added was 
so large that a bottle stood open in the laboratory all through 
the summer without souring. 

Manufacture of brandy from cider. Brandy is a mixture of 
water and alcohol produced by the distillation of a fermented 
liquor. It owes its aroma to the essential oil peculiar to the 
substance subjected to distillation. 

In Normandy the heavy ciders only are distilled, i. e., those 
containing the most alcohol. 

In years when there is an abundant crop of apples, it will 
generally be found of advantage to distil the cider made from 
fallen fruit and also from early apples. The cider yielded by 
them does not keep well, and brings a very low price, espe- 
cially when there is a large product from late apples. 


Sour ciders should not be distilled, they being better utilized 
for the manufacture of vinegar. Spoiled cider, as a rule, 
makes bad brandy. 

Different qualities of cider should be distilled separately. 
A skilled distiller can classify them by the taste, and separates 
them in order to obtain brandy of first and second qualities. 

The cider is distilled when it is completely fermented, i. e., 
when the largest possible quantity of sugar has been converted 
into alcohol. Cider from early apples generally ferments 
faster than that from late apples and can be distilled towards 
the end of December, i. e., from six weeks to two months after 
it has been made. Cider made from late apples, during 
December and January, is ready for distillation three or four 
months later, i. e., in March or April. 

Preparation of the juice for distillation. When there is an 
abundant crop of apples and barrels are scarce, the juice as it 
comes from the press is brought into large open vats in which 
fermentation progresses rapidly, but in this case some beer 
yeast previously mixed with a small quantity of cider is added 
to each vat and the temperature must be maintained between 
59 and 68 F. Under these conditions the juice ferments 
very promptly and may be distilled eight or ten days later. 

Sometimes the whole of the pulpy mass obtained by grind- 
ing the apples is submitted to distillation. In order to accel- 
erate fermentation a small quantity of hot water containing 
some sugar in solution is added to the mass, also one or two 
thousandths of sulphuric acid, the latter regulating the progress 
of fermentation. 

Fermentation being finished, the mass is subjected to distil- 
lation. In order to prevent this mass from adhering to the 
still and scorching, distillation must be conducted as slowly 
as possible and a small quantity of straw placed upon the 
bottom of the still, or, better, a piece of cloth to prevent direct 
contact of the mass with the heating surface. 

Plums, damsons, etc., are also subjected to distillation and 
produce good brandy. They ferment more slowly than wild 


cherries which produce the well-known cherry-bounce. Atten- 
tion may here be called to the distillation of wild plums, which 
should be gathered in the fall when the leaves begin to drop. 
Some connoisseurs consider brandy made from plums equal to 
that from cherries. On a farm, no fruit containing sugar should 
go to waste, as it can be converted either into brandy or vinegar. 

Distillation. For distilling cider on a small scale no ex- 
pensive apparatus is necessary, an ordinary still answering all 
requirements. Cider is distilled like wine. The still is filled 
about { full and after placing the head in position the joints 
are carefully luted by pasting strips of cloth or even paper over 
them. The tub holding the worm is tilled with cold water and 
the fire started. The vapors escaping from the boiling liquid 
condense in the worm and run into the receiver. Heating 
should be done slowly, in order to vaporize as little water as 
possible, and especially to avoid sudden ebullition, as the boil- 
ing liquid, getting into the head, would pass through the worm 
and become mixed with the liquor already distilled. In such 
an event it would be necessary to begin distillation anew. The 
operation is continued until the liquid produced contains 
hardly any alcohol, which can be ascertained by the use of the 
alcoholometer or by the taste. It is unnecessary to say that 
care must be had to constantly renew and keep cold the water 
in the tub holding the worm. 

Distillation being finished, the boiler is emptied, and after 
thorough cleansing is refilled for a second operation. 

The liquid produced by successive distillations is mixed 
together and brought into the still a second time, whereby a 
liquor richer in alcohol and of a better taste is produced. It 
would be desirable if this second distillation or rectification 
could be effected by means of steam. This would prevent the 
empyreumatic taste which is often noticed in apple-brandy. 
The first arid last runs of the still being of inferior quality are 
collected separately and poured back into the still when re- 
filling for the next operation. 

Calculations have been made to establish by means of figures 


the immense advantage offered in a financial point of view by 
the distillation of cider. These theoretical calculations, how- 
ever, are frequently very deceptive. If, on the one hand, the 
producer knows the content of alcohol of his cider and, on the 
other, the market value of the alcohol and of the cider, it will 
be easy for him to decide which product will pay him best. 

Pear-cider. The manufacture of pear-cider is very limited, 
and no great future can be promised for it, as even when most 
carefully prepared it is far inferior to apple-cider and other 
fruit-wines. Its preparation is best understood in England, 
and how little it is appreciated there is shown by the fact that 
three-fourths of the quantity manufactured is consumed by the 
farm-laborers. But any one who has large pear crops at his 
disposal and washes to use a portion of them for the manufac- 
ture of a beverage should add to the pear-must one-quarter its 
quantity of must of bitter-sweet apples or a few quarts of black 
currant juice, which will improve the taste of the cider and 
its keeping qualities. The mode of preparation is the same 
as for apple-cider, though still greater care must be exercised 
in the choice of the raw material. The pears must have a 
sufficient content of sugar, as otherwise the cider would not be 
sufficiently rich in alcohol and at the same time they must 
contain a bitter substance to prevent the cider from turning 
sour as soon as the conversion of the sugar is effected. Hence 
the use of fine table pears for the preparation of cider would 
be simply a waste of material. The only varieties suitable 
for the purpose are those which when eaten from the tree pro- 
duce a long-continued sharp heat in the throat and lie half a 
day undigested in the stomach, which, however, become sweet 
by long storing and lose enough of their acerbity to be no 
longer disagreeable to the palate. In England, the wild pear 
grown in hedges is generally used for the purpose. They 
must be ripe, but not soft or mellow. 

In the northern part of France pear-must is sometimes used 
for the preparation of " port wine," the taste of which is very 
much praised. The process consists in heating 50 Ibs. of must 


to between 176 and 185 F. and adding 5 pounds of raisins. 
At this degree of heat must and raisins are brought into a 
barrel which is tightly bunged and placed in a cool place. 
When in the course of a day the must is cooled to 59 or 68 
F., the raisins, which are generally put in a bag, are taken 
from the barrel and after bruising returned (but not inclosed 
in the bag) to the must, which is then allowed to ferment for 
14 days. The wine is then drawn off into stone jugs which 
are well corked and sealed. 

Quince Wine. A very spicy wine can be prepared from 
quinces in the following simple manner : Place the quinces 
for a few moments in hot water and then rub them with a 
cloth to remove the down. Next remove the cores by means 
of a knife or in any suitable manner. Now pour hot water 
over the quinces thus prepared and boil them slowly over a 
moderate fire until soft. Then press out the juice and add 
white sugar in the proportion of 1J Ibs. to every 20 Ibs. of 
fruits. Allow the whole to ferment in a cool room and from 
time to time add some sugar-water during the process. Clari- 
fication and racking off is effected in the same manner as with 



THE manner of obtaining the juice and appliances for that 
purpose have already been described in the previous chapter. 

a. From small fruits. One of the principal objections to 
wines from small fruits is that they easily turn. This can, 
however, be overcome by adding, after fermentation is finished, 
5.64 drachms of salicylic acid to every 100 quarts. By in- 
creasing the dose to 8.46 drachms less sugar can be added to 
the must, which, of course, makes the beverage poorer in alco- 
hol. A saving of sugar can be further effected without injury 


to the keeping quality of the wine by a suitable mixing of 
juices. By working, for instance, the juices of currant, or of 
raspberries by themselves, a considerable addition of sugar, 
about 1 pound per quart, has to be made, which can, however, 
be reduced one-half by mixing with a juice containing some 
bitter principle, and later on treating the wine with salicylic 
acid. Thus a large field for experimenting is opened to all, 
and only a few hints will here be given. Raspberry -juice 
should be mixed with one-quarter its volume of blackberry- 
juice ; and in the preparation of currant-wine it is especially 
recommended to use four-fifths of red to one-fifth of black cur- 
ants, the wine obtained being far more spicy and possessing 
better keeping qualities. Moreover, black currants used 
within limits are an excellent material for improving the 
flavor of almost all fruit-wines. The flavor and keeping qual- 
ities of fruit-wine are also improved by throwing a couple of 
handfuls of crushed hazel-nuts or walnuts into the barrel, and 
also by the addition of 2 ounces and 8 drachms of bitter al- 
monds, the peels of 10 lemons, 3 ounces and 5 drachms of 
cassia, and a few handfuls of bruised wild plums. By these 
means wine with a moderate content of alcohol acquires a 
strong taste, while its keeping quality is at the same time im- 
proved. The latter can also be effected by bringing 2 ounces 
and 3 drachms of tartar into the barrel during fermentation. 
A few other mixtures of juices may be mentioned. Blackberry- 
juice is better adapted to ferment by itself than any other juice 
from small fruits, but by the addition of J to J its weight or 
its volume of strawberry-juice the aroma of the wine is greatly 
improved. Strawberry -juice is least suitable for fermentation 
by itself, and should be mixed with must containing a bitter 
principle. The addition of J of the volume of the juice of the 
Siberian crab-apple (Pyrus baccata) can be highly recommen- 
ded for the purpose, it being especially suitable for improv- 
ing the keeping quality of fruit-wine. The juice of rhubarb 
stems may be added to that of elderberries, while the juice of 
gooseberries is suitable for mixing with that of mulberries. 


Moreover, a combination of several juices may also be used; an 
excellent wine being, for instance, prepared from equal parts of 
blackberry, raspberry, currant, and strawberry -juice, with an 
addition of walnuts as given above. In the receipts for the 
different varieties given below, the customary addition of sugar 
for unmixed fermentation and the omission of salicylic acid is 
retained, but it may be repeated that with the assistance of these 
means the cost may be reduced one-half. In order to avoid 
repetition, the following general rules are here given, which 
hold good not only for the preparation of wine from small 
fruits, but also from stone-fruits. 

The fruit to be used should be sound and ripe, though not 
over-ripe, and must be freed from adhering dirt by washing in 
warm water. Large quantities are best expressed by means of 
a press, while for small quantities a bag of coarse linen is suffi- 
cient, which is kneaded and squeezed until no more juice runs 
out. Over the residue pour as much hot water as juice is ob- 
tained, and after allowing it to stand for two hours press again 
and mix the juice obtained with the first. Now add sugar in 
the proportion of one pound to a quart of juice, and bring the 
whole into a thoroughly cleansed barrel previously rinsed out 
with salicylated water. Fermentation should take place in a 
room having a uniform temperature of from 59 to 64 F. 
During this process lay a piece of gauze upon the open bung- 
hole and secure it by means of a stone, piece of iron, etc., which 
prevents the access of foreign substances to the must. Every 
other day the barrel is filled up to the bung-hole with sugar- 
water prepared in the proportion of J Ib. of sugar to 1 quart 
of water. As soon as the "hissing" in the barrel ceases, bung 
the barrel tightly and after 14 days draw off the contents into 
another barrel placed in the same room. After 6 months the 
wine can be drawn off into bottles, being, however, 8 days pre- 
viously clarified with the whites of a dozen eggs or 1 oz. of 
isinglass slowly dissolved over a moderate fire in 1 pint of wine. 
Whatever fining is used, add it to the wine with constant stir- 
ring. If salicylic acid is to be used, it is best done in the man- 


ner described for cider when the wine has acquired the desired 
degree of ripeness. The bottles should be rinsed with salicyl- 
ated water and closed with corks previously soaked for a few 
hours in hot salicylated water. Sealing the bottles is not nec- 
essary, but in order to be sure that the corks fit closely, shake 
each bottle, with the neck downwards, with the right hand 
holding the left under the cork. If the slightest moisture is 
observed, the bottles must be recorked, as carelessness in this 
respect may cause a portion of the supply of wine to spoil. 
The corked bottles are laid in the cellar. 

This general method, according to which all kinds of wine 
from small fruits can be prepared, may be supplemented by 
the following receipts : 

Currant Wine. Among all varieties of berries the currant 
contains the largest quantity of free acid, about 2 per cent., 
and comparatively little sugar, about 6 per cent. The propor- 
tion between these two principal constituents is very unfavor- 
able for the manufacture of wine. The currant juice fer- 
mented by itself would yield a product which does not deserve 
that name. 

Free the thoroughly ripe currants from the stems and after 
crushing press out the juice. To the residue add twice or three 
times as much water as juice obtained and after again pressing 
add the juice obtained to the first. Now examine the juice 
as to its content of acid and if necessary dilute further with 
water. Then calculate the sugar in the manner previously 
given. Sugar and acid having been brought to the right 
proportion, the juice is allowed to ferment. 

Currant wine is frequently prepared as a sweet liqueur-wine, 
the following directions being much used for the purpose : 
Juice 100 parts, water 200, sugar 100. According to an an- 
alysis by Fresenius, the wine thus prepared showed after two 
years the following composition : 


Alcohol 10.01 

Free acid . 0.79 

Sugar 11.94 

Water 77.26 


According to another receipt, 17 J Ibs. of thoroughly ripe 
currants freed from the stems are bruised in a wooden vessel 
with the addition of 3J quarts of water. The paste thus ob- 
tained is gradually brought into a bag of coarse linen, which 
is laid upon an oblique board, and pressed out by means of a 
rolling-pin. The press-residues are returned to the wooden 
vessel and, after adding 7 quarts of water, thoroughly worked 
with a pestle, and then again pressed in the above manner. 
The juice thus obtained is brought into a barrel having a 
capacity of 34f quarts, a solution of 12 Ibs. of sugar in 14 
quarts of water is then added, and finally sufficient water to 
fill up the barrel to within 3 inches of the bung. After cover- 
ing the bung-hole with a piece of gauze, the whole is allowed 
to ferment in a room having a temperature of from 59 to 
64 F. When the principal fermentation is over, the barrel 
is entirely filled with water and closed with a cotton bung. 
The wine is then allowed to further ferment for six months in 
a cellar having a temperature of from 54 to 59 F., when it 
is drawn off into another barrel or into bottles. By adding to 
the fermenting juice J Ib. of comminuted raisin stems a pro- 
duct closely resembling Tokay-wine is obtained. 

A very strong beverage is obtained by adding to the expressed 
juice of currants twice the quantity of water and stirring in 2 
tablespoonfuls of yeast. Allow the juice to ferment for 2 days ; 
then strain it through a hair-sieve and after adding 1 Ib. of 
sugar for every quart, allow it to ferment. When fermenta- 
tion is nearly finished, add French brandy in the proportion 
of 1 quart to 40 quarts of the juice, and bung up the barrel 
two days later. The wine is ripe in four months. 

According to another receipt the currants separated from 


the stems, are pressed and the juice mixed with an equal quan- 
tity of water. Then add to each gallon of liquid 2J Ibs. of 
sugar, 2 ozs. of cream of tartar, and 1 oz. of pulverized nutmegs, 
with 1 quart of alcohol. Allow the whole to ferment, then 
fine with isinglass, draw off and bottle. 

Another method is to express all the juice possible, then take 
an equal amount of boiling water, and pour it on the expressed 
fruit. Let it stand for 2 hours, squeeze out as much as there 
is of juice and mix; then add 4 Ibs. of brown sugar to each 
gallon of Ihe mixture ; let it stand for 3 or 4 weeks, until fairly 
worked, with the bung out, and when it is done working, bung 
it up, then place it in a cool cellar. 

Strawberry-wine. For the preparation of wine very fragrant 
strawberries should be selected. The aroma of the strawberry 
is so delicate that it readily undergoes a change and soon dis- 
appears entirely. Hence to secure it and transfer it into the 
juice the strawberry requires special treatment, whereby neither 
the content of acid nor that of sugar is taken into considera- 
tion. This treatment consists in mixing the sound, ripe berries, 
without previous crushing or bruising, with the same weight of 
pulverized sugar and allowing the mixture to stand in a glass 
or stoneware vessel in a cool place until all the sugar is dis- 
solved to a clear syrup in which the shrunk and tasteless 
berries float. To separate the latter, strain the juice through 
a woolen cloth previously rinsed with some lemon-juice or 
tartaric acid, dilute with the same quantity of water, bring 
the acid to 0.5 per cent., and subject the whole to fermenta- 
tion in the usual manner at a temperature of from 50 to 
59 F. 

Some allow the berries to ferment with the juice, but the 
wine obtained is somewhat harsh and not as delicate. 

By finally adding to the finished wine from 4 to 5 per cent, 
of rock-candy, a liqueur-wine is obtained which, as regards 
aroma, cannot be surpassed, and is especially liked by ladies. 

Excellent strawberry wine is also obtained according to the 
following directions : Press out 10 Ibs. of different varieties of 


small and large cultivated strawberries, which give about 2J 
quarts of juice. Pour water over the residue and press again, 
so as to obtain about 3 quarts more of juice or a total of 5J 
quarts. Next dissolve 4 pounds of rock candy in 5 quarts of 
cold water, bring the solution, together with the 5J quarts of 
juice, into a small cask, and allow the whole to ferment in a 
cellar having a temperature of 61 F. In four weeks the wine 
is ready for drawing off into bottles. It is of a beautiful pale 
yellow color and possesses an excellent bouquet, and if made 
sparkling furnishes an excellent beverage. 

According to a receipt in the " Weinzeitung," 40 quarts of 
strawberries and 41 quarts of water, with an addition of 12 Ibs. 
of sugar, 3J ozs. of tartar, and a gallon of whiskey free from 
fusel .oil are allowed to ferment and the resulting wine i& 
treated in the usual manner. 

Another method is to pour 1 quart of hot water upon 1 
quart of crushed strawberries and pressing out after allowing 
the mass to stand for 2 days. Then add to every quart of 
juice 1 Ib. of sugar, and to every 40 quarts of juice the grated 
peel and juice of 2 lemons and 2 oranges and 4 quarts of 
French brandy. Allow the whole to ferment, and treat the 
resulting wine in the usual manner. 

Gooseberry-wine. The proportion between sugar and acid 
is somewhat more favorable in the gooseberry than in the- 
currant, but not sufficiently so as that the pure juice would 
yield a good wine by fermentation. Hence the juice must be 
converted into suitable must, as regards sugar and acid, in 
accordance with the rules previously given. The yellow varie- 
ties are preferable, they alone having a distinctly vinous taste ; 
the wine obtained from the red and green varieties being 
somewhat insipid. The juice is obtained in the same manner 
as from currants, the berries being bruised, the juice allowed 
to run off and the residue washed several times with water, so 
that each volume of juice receives an addition of 1 volume of 
water, though as the mixed juice has to be tested as to its- 
content of acid, the direction in regard to the addition of 


ivater need not be accurately followed. The must may contain 
-as much as 30 per cent., because the fermentation of goose- 
berry-must is generally carried on in the warmer season of 
the year, so that all or the greater portion of the sugar fer- 
ments and the wine, on account of the quantity of alcohol 
formed, will keep for an almost indefinite time. Gooseberry- 
wine made from must rich in sugar generall} 7 acquires by age 
an odor of Madeira-wine, which frequently deceives even con- 

Gooseberry-wine, like currant-wine being liked sweet, a 
larger quantity of sugar may be added to the must from the 
^tart, though for a quicker process of fermentation it is better 
io add the desired quantity of sugar to the fermented wine. 
If the must has been made quite sweet, so that a wine rich in 
alcohol is formed, no fear need be had of the wine fermenting 
anew on account of the addition of sugar. 

There are a number of receipts for the preparation of goose- 
berry-wine, but when more closely examined the products pre- 
pared according to them will be found either more or less rich 
in alcohol, or to contain more or less free acid, and to be either 
sweet or not sweet, so that- the proportion can evidently be 
-changed in any manner desired. It is further evident that 
nothing is gained thereby as regards quality, because the type 
for all artificial wines is grape wine obtained in a good season. 
In such wines the proportions between alcohol and free acid 
are well known and within such narrow limits that they cannot 
be essentially exceeded on either side, and they alone can serve 
as a basis for the rational preparation of gooseberry wine as 
well as of all artificial wines. With the aroma or bouquet which 
is to be imparted to such wine it is, of course, different ; but no 
special directions are required, as every one manages it accord- 
ing to his own taste or according to that of those who buy and 
drink the wine. Thus it is also with the addition of sugar ; one 
likes a sweet wine, the other one less sweet, and the third one 
without any sugar. The principal aim is to prepare a wine 
which contains the necessary quantity of alcohol to insure its 


keeping properly, and the power of resistance against decom- 
posing influences, and from which the greater portion of the 
fermentable substances is removed by fermentation. In most 
oases the natural conditions are of great use in this respect, 
for in order to decrease the content of free acid it becomes 
necessary to dilute the fruit juices, whereby the quantity of fer- 
mentable substances is also relatively decreased, and sometimes 
even to such an extent that they do not suffice for the complete 
fermentation of the sugar. Such wine, if not wanting in alco- 
hol, will keep for an almost indefinite time and may be ex- 
posed to the access of air and a high temperature without the 
appearance of the formation of acetic acid. 

Gooseberry Champagne. The taste of this beverage closely re- 
sembles that of genuine champagne. There are several modes 
of its production. In France a light wine which does not con- 
tain too many fermentable substances is used. Somewhat less 
than 2 per cent, of sugar, or about 15 grammes to a bottle of 
800 cubic centimeters' capacity, is dissolved in the wine and the 
latter drawn off into strong champagne bottles, which are then 
hermetically corked and tied with twine. The wine is then 
allowed to ferment in a room having a temperature of from 
77 to 99 F. When fermentation is finished, the bottles are 
brought into a cool cellar and placed first horizontally and 
then gradually bottom uppermost so that the yeast may collect 
on the cork and the wine become clear. When all the yeast 
is precipitated to the neck of the bottle, the sediment is care- 
fully removed degorgie as it is termed by first raising the 
string securing the cork and then the latter, the bottle being 
held in a horizontal position. The cork being no longer held 
by the string is forced out together with the deposit of yeast, 
while the clear wine impregnated with carbonic acid remains 
behind. To prevent the unavoidable loss of wine, the cork, 
together with the yeast and wine forced out, is collected in an 
upright barrel with a large aperture, towards which the mouth 
of the bottle is held during the operation. 

The wine thus impregnated with carbonic acid, however, is 


not yet champagne ; it only becoming so after the addition of 
a solution of fine rock-candy in brandy with which the bottle 
is filled up. Each bottle after receiving the necessary quantity 
of the solution, or liqueur as it is termed, is at once closed with 
a cork which is secured with twine or wire. Removing the 
deposit of yeast is the most difficult portion of this operation, 
long experience being required before the workman possesses 
the necessary skill. 

According to another method, which is also called the im- 
pregnating method, the sugar required for sweetening is dis- 
solved in the wine, and after clarifying the solution by filtering 
through paper pulp in a bag, or, if necessary, with some isin- 
glass, it is taken to the impregnating apparatus, one similar to 
that used for mineral water answering the purpose. The wine 
is then saturated under a pressure of 4J to 5 atmospheres with 
the desired quantity of carbonic acid and at once drawn off 
into bottles, which are corked and wired as above. 

The advantage of this last named method consists in the 
rapidity with which champagne can be made, 30 to 36 months 
being required for the first method before the champagne is 
ready for transportation. 

The following method is the most simple of all, but does 
not yield as fine a product. Each bottle is finished by itself 
and no special apparatus is required. The wine is sweetened 
and clarified in the same manner as in the impregnating 
method and then drawn off into bottles. In case the wine is 
not rich enough in alcohol, the content of the latter may be 
increased by 10 per cent. 

After having filled the bottles about 1.52 cubic inches less 
than generally, add first to each bottle 11 drachms of pure 
crystallized bicarbonate of potash and immediately afterwards 
1 oz. of pure crystallized tartaric acid in pieces. Then close 
the bottle with the cork and secure the latter by tying or wir- 
ing it crosswise. The potash and acid are now brought to 
solution by gently swinging the bottle to and fro, the contents 
becoming at the same time turbid by the separation of bitar- 


trate of potash. By placing the bottle bottom upwards, the 
separated tartar is collected as much as possible upon the 
lower surface of the cork, and after the wine is clear, removed 
in the same manner as described in the first method. It is 
not absolutely necessary to remove all the tartar, as it settles 
on the bottom and the champagne will pour out clear. 

According to any of these methods all fruit wines can be 
converted into champagne or sparkling wines. 

Semler gives the following directions for the preparation of 
gooseberry champagne. Pour 20 quarts of warm water over 
20 quarts of crushed gooseberries and add 6 Ibs. of sugar, 4| 
Ibs. of honey, 1 oz. of pulverized tartar, J oz. of dried lemon 
peel, and f oz. of dried orange peel. After standing for two 
days strain the mixture through a hair-sieve into a barrel and 
add 2 quarts of French brandy. When the " hissing " in the 
barrel ceases, clarify the wine and after a few days draw it off 
into bottles, securing the corks with wire. Before filling the 
bottles throw a piece of sugar and J drachm of bicarbonate of 
soda into each. 

Raspberry Wine. Raspberries have such an agreeable and 
refreshing taste and odor that, while they are not very sweet 
and the proportion of acid to sugar is not very favorable, they 
are great favorites. Their aroma passes into the wine and 
would be even too predominant if for the preparation of wine 
the juice had not to be strongly diluted with water in order to 
decrease the acid. 

As in all other fruit, the quality of the raspberry depends on 
the weather, and when this is favorable during the time of the 
development and maturing of the fruit, the latter is sweet and 
palatable, but in cold and wet seasons, sour and harsh. No 
other fruit suffers as much from such conditions as the rasp- 

We have the wild and -cultivated raspberry. The wild rasp- 
berry is smaller than the cultivated but possesses a stronger 
aroma, but unfortunately is too frequently infested with the 
larva of many insects to render it always palatable. The cul- 


tivated raspberry is considerably larger, and is less attacked 
by worms, but possesses less aroma and is frequently even 

To obtain the juice for the preparation of wine the thoroughly 
ripe raspberries are crushed to a paste in a wooden tub by 
means of a wooden pestle. To separate the grains, the paste is 
forced through a fine wire sieve, which, in order to protect it 
from the acid is best provided with a coat of asphalt or shellac 
varnish. It is, however, no disadvantage to allow the grains 
to ferment with the pulp, some tannin being thereby intro- 
duced into the wine, which under certain circumstances may 
be even desirable. 

The content of acid in the raspberry varying considerably in 
different years, a test of the juice in this respect becomes abso- 
lutely necessary in order to enable one to dilute it in. the cor- 
rect proportion with water. For this purpose press out a small 
quantity of the crushed raspberries and determine the acid in 
the manner previously given. The sugar contained in the rasp- 
berry need not be taken into consideration, since by dilution it 
is reduced to 1 per cent, and still less. The must is simply 
brought up to 25 per cent, of fruit-sugar and allowed to fer- 
ment in the usual manner. The treatment of the wine after 
fermentation is the same as for other fruit wanes. 

Blackberry wine is prepared in the same manner as raspberry 
wine. Of the numerous directions for its preparation we give 
the following : Gather the berries on a dry day, crush them 
with the hand into a kettle, and add just enough hot water to 
cover the mass. Then add a handful of bruised raisins and a 
handful of strawberry leaves, from the heart of the mother 
plant, or, still better, from the suckers, and allow the mass to 
stand for four days, when a crust of yeast will have formed on 
the surface. The mass is now pressed out and sugar in the 
proportion of 1 pound to every 4 quarts added. Fermentation 
is allowed to go on for two weeks, when the barrel is bunged 
up and* the wine drawn off after six months. During fermen- 
tation, and especially in the beginning of it, care must be had 
to fill up the barrel. 


To make from blackberries a beverage resembling port-wine 
the following method is recommended : Press out the juice and 
allow it to stand for 36 hours. While fermenting during this 
time remove all scum from the surface. Now add of water, 
one-fourth the quantity of juice, and 3 pounds of brown sugar 
to every 4 quarts of fluid and filter after 32 hours. Fermen- 
tation, which requires but a few days, being finished, bung up 
the barrel tightly and after six months draw off the wine. 
The latter improves by age. 

Mulberry Wine. Press the juice from the fruit, dilute with 
the same quantity of water, add 1 pound of sugar for every 
quart of liquid, and boil the whole j- hour. Then add for 
every 100 quarts, 3 quarts of alcohol, 6J ounces of tartar, 1 
ounce of cassia, and J ounce of bruised bitter almonds, and 
allow the whole to ferment. The further treatment of the 
wine is the same as for other fruit-wines. 

Elderberry Wine. Boil equal quantities of berries and water 
one-half hour, pour the whole into a hair-sieve, press the pulpy 
portion of the berries gently through with the hand and re- 
move the residue. Compound the strained juice with sugar 
in the proportion of { pound to 1 quart, and boil 20 minutes. 
As soon as cool bring it into a barrel to ferment. Fermenta- 
tion being finished, paste stiff brown paper over the bung- 
hole, and after eight weeks draw off the wine in bottles. 

Another method is to boil 50 quarts of water, 10 quarts of 
elderberries, 40 pounds of sugar, 5 ounces of pulverized ginger^ 
and 2J ounces of cloves for 1 hour, with constant skimming. 
Then bring the liquid together with 4 pounds of crushed rai- 
sins into a barrel and allow it to ferment. At the termination 
of the fermentation it will yield a wine similar to the Cyprus^ 
or Greek-wine. 

Juniperberry Wine. 70 quarts of water, 35 pounds of crushed 
raisins, 10 quarts of juniperberries, 4 ounces of tartar, 1 quart 
of French brandy, and a handful of fresh marjoram leaves 
are brought into a barrel and the mixture is allowed to fer- 
ment for 12 hours. 


Rhubarb Wine. Add to every 5 pounds of the thinly-sliced 
stalks 2 \ quarts of soft water and bring the whole into a clean 
wooden vessel. Cover the latter and stir the contents with a 
wooden stick three times daily for one week. Then pass the 
fluid through a wide-meshed sieve and add to every 3 quarts, 
4 pounds of white sugar, the juice of 2 lemons, and the peel 
of 1 lemon rubbed upon sugar. Allow the mixture to ferment 
in a barrel, and after clarifying, draw the wine off into bottles 
in March. 

The variety of rhubarb known as Victoria is best adapted 
for the preparation of wine, which can also be effected accor- 
ding to the following directions : Cut up the stalks and express 
the juice. To every gallon of juice add 1 gallon of soft water 
and 7 pounds of brown sugar. Bring the mixture into a bar- 
rel and allow it to ferment until clear, with the bung out, keep- 
ing the barrel filled with sweetened water as it works over ; 
then bung the barrel tightly or draw the wine off into bottles. 
It makes an agreeable and healthful wine affording a good 
profit, as nearly 1800 gallons of wine may be obtained from 
each acre of well-cultivated plants. The stalks will furnish 
about three-fourths their weight in juice. 

Tomato Wine. Press out the juice from ripe tomatoes, add 
to each quart of it 1 pound of brown sugar, and allow the 
whole to ferment. After three months the wine can be drawn 
off into bottles. 

Parsnip Wine. Cut 12 pounds of parsnips into thin pieces, 
add 15 quarts of water and boil until soft. Then press out 
the juice and after straining through a hair-sieve sweeten with 
j pound of sugar per quart. After again boiling for j hour it 
is brought, when cold, into a barrel and a tablespoonful of 
yeast is added. Stir the juice daily for 10 days, then bung up 
the barrel tightly and after six months draw off the wine into 

In the same manner wine may be prepared from carrots, 
clover heads, corn stalks, etc. It is, however, recommended 
to add to the juice some aromatic substance such as a handful 


of marjoram, almonds, plum kernels, currants, walnuts, ginger, 
or still better a few quarts of black currant juice. 

b. From Stone Fruits. Cherry Wine. Stone sweet cherries 
and after crushing the pulp to a paste allow it to ferment in 
stoneware pots for 12 hours. Then press out the juice, which 
is returned to the pots and allowed to stand until yeast fungi 
rise to the surface. Now add 1 pound of sugar to every 3 
quarts of must, bring the latter into a barrel and allow it to 
ferment 8 days. Then rack the wine into bottles and keep in 
a cool place. The preceding is the method followed in Eng- 
land where pure cherry wine is made. It may, however, be 
remarked that it is somewhat insipid. A mixture of the juice 
of cherries with that of the raspberry or currant can, however, 
be highly recommended, it yielding a beverage similar to port 
wine. It is an American receipt and much preferable to the 
English. Press the freshly gathered cherries, black or red, 
but selecting those with the softest pulp, without crushing the 
stones. To the juice obtained add one-eighth of its quantity 
each of raspberry and black currant juice, and sweeten with 
lump sugar in the proportion of 1 pound to 2J quarts of juice. 
The whole is then brought into a barrel to ferment. When 
fermentation is finished close the barrel tight and allow it to 
rest for three months. Then clarify the wine and draw it off 
into bottles. It is fit to drink in six weeks. 

Morello Wine. Press 60 pounds of morellos so as to crush 
the stones, mix the juice obtained with 20 quarts of sherry 
wine and the same quantity of warm water, and bring the 
whole into a barrel to ferment. Suspend in the barrel a bag 
containing 1J ounces each of cinnamon, powdered nutmeg 
and mace, allowing it to remain until drawing off the wine. 
The latter is very palatable in two months after fermentation 
is finished. 

Plum Wine. Not all varieties of plums are suitable for the 

preparation of wine, but the Heine Claude and Mirabelle can 

be highly recommended, the latter especially making as spicy 

and agreeable wine as any variety of fruit. With the almost 



innumerable varieties of plums it is not possible to say which 
are suitable for the preparation of wine and which are not. It 
can only be determined by experiment, though right sweet 
varieties only should be chosen. In this country the small 
sweet variety known as the wheat plum, etc., is frequently 
used for the purpose. The process is as follows : Stone the 
plums, then bruise the pulp, and add to every 8 pounds of the 
latter 3 quarts of hot water. After 2 days press out the juice 
and add to every two quarts of it one pound of sugar. Now 
bring the juice into a barrel in a cool room and add the 
crushed kernels of -f- of the stones. Allow the whole to fer- 
ment completely. After 12 months the wine is clarified and 
drawn off into bottles, each of which receives a small piece of 
sugar, which improves the keeping qualities of .the wine. 

Apricot and Peach Wines. Both these varieties of fruit are 
used when nearly ripe. Remove the stones and crush the pulp 
to a paste. For every 8 pounds of the latter add 1 quart of 
fresh soft water, and let the mass stand 24 hours. Then 
press out the juice, add for every 2 quarts of it 1 pound of 
sugar, and allow it to ferment. During fermentation it is rec- 
ommended to throw a handful of the crushed stones into the 
barrel, which gives to the product a more spicy flavor. 

Sloe or Wild Plum Wine. This beverage is not to be de- 
spised if prepared in the manner given for plum wine. The 
sloes must, however, remain on the bushes until after the first 
frost, which sweetens them. 





THE use of hermetically closed tin cans for preserving fruit 
has become of great commercial importance. Before discuss- 
ing it, the various ways which have proved more or less satis- 
factory for household purposes will be briefly mentioned. 
The following rules apply, however, to all methods : 

1. The fruit must be gathered in dry weather and when free 
from dew. It is to be kept as free from dust as possible. 

2. Absolutely sound fruit, not over-ripe, should only be se- 

3. The fruit should be preserved immediately after gather- 

4. The utensils used must be kept scrupulously clean. 

5. The preserving vessels should not be placed directly 
upon the fire. 

6. A good quality of white sugar only should be used ; 
brown sugar injuring the taste and color of the fruit. 

7. Copper or enameled pans alone should be used for boil- 



ing, if the latter is not effected in glass. The spoons should 
be of wood or of bone. 

8. The jars or cans should be thoroughly rinsed, best with 
salicylated water, and if corks are to be used they should be 
perfectly sound and scalded in hot water to which some sali- 
cylic acid has been added. 

9. Small jars or cans are preferable to large ones, and they 
should be kept in a dark, cool, dry place. 

Bottled fruits should always be sterilized for 10 minutes, 
from the time the boiling-point is reached, in the case of 
J-bottles, 12 minutes for J-bottles, and 15 minutes for full- 
sized bottles. Only in the case of halved apricots and peaches 
and similar fruits that lie closely together, should a few 
minutes extra be allowed. Fruits that change color when 
heated, for instance, white .pears, peaches and gooseberries 
should be separated after sterilizing in order to accelerate 

First may be mentioned the old French method, known as 
au Baine-Marie, which on account of its simplicity, is still 
much used. Berries require no preparation, but peaches, 
apricots and plums must be stoned and halved, and cherries 
and small plums stoned. Apples arid pears are peeled and 
quartered and immediately thrown into boiling water for 4 
minutes to bleach, They are then laid a few minutes upon a 
sieve to dry, and brought, like other fruit, by means of a spoon 
into wide-necked glass jars which are rilled to within 2 inches 
of the edge. In placing the fruit in the jar press it well to- 
gether. The empty space is then filled up with hot syrup 
composed of 2 parts of sugar and 1 part of water, and the jars, 
after heating them somewhat upon a stove, are placed in boil- 
ing water for 8 minutes for kernel fruit and for 10 minutes for 
stone-fruit or berries. The jars are then immediately corked 
and sealed. 

According to another French method, the flesh of the fruit 
is preserved without boiling. Stone-fruits and berries only 
can be used. The fruit is pressed through a, hair-sieve and 


the pulp mixed with an equal weight of pulverized sugar. 
The mixture is then brought into glass bottles, which are 
corked and sealed. This fruit-pulp keeps, however, only 
through the winter, or if kept in a cold place or in a refrig- 

The following method gives better satisfaction : The fruit, 
such as cherries, berries, plums, peaches, apricots, etc., is, 
without the addition of water, brought into wide-necked glass 
jars in such a manner that a layer of fruit alternates with 
a layer of sugar, the top layer being sugar. The jars are then 
tied up with salicylated parchment paper, placed in a water- 
bath, and the water kept boiling for 15 to 30 minutes, accord- 
ing to the variety of fruit, small fruit requiring less time than 
large, and berries only about 1G minutes. The jars are then 
stored in a cool, dark place. For closing jars with narrow 
mouths corks are preferable. They are soaked in hot salicy- 
lated water and sealed. 

Fruit thus preserved retains its fresh, natural appearance 
and keeps for a considerable time. If appearance is, however, 
of secondary consideration, it is better to boil the fruit, as is 
done with kernel fruit, melons, and all large varieties. The 
preparation for this method varies according to the nature of 
the fruit. Apples and pears must be peeled, and, if not too 
large, only cored, otherwise they have to be halved or quar- 
tered. Melons are peeled and cut into strips. Quinces are 
steamed until soft, then peeled as clean as possible, quartered, 
and the cores removed. After this preparation the fruit is 
brought into the preserving kettle and as much water as is 
necessary for boiling added. Boiling should be done very 
slowly and continued until the fruit commences to get soft. 
It should not be boiled too soft, but only sufficiently so to 
enable it to absorb the sugar-liquor. When this is the case 
the fruit is taken from the fire and strained, and with the liquor 
a syrup of the following composition is prepared : For each 
pound of fruit take one pound of sugar and soak it in J pint 
of the liquor. It is then placed upon the fire and the resulting 


syrup skimmed. When it boils the fruit is introduced and 
slowly boiled, or rather simmered, because it must not fall to 
pieces, for five to ten minutes, according to its softer or harder 
nature. The fruit while still warm is then brought into the 
jars, in which no vacuum must remain. Hence they must be 
filled up to the cork, or if bladder or parchment paper is used, 
for closing them up to the rim. In the latter case it is advis- 
able to place upon the surface a close-fitting piece of paper, 
previously saturated with a concentrated solution of salicylic 
acid in rum. Currants, blackberries and grapes are sometimes 
preserved in their natural clusters. They are first washed in 
fresh water, then slowly boiled soft, and strained. With the 
liquor a syrup of the previously mentioned composition is 
prepared, which is boiled and skimmed and poured upon the 
fruit in the jars. 

Fine table pears are sometimes preserved in the following 
manner : Eight large pears are placed in a syrup prepared 
from 6 ounces of sugar, 3 ounces each of cloves and allspice, 
J pint of water, and J pint of port wine or other sweet red 
wine. In this syrup they are boiled very slowly as much as 
3 hours until soft, and, while still warm, are brought to- 
gether with the syrup into jars, which are treated in the 
manner previously described. By taking equal parts of pears 
and of fine plums a very beautiful product is obtained. 

The boiling down of fruit in large stoneware pots is fre- 
quently accompanied by mishaps, and is more and more super- 
seded by other methods. It consists in dissolving J to f pound 
of sugar in water and boiling the resulting syrup together with 
the fruit until the whole forms a jelly-like mass. While still 
warm the pots, which must be full, are tied up with bladder. 
A piece of salicylated paper should be placed upon the surface 
of the fruit before tying up the pots. 

Preserving in Air-Tight Cans. This method, as previously 
mentioned, has become of great commercial importance. The 
number of factories, briefly termed canneries, has largely in- 
creased, and not a few of them employ 1,000 hands during the 


fall. Of course these factories do not limit themselves to the 
canning of fruit, as otherwise they would have to cease opera- 
tions during the winter months, but that branch of the busi- 
ness preponderates over all others. The search after other 
suitable material is constantly more extended, and the trade- 
list of a large English factory now contains 200 different 
articles ; including all Southern fruits, a portion of which 
is, singularly enough, returned in this state to the tropics. 
The American trade-lists embrace, as a rule, three groups, viz : 

1. Apples, pears, peaches, apricots, plums, strawberries, 
raspberries, blackberries, currants, cranberries, whortleberries, 
nectarines, grapes, cherries, quinces, cocoanuts, pineapples, 
marmalade, jelly, green walnuts. 

2. Peas, beans, beans with pork, corn, tomatoes, asparagus, 
carrots, onions, pickles, cauliflower, horseradish, mushrooms, 
catchups, succotash, plum-pudding, sweet potatoes. 

3. All kinds of poultry, venison, salmon, lobster, crawfish, 
oysters, crabs, beef, mutton, pork, eels, salt-water fish, ham, 
pig's feet, beef tongue, lamb's tongue, frog legs, mussels, etc. 

All the varieties of fruit named in the first group being not 
-equally well adapted for canning, the less suitable kinds are 
only used in small quantities. Plums and cherries are pre- 
ferably stoned, as well as peaches and apricots. Heart-cherries, 
black raspberries and whortleberries are the best suitable 
varieties of fruit for canning, as they loose their agreeable 
taste by steaming. Strawberries also become somewhat insip- 
id, but red raspberries are excellent provided they are canned 
as soon as possible after being gathered. Blackberries are not 
quite so good though if, brought into the can immediately 
when plucked, they furnish an agreeable dish. Currants 
have too many seeds, and are better used for jelly. Black 
currants are well suited for canning, and in this state are 
much used by bakers for tarts. Gooseberries canned before 
entirely ripe are very good. Among the smaller stone fruit 
the Mazard cherry has few superiors, as if carefully canned it 
retains its shape, color, and aroma as on the tree. Most plums 


are suitable for canning, provided they are stoned. Among 
the kernel fruits the quince occupies the first rank, as it is the 
only variety of fruit which gains by steaming. Pears are very 
suitable for canning, and even the inferior qualities can be 
used for the purpose. Apples, however, must be carefully 
selected, and only sweet varieties with firm flesh should be 
used. The Siberian crabapple can be highly recommended 
for the purpose. 

As a general rule fruit for canning should have a firm flesh 
and fine aroma, these conditions being found in all the vari- 
eties preferred by the packers in the United States, whose 
canned goods can be found in every large city of the world. 

Next to the variety of fruit, the cans are of the greatest im- 
portance. Much has been said and written in regard to them, 
and the discussion pro and con will very likely be continued. 
Glass jars have some advantages. They are comparatively 
cheap, allow of an inspection of their contents and the ready 
recognition of a leak, and are not attacked by the vegetable 
acid. But, nevertheless, they have not been introduced into 
general use because they are liable to break, and, being heavy, 
increase the cost of transportation, and, finally, it is difficult to 
close them air-tight. The sealing of a bottle with a narrow 
mouth is quite a different thing from sealing one with an aper- 
ture three inches in diameter. It may do for pickles, marmalade 
or jelly, but for preserved fruits which are to be transported 
long distances it cannot be depended on. The same objections 
may be made to stoneware jars, which possess the further dis- 
advantage .that their contents cannot be inspected and a leak is 
difficult to discover. Nevertheless, they are used by some large 
English factories for the reason, it is claimed, of keeping their 
products free from influences deleterious to health. To facili- 
tate sealing, the jars are generally small of about one pound 
capacity. Tin cans have many defects, but their use is very 
extensive, and in the United States they are almost exclusively 
employed. Complaint has been frequently made that the use of 
tin cans is deleterious to health because the tin contains lead, 


which is dissolved by the vegetable acid and transferred to the 
fruit-s} T rup. In reply it has been said that only the inferior 
qualities of tin contain lead, and that only in an infinitesimal 
quantity ; but it cannot be denied that the solder may readily 
become injurious to health and in cases of poison investigated 
in the United States and England it could in every case be 
shown that the respective cans were soldered on the inside. 
The time is very likely not very distant when such soldering 
will be entirely done away with. To completely overcome all 
complaints against solder, as well as against a content of lead 
in the tin, cans are manufactured which are provided inside 
with a thin coating whereby the contents are protected from 
contact with the metal. The insoluble constituent of this 
coating consists of silicate of lirne or glass-powder previously 
treated with hydrofluoric acid, while the soluble constituent is 
silicate of soda or of potash. Any silicate of earthy bases or 
metals may be used, or a precipitated gelatinous silicate. The 
alkali is fixed or removed by means of a bath containing a 
dilute solution of hydrofluosilicic acid, or a dilute solution with 
any other suitable acid. For preparing the composition mix 
the soluble with the insoluble silicate. The tin plates are 
coated with this mixture by means of a brush, or dipped in a 
bath of it and then dried by heat. The plates thus acquire a 
glass-like coating, which remains fixed no matter how the 
plates may be handled and worked.* 

In the canneries in the United States the cans are manufac- 
tured in a special department, and the division of labor is 
carried so far that every can passes through eight hands before 
it is finished ; and only with such a system is it possible to turn 
out large quantities in an incredibly short time. This far- 
reaching division of labor is, however, not limited to this 
department alone, but is the supreme law in the entire estab- 
lishment. In the same department the solder is cut by a 

* In this country some packers of lobsters, shrimps, etc., line the cans with 
parchment paper. 


machine into small three-cornered pieces. Each workman 
receives a certain quantity by weight of solder and of char- 
coal, with which he is expected to solder a certain number of 
-cans. The workmen are paid by the piece, and each solderer 
has a number which is stamped in every can he solders, so 
that those which prove leaky may be returned to him for re- 
pair. By this system there is no waste of material, and the 
leaky cans do not exceed 5 in 1,000. 

In another department the fruit is carefully inspected on long 
tables ; the unsound being thrown out, and the sound turned 
over to the peelers and stoners, who of course work with the 
most improved machines. There are carriers bringing un- 
interruptedly fresh fruit, and off-bearers removing and sorting 
the waste. Nothing is thrown away, the waste being used 
partially in the manufacture of jelly and partially in distilling, 
-and even the stones are utilized, as they are sold either to 
nurserymen or to chemical factories. Other workmen are 
occupied in placing the peeled and stoned fruit in the cans, 
which are handed over to boys, who place them upon small 
trucks running upon rails and transport them to the depart- 
ment where the filling in takes place. In the same department 
the syrup of sugar and water is prepared, but if the propor- 
tion of composition were asked a different answer would be 
received in every cannery. In regard to this point every 
manufacturer has his own ideas, which also extend to modifi- 
cations for the different varieties of fruit. All manufacturers 
agree, however, that the best quality of white sugar should be 
used for light-colored fruits, and light-brown sugar for dark- 
colored, and that the syrup must be perfectly clear, and hence 
very carefully skimmed in boiling. In most factories the 
syrup used consists of 1 Ib. of sugar dissolved in 1 pint of 
water. The filling of the cans with the fruit and syrup, the 
latter being generally kept warm, is effected with the assist- 
ance of scales, so that each can has exactly the weight upon 
which the selling price is. based. The caps, previously pro- 
vided with a hole the size of a small pea, are then soldered 


upon the cans. The hole in the cap serves for the escape of 
the air during, the succeeding process. 

Different kinds of apparatus are used for the expulsion of 
the air by heating the cans. In large factories a steam retort 
is used which resembles in shape a ship's steam boiler. It is 
provided with a door closing air-tight, and is divided in the 
center so that it can be filled either half or entirely with steam, 
as may be required. The cans to the number of from 400 to 
600 are placed upon trucks which run upon rails leading into 
the retort. Eight such trucks can be introduced at one time, 
so that is is possible to steam from 30,000 to 40,000 cans per 
day. The retort being filled, the door is closed and the pipe 
communicating with the steam boiler opened. The cans re- 
main in the retort from 15 to 30 minutes, according to the 
variety of the fruit : Berries 15 minutes, stone-fruits 20, apples 
and pears 25, quinces and tomatoes 30. The door is then 
opened, and after the steam has somewhat dispersed the trucks 
are quickly pushed to the tin-shop, where the cap holes are 
soldered up. To cleanse the cans and make them shiny they 
are next put, in a bath of soda water and then rinsed off with 
cold fresh water. They are then transferred to the store room, 
where they remain standing quietly for one week, when they 
are tested by striking the cap of each a short sharp blow with 
a wooden hammer. If everything is in order, the cap sinks 
slowly down, but if it is elastic and jumps back the can is 
what is called a "swellhead," and is returned to the tin-shop 
for repairs and is then again steamed. The perfect cans are 
labeled and packed and are now ready for market. 

Another apparatus which can be highly recommended for 
small factories consists of a round iron plate resting upon a 
brick base about one foot high. Two round iron rods run up 
opposite to each other from the edge of this plate and serve 
as a support for a movable iron cylinder open at the bottom 
and closed on top. Upon the iron plate the cans are placed in 
the form of a pyramid, and the cylinder is then drawn down 
and screwed air-tight to the plate. A pipe communicating 


with the steam-boiler enters the cylinder, and as soon as the 
latter is connected with the plate steam is admitted. After a 
certain time, which corresponds with that previously given, 
the steam is shut off, the cylinder pushed up, and the cans re- 
moved, the further treatment of which is the same as given 

In some factories the cans are still heated, according to the 
old method, in boiling water. For this purpose the cans 
100 at a time are placed upon an iron plate attached to a 
steam-crane and submerged for 15 to 20 minutes in boiling 
water in a large shallow kettle. In this case the caps, are not 
perforated, but soldered down air-tight. A workman watches 
the cans while they remain in the water and by means of a 
tool removes those from which small bubbles arise. Such cans 
being not air-tight are returned to the tin-shop for repairs. 

The rest after being heated are also brought to the tin-shop, 
where the caps are perforated with a hole the size of a small 
pea, which is again soldered up after the escape of the heated 

The canning of tomatoes, asparagus and other vegetables 
is effected in a similar manner except that no syrup is used. 
The Appert process for canning meat described later on under 
"Preservation of Meat, Fish and Eggs" is frequently used for 
the more expensive kinds of vegetables, such as asparagus, 
green peas, etc., glass vessels being generally used. The vege- 
tables are first cleaned and trimmed, and are then covered 
with water in the vessels, with or without a little salt. Sticks 
of asparagus, or whole beans, are stood on end. The vessels 
are now lightly corked and boiled in a bath of concentrated 
brine, in which they are stood upright as fully immersed as 
possible. The bath is heated very slowly to avoid cracking 
the glass. It should take about two hours to bring the tem- 
perature to 212 F. The brine is then brought to the boil, 
whereupon the contents of the glasses will also boil. After 
they have been boiled for about ten minutes, the bath is al- 
lowed to cool to about 140 F., and the corks are driven in 


tightly. Fused paraffin is then poured over them, and when 
the bath is quite cold, the glasses are taken out. The vege- 
tables will then keep for as long as the vessels are unopened, 
for all ferments in them have been destroyed, and the para- 
fined cork prevents any more from getting access to them. 
The paraffin should come flush with the edge of the jar, and 
should be tied over with vegetable parchment to prevent it 
from cracking and flaking off. The top of the cork should be 
rough so that it may adhere better to the paraffin. 

As the canning of tomatoes may serve as a type for all other 
vegetables a description of the process, for which we are in- 
debted to Mr. Richard T. Starr, of Salem, N. J. is here given. 

The tomato was for many years found only in hot-houses 
and conservatories of the rich. It was known as the love- 
apple and considered a curiosity. Our ancestors had no idea 
that this small red berry, for such was about its size, would 
ever, even under careful cultivation, become of mammoth 
size and form one of our most important articles of food. But 
such is actually the case to-day. The exact time when the 
now great industry of canning this vegetable commenced can- 
not be established with any certainty. The taste for the 
tomato seems to be an acquired one, and for years the industry 
struggled in its infancy until the breaking-out of the War of 
the Rebellion caused a demand that rapidly grew into gigantic 
proportions, and to-day finds the tomato-canning industry 
employing an army of men, women and children, while 
millions of dollars are invested in the payment of labor and 
the erection of plants. 

In order that our readers may have a clear idea of the busi- 
ness we will commence with the beginning. Having made up 
his mind to engage in it on an average scale, the packer will 
first find a suitable plot of ground, on a navigable stream, 
if possible. Having secured this, the next thing is the erec- 
tion of the buildings ; these are generally one story in height 
and as large and roomy as the capital will warrant. The 
next step is to secure the requisite supply of fruit, and for 


this purpose the farmers are drawn on and contracts entered 
into with them in which the packer agrees to take the entire 
marketable product of a certain number of acres, or else to take 
so many tons. These contracts are generally made about the 
first of the year, and as soon as the sun drives the frost from 
the ground the farmer prepares his beds and sows his seed. 
While the latter is growing, the land which is to be planted is 
heavily manured and plowed and carefully worked until it be- 
comes mellow, and then hills about four feet apart are made, 
and into each one is put a small quantity of compost of phos- 
phates. The tomato plants, having by this time grown to the 
height of 6 or 8 inches, are taken from the beds, and on a 
cloudy day, or the latter part of a bright day, transplanted 
and tended about as other growing crops. With a favorable 
season the farmer should commence delivering to the factory 
about the middle of August. 

The arrangement of a canning factory is, of course, a matter 
of taste, but the most complete, in our opinion, is one where 
everything moves in a straight line, and in which none of the 
help are obliged to interfere with one another. The first thing 
to be done with a load of tomatoes is, of course, to weigh 
them, and for this purpose platform scales are built at an end 
door and the wagons driven on them. After being weighed 
the tomatoes are handed over to the scalder. Tomatoes arriv- 
ing in all kinds of weather and conditions must, of course, not 
only be washed but scalded, so as to thoroughly loosen the skin 
from the pulp; and to do this quickly and properly, a heavy 
box of white pine is fitted with both steam and water pipes, and 
attached to it is an iron cradle swinging on hinges and raised 
and lowered by a wheel and pulley suspended above. On the 
back of this is placed a box, and as the farmer hands off his 
baskets they are emptied into this box, and at the command 
of the man at the rope, who is called the " scalder," they are 
dumped into the boiling water beneath. A few seconds suffice 
to clean and scald them ; the cradle is then raised and the 
tomatoes are poured into kettles set in front of the scalder to 
receive them. 


While this has been going on a group of women and girls 
have been filing into the factory and seating themselves along 
the trays that are to receive the tomatoes from the scalder. 
These trays are of different construction, but are similar as re- 
gards length, breadth and depth, the only difference being in, 
the various ways of getting rid of the water and juice. This- 
is generally done by making a slat frame fit in the bottom and> 
over a trough fastened under the tray. This leads to a drain, 
which carries it to the creek or wherever else it is to go. At 
each tray are from ten to twelve women, each of them furnished 
by the packer with a bowl and knife, and provided at their own 
expense with a neat water-proof apron. The tomatoes are- 
dumped from the kettles in front of them, and they remove 
rapidly the already loosened skins and cores and deposit the 
prepared fruit in a bucket sitting beside them. They become 
so efficient that a smart, active woman will frequently skin from, 
40 to 60 buckets a day, and as they receive 4 cents per bucket 
it will be seen they make fair wages. Standing just beyond 1 
the women are the machines which fill the cans. To describe- 
them would be impossible, there being so many shapes and 
many makes. Some are very good, some very poor, every 
man thinks his the best, and so it goes ; but in one respect they 
all agree : they have a hopper into which the fruit is poured* 
from the buckets, and all have the plunger which forces the 
fruit into the cans ; the treadles of some of them are moved by 
hand and some by steam. The machines rapidly fill can after 
can, which are then set on the " filling table "and receive 
" top them off," or in other words the fruit is cleared away 
from the top of the can so that the solder used in capping: 
them will not become chilled. They are then placed in trays- 
each holding either 10 or 12 cans and removed to the " wiping 
table," where everything is cleared from the top, wiped dry 
with sponges, and the cap placed over the opening. The 
" cappers " stand directly in front of the wiping table, and 
each one has his own fire-pot, irons, files, and everything he 
uses before him. Taking the tray, he rapidly applies by 


means of a small brush the acid or flux necessary to make the 
solder flow freely around the cap, and then with the iron melts 
the solder and puts it in the groove. The can is then vented 
and is ready for the "bath." The baths, except in size, are 
-constructed similarly to the scalder, and a thin cedar cover 
fits over each one. The cans are placed in wire or iron crates, 
lowered into the boiling water, and allowed to remain as long 
as necessary to cook them. The time of working varies in 
the different factories, but all the way from 30 to 50 minutes 
is required. They are then taken from the bath and placed 
on a slat-floor, where the air can pass through them, and when 
they are cold are " tested," generally by striking them with 
an awl. The testers become so expert that they can instantly 
detect by the sound an imperfect or leaking can ; these are 
thrown out, mended, re-pressed, and put back in the pile. 
The cans are now ready for the next thing, which is labeling. 

Labeling is done in different ways, and some canners with 
an idea of saving labor employ devices which are not only 
hard on the young girls who do the work, but which often re- 
sult in much confusion and poor work. The best method is 
to divide the help into parties of five, one girl sitting on one 
side of the table with paste-pan, brush, and labels and the 
other four opposite her. The one girl, if quick and active, 
will paste the ends of the labels as fast as the other four can 
put them on the cans. The table is of course alongside the 
pile of cans, and two smart boys will place the cans on the 
table. As a girl labels a can she pushes it from her, when it 
is taken by the boxer, put in the box, and nailed up. This 
mode is simple and effective, and as the gang will label from 
700 to 900 cases in a day the work progresses rapidly. 

In many of the larger factories patent processing kettles, 
capping irons, and improved machinery are used, but as the 
result is, of course, the same, and they do not affect the mode 
of packing, it is not thought necessary to enter into any de- 
scription of them. 

In the foregoing an outline of the packing process has been 


given, but nothing has been said of the many trials and vexa- 
tions of a canner's life. If everything went always smoothly, 
it would be as pleasant as any other business, but it does not. 
The canner will early in the season employ his hands and com- 
mence in a small way. He may start and run only two or 
three hours, and for that length of time boilers will have to be 
fired up, help got together, and at the close the factory cleaned 
the same as if he had run the day out. Then, as the crop 
rapidly matures, work becomes heavier, and at last the inev- 
itable "glut" commences, and he finds the products of 400 or 
500 acres of perishable fruit at his doors, maybe 50 wagons, 
each owned by an impatient farmer standing in the street wait- 
ing his turn to unload. That is the time he has need of nerve ; 
help must be secured, everything and everybody pushed to 
their utmost endurance, and from early morning until way 
into the night, day after day, the week goes on ; help succumbs, 
and machinery breaks, but the factory must move in storm 
and in sunshine. The work must go on, and at last the agony 
is over, and the crop coming in again gradually gives a little 
relief to the overworked people. 

It would be an impossibility to correctly state the amount 
of capital invested or the number of persons employed in the 
industry. The States of New Jersey, Maryland and Delaware 
pack a large proportion of the goods, the late falls and the 
nature of the soil being particularly well adapted for raising 

In connection with the canning of tomatoes it may be of 
interest to our readers to give the preparation of 

Catchups. Under the name of catchup or catsup a thickly- 
fluid sauce comes into commerce, which is used as a condiment 
with meat, and the preparation of which has become of some 
importance. Everywhere where Anglo-Saxons reside catchup 
is found, though it has also been introduced on the continent 
of Europe and in the tropics. The varieties most liked are 
tomato and walnut catchups, and immense quantities of them 
are manufactured in the American canning establishments. 


The mode of preparation is so simple that it can be introduced 
into every kitchen. 

Tomato Catchup. The receipts for making this favorite 
catchup are innumerable, and should those of every packer 
and housewife in the land be taken and put together they 
would make a good-sized volume. 

In some factories where the tomatoes are peeled and either 
canned or made into some whole tomato product, such as 
chili sauce, the trimmings are made into catchup, all decayed 
portions being rejected. The trimmings are sometimes run 
to a chopper before going to the pulping machine. In some 
plants the stock is cooked before running it into the pulping 
machine, while in others the pulp is made from raw tomatoes. 
It makes little difference which method is used, so there is no 
material delay between the time of pulping and the using of 
the pulp. At some places the pulp is run as fast as made 
into a single vat and drawn out from the same during the 
day as needed. In this way the pulp is run with some that 
may have been in the vat for several hours, and there is a 
possibility of spoilage to begin with and consequently of some 
injury to the product. If the pulp is to be stored at all, a set 
of smaller vats is preferable, so that each vat as it is emptied 
can be cleaned out before a new lot is run in, thus checking 
any fermentation that might result due to the storing of the 
pulp in the same vat throughout the day's run. 

The pulp obtained from the fruit, in making catchup is 
generally concentrated to about 50 or 25 per cent, of the orig- 
inal volume by boiling or the gravity method, the latter being 
employed by the majority of the plants making trimming 
pulp. At some plants it is customary to process the catchup 
after bottling while others find it unnecessary. 

No receipt can be given that will suit all in regard to the 
amount of the different condiments to be used as each person 
has ideas of his own, but all catchup should be made hotter 
than desired, as it will undoubtedly lose some of its strength 
when it becomes cold. The best of spices and vinegar should 


be used and every vessel into which it is put should be scrup- 
ulously clean and free from any mold or dust. Seal the 
bottles carefully, and if you have them thoroughly air-tight, 
the catchup will improve with age. 

Below a few receipts for making catchup on a small scale 
are given. 

I. Take 15 quarts of thoroughly ripe tomatoes, 4 tablespoon- 
fuls each of black pepper, salt, and allspice, 8 red peppers, and 
3 teaspoonfuls of mustard. The pepper and allspice must be 
ground fine and the whole boiled slowly 3 to 4 hours; then 
pass all through a fine sieve and when cold put it in bottles, 
which must be immediately sealed. 

II. Boil 4 quarts of tomatoes together with 2 quarts of vine- 
gar, 2 tablespoonfuls of red pepper, 4 tablespoonfuls of black 
pepper, 1 tablespoonful of cloves, 1 teaspoonful of salt, and 1 
ground nutmeg, to a thick paste. Strain through a coarse- 
meshed sieve and sweeten the sauce obtained with J Ib. of 
sugar. Fill in bottles and shake once every day for a week. 

III. Cut up perfectly ripe tomatoes and place them upon 
the fire until they commence to bubble. Then take them 
from the fire, and when cool rub them with the hand through 
a hair-sieve and season according to the following propor- 
tions : For each quart of sauce add 1 teaspoonful of ground 
allspice, 1 teaspoonful of ground cloves, 1 tablespoonful of salt, 
and 1 quart of wine-vinegar. Stir the whole thoroughly to- 
gether, replace it upon the fire, and boil for one hour, with 
constant stirring. When cool put the catchup in bottles and 
seal immediately. 

Walnut Catchup. I. In June, when the walnuts are still- 
soft, take 10 dozen of them, and after crushing pour over 
them 2 quarts of 'wine-vinegar, add the following spices, all 
ground : 2 tablespoonfuls of black pepper, 1 J oz. of nutmeg, 
40 cloves, J oz. of ginger, J oz. of mace, and boil the whole 
i hour, stirring constantly. When cold strain through a 
hair-sieve and put the catchup in bottles. 

II. Crush about 10 dozen of young, soft walnuts, sprinkle 


{ lb. of sugar over them, and then add 1 quart of vinegar. 
Let the whole stand six weeks, stirring frequently. Then 
strain through a bag, with constant pressing with the hand. 
Pour 1 pint of vinegar over the residue, let it stand over night, 
and strain again through the bag. Combine the fluid with 
that previously obtained and season with the following spices, 
all ground : 1} oz. of black pepper, \ oz. of nutmeg, J oz. of 
ginger, \ oz. of mace, and 40 cloves. Then boil J hour, strain 
through a hair-sieve and bottle. 

Cucumber Catchup. Thoroughly ripe cucumbers, before turn- 
ing yellow are peeled and grated upon a coarse grater. This 
paste is brought into a colander to allow the juice to run off, 
then pressed through a coarse hair-sieve to remove the seeds, 
and finally brought into small, wide-mouthed bottles, which 
are rilled j full. The remaining space is filled up with good 
wine-vinegar. This catchup has the taste and odor of fresh 
cucumbers, and is used as a condiment with meat. Before 
bringing it to the table it is seasoned to taste with salt and 

Horseradish Catchup. The mode of preparation is the same 
as for the preceding, putting the grated mass in a colander and 
straining through a hair-sieve being, however, not necessary. 
Both varieties of catchup must be immediately corked, sealed, 
and kept in a cool place. Within the last few years both have 
been prepared on a large scale in the United States and Eng- 
land, and have become an article of export. They are packed 
in small, wide-mouthed bottles, sealed, and provided with 
gaily-colored labels. Some English factories use small earth- 
enware pots of a cream color, closed with corks over which is 
tied strong colored paper. The pots are very good, but the 
manner of closing them is not ; the corks should be sealed. 

Currant Catchup. Heat nearly to the boiling point, with 
constant stirring, 4 Ibs. of thoroughly ripe currants together 
with 1J Ibs. of sugar. Then add 1 tablespoonful each of cin- 
namon, salt, cloves, and pepper all finely pulverized and 1 
quart of vinegar. Boil the mixture one hour and then treat 
in the same manner as tomato catchup. 


Gooseberry CatcJiup. This product also comes into commerce 
under the name of " spiced gooseberries." It is an excellent 
condiment with roast fowl. Take 6 quarts of gooseberries, 
ripe or unripe as may be desired, and carefully remove the 
steins and pistils. Then bring them into a kettle, and after 
pouring some water and scattering 5 Ibs. of pulverized sugar 
'over them, boil for 1J hours. After boiling 1J hours add 4 
Ibs. more of sugar and 1 tablespoonful each of allspice, cloves 
and cinnamon. The catchup is not strained, but brought at 
once and while warm into wide-mouthed bottles or pots, which 
are immediately corked and sealed. It is advisable before 
closing the bottles to lay a closely-fitting piece of salicylated 
paper upon the surface of the catchup. The bottles should be 
kept in a cool place. 

It need scarcely be remarked that catchup can be prepared 
not only from the above, but from all varieties of fruit, and it 
is only necessary to take one of the above receipts as a type. 
But, with few exceptions, those given are the only catchups 
prepared on a large scale and brought into commerce. 

Another subject which may be referred to in connection 
with the preservation of fruit is the preparation of 

Fruit-butter, Marmalade and Jelly Fruit-butter. The manu- 
facture of apple-butter, which may serve as a type of that of 
all other fruit-butters, is effected as follows : Fill the boiler 
two-thirds full with the juice of sweet and bitter-sweet apples 
in about the same proportion as given for the manufacture of 
cider. The other third of the boiler is filled up with slices of 
ripe, juicy apples, and the mixture boiled, with frequent stir- 
ring. When the slices of apples are so soft that they com- 
mence to fall to pieces, they are carefully removed from the 
boiler by means of a skimmer, care being had to allow the 
juice to run off. The same quantity of fresh slices of apples 
is then brought into the juice and boiled in the same manner 
as the preceding. When these have acquired the necessary 
degree of softness, the entire contents of the kettle, together 
with the slices of apples previously boiled, are brought into a 


stoneware pot and allowed to stand covered for 12 hours. 
The mass is then replaced upon the fire and boiled, with 
constant stirring, until it has acquired the consistency of soft 
soap. If desired, it can at the same time be seasoned with 
cinnamon, nutmeg, etc. To prevent scorching, the second 
boiling is effected in vessels standing in boiling water. 

In the same manner fruit-butter can be prepared from all 
varieties of fruit, pear or apple juice forming, however, always 
the boiling liquor. Apple and peach butters are commercially 
of the greatest importance, though butter of quinces, pears, 
blackberries, cherries, plums and cranberries is also manu- 
factured on a large scale. Whortleberries, which grow in 
enormous quantities in some parts of the country, might also 
form an excellent material for this product. In the foregoing 
only the varieties are mentioned which are manufactured on a 
large scale by American and English factories that chiefly con- 
trol the trade in fruit-butters, but these do not by any means 
exhaust the list. Green gages can, for instance, be highly 
recommended for the purpose. 

The excellent product brought from France into commerce 
under the name of raisine is prepared in the above manner by 
slowly boiling sliced apples and pears in unfermented grape- 

Fruit-butter is packed in wooden buckets of 5 or 10 Ibs. 
capacity and in stoneware jars. Tin cans holding 2 Ibs. are 
also sometimes used, but they are not liked. The buckets 
are slightly conical towards the top and are provided with a 
wire handle. Resinous wood should not be used in their 
construction, as it would impart an odor to the fruit-butter. 
The buckets are filled up to the edge, and a closely fitting 
round piece of paper previously saturated with concentrated 
solution of salicylic acid in whiskey is laid on top of the butter. 
The tight-fitting lid is placed upon the bucket without being 
sealed or otherwise closed. A large lable occupying the space 
between the lower and upper hoops finishes the packing. 

Marmalade. The same product is sometimes called mar- 


malade and sometimes jam. The French prepare only mar- 
malade, while the Englishman brings the same product into 
commerce as jam or as marmalade, just as it may suit him 
best, and the German is not much better. The term marma- 
lade was originally applied to a jam prepared from quinces, 
it deing derived from marmelo, the Portuguese word for quince. 
The term was gradually given to all jams in order to give 
them a more distinguished character, and this has led to a 
confusion of terms which sometimes extends even to jelly. 
There is, however, a wide distinction : Marmalade or jam is 
prepared from the pulp of fruit and jelly from the juice, while 
fruit-butter, as above indicated, is a blending of both with the 
omission of sugar. 

For the manufacture of marmalade on a large scale all the 
rules and receipts can be condensed as follows : The fruit must 
be of excellent quality, entirely free from blemishes and 
washed perfectly clean. Kernel fruit is peeled, quartered and 
freed from the cores ; peaches are also peeled, halved, and 
stoned ; other stone-fruit is only stoned and halved, while 
berries are carefully freed from the stems. Melons and pump- 
kins are peeled and cut into small pieces. Rhubarb should 
not be washed but rubbed with a moist cloth and be then cut 
into small pieces. Tomatoes are to be peeled which is facili- 
tated by previously placing them for one minute in hot water. 
Being thus prepared the fruit is brought into a copper kettle 
and as much water as is required for boiling- added. While 
the fruit is boiling, weigh off as many pounds of white sugar 
as there is fruit, soak it in water, boil and skim carefully. 
The fruit should be boiled quickly, and when perfectly soft is 
allowed to cool off somewhat and then rubbed through a wide- 
meshed hair-sieve. The mass passing through the sieve is 
combined with the sugar and replaced upon the fire. The 
whole is then boiled with constant stirring, to the required 
consistency. The latter is tested by taking a small sample 
with a wooden or bone spoon nothing else should be used 
and if it draws threads between the fingers the boiler is removed 


from the fire. The marmalade is then brought into straight 
jars, and after laying a piece of salicylated paper on top, the 
jars are iied up with white parchment paper or sometimes 
covered with a glass cover and labeled. It may be remarked 
that in the last stage of boiling the marmalade is sometimes 
flavored, which is generally effected by stirring in lemon juice, 
cinnamon, and nutmeg according to taste. The liquor ob- 
tained by boiling crushed kernels of plums or peaches is also 
often at the same time added as flavoring. Frequently the 
sugar is not treated as stated above, but added in the form of 

The quantity of sugar has above been given in the propor- 
tion of 1 Ib. to 1 Ib. of fruit. Though this is the customary 
rule, many manufacturers use only j Ib. of sugar, a method 
which can be highly recommended. In fact there is frequently 
a perfect waste as regards the addition of sugar, some adding 
even 1J Ibs. of it to the pound, whereby the taste of fruit is 
entirely lost and the product, on account of its sweetness, to 
many becomes repugnant. It may be laid down as a rule that 
in all fruit boiling no more sugar than is absolutely necessary 
should be used. The secret of the great reputation the prod- 
ucts of the principal American factories enjoy in all portions of 
the world is simply due to the fact that they use as little sugar 
as possible, whereby the products are rendered not only 
cheaper, but they retain their natural fruit taste, and that is 
what the consumer desires, and not a sugary paste having only 
the color of the preserved fruit. The durability of the product 
need not necessarily suffer if due care is exercised in its prep- 
aration. Marmalade should not be made, as it is only too fre- 
quently done, from fruit which has been gathered for several 
days and shows signs of decay. Fruit not over-ripe and freshly 
gathered should be used and the boiling finished as quickly as 
possible. By then rinsing the jars with salicylated water and 
covering the marmalade with a piece of paper saturated with 
concentrated solution of salicylic acid or with alcohol, } Ib. of 
sugar to 1 Ib. of fruit will be ample, and even J Ib. with sweet 


fruits such as pears, raspberries, etc. Independently of the 
saving of sugar, such marmalade will give better satisfaction 
than an article twice as sweet, and will keep well in a dark, 
cool place. 

Some manufacturers use glucose in large quantities in mak- 
ing jams and marmalades. Some think it cheapens the bulk 
and causes it to congeal, while others claim that it causes the 
preserve to be heavy, syrupy and stringy. 

In some factories apple pulp is used as foundation for cheap 
jams, the proportion of it employed varying according to what 
fruit is available. It is made by filling the steam-pan full of 
good cooking apples and, after turning on the steam, boiling 
them for 20 to 30 minutes. It is advisable to put some heavy 
weight on the cover of the steam-pan before turning on the 
steam to prevent it from being blown off. When boiling is 
finished take off the cover, and with a long paddle crush any 
apple that may have remained whole against the sides of the- 
steam-pan. Then replace the cover and steam for about ten 
minutes more. The pulp is then ready for immediate use or 

All berry fruit-pulp will keep best when poured boiling hot 
into glass jars that have been rinsed out with boiling water. 
Fill the jars to the top and close at once. Sterilizing in tins 
alters the color of berry fruit-pulp. Lower grade fruit-pulp, 
of which large quantities are made for stock, may be stored in 
tins holding up to 50 Ibs. as follows : The tins, which are sol- 
dered top and bottom, have a two-inch hole in the lid and are 
stood in a vessel of boiling water. When the fruit-pulp is 
boiling hot the tins are taken out in succession and filled up 
to the top, the lids being soldered on at once. The tins are 
then stood on their heads, so that the small amount of im- 
prisoned air is compelled to rise through the boiling hot pulp, 
and is thus rendered innocuous. This method is perfectly 
reliable, and large quantities of pulp can thus be prepared for 
storage in a short time. 

From France a very fine perfumed apple marmalade is- 


brought into commerce. It is prepared from equal parts of 
Calvilles and Pippins, and after boiling is sprinkled with rose- 
water or violet essence. 

The term tutti-frutti is applied to marmalade prepared from 
a mixture of different kinds of fruit. As the name implies, it is 
of Italian origin. The composition is made according to taste 
and the fruits at disposal. 

English orange marmalade is made from bitter oranges. Cut 
the fruit into halves without injuring the core, throw into 
boiling water, a few at a time, boil for several minutes and 
then cool them quickly. The flesh can be easily squeezed 
away from the rind. Heat the flesh to boiling with a suffi- 
cient quantity of water and pulp it in a mill, quarter the rind 
and cut it into thin slices, a special machine being used for 
this purpose. Blanch the slices until soft and lay them aside 
in a sieve. Next weigh out 30 parts of the pulp and 10 of 
the slices and mix thoroughly. In the meantime dissolve 54 
parts of refined sugar and 6 of syrup and heat till they ball. 
Then add the pulp and rind and boil the whole to a finish. 
The marmalade should have a golden-yellow color and be 
perfectly clear. It is filled hot into the pots and fastened 
down when cold. The orange pulp is sometimes mixed with 
half its weight of apple pulp. 

Jelly. This product is, unfortunately, often made expensive 
and at the same time spoiled by too large an addition of sugar. 
Many housekeepers do not like to prepare jellies under the im- 
pression that they require too much sugar ; but this is an error, 
because in France, in factories as well as in households, they 
use only f pound, or at the utmost f pound, of sugar to the 
pound of fruit, instead of 1 pound or even 1J pounds, as is 
customary in England, Germany, and parts of the United 
States. Moreover, the apple-jelly which is made in the United 
States and sent to all parts of the world is made without any 
addition of sugar. Instead of apples, as the raw material, 
apple-juice is used, which must be perfectly sweet and treated 
immediately after it comes from the press. A moderate tern- 


perature is absolutely necessary for success, for, if the juice 
commences to ferment and it does very rapidly in warm 
weather the keeping quality of the jelly is injured, except it 
be mixed with a considerable quantity of sugar. A tempera- 
ture of 41 F. is considered the most suitable, and if it rises to 
above 66 F. the manufacture is at once stopped. The juice 
runs directly from the press into the boiler, under which a 
strong fire is kept because the starchy matters contained in 
the juice are only converted into sugar if the boiling down is 
quickly effected. For this reason shallow pans offering a large 
surface to the fire are used. When the juice commences to 
boil it is clarified, and the acid it contains neutralized by the 
addition of one teaspoonful of elutriated chalk to each quart of 
juice. The chalk weighed off in this proportion is mixed with 
the juice, and appears in a few minutes as a thick scum upon 
the surface, from which it is carefully removed with a skimmer. 
By this operation the jelly is clarified, and all the albuminous 
substances contained in it being removed by the chalk, filter- 
ing is not required. The process is similar to the defecation 
of the juice of sugar-cane and beets by lime. The juice is now 
boiled to the consistency of 30 or 32 B., which is found on 
cooling to be the proper point for perfect jelly. It is then filled 
direct from the pan into tumblers, which are treated in the 
same manner as marmalade jars. 

Successful jelly boiling on a large scale is impossible with- 
out the use of the saccharometer. It is the only reliable guide 
for the addition of sugar, for if the product is to be protected 
from spoiling it must show from 30 to 32. If this result can 
be reached without the addition of sugar, it is so much the 

Pear and mulberry jellies are prepared in exactly the same 
manner as above. Other fruits containing more acid require 
an addition of sugar, especially currants, which next to apples 
and pears are most used for jelly, but in no case is the same 
weight of juice and sugar required. 

To prepare jelly from berries and other small fruits, pour hot 


water over the fruit in order to free it from adhering dirt and 
to facilitate the separation of the juice. When the water is 
cool take the berries out, express the juice, and bring the latter 
immediately into a copper or brass kettle over a lively fire. 
Then stir in pulverized sugar, the quantity of which varies 
according to the variety of fruit. For raspberries, strawberries, 
and blackberries J pound of sugar to the pound of juice will 
be sufficient, and f pound or at the utmost f pound for cur- 
rants, barberries, elderberries and whortleberries. The sugar 
being added, stir in the chalk in the proportion previously 
given, and after allowing the juice to boil not longer than 15 
minutes, take it from the fire and strain it at once into the 
glasses. In this manner a clear, beautiful jelly of an agreeable 
taste will be obtained. If, on the other hand, the juice is 
boiled slowly over a weak fire, the result will be a turbid 
product which has lost its fruity taste. 

Stone-fruit is boiled, and after boiling it with a small quan- 
tity of water until soft, the juice is pressed out and f pound 
of sugar added for every pound. It should be boiled quickly, 
and not, as some receipts have it, for f hour. Quinces are 
peeled and then treated like stone-fruit. Rhubarb is cut into 
small pieces and then treated in the same manner. A quite 
good jelly can also be prepared from the medlar, provided it is 
allowed to become completely ripe, and is then slowly steamed 
with a very small quanity of water. When thoroughly soft 
the juice is pressed out and f pound of sugar added to each 
quart. The mass is sharply boiled for 20 minutes, when the 
result will be a clear jelly. 

In France, as previously mentioned, perfumed marmalade is 
prepared from equal parts of Calvilles and Pippins. From the 
same material, which is considered best for the purpose, a per- 
fumed jelly is also prepared. The apples are not peeled, but 
cut into slices, and boiled with a small quantity of water until 
soft enough to be pressed in a filter-bag. To every pound of 
juice } pound of sugar is added, and five minutes before the 
saccharometer indicates 30 B., J or J pound of violet bios- 


soms is stirred into the juice, a few drops of cochineal being 
generally added to improve the color. The jelly, when 
finished, is strained through a hair-sieve into wide-mouthed 
bottles, which are corked and sealed. 

A jelly is made from raspberries, and sometimes also from 
strawberries and blackberries, in which the berries remain in- 
tact. The process consists in dissolving 2 pounds of white 
sugar in water and boiling until thickly fluid. Two pounds of 
berries are then brought into the kettle and carefully mixed 
with the sugar so as to avoid crushing. The kettle is then 
taken from the fire and allowed to stand covered for 15 
minutes, when it is replaced on the fire and the sugar boiled 
up once more. The product is kept in jars well corked and 

A description of the process of manufacturing apple jelly 
in one of the largest plants for that purpose may here be 

The factory is located on a creek which affords the neces- 
sary power. A portion of the main floor, first story, is occu- 
pied as a saw-mill, the slabs furnishing fuel for the boiler 
furnace connected with the evaporating department. Just 
above the mill, along the bank of the pond and with one end 
projecting over the water, are arranged eight large bins hold- 
ing from 500 to 1000 bushels each, .into which the apples are 
delivered from the teams. The floor in each of these bins has 
a sharp pitch or inclination towards the water, and at the 
lower end is a gate through which the fruit is discharged, 
when wanted, into a large trough half submerged in the pond. 

Upon hoisting a gate in the lower end of this trough con- 
siderable current is caused, and the water carries the fruit a 
distance of from 30 to 100 feet, and passes into the basement 
of the mill, where, tumbling down a four-foot perpendicular 
fall into a tank, tight in its lower half and slatted, so as to 
permit the escape of water and impurities, while in the upper 
half, the apples are thoroughly cleansed from all earthy or 
extraneous matter. Such is the friction caused by the concus- 


sion of the fall, the rolling and rubbing of the apples together, 
and the pouring of the water, that decayed sections of the fruit 
are ground off and the rotten pulp passes away with otHer im- 
purities. From this tank the apples are hoisted upon an end- 
less chain elevator, with buckets in the form of a rake-head 
with iron teeth, permitting drainage and escape of water, to 
an upper story of the mill, whence by gravity they descend to 
the grater. The press is wholly of iron ; all its motion, even 
to the turning of the screws, being actuated by the water- 

The cheese is built up with layers inclosed in strong cotton 
cloth, which displaces the straw used in olden times and serves 
also to strain the juice. As it is expressed from the press tank 
the juice passes to a storage tank and thence to the defecator. 
This defecator is a copper pan 11 feet long and about 3 feet 
wide. At each end of this pan is placed a copper tube 3 feet 
inches in diameter and closed at both ends. Lying between 
and connecting these two are twelve tubes also of copper, 1 J 
inch in diameter, penetrating the larger tubes at equal distances 
from their upper and under surfaces, the smaller being paral- 
lel with each other and 1J inch apart. When placed in posi- 
tion the larger tubes, which act as manifolds, supplying the 
smaller with steam, rest upon the bottom of the pan, and thus 
the smaller pipes have a space of } inch underneath their 
outer surfaces. 

The apple-juice comes from the storage tank in a continu- 
ous stream about f inch in diameter. Steam is introduced to 
the large or manifold tubes, and from them distributed through 
the smaller ones at a pressure of from 25 to 30 Ibs. per inch. 
Trap-valves are provided for the escape of water formed by 
condensation within the pipes. 

The primary object of the defecator is to remove all im- 
purities and perfectly clarify the liquid passing through it. 

All portions of pomace and other minute particles of foreign 
matter, when heated, expand and float in the form of scum 
upon the surface of the juice. An ingeniously contrived float- 


ing rake drags off this scum and delivers it over the side of the 
pan. To facilitate this removal, one side of the pan, com- 
mencing at a point just below the surface of the juice, is curved 
gently outward and upward, terminating in a slightly inclined 
plane, over the edge of which the scum is pushed by the rake 
into a trough and carried away. 

A secondary purpose served by the defecator is that of 
reducing the juice by evaporation to a partial syrup of the 
specific gravity of about 20 B. When of this consistency the 
liquid is drawn from the bottom and the less agitated portion 
of the defecator by a syphon and thence carried to the evap- 
orator, which is located upon the same framework and just 
below the defecator. 

The evaporator consists of a separate system of six copper 
tubes, each 12 feet long and 3 inches in diameter. These are 
jacketed, or inclosed in an iron pipe of 4 inches internal diam- 
eter, fitted with steam-tight collars so as to leave half an inch 
space surrounding the copper tubes. The latter are open at 
both ends, permitting the admission and egress of the syrup 
and the escape of the steam caused by evaporation therefrom, 
and are arranged upon the frame so as to have a very slight 
inclination downward in the direction of the current, and 
each nearly underneath its predecessor in regular succession. 
Each is connected by an iron supply-pipe, having a steam- 
gauge or indicator attached, with a large manifold, and that 
by other pipes with a steam boiler of 30 horse-power capacity. 

Steam being let on at from 25 to 30 Ibs. pressure, the stream 
of syrup is received from the defecator through a strainer, 
which removes any impurity possibly remaining, into the 
upper evaporator tube; passing in a gentle flow through that, 
it is delivered into a funnel connected with the next tube be- 
low, and so back and forth through the whole system. The 
syrup enters the evaporator at a consistency of from 20 to 
23 B., and emerges from the last tube, some three minutes 
later, at a consistency of from 30 to 32 B., which is found 
on cooling to be the proper point for perfect jelly. This 


point is found to vary one or two degrees, according to the 
fermentation consequent upon bruises in handling the fruit, 
decay of the same, or any little delay in expressing the juice 
from the cheese. The least fermentation occasions the neces- 
sity for a lower reduction. To guard against this, no cheese 
is allowed to stand over night, no pomace left in the grater 
-or vat, no juice in the tank ; and further to provide against 
fermentation, a large water tank is located upon the roof and 
filled by a force-pump, and by means of hose connected 
with this, each grater, press, vat, tank, pipe, trough, or 
other article of machinery used can be thoroughly washed 
-and cleansed. Hot water instead of juice is sometimes sent 
through the defecator, evaporator, etc., until all are thoroughly 
scalded and purified. 

If the saccharometer shows too great or two little reduction, 
: the matter is easily regulated by varying the steam pressure 
in the evaporator by means of a valve in the supply pipe. 

If boiled cider instead of jelly is wanted for making pies, 
sauces, etc., it is drawn off from one of the upper evaporator 
tubes, according to the consistency desired ; or it can be pro- 
cured at the end of the process by simply reducing the steam 

As the jelly emerges from the evaporator it is transferred to 
.a tub holding some 50 gallons, and by mixing a little therein 
any slight variations in reduction or in the sweetness or sour- 
ness of the fruit used are equalized. From this it is drawn 
through faucets, while hot, into the various packages in which 
it is shipped to market. 

A favorite form of package for family use is a nicely turned 
little wooden bucket with cover and bail, of two sizes, holding 
5 and 10 pounds respectively. The smaller packages are 
shipped in cases for convenience in handling. 

Each bushel of fruit will produce from 4 to 5 pounds of 
jelly, fruit ripening late in the season being more productive 
than other varieties. Crab-apples produce the finest jelly, sour 
crabbed natural fruit makes the best-looking article, and a 


mixture of all varieties gives most satisfactory results as to 
flavor and general quality. 

Saving of the Apple Seeds. As the pomace is shoveled from 
the finished cheese it is again ground under a toothed cylinder, 
and thence drops into large troughs through a succession of 
which a considerable stream of water is flowing. Here it is 
occasionally agitated by raking from the lower to the upper 
end of the trough, as the current carries it downward, and the 
apple seeds becoming disengaged drop to the bottom into still 
water while the pulp floats away upon the stream. A succes- 
sion of troughs serves to remove nearly all the seeds. 



EVAPORATION is one of the most important methods em 
ployed for preserving fruit for any length of time. The rea- 
son for this can be readily given : The process does not require 
great technical skill ; it excels in cheapness because neither 
vessels, sugar nor other auxiliaries are required ; the product 
possesses excellent keeping qualities, retains its natural flavor, 
and by many is considered healthier and more agreeable than 
fruit preserved by any other method. While much fruit is 
still dried in the sun, and large quantities of it are marketed, 
the superiority of evaporated fruit has caused a large demand 
for it, and aside from the consumption in this country, large 
amounts are shipped abroad. 

The Alden patent for evaporating fruit was granted about 
40 years ago. Like all other new inventions, some years 
were required before its merits became thoroughly under- 
stood, though at the Paris Exposition of 1878 the first prize 
was unanimously awarded to the fruit dried by that process. 
Since then it has spread from California, where it was first 


introduced, throughout the entire country, and though many 
types of evaporators are now in use, they are all based upon 
the same principle. At first only kernel and stone-fruits were 
evaporated, but at present the list includes almost every 
known fruit and vegetable. 

Before entering upon a description of the apparatus and its 
use, an explanation of the principle upon which it is based 
and the theory of evaporating fruit will be given. 

The object to be attained is not only to make the fruit keep, 
but also to retain the properties for which it is valued. This 
can only be reached by withdrawing the content of water, and 
at the same time converting a portion of the starch into sugar 
in as short a time as possible without boiling the fruit. The 
latter would injure the taste of the fruit, and slow drying gives 
a flavor calling to mind decay. The more quickly the watery 
portions are removed from thoroughly ripe fruit, the richer 
and more durable its taste will be ; and the more completely 
the oxygen of the air is excluded during this process, the more 
perfectly will it retain its color. Rapidity of the drying pro- 
cess sometimes increases the content of sugar by 25 per cent., 
and this increase is in an exact proportion to the quicker or 
slower evaporation of the content of water, always provided, 
however, the fruit does not suffer injury from the heat. 

Any one who has boiled down the juice of the maple, 
sorghum, sugar-cane, or sugar beet knows that with slow 
evaporation sugar is not formed, the content of sugar being 
then converted into acid. Now, the change of substance must 
be constantly kept in view : Starch is converted into sugar (in 
this case very largely already in the plant), sugar into al- 
cohol, and alcohol into acetic acid. This experience must also 
hold good in drying fruit. The chemical process by which 
the content of starch of the fruit, when brought into a high 
temperature, is converted into sugar, is similar to that during 
the ripening process on the tree, only it takes place more 

A few days of warm sunshine produce sufficient sugar in 


gooseberries and grapes to change the sour unpalatable fruits 
to a refreshing article of food. A few hours in an evaporating 
apparatus, in which the proper degree of heat is maintained, 
can produce a still greater change, provided the fruit be not 
placed in it before it has reached perfection in a natural man- 
ner. It must be remembered that 212 F. is the boiling point, 
and that subsequent treatment, no matter how careful, cannot 
restore the taste lost in such a temperature. Of no less im- 
portance is another point : The surface of the fruit to be dried 
must be kept moist and soft, so that the internal moisture may 
find a way by which it can readily and quickly escape, and a 
strong hot current of air must uninterruptedly pass over the 
fruit to carry off the escaping moisture. Hence, cold air must 
under no circumstances have access to drying fruit, and above 
the latter an aperture must be provided for the escape of the 
air saturated with moisture. 

The apprehension that fruit cannot be dried in a hot moist 
apparatus is refuted by the well-known scientific fact, that air 
of the temperature of the freezing point absorbs I-J-Q part of its 
weight of moisture, and that its capacity for absorption doubles 
with every 15 C.. (27 F.) of higher temperature. Thus, if 
the temperature is 59 F. it absorbs ^V parts of its weight of 
water, 81 F. ^ part, 113 F. ^ part, 140 F. ^ part, 167 F. 
i part, 194 F. i part, and 221 F. its own weight which is 
nearly equal to one pound of water to every \ cubic foot of 

The fruit would evidently never become dry if the air loaded 
with such moisture remained stationary, but set it in motion 
with a velocity of 880 feet per minute, which is equal to 20 
miles per hour, and the cause of the rapid drying, or, in other 
words, of the withdrawal of water, becomes apparent. Now if 
we figure to ourselves an apparatus of 225 cubic feet content, 
the air heated in it to 212 F. contains, according to the above 
statement, 60 pounds of water, 50 pounds of which have been 
withdrawn from the fruit, while the remaining 10 pounds were 
contained in the air prior to its entrance into the apparatus, 


because its temperature is supposed to be 62.5 F. With 
sufficient circulation to empty the apparatus every 20 minutes 
150 pounds of water will each hour be carried away from a 
quantity of fruit supposed to amount to 800 pounds. Hence, 
in 5 hours, the time generally required for apples, 750 pounds 
of moisture could be removed if present. 

Moreover, reference to a drying apparatus is not required to 
prove that heat alone does not suffice for drying. Is it not 
the wind which dries up the puddles after a rain more quickly 
than the hottest rays of the sun? The sun alone would effect 
nothing else but envelop the moist earth in a dense mantle of 
vapor destructive to both men and animals. Thus in the dry- 
ing apparatus also it is rather the current of air which dries 
than the heat, but, of course, both must work in conjunction. 
The rapidity of the process prevents decay, and causes the 
color and aroma of the fresh fruit to be retained. The greater 
advantage of this rapidity consists, however, in the conversion 
of a considerable quantity of starch into sugar, which in sweet 
fruits, such as peaches, is sometimes formed in such abund- 
ance as to appear in small congealed drops upon the surface. 

From the preceding it will also be readily understood why 
drying in the sun or in the oven must yield unsatisfactory re- 
sults. Even with favorable weather the process lasts about 14 
days. During this long time a fermentation sets in which par- 
tially destroys the content of sugar, and essentially changes the 
color and taste in an unfavorable direction. Such fruit when 
boiled tastes as if it had been preserved after the appearance 
of decay. Besides, during this process, the fruit is frequently 
selected as a breeding place by insects, in consequence of which 
it soon spoils, and when shipped to a distance resembles on 
arrival at its place of destination a heap of maggots. Such 
cases are not rare, especially if the dried fruit is shipped to 
tropical countries. 

Drying in the oven has the disadvantage that the dry heat 
immediately closes the pores of the fruit, thereby rendering the 
escape of the internal moisture very difficult. If the heat is 


not very strong the fruit remains moist in the interior, which 
causes it to spoil, and with a strong heat the surface carbon- 
izes more or less. A portion of the sweetness is lost by being 
converted into caramel, the appearance of the fruit suffers by 
the tough shriveling of the surface, and the taste is injured 
by carbonization. 

All these disadvantages are avoided by the modern evapo- 
rating process, which may be called a preservation of the fruit 
in its own juice with the assistance of steam. 

A chemical analysis of a parcel of Baldwin apples shows 
best the changes effected in the composition of fruit by dry- 
ing in the oven and by evaporation, and how the results with 
these two methods compare with each other. The first col- 
umn gives the composition of 500 parts of fresh Baldwin 
apples. The second column gives the composition of the same 
parcel of apples after being reduced to 100 parts (loss of 400 
parts of water) by drying in the oven, and a third column the 
result of 100 parts of the same parcel reduced by evaporation. 

Dried in Evapo- 

Fresh. the oven. rated. 

Water (free and fixed). . ... . 411.15 12.42 16.62 

Cellulose 9.60 10.54 10.22 

Starch 32.95 30.95 29.75 

Protein 0.75 0.80 0.76 

Pectine *...'. . . . 12.35 11.35 10.88 

Gum ."'. ., . 6.75 7.22 4.33 

Fruit acids '. . .. . 6.70 4.88 3.43 

Mineral constituents . . .' . . . . 0.85 0.87 0.78 

Chlorophyl > i ; 0.15 0.12 0.15 

Dextrin ...,. 2.10 

Grape sugar 18.75 18.75 23.08 

Volatile oils, traces 

500.00 100.00 100.00 

Attention must especially be drawn to the fact that dextrin, 
the formation of which is due to dry heat, is only found in the 
second column, and must be considered as an essential dis- 
advantage of drying in the oven. The absence of this sub- 
stance in evaporated fruit, as well as the presence of a larger 



FlG> "' 

quantity of water (chemically fixed), is to be ascribed to the 
influence of moisture during evaporation. 

As previously mentioned, many types of evaporators are 
now in use, some of them being small box-like structures of 
such a size that they can be placed on top of an ordinary 
cook-stove, while others* have a sufficient capacity for hand- 
ling fruit on a very large scale. 

Fig. 99 shows an improved Aid en evaporator which, like 
the Williams evaporator to be described later on, belongs to 
the type known as tower evaporators. A is the air-furnace 

which is formed by the fire-box D, 
the ash-box D lt and the doubled hori- 
zontal pipes G, of which, according to 
the size of the apparatus, there are 
from 3 to 6, each 4 inches in diameter, 
and running parallel to each other. 
The products of combustion pass 
through them in the direction of the 
arrows, and escape through the smoke- 
pipe at the back of the apparatus. 
The fire-box is surrounded by an air- 
space provided at M with apertures. 
Similar apertures to permit the en- 
trance of cold air are provided on the 
side near the foot of the brick casing. 
The cold air comes first in contact 
with the lower, only moderately heated 
pipe, then rises to the second, and 
finally to the third and hottest series 
of pipes. It is thus gradually heated, 
and the pipes lying close together, each 
atom of air comes in contact with them, 

which is considered a better mode of heating than by radia- 
tion, formerly used. The pipes are of cast-iron, and an escape 
of smoke into the drying-tower is impossible. By always 
keeping the pipes clean, which can be conveniently done, the 


heat passes rapidly through their walls, and ascends im- 
mediately into the drying-tower without the possibility of 

The draught-pipe d connects the exit of the drying-tower 
with the fire-box of the furnace. The importance of this ven- 
tilation is sufficiently shown by the statement that for com- 
bustion 25,000 cubic feet of air per hour are required, which 
are introduced from the neighborhood of the opening of the 
tower through the pipe d into the fire-box. The removal of 
such a considerable quantity of air produces a vacuum in the 
upper portion of the tower, and consequently a very quick cur- 
rent of air over the trays of fruit in the tower an absolute 
requirement for attaining great perfection in the art of drying 
fruit by evaporation. Besides, a saving of fuel is effected by 
the introduction of air, already heated, into the fire-box. The 
smoke-pipe is surrounded by a wooden jacket, leaving a small 
intermediate space in which the heat radiating from the pipe 
collects, and is forced to enter the tower below the discharge- 
door. This also accelerates the current of air in the tower and 
prevents the condensation of the moisture, so that the fruit 
completely dries off in a short time. The branch-pipe/con- 
nects the opening of the tower with the smoke-pipe, which by 
its power of absorption also increases the current of air. The 
draught-pipe c is provided, as will be readily seen, for the 
purpose of uniformly distributing the heat in the tower. 

The bulb of the thermometer, with which the apparatus is 
provided, is placed in the interior of the tower and the scale 
on the outside, so that the temperature can be read off without 
opening a door, whereby cold air would enter, which must be 
avoided. The air-furnace is constructed of brick, and the 
tower, as well as the draught-pipes d and c and the jacket of 
the smoke-pipe 0, of double boards. 

The hurdles or trays for the fruit consist of wooden frames 
with galvanized iron-wire bottoms. They hold from 20 to 60 
Ibs. of fruit each, and when charged are pushed through the 
door over the air-furnace into the tower, where they rest upon 


pins of an endless chain set in motion by a wheel, as seen in 
the illustration. The trays sit close to the walls on two sides 
of the tower, while in the other direction there is an inter- 
space of two inches. The first tray is pushed tight against 
the back wall, the mentioned, interspace thus remaining in 
front of the door. 

After six to ten minutes, according to the variety of fruit, 
the tray is raised five inches by means of the endless chain ; 
the second tray is then placed in position, but so that the 
above-mentioned intermediate space is at the back wall. At 
regular intervals the trays, when placed in position, are raised 
by the endless chain and the fresh trays pushed in, so that 
they touch alternately the front and back wall, the current of 
air being thus forced to ascend in a zigzag. When the tower 
is filled with trays it contains taking apples as an example 
from 1200 to 3000 Ibs. of fruit. Every 50 Ibs. of each yield 
from 40 to 45 Ibs. of water, which ascends as vapor, which by 
surrounding the fruit with a moist mantle prevents its burn- 
ing and keeps the pores open. When the tray first placed in 
position arrives at the discharge-door it has been in the tower 
for about five hours, and its contents have been converted 
into evaporated fruit which will keep for many years. Thus 
fruit can be gathered, evaporated and sold all in one day. 

By considering the construction of the tower it will be seen 
that the fruit during its ascent remains in a uniform moisture 
and heat, so that up to the moment it is taken from the appa- 
ratus, its content of water can escape through the opened 
pores and, on the other hand, the heat can act to its very 
center. A uniform, perfect product can be obtained only by 
these means. When the fruit arrives at the discharge-door it 
is cool and as soft as fresh fruit. 

Fig. 100 shows the Williams evaporator. It is heated by 
steam radiators located at the base of the vertical tower and 
has vertical radiating pipes up the center of the vertical tower, 
around which the trays of fruit revolve, with deflectors at in- 
tervals of two feet projecting from each side of said pipes to 


FIG. 100. 


direct the heat under the trays of fruit as they revolve around 
the pipes. (The trays and hanger are left out in the illustra- 
tion to show the interior arrangement of the pipes.) These 
pipes or radiators extending up the tower from bottom to top 
produce a uniform heat the entire length of the tower, and 
increase the draught by increasing the heat at the top, which 
produces a more rapid circulation than when the heat is all 
at the bottom, as with the hot-air furnace ; and the capacity 
of the apparatus is also increased in proportion to the increase 
of the heat and the draught through the tower. The trays 
of fruit in passing up the tower are exposed from one side to 
the pipes, and on descending are exposed from the other, 
which causes the fruit to dry uniformly. The tower being 
vertical the heat is utilized until it reaches the top. In this 
apparatus a very strong heat can be had throughout the en- 
tire length of the tower, without incurring any risk of fire 
from siftings from the trays, when drying cores and skins, 
falling on the hot-air furnace, which is always placed directly 
under the tower. Several sizes of this evaporator are manu- 

The manner of operating the Alden apparatus is as follows : 
The maintenance of a uniform temperature in the tower 
being essential, the thermometer should indicate 194 to 212 
F. Berries and stone fruit are to be kept somewhat cooler. 
The introduction of too much cold air into the air furnace 
must be avoided. As a rule an aperture two feet square 

The upward motion of the trays must be effected at regular 
intervals. How long these intervals are to be, cannot be 
definitely stated, it depending on the content of water in the 
fruit and on the temperature of the tower. The following 
table may, however, serve as a guide : 


Apples interval 6 to 10 minutes. 

" 12 ; 


K 15 < 



8 ' 



" 10 ' 



'4 1Q ' 



" fi ' 

" 5 c 



t < 

<i on u 


It is supposed that the temperature directly above the air- 
furnace is 212 F., and it is best to keep it at that degree ex- 
cept for berries and stoned fruit, for which it may be from 41 
to 50 less. As previously stated, it is an essential condition 
that the fruit should not boil. This will, however, not be the 
case at the temperature mentioned, because the fruit remains 
too short a time in it, and in rising upwards meets a some- 
what more moderate heat. As a rule, it may be said that as 
high a temperature as possible is most advantageous, provided 
boiling be avoided. 

The evaporated fruit, when taken from the tower, is spread 
out in an airy room, where it remains for a few hours to dry 
off previous to packing. Care must be had that during this 
time it does not come in contact with insects, and to prevent 
this the windows and air-holes should be provided with screens, 
or the fruit covered with mosquito netting. The fruit when 
ready for packing is put in boxes as follows : Line the box 
with colored paper with the ends projecting above the edge. 
Then fill the box with fruit. Kernel fruit is piled up about 
one inch above the edge of the box, while stone fruit is not 
piled so high, it being subsequently not subjected to pressure. 
To press down the contents even with the edge of the box a 
weight, or, still better, a press is used. After pressing, fold 
the ends of the paper over the fruit, nail down the lid, and put 
on the label. 

Sliced evaporated apples are packed as follows : Line the 


box with white paper, one piece on the bottom and four pie - 
on the sides long enough to fold over. Then nail down the 
lid. take off the bottom, and commence packing by placing 
one layer of slices in the manner of roof-tiles. Sufficient fruit 
to make up the required weight is then piled in, and after 
pressing down the box is nailed up and labeled. A general 
rule as regards weight has not been introduced, though in 
California all varieties of evaporated fruit are packed in boxes 
holding 50 pounds net. 

In recent years tower evaporators have been largely super- 
seded, especially for evaporating apples, by the kiln evaporator. 
This type is described by H. T. Gould* as follows : " While the 
principles of construction of the different evaporators of this 
type are similar in all cases, the details of the arrangement of 
the appliances are endlessly varied. 

" In constructing kilns the same general principles are fol- 
lowed, whether the evaporator is a small one with only a sin- 
gle kiln or an extensive establishment having several of them. 
The most satisfactory size of a kiln, all things considered, is 
about 20 feet square. This is a convenient size to fill, so far 
as the preparation of the fruit is concerned ; the heat can be 
well regulated, made sufficiently intense for the purpose de- 
sired, and evenly distributed, so that the fruit will dry uni- 
formly, and for various minor reasons a kiln of this size 
is a desirable 'unit ' in the construction of evaporators of this 

"A kiln consists essentially of a floor made of slats and 
placed over a furnace room or over a system of steam pipes. 
The floor is usually built from 10 to 12 feet above the floor of 
the furnace room. Provision should be made for regulating 
the heat by means of small openings in the base of the walls 
communicating with the outside which can be opened or 
closed as desired. The inflow of cold air can thus be regu- 
lated. Such control is specially desirable in windy weather. 

*U. S. Department of Agriculture. Farmer's Bulletin 291. Washington, 1907. 


While many evaporators are constructed without special pro- 
vision of this kind, it is an important point to have such 
openings, particularly if the walls are brick or otherwise made 
very tight, so that there is but little circulation of air. 

" If the evaporator is a frame building, the walls of the 
furnace room may be well plastered or covered with asbestos 
paper to lessen the danger from fire, which may otherwise be 
great, because of the intense heat generated within them. 

"If the walls, at least the portion below the kiln floor, are 
double, with an air-space between the two sides, the insula- 
tion will be more perfect than if they are solid or of only a 
single thickness, thus best conserving the heat and increasing 
the efficiency of the plant The height of the walls of the 
kiln above the drying floor should be sufficient to permit an 
attendant to work on the floor conveniently and with comfort. 

" Some means for the escape of the air laden with moisture 
from the fruit is necessary. This may be provided for by 
means of an opening in the roof, or a cupola-like ventilator 
may be built, the sides of which should consist of slats placed 
so that they overlap one another, as in an ordinary window- 
blind. Another form of ventilator is in the form of a tower 
about 3 feet square and extending 8 or 10 feet above the 
roof, which is sufficiently bigh to cause more or less draft, and 
hence augments the circulation of hot air through the fruit, 

The kiln floor is constructed of strips especially designed 
for the purpose. Such floors are generally made of poplar or 
basswood strips, seven-eighths of an inch thick, one inch wide 
on the top surface and one-half inch wide on the under side. 
In laying the floor these strips are placed one-eighth to one- 
fourth inch apart on the upper surface. This makes the 
space between them wider on the under side than on the 
upper, thus allowing the small particles of fruit which work 
down between them to drop through without clogging the 
intervening spaces, 

"Satisfactory results are so dependent upon the heating 
apparatus that this becomes one of the most important features 


of an evaporator. In the larger kiln evaporators, ordinary 
cast-iron stoves were formerly used considerably, two or more 
of them being frequently required to heat a single kiln, but 
these have largely gone out of use. -In their stead large fur- 
naces are now most commonly used. These are specially de- 
signed for the purpose and are provided with relatively large 
fire-pots, correspondingly large ash-pits, and large radiating 
surfaces. As it is necessary to burn a relatively large quantity 
of fuel in a given time, the size of the grate is made with this 
end in view. For a kiln floor 20 feet square, or 400 square 
feet of surface, the grate surface is usually about 3 feet in 
diameter, containing from 5 to 7 square feet. 

" As to the most satisfactory length of pipe connecting the 
furnace and chimney, opinions differ. Perhaps the most 
common method of piping is as follows : The furnace, with 
two flanges for attaching the pipe, is placed in the center ; the 
pipe from each flange is then extended to the side of the room 
opposite the chimney, and from this point the two sections, 
extending in opposite directions, follow the wall, at a distance 
of 2 or 3 feet from it, to the chimney. In a kiln 20 feet 
square, some 65 or 70 feet are thus required. Ten-inch pipe 
is a common size to use for this purpose. It is placed about 
3 feet below the kiln floor. 

" Some operators think that a better distribution of heat is 
obtained if the pipes extend back and forth, 2 or 3 feet apart, 
under the entire floor of the kiln, thus requiring 200 feet or 
more instead of the shorter length above suggested. The 
greater length, however, is less frequently used than the 

" In some cases the heat is so intense directly over the fur- 
nace that the fruit dries more rapidly in the center of the 
floor than about the sides. To regulate this and make the 
drying as uniform as possible, a ' deflector,' consisting of a 
piece of sheet iron or tin several feet square, is attached to the 
floor directly above the furnace. 

" Open grates, which in effect are furnaces with all parts 


above the grates removed, are used occasionally and are recom- 
mended by some because they require less fuel, less attention, 
to firing, and will dry the fruit in a shorter space of time. 
On the other hand so much dust rises from them that they are 
not used in making the best grade of fruit. 

" In some respects a steam system is the most satisfactory 
method of heating, but it is comparatively little used, possi- 
bly due to the larger cost of installing such a system. In. 
kiln evaporators the pipes are generally placed in as close 
proximity to the floor of the drying room as is convenient 
within a foot or even closer. That every steam pipe nearest 
the floor may supply the greatest amount of heat it should, 
have its own return to the main return of the system. One 
inch pipe is generally used for such systems. No very defin- 
ite data are available in regard to the amount necessary to 
supply the requisite heat. Several kilns, however, which are 
said to work admirably have about 600 running feet of pipe 
for every 100 square feet of floor space. One half of this is 
" riser," the other half " return". 

"A convenient arrangement for an evaporator having four 
or five kilps is as follows : The kilns are built of brick and 
the apples are pared in an adjacent building. A bin built of 
slats for containing the apples in bulk extends the entire length 
of the building, except a small space in the center where a 5- 
horsepower gasoline engine is located, which furnishes power 
for running the parers, slicers and other machinery. The 
paring table is on the opposite side of the building, from which 
the fruit is taken by a carrier and elevated to a platform which 
is on the same level as the two bleachers between the evapor- 
ator and the paring shed. This carrier discharges the fruit 
into trays which are then placed by hand into one of the 
bleachers ; from this they are taken to the slicer, located in a 
compartment just within the brick portion of the structure and 
with which all the kilns communicate, thus making it con- 
venient after the fruit has been sliced. 

" Other large establishments have the kilns arranged in a 


series situated end to end. The fruit is pared on the first 
floor of an adjoining structure centrally located ; then elevated 
to the second floor which is on the same level as the kiln 
floors, where it is bleached and sliced. Communication is 
had with the kilns not adjacent to the floor on which the fruit 
is sliced, by means of a platform extending from this floor 
along the sides of the kilns and on the same level as the kiln 

For commercial purposes the selection of the varieties of 
fruit to be evaporated must be carefully made. This ap- 
plies especially to apples and pears. As a rule, a product of 
high grade can be made from any sort which has a firm tex- 
ture and bleaches to a satisfactory degree of whiteness. Many 
evaporating plants have, like the canning establishments, 
certain favorites, for instance, of apples, the Baldwin, Bell- 
flower, Pippin, Northern Spy, of pears, the Bartlett, Clapp's 

Apples are pared with a machine. So many different styles 
of apple parers for operating either by hand or power are in 
the market that it is difficult to say which is the best. The 
more recent patterns have two or even three forks for holding 
the apples while they are being pared. The attendant puts 
an apple on one of the forks while one on another fork is being 
peeled. The apples are cored in the same operation by an 
Attachment applied to the paring .machine for this purpose. 
The fruit is automatically forced from the fork and drops to 
the table where it is next taken in hand by the trimmers, who 
cut out with a straight-back sharp-pointed knife, worm-holes, 
decayed parts and other blemishes. 

To make the fruit as white as possible it is usually bleached 
by subjecting it to the fumes of burning sulphur by means of 
a contrivance called a bleacher. The simplest form of con- 
struction consists of a box sufficiently long to meet the require- 
ments, placed horizontally, and large enough in cross section 
to admit the boxes or crates in which the fruit is handled. 
Rollers are placed in the bottom, on which the crates rest, 


which permit them to be moved along with but little friction. 
The crates are entered at one end of the bleacher, those pre- 
viously put in being pushed along to make room for the 
following ones. The sulphur is usually burned immediately 
below the point where the fruit is put into the bleacher. A 
short piece of stovepipe is placed at the opposite end for the 
escape of the fumes after they have passed through the bleacher. 

Another simple bleacher in which the fruit is handled in 
bulk (not in crates) consists essentially of a large square box, 
the interior of which is fitted with a series of inclined planes 
sloping in opposite directions to prevent the fruit from dropping 
to the bottom in a compact mass. The fruit is usually admit- 
ted at the top directly from the paring table. It then rolls 
from one inclined plane to another to the bottom, where there 
is the necessary opening, with means for closing it tightly to 
to prevent the escape of the sulphur fumes, for removing the 
fruit when it is bleached. The sulphur is burned beneath 
the lowest inclined plane. 

After bleaching, the fruit is sliced in a machine called a 
slicer, of which there are various styles. In general, a slicer 
consists of a table in which a series of knives is so arranged 
that when the apples are carried over them by a revolving 
arm they are cut -into slices about J inch in thickness. In 
the kiln-evaporator the sliced fruit is evenly spread on the 
floor to the depth of from 4 to 6 inches. It is a common 
practice to treat the floor of the kilns occasionally with tallow 
to prevent the fruit from sticking to it. Sometimes a mixture 
of equal parts of tallow and boiled linseed oil is used for this 

No definite rules can be given regarding the temperature 
to be maintained in the kiln, this being largely a matter of 
experience. Some operators consider 150 F. a suitable tem- 
perature when the fruit is first put into the drying compart- 
ment, dropping to about 125 F. as the drying process nears 

The fruit while drying in the kiln has to be occasionally 


turned to prevent it from burning and from sticking to the 
floor. For the first five or six hours it is generally turned 
every two hours or so, and more frequently as it becomes 
drier, until perhaps it may require turning every half-hour 
when nearly dry. 

When drying in the tower evaporator the trays or racks 
must not be too heavily loaded with fruit. Stone-fruit not 
freed from the stones is placed close together with the stem 
ends upwards, but only in one layer. Plums after evaporat- 
ing are generally brought into a bath of sugar-water to give 
them a lustrous and uniformly dark appearance. For this 
purpose brown sugar is dissolved in an equal quantity of hot 
water, and the prunes in a wire basket are submerged in the 
bath for half an hour. They are then spread out upon 
hurdles and packed when perfectly dry. Quartered or halved 
stoned-fruit, as well as sliced apples, are placed close together, 
edge upward, until the bottom of the tray is covered. Sliced 
pears are arranged in a similar manner. Of berries, several 
layers an inch deep may be made, but they must be covered 
with tissue paper. Grapes are but seldom converted into 
raisins in the evaporating apparatus, because the process 
would require 40 hours, it being impossible to use a tempera- 
ture exceeding 167 F. Hence it is considered more advan- 
tageous to dry grapes in the sun. .The well-known Malaga 
raisins are obtained by allowing the bunches of grapes to dry 
in the air. They are dipped for an instant in boiling water 
to sterilize them and then dried on straw in the sun. When 
the grapes have shrunk to a third or half of their original 
volume, the best are packed in the original bunches, but the 
inferior raisins are picked from the stalks before packing. 
The richer the grapes are in sugar, the less drying they need. 
In Spain the bunches are dipped into a boiling lye of wood 
ashes on which a little oil is floating. They are dipped and 
removed as quickly as possible, and the trace of oil that ad- 
heres to them gives a characteristic luster. 

Tomatoes to be evaporated in the tower evaporator are 


peeled but not sliced, and placed close together in one layer 
in the trays. Pumpkins are peeled and cut in pieces two or 
three inches thick. For several years a flour has been made 
from the dried pieces, which serves as a substitute for rice 
flour. Sweet potatoes are treated in a similar manner, their 
flour serving as a substitute for chicory. 

Green corn is first steamed on the ear for not more than five 
minutes. The grains are then picked off, placed in two-inch- 
deep layers in the trays and thoroughly evaporated, but not 
at too high a temperature, 185 to 194 F. being sufficient. 
When dry they are rubbed and passed through a fanning-mill 
to remove the hulls loosened by rubbing. The corn is packed 
in boxes holding 10, 20 and 50 Ibs. each. 

The following must also be steamed before evaporating : 
Green peas and beans, asparagus, beets, carrots, lettuce, cab- 
bage and parsnips. Vegetables are cut up with a cabbage- 
cutter, and roots in slices like apples. 

Onions are first freed from their external red or yellow peel 
and then cut into slices one-fourth inch thick with a cabbage- 
cutter. The slices are steamed for five minutes with a suitable 
steaming apparatus, which is best effected by spreading the 
slices in a two-inch-deep layer in the trays, placing the latter 
in the steaming apparatus, and immediately after the above- 
mentioned time in the evaporator. They are packed in tin 
boxes holding 50 Ibs. each, which are placed in a wooden box. 
By evaporation, 100 Ibs. of onions are reduced to 12 Ibs. 

Potatoes must be thoroughly washed. This is best effected 
in a cradle, the bottom of which is provided with wide perfor- 
ations so that the water, constantly pouring in, can run off 
quickly. The potatoes are then placed in trays, and from 
four to six of the latter, according to the size of the steaming 
apparatus, brought into the boiler. Steam is then admitted, 
and after 35 minutes the potatoes are taken out, care being 
had, however, not to steam them too much, as otherwise they 
become of no value for the evaporating process. The loosened 
peels are then rubbed off with the hand, and the peeled pota- 


toes brought into a press, the bottom of which consists of 
a perforated wooden plate or of woven wires. The lid must 
fit tight into the interior walls of the press, so that the entire 
mass of potatoes falls coarsely crushed through the bottom. 
The crushed potatoes are placed in layers two or three inches 
deep in the trays and leveled with an instrument made by 
driving small nails into a board so that their points project 
one-half inch. They are then evaporated at not too high a 
temperature 185 F. is sufficient to prevent scorching; 
taking care, however, to dry them through. The evaporated 
mass is coarsely ground in a suitable mill, and the resulting 
flour packed in zinc canisters, holding 28 and 56 Ibs. each. 
Two such canisters are placed in a wooden box and are then 
ready for shipment. 

It is of the utmost importance to select only perfectly sound 
potatoes and remove all which sour or are injured in any other 
way during the process. Success depends on the rapidity and 
regularity from the commencement to the end of the process. 
All potatoes which become cold before being brought into the 
evaporating apparatus are worthless, and the same may be 
said of those which have been steamed too long ; they are con- 
verted into paste. 

Attention may be drawn to a sun-drying apparatus shown 
in Fig. 101, which may be recommended to those who do not 
wish to employ artificial heat, and are forced to give the 
preference to as cheap an apparatus as possible. The appar- 
atus is constructed of boards and window-glass. The board 
walls, which are somewhat inclined outwardly, project above 
the panes of glass and serve, as is readily seen, for catching 
the rays of the sun. They are lined inside with tin, thus be- 
coming reflectors. The side door serves as an entrance to the 
apparatus when the panes of glass are to be cleansed or repairs 
are to be made in the interior. The trays containing the fruit 
are pushed in from the back, the entrance of each tray being 
covered by a wooden flap. According to the size of the ap- 
paratus two or three rows, each consisting of twelve trays, are 



placed alongside each other. Above the uppermost entrances 
for the trays are slides, which can be opened or closed accord- 
ing to whether the heat in the interior is to be increased or 

The apparatus stands upon a turn-table, so that the front 
can from morning to evening be exposed to the full rays of 
the sun. When the latter no longer reach the apparatus the 
reflectors, which are hinged, are laid over the panes of glass, 
which prevents the radiation of heat, and protects the fruit 
from dew. 

The time required for drying fruit in this apparatus cannot 

FIG. 101. 

be definitely stated, but on an unclouded, hot summer day, 
apples pared by a machine can be dried in eight hours. The 
product obtained is not of as good a quality as evaporated 
fruit, but it is incomparably superior to that produced by the 
primitive method of drying in the open air or in the oven. 

In conclusion it remains to say a few words about drying 
fruit in the oven, and we describe the French method, which 
is decidedly the best, as proved by the prunes brought into 
market from that country. The prunes having been sorted 
by a machine into three qualities are placed upon trays and 
exposed to the sun until the skin commences to shrivel. They 


are then placed in a bake-oven previously used for baking 
bread. If no bread is to be baked, the oven is very moderately 
heated to prevent the rapid closing of the pores and the forma- 
tion of a crust upon the surface. They are allowed to remain 
in the oven for 12 hours, when they are taken out, and when 
perfectly cold, moistened with alum water and replaced in the 
oven, which must now be somewhat hotter. After 12 hours 
they are again taken out, moistened with alum water, and re- 
placed for the third and last time, together with a dish full of 
water, in the oven, which must now be still hotter than before. 
The prunes when taken from the oven are submerged for a 
short time in a bath of sugar-water, and are then packed in 
boxes. It will be seen that this process is quite tedious, and 
the product is not so good as that obtained by evaporation. 

Besides prunes, the French bring into the market dried 
pears, which have also become celebrated. The process is as 
follows : Fine table-pears are pared, quartered, and boiled in 
sugar syrup for five minutes. They are then placed in a 
moderately warm oven, where they remain for 12 hours ; they 
are then taken out, allowed to cool off, and replaced in the 
oven, which must now be hotter than the first time, until 
sufficiently dried. 

The French method can be recommended, but it would be 
still better if it wer executed in the improved manner prac- 
ticed here and there in central England and in the New Eng- 
land States. This improvement consists in the previous boil- 
ing of the fruit, which must, however, not be continued 
longer than five minutes. The fruit is not gradually heated, 
but submerged in boiling water for five minutes, and, with- 
out being allowed to cool, brought at once into a moderately 
hot oven. Steaming instead of boiling the fruit is still bet- 
ter. It exposed to the steam for not longer than 
five minutes, and must then as quickly as possible be brought 
into a moderately hot oven. 




Pickles. Enormous quantities of pickles are brought into 
commerce, especially by American and English factories. 
The most remarkable varieties are piccalilli or Indian pickles, 
mixed pickles and walnut pickles. The packing is always the 
same, some of the oldest and largest English factories still ad- 
hering to stoneware pots, which have the advantage of entirely 
excluding the light from the product, thus contributing to its 
keeping quality. Both the French and Americans use glass 
bottles, the chief difference being in the diameter of the mouth, 
which is smaller in the American bottles. The latter style is 
to be preferred, because in the former the pickles, when fre- 
quently opened, are more exposed to the air than is good for 
them. Stone pots, which are no doubt best for family use, are 
too expensive for commercial purposes, not only as regards 
the first cost, but also on account of their weight, which in- 
creases the cost of transportation. The bottles are always 
provided with neat lables, and the corks generally covered 
with tin-foil. 

The following general rules apply to the preparation of 
pickles : The best quality of fruit must be gathered at the right 
time, washed in fresh cold well-water, and placed for some 
time in strong brine. They are then laid upon fruit hurdles 
to completely dry in the air, and finally brought into the bottles, 
which must be nearly filled. The interspaces are then filled 
up with hot-spiced vinegar, and the bottles immediately corked, 
and, when cold, sealed. Strong vinegar must be used, the 
manufacturers generally employing wine-vinegar, known in 
commerce as No. 24. Fruit-vinegar, clarified and spiced and 
evaporated to three-fourths its volume, also answers very well. 
Pickles for immediate use are soaked in hot brine, but as a 
commercial article they must be treated with cold brine only. 


Moreover, hot brine must not be used for vegetables of a soft 
and juicy nature such as cabbage and cauliflower ; and besides, 
cold or only slightly heated vinegar should be poured over 
such articles. Soft and delicate fruits must, as a rule, not re- 
main as long in the brine as hard and coarse-fibred ones ; and 
the softest are most advantageously pickled by pouring cold 
spiced vinegar over them. The same may be said of red beets 
and other roots which are cut into strips. Sometimes the spice 
is put whole into the bottle, but it is better and more econom- 
ical to bring it powdered into the vinegar while heating the 
latter, or if the vinegar is to be used cold, to previously boil 
the powdered spice in a small portion of the vinegar, and 
when cold add it to the rest. The spiced vinegar is prepared 
as follows : 

To 1 quart of vinegar add 2J ounces of salt, J ounce of 
black pepper, and 2J ounces of ginger. Let the mixture boil 
up once or twice in an enameled iron pot, filter through a 
flannel cloth, and pour the liquid, hot or cold, over the fruit. 

For a more strongly spiced vinegar reduce in a mortar 2 
ounces of black pepper, 1 ounce of ginger, and J drachm of 
cayenne pepper, and for walnuts, 1 ounce of eschalots, and add 
to the mixture in a stoneware pot, 1 pint of vinegar, and tie 
up the pot with a bladder. Place the pot for three days near 
the fire, shaking it several times, and then pour the contents 
upon the fruits by allowing it to run through a filtering cloth. 

In the preparation of pickles the use of metallic vessels must 
be avoided, the vinegar as well as the brine dissolving copper, 
brass, and zinc, and becoming thereby poisonous. Ordinary 
earthen pots should also be mistrusted. Stoneware pots, which 
can be heated in a water-bath or upon a stove, are best for the 
purpose. Moreover, air and light must be kept away from the 
pickles as much as possible, and they should be touched only 
with wooden or bone spoons. An essential condition for suc- 
cess is to treat the fruits immediately after being gathered. 
The method of some manufacturers, who add verdigris to the 
pickles or boil the vinegar in a copper boiler until it is suffi- 


ciently "greenish" to communicate its color to the product, 
cannot be too strongly condemned. That this crime against 
the health of the consumer is unfortunately committed to a 
considerable extent is conclusively proved by numerous chem- 
ical examinations made in the large cities of Europe and the 
United States, and undertaken with the laudable purpose of 
bringing the adulterators of food to justice. Many of the 
pickles in the market and most of the imported canned peas 
contain copper, and this notwithstanding the fact that there 
are very innocent means for coloring pickles green, it being 
only necessary to put a handful of spinach or grape leaves in 
the boiling vinegar, which acquires thereby a green coloration 
and communicates it later on to the pickles. 

The following list comprises the fruits and vegetables which 
are chiefly used for the preparation of pickles in factories : 

Barberries. The berries are gathered before they are ripe 
and washed with salt water. The vinegar is added cold. 

Beans. Cold vinegar is poured over the young pods, pre- 
viously soaked in cold water. 

Cabbage, Red and White. The heads are cut up into fine 
strips, which are placed in a strong brine for two days, then 
dried upon hurdles for twelve hours, next brought into bottles, 
and after pouring cold vinegar upon them, at once sealed up. 

Cauliflower. The heads are broken up into small pieces, 
which are placed in brine, and finally treated with hot 

Cucumbers. Young cucumbers are placed in salt water for 
one week. The brine is then poured off, and after being made 
boiling hot is poured back over the cucumbers. The next 
day the cucumbers are dried upon a sieve, slightly rubbed 
off with a cloth, and then boiling vinegar is poured over them. 

Elderberry Flowers. The umbels are gathered just before 
the flowers open, and treated in the same manner as cauli- 
flower. These pickles are much liked in England. 

English Bamboo. Young elder shoots are freed from the 
bark, placed in a brine for 12 hours, and after drying brought 


into bottles and hot vinegar is poured over them. They are 
highly esteemed as an addition to boiled mutton. 

Gooseberries. The unripe fruits are treated like cauliflower. 

Mixed pickles are a mixture of young, tender vegetables, 
preserved separately, each at the proper season, and sto