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Disinfection and Disinfectants
AN INTRODUCTION TO THE STUDY OF.
Digitized by the Internet Archive
in 2007 with funding from
IVIicrosoft Corporation
http://www.archive.org/details/disinfectiondisiOOrideuoft
Disinfection and Disinfectants
(AN INTRODUCTION TO THE STUDY OF).
TOGETHER WITH AN ACCOUNT OF THE CHEMICAL SUBSTANCES
USED AS ANTISEPTICS AND PRESERVATIVES.
SAMUEL RIDEAL, D.Sc.(Lond.),
FELLOW OP UNIVERSITY COLLEGE, LONDON; FELLOW OF THE INSTITUTE OF CHEMISTRY AlTD
OP THE CHEMICAL SOCIETY; MEMBER OP THE SANITARY INSTITUTE OP GREAT BRITAni
AND OP THE SOCIETY OP PUBLIC ANALYSTS ; EXAMINER IN CHEMISTRY TO THE
ROYAL COLLEGE OP PHYSICIANS ; FORMERLY LECTURER ON CHEMISTRY
IK ST. GEORGE'S HOSPITAL MEDICAL SCHOOL; PUBUC ANALYST
FOR THE LEWISHAM DISTRICT BOARD OF WORKS, ETC.
LONDON:
CHARLES GRIFFIN AND COMPANY, LIMITED.
PHILADELPHIA : J. B. LIPPINCOTT COMPANY.
1895.
[All Rights Reserved.]
PREFACE.
No recent attempt has been made to summarise and review
the very voluminous literature on the subject of Disinfection
which is scattered through our own and foreign Scientific and
Medical publications, and, notwithstanding the rapid develop-
ment of Sanitary Science in this country, there does not exist
at the present time, in the English language, any book which
deals exclusively with the composition of Disinfectants.
The present volume may, therefore, supply a want which
has been felt, not only by the chemist and bacteriologist, but
also by all those who, like medical officers of health and
borough surveyors, are concerned with the practical work of
Disinfection.
Owing to the attention which has been given to bacterio-
logical science during the last ten years, the methods of
Disinfection are now being reviewed under the more exact
conditions which this knowledge has rendered possible. The
time is not far distant when the importance of the thorough
disinfection of all suspected areas will be fully realised by
local authorities, and when all such work will be entrusted
to specially qualified men, instead of being regarded as a
subsidiary duty of the inspector of nuisances. The Sanitary
Institute of Great Britain has for some years insisted that
the duties of a Sanitary Inspector are such as to necessitate
a considerable amount of practical experience and scientific
knowledge. If, as at present, the proper carrying out of the
work of Disinfection forms part of their duties, the responsi-
bility of such men is considerably augmented.
It has become customary in many districts for the public
b
PREFACE.
Analyst to advise the sanitary committee on the chemical
composition of new disinfectants, and, although this practice
should without doubt he generally adopted, it must not be
forgotten that a continuous control over the strength and
bactericidal activity must be maintained after any particular
disinfectant has been finally selected.
The laudable attempts of the medical oflScers of health in
some districts to stamp out sporadic outbreaks of infectious
disease so soon as they are notified to them, are to a con-
siderable extent nullified by the slackness which obtains in ,
neighbouring areas, where a lavish display of untested disin-
fectant powders in the street gullies, or the use of a strongly
smelling or high-coloured fluid of unknown composition, is
relied upon to satisfy the public demand for hygienic condi-
tions of life.
The following pages may help in discriminating between
useful disinfection and the futile attempts which give a false
sense of security to many localities in the time of danger.
I am indebted to Mr. H. B. Ransom, A,M.Inst.C.E., for the
principal portion of the chapter on Disinfection by Heat,
and his practical acquaintance with the engineering details
of difl'erent forms of disinfecting plant has enabled me to
give this section much greater value than it otherwise
would have possessed. For several suggestions and the account
of methods for the bacteriological examination of disinfectants,
I have to thank my former colleague. Dr. C. Slater, of
St. George's Hospital; and my thanks are also due to
Dr. Louis Parkes, the Medical Officer of Health for Chelsea,
for advice and for his kindness in reading the proof sheets.
SAMUEL RIDEAL.
Westminster, June, 1895.
TABLE OF CONTENTS.
Chapter I.— Introductory.
Definition of terms,
Primitive modes of disinfecting, .
Disinfection in the Middle Ages, .
Bacteriology, . . . .
PAGE
1
2
3
.3
Methods of dealing with bacteria,
1. By exclusion,
2. ,, removal,
3. ,, destruction, .
PAOB
5
5
7
Chapter II.— Mechanical Disinfection.
lusufficiency of deodorisation.
7
Ashes and cinders, .
13
Light,
8
Gypsum
13
Mechanical purification
of gases
Sand filtration, .
14
and liquids, .
10
Stone filters, .
15
Carbon, .
10
Clark's softening process.
16
Sawdust,
13
Other ,, processes,
15
Clay,
13
Desiccation,
16
Infusorial earth,
13
Chapter III.— Disinfection by Heat.
Heat as a disinfectant, . . 19
Conditions required in a disinfector, 23
Modes of dealing with disinfection, 27
Time and steam conditions re-
quired for disinfection, . . 29
Experiments on the penetrating
power of steam, ... 33
English apparatus— Washington-
Lyon's patent, ... 34
Typ«s of disinfectors used on the
Continent, .... 42
1. Austria — Thursfield's appar-
atus, ....
2. France— The Equifex stove,
3. Denmark — Reek's apparatus,
4. Germany — Schimmel's and
Budenberg's ap])aratus.
United States,
Public installations, .
Plan of a disinfector house.
United States,
42
44
47
48
52
52
52
56
Chapter IV.— Chemical Disinfectants —The Non-MetalliC:
Elements and their Derivatives.
Halogens and their compounds.
57
Periodates, ....
76
Chlorine,
57
Organic compounds containing
Chloride of lime and hypo
the halogens.
76
chlorites, .
63
Chloroform, ....
76
The "Hermite" process.
67
Bromoform, ....
76
Chlorates,
69
Iodoform, ....
76
Hydrochloric acid, .
69
Ethyl iodide, . . . .
77
Chlorides, ...
70
Organic compounds containing
Bromine
70
iodine
78
Iodine, ....
73
Fluorine, ....
78
Iodine trichloride, .
74
Fluorides
79
lodates,
75
CONTENTS.
Chapter V.— The Non-Metallic Elements and their
Derivatives ^(cow^mMeti).
Oxygen,
Ozone,
Peroxide of hydrogen,
Nitric acid and oxides of nitrogen,
Nitric acid,
Nitrogen trioxide,
; Nitrites, .
Nitric peroxide,
Nitrous ether.
Sulphur and its compounds,
> Sulphuretted hjdrogen, .
Sulphur dioxide.
Sulphites,
Thiocamf,
Sulphur fumigation,
PAGE
79
SI
84
87
87
88
89
89
90
91
93
94
94
Sulphites in food, .
Sulphuric acid,
Sulphates,
Bisulphide of carbon.
Boric acid and borates.
96
97
98
98
99
Boric acid,
99
Borates, ....
100
Borax, ....
100
Ammonium borate,
101
Boroglycericle,
Potassic borotartrate,
101
102
Benzoboracic acid, .
102
Tests for borates.
103
Influence of gases on putrefaction, 104
Carbon dioxide, . . . 104
Chapter VL— Metallic Salts.
Salts of the alkalies and alkaline
Zinc sulphocarbolate,
113
earths, ....
. 106
,, salicylate.
113
Sulphate of lime,
. 107
Copper,
113
Carbonate of lime, .
. 107
Cuprous chloride,
114
Quicklime,
107
Cupric ,,
114
Slaked lime,
107
,, sulphate,
115
Sodium carbonate, .
. 108
Verdigris,
115
Ammonia,
109
Iron, .
116
Ammonium carbonate.
109
Metallic iron, .
116
Zinc,
109
Ferrous sulphate.
118
Oxide of zinc, .
109
Ferric sulphate,
120
Chloride of zinc,
109
,, chloride,
121
Zinc nitrate, .
111
Manganese,
122
,, sulphate, .
111
Peroxide of manganese,
122
„ acetate, .
113
Manganates and permanganate
s, 123
,, sulphite, .
113
Potassium permanganate.
124
:Chapter VII.
—Metallic Salts (continued).
Aluminium salts.
127
Basic acetate of lead,
134
Use in sewage precipitation.
128
Mercury compounds, .
135
Aluminium chloride.
131
Mercuric and mercurous nitrate
s, 135
,, acetate,
132
,, chloride, .
135
„ sulphites,
132
, albuminate,
141
Chromium,
132
, iodide.
141
Chromic acid, .
132
, cyanide, .
142
Potassium bichromate.
132
, zinc cyanide.
142
Arsenic, . . -. .
133
, chloroamide.
143
Arsenious acid.
133
, organic compounds, .
143
Potassium arsenite, ;
133
Compounds of various metals.
144
Sodium arsenite,
133
Tin — stannous chloride, .
144
Acetoarsenite of copper, .
133
Bismuth subgallate (dermatol),
144
Arsenious sulphide.
134
Silver nitrate, . . . .
144
Arsenic acid, ....
134
Osmic acid, . . . .
144
Lead, . . . ; ,
134
General remarks on disinfectants.
145
Nitrate of lead,
134
CONTENTS.
IX
Chapter VIII
.—Organic Substances.
PAQK
PAQM
Tar and its products, .
147
Pixol, ....
163
I. Hydrocarbons, .
148
Pixene
163
Naphthalene, .
148
Tricresol,
164
Anthracene,
148
Jeyes' disinfectant, .
165
Petroleum,
148
Creolin, ....
166
II. Phenols, ....
149
Essets' fluid, .
166
III. Basic substances.
149
Saprol, ....
167
Phenol or carbolic acid,
149
Izal
169
Phenol,
149
Europhene,
171
Carbolic powders, .
154
Resorcinol,
171
Carbolised solution, oil, and gauze
, 155
Pyrocatechol, .
172
Carbolic wool, ....
155
Pyrogallol,
172
Danger of phenol in surgery, .
156
Wood- tar derivatives, •
173
Carbolic soaps.
156
Pyroligneous acid, .
173
Various preparations.
156
Stockholm tar.
173
Halogen derivatives of phenol, .
157
Retinol, ....
174
Parachlorophenol, .
167
Resol, ....
174
Tribromophenol,
157
Wood creosote,
174
lodophenols, ....
157
Guaiacol, ....
175
Sulphuric derivatives,
157
,, carboxylate,
176
Sulphocarbolates, .
158
Creosol, ....
176
Sozo-iodol, ....
158
Little's soluble phenyle, .
176
Aseptol, .....
158
Naphthalene derivatives, .
177
Sozal,
158
Naphthalene, .
177
Benzene sulphonic acid, .
159
Naphthalene-sulphonic acid.
177
Phenyl-substituted fatty acids,
159
Naphthols,
177
Cresol and the higher phenols, .
160
Betol, .
179
Creosote oils, ....
160
Microcidine,
179
Creosote,
161
Alumnol, ....
179
Bacillite, .....
162
Hydronaphthol,
179
Lysol,
162
Oxynaphthoic acid, .
180
Chapter IX.— Organic Substances {continued).
Nitro-compounds,
180
Apyonin,
187
Nitro-benzene,
181
Furfurane,
187
Nitro-phenols,
181
Furfurol,
187
Trinitro-phenol,
181
Thiopheue,
187
Nitro-cresol, .
182
Pyrrol, ....
188
Nitro-glycerine,
, 182
lodol
188
Nitro-cellulose,
182
Antipyrin,
. 188
Amido-compounds,
182
Pyridine group, . . -.
. 189
Ammonia,
182
Conine, . •. . .
190
Hydroxylamine,
183
Piperine,
190
Hydrazine,
183
Pyridine,
190
Methylamine, .
183
Nicotine,
192
Dimethylamine,
183
Indole
192
Trimethylamine,
183
Tyrosine,
192
Propylamine, .
184
Qninoline derivatives.
192
Amylamine,
184
Quinoline,
192
Aminol, ....
184
Diaphtherin, .
193
Aniline, ....
184
Oxyquinoline, .
193
Acetanilides, .
185
Loretin,
193
Aniline dyes as antiseptics.
185
Thalline, . . . .
193
Methyl violets.
186
Quinine,
194
Pyoctanin, . . . .
186
Antiseptol, . . . .
194
X
CONTENTS.
Chapter X.— Organic Substances (continued).
PAGE
PAas
Benzoic acid group,
. 195
Styrone, ....
. 205
Benzoic acid, .
. 195
Sodium dithiosalicylate, .
Thymol, camphors, and essentia
. 205
Listerine,
. 197
il
Benzoic aldehyde.
. 197
oils
. 206
Sulphobenzoic acid,
. 197
Turpentines, .
. 207
Benzosol,
. 197
Thymol
. 208
Benzo-jiaracresol,
. 198
Listerine,
209
Benzo-naphthol,
. 198
Aristol, ....
209
Salicylic acid,
Oil of wintergreen,
. 198
Menthol,
. 209
. 199
Oil of cloves, .
. 209
Salol, .
. 199
Oils of caraway, cinnamon, &c
., 210
Salophen,
. 199
Essence of hops.
. 210
Phenosalyl,
. 200
Terebene,
. 210
Salicylic acid as an a
mtiseptic, 200
Camphor,
211
Lactacidine,
. 202
Eucalyptol,
211
Salicylic acid as a pi
•eservative, 202
Eucalypto-resorcin, .
212
Antiseptic tablets,
. 204
Myrtol, ....
. 212
Salicylated gauze,
. 204
Terpin hydrate.
212
Anisic acid,
. 204
Terpineol,
. 212
Cinnamic acid.
204
Borneol, ....
. 212
Styracol,
. 205
Camphoid,
. 213
Phenol-propionic aci
d, . . 205
Oxidising power of essential oils, 213
Gallic acid.
. 205
Sanitas preparations.
. 215
Tannin, .
. 205
Pinol
. 218
Chapter XI.— Compounds Related to the Alcohols.
Methyl alcohol, .
. 219
Pyroligneous acid.
. 226
,, chloride.
. 219
Glycerine, ....
. 226
Formic aldehyde.
. 219
Oleic acid, ....
. 227
Other aldehydes,
. 223
Petroleum and paraffins,
. 227
Alcohol,
. 223
Vegetable acids, .
. 227
Formic acid.
. 225
Oxalic acid,
. 228
Acetic acid,
. 225
c
hapter XII.— Pr
•aetieal Methods.
Sanitary administratio
n, . . 228
Earth-closets,
. 238
Sewers and drains.
. 229
Pail system.
. 239
Ashpits and dust-holes
. 231
Privies, ....
. 239
Houses,
. 231
Cesspools, ....
. 240
Hygienic wall-papers,
. 231
Streets, ....
. 241
Furniture and woodwt
)rk, . . 232
Wood paving.
. 242
Sinks, .
. 232
Urinals
. 242
Sick rooms.
. 232
Stables, pig-styes, and cowsheds
, 24S
Isolation,
. 232
Slaughter-houses,
. 243
Clothing, .
. 232
Bakehouses,
. 243
Excreta, .
. 233
Pigeon and fowl houses, &c. ,
. 243
Light and air, .
. 233
Cats,
. 244
After-disinfection,
. 234
Vehicles, ....
. 244
a. Phenol, .
. 234
Skins, furs, wool, hair.
244
b. Sulphurous aci(
i, . .234
Bags,
. 244
c. Chlorine, .
. 234
Disinfection of air.
. 245
d. Non-volatile di
sinfectants, 235
Apparatus for sewer gas,
. 246
Clothes, bedding, &<
5., . . 236
Vaporisers,
. 246
Hos])itals, .
. 236
Water, ....
. 247
Cisterns, , . .
. 237
Preservation of timber.
. 250
Water-closets,
. 237
CONTENTS.
XI
Chapter XIII.— Personal and Internal Disinfection-
Food Preservation.
PAOB
Personal disinfection, . . . 252
Disinfection of cavities of the
body, .... 254
a. Washing oat, . . . 254
b. Spraying, . . . 254
c. Gargles, .... 255
d. Injectionsof gases or vapours, 255
e. Inhalations, . . . 256
Antiseptic dressings, . . 256
Gauzes and wools, . . 256
Antiseptic hypodermic injections, 257
Antiseptic soaps, . . . 257
Mouth washes and tooth powders, 258
Ointments, .... 259
Respirators, .... 259
Internal disinfection, . . 259
„ antisepsis, . . . 260
Vaccination, .... 262
Preservation of food, . , . 262
Causes of change in food, . 262
1. By oxidation, . . . 262
PAOR
2. By reduction, . . . '262
3. By metallic contamination, 263
4. By organisms, . . . 264
Drying, 265
Smoking, 265
Cold 266
Preservation by chemicals, . 287
„ ,, heat, . . 268
1. The chloride of calciam
process, . . . 269
2. The Aberdeen process, . 269
3. Jones's vacuum process, . 269
4. Salzer's Baltimore process, 269
5. Budenberg's flesh steriliser, 271
6. G. Hartmann's process, . 272
7. Formaldehyde „ . 272
Milk, 272
Condensed milk, . . . 273
Butter, 274
Cheese, 275
Wheat— Bread, . . 275
Cliapter XIV.— Legal Statutes and Regulations.
Duties of a medical officer of
health, .....
Sanitary inspectors.
Public Health Act, 1875, .
Hospitals for infectious diseases.
Prevention of epidemic diseases,
Mortuaries, ....
Port sanitary authorities.
General order L. G. Board on
cholera, ....
Regulations as to detention,
Dairies, Cowsheds, and Milkshops
Order, 1885
Regulation of bakehouses, .
Housing of the Working Classes
Act, 1890, ....
Public Health (Water) Act, 1878,
Vaccination Acts, 1867, 1871, 1874,
Burial regulations.
Merchant Shipping Acts, 1854
to 1876,
Canal Boats Acts, 1S77, 1884, .
Infectious Diseases (Notification)
Act, 1889, ....
Infectious Diseases (Prevention)
Act, 1890, ....
Public Health Amendment Act,
1890
Public Health (London) Act, 1891,
Memorandum on hospital accom-
modation, ....
Memorandum on ambulances.
Rules for hospitals for infectious
277
diseases,
286
277
Circular of the medical officer
277
(L. G. Boardi, ....
286
279
Suggestions of the Society of
279
Medical Officers of Health,
288
280
Model bye-laws as to cleansing,
280
&c. ,
Model bye-laws as to nuisances
290
280
and animals, ....
290
280
Model bye-laws as to buildings, .
290
Metropolitan Asylums' Board, .
291
281
Legislation as to vagrants, .
291
282
Systems in other countries,
291
Brussels,
291
282
Germany (Berlin), .
292
282
(Leipzig), .
292
282
Vienna,
293
282
Denmark, ....
293
Disinfectants,
293
282
Special rules for disinfection.
294
283
1. Discharges, ....
294
2. Privies
294
283
3. Clothing, ....
295
4. Furniture, ....
295
283
5. Rooms, &c..
296
6. Persons attending patients,
297
284
7. Drinks
297
284
American Public Health Associa-
tion,
297
285
Quarantine, ....
298
286
Italy,
299
xu
CONTENTS.
Chapter XV.— Methods of Analysis.
A. Bacteriological methods,
Determination of the antiseptic
value, ....
I. Examination of soluble
antiseptics in solution,
Precautions,
[I. Examination of the vapours
of volatile fluids,
III. Examination of gaseous
antiseptics.
Determination of the germicidal
value,
Principle of the methods,
Relative value of tests, .
(a) Sternberg's method,
(b) Drop „
(c) Thread ,,
PAOE
^
PAaB
300
Examination of gases and
vapours, .
306
302
Fischer and Proskauer's
method, .
306
302
302
B. Chemical methods —
Chloride of lime.
308
303
Sulphites and sulphurous acid,
309
Peroxide of hydrogen,
309
.303
Boric acid, ....
309
Permanganate,
310
303
Phenol,
310
303
Tar preparations,
311
304
Carbolic powders, .
312
305
Salicylic acid and other preser
305
vatives in foods, .
314
305
Medicated wools.
316
Bibliography, 317
Index 323.
DISINFECTION AND DISINFECTANTS.
CHAPTER I.
INTRODUCTORY.
Definition of Terms — Primitive Methods of Disinfecting — Bacteriology — The
Methods of dealing with Bacteria by Exclusion, Bemoval, and Destruction.
Definition of Tenns. — The words *' disinfectant " and " disinfection "
have in recent years been used in such a variety of ways, and with
such wide application, that much confusion has arisen as to the
exact meaning of these terms.
Before the germ theory was universally accepted, the term "disin-
fection" was used to include the destruction of infectious matter and
the removal of any noxious odours to which such matter gives rise.
It was applied to the action of any substance which served as a mask
for noxious odours, and many substances which have a powerful
odour have probably become popular, as disinfectants, solely from this
cause. After the germ theory had offered a plausible explanation of
the origin of disease, it became possible to define a disinfectant as a
germicide. Disinfection then ceased to mean simply "purification,"
but acquired the special meaning of " sterilisation." A true disin-
fectant, therefore, must not only mask the smell, but must destroy
or kill the germs which give rise to it. Many poisons have the
property of killing germs as well as acting upon the higher forms of
life, and could, therefore, be used as universal destroyers of life ; but,
in many cases when disinfection is resorted to, it is desirable to
use some agent which will discriminate between useful life and in-
fectious matter. Such an ideal disinfectant should, therefore, be a
substance that will kill those germs which act injuriously on the
higher forms of life, without having any marked action upon such
higher forms. A disinfectant must likewise be efficient in destroying
the spores of pathogenic organisms, which, as a rule, are more
resistant than the germs which form them. From this de6nition it
1
2 DISINFECTION AND DISINFECTANTS.
will be seen that a disinfectant does much more than prevent decom-
position, and does more than remove the noxious smells which often
emanate from putrefying matter. A disinfectant really goes to the
source of the trouble, and, by killing the organism, prevents the
spread of epidemic disease. An antiseptic, on the other hand,
prevents animal or vegetable substances from undergoing decom-
position, and a body is said to be aseptic when it is in a condition
of sterility. A substance which has the property of absorbing the
unpleasant odours which are emitted from matter undergoing decay
is called a deodorant, and such substances must be carefully distin-
guished from true disinfectants. Most disinfectants are deodorants ;
but a deodorant, unless of a permanent character, is not an antiseptic.
It is true that in most cases a noxious smell accompanies decay, and,
therefore, that any substance which permanently removes the smell
must necessarily cause the cessation of the decay ; but in other cases
in which there is no appreciable odour, a deodorant would not be
required. Charcoal is an example of a body that will absorb any
' unpleasant smell which may arise from organic matter, but which
does not kill the germ producing the decay. Although commonly
called a disinfectant, it should be more properly classified among the
deodorants.
Primitive Methods of Disinfecting. — Man has an instinctive repugnance
to all noxious odours, and from the earliest time has sought to mask
their presence by the use of aromatic substances. The use of perfumes
is probably a relic of the effort of primitive man to counteract this
evil. Many religious ceremonies, such as the burning of incense, have
also the same origin, and embalming, as practised by the Egyptians,
is a good example of successful attempts to arrest putrefaction in very
early ages. Sulphur has been employed from the earliest times, and
Homer describes its use in religious ceremonies. In the time of
Hippocrates, sulphur was regarded as an antidote against the plague.
Ovid makes mention of the fact that sulphur was employed by the
shepherds of his time for bleaching fleeces and for purifying their
wool from contagious diseases. During the plague of Athens, Acron,
according to Plutarch, stayed the spread of the epidemic by lighting
fires in the middle of the public places and in the streets where deaths
had occurred ; and the lighting of fires during times of plague has been
customary until quite recent times.
The Mosaic law, with all its minute instructions as to the purifica-
tion of the people and their belongings, shows the same combination
of religious ceremonial and sanitary precautions ; this law, undoubtedly,
contributed to the permanency of the Jewish race during its early
liistory. The Indian who, instead of embalming or burying his dead
INTRODUCTORY. 3
friend, hangs the body under a tree exposed to the air, makes use of
the property of desiccation, which, as is well known, is very efficient in
arresting decay, and is the basis of a modem patent for keeping yeast.
Earth is a very powerful deodorant and will also act as an antiseptic ;
the gases given off by decaying bodies are absorbed, and thus the
burying of a body under proper conditions may be regarded as an
efficient means of disinfection. The use of fire for cremating bodies
undergoing decay or likely to cause a nuisance is, of course, an illustra-
tion of the employment of heat for the destruction of micro-organisms.
Disinfection in the Middle Ages. — During the long period of the
Middle Ages, the alchemists did little to advance our knowledge of
this subject ; they collected a few facts, and described, with more or
less accuracy, the properties of some of the more important chemical
compounds ; but one may search in vain for a correct account of any
example of preventive medicine. Notwithstanding the ravages of the
cholera, the plague, and other epidemics, as well as the frequency of
leprosy, the idea of contagion was only imperfectly understood, and
the common people were far less cleanly in their habits than the Jews,
for example, or heathen nations who, as we have already mentioned,
mingled primitive sanitary precautions with their religious services.
Perhaps one of the earliest papers of any importance which we have is
a Memoire sur les substances septiques et aniiseptiques, written by Pringle
in the middle of the eighteenth century. In this Memoire some forty-
eight experiments are described, in which the author took pieces of
fresh meat and placed them in contact with various amounts of sub-
stances which be believed to have an antiseptic action. Amongst the
substances tried we find common salt, sal ammoniac, acetates of
ammonia and potash, nitre, borax, alum, camphor, aloes, and succinic
acid. These experiments, which were conducted in a very systematic
manner, are even now not without some value. By taking as a
standard the antiseptic action of 60 grains of salt on 2 grains of
meat in 2 ounces of water, he was able to show that the other bodies
enumerated above had a greater antiseptic power than this standard,
and thus succeeded in arriving at their relative antiseptic value.
Bacteriology. — Even the pioneers of modern chemistry at the begin-
ning of the present century, did little towards promoting our knowledge
of disinfectants, and it was not until the biologist showed that decay
was due to the action of living organisms which float in the air, that
fresh attention was directed to the subject, Francesco Redi, by pro-
tecting meat from flies with wire gauze, showed that the maggots
which infest decaying flesh were produced from the eggs of the flies.
Subsequently the formation of moulds on the surface of jams, or other
organic substances, was similarly shown to be determined by micro-
4 DISINFECTION' AND DISINFECTANTS.
organisms floating in the air. It was further noticed that infectious
diseases spread more rapidly in damp warm weather when there is
very little wind, and that filtration of the air through cotton wool was
effectual, not only in removing the dust, but also in preventing the
ingress of micro-organisms.
The gradual accumulation of such facts as these by the biologists led
the chemists to realise that the removal of the odour was not, after
all, the only work required to be done, and the use of fumigations
with nitrous acid, hydrochloric acid, and chlorine and other j)ungent
bodies, which had been recommended, fell gradually into disfavour.
Pasteur's work, together with the general development of the
modern science of bacteriology, has given to chemists a means of
ascertaining the relative value of the various chemical substances dis-
covered from time to time. It was to Pasteur's careful investigations
that the close analogy which exists between fermentation and putre-
faction was established. Pasteur himself defined putrefaction as
" fermentation without oxygen," and showed that all decay was due
to the action of organisms, the Bacterium termo being the common
organism which begins eremacausis.
Owing to the slight knowledge which we possess as yet of the
nature of the pabulum in which these bacteria of decay live, the
investigation of the way in which they act is a matter of great
difficulty. In recent years, however, the life -history of known
organisms has been carefully studied, and the chemical changes which
are produced when they live in media of known compositions have
been followed. Thus organisms have been allowed to grow in solu-
tions of calcium formate and calcium acetate, both of which substances
have a definite chemical constitution. The bacteria decompose these
salts, evolving carbonic acid gas, mixed with hydrogen in the former
solution, and carbonic acid, mixed with marsh gas in the latter.
Lactic acid and its salts, butyric acid and its compounds, as well as
other chemical substances of known constitution, have also in recent
years been examined bacteriologically. From studies such as these
it seems to be clearly established that, just in the same way as the
yeast when it converts sugar into alcohol is killed by the alcohol it-
produces, so these other micro-organisms secrete chemical compounds
which are inimical to their own life. In the decomposition of animal
matter containing nitrogen, compounds which are soluble in weak
alkaline solutions, and known as alkali albumens, are first ])roduced,
and these subsequently change into albumoses and peptones, to be
again broken down into tyrosine, indol, and other compounds. These
latter have strong antiseptic properties, and illustrate the fact already
alluded to — viz., that the products of decomposition are iu the
IXXrODUCTORY. ,
majority of cases themselves inimical to the bacteria which give rise
to them.
The Methods of dealing with Bacteria.— The ideal of disinfection
is to stamp out the pathogenic bacteria, just as weeds are extirpated
from a garden. This can never be done until their hotbeds, the filthy
slums of cities and the neglected country villages, are cleansed and
supplied with plenty of good water, and, in the cities, with air and,
above all, light. Every dirty court or alley is an admirable culture-
medium in which disease organisms may multiply ; these issuing in
a variety of ways, as by clothes, food, and even sometimes by the
atmosphere, may unexpectedly decimate the so-called better neighbour-
hoods. There is no reason why infectious disease of all kinds should
not be entirely abolished ; but it can only be done when the entire
population is supplied with knowledge, and placed under conditions
in which health is possible. At present it is indispensable that
measures of precaution should be taken continually and habitually to
prevent any outbreak rather than, as too often is the case, only
spasmodically when a plague like cholera threatens. The success of
improved sanitation in rendering obsolete in modern Europe such
plagues as carried off millions at intervals in the Middle Ages, shows
that the abolition of infectious disease is possible, but we have
still among us " that sad disgrace, our customary (and preventable)
autumnal epidemic of scarlatina." This would certainly yield to a
vigorous and systematic insistance upon isolation and application of
disinfectants. With reference to the first precaution, more and better
accommodation will have to be provided. As to the second, one great
reason of the want of progress has been the fact, that many of the
modes pf disinfection, even those prescribed by high authorities, are
absolutely inefficient and useless. We must get rid, to begin with, of
the idea that the creation of a rival smell is any criterion of safety ;
we must cease to be misled by laudatory advertisements, and anti-
quated opinions founded on inaccurate experiments before bacteriology
became a science, and we must not grudge the expense of a sufficient
quantity and a proper application of the disinfectants that have been
proved scientifically to really effect their purpose. The problem then
resolves itself into a struggle for existence between man and inimical
micro-organisms, which are known to have great vitality, powers of
endurance, and facilities for penetration, accompanied by a stupendous
fecundity. The means at present at our disposal for dealing with this
problem can be classed under three heads : —
1. Exclnsion. — The rough methods of quarantine and sanitary
cordons have not proved a success, since the ways of ingress are so
many and wide, and the intolerable oppressiveness of these regulations
DISINFECTION AND DISINFECTANTS.
leads certainly to their frequent evasion. The English methods of
inspection, and temporary closure of certain routes, have proved much
more effectual. The last, or personal, line of defence lies in the care
and precautions taken by the individual. Most of these are indicated
in Chap. XIII., "On Personal and Internal Disinfection." Cleanliness,
fresh air, light, and good water are the chief
In recent years it has also been shown that many, if not all, zymotic
diseases may be excluded from the ])erson by the introduction of
.special toxines into the individual, a process which renders him
immune from the attacks of the organisms that produce the disease.
These toxines are produced by the pathogenic organisms themselves,
and, as already mentioned, are usually inimical to the growth of the
organism, and may be regarded as their natural disinfectants. In
view of these facts, Pasteur and his successors have cultivated the
pathogenic organisms in broth and other media, and after sterilisation
have injected the liqiiid products as prophylactics against various
diseases. The virus can also be attenuated by passing it through
different animals, or by special methods of taming, until, whilst still
producing the toxines, it can be introduced into man without pro-
ducing any dangerous symptoms, and thus can render him immune
from fresh attacks, or place him in a position to develop the natural
disinfectant sufficiently rapidly to kill off the pathogenic organisms,
even after they have gained access to the blood. Dr. Roux, for
example, at the Vienna Congress in 1894, reported a large number of
cures of diphtheria by injecting a quantity of serum from the veins of
a horse previously inoculated with Lo^ffler's diphtheria bacillus. Under
the name of antitoxine, this diphtheria antidote is now a commercial
article, and may be regarded as a special disinfectant for dealing with
the organisms of this disease.
2. Removal. — Under this heading may be included the natural pro-
cesses which obtain in a healthy individual, and artificial methods for
improving his environment. It is now well established that the blood
by its white corpuscles, as "phagocytes," or by its enzymes, has the
power of assimilating and destroying bacteria and spores that find
their way into it. If vigorous health be maintained, experience proves
that a human being or animal may enjoy immunity for a time, even
when in an infectious area. The limit to this protection may be reached
when the micro-organisms overcome the phagocytes or other defensive
substances in the blood. Many natural processes, external to the indi-
vidual, such as the self-purification of rivers, aid the higher organisms
in this combat. Man, by artificial methods of subsidence, mechanical
precipitation by inert matters, filtration, and chemical precipitation,
supplements these efforts of nature to purify the water supplies.
MECHANICAL DISINFECTION. 7
3. Destruction. — This is the office of real disinfectants, of which the
physical agent heat is the most important. Next come the multitude
of chemical disinfectants, many of which have been highly vaunted,
but few of which are of actual value. A knowledge of the chemical
constitution and relative position of these compounds throws con-
siderable light on their mode of action ; and recent progress in
synthetical organic chemistry has been of great aid in furnishing
compounds of known purity and constitution, which have, at the hands
of the bacteriologist, been shown to possess antiseptic and disinfectant
properties of ascertained value. The number of these compounds is
constantly on the increase, but at present it is difficult to predict,
except in some few special cases, in what direction the constitution of
a compound influences its bactericidal behaviour. It seems probable,
however, that the several pathogenic organisms will be best annihilated
by specific chemical compounds, so that, for personal disinfection at
any rate, some of the newer compounds may eventually be proved to
be definite specifics.
CHAPTER II.
MECHANICAL DISINFECTION.
Insufficiency of Deodorisation — Physical Means — Light capable of killing Bacteria
— Sunlight and ordinary Daylight— Conclusions — Inert Substances : Carbon
— Animal Charcoal — Vegetable Charcoal — Disinfection Gratings — Use in
Closets — Peat Charcoal — Coke — Soot — Coal - dust — Peat — Sawdust — Clay —
Dried Earth — Spongy Iron — Infusorial Earth or Kieselguhr — Ashes and
Cinders — Gypsum — Sand Filtration : Conditions of its Efficiency— Chamber-
land and Berkefeld Filters — Stone Filters — Purification of River Water :
Clark's Method — Gaillet and Huet's Process — Natural Purification — Desicca-
tion : Resistance of Microbes to Drying.
Insufficiency of Deodorisation. — The simple removal of smell, or even
the act of disguising it by a chemical of more powerful odour, is
frequently looked upon as disinfection. Yet it is obvious that the
removal of the injurious products of putrefaction, although it may be
of temporary benefit, will not prevent the organisms from reproducing
a further quantity. There are also a number of micro-organisms
known, in whose growth there is never any ill smell evolved, and no
ammonia or sulphuretted hydrogen detected ; but which, at the same
time, form ptomaines, and are in other ways dangerous to health.
Some of these, as pointed out by Klein, may evolve an aromatic smell
and thus be tolerated.
"8 DlSINFECrriON AND DISINFECTANTS.
Light as a Disinfectant. — In those cases in which it is advisable that
large volumes and surfaces should' be sterilised, it is not usuallj
practicable to kill all the bacteria by chemical agents ; therefore
recourse must be had to their removal by physical means.
LIGHT.
The action of light is one of the most important of these physical
agencies for diminishing the number of microbes.
Downes and Blunt* first demonstrated the antagonistic action of
light towards bacteria. Test tubes containing sterilised Pasteur
solutions were exposed to intermittent sunlight and diffused daylight
for periods varying from days to months, having been previously
infected by minute quantities of liquids containing bacteria, or else
exposed for a time to ordinary air. A similar set of tubes were
covered completely with tin-foil to exclude light, other conditions
being the same. They found that direct sunlight in some cases
entirely prevented the development of the organisms, in others only
retarded it, and that even diffused daylight had a distinctly deterrent)
effect. The blue and violet rays of the spectrum were much more
active than the red and. orange. They further showed that the
influence on spores was not exerted in a vacuum, that the nutritive
value of the culture liquids was not afiected, and that the bacteria
were much more resistant when immersed in water than when sur-
rounded by any other medium. From these facts they attributed the
destructive effect of light to the promotion of oxidation by the influence
of the sun's rays — i.e., to the so-called actinism of light. (See Chapter
xiii. as to the influence of light on the rancidity of butter.)
A number of other investigators continued the research with pure
cultivations of pathogenic bacteria, and particularly on the production
of colours by the pigment-producing bacteria. It was noticed that the
sun's rays appeared to favour the development of several kinds of yeast
and moulds, and that the action of light was increased by the presence
of air.f Pansini % found that the destruction was rapid during the
first period of exposure, 360 colonies of B. anthracis being reduced in
half an hour to 4, but that the further operation proceeded much
more slowly. The spores of anthrax in a dry state were more
resistant to light than when moist ; in the latter case an exposure of
from thirty minutes to two hours was sufficient to destroy them,
♦ Proc. Roy. Soc, Dec. 6, 1877.
+ Arloing and Gaillard, Influence de la Lumiere sur lea Micro-org., Lyon, 1888 j
Uffebnann, Hyg. Bedeiit. des Sonnenlichtes, 1889.
X Rivista d'Igiene, 1889.
MECHANICAL DISINFECTION. 9
Koch says that sunlight, or even ordinary daylight, will kill tubercle
bacilli in from a few minutes to five or seven days, according to the
thickness of the sti-atum.* Janowski has also prove<l that four to ten
hours' sunlight destroyed typhoid bacilli. After passing through a
solution of potassium bichromate, so as to cut off the blue and violet
portions of the spectrum, the rays had no effect, t He showed also
that the effect of the light was not due to increase of temperature.
Geister demonstrated that an electric light of 1,000 candle j)Ower at
1 metre distance was less effective than direct sunlight.:}: Marshal)
Ward§ showed that the dried spores of anthrax were acted on by
light in the absence of food materials, and that the light did not
appreciably diminish the nutritive value of the agar-agar medium.
Khmeleosky finds that both solar and electric light inhibit the growth
of Staphylococcvs jyyogenes aureus, Bacillus pyocyane^is, Streptococcus
erisiptelas, and .S'. jyyogenes. Sunlight destroys their vitality in about
six hours, and exposure to sunlight seems to mitigate their virulence
when it does not destroy them. It also makes the media less f ivour-
able to their growth. || Percy Frankland and other investigators
have examined the action of light on the organisms in the Thame*
and other waters.U Buchner has also shown that in water typhoid
and other cultures are destroyed by exposure to bright sunlight for
three hours. By immersing cultures to* different depths in the
Sternberger Lake at Munich he has further demonstrated that the
;t(ericidal action does not extend to a greater depth than three yards,
an3 that hence in the self-purification of rivers the action from this>
cause is chiefly superficial. The conclusions of the various researches
may be summarised to the following effect : —
1. Light has a deleterious action on bacteria in their vegetative,
and, to a less extent, in their spore forms.
2. The action is not caused by the rise of temperature. The ultra-
violet rays are the most powerful, and the infra-red the least, showing
that the phenomenon is due to chemical action.
3. The effect is greatly increased by the presence of air and
moisture, so much fo that it is undoubtedly due to a process of
oxidation, possibly brought about by the agency of ozone or peroxide
of hydrogen, or both. This view is supported by experiments by
Richardson,** in which it is shown that peroxide of hydrogen is formed
in urine dui'ing insolation, and that the sterilising action of light can
be counteracted by the addition of substances — e.g., peroxide of
* Zeitschrift filr Hygiene, vol. x., p. 285.
t CentrcUhlatt f. Balteriol, 1890, pp. 1(J7, &c. X Ibid., 1892, vol. xi., p. 161.
§ Proc. Roy. Soc., 1893, p. 310. II Brit. Med. Joum., 1894, p. 72.
IT Ibid., 1893, p. 20. *• Proc. Chem. Soc, 1893, p. 121.
10 DISINFECTION AND DISINFECTANTS.
manganese — which destroy liydrogen peroxide.* Richardson shows
that the insolation of water alone' does not generate peroxide of
hydrogen. Dr. Frankland thinks that in the case of dried bacteria, or
those suspended in pure water, the destruction is occasioned by the
peroxide formed within their cells.
4. The action is not generally due to any alteration of the medium
by light.
5. The result varies according to the duration of the exposure, the
intensity of the light, and the nature of the organism. Anthrax
spores grown at 38° C are much more easily killed by light than those
obtained from the same source at 18° to 20° C.
6. There is no evidence that the virulence of anthrax undergoes any
permanent attenuation through exposure to light.
7. Anthrax spores are less rapidly destroyed in distilled or potable
waters than in culture media, or in an isolated condition. Their
-endurance is particularly long-continued in distilled water in absence
of air, resistance to upwards of 110 hours' exposure having been
observed by Momont.f The addition of a halogen salt, such as
sodium chloride, materially increases the rapidity of destruction, while
an oxy-salt, like sodium sulphate, has little or no influence.
8. The efi"ect is much diminished by the rays passing through deep
layers of water.
9. Wliilst every opportunity should be afforded for insolation in the
•construction of water woiks, undue reliance must not be placed on
this any more than on any other particular bactericidal agency {Percjf
Franhland).
Professor Esmarch has endeavoured to make use of sunlight as a
practical disinfectant for skins and furs which cannot be sterilised in a
steam disinfector. He finds, however, that, as might be expected, the
light has only a surface action, especially on dark materials, and that
it is, therefore, valueless when micro-organisms are likely to be present
in the deeper parts.
MECHANICAL PURIFICATION OF GASES AND LIQUIDS.
Inert substances have been used (1) for the removal of bacteria by
mechanical straining or precipitation, (2) for the absorption of noxious
emanations.
Carbon. — Animal charcoal, or bone-black, more particularly absorbs
substances in solution (see Filtration, p. 15). When thrown into
sewage, especially with clay and other heavy powders, it carries down
with it almost the whole of the suspended matters into the sludge, and
* P. FranklanJ, Micro-ortjaniamH in Water, 1894, p. 389.
t Ann. de I'ln.'-t. Pasteur, 1892, vol. vi , p. 21..
MECHANICAL DISINFECTION. 11
also removes sulphuretted hydrogen, ammonia, the ptomaines, and the
greater part of the other organic compounds, so as to leave the
supernatant liquid nearly colourless and clear. If it could be used in
sufficient quantity it would be one of the best of purifiers. It also
effects a slow oxidation of the matters contained in the deposit, by
means of the oxygen which most forms of carbon absorb from the air.
Unfortunately, it is an expensive material, as bones are in great
demand for manure. A large number of processes, many patented,
have endeavoured to recover the phosphate by using the sludge as a
fertiliser, but they have all, so fai', met with little commercial success.
Vegetable cliarcoal has a still greater power of condensing gases
within its pores. One volume of wood charcoal will absorb the
following volumes of different gases : — Ammonia 90, sulphurous acid
€5, sulphuretted hydrogen 55, carbon dioxide 35, carbon monoxide
9*42, oxygen 9 •25. Those gases and organic vapours which are capable
of oxidation, and possibly bacteria, are destroyed when they come in
intimate contact, within the pores of the charcoal, with the oxygen
derived from the air. The charcoal should be freshly prepared, or
should be reheated to a temperature short of ignition, as it rapidly
loses in power. By the latter means, or, better, by charring again in
closed vessels, it can be re-vivified many times. Charcoal derived from
different woods has slightly varying powers of absorption ; as a general
rule, the more porous it is the greater the activity. Vegetable charcoal
has less action on liquids than animal, and being lighter than water
floats on the surface. Letheby, Stenhouse, and others proposed the
use of gratings containing wood charcoal as ventilators for buildings
and sewers. They did not, however, prove a success, as they soon
become exhausted. If the dead body of an animal be buried in
wood charcoal it decays without putrefactive odour, except that
ammonia is evolved. "Wood charcoal removes the odour of all
decaying matter, and has been largely employed to restore tainted
meat, by placing it in the water used for boiling. Although the taint
is removed, the food is not thereby rendered wholesome. It may,
however, be usefully employed when only a slight change has occurred.
Revill * demonstrated that charcoal is not, in a true sense, an anti-
septic, since it rather hastens the decomposition of putrescible matters,
although, by absorbing the products, it renders the process inodorous
— i.e., it is simply a deodorant. Still it has considerable value for
cess-pools, water-closets, and dead bodies, when a removal is necessary.
Goddard tfe Co. in 1887 patented an automatic purifying closet in
which a mixture of animal and wood-charcoal, under the name of
"Sanitary Carbon,'' was discharged mechanically on the excreta at
* Archives g6nir. de Mtd., 1833.
12 DISINFECTION AND DISINFECTANTS.
each discharge. It was said to effectually deodorise the excreta, which
is true, and by retaining the ammon'ia, to produce a manure of some
value. On shutting down the lid a sufficient quantity of the carbon
is scattered over the excreta in the pan beneath at a cost for each
time of using of one-eighth of a penny.* In all these methods of
using carbon it is found that, as the ammonia is rather rapidly evolved
on exposure to air, the substance soon becomes almost devoid of
nitrogen, and has practically no value as a manure.
Peat-charcoal is very light and absorbent. Its application has not
been a success owing to its friability. Powdered coke, being denser,
possesses much less power, yet it has been j)roposed in many patents
for purifying sewage, either alone, or as an adjunct to other agents.
As an instance, Kingzett in 1887 patented the use of a mixture of
powdered coke and dry clay as a sewage precipitant. He states that
the deposit can be readily pressed.
Coke alone has only a mechanical action.
Soot contains empyreumatic and bituminous matters in small quan-
tity, and has therefore antiseptic properties due to these ingredients,
but its power, though rather lasting, is not very great. It is moder-
ately absorbent. In horticulture it is much used as an insecticide.
Sprinkled about sewers and drains it removes the odour.
Coal-dust, being scarcely porous, is almost inert. Natural bitumens
have long been used for embalming, but a great part of their effect is
due to the mechanical exclusion of microbes. M. de Mily has recently
carried out a number of experiments on the use of bitumens mixed
with chopped rags (100 kilos, of rags to 10 of bitumen for 600 vines),
to prevent the attacks of Phylloxera and other pests on ground that
could not be treated with sulphur. The bituminous earth from
Rhodes, which was mentioned by Strabo in GO B.C., has also been
recently used for this purpose. The results seem to have been most
satisfactory.
Peat itself when dried is of value for absorbing moisture and, with it,
noxious emanations. 1 lb. of it (containing 25 per cent, of water) can
take up seven and a-half times its weight. 100 lbs. of powdered peat
will absorb 1,438 litres of ammonia. Several i)atents have been taken
out for incorporating it with disinfectants, for which ptirpose it seems
at first to be admirably suited for use in stables, Jic. Ernst f proposes
that peat or moss should be mixed with 2.^ per cent, of iron sulphate
or phenol, and used for litter, privies, &c.J The odour of stables in
which peat moss is employed is less than those in which straw is used
as litter ; on the other hand, powdered peat is now somewhat exten-
-* Lancet, 1887, p. 886. t Patent No. 2,581, 1882.
:;: Westknight and Gall, Patent No. 11,011, 1886.
MECHANICAL DI8INFECTI0X. 13
sively used for dry closets, and has the advantage over earth of
absorbing the urine. Schroder has also shown that it has a true
disinfectant action on cholera vibrios, although other pathogenic
organisms are more resistant. Drs. Frankel and Klipskin * have
investigated the subject more minutely and have established the fact
that the comma bacillus when mixed with peat-dust is destroyed in
about three hours, whilst cholera vibrios may retain their vitality for
fourteen days, unless the iirine be acid. Dempster t has shown that
the cholera bacillus cannot live in peaty soil. The addition of super-
phosphate augments the disinfecting action of the peat, whilst kainite
has little influence. The authors, therefore, strongly recommend the
use of peat for isolated dry closets.
Sawdust, especially the varieties derived from pine wood, is widely
used, on account of the resinous and aromatic compounds it contains,
which seem to ozonise the air to some extent, and also give off an
agreeable odour. It is not a good vehicle for disinfectants, as it is
not very absorbent, but is used to some extent in country districts
where there is no water supply for retaining urine in urinals.
Clay, blast furnace slag, sbale, and dried earth are all used for
special purposes.
Infusorial earth, or Kieselguhr, sterilised by being subjected to a
heat sufficient to cause it to glow, is said by Dr. Habart to be excellent
as a dusting powder in surgery. It absorbs from five to seven times
its weight of water. Mixtures of equal parts of the earth and
salicylic acid, salol, or iodoform, as well as a 1 in 2,000 trituration of
corrosive sublimate, have proved useful.
Ashes and Cinders. — In Belgium and Holland the household ashes
are thrown daily into privies and ditches with the idea of disinfection.
In Salford, Oldham, and other places, the ashes, vegetable, and street
refuse were formerly carbonised and used for the same purpose, some-
times with the addition of charcoal and dry earth, as recommended
by Parkes. But though the odour is in great part removed for the
time, and the excreta are solidified so as to facilitate removal, no
true disinfection is accomplished.
Gypsum with coal-tar, under the name of poudre de Come et
Desneatcx, was formerly much employed in France for disinfecting
wounds. J Gypsum is still sometimes used in stables. Asbestos, talc,
pumice, in fact any dry absorbent powder, will act nearly as well.§
• ZeiUch.f. Hygiene, 1893, p. 333.
t Brit. Med. Journ., May 26, 1S94.
t Valpeau, Gnmptes Rendua, 1860, p. 279.
§ Vallin, Du'mfectants, pp. 41, 56.
14 DISINFECTION AND DISINFECTANTS.
SAND FILTRATION.
Percy Frankland * states that out of 100 micro-organisms present in
untreated river water, there were removed by the Water Companies,
before distribution, in the case of the
1886. 1887. 1888.
Thames, 97-6 96-7 98*4
Lea (East London Co.), . . .96*5 95-3 95-3
Sand filtration carefully pursued offers a remarkable and obstinate
barrier to the passage of micro-organisms, and there is every justifica-
tion in presuming that if disease organisms are at any time present in
the raw untreated water they would be retained. This was proved by
experience in the cholera epidemic at Hamburg and Altona in 1892,t
when in Altona the water was filtered carefully, in Hamburg not.
Although the original water supplied to Altona was worse than that
of Hamburg, the deaths in Altona were 221, in Hamburg 1,250, per
100,000. At the end of 1892 an outbreak occurred in Altona owing
to a filter-bed breaking down, proving that the slightest imperfection
in the manipulation is a constant menace during any epidemic.
Frankel and Piefke studied the rate of filtration, J and came to the
following conclusions : —
1. A filter running rapidly soon clogged, and did not properly
remove bacteria.
2. The full eff'ect was not obtained until the filter had been at least
a day in use.
3. High pressure is inimical to efliciency.
4. The quicker filter actually passed less water in the course of the
month than one which was originally slower, owing to the former
becoming clogged.
5. Cholera and typhoid were not completely stopped, but the former
organisms were more removed than the latter.
6. The slime that forms in the upper layers is the main agent in
entanfflinsr the bacteria. Sterilised sand did not retain the microbes.
7. The efl3.ciency was in all cases only relative, not absolute. Thus,
mixed coarse and fine sand with fine gravel, of a depth of 3 feet
8 inches, removed 74 per cent.; fine sand, 5 feet deep, 86 per cent.,
and garden earth and peat retained nearly all the micro-organisms,
but the latter two in practice were too slow § to be of any practical
value as filtering media.
Mechanical filtration for domestic purposes can be effected by the
* Micro-organisms in Water, 1894, p. 124; also Trans. San. Inst. G. B., vol.
viii., 1886.
t Koch, Ze.it. f. Hyrj., vol. xiv., p. 393 ; vol. xv., p. 89.
:;: Zeit.f. Ilyrj., 1890, vol. viii., p. 1.
§ Report of Massachmetls Board of Health on Purification of Sewage, 1890-93.
MECHANICAL DISINFECTION. 15
Chamberland filter, or by the Berkefekl modification. The former
consists of a cylinder of biscuit or unglazed porcelain. The latter is
made of compressed and baked infusorial earth ; to renew it, it is
cleansed under running water, put into cold water, which is then
raised to boiling, and boiled for some time. It is quicker than the
Chamberland and possibly equally efficacious. If a few litres are run
to waste, and it be kept in a cool place, and washed and sterilised every
eight days, no bacteria will find their way through the material.*
Stone filters are absolutely unreliable.! Asbestos does not long
continue to retain micro-organisms, J and Drs. Sims Woodhead and
Cartright Wood, in a recent report, have shown that, with the excep-
tion of the filters already mentioned, there are none which are of real
value. The number of bacteria per cubic centimetre (as counted
under the microscope) has become one of the chief elements in valuing^
the merit of a water. Spring waters have superseded river waters,
and towns, Avhich have hitherto sought water from their own rivers,,
have had to seek other sources of greater bacterial purity. The
principal processes of purification are : — (1) Deposition, either natural
or assisted by the addition of precipitants ; (2) oxidation; (3) the vital
actions of the microbes, in which "the last word belongs to the
aerobic, and, therefore, to the most inoffensive." §
Clark's well-known method of softening water by the addition of
slaked lime to a water, whereby nearly the whole of the carbonate of
lime is precipitated, has long been known, not only to soften the water,.
but also to carry down the greater part of the colouring matter and
suspended impurities, mineral, organic, and living. Thus at Hampton,
it has been found to reduce the germs in the Thames water from
1,437 per c.c. to 177.
Other Methods. — Among modifications of Clark's expired patent are
Gaillet and Huet's, which consists in the addition of caustic soda and
accelerating the separation of calcium carbonate by deposition between
plates, and Maignen's Anticalcaire, which contains more sodii, sodium
carbonate, and lime, and throws down nearly all the lime and magnesia,
of the water.
Percy Frankland, in a compai'ison of the original Clark's process
with that of Gaillet and Huet, as tried on the water of the Colne
Valley Waterworks, found
Clark, after two daj's subsequent rest, .
Gaillet and Huet, after two hours,
* Zeitschr. f. Hyj., 1891, vol. x., pp. 145, IflS ; Freudenreich, Centr. f.
BakterioL, 1892, p. 240. .i> Esmarch, xhitL, 1892, vol. xi., p. S25.
J Jolles, ibid., 1892, vol. xii., p. 59C. § Duclaux, Ann. de VInst. Pasteur, 1894.
Qerms
before.
.322
Germs
after.
4
Reduction
per cent.
99
182
4
98
16 DISINFECTION AND DISINFECTANTS.
SO that the addition of soda very greatly increases the rapidity. It
must be borne in mind that even if only 2 per cent, of the organisms
are left the water is not sterilised, "but the subsequent addition of a
relatively small quantity of a chemical disinfectant would secure such
a result.* Slow deposition alone diminishes the number of micro-
organisms present in a liquid. In the passage through two settling
reservoirs of the New River Co., Dr. P. Frankland found that the
alteration in the number of germs present was as follows : —
Germs per c.c.
Entrance of first reservoir, .... 677
Exit ,, .... 560
,, of second reservoir (large one), . . . 183
Reduction only 27 per cent.
Buchnert introduced into clean water in repose a number of
•difterent micro-organisms. £. jjyocyaneus multiplied abundantly, but
B. typhi and B. coli (the ordinary bacillus of the intestines) died in
two or three days,; whilst Percy Frankland in Thames water, and
J. Parry Lawes in London sewers have noticed similar results.
Duclaux concludes by affirming that putrefaction itself jnirifies, and
the microbes themselves are the chief purifying agents. It is true
that although they finally convert putrefying matter into carbonic
acid, ammonia, nitrates, and water, which are harmless, in the process
several transition products are formed which are very poisonous.
Moreover, if they multiply witliin the body they produce disease by
mechanical irritation, by starving the nutrition, or by excreting toxic
compounds, such as ptomaines, Ac, into the blood. It is necessary,
therefore, (1) to keep their numbers within bounds, (2) to exclude or
kill the specially dangerous ones, (3) in special cases, as in preservation
of food, to get rid of them altogether. Such an end can be attained
in the case of sewage effluents, first by accelerated deposition, second
by chemical disinfection of the clarified water, and, finally, by subse-
quent irrigation and filtration through land.§
Scott Moncriefi" has recently proposed to utilise the micro-organisms
of putrefaction for destroying the sewage itself, and has patented the
use of special cultivation beds for this purpose. The process has been
successfully worked at Towcester, and has been tried at Aylesbury.
DESICCATION.
It is well known tliat hot warm climates are the special seats of
diseases of an epidemic character, and that dry localities, whether cold
or hot, are comparatively healthy. Moisture and warmth being
* See also Kruger, Ann. de VInst. Pasteur, vol. ii , p. 621.
■f Archiv. f. Uyjiene, 1892, p. 184. +See also Schmidt, ih'.d., vol. xiii., p. 247.
5 Miquel, Analyne Bactiriol. den t'artx, Paris, 1891, p. 139.
MECHANICAL DISINFECTION. 17
fevourable to the growth of micro-organisms, it might be supposed
that cold and dryness would prejudice their vitality. To a great
extent this is the case. In 1871, Burdon Sanderson showed that ice-
water from the purest ice contained bacteria.* lanowski proved that
snow even at - 3-9 to — 16" C. contained living micro-organisms,t
Schmelk found the same in snow from a glacier in Norway, J Fraenkel
in ice supplied from a lake near Berlin. § Pictet has also shown that
the temperature of liquid air had no germicidal action. It has thus
been shown that cold alone will not kill many bacteria ; it remains to
see how far desiccation is effectual against them. In sandy deserts
it is common to find corpses dried and free from putrescence ; food
can also be dried, and if kept protected may be preserved for an
unlimited time. Herbs and vegetables are thus desiccated and ren-
dered free from fermentation. Some plants, even when dried, revive
when they come to a moist spot, and there are well authenticated
cases of mummy wheat having germinated. Desiccation thus seems
to suspend the vitality of seeds, and not to destroy it. This is true
for germs ; when perfectly dry they remain for the time sterile and
inoffensive, and seeiTi to be subject to aei'ial oxidation ; but if, by the
winds, or other agencies, they are carried in time to a moist situation,
like a body of water, a plant, a human skin, or, still better, a mucous
membrane (such as that of the lungs), they at once revive and com-
mence to develop.
The utility of the Eucalyptus and other trees in marshy districts is
partly due to their absorbing and exhaling the moisture of the soil.
Siccative powders, like starch and steatite, are known to be useful in
surgery. Many epidemics have suddenly ceased when a dry season
has set in.
Both Koch and Klein have proved that the spores of most of the
common species of bacteria resist drying for an indefinite period.
Klein kept the spores of various potato bacilli — e.g., Peronospora
infestans (the potato blight). Bacillus anthracis, the hay bacillus, and
those of scurf and jequirity, in culture tubes of agar agar in a per-
fectly dry state —i.e., in a closed bell-jar over oil of vitriol — until the
medium had dried up to a thin shrivelled film ; and yet, even after
two years and a half, on inoculating fresh materials from the above
tubes, typical and good growths were obtained. On the other hand,
non-spore-bearing bacteria — e.g., various species of Staphylococcus,
Streptococcus — bacilli of typhoid, swine fever, swine erysipelas, Koch's
* Thirteenth Be port of Med. Off. of Privy Council.
fCentr.f. Bakteriologie, 1888, vol. iv., p. 547. :J/6Jd., p. 547.
%Ze\tachr. f. Hyg., 1886, I., p. 302. See also Heyroth, Arbeit. Kais. Oeaund.,
vol. iv., 1888.
2
18 DISINFECTION AND DISINFECTANTS.
and Finkler's bacilli, bacilli of pneumonia, fowl enteritis, chicken
cholera and grouse disease, as well as a number of others, Avere kept
as agar cultures until the latter had well dried up. No sub-cultures
could be raised from any of them. In other experiments tliey were
dried in a current of air, or by simple exposure in a thin film on
cover glasses in the manner employed by Koch, leaving them pro-
tected from dust till dry. No growth of the non-sporiferous species
could be obtained in gelatine. If the drying is not complete, that is
if the film be too thick, so that the superficial layer forms a protective
coating for the rest, then the result of inoculation with such material
will be positive ; the bacteria below the surface, having been protected
against drying, survive, and can produce a new crop. Similarly, when
particles of solids containing bacteria are dried, it will be found that
here also the centre escapes thorough drying, being protected by a
superficial crust. Ordinary dust particles, however small, are never
so dry that the bacteria contained in them are killed. The proof of
this is that numbers of non-spore-bearing bacilli and micrococci can
be cultivated from the dust of an ordinary room.*
Dempster has joointed out that cholera vibrio?, whilst they can
survive in moist soil, quickly die when the land is dry.t
Dr. Buchner J says that in the dust of a room B. tuberculosis has
been found alive a year after the patient died. But he does not
believe that the virus of typhoid or other fevers ever enters the human
body through the respiratory tract.
Provisions that have been smoked and dried may yet contain, nob
only micro-organisms, but also the ova of Trichina and worms.
Pemmican, the dried and powdered beef of the prairies, has been
said to communicate disease. If the meat, however, has been
thoroughly soaked in a preservative like pyroligneous acid, and then
dried, it is usually free from danger [Koch). Dry heat and superheated
steam as disinfectants will be further considered in detail in a subse-
quent Chapter.
* Klein, Stevenson, and Murphy's Hygiene, 1893, pp. 11, 81.
t Brit. Med. Journ., March 26, 1894.
X Ohio San. Record, April, 1894.
DISlNFEtrriON BY HEAT. 19
CHAPTER III.
DISINFECTION BY HEAT.
Heat as a Disinfectant : Conditions required in a Disinfector — Modes of dealing
with Condensation on Goods— Time and Steam Condition required for Dis-
infection — Experiments on the Penetrating Power of Steam — Types of
Disinfectors : English, French, Danish, German, American— Public Installa-
tions, English and American.
Heat as a Disinfectant. — It has been found in practice that there are
cases in which chemical disinfection is not suitable, owing to the
fact that many chemical disinfectants are very apt to cause damage to
the articles treated, and also that their action frequently involves pro-
longed exposure, and is even then only superficial in its effect. For
instance, the usual mode of disinfecting a room which has been occupied
by a person suffering from an infectious disease, is to close all outlets
and burn a given weight of sulphur therein for a period of several
hours. But if this treatment be applied to such things as heavy
"woollen clothing its effect is practically 7iil, as may be readily shown
by a very simple test. It has been found that a bright shilling, when
exposed in a room subjected to fumigation by sulphurous acid, is
immediately tarnished, but a similar coin wrapped up in a hand-
kerchief or placed in the pocket is not discoloured in the slightest.
It is fair to argue from this that, in the instance cited, the action of
the disinfecting gases has only been superficial. The chemical treat-
ment of the room is justifiable on the ground that in all probability
surface disinfection only is required in dealing with substances like
wood, bricks, and iron, it having been assumed that all permeable
articles, such as carpets, curtains, &c., have been previously removed
for more complete treatment. It is, however, open to doubt whether,
even in this case, chemical treatment would be resorted to were it
practicable to apjily disinfection by heat.
For the reasons that have just been stated it has become usual not
to attempt the disinfection of such articles as clothing, bedding, carpets,
«Skx, by chemical means, however invaluable such means have been
proved to be when applied to other cases. It would appear that
the inti*oduction of heat in some form or other for purifying purposes
would be an obvious step to take, but it must be remembered that
nearly two centuries ago, disease germs considered as organisms of
any kind, still less as bacteria-bearing spores, were then unknown,
20 DISINFECTION AND DISINFECTANTS.
and, if their existence had even been suspected, considerable experi-
mental proof would be required to show that a temperature below
that at which articles of clothing would be damaged or weakened in
their fibre, would be sufficient to destroy all danger of infection. The
work of Needham, therefore, during and before 1743, must be looked
upon with admiration, since it was he who first recorded experiments
in a systematic manner involving the use of heat with the object of
sterilising organic substances. His cultivations, as they would be
termed to-day, were placed in carefully-closed vessels surrounded by
fire, and his experiments led him to conclude that such treatment
rendered growth impossible. Curiously enough an after-growth in the
sterilised cultivating medium made him a convert to the theory of spon-
taneous generation, and it was in reference to this theory, the crucial
debate of the age among scientific men, that the publication of his
experiments was due.* Needham's great opponent, Spallanzani, in
reference to the same theory, also took up the question of sterilisation
by heat ; he even went so far as to detect the difference between dry
and moist heat, and showed that in some instances animal life was
impossible in water at 45° C, whereas the same cultivations were not
destroyed by dry heat at a temperature less than 80° C.
In 1804, Appert discovered that meat, vegetables, ic, when placed
in carefully sealed receptacles, and dipped in boiling water for an hour,
would keep indefinitely without putrefaction or fermentation. This
process was very carefully reported on by Gay Lussac (at the request
of the French Government), who, owing to these investigations,
expressed the opinion that no oxygen was present in the sealed vessels
after the process, and that the absence of this gas was essential to the
preservation of animal or vegetable tissue; but it was noteworthy that,
although this brochure was for long regarded as the standard work
dealing with the subject, no mention whatever was made of the
destruction of germ life within the vessel.
It is generally believed, however, that the earliest application of
heat to disinfection on a large scale, as opposed to the laboratory
experiments of Needham, Spallanzani, (fee, was not made public until
Dr. Henry, F.R.S., of Manchester, gave an account in the Philosophical
Magazine for 1831 of some experiments he had made on the disinfection
of infected clothing by hot air. A steam jacketted copper was used,
into the casing of which only steam at 212° F. was admitted; but,
apparently, it was found impossible to heat the interior to much more
than 200° F. with these appliances. Dr. Henry's results, so far as they
went, were encouraging, and tended to show that the clothing of
* See La giniration spontanAe, by I. Strauss ; Arch, de m6deciue expirimtntcUe,
t. 1", pp. 139-156 and 329-348.
DISINFECTION BY HEAT. 21
scarlet fever patients, which had been submitted to a temperature of
200° F. for two to four hours, would not propagate the disease if worn
by other healthy persons. Most of Dr. Henry's experiments, and
even of those of Dr. Baxter in 1875, were made with vaccine lymph,
and it was really not until the expei-iments of Pasteur, Lister, Burdon
Sanderson, Tyndall, and Koch had been published, that suflScient
data concerning the reality and nature of bacteria existed to render
it possible to test the efficacy of heat, dry or moist, as a destructive
agent.
The results of Tyndall's experiments (communicated to the Royal
Society in 1876 and 1877, and also contained in his well-known book,
entitled Floating Matter of the Air) were remarkable, inasmuch as they
treated the subject lai-gely from the physicist's standpoint. In this
work he proves conclusively how very variable is the treatment, both
as regards duration and intensity, of the heat essential for the
sterilisation of organic matter. He showed, for example, that hay
infusion might be kept continuously boiling for several hours and yet
not be sterilised, inasmuch as the spores could resist such treatment
and develop subsequently, although the original mature bacilli would
have all been destroyed. As a proof of this he boiled similar infusions
intermittently for a couple of minutes, twice or three times during a
day or so, and found that, although the total period of actual boiling
might be less than six minutes, compared with the hours of the
previous case, no aftergrowth whatever appeared in the prei)aration.
Tyndall also pointed out, and proved in some cases, that oxygen was
an essential to the existence of micro-organisms. He found that 180
minutes continuous boiling failed to sterilise a turnip infusion in the
presence of the ordinary supply of air, but that ten minutes at 212° F.
sufficed to produce absolute barrenness, when such heating was con-
ducted in absence of air. The production of a vacuum was found to
be such an important factor in sterilisation that experiments were
made to ascertain whether the total absence of oxygen would in itself
be sufficient to effect destruction, and in so many instances was this
found to be correct, that the conclusion was arrived at that, with suffi-
ciently perfect exhaustion, all infusions would probably be sterilised.*
The views of Tyndall, in reference to the necessity of oxygen for the
propagation of microbes, have since been much modified by the
experiments of later observers, who discovered that a small class of
bacteria, called " obligatory anaerobes," could only exist in the absence
of oxygen, and that others, " facultative anterobes," increased most in
the presence of free oxygen, although it was possible for them to exist
in the absence of this gas. The latter class is the larger of the two, and
• Comptes licndus, vol. Ixxx., p. 1579.
22 DISINFECTION AND DISINFECTANTS.
includes many pathogenic organisms, such as the Bacillus anthracis,
and the bacillus of Asiatic cholera. There is also a third class,
" obligatory serobes," to which the presence of oxygen is an absolute
necessity. The observations of I'yndall are, in this respect, not per-
fectly accurate, although it is probable that his conclusions would hold
true for the larger number of cases for which disinfection is required,
insomuch as clothing is constantly aerated, and, therefore, should,
under ordinary conditions, contain no living obligatory anaerobes.
The foregoing results are of the greatest importance from the prac-
tical standpoint, as will be seen later on. They paved the way for
further progress at the hands of Koch, Pasteur, and others.* Koch
made his experiments on ^jure cultivations of (1) non-spore-bearing
organisms, such as the Micrococcus prodigiosus ; and (2) of spore-
bearing kinds, such as anthrax bacilli, &c. He attempted disinfection
by chemical agency, hob dry air, and by steam ; moreover, in all these
cases the trials were eventually made on a sufficiently large scale, with
bedding, &c., to make his results of the greatest value. He confirmed,
generally, the result of previous workers that the spores were the
most difficult to destroy, and that, therefore, if they be devitalised,
all bacteria will also have been rendered harmless. In dealing with
hot air he found that spores were only destroyed by being exposed
at 284° F. for a period of three hours, but that at this temperature t
almost all fabrics which require disinfection are already injured,
a,nd that the rise in temperature inside a small roll of blankets so
exposed was not sufficient, unless the exposure was continued for a
much longer period. When steam at 212° F. was used as a disinfect-
ing agent, Koch found that anthrax spores, when freely exposed, were
killed in five minutes, and that even with steam at atmospheric pres-
sure, penetration of heat through blankets took place in about one-
quarter of the time necessary to secure a sufficient internal temperature
when hot air alone was used. From the medical point of view, these
experiments were most satisfactory, although, owing to the crude
nature of the apparatus used, it would appear that most, if not all,
the articles treated were considerably moistened and in some cases
damaged by the action of the steam.
Hoch and Wolf hiigel + conclude that " dry heat, even continued for
two hours at 150° C, did not always assure disinfection, although
nothing resisted, even for a few minutes, boiling water or steam at
100° C." Gaffky and Loffler§ summarise their experiments as
follows : —
* Mittheilungen aus dew. K. Ge^undheitsamte, vol. i., p. 188.
+ See also Brit. Med. Journ., September 6, 1873.
J Mitt. a. d. Kais. Gesundh., 1881, p. 301. § Ibid., p. 322.
DISINFECTI05 BY HEAT. 33
1. Non-spore-bearing bacteria cannot endure for one and a-half
houi-s an exposure to hot air at 100° C.
2. The spores of mould are not killed by one and a-half hours
exposure to hot air at 110° to 115° C.
3. The spores of bacilli are only killed by three hours exposure to
hot air at 140° C.
Bonhoff and Foster * state that Bacillus tuhercvlosis at 60° C. dies
in one hour, at 90° C. in five minutes, and at 95° C. in one minute.
The experiments of Dr. Klein and Dr. Parsons, as detailed in the
Annual Report to the Local Government Board for 1884, confirm very
largely those of Koch, and they also deal with the question of practical
disinfection in a manner that renders this work of very great value.
The great advantages of steam over hot air were demonstrated very
clearly, and, owing to the number and diversity of their experiments,
they were able to show that, in some cases at all events, the action of
steam in a suitable apparatus was not in itself injurious to the articles
treated.
The work of Pasteur, Tyndall, Lister, Koch, Parsons, and others
has, therefore, determined the fundamental conditions for successful
disinfection by heat.
Conditions required in a Disinfector. — It remains to be shown that
the mechanic can meet the requirements of the bacteriologists, and, at
the same time, deal with the practical difficulties that invariably beset
him during the introduction of novel machinery. The conditions for
dry-heat disinfection, so far as tempemture and duration of exposure
are concerned, have not been very clearly defined; but from experi-
ence gained by Dr. Hopwood at the London Fever Hospital, it may be
gathered that an exposure of bedding to hot air at a temperature of
250° F. for a period of nine hours is generally sufficient, and no
material damage is caused thereby to the goods.
The great difficulty in designing a stove to fulfil these conditions
arises from the fact that it is almost impossible to obtain a uniform
equable temperature in a sufficiently large chamber. It is probable
that exposure to air at a temperature of 260° F. for nine hours weakens
many woollen materials, and a temperature of 280° F. distinctly dis-
colours them, whereas an error of 10° or 20° F. on the lower side of
250° F. renders disinfection by these means more doubtful. The
allowable range of temperature in a hot-air disinfector should, there-
fore, not exceed 20° F., and the mean should be about 250° F., since,
according to Drs. Parsons and Klein, the free exposure of anthrax
spores to air at 245° F. for one hour suffices for their destruction.
Most engineers are well acquainted with the great difficulty met
• Hyj. Rinid*(hau, vol. ii. , p. 869.
24 DISINFECTION AND DISINFECTANTS.
with in heating air to a uniform temperature, and the problem is not
made any the easier by the fact that in such places where hot- air
machines are now required, steam is not available for heating the air.
If it were available, there can be "little doubt but that it would be
employed for the actual disinfection without the aid of air. As a
rule, coal and gas are the only sources of heat available for the pur-
pose, and even then, seeing that it is merely in the smallest and most
out of the way districts that hot-air disinfectors are permissible, the
first cost of the apparatus has to be kept so low that adequate tem-
perature regulating becomes almost impossible to provide for in a
chamber of the requisite size. It must be remembered that although
local conditions may make it excusable to erect hot-air apparatus, the
size of the hospital or population of a district does not determine the
capacity of the hot chamber, for it must be large enough to contair»
the largest article that it is likely to have to disinfect (usually a double
mattress) without being folded. In dealing with hot-air disinfection
it becomes especially important to arrange the articles in such a manner
as to reduce to a minimum the distance through which heat has to
penetrate, and, therefore, bulky things, such as mattresses, should
never be folded, and if several have to be treated at once, each should
be separated from its neighbour by wooden strips to allow of 2-inch or
3-inch air space.
Seeing that mattresses should not be folded, owing to the diminution
in penetrative effect of the heat, and frequently cannot be folded or
bent without damaging their construction, we can at once fix upon a
length of 6 feet as a minimum for the chamber, or if this be not
practicable, the diagonal should not be less than this, if, as is generally
possible in a hot-air chamber, a rectangular section can be used. One
dimension being fixed at 6 feet as a minimum, another may be deter-
mined in a similar manner by the width of the mattress. In hospitals
or public institutions beds do not commonly exceed 3 feet in width,
but private household mattresses very commonly exceed 5 feet. It
may, however, be assumed that in the future no 2^ublic hot-air dis-
infectors will be erected, and that their very limited scope will be
confined to small workhouses or institutions ; hence, after allowing for
a small margin, a depth of 4 feet should sufiice. The depth and length
being fixed respectively at 4 feet and 6 feet, the width may be fixed
according to circumstances depending on the number of mattresses or
clothes likely to require disinfection at one time. Thus four mattresses
each 6 inches thick would require a chamber 3 feet 6 inches wide, after
making sufficient provision for air space between each unit. As a
matter of fact the smallest really satisfactory hot-air disinfecting
chamber usually erected in this country is 4 feet 6 inches long, 4 feet
DISINFECTION BY HEAT. 25
6 inches high, 4 feet 6 inches wide internally, and in this an ordinary
3 feet X 6 feet mattress must be placed diagonally. This is a very
unsatisfactory arrangement, owing to the available space being so much
cut up, and also because the ends of the mattress rest actually in the
angles of the chamber where it has been ascertained a certain quantity
of "dead" air (i.e., unchanged or stationary air) generally remains at
a temperature considerably lower than the average throughout the
closet. The latter objection is in reality one common to most dis-
infectors of rectangular section, but if the chamber be of ample size,
these dead air spaces need not actually be occupied by portions of the
charge.
The question of air circulation through the chamber is probably one
of very great importance, for not only does it tend to promote
uniformity of temperature by admixture of gases of different tempera-
tures, but also it has been found that gases in motion can be more
readily heated by a hot surface owing to their rubbing action, and
conversely, that moving heated gases can part with their heat more
readily to cold surfaces than when they arc at rest. In all hot-air
stoves there is, of course, a certain risk of overheating the goods, and
in most cases they are temporarily weakened, and perhaps rendered
brittle, immediately after their removal, although these latter defects
usually disappear after the articles have regained their normal
hygrometric moisture; possibly this does not occur in such disinfectors
as have water pans exposed in the hot chambers. Precautions have
also to be taken to damp a tire in the chamber should it occur, owing
to the presence of lucifer matches, in spite of the fact that a careful
attendant can always search for and remove all sucli dangers from the
pockets and linings of garments, ikc. The danger against fire is very
usually guarded against by placing some fusible links in a chain
stretched across the interior of the chamber, which chain is so con-
nected to a damper that when broken, the latter closes the exit to the
chamber, and thus the fire is automatically gradually quenched through
lack of oxygen. The same device is also commonly geared to close the
gas sujjply, if it be a gas-heated machine ; but it must be noted the
arrangement is one which only comes into action after the evil has
arisen, and does not protect clothing from damage, but merely checks
the extension of fire. Dry-heat machines are likely to be little used
in the future, and it is, therefore, unnecessary to describe them at any
length. Dr. Parsons' Report of 1884 gives full particulars of the
several types then in use. Dr. Parsons found that very few, if any,
fulfilled all the conditions required for adequate disinfection, although
he mentions Bradford's apparatus as being the best coal-fired dis-
infector, and the invention of Dr. Ransom as being a very suitable
^
DISINFECnON AND DISINFECTANTS.
gas-heated machine. The former contained an exposed dish of water
during Dr. Parsons' experiments, whereas the latter did not; although
there is no apparent reason why such an addition should not be made
if found advantageous. In the Bradford apparatus, a range of
temperature of 24° F. was found to exist throughout the chamber, the
maximum being about 248° F. The moistening of the air was found
to have an appreciable effect in aiding the penetration of the heat, and
thus diminishing the period of exposure, and in Mr. Bradford's opinion
it also tended to preserve fabrics from injury at high temperatures.
filmiBmiiiHiiiS iiiiiiiiiiinjiiiiiiiiiiiiiiiliiiriiluLiiiiiiliii'irMrlliillilliliiiiiiiiiiiiiiiiniii.iiiiiiiiiiiiiuiiiiilliiliiiirliiiliiiiiHiiiii imc
Fig. 1. — Bradford's Hot- Air Disinfecting Apparatus.
On the other hand, it is clearly difficult to so stoke a firo as to produce
a uniform temperature in a large chamber (even opening the furnace
door caused a drop of temperature in the chamber of 7° F.), and the
success, or otherwise, of the process mu.st, therefore, largely depend
upon the skill and attention over several hours of the person in charge.
"No experiments appear to have been made with microbes in either
machine, so no definite proof is given that moist air at about 230° F.
has absolute germicidal properties, if continued for two hours only.
The construction of one form of this plant is given in Fig. 1. In Dr.
DISINFECTION BY HEAT. 27
Ransom's apparatus, which is heated by gas, the temperature may be
automatically governed by means of the now well-known mercurial
regulator, and on trial a variation of 9° F. was recorded in the
chamber, the minimum being 247° F. Although the time taken to get
up the requisite temperature and disinfect is considerable, the
apparatus can be left with safety to work without attention owing to
the gas regulator, and, in consequence, the drawback is much
minimised. In this case also, a constant stream of heated air passes
through the machine, which, no doubt, tends to preserve uniformity of
temperature, and perhaps accounts to some extent for the better
results than can be obtained in a coal-fired apparatus.
The chief drawbacks to hot-air disinfection are, therefore, due to
the slowness, and the danger of damaging the goods. It has also been
found that the process offers facilities, or even encouragement, to the
man in charge to scamp his work, for one can rarely tell by the
appearance that articles have been disinfected or not, and so great is
the risk of articles firing or being singed, if subject to a temperature
of 250° F. for several hours, and thus bringing the attendant into
trouble, that, as often as not, he takes the precaution never to allow
it to exceed 200° F. In one instance, at a dry -heat disinfecting
station in a densely populated London district, the attendant actually
prevented the air rising above 190° F. because expenses have been
incurred in the past for the replacing of damaged clcthing. This
farce has been going on for many years, and had not been altered in
1894. Such a state of things would be almost impossible if steam were
used, and, moreover, there exists no such temptation, for there is no
danger of damaging the clothing by heat in a well-constructed steam
apparatus, and the required temperature is obtained independently of
the attendant after his steam valve has once been opened. The
superior germicidal and penetrative qualities of steam have already
been referred to, and the only drawback to its adoption is that, unless
proper precautions are taken, the steam may condense on the articles
in sufficient quantities to damage them, and to necessitate drying
subsequent to their removal from the machine.*
Modes of Dealing with Condensation. — This question of condensation
roughly divides the several types of steam disinfecting apparatus into two
classes, viz., firstly, those in which provision is made to prevent copious
condensation by keeping the walls of the chamber at a higher tempera-
ture than the steam inside ; and, secondly, those in which no such
provision is made, and which frequently necessitate, as a consequence,
the subsequent drying of goods. Each of these classes might be
* See v. Esraarch, Zeksch.f. Hyg., Bd. iv. ; Graber, Oesundheits ingenieur, 18S8;
Badde, Archiv.f. Hyg., lid. ix.
"28 DISINFECTION AND DISINFECTANTS.
further subdivided into several others determined by the pressure of
the steam admitted to the chamber, by the currency or otherwise of
the steam in contact with goods, and by the introduction or addition
of apparatus necessary to create a vacuum in the chamber. Special
apparatus has also from time to time been made to overcome special
diflBculties, such as arise Avhen heavy bales of rags or merchandise
have to be treated in large quantities. The usual practice at home is
to erect a machine in which condensation is prevented l)y means of a
steam jacket or outer casing surrounding the chamber containing the
articles to be treated, and into which steam is admitted at a higher
temperature than that passing subsequently into the chamber. The
walls of the chamber being retained thereby at a higher temperature
than the steam admitted, condensation of the latter, due to contact
with cold walls, is absolutely prevented; but it must be borne in mind
that however valuable Washington Lyon's invention may be, it does
not absolutely prevent condensation on the goods themselves, which
are cold when first admitted, and only slightly warmed on the surface
by radiation from the hot sides and air convection due to the same
cause. There is, therefore, an initial condensation on the surface of most
goods when first brought into contact with steam, and consequently
a rise in temperature owing to the reception of the latent heat of the
steam during liquefaction. The fresh steam which next comes into
contact with the goods does not condense so largely, because they are
at a higher temperature than before ; but, nevertheless, liquefaction
does occur, and the articles again rise in temperature. This cycle of
operations repeats itself again and again rapidly, but finally the whole
of the articles are at the same temperature as the surrounding steam
and no further condensation occurs. The influence of the jacket then
becomes of greater importance, for it heats the steam, and no steam is
being condensed. The consequence is that the steam becomes super-
heated (the safety and reducing valves keep the pressure constant) and
is always kept in circulation by the convective effect of the sides ; the
result is that whatever moisture the goods may hold is re-evaporated,
so that they may be taken out substantially dry. It would appear,
perhaps, from the foregoing description that many delicate fabrics
would be damaged by even the temporary condensation at the com-
mencement of the process; but it is found iu practice that sur])risiDgly
little injury is done ; even the colours in cheap cotton print show no
signs of running, while delicately-tinted silk dresses are but little
affected by the condensation. Some materials lose their gloss, and
certain other woollen goods, such as new blankets, take the slightly
yellow tinge that would generally follow a good washing ; the only
goods which are absolutely damaged are those made of leather, or fur.
DISINFECTION BY HEAT. 29
These latter should always be treated by dry heat, or other means,
and the same remark generally applies to varnished or glued wood-
work, although heat of either sort when applied to finished woodwork
almost invariably leaves a record of its application of a more or less
serious nature.
Time and Steam Conditions required for Disinfection. — The precise time
required for disinfection in such a machine as has just been described
depends on three main factors — viz., firstly, on the particular disease
germ that it is required to kill ; secondly, on the nature and bulk of
the articles supposed to contain the germs ; and lastly, on the steam
pressure employed to secure penetration into the goods. It is, of
course, impossible to say whether any article contains only one species
of microbe, and also it is very frequently found to be practically
advantageous to treat at one operation the clothing, &c., of patients
suffering from several distinct maladies. As it also sinijilifies the
routine work of the attendant to have only one basis on which he may
calculate the total time required for disinfection, the minimum time
generally adopted should be that required for the steam to kill the
most persistent microbe when unprotected by foreign and artificial
surroundings. According to Dr. Klein and others anthrax spores have
hitherto been found to be among the more persistent forms of organism
affecting human beings, and, judging from their experiments, it may
be said that a free exposure to saturated steam, at 212° F. for fifteen
minutes, was a period in which sterilisation could be effected with
certainty. It was found that five minutes exposure under the same
conditions gave doubtful results, and, therefore, it is probable that
absolutely safe disinfection cannot be effected with steam under less
than ten minutes free exposure. This period was also found just
suflicient to kill lice and their eggs, for which purpose these machines
are sometimes almost entirely used in such places as workhouses. The
germicidal effect of saturated steam at a higher pressure of, say, 15 or
20 lbs. per square inch is usually supposed to be greater than that of
steam at atmospheric pressure ; in fact. Dr. Klein considered that its
efficacy might be taken for granted, and, therefore, made no experi-
ments of a similar nature by its aid. There is, however, one point to
which attention should be drawn ; steam may be either " saturated "
or " superheated," but the germicidal influence of the two is considered
by many to be different, although the steam is dry in both conditions,
and either form may exist at any pressure or in the absence of water.
These two facts are mentioned, because in the minds of some saturated
steam is commonly associated with moisture, and sujjerheated steam is
confused with steam under pressure. The two forms are distinguished
entirely by their temperature — that is to say, steam may just exist at
so DISINFECTION AXD DISINFECTANTS.
227*95° F. under an absolute pressure of 20 lbs. per square inch (i.e.,
including atmospheric pressure), or by adding more heat to it, its
temperature will rise, say, to 300° F. at the same pressure although
its volume will increase, and in this condition it is said to be super-
heated. In most, if not all, steara-jacketted machines the earlier
portions of the operation must perforce be conducted with saturated
steam, and in the better machines, from which the articles come out
absolutely dry, it is probable that the steam contained in the chamber
becomes slightly superheated towards the end of the process. Hence,
it matters but little in a jacketted machine whether saturated or
superheated steam be the better disinfecting agent, for steam may be
used in both conditions. As a matter of fact, the difficulty has always
been to bring the articles out dry, and so long as they come out with
even ^ per cent, added moisture, it is certain that the steam has never
been entirely superheated.
The question of steam pressure to be employed is one which has
been much debated, and at the present time there are machines (mainly
on the Continent) which employ steam at 1^ lbs. pressure ; and others
again working with steam at 20 lbs. pressure. Assuming, for the sake
of argument, that the higher pressure steam has no greater germicidal
effect than the lower (which is not probable), it still has many im-
portant practical advantages which are of great value in most cases.
When bulky articles, such as mattresses, rolls of carpets, &c., have to
be treated, or when the machine must be filled so entirely that the
air space between each article almost disappears, then it is clear that
penetration of 20 lbs. steam will take place far more rapidly than if
this pressure be only 1 or 2 lbs. Or, again, a machine which uses
steam at 20 lbs. pressure may be worked off almost any existing boiler,
because almost all steam generators nowadays work at pressures above
that required, and, although it is a comparatively simple matter to
reduce the pressure automatically to 20 lbs., it is not nearly such an
easy problem to reduce the pressure sufficiently so that the steam may
be used with safety in apparatus designed to stand 1| lbs. only. This
difficulty may entail the erection of a special lx)iler of unusual design,
and steam is then raised under conditions the reverse of economical.
It is also noteworthy that condensation is more likely to take place
when low-pressure steam is used than when steam at a higher tempera-
ture is admitted. The main objection to high-pressure apparatus is
that the machines require not only greater strength, but also more
careful design, and are consequently more costly. There are occasions,
doubtless, when, on economical grounds only, the low-pressure machine
is allowable; but the circumstances, even in these cases, should be
such that time for drying articles can always be allowed subsequent
DISINFECTION BY' HEAT. 31
to treatment. Although steam can, as has already been shown, pene-
trate the bulkiest article in a comparatively short time, this period
may, by a little manipulation on the part of the attendant, be very
materially reduced. In arranging the goods in the chamber, every
care should be taken to leave a little space l:)etween each of the various
i-olls or bundles. Often a few ])ieces of wood or a rough hurdle may
come in very useful when articles have to be piled one on the other,
or things can be hung up readily so as to allow of circulation. In all
cases it is safest not to permit the attendant to handle infected articles
more than is absolutely necessary ; therefore, bundles or rolls ought
not to be themselves unpacked, although such a proceeding would
undoubtedly hasten the process. Again, after the chamber has been
closed (assuming it to contain bulky articles), penetration may be
greatly facilitated by relaxing the pressure and refilling several times
during the process. Thus, if the chamber be filled with steam at
20 lbs. pressure in two minutes, this steam may l)e allowed to remain
stagnant for say tAvo minutes, and then allowed to escape. It should
immediately be refilled with steam, and perhaps five minutes later
again allowed to escape, and so on. It is probable that this procedure
is advantageous owing to the large amount of air retained in woollen
and other goods, which is compressed by the steam into their centre,
and if not allowed to distribute itself throughout the chamber by
removal of piessure, would greatly retard penetration. It has been
found that rolls of blankets, rolls of carpets, and compressed bales
are among the most difficult articles to disinfect, and in such cases
the precautions just referred to should most certainly be adopted.
Mattresses and pillows can readily be separated one from another, but
if this be not done, considerable time may be required for these also.
There is still one difficulty which arises when heavy charges are placed
in the machine, and that is due to the internal condensation in the
centre of the goods. The explanation of the causes promoting con-
densation will have made it clear that such difficulties will be more
difficult to eradicate in large bundles than in small ones ; and, as a
matter of fact, it is generally the rule that moisture will be perceptible
in the centre of a large roll in spite of the steam jacket. It is clear
that condensation may be entirely avoided in the first place if the
goods be raised to the temperature of the incoming steam prior to its
admission ; but it has been shown that in dry-heat stoves it is a very
lengthy operation if the goods be bulky. The length of time is due
very largely to the fact that the hot air is not forced into the centre of
the goods ; in fact, it has little more than a surface action, and, as a
consequence, the goods usually act as a capital non-conductor to protect
the interior, and the cold air retained there. But if we assume that
32 DISINFECTION AND DISINFECTANTS.
this contained cold air could be withdrawn, and the hot air subse-
<|uently forced in to take its place, we get a very different state of
things, and the heating can obviously be effected far more rapidly.
This course is practicable if steam be available, for the removal of
air and the compulsory substitution of other heated air al)sorbs more
work than could be expected from an attendant if steam power were
not at hand, as is the case when dry-heat disinfectors are employed.
The whole process may be completed by merely creating a vacuum
in the chamber and then admitting heated air at atmospheric pressure.
It is a very simple matter to withdraw the bulk of the air by a simple
steam jet arranged after the fashion of the ordinary spray producer
until a vacuum of 20 inches is indicated on the gauge ; and then, if
the chamber be placed in communication with the atmosphere, air is
forced in at a pressure of about 10 lbs. to the square inch, and, in
transit, it may be passed through a short coil of pipe surrounded by
steam at the required temperature so as to heat it to the most suitable
degree. There are many features about this process to recommend it ;
for, not only is it possible to regulate the temperature of the incoming
air to a nicety, but it is also itself easy to heat, because it is constantly
in motion, and, for the same reason, the hot air itself heats the goods
it comes in contact with the more rapidly. If the air be passed through
pipes heated by the direct heat of a fire, it becomes almost impossible
to control its temperature, and the same dangers of scorching arise as
■were found by the use of dry heat stoves. In the class of apparatus
described it has been found desirable to keep the temperature of the
incoming air to about 220° F., so that, when steam is admitted at
250° F., it does not become superheated, and its germicidal influence
is not affected. Supposing, for the sake of argument, that moisture
still remains in goods after steaming, the presence of the vacuum and
hot-air apparatus is still of great value ; for by its aid the articles may
be dried to any extent desirable at a far lower temperature than
"212° F. The vacuum has several other advantages quite apart from
its drying qualities. It enables the operator to remove most of the
air from the chamber before the admission of steam ; consequently,
the ordinary steam pressure gauge may be read accurately as a
temperature gauge, seeing that the mixture of steam and air has not
to be considered, whereas the temperature of saturated steam varies
with its pressure.
Also, the production of a good vacuum * prior to the admission of
* The term vacuuyn is not intended to implj' the total absence of gases ; a space
filled with a gas, and under a pressure equal to that of 20 inches mercury as
measured by the vacuum gauge, would be generally referred to as a fairly good
VACuum.
DISINFECTION BY HEAT. 3S
steam is equivalent to raising its pressure, so far as its penetrative
power is concerned ; consequently, the rapidity with which bulky
articles are disinfected is very much increased, although the tem-
perature at which they are treated remains unaltered. It thus
becomes possible to disinfect goods with steam at only 10 lbs. pressure
as rapidly as with steam at 20 lbs. pressure, when no vacuum is created.
Both these points are of importance, since of late years the practice has
become prevalent to treat very bulky things, such as rolls of carpets,
compressed bales, <fec., and as the amount of work to be done is thus^
much increased the disinfecting chamber is commonly packed closely.
Moreover, the damage done to delicate fabrics, which sometimes lose
their gloss at 250° F., may be entirely avoided by disinfecting at say
220° F., without any increase in the time required to secure penetra-
tion. Altogether, the advantages to be gained by the introduction of
this inexpensive and simple vacuum apparatus are considerable, and
great credit is due to the inventors (Mr. J. B. Alliott and Mr. J. M.
C. Baton).
Experiments on the Penetrating Power of Steam. — An idea of its
powers may be gathered from a comparison of the following two trials.
In p. 296 of Dr. Parson's report it is stated that a cotton rag press-
packed bale was tested in a Washington-Lyon machine. The dimen-
sions of the bale were 3 feet fi inches x 3 feet x 2 feet 3 inches, and
its weight was 5 cwts. At the end of four hours a thermometer at
its centre registered 258° F., and the increase in weight was 4"8 per
cent. Experiments were made in 1893 with a similar machine, but
fitted with the vacuum apparatus, on a press-packed bale of cotton rags
weighing 5 cwts. 3 qrs. 13 lbs., and measuring 3 feet x 2 feet 4 inches
X 4 feet 6 inches. The trial was conducted on similar lines, and every
precaution was taken to prevent the passage of steam down the hole
through which the thermometer had been admitted by plugging it
up with a long conical piece of wood larger in diameter than the
hole itself. The thermometer was so arranged that when the mer-
cury column reached a height equivalent to 220° F., an electric bell
was rung outside the chamber. The bell rang precisely forty-five
minutes after the introduction of the bale to the chamber, and it was
removed after a final drying by the vacuum and hot air after a further
period of thirty-three minutes. The whole time taken was seventy-
eight minutes, and the total increase in weight was less than 2*6 per
cent. The bale was again submitted to the air-drying for fifteen
minutes, with the result that the moisture was further reduced by
30 per cent.
The accompanying chart shows the mode of working adopted during
this trial, although it would probably have hastened the process had
3
34
DISINFECTION AND DISINFECTANTS.
the alterations of pressure and vacuum been more frequent, and it was
also a mistake to have admitted the steam immediately on obtaining
the first vacuum, instead of admitting and extracting hot air prior to
the admission of the steam. The particular trials referred to are not
such as will have to be frequently repeated in public disinfecting
stations, but they have been given merely as indicative of the greater
penetrative and drying powers of jacketted disinfectors when fitted
with vacuum apparatus. If bedding or clothing has to be treated the
so
«20
/ \
+220''F reached /n-h.
C
S
/ \
centre of Bale..^ \
2
2 10
ft.
• 99
s.
/
/\
\
\
k.
.
/
\
1 \
\
§ o
■
/
Duration
of Trial in Minutes.
\
■
/.
\ / , J ,
, \.
/ '°
so
N^ 40
50 ^
•^^^60
70
/SO
10
'•S\ /
\/
^
/
Fig. 2. — Chart showing effect of vacuum of apparatus on the penetrative
power of steam.
duration of the process is considerably shorter in either form of
apparatus ; but there still remains the same advantages in favour of
the machine fitted with the vacuum apparatus.
English Apparatus — Washington-Lyon's Patent. — In this country
the machines mostly in use are those made under Washington-Lyon's
patent. This is largely owing to the far reaching nature of Mr. Lyon's
specification, on which much litigation has taken place. Generally
speaking, these machines are made in two forms, square and oval in
section.
The square form (until recently known as Goddard's patent, made
by Goddard, Massey, & Warner, of Nottingham) is jacketted all
round the body, in addition to the two doors. The jacket in this case
is usually half filled with water, and is used as a boiler. The fire-
grate is placed immediately under the body of the machine, and the
firebrick flue (see Figs. 3 and 4) is built to traverse the bottom, and
thence along other flues, built around the sides of the machine, to the
chimney. The steam pressure in the jacket (i.e., the boiler) is usually
limited to 20 lbs., and disinfection is carried on by steam at the same
and lower pressures. Arrangements are also provided for passing a
current of hot air through the chamber before and after disinfection.
The air is heated by passing it through a pipe situated in the furnace
DISINFECTION BY HEAT.
35
flue immediately under the disinfector, and thence into the chamber.
The air may be circulated and extracted from the chamber by means
of a small exhauster. This apparatus has had a considerable sale
owing largely to its rectangular form, and there can be little doubt
that it disinfects adequately, and also that when properly worked there
should be little or no moisture present in the goods subsequent to
disinfection. Its apparent first cost is also a factor in its favour,
although if the cost of the necessary brickwork setting and side flues
be added to the cost of machine and erection, this advantage is more
Fig. 3. — Sectional plan of Goddard & Co.'s square form of Washington- Lyon's
disinfecting chamber.
apparent than real. Its chief disadvantages are, curiously enough,
precisely due to those features which are presumably advantageous.
For instance, the square shape is to some an attraction, whereas it is
undoubtedly a constructive weakness, and for obvious reasons the
most suitable section for a steam chamber to stand a considerable
internal pressure would be circular. Thus this advantage has to be
paid for in the shape of repairs to leaky joints, insurance, &c., although
possibly, in certain cases, it may be worth the risk. Again, the use of
the jacket as the boiler is advantageous inasmuch as less space is
required ; but, on the other hand, it is an imperfect boiler, which
cannot be got at properly for cleansing, and is likely to be the cause of
36
DISINFECTION AND DISINFECTANTS.
mishaps, especially at the bottom (which is not readily accessible for
examination), where the fire impinges directly on the flat plate, and
gradually burns it away. The presence of jacketted doors is also a
feature of this machine, although it is doubtful if this additional com-
plication is necessary when the hot-air apparatus is also supplied. The
air is heated by the action of the hot gases of the fire, and the only
THERMOMETER
HOT AIR
COCK
COLD AIR TO
REGULATE
TEMPERATURE
Fig 4. — Section through Goddard. & Co.'s square form of Washington-Lyon's
disinfecting chamber.
precaution that has to be taken in reference to this point is to warn
the attendant not to raise too large a fire when using the hot-air
blast ; for, if this point be not considered, the air may attain a scorch-
ing temperature, and so damage the contents of the chamber.
The size of this disinfecting chamber is usually 5 feet x 5 feet x
6 feet 6 inches internally, although machines of smaller dimensions
are also made. The following experiment, made on a new machine
in 1893, gives an idea of the working of this apparatus : —
The fire was lighted at 10.8 a.m., the water in the jacket being cold, although
the brickwork was still warm from the previous day's work. At 11.45 a.m. the
DISINFECTION BY HEAT. 37
pressure gauge showed 10 lbs. steam pressure, and at 12.0 noon it indicated 194 l^^*
pressure. The total time occupied for raising steam took one hour fifty-two
minutes, and about 1 cwt. 1 qr. of coal had been consumed. The door was then
opened for the admission of clothing. Three minutes were occupied in opening
and four minutes in closing the door. At 12.10 p.m. the exhauster was set to
work, and hot air was drawn through the chamber until 12.20 p.m., ten minutes
in all. The chamber pressure gauge reached 5 lbs. at 12.204 p.m. ; 10 lbs. at
12.214; 15 lbs. at 12.23; 19 lbs. at 12.27; and 20 lbs. at 12.31. During this
period, from 12.20 to 12.31 p.m., the jacket pressure fluctuated between 19 and
20 lbs. At 12.23 p.m. the steam escaped freely from one of the doors which had
presumably slightly sprung. This happened again subsequently, and had to be
remedied by tightening the bolts securing the doors. At 12.31 p.m. the addition
of feed-water to the boiler caused the pressure in the chamber to fall to 17.^ lbs.
Steam to the chamber was shut ofiF at 12.35 p.m., and the chamber was then
exhausted. From 12.35i p.m. to 12.44J p.m. hot air was again drawn through the
chamber, and the door was opened at 12.48 p.m. A certain amount of vapour
escaped through the door on opening, and some water was found at the bottom of
the chamber. The goods which were hung up, consisting of overalls, were fairly
dry and not damaged. A maximum thermometer which had been exposed in
. the chamber registered 260° F. The total process of steam raising and first
disinfection occupied two hours and forty minutes, and the total fuel used
amounted to about 1 cwt. 2 qrs. The time for disinfection only after steam has
been raised was forty-eight minutes.
Dr. Whitelegge has been good enough to give the following figures
relating to some trials made with this apparatus at Leicester in 1889.
The process was similar to the foregoing, but the total time occupied
was only twenty-seven minutes, which, apparently, was too little to
secure penetration. The following are his results.: —
When removed after disinfection, a horsehair pillow, weighing originally 2 lbs.
84 0Z8., was increased 1^ ozs. in weight ; it was damp inside but dry on cooling.
The thermometer in centre indicated 241° F. A flock pillow was increased only
4 oz., the initial weight being 3 lbs. 84 ozs. This was also damp inside, but dry
on cooling. The thermometer at centre showed 234° F.
Three blankets, each folded into 16, piled one above the other on the floor,
were wet at centre and bottom even on cooling, and the thermometer at centre
indicated 166° F. Dr. Whitelegge also took the temperature of the chamber at
different parts when the hot air only was admitted.
Temperature in hot-air inlet, touching the pipe, was . . . 289° F.
,, on pillow 1 ft. from inlet, ,, . . . 252° F.
„ on floor near inlet, ,, . . . 247° F.
The temperature in chamber due to radiation and convection only, with sknd
without air current, was as follows : —
The middle of floor after 15 mins. =239°
,, roof „ =245°
The roof near door ,, =239°
The floor „ „ =241°
The other form of disinfector generally used in this country is that
originally known as Washington-Lyon's, and is made by Manlove,
F.,
or after 5 mins. with ejector only 237° F.
F.,
250° F.
F.,
246° F.
F.,
241° F.
38
DISINFECTION AND DISINFECTANTS.
Alliott <fe Co., Ltd., Nottingham. The leading points of diflference
between this and that made by Goddard & Massey are (1) that the
boiler, except in the locomotive type, is usually kept distinct and
separate from the disinfector, and (2) that the section is usually oval
or round. As made during the past two years, the vacuum apparatus
invented by Messrs. Alliott & Paton has generally been added, which
is in itself a distinctive feature, although only of recent introduction.
In Fig. 5 we show one of this firm's disinfectors of the old type, and
in Fig. 6 the same fitted with Alliott & Paton's patent vacuum
apparatus. Fig. 7 shows a portable steam disinfector for purifying
wearing apparel and bedding in rural sanitary districts. This machine
has a circular chamber 5 feet long and 2^ feet diameter. The larger
Fig. 5. — Manlove & Co.'s form of Lyon's disinfector (old type).
form shown in Fig. 8 has a chamber 7 feet x 4 feet 2 inches x 2 feet
7 inches, and is fitted with the vacuum apparatus.
With this class of apparatus, a special boiler is, of course, not
necessary when steam can otherwise be obtained. The pressure
in the steam jacket is maintained at 32 lbs. per square inch, but
the boiler pressure may be anything above this, as steam entering
the jacket is automatically reduced to the required pressure. In the
chamber, the steam pressure is maintained (also automatically) at
22 lbs. In apparatus not fitted with the vacuum arrangement, the
pressures in jacket and chamber are usually 25 lbs. and 20 lbs.
respectively. The higher pressure in the first case is found more
convenient for the double purpose of air heating and extraction.
This machine when fitted with the vacuum apparatus, may also be
used as an efficient dry heat disinfector, since hot air is admitted into
a partial vacuum, which, in other words, is equivalent to working with
hot air under pressure. The air is heated by passing it through pipes
DISINFECTION BY HEAT,
39
surrounded by steam at a constant temperature, and the danger ot
scorching is thereby obviated. The larger sizes of the machine are
Fig. 6. — Manlove & Co.'s form of Lyon's disinfector fitted with
a TacuQm apparatus.
— -'■T^firH' H'tAiii'Ts. Ji'
Fig. 7. — Portable steam disinfector (Manlove A Co.).
usually oval in section, and the smaller sizes round. This is presumably
with the object of obtaining greater strength and durability, and in
40
DISINFECTION AND DISINFECTANTS.
the oval form the largest articles can be disinfected without great
expenditure of ground space. The separate boiler admits of ample
inspection in the ordinary ways, and; if erected at the same time as the
disinfector, contains, in the most recent designs, arrangements for
burning the whole of the gases exhausted from the disinfection chamber
before passing them into the atmosphere. The best mode of working
this apparatus under ordinary conditions is to admit a current of hot
air for a few minutes, then obtain a vacuum, and break it with steam
at 20 lbs. pressure. The steam having done its work of disinfection is
discharged, a vacuum is again obtained, and a current of hot air
Fig. 8. — Larger form of portable steam disinfector with vacuum apparatus
(Manlove & Co.).
completes the process. In the experiments on a medium size machine,
details of which are given below, this course was not closely followed,
as it is the best only when the machine is very full, or the articles
are bulky.
Experiments on a Washington-Lyon's Patent Steam Disinfector when
FITTED with AlLIOTT & PaTON'S PaTENT VaCUUM APPARATUS.
No. 1. — Charge, 4 mattresses and 4 pillows.
109 lbs. 1 oz.
Weight before disinfection =
11.30 a.m.
doors close
a.
11.32 „
vacuum
16"
broken by hot air.
11.34i „
11.364 M
)>
16"
>> *>
11.39 „
11.41 „
»»
16*
„ steam.
11.43 „
11.47 „
steam
16"
maintained till 11.50 a.m
11.62 „
11.55 „
vacuum
11"
broken bj hot air.
11.57 „
DISINFECTION BY HEAT. 41
11.58 a.m.
vacuum
10"
broken by hot adr.
12.0 noon
12.24 pm-
*>
16"
II II
12.4i „
12.6} „
>>
16"
circulation by hot air begun.
12.9 „
»>
10"
i» II
12.12 „
doors opened.
Total time =
42 minutes.
Total
increase in weight =
1 oz., or 0-05 per cent.
No. 2. — Two blankets fresh from the laundry wringing machine were next put
in the disinfector. One blanket contained a large amount of soap, and it was
noticeable that this one took far longer to dry than the one which was com-
paratively free from soap.
Before disinfection, the total weight was 15 J lbs. After 50 minutes one blanket
was nearly dry, and weighed 3 lbs. 3 ozs. The soapy blanket weighed 4 lbs. 2 ozs.,
and was perceptibly moist.
The two, therefore, weighed 7 lbs. 5 ozs., or a reduction in weight of 54
per cent.
These blankets were then put back into the machine and completely dried, their
total weight in that condition being about 6| lbs.
No. 3.— Subsequently, a charge of bedding was treated, consisting of blankets,
pillows, sheets, &c.
The total weight before treatment was 29| lbs.
,, after ,, 28 ,,
Total time = 35 minutes.
Diminution in weight = 1 lb. 6 ozs. , or 4^ per cent.
In none of the foregoing experiments were the articles in any way damaged.
Dr. Whitelegge also made some experiments on this form of machine
in 1889, when it was not fitted with the vacuum apparatus. Permis-
sion has kindly been given to refer to them here, but space does not
allow of their being dealt with as fully as they deserve : —
Steam was admitted to the jacket at 10 lbs., but the steam entered the chamber
at a pressure of 5 lbs. only. A thermometer was placed inside one of the bulky
articles to be treated, and so connected as to ring an electric bell oatside when
a temperature of about 220° F. was reached.
The door was closed at 12.35.
Steam was turned on at 12.37.
5 lbs. pressure in chamber at 12.38.
Bell rang 12.53^ (the bell ceased in 20 seconds upon intermitting the pressure
inmiediately after this).
Steam was shut ofif at 12.56.
Door slightly opened to facilitate drying at 1.0.
Door opened wide, dry air inside, 1.5.
(a) Horse-hair pillow (2 lbs. 7i ozs.) weighed 2 lbs. 9i ozs., and was damp in
centre, but dry on cooling. The electric thermometer at centre rang in 16
minutes, and corrected reading gave 223° F.
(6) A flock pillow (3 lbs. 6| ozs.) weighed 3 lbs. 9 ozs. (?), and was damp in
centre, but dry on cooling. The corrected temperature was 219° F.
42 DISINFECTION AND DISINFECTANTS.
(c) Blue Saxony flannel nf ^ 15 afterwards measured ^m ^ 141 and was
slightly yellow, but not felted.
21^ ' 15" 20i 154
(rf) White, unshriukable flannel -st^ ^ ,-7^ measured afterwards sTi ^Txl*
This also was slightly yellow, but was not felted.
(e) Six sami)les of coloured silk, pleated, were unchanged, except that the dark
green became wet and black. These had been placed near the door.
(/) Thick book (Churchill's Directory) on floor was cool inside. Thermometer
placed uncovered in other parts of machine showed temperatures varying from
228° F. to 234° F.
A further experiment was then made on following lines : —
Door was shut at 1.21 p.m.
Steam admitted 1.22.
Full steam pressure attained in chamber (5 lbs.) 1.23.
Pressure was intermitted at 1.31.
Bell rang at 1.35.
(o) Two blankets, each folded into sixteen layers, laid one above the other on
the wooden floor, were damp on removal, and dry on cooling.
The electric thermometer at centre — i.e., with sixteen layers of cover — showed a
corrected temperature of 228° F. The bell rang in 12 minutes.
Another experiment was made with low-pressure steam, with ^ lb. pressure in
both chamber and jacket.
Door was closed at 2.17.
Steam at ^ lb. pressure in chamber at 2.20.
Bell rang at 2.37.
(a) Two blankets arranged as before were wet, but became immediately dry on
shaking. The bell rang in 17 minutes, and the thermometer showed a tempera-
ture of 214° F.
(6) Horse-hair pillow came out steaming, and thermometer indicated 216* F.
at centre.
(c) A flock pillow came out steaming, and the thermometer at centre indicated
213° F.
It is noteworthy in Dr. Whitelegge's experiments, that when steam
at 5 lbs. pressure was used the thermometer at centre of blankets
registered 228° F. in twelve minutes, and that when steam at J lb.
pressure was used the thermometer, under apparently identical
conditions, indicated only 214° F. after seventeen minutes, and also in
the latter case pillows were taken out steaming. Although the types
of disinfecting apparatus described are not absolutely the only ones used
in this country, probably more than three-fourths of those erected in
the past ten years have been of these types.
TYPES OF DISINFECTORS USED ON THE CONTINENT.
1. Austria — Thursfield's Apparatus. — On the Continent, several
foreign designs have been extensively used, ^and some of these are
DISINFECTION BY HEAT.
43
occasionally to be met with in this country. Fig. 9 represents a
portable form of apparatus used to some extent in Austria, and
Fig. 9. — Thursfield's portable disinfector (large).
designed by Mr. Thursfield, of Vienna. It is, in the modern patterns,
usually circular in section and jacketted ; the jacket is partially filled
with water, and acts as a boiler
with the fire underneath. The
boiler is open to the atmosphere,
and, therefore, when steam is ad-
mitted to the chamber it is only
at 212° F. A continuous current
of steam is kept passing through
the chamber, and as the latter is
jacketted by the boiler casing, con-
densation is largely minimised, and
the inventor states that clothing
removed after treatment is only
slightly damp. After each disin-
fection the boiler is partially refilled
with cold water, and, consequently,
ebullition ceases for a time. It is
stated that the boiler contains 20
gallons of water, and can generate
steam in twenty-five minutes from water at 50° F.; the total time
required for one disinfection is said to be sixty-eight minutes.
Fig. 10. — Thurslield's portable
disinfector (small).
44 DISINFECTION AND DISINFECTANTS.
Maximum thermometers placed inside diflferent articles registered
218° F. The consumption of fuel during the above trial was said
to have been only 7 lbs. wood arid 19 lbs. of coal. A smaller form
of the Thursfield disinfector is shown in Fig. 10.
2. France — The Equifex Stove. — A common type of apparatus in
France is that made by Geneste, Herscher & Co., of Paris. This
machine is externally not unlike those of Washington-Lyon, although
its construction is materially different, inasmuch as there exists no
steam jacket, and only comparatively low-pressure steam is employed.
It is made in several sizes and types, which may be briefly described
as follows : —
(1) It is a fixed machine working with steam at from 7 lbs. to
10 lbs. per square inch ; consequently the maximum temperature to
which the infected articles are exposed is from 230° F. to 240° F.
The large size is commonly 6 ft. diameter and 13 ft. 6 in. long,
inside of which are two sets of steam-pipe coils. Each set consists
of eleven pipes running the whole length of the machine, one being
placed at the top, the other at the bottom of the chamber. These
coils are so arranged for drying purposes, and to prevent condensa-
tion. Arrangements are made to enable the air to escape through
a pipe at the bottom of the disinfector pending the admission of steam,
with which the disinfecting process is commenced. When the pressure
has reached 7 lbs. to 10 lbs., the steam is exhausted and a fresh quan-
tity admitted. In this way the inventors claim that sufficient pene-
tration is secured without the aid of steam at a higher pressure, and
also that it is only necessary that steam at 10 lbs. be actually in
contact with the goods for not less than fifteen to seventeen minutes,
in addition to the time taken in filling and exhausting the chamber,
which should be done not less than three times during the operation.
Before the goods are taken out it is recommended that they be left
in the closed machine for some time to dry, although the precise time
taken by this process is not clear.
(2) Messrs. Geneste, Herscher & Co. also make a type to work at
from 2 lbs. to o lbs. pressure with current steam. In this machine
the temperature to which the goods are exposed does not exceed
217° F. to 222° F. The inventors make a point of bringing the
steam into the chamber at the top and extracting it at the bottom,
and say that the air in the chamber is thereby effectively driven
from the chamber. The steam pressure in the case of this machine
is too low to make the relaxation and renewal of pressure of
any benefit to penetration. The steam is only nominally "current"
because the outlet is governed by a modified form of reducing valve.
A feature of the apparatus is that the two doors are so interlocked
DISINFECTION BY HEAT.
45
46 DISINFECTION AND DISINFECTANTS.
that it is impossible to have the two doors open at the same time, but
otherwise the arrangements of this type are similar to those in the
other. In Fig. 11 we give an illustration of an Equifex horizontal
stove working with confined steam.
The disinfecting chamber, A, is a wrought-iron cylinder without jacket or other
means of superheating the steam, but lagged with wood and coated with a non-
conducting composition. The stove usually passes through a partition, B, to
separate the infected objects from the disinfected. The doors, C, D, are fitted with
an arrangement making it impossible for both to open at the same time, and are
secured by nuts, E, locking into solid steel recesses, F, on the door. A row
of steam tubes runs longitudinally inside the stove for warming the stove
before and during disinfections, and for heating the air which is used in the
subsequent drying of thick objects. The steam is led to the stove by a pipe, G,
from the boiler, and, after traversing a separator, H, passes through the reducing
valves, T, K, and safetj' valves, L, M, to the stove and tubes respectively. When the
desired pressure is reached in the tubes, as shown by the gauge, N, steam begins
to escape through the safety valve, M, and the attendant then regulates the pres-
sure by the reducing valve, K. The stove, having thus been warmed, is charged
with the objects, 0, to be disinfected, which are loaded in the ordinary way on to
a wheeled carriage, P, running on rails within the stove, and on hinged rails, Q,
outside. The door is then closed, and locked with the safety nuts, E, and the
valve, I, is opened, allowing steam to pass through the safety valve, L, into the
body of the stove. The steam enters the stove through an internal sparge-pipe
fitted longitudinally inside it towards the top, and furnished throughout its length
with a screen to assist in the thorough projection of the steam to all parts of the
stove. The steam is at first allowed to escape through the air discharge pipe, R,
and carries with it the air from the stove. The discharge pipe, R, is fitted with
a thermometer, S. When the air is ejected, the mercury will rapidly rise to 195°
to 205° F., at which point the valve, T, controlling the pipe, R, is closed. The
steam continues to enter the stove through the valve, I, till it reaches a pressure
of 10 lbs. per square inch, as marked on the gauge, U, when it escapes through
the safety valve, L, until the attendant has regulated the pressure by the
reducing valve, I. A film of water is formed throughout the pores of the
object under a pressure just sufficient to keep it from evaporating. Advantage
is taken of this fact to get rid of the air secreted originally in the pores of
the object by shutting off' steam occasionally (say every five minutes) by
means of the valve, I, and opening the sluice valve, V. The sudden reduction of
pressure so eff'ected causes a sudden re-evaporation of the condensed steam in the
objects ; so what was water in the pores expands into steam of some sixteen
hundred times its volume, sweeping out before it the air from the pores. To
assist this process the stove is fitted with a pneumatic exhaust, operated without
any moving parts by the steam pressure. For this purpose a jet of steam is
allowed, by means of the valve, W, to pass up an aspirator or ejector fitted in the
steam discharge pipe, X, so automatically sucking out both the steam and the air
ejected from the jwres, and producing a partial vacuum under which the vaporisa-
tion of the steam and the ejection of the air is completed. With objects of
ordinary thickness disinfection is complete in fifteen to seventeen minutes.
Steam is then let off" as before ; and on the door being opened, all objects such
as blankets, clothes, &c., are taken out and shaken, when they will be found to
be perfectly dry. Mattresses and thicker objects are replaced in the stove for
five minutes for the aspirator to withdraw the steam.
DISINFECTION BY HEAT.
47
3. Denmark — Reek's Apparatus. — In Denmark, Mr. A. B. Reck, of
Copenhagen, has designed an apparatus which contains some features of
novelty j but, like most of the foreign apparatus, it does not aim at so
much as those of English design, and he is content to disinfect " in such
a manner that things would be spoiled by steam as little as possible."
The inventor attributes the presence of moisture in goods almost
entirely to the inrush of cold in the presence of vapour, and his
improvements are directed towards diminishing this evil. After the
goods have been steamed (at about 1^ lbs. pressure), a spray of water
is injected at the top of the chamber in such a way as not to impinge
on the clothes, and, simultaneously, a large air valve is opened at the
f° i« i»
1 ^ 1*
i— 1« P 1^ ^,„h
Fig. 12. — Reek's steam disinfector (transverse section).
bottom. It is claimed that the steam contained in the chamber rises
to the top, is condensed by the cold water spray, and the momentary
partial vacuum so produced is re-occupied by air rushing in at the
bottom of the chamber. In this way the whole of the vapour is con-
densed and carried away with the water, and when the chamber door
is opened cold air only is present. The main difficulty of condensation
on the clothes during disinfection due to radiation, and their own low
48
DISINFECTION AND DISINFECTANTS.
temperature, is not dealt with in any way, either by steam jacketting
or preliminary heating by hot air.
In Figs. 12 and 13 we show two sectional views of Reek's apparatus.
Dr. Reid has lately tested this form of disinfector, and has reported
favourably upon it to the Stafford County Council.
4. Germany — Schimmers and Budenberg's Apparatus. — A disinfecting
apparatus largely used in Germany is that made by Oscar Schimmel,
.3Mcter
Fig. 13. — Reek's steam disinfector (longitudinal section).
of Chemnitz. There is nothing very striking in its design, and pro-
bably the explanation of its extensive use may be found in the fact
that it was one of the first to be placed on the market. The claims
made are, broadly speaking, three. First the clothes are warmed by
hot air to a temperature of 60° C; secondly, they are steamed by
current steam at atmospheric pressure ; and lastly, they are partially
dried, and aired again by warm air. No pretence is made that the
articles come out perfectly dry, or that the process is a rapid one, but
it is justifiably claimed that articles which are not too bulky are
disinfected, and also that the first cost of the apparatus is moderate.
DISINFECTION BT HEAT.
41>
Fig. 14 shows a small vertical type with steam-generating apparatus
and fire beneath. Steam rises round the chamber in which the clothes
are situated, and enters at the top and leaves at the bottom, while
condensed steam returns to the boiling apparatus. Great care would
have to be exercised to see that water never ran short in the domed
bottom, for it is very small in quantity, and would need frequent
Fig. 14. — Schimmel's vertical steam dlsinfector.
replenishing by hand through the funnel. When a charge has been
disinfected, the fire has to be drawn in order that steam may be pre-
vented from passing into the chamber. To obtain air circulation, a
small door is removed in the crown, and, the exhaust pipe being also
open, a certain air circulation is obtained owing to the heat retained in
the clothing and walls of the chamber.
In the larger size shown in Fig. 15, which is oval in section, more
elaborate arrangements are provided for air heating, «kc., and steam
has to be obtained from a separate boiler. The gilled pipes at the
bottom are filled with steam at boiler pressure, and thus to some
extent they check condensation in the chamber when steam at atmo-
spheric pressure is admitted. Air circulation is again obtained entirely
by the crude method of opening a small door at the bottom of the
4
DISINFECTION BY HEAT.
M
chamber close to the gill pipes, and allowing it to rise and escape at
the top by the exhaust pipe. Machines of this type have been at
work in Berlin for about ten years. In the larger apparatus it is
usual to admit current steam to the chamber at about 1^ lbs. pressure.
It is necessary when working the apparatus, first to warm it up by
hot air for not less than thirty minutes, and then, after putting in the
goods, to again warm them for thirty minutes or thereabouts. Steam-
ing is said to take about thirty minutes (although this must surely
depend largely on the articles being treated), and the final drying
occupies another fifteen minutes. The whole process, including load-
ing and unloading the truck, should, therefore, mean an expenditure
of time amounting to nearly two hours ; and, even when taken out,
the articles are supposed to undergo a further process in an ordinary
drying closet.
Fig. 16. — Budeuberg's steam disinfectiug apparatus.
The general arrangements of Schimmel and Geneste Herscher's
apparatus all bear a considerable resemblance the one to the other,
and it is difficult to see how the actual work done by the various
designs should be very different in result. It is, therefore, to the
credit of Herr Oscar Schimmel that he should almost alone admit the
weaknesses of his apparatus, and at the same time give financial
reasons as a valid excuse. The apparatus of W. Budenberg, of
Dortmund, works at about 3 lbs. pressure, and is very similar to that
52 DISINFECTION AND DISINPUCTANTS.
of Geneste Herscher's (Fig. 16). It has been carefully studied by
Dr. Hahn.*
United States. — In the United States the apparatus of Geo. V.
M'Lautlin & Co., of Boston, is used to some extent, as is also that of
Washington-Lyons. M'Lautlin's machine bears a very close resem-
blance to Geneste Herscher's apparatus, the only appreciable difference
being that it is built in an apparently more substantial manner to
enable it to work with steam at a pressure exceeding 10 lbs. Generally
speaking, disinfecting apparatus on the Continent is built with rather
a different object in view to that which obtains in this country. It is
not regarded as essential for the clothes to come out absolutely dry ;
and if they have to be dried by some other means after treatment,
that is not considered prejudicial to the machine.
Time, also, is not valued to the same extent' as in this country,
whereas first cost is a matter of the greatest importance. As a
consequence, a cheaper machine is produced, which disinfects at the
expense of wetting the goods after a more prolonged exposure. These
conditions do not obtain generally in this country, for frequently,
owing largely to recent regulations, the whole of the clothing and
bedding of a family have to be disinfected and returned ready for use
within one or two hours, whilst the family is housed at the public
expense pending the chemical disinfection of their own room. The
public sentiment is also in favour of purchasing things of the most
durable nature, in spite of the fact that their first cost may.be greater.
Lastly, the use of low-pressure steam is not largely favoured, because
very bulky articles, such as bales, cannot be disinfected in machines
using it ; whereas, high-pressure machines can not only deal with the
bulkiest articles, but can always, if desirable, be used with low-pressure
steam with equal efficiency.
It is probably for these reasons that low-pressure disinfectors have
been tried, and very largely abandoned at home.
PUBLIC INSTALLATIONS.
Plan of a Disinfector House. — The main point which has not yet
been dealt with in this chapter is the arrangement of building and
appurtenances requisite for a public installation. Owing to the
courtesy of Mr. Rowland Plumbe, F.R.I.B.A., of London, the
drawings of the disinfector house and incinerator at present being
erected for the Vestry of St. Mary's, Newington, are shown in the
plate opposite. The particular arrangement is not one which must
be followed in every instance, for each case has to be treated on its
* DetUsch. Medic. Wochemch., 1890, No. 12.
V
DISINFECTION BY HEAT.
53
merits, and this building has had to be adapted to its environments.
It is, however, a fairly representative installation, arranged with
considerable care, and is complete, with the exception that the plan
does not show the sheds for the infected and disinfected vans or
hand carts, which have been subsequently erected.
The main feature of a disinfector house is that there shall be two
rooms ; one permanently kept for infected goods, and the other for
disinfected goods. The machine is built in the wall dividing the two
rooms, and is fitted with two doors, one door opening into each room.
These doors should never be open at the same time, and there should
be no direct inter-communication whatever. Two men should be
provided to work the apparatus, one of whom should have his duties
confined to the infected side, and the other to the disinfected side of
the apparatus. Generally, one man only is told off to look after the
Fig. 17. — Dr. Sergeant's incinerator.
infected side, where the boiler and things that require attention are
placed, and he signals or shouts to some man engaged on other work
when goods have to be moved from the machine into the disinfected
room. The incinerator is no essential part of the disinfection, but is,
nevertheless, sometimes put on the same site for the purpose of
destroying by fire bedding or clothing that is not worth disinfecting.
For instance, it sometimes happens that the mattress of cholera
patients are purposely of the commonest description, and only fit to
burn. They can only be burned in very carefully constructed furnaces,
fitted with a secondary fire to destroy the objectionable products of
combustion ; otherwise, the process might become a nuisance and
danger to the neighbours. They are also useful for getting rid of
condemned meat, offal, excreta, &c. A figure of Dr. Sergeant's
incinerator, which is the one adopted at Newington, is shown in Fig.
17. At Newington, the same chimney is used for both the disinfector
54
DISINFECTION AND DISINFECTANTS.
DISINFECTION BT HEAT.
5fr
66 DISINFECTION AND DISINFECTANTS.
boiler and incinerator, but otherwise the two departments are kept
distinct. The minor points to be attended to in the building for a
disinfector require also some care. The floor should be of some smooth,
hard material, such as cement, laid with a fall towards a drain ; and
arrangements should be provided for swilling out the two rooms very
thoroughly by fixing a small hose to taps in either room. All internal
angles should be rounded, so as to permit of ready cleansing ; and
slate and iron should be used where possible in preference to wood for
the racks and fittings. Good washing accommodation and w.c. should
also be provided for the attendant, and special overalls should be given
him for wear whenever at work in the building. These overalls should
be disinfected before allowing them to go to the laundry. Considerable
attention should be paid to the ventilation of both rooms, as in summer
the radiated heat from the boiler and machine is apt to be oppressive.
The lighting should also be ample and well diffused, for this encourages
cleanliness.
United States. — For the Marine Hospital Service of the U.S.
Government at the modern stations plant has been provided for
disinfecting by heat, by fumes, and by chemicals. The arrangements
have been described by W. H. Francis of Philadelphia,* and are
shown in Figs. 18 and 19. The disinfectors are two rectangular
steam -jacketted chambers 16 feet long, with steam-tight doors opening
at each end. The chambers are constructed of an inner and outer
steel shell, 2^ inches apart, cast-iron end frames, intermediate truss
bands, and of screw stay-bolt construction. The doors have concave
steel plates riveted to cast angle frames fitted with heavy rubber
gaskets, they are handled by convenient cranes, and drawn tight by
drop-gorged steel eye-bolts, swinging in and out of slots in the door
frames. The chambers, therefore, act as drying ovens, the articles
being heated before the admission of the steam, and thoroughly dried
after the steam has been exhausted. A vacuum of 15-20 inches can
be produced in the chamber before the admission of the steam, and
any pressures up to 15 lbs. (250° F.) can be obtained.
For fumigating at this station, 3 lbs. of sulphur per 1,000 cubic feet
of air space are employed, and for disinfecting with liquids, mercuric
chloride (1 : 1,000), carbolic acid, and chloride of lime, are at present
used.
* Proc. Am. Soc. Mech. Engineers, vol. xv.
CHEMICAL DISINFECTANTS. 57
CHAPTER IV.
CHEMICAL DISINFECTANTS.
THE NON-METALLIC ELEMENTS AND THEIR DERIVATIVES.
The halogens — Chlorine, chlorides, hypochlorites, chlorates — Bromine, bromides —
Iodine, iodine trichloride, iodic and periodic acids and periodates — Fumigation
— Fluorine, fluorides, silicofluorides — Chloroform, bromoform, iodoform —
Organic haloid compounds.
THE HALOGENS AND THEIR COMPOUNDS.
Chlorine. — About the year 1800, Guy ton de Morveau in France, and
Cruikshank in England, proposed the use of chlorine as a disinfectant.
Cruikshank suggested the following method of procedure : — *' 2 pts.
common salt, and 1 pt. powdered manganese, with 1 pt. water and
^ pt. sulphuric acid gradually added, is sufficient for five or six beds."
A similar method of generating chlorine is to gently warm one part
of manganese dioxide in a granular form with four parts of concentrated
hydrochloric acid (5 grms. MnOg and 20 grras. HCl give 1 litre of 01;
I oz. of MnO^ is abundance for a large room).* Letheby recommended
one teaspoonful of powdered manganese and half a cupful of strong
crude hydrochloric acid, mixed by degrees by stirring in a saucer set
on a hot brick.
It should be remembered that the crude acid contains arsenic,
which would be evolved as the intensely poisonous arsenious chloride ;
hence, at a little additional expense, pure acid only should be employed.
Each of these methods requires heat, which presents great difficulties
in application. Usually, therefore, the chlorine is evolved from chloride
of lime by the action of moderately diluted sulphuric or hydrochloric
acid. It has been stated t that 1 part bleaching powder with 2 parts
of sulphuric acid of specific gravity 1*53, and enough water to cover
the powder, evolved three times as much chlorine as when hydro-
chloric is used. This may be due to the heat generated by the
sulphuric acid, as the amounts yielded are theoretically the same,
as the following equations show : —
CaCljO + H2SO4 = CaS04 + HjO + Clj.
CaCljO + 2HC1 = CaCl, + HjO + Clg.
If the insoluble and, therefore, solid sulphate of lime keeps back less
chlorine than does the deliquescent calcium chloride, the difference in
the yield might be explained.
* Reichardt, Deain/ectionsmiltel, p. 65. i Lancet, 1888, p. 110.
58 DISINFECTION AND DISINFECTANTS.
Dr. Mehlhausen * of Berlin used 600 grammes of bichromate of
potash and 3 kilos, of pure hydrocWoric acid, of specific gravity 1"16,
for generating chlorine. These weights yield on warming 130 "6 litres
(405 grms.) of chlorine. He traced a somewhat greater activity to the
gas than when prepared by the ordinary processes ; this may, perhaps,
be due to some chromyl chloride (CrOgOlg) evolved in addition. The
cost of this method prevents it from being generally employed.
Chlorine has three possible modes of action : —
1. It may replace hydrogen in the organic substances, forming
innocuous compounds and poisoning the bacteria. Such action would
be slow, would scarcely occur at all except in sunlight, but yet would
be the only possible action on dry matter. It may account for the
antiseptic action of chlorine, as distinguished from its disinfecting
power ; the latter has been questioned, but the experiments of Baxter
and Sternberg on dried vaccine lymph seem to be conclusive.
2. The offensive gases of putrefaction are decomposed by chlorine ;
sulphuretted hydrogen, which is always present, being resolved into
sulphur and hydrochloric acid —
HgS + CI2 := 2HC1 + S.
Phosphoretted hydrogen from animal matter would be also decom-
posed. Ammonia (and compound ammonias) would give first of all
ammonium chloride and nitrogen —
8NH3 + 3CI2 = 6NH4CI + N2,
hence the copious white fumes frequently noticed when a chlorine
mixture is thrown into a dung pit. More chlorine decomposes the
ammonium chloride first formed ; when this takes place there is
always a formation of intensely acrid vapours which attack the eyes,
owing, no doubt, to the production of chloride of nitrogen. Hydro-
carbons would in most cases be little affected by chlorine, but they, as
a rule, are not so offensive as the other gases mentioned.
3. The common and most important action of chlorine is as an
oxidising agent. In the presence of water, more especially in light,
it combines with hydrogen to form hydrochloric acid, and liberates
oxygen —
HjO + CI2 = 2HC1 + O.
The oxygen so formed is far more active than atmospheric oxygen,
and is in a condition to burn up the putrescent matters and kill the
organisms which accompany the putrefaction. But there are several
conditions indispensable to thorough disinfection, and amongst these
(a) tJie presence of moisture is absolutely essential when chlorine fumi-
gation is resorted to.
* Bericht der Cholera Commission, 1879, vol. vi., p. 335.
CHEMICAL DISINFECTANTS. 59
(6) Qtuintity. — Baxter says that the disinfecting action of chlorine
and of potassium permanganate depend much more upon the nature
of the liquid than upon the specific organism present. Kuhn,
Bucholtz, and Haberkorn have confirmed this view. For example, in
a liquid like urine, which requires large quantities of chlorine, before
the liquid be deodorised, the action on germs does not begin before
the chlorine is in excess, and it must be maintained in excess until
the last germ is destroyed, otherwise the fermentation will recom-
mence. But if the action has been completed, germs that may
afterwards enter from the atmosphere find it an unsuitable medium
for growth. From this it follows that the smell of chlorine must be
perceptible and persistent for some time, or no good result will have
been obtained. Excess of chlorine may be chemically tested for by a
paper dipped in a solution of iodide of potassium and starch paste,
which is turned blue by free chlorine, or the bleaching of litmus paper
may be used as an indication.
Baxter in his experiments mixed chlorine with vaccine lymph, and
found that its activity was not destroyed till the liquid had become
acid from the presence of free hydrochloric acid. Most putrefactive
organisms thrive best in alkaline solution ; hence the antiseptic power
of all free acids in varying degrees.
To kill pure vaccine, Baxter found the minimum proportion of
chlorine to be 0*2 per cent, {i.e., soda chlorinata solution, B.P. 1 in 10 :
chloride of lime, 1 in 100, both acidified). Hofmann * gives 0'15 per
cent, as sufficient for septic virus.
(c) Time. — The vitality of the organisms considerably influence the
length of time required for sterilisation. Sternberg f found that
1 per cent, of chlorine in air in six hours made dry vaccine inert.
This is a very large quantity, for a room of 50 cubic metres would
require at this rate 5 kilos, of bleaching powder, even if all the
chlorine were evolved, which is generally impossible. Baxter states J
that air saturated with chlorine by standing over the aqueous solution
took thirty minutes to sterilise needles charged with dry vaccine.
These are impossible conditions in practice. Living organisms
themselves contain 90 to 95 per cent, of water, hence the disinfectant
entering them would be greatly diluted. Moreover, their envelopes
are often tough and resisting, especially those of germs. Therefore,
more time must be given.
Fischer and Proskauer,§ from laboratory experiments on spores of
* Viertdjakrsschrift fiir gerichtliche Medicin, April, 1878.
f Bulletin of the U.S. Board of Health, Washington, 1881.
t Report of Med. Off. of Privy Council on Dininfectanta, 1875.
§ Mitt, aus d. Kaiserl. Oesundheitsamte, Berlin, 1884.
60 DISINFECTION AND DISINFECTANTS.
anthrax and various bacteria, conclude that for air fumigation at
least 0"54 per cent, of chlorine must be present, and consider it more
efficacious than sulphurous acid. "The experiments of Jalan de la
Croix,* on the putrefying bacteria of beef tea, give a surprisingly
favourable account of the power of chlorine among the agents which
are fatal to low organisms, and place it next to corrosive sublimate as
an " anti virulent."
The substances tried, arranged nearly in their order of efficiency as
determined by him, were as follows : — Mercuric chloride, chlorine,
chloride of lime, sulphurous acid, bromine, sulphuric acid, iodine,
aluminium acetate, mustard oil, benzoic acid, sodium salicylate,
potassium permanganate, phenol, chloroform, borax, alcohol, oil of
eucalyptus, potassium chlorate. The methods used were first that of
Bucholtz, then those of Salkowski, Wernicke, and Wernitz, and other
specially devised " bacterioscopic " processes.! He concluded that
" besides chlorine, bromine, and iodine, we have only sublimate and
osmic acid that will kill the bacteria of splenic fever within twenty-
four hours."
Given the above time, he states as to quantity that " in beef tea
all growth is stopped by ] in 30,208 — i.e., 1 gramme of chlorine in
30 litres (chloride of lime, 1 in 11,135 has the same efiect) ; 1 in
22,768 kills bacteria in full" growth, and prevents their spontaneous
development in cooked beef tea exposed freely to air ; tliat of 1 in
15,606 in raw beef tea. Chloride of lime is required in stronger doses,
of 1 in 3,700 in cooked, and, contrary to what one would expect,
1 in 286 in raw beef tea."
To destroy the germs it requires yet larger amounts, varying
between 1 in 431 and 1 in 4,911 for chlorine, and 1 in 100 to 1 in
500 for chloride of lime.
Vallin J throws some doubt on the above researches, and asserts
that the antivirulent action of chlorine is relatively restricted, and is
notably inferior to what would be presumed by the above figures.
Dr. Mehlhausen§ made a number of experiments, of which the
following is an abstract : —
I. In a room of 37 cubic metres with door and window sealed, he
placed a number of insects in gauze enclosures, and two vessels of
water teeming with vibrios, rotifers, and infusoria. An earthen pot
containing 740 grammes (20 grammes per cubic metre) of bleaching
* Arch, far experiment. Pathologic, 1881.
t Wernitz, Grundrias der Desinfectionslehre, pp. 166 to 178, and Virchow's
Archiv., voL Ixxviii., pp. 53 to 60.
t Traits des Disinfectants, 1882, p. 118.
%Bericht der Cholera Commission, 1879, vi., p. 335.
CHEMICAL DISINFECTANTS. 61
powder with a little water, to which he added 1,100 grammes of hydro-
chloric acid, was also introduced and the door sealed. After nine
hours the room was opened and ventilated. The animals were all
living ; the flies only were insensible, but recovered on the next day.
The water in the vessels, originally neutral, had become acid, and
gave with nitrate of silver a copious precipitate of chloride. All the
bacteria were dead. The 740 grammes of chloride of lime had given
59*7 litres of chlorine — i.e., 1-613 litre per cubic metre, or 01613 per
cent, in the air (about the amount mentioned by Hofmann, as above
given), whilst some had been undoubtedly wasted by non-evolution
and by leakage.
II. With the same conditions as before, but with double the amount
of chlorine. The vessel contained fermenting urine. In eight hours
there was much residual chlorine. Most of the higher organisms were
killed ; the urine had become acid, but the bacteria and spirilla were
still moving.
III. Equal parts of common salt and manganese dioxide, with
2 parts of sulphuric acid and 1 part of water, were warmed together,
whilst putrid urine and dysenteric stools in wide flat dishes were
exposed for twenty hours to the gas. On opening, only a feeble odour
of chlorine was noticed, as it was masked by the effluvia from the
stools and urine. Some of the organisms were only benumbed, and
recovered their activity in fresh air. The liquids were very acid, and
had not entirely lost their fetid odour.
IV. In another room of 48 cubic metres a glass balloon was placed
containing 600 grammes of bichromate of potash and 3 kilos, of hydro-
chloric acid of specific gravity 1-16 ; by warming, 405 grammes of
chlorine were evolved, equal to 2*7 litres per cubic metre, or 0-27 per
cent. Under these conditions all the organisms were killed, but the
time required was not stated. The process is, however, long, expen-
sive, and somewhat diflicult, costing about 4 centimes per cubic metre,
or about Is. 6d. for disinfecting a room 11 feet square.
Vallin points out that fumigations with chlorine are of little advan-
tage, and are decidedly inferior to those with sulphurous acid. The
disengagement of chlorine is incomplete, unless stirred and heated
constantly, which is almost impossible in ordinary practice. The
facility of '* sulphuring " is, on the other hand, of the greatest value,
and the expense is about four or five times less.*
Jeannel t noticed that chlorine seemed to have only a temporary
action on certain vibrios, as he was able by means of ammonia to
restore them to activity after they had been subjected to the influence
of chlorine for a long period.
* See Sulphurous acid, later. i Union Midicale, Sept. 28, 1871»
62 DISINFECTION AND DISINFECTANTS.
The experiments of Sternberg* concerning the action of chlorine
on infusoria and micro-organisms show that the resistance of the latter
is considerable. In an experimental room of 10 litres capacity, he
placed 28 grammes of chloride of lime. It was an hour and a half
before the movements of the bacteria contained in a drop of putrid
meat infusion ceased, although the watch glass holding the liquid was
directly exposed to the gas. (If he did not acidify, the only chlorine
evolved would be that liberated by the small quantity of carbonic acid
in the air present — namely, about 0*071 per cent. — which is too small
a proportion, if we take Hofmann's minimum of 0'16 per cent., or
Baxter's 0*2 per cent, be admitted.! But the total amount would still
be immense if it could be absorbed by the drop of fluid, as it would
reach 7 grammes of chlorine in the 10 litres of air.) Sternberg did not
consider the movements definitely destroyed until after an hour's
exposure to fresh air, they had not reappeared.
Dr. Cash | subsequently studied the action of chlorine, and en-
deavoured to determine the comparative value of the halogens and of
sulphurous acid in destroying the virus of anthrax and tubercle ; he
concluded that the halogens do not present any great difierences when
employed in solutions, the strengths of which are proportional to their
atomic weights, though chlorine was the least active and iodine the
most. This would oblige us to use 127 parts of iodine for 80 of
bromine and 35*4 of chlorine. He found that when employed in
dilute solutions they did not disinfect. (That is, below Baxter's limit
of 0*2 per cent.) He prefers sulphurous acid if the disinfecting agent
be employed as a gas, but considers it better to employ a solution of
the gas if possible.§
(d) Contact. — Intimate contact between the gas and the centre of
infection must be assured. If large masses of putrescible matter like
faeces are present, chlorine gas fails in its action, and must be supple-
mented by the addition of metallic salts, &c. For if all easily de-
composable organic matter be not destroyed, a recommencement of
putre&ction is not prevented. ||
Klein II used chlorine fumigations in stables for disinfection from
swine plague with success.
When in great mass — e.g., dung and straw in typhus — care must be
taken not to give a false security by illusory means. Probably in many
cases it is better to rely on purification being accomplished naturally
• Bulletin of National Board of Health, Washington, July 23, 1881.
t See later, under Chloride of lime.
XPharm. Joum., 1S87, p. 485 ; L. O. B. Sixteenth Annual Report.
% See later, Sulphurous Acid. || Reicbardt, Desin/ectionamittel, p. 57>
IT L. O. B. Thirteenth Annual Report.
CHEMICAL DISINFECTANTS. 63
by air and moisture than run the risk of natural decomposition being
retarded by the employment of inefficient quantities of antiseptics.
It must be remembered that manure that has been treated with
chlorine or chloride of lime loses all its agricultural value on account
of the destruction of its ammonium salts. On the other hand, if
chloride of lime is sprinkled over faecal matter before removal, it
destroys any offensive gases that may be evolved.
It cannot be too strongly emphasised that air cannot be disinfected
and still remain fit to breathe. Wernitz * condemns all fumigations
as useless, classing all methods as "illusory specifics," since " we
require a body which shall come in intimate contact with atmospheric
dust, and act for a long time on it." Vallin says " disinfection of air
is useless and gives a deceitful security. To make a strong odour of
phenol, or put a basin of chlorine in a corner, is, with regard to de-
struction of virus, an operation quite futile, as the virulent particles in
air are probably protected by an envelope of dried albuminous matter."
Chloride of Lime and Hypochlorites. — By treating the alkalies and
alkaline earths in solution with chlorine in the cold, mixtures of
chloride and hypochlorite are formed which have been long known as
useful disinfectants.
Liquor sodse chlorinatse, B.P., chlorinated soda, or " Eau de
Labarraque " has a strength of 2^ per cent, of available chlorine. It
is used in surgery diluted with 10 parts of water (equal to Baxter's
effective strength of 0*2 per cent. CI) as an antiseptic lotion, and is
refreshing and non-irritant. By its decomposition it produces a small
quantity of common salt. It has also been employed as a mouth wash.
"Eau de Javelle," introduced by Percy in 1793, is similarly made,
but with potash instead of soda, and is said to keep longer than the
soda compound. The orders of the French Prefecture recommended
1 part of Eau de Javelle of 18° Baume to 100 parts of water for
flushing closets and washing walls, &c. It has the advantage over
" chloride of lime " that it does not leave behind a deliquescent body
like calcium chloride. It acts similarly to chlorine.
" Chloride of lime" or bleaching powder, obtained by passing chlorine
over moist slaked lime, has the advantage of being a dry powder, which
is more easy of transport and keeps better than the soda and potash
preparations. It is a mixed chloride and hypochlorite of the formula
CaCljO, and breaks up into chloride and hypochlorite on solution in
water. The latter is strongly alkaline, and is acted on by the carbonic
acid of the air giving carbonate of lime and hypochlorous acid.
2CaCl,0 = CaClj + Ca(C10)j
Ca{C10)j + COj + HjO = CaCOa + 2HC10
♦ Desin/ectiontlehre, 1882.
64 DISINFECTION AND DISINFECTANTS.
In contact with organic matter tlie hypochlorous acid splits up into
hydrochloric acid and oxygen, and it is on this liberated oxygen that
its value as a disinfectant depends^ The calcium chloride remains
behind as a deliquescent salt, and this is an objection to bleaching
powder being mixed with lime for white washing, as the surface
remains damp. It is important to remember that chloride of lime
must be acidified, either slowly and spontaneously by the carbonic
acid, or by the addition of hydrochloric or sulphuric acid or even
vinegar, for any chlorine to be liberated. Weak acids only decompose
the hypochlorite, leaving the chloride untouched, and evolve hypo-
chlorous acid. Strong mineral acids, on the other hand, evolve
chlorine.
To prove the necessity of acidification, D'Arcet and Gaultier de
Claubry showed that air deprived of carbonic acid by a potash wash-
bottle, and then passed over chloride of lime, was not disinfected.
Good bleaching powder contains 34 per cent, of available chlorine.
It is best used in the proportion of 1 part to 10 or 12 parts of water.
It should be freshly prepared, and kept from light and air. When old
it becomes damp and is then of inferior value.
Similar preparations of aluminium and magnesium hypochlorites have
been made by precipitating a solution of chloride of lime by sulphates
of aluminium or magnesium. The latter has no special advantage,
but the former has in addition the mordanting and clarifying and
antiseptic properties of other aluminium salts (see Chloralum, p. 131),
and might deserve more extended use. It is commercially used
for bleaching paper pulp, under the name of Anderson's solution. The
American " standard solution of chloride of lime " is thus described : —
" Dissolve chloride of lime containing not less than 25 per cent, of
available chlorine, 6 ounces to 1 gallon of water (4^ per cent.). Use
1 quart for each discharge in cholera, typhoid, &c. Mix well, and
leave in the vessel at least one hour before being thrown away." *
For disinfecting clothes, the diluted Eaux de Javelle or Labarraque
are better than chloride of lime. The fabrics must be washed soon
after, or the fibres will be rotted. Of course the colours will be more
or less afiected. Jaeger used a paste of equal parts of water and
bleaching powder for disinfecting tuberculous sputa, t
It must be remembered that chlorine and the hypochlorites also act
energetically on other substances, so that any mixture of them with
other disinfectants can only be endorsed by an experienced chemist,
for, as a rule, these are only to be used apart.
* Report of Committee on. Disirfectantii of American Public Health AsaocicUionf
p. 235.
t Arb. a. t/, Kais. Gesundh., 1889.
CHEMICAL DISINFECTANTS. 65
One part of chloride of lime to 100 of water forms a liquid for
washing the person in infectious diseases. The odour is most per-
sistent, and may even convey a false sense of safety when tlie effective
limit has long been passed. Semmelweis, however, in 1846 succeeded
in stamping out of Vienna endemic puerperal fever by its use, and Sir
Spencer Wells has advocated its use in this country, *
Liebig contended that the continued action of chlorine or hypo-
chlorites, as in the wards of hospitals, leads to lung diseases in the
patients and attendants. Pettenkofer and Lehmann t say that 0*001
to 0*005 per cent, of chlorine affects the respiratory organs ; 0*04 to 0*06
per cent, produces dangerous symptoms ; and over 0*06 per cent, soon
proves fatal. Undoubtedly chlorine will cause chronic bronchitis if in
quantity, and disinfection with chlorine involves such a percentage of
the gas as absolutely necessitates the removal of animals and plants
from its vicinity.
The Berichte der Choleracommission des Deutschen Reiclies, 1879, con-
demns the use of chlorine as being dangerous, and Koch obtained
unsatisfactory results with chloride of lime. J
The same, however, is the case with sulphurous acid, nitrous gases,
and still more with bromine and iodine, which are all intensely
I)oisonous. § This action, coupled with the fact that the gas corrodes
metal fittings and rots fabrics, has led in great part to its disuse for
this purpose, and to its utility being confined to the disinfection of
sewers and closets. Angus Smith, || on the other hand, points to the
healthy appearance of men employed in bleaching factories ; he attri-
butes this to the purification of the air. Notwithstanding these
objections to its use, chlorine must be regarded as the most powerful
of the disinfectants, being the only convenient gaseous body that can
quickly destroy organic matter and consequently ensure perfect disin-
fection.
" Chlorozone," a mixture of hypochlorites and permanganates, was
formerly advocated. It was probably made by passing a current of
chlorine through milk of lime, or a solution of soda or potash, in
which finely ground manganese dioxide was suspended, or to which
the manganous residues from the manufacture of chlorine were added.
The chlorine oxidised the manganese compounds to permanganate, and
at the same time formed hypochlorite. Such a solution would be
attractive from its crimson colour, and would at the same time combine
the oxidising properties of both these agents.
* B. M. J., 1892. + Munich Acad., 1887.
J Milt. a. d. KaU. GeJttmdh., vol. i., 1881.
§ Wirkung der verdunnten Lufl a. d. Organ. Friiukel Sc. Goppert, Berlin, 1883.
II Disinfectants and Disinfection, 1869, p. 49.
5
66 DISINFECTION AND DISINFECTANTS.
Chambei'land and Fernbach, in a paper on the " Disinfection of
Public Places and Dwelling Rooms,"* state that eau de Javelle,
bleaching powder of a concentration of 1 in 120, and commercial
peroxide of hydrogen, are found to be strongei* disinfecting agents
towards pathogenic microbes than a 1 per cent, solution of mercuric
chloride. These antiseptics, however, at the ordinary temperature, do
not act at all on moist germs, or only do so after several hours.
When heated to 40° or 50° C, or higher, moist germs are destroyed in
a few minutes. Therefore, for rooms they must be heated. Dry
germs can resist their action for several hours at 40° or 50° C, but if
then moistened with water they are destroyed. It is noteworthy that
a 0"8 per cent, solution of bleaching powder is far more active than
1 in 120, whether for moist or dry germs, or whether hot or cold.
Thymol, lysol, oil of turpentine, are, in comparison, bad antiseptics.
In their experiments 100 grammes of bleaching powder were triturated
with 1,200 of water, allowed to stand one hour, filtered, and diluted
with 10 litres of water.
This paper requires a few observations. Warming very easily
converts "chloride of lime" into chloride and chlorate, and renders it
almost inert as a disinfectant; it decomposes peroxide of hydrogen into
water and oxygen, so rendering it useless ; eau de Javelle (potassium
hypochlorite) similarly suffers ; hence great judgment would be
required in the operation. It must be remembered that the
alkaline hypochlorites do not evolve chlorine until after they are
acidified, so that a strong alkaline solution may be less efficient
than a weaker one in water, since the carbonic acid of the large
quantity of water liberates a greater amount of hypochlorous acid.
With reference to the prescription for chloride solution for practical
purposes, an hour is not necessary if well agitated, and filti*ation is
superfluous.
Sheridan Delepine t uses chlorinated lime for disinfecting rooms
which have been contaminated by tuberculous patients, as follows : —
(1) A solution of chlorinated lime (1 in 100) should be prepared;
(2) the walls, ceiling, and floor should be washed with this solution in
the same way as lime or whitewash is usually applied ; (3) this process
should, for safety, be repeated three or four times in succession ;
(4) the room should then be closed, a small safe petroleum stove being
first placed in the middle of the room, and precautions taken to prevent
any chance of fire ; over this stove, a large tin basin fuU of water or
bleaching powder solution should be placed. To secure acidity to the
air, he further suggests suspending in the water bath a capsule
containing hydrochloric or acetic acid. Three hours is suflicient time
♦ Ann. de VInstitut Pasteur, 1893, vol. vii., p. 433. t MecU Chron., May, 1894.
CHEMICAL DISINFECTANTS. 67
foi' an ordinary room, and 6 ozs. of bleaching powder, using 3 pints of
water for each washing, is the quantity lie recommends.
W. E. Crow and Frank Browne, at Hong Kong, during the plague
in 1894, used free chlorine generated from ^ lb. chlorinated lime,
mixed with 1 quart of water and 1 quart of dilute sulphuric acid (1 in 5).
This quantity was used for each room.
The ^^ Her mite" or Electrolytic Process. — About 1859, Charles "Watt
discovered that when a solution of a chloride of the alkalies or alkaline
earths was electrol^'sed, a solution similar to bleaching liquid was
formed. It presumably contained chlorides and hypochlorites, but
apparently was more active than a solution prepared in the ordinary
way. Magnesium chloride was said to be preferable. Such a solution,
originally intended for bleaching paper-pulp, has recently been
advocated by M. Hermite for sanitation, and sea-water, containing as
it does the chlorides of sodium, calcium, magnesium, and potassium, is
proposed as a cheap and suitable mateiial. He uses a special form of
"electrolyseur" for affecting the electrolysis, and proposes to pump the
solution through a system of pipes to the place of use, and thus render
it available for domestic use, and for local flushing of sewers, latrines,
&c. Dr. Piton's report to the Mayor and Corporation of Brest, refer-
ring to experiments on this system at Nice, states that the Hermite
solution, diluted to a strength of about \ gramme of free chlorine per
litre, does sterilise the fa?cal matter in the sewers, but that, in spite of
the rapid absorption of chlorine, the disintegration of paper and fjecal
matter is no more rapid than when ordinary water is employed. The
system was tried at Worthing in the early part of 1894, and Dr. C.
Kelly, the medical officer of health for Worthing, in a report incor-
porating the chemical and bacteriological analyses by Dupre and
Klein, " dismisses the experiences of the trials made by the Worthing
Corporation as having failed to realise the claims of the inventor,
besides involving serious considerations of expense, both in the
production of the fluid and the method of applying it to houses."
This report was questioned by the English agents, Messrs. Paterson.
«fe Cooper, who have formally protested. Dr. Riifier and Sir H. Roscoe
have reported more favourably on the process, and it has been further
tried at Havre, I'Oriente, and Nice.
In the patent of Hermite, Paterson k Cooper, No. 22,279, 1893,
the apparatus is described, and the strength of the fluid obtained is
stated to be 2 grammes of free chlorine per litre, and for use it is
recommended to be diluted six or seven times. A current of 300
amperes at a pressure of 6 volts is required to decompose the sea
water in the electrolyseur. In patent No. 6,495, March 31, 1894, a
method of protecting the iron pipes from corrosion by the chlorine is
covered.
68 DISINFECTION AND DISINFECTANTS.
The Lancet Report on the Hermite process and the experiments at
Worthing * comes to the following conclusions : — ■
By electrolysis of the magnesium chloride in the sea water, magnesia
and chlorine jire liberated, which subsequently combine to form
magnesium hypochlorite Mg (OCl)^ and magnesium chloride. This
liquid may be regarded as the magnesian equivalent of bleaching
powder solution. The magnesium hypochlorite dissociates into
magnesia, which deposits on the walls and floor of the electrolyser,
and free hypochlorous acid, which remains in solution.
Mg(0Cl)2 + 2H2O = Mg(0H)2 + 2H0C1.
The Hermite solution then practically resolves itself into a dilute
solution of hypochlorous acid, and may be cheaply imitated by passing
carbonic acid through a solution of ordinary bleaching powder. It is
admitted, however, that this "artificial Hermite" gave in bacterio-
logical examination " varying results, and could not be depended on
to exert constantly an equivalent action to the Hermite solution."
Chemically, however, the two solutions exhibited very close resem-
blance.
The strength of the electrolysed sea water in chlorine, or its equi-
valent, as determined by the arsenious acid process t is 0-5 gramme
•CI per litre. Urine at once acts on it, depriving it of about half its
chlorine strength.
In comparative experiments on the action on ordinary stools of
Hermite fluid, bleaching powder solution, and milk of lime 2i and
I per cent., it was observed that, as expected, the bleaching powder
was not so immediate in its effect, but in a longer period the final
result was similar. " Although in consequence of this the bleaching
powder does not exert so rapid and immediate effect as the more un-
stable Hermite solution, yet the weaker solutions of the former, owing
to their stability, in the end produce a much more complete process of
sterilisation than in the case of Hermite solutions of similar dilution."
The action of the full-strength Hermite fluid on the pathogenic organ-
isms of diphtheria and of cholera, and the Staphylococcus pyogenes
aureus were very satisfactory ; but in the case of anthrax it was less
conclusive, as the cultures used were proved to be somewhat feeble.
Both gelatine plate and broth cultivation were tried. It was far more
efficacious than even strong solutions of phenol. As compared with
mercuric chloride, the rei)ort gives the preference to the Hermite fluid
as a practical disinfectant. It sees, however, no advantage in the
Hermite solution over the product obtained by treating chloride of
lime in solution with carbonic acid.
* Lancet, May 26, 1894. t Methods rf Anali/sis, Chap. xv.
CHEMICAL DISINFECTANTS. 69
Sir Henry Roscoe and Lunt have also criticised the Hermite process
unfavourably.*
Chlorates. — Being more stalile than the hypochlorites, the chlorates,
although they contain more oxygen, give off neither oxygen nor
chlorine unless a strong acid be added. Such a mixture is a very
strong oxidant, but it evolves besides chlorine, more or less of the
explosive and poisonous chlorine oxides known as " euchlorine."
Wiederhokl recommends cholera excreta to be treated with potas-
sium chlorate and hydrochloric acid. The odour of the gases evolved
is very unpleasant, and powerfully attacks the eyes. The action is
very rapid, but is soon exiiausted ; an objection which, independent
of cost and unpleasantness, renders other preventives preferable, t
By themselves, chlorates are mildly antiseptic. Dr. O'Neill found ^
that the chlorates of potassium and sodium had no preservative action
ou beef tea. Perchlorates are similar. §
Hydrochloric Acid. — Since almost all bacteria grow best in neutral
or alkaline solutions, and many are killed by even weak acidity, the
mineral acids are valuable disinfectants. Davaine|| states that the
virus of anthrax or septic fever is definitely destroyed by the following
proportions of acids : —
Anthrax.
^ Septicajmia.
Hydrochloric,
Sulphuric,
Chromic,
1 in 3000
1 „ 5000
1 „ 6000
1 in 1500
1 „ 3000
Vallin, from his own experiments, thinks that a larger amount is
required.
Acid fumigations for disinfection, especially with hydrochloric acid,
•were introduced by Guy ton de Morveau in 1805. Previously, in 1773,
the stench from the catacombs under the church of St. Etienne at
Dijon (which, of course, would be very ammoniacal) was entirely
removed in twenty-four hours by pouring 2 lbs. of sulphuric acid on
6 lbs. of salt in a vessel heated by a brazier of hot cinders.
NaCl + H2SO4 = NaHSO* + HCl.
The next year the hospital at Dijon, where typhus was raging, was
successfully disinfected by the same means. After several other trials,
this process was strongly approved by the Academy of Sciences. For
350 cubic metres of space, 200 grms. of salt and 240 grms. of sulphuric
acid of 60° B. were recommended.
* Journ. Soc. Chem. Ind., 1895. f Reichardt, Deslnfectionsmitlel, p. 95.
*Army Medical Report, 1872, p. 202. § Compare Periodates, p. 76.
II "Virus de Septicemic," Gaz. Med., Jau. 10th, 1874.
70 DISINFECTION AND DISINFECTANTS.
Its penetrating power and solubility, combined with cheapness and
facility of employment, are its chief merits. The gas is less irritant
than chlorine, but has a powerful pungent odour. Although it is now
seldom used, it is well worth further experiment. Guyton de Morveau*
states that " Dr. Cabanellas, in the terrible epidemic in Andalusia in
1780, having exposed to the simple vapour of hydrochloric acid for 16
days, pieces of very fetid flesh, there remained not the slightest odour
of putrefaction."
Against its employment are the experiments of Pettenkofer and
Lehmann, t in which animals exposed to 3*4: per cent, of the acid
in air for one and a-half hours were seriously affected, and many died.
Strong men can only stand 0*5 per cent, for a short time, and the
limit for workmen used to it is O'l per cent. Recent experiments
have shown that less than this is destructive of a large number of
pathogenic bacteria.
Chlorides. — Many of the chlorides have marked antiseptic properties.
Those of the heavy metals, such as iron, aluminium, and zinc, will be
noticed under the respective metals.
Sodium chloride, common salt, is generally employed for the preser-
vation of meats, butter, &c. This it does less by its own antiseptic
power than by removing in the brine the soluble and more puti'cscible
organic constituents, and by hardening the remaining insoluble fibres.
The brine becomes sometimes contaminated with ptomaines, and para-
sitic low organisms are produced. M. Goubaux has shown that it can
sometimes acquire a high degree of toxicity. However, it is genei'ally
thrown away and the meat washed before use.
Sodium chloride is not a disinfectant. Pringle, who was one of the
first to introduce direct experimental methods in the study of disin-
fectants, in his Memoire sur les Substances septiques et antiseptiques, X
which is of classical interest, and contains details of a series of most
carefully devised experiments, found sodium chloride so weak an anti-
septic that he placed it the lowest in his scale of bodies investigated.
In further experiments he proves that sodium chloride more frequently
hastens putrefaction, for, in the proportion of 10 to 20 grains to 2 grains
of beef and 2 ounces of water, the salt softens and dissolves the meat,
and "by a septic virtue favours its digestion." He cites other authors
who have admitted the " putrefiant " nature of sodium chloride.
Bouley,§ and Arloing, Coi'nevin & Thomas |] find that even a satur-
ated solution of salt is without action on the virus of anthrax.
Bromine. — Bromine, formerly employed by Ozanam to combat the
development of false membrane in diphthei'ia, is likely to be more
* Traits, 1805. t Munich Acad., 18S7, 179. X Acad, des Sciences, 1750.
% MMiclne VHerina'ire, p. 467. \\Lyon Hedical, June, 1882.
CHEMICAL DISINFECTANTS. 71
generally used as a substitute for chlorine in the event of an increase
in tlie demand for a volatile liquid which easily gives off, when
exposed, large quantities of potent gas. It is now made in large
quantities and comparatively cheap. Its odour and action on the
mucous membranes are worse than those of chlorine. According to
Pettenkofer and Lehmann, men cannot stand more than '002 to "004
per cent, unless habituated to it ; if so, not more than 0*01 per cent.
This shows that fumigation with chlorine or bromine in presence of
men or animals is of no value, since bacteria require 3 per cent. CI for
three hours, or 0*4 per cent, for twenty-four hours ; hence it can only
be used under the direction of experts. It is also intensely corrosive.
The chemical action is similar to that of chlorine, but slower. It is
much more soluble, bromine water containing 3 per cent, of the ele-
ment, and possessing greater stability than chlorine water. Bromine
stands intermediate in power between chlorine and iodine, as its
atomic weight would indicate. Wernitz * finds its efficiency against
diflferent known organisms varies between 1 in 1,000, and 1 in 2,840,
and 1 in 31,100, iodine lying between 1 in 1,000 and 1 in 24,000.
Jalan de la Croix,f to kill bacteria in beef tea, required of bromine,
1 in 2,550, of iodine 1 in 2,000 ; to sterilise the germs required,
bromine 1 in 336, iodine 1 in 410. To prevent growth in raw beef
tea exposed to air, 1 in 5,600 of bromine, 1 in 2,010 of iodine.
"Wilson X states that bromine water of 2 per cent, strength destroyed
Bacillus anthracis in one day.
Bucholtz § finds the growth suppressed by chlorine, 1 in 25,000 ;
iodine, 1 in 5,000 ; bromine, 1 in 3,333, as compared with sulphur
dioxide, 1 in 666. Arloing, || confirmed by Koch, finds that bromine
is the most powerful of all destructives to the virus of anthrax and
tubercle ; even killing the dried virus, upon which chlorine does not
act. To summarise, 4 parts of bromine appear to be about equal to
5 parts of iodine, and a safe minimum is about 1 in 2,000, or com-
paratively —
CI 0-02 per cent. Br 0*05 per cent. I 0-062 per cent.
The Prussian Government ordered (March 13, 1879) that when
strong disinfection of stables was necessary, after removal of the
animals, for every 18 cubic metres of space a flask of 250 grammes
of bromine should be planted in shell-sand, iron articles being as far
as possible removed, and doors and windows closed. The flask is
upset, and the operative quickly retires.
After twenty-four hours the place is opened, and ventilated for
* Wirhtng der Antiseptica, Inaug. Dissert., Dorpat, 1880.
t Verhallen den Bakterien, Archiv.f. exp. Pathol., 1881. :J: Hygiene, 1892, p. 525.
• § Archiv.f. exp. Pathol., vol. iv., pp. 1 to SO. I! Lyon Medical, 1882.
'2 DISINFECTION AND DISINFECTANTS.
twelve hours before the stable is again used. Its cost was then about
2^d. per cubic metre, but since that date the price of bromine has
been much reduced.* All the bromine would be used without
attention, and the method seems to have the merit of neatness and
efficiency.
Dr. Franck, to whom many of the improvements in the manufacture
of bromine are due, has introduced under the name of bromuni
solidijicatum, a very convenient form.f This is made by first forming
porous rods of kieselguhr (infusorial sand), and molasses baked until
hard, and then saturating them with liquid bromine. Each stick
contains about 75 per cent. Br by weight, so that a given weight of
disinfectant can be obtained by using the necessary number of sticks.
At present, however, they cost much more than ordinary liquid
bromine.
Fischer and Proskauerj have made a number of experiments with
the halogens. For bromine, a stoppered bottle was filled with
siliceous earth saturated with bromine ; when required the stopper
was removed, the bottle placed near the ceiling of the room, and the
vapour allowed to diffuse. They prefer chlorine, on the ground that
bromine is dearer and more destructive to cotton and wool.
They also draw attention to the importance of the presence of
moisture when the halogens are used as disinfectants.
A mixture is made by Messrs. May tk Baker, of Battersea, London,
consisting of a soluble bromide and bromate (preferably of sodium or
potassium) mixed with an alkaline bisulphate, such as NaHSO,j. The
addition of a small quantity of a terpene, essential oil, camphor, or
hydrocarbon increases the keeping power of the disinfectant. This
mixture, when moisture from the air is absorbed, liberates the halogen
thus : —
5NaBr + NaBrOg + eNaHSO* = 6Na2S04 + SHjO + SBrg.
It is known under the name of " Bromidine."§
The bromonaphthalene night-lights, which owe their efficiency to
the liberation of this element, give off the bromine only when
burning. II Dr. C. R. A. Wright has patented the use of monochlor- or
bromnaphthalene dissolved or suspended in solution of resin soap\.
He also proposed using these compounds in powders by mixing them
with sawdust or plaster of Paris, «fec.^
* Compare Mehlhausen's experiments with chlorine, ante, p. 61.
t Patent No. 254, 1883.
t Mitlheilungen aus clem Kaiserlichen Gesundheitsamte, Berlin, 188i.
§ Journ. Soe. Chem. Industry, 1887, p. 378 ; W. D. Borland, patent No. 6191,
1886.
\\ Journ. Soc. Chem. Industry, 1890, vol. ix., p. 407. H Patent No. 4,950, 1893.
CHEMICAL DISINFECTANTS. 73
Iodine is a less powerful disinfectant, according to Koch, than
chlorine or bromine. His experiments have the objection of having
been performed with an alcoholic solution of iodine, while both bromine
and chlorine were used in aqueous solutions. Cash's more recent
work shows that when used in rates proportional to the atomic
weights, iodine is more energetic than chlorine, bromine being inter-
mediate in its character.
Iodine water is practically stable, but is much weaker than bromin^e
water. Its vapour is eight and a-half times heavier than air, and,
therefore, difficult to diffuse.
Iodine does not act by oxidation like chlorine and bromine, but
directly combines with the protoplasmic matters of organisms, thereby
poisoning them. It is not a good deodorant, and has the disadvantage
of producing brown or blue stains when organic materials come into-
contact with it. Its high atomic weight (127) adds to its cost, but,
being a solid, it is convenient, safe, and portable. Lamps of various
kinds have been devised for vapoi'ising and diffusing it in a finely
divided state.
Messrs. Casson and Brown proposed using candles containing iodine
and salicylic acid incorporated with the wax. These, when burnt, give
off vapours of iodine and phenol. If the combustion is too free, iodine
alone is volatilised, the phenol being decomposed. These candles are-
said to remove all odour of sulphuretted hydrogen and tobacco smoke,
and are recommended for asthma, hay fever, <kc.
Better than these are the "Sussex patent night-lights," in which
iodoform is mixed with the wax. In burning, hydriodic acid is-
probably lil>erated first, and then decomposed by the heat into-
hydrogen and iodine.
Watson &, Fulton* have proposed candles containing iodine and
sulphur, which profess to give off the vapour of iodine and sulphur
dioxide gas, with no hydriodic acid.
A. J. Shilton f has taken out a patent ;J: for a solution of iodine
dissolved in an alkaline iodide in the proportion of 1 oz. of iodine and
2 ozs. of potassium iodide to 1 gallon of water ; also § a mixture of
2 ozs. potassium iodide, 1 oz. iodine, and 16 ozs. ammonium chloride >
these in strong solution are diluted with 15 to 20 parts of water, and
diffused into the room by a spray producer. Davaine and Marchal
de Calvi were the first to propose iodine as an antiseptic. The former
found that 7 milligrammes of iodine sufficed to kill anthrax bacilli in.
1,000 of liquid.lj Griffiths H states that 1 milligramme of iodine ia
* Patent No. 10,876, 1S85. f Joum. Soc. Chem. Industry, 1890.
X Patent No. 2,537, 1889. § Ihid., 1885, p. 239.
II Bui. de I' Acad, de MMecine, July 27, 1880.
^ Proc. Roy. Soc. o/Edin., vol. xv., p. 37.
74 DISINFECTION AND DISINFECTANTS.
100 c.c. of nutrient broth (1 part in 100,000) destroyed the vitality of
Sarchia lutea, a chromogenous coccus, in half an hour.
Dr. Williams asserts that iodine greatly reduces the number of
tubercle bacilli and prevents spore-formation. " We can inject with
im2)unity into the blood of a dog, for each kilogramme of body weight
-02 or "03 gramme of free iodine dissolved in 2 parts of .sodium iodide.
This for an ordinary man would be 1*4 to 2*1 grammes. Beyond this
it is poisonous, and death occurs in tw^enty-four hours. Potassium
iodide has an injurious action on the heart." * The importance of these
results is shown by the consideration that disinfectants externally
applied cannot arrest the progress of disease germs already established
in the body, since, as Koch says, " before they destroy the parasite,
they kill the host." The choice lies between real though dangerous
disinfectants like chlorine, and antiseptics like carbolic acid which
require to be of such strength as to be expensive and almost inapplic-
able. Prophylactic treatment, like injection, or Pasteur's and Koch's
inoculation, would have to supplement effective disinfection externally.
Koch states that to check Bacillus anthracis in man, by internal treat-
ment, 1 2 grammes of iodine must be constantly in circulation.
Iodine inhalation has proved valuable in phthisis and other lung
•diseases. Of course, it is very irritant if too strong, but a diluted
vapour is tolerated. f
Iodine Trichloride, ICI3, was proposed as a disinfectant by von
Langenbach. It occurs in orange-yellow needles, easily soluble in a
moderate quantity of water to a colourless acid solution of extremely
irritant odour, affecting the eyes. It is best kept as a 5 per cent,
solution. A solution of 1 in 1,000 keeps for several days; after a
time it decomposes in the presence of water into hydrochloric and
iodic acids, and loses much of its power. It is easily made by passing
a current of chlorine through water in which iodine is suspended with
constant agitation. It is well known in oi'ganic chemistry that the
presence of a trace of iodine favours greatly the action of chlorine on
organic bodies, hence it is not improbable that a small quantity of
iodine, or of its chloride, might be a valuable adjunct to chlorine dis-
infection. Von Langenbach pronounced iodine trichloride to be one
of the most powerful disinfectants known, an aqueous solution con-
taining from 0-67 to 1 gramme per litre, being as powerful as a 4 per
cent, solution of phenol. It can be used for cleaning the hands and
instruments, and ranks next to mercuric chloride as a germicide.
Traugott + finds by experiments on hospital patients that it is not
poisonous, that its effect on germs is very marked, the bacteria of
* Proc. Roy. Soc, 1884. t Proc Boy. Soc. Edin., vol. xv., p. 54.
:;: ZeitF.fur Eyj., 1893, p. 427.
CHEMICAL DISINFECTANTS. 75
typhoid, cholera, and diphtheria being destroyed by 1 per cent, in one
minute, the two latter by 1 per 1000 in the same time, while typhoid
with 1 per mille required five minutes. It was very successful when
tried on the dejecta of cholera. The price of a 1 per 1000 solution is
about one-quarter that of 3 per cent, carbolic acid, which it excels in
efl&ciency. Dr. Otto Riedel * had previously in a number of experi-
ments established its value, pronouncing it not very })oisonous, and as
having about three times the power of phenol. Webb states that
chloride of iodine, mixed with talc and stearin or petroleum and burnt,
gives an active vapour. +
lodates are disinfectant, easily giving off oxygen and even iodine.
Iodine dissolves at once in an alkali, producing a mixture of iodide
and iodate, which, on the addition of an acid, liberates hydriodic and
iodic acids. These acids interact on one another, setting free iodine
as a precipitate if strong, or in solution if weak.
HIO3 + 5HI = 3I2 + 3H2O.
Sonstadt has proposed J a mixture of calcium iodate and an alkaline
salicylate for destroying the disease-bacteria of pleuro-pneumonia, &.C.,
by spray or vapour. Stronger solutions are made by adding sodium
or potassium citrate, which increases the solubility of the iodate. "It
may be used as a lotion for sores, bites, or wounds, by injections for
cholera or typhoid, or internally." Griffiths states § that a solution
containing 0*5 per cent, of potassium iodate destroys several microbes.
Periodates. — Salts of periodic acid, HIO^, have been recently much
extolled as disinfectants. Weaver asserts that "all putrefactive
microbes and the poisonous ptomaines they create are destroyed by
1 in 250,000 of ' periodate,' although singularly the aerial moulds are
not much affected by it." || One of the salts has been investigated by
Klein, who states that "it is a very powerful disinfectant, instantly
killing cholera comma bacilli, and typhus bacillus when used 1 in 5,000
of water."
Periodic acid is made by treating perchloric acid with iodine.
2HCIO4 -f I3 = 2HIO4 + CI2.
The periodates are formed by treating an iodate and an alkali with
chloribe, or treating a mixture of iodine and an alkali with excess of
chlorine :
NalOs + 2NaOH + Clj = 2NaCl + HjO + NalO^.
A great number of periodate preparations have been introduced.
" Creo " is a disinfecting powder containing tar, alkali, and periodate,
* Arb. a. d. Kais. GesundheUaamte, 1887.
t Beichardt, DesinfeclionamUlel, 1881, p. 68. t Patent No. 4,920, Oct., 18S3.
§ Proc. Boy. Soc. Editi., March, 1889. 11 Builder, Sept. 11, 1SS9.
76 DI<INFECTION AND DISINFECTANTS.
for drains, ifec. Klein states that a 1 per cent, solution kills cholera
and typhoid bacilli in five minutes. Another disinfecting powder
contains periodate with eucalyptol. lodate soaps are made.
Griffiths has given a very favourable report on ferric periodate,
1 in 250, as destroying Bacillus anlhracis and its spores.
The constitution of these various mixtures seems not to be clearly
defined, and further experience is necessary before their very wide
claims can be admitted. Their expense and possible instability have
been adduced as an objection for public and extended use. It i.s
notable that the higher oxygen compounds of iodine in the chemically
pure state are known to be very stable and do not easily give up their
oxygen. The activity of these " periodate " preparations cannot there-
fore be attributed to liberation of oxygen. They present some
analogies with the " Hermite " fluid.
ORGANIC COMPOUNDS CONTAINING THE HALOGENS.
Nearly all halogenated organic compounds have antiseptic and
anaesthetic properties. The aromatic compounds are more antiseptic
and less anjesthetic than derivatives of the hydrocarbons which have
not a closed chain. They are, therefore, to be preferred, although
chloroform and especially iodoform are still largely used.
Chloroform, CHCI3, is a strong antiseptic, and prevents putrefaction
so long as it is present. It is very volatile, boiling at 61° C, has a
high specific gravity ( 1*497), and is almost insoluble in water. These
I)roperties, its cost, and its poisonous action on animals, render it of
very limited application, almost confined, indeed, to preserving medi-
cinal infusions.
A solution of 5 per cent, chloroform in spirit is sold in small bottles
as a preservative, but is not patented. Its peculiar sweet taste and
odour are instantly recognised, even in presence of sugar.
Vallin states * that to kill already-grown bacteria requires the rela-
tively large dose of 1 per cent, of chloroform, and that it does not
fcterilise except when equal parts of chloroform and water are used.
F. Bouillat t has also obtained unsatisfactory results with the
chlorides of carbon, CCI4, C2CI4, and C2Clg.
Bromoform, CHBr.,, is similar, but more expensive, less volatile,
equally insoluble, and less stable.
Iodoform, CHIy, a yellow crystalline powder of persistent and dis-
agreeable odour, volatile, soluble in alcohol, but almost insoluble in
water, is a powerful antiseptic (proposed by Von Moorhof, of Vienna,
* TraM des Diainfectants, p. 206.
t Ze'dHch.f. prakliich. Chem., vol. xxv., p. 300.
CHEMICAL DISINFECTANTS. 77
in 1881), and is much used in hospitals for dressings, &c., in tlie form
of iodoform gauze. A liquid containing iodoform in solution or sus-
pension is readily made by adding to tincture of iodine strong liquor
potassa? or liquor sodse until the colour is destroyed, and pouring this
solution into a large bulk of water.
Iodoform night-lights have been already mentioned (p. 73).
To prevent the putrefaction of bronchial mucus in pulmonary dis-
eases, Chiaramelli recommends the internal administration of iodoform.
The medicine is eliminated by the lungs, hence its action would be
less irritant than in direct inhalation.*
The United States Pharmacopoeia gives the following formula for
iodoform gauze : —
Iodoform, 10 parts.
Ether, sp. gr. '725, 40 ,,
Alcohol, „ •820 40 ,,
Tincture of benzoin (1 in 5), . . . . 5 ,,
Glycerine, ....... 5 ,,
Gauze muslin, A sufficient quantity.
"Dissolve the iodoform in the ether, then add the alcohol, benzoin,
and glycerine ; immerse in a weighed quantity of this solution the
exact amount of muslin required to absorb it all, so as to make a
product of the required strength in iodoform (generally 30 to 50 per
cent.), dry it horizontally in a dark place. Preserve it in air-tight
receptacles."
Bisulphide of carbon has been suggested as a solvent, but its odour
and inflammability render it objectionable.
Iodoform is also used in fine powder for dusting wounds, in bougies
with cacao butter, in emulsion of 10 to 50 per cent, with glycerine,
water, and tragacanth, and in solution of 1 part iodoform with 11
of vaseline to 9 of benzene with 2 drops of oil of wintergreen for
injections.
The antiseptic power of iodoform has recently been much disputed.
While the Lancet asserts f that it is a much better antiseptic than
most other substances which are used for the same purpose, and is of
much more value than carbolic solution, and while Sir Joseph Lister
found it of the highest value for wounds, Messrs. Hehn and Rosvinj
maintain % that in a long series of experiments they have proved that
it is not antiseptic at all, but only a desiccant. " Sterilised iodoform
jelly, when inoculated with micro-organisms, was found to be full of
them, all growing freely, on the third day." Riedlin asserts § .that
" as a parasiticide it is feeble and inert, but it dries the surface of
* Lyon Midical, 1882, p. 362. + Lancet, 1887, p. 595.
J Chem. NticH, voL Iv., 1887. § Arnould's Hygiene, p. 498, 1889.
785 DISINFECTION AND DISINFECTANTS.
wounds." Miguel in hisjtable ma^ks it as very strongly antiseptic ; '^
but Bouillat f found that 10 per cent, of iodoform did not arrest putre-
faction change in extract of panci'eas. The truth is, as pointed out by
Behring, that it produces its undoubtedly beneficial effects, not by
acting directly on bacteria, but by inducing chemical changes in their
toxic products. He has ascertained that some of these toxines are
altered chemically by iodoform and rendered harmless.
Drs. Forster and Marchand % are in favour of iodoform. Dr. W.
D. Miller does not recommend it for dental purposes.
Its utility must be limited to surgery, and perhaps also to fumiga-
tion in the candles already described (p. 73).
Ethyl iodide is unstable and easily gives off iodine, of which it con-
tains 81 per cent. It has proved useful in phthisis and asthma, in
doses of 10 to 15 drops inhaled several times a day. Iodine may be
detected in the urine and saliva soon after inhalation. It possesses
germicidal powers, and readily destroys Bacillus tuberculosis.^ Ethyl
bromide has also been suggested. || Their cost and low volatility would
negative them as disinfectants.
Organic Compounds containing Iodine. — The halogens can only exert
their disinfectant action in the free state ; in combination they may
modify the properties of the compound, and make it possibly more
antiseptic, but they cannot be disinfectant in the sense of burning up
the organisms as chlorine, bromine, and iodine in the free state do.
It is true that some of these bodies are decomposed more or less slowly
by light setting free some of the halogen, but this would be a pro-
tracted, expensive, and wasteful process.
Europhen (isobutyl-cresol hydriodide) ; iodol (tetra-iodo-pyrroline) ^
aristol (di-iodo-di-thymol) ; and sozo-iodol (sodium-di-iodo-paraphenol
sulphonate) have been proposed as iodoform substitutes, and will be-
further described among the aromatic antiseptics.
The periodides of the phenols have been patented for antiseptic
use. IT
Fluorine itself is more energetic than chlorine, but on account of
the intensity of its action and the diflficulty of its preparation, is not-
likely to be made available.
Many years ago William Thomi)Son found that hydrofluoric acid,,
fluorides (acid or neutral), and silicofluorides (fluosilicates) were anti-
septic. He patented their use under the name of "Salufer." Sodium
* LcK Organixmes Vivants de VAtmonpliKre, 1883, p. 289^
t Zeitdch.f. praklisdi. Chem., vol. xxv., p. 300.
J.4rcAir. Path. Anat., vol. xciii., 1883. § Griffith's ifiero-organismSyrp. 208.
II Sormani, Atti deWInst. Lombardo, 1887.
IT Bayer of Elberfield, and Willcox, Patent No. 7,782, 1892..
CHEMICAL DISINFECTANTS. 7>
silicofluoride is a powder possessing no smell and only a slight saline
taste, and is sparingly soluble in water. A saturated solution
contains 0*61 per cent, of the salt, and is not irritating to wounds.
Thompson states that it is stronger than a 1 per 1000 solution of
mercuric chloride, and not poisonous. It is commonly sold in cubes
of a definite weight, being thus more easily carried. One cube
dissolved in a quart of water is suitable for washing the hands. It
is highly spoken of as a non-toxic antiseptic and deodorant.
A "Salufer" wool is also made.*
The recent work of Dr. Effront on the use of mineral acids for
the suppression of undesirable fermentations in breweries and dis-
tilleries, has demonstrated that hydrofluoric acid has a powerful
antiseptic action, and protects the wort from lactic and butyric
fermentations. The ammonium and potassium salts have also been
\i8ed successfully in this way. All the fluorides appear to possess
the further remarkable property of increasing the diastatic power of
malt.t
Dr. Griffiths in several experiments has found that a 0-4 per cent,
solution of sodium silicofluoride was fatal to the bacteria tried —
viz.. Micrococcus prodigiosus and Bacillus cedematis maligni. %
CHAPTER V.
THE NON-METALLIC ELEMENTS AND THEIR DERIVATIVES
[Continued).
Oxygen and Ozone : Ozonizers — Peroxide of Hydrogen — Carbon Dioxide — Nitri©
Acids and Oxides of Nitrogen : Nitrous Ether — Sulphur and its Com-
pounds : Sulphuretted Hydrogen — Sulphurous Acid — Sulphites and Bisul-
l^hites — Thiocamf — Sulphites in Food — Sulphuric Acid — Sulphates —
Bisulphide of Carbon — Boric Acid: Borax and other Borates — Boroglyceride
— Boric Acid in Food — Physiological Efifects — Influence of Gases on
Putrefaction.
OXYGEN, OZONE, AND PEROXIDE OF HYDROGEN.
Oxygen is the chief and natural disinfectant, burning up gradually all
organic substances into carbonic acid and water. This process, called
decay, affects the various bodies very differently; the more putrescent
compounds are generally the most rapidly destroyed, so that fresh air
■would be all that is needed to keep our surroundings healthy, if it
* Chem. News, vol. Ivi,, p. 132. t Monit. Sdeiit., vol. vi., 1892, p. 81.
X Proc. Roy. Soc. Edin., vol. xv., p. 37.
80 DISINFECTION AND DISINFECTANTS.
were possible to ensure that all matter likely to be a source of con-
tagion were liberally supplied with the oxygen of the air. The
oxidation of the products of those niicro-organisms which are poisonous
to man, such as the " ptomaines " and " toxines," which Selmi was the
first to investigate, is no easy task. The bacteria which produce these
toxic compounds have a higher vitality than man, and most strong
chemical agents which can kill bacteria have also a toxic effect upon
more complex organisms. No man can endure an atmosphere that
will kill these bacteria. Only the halogens, chlorine, bromine, and
iodine can penetrate their envelopes, and these cannot be given in
sufficient quantity when man is present. It is, therefore, absolutely
iiecessary to remove patients and seal rooms in order that disinfection
may be successfully accomplished.
The importance of the distinction between an antiseptic, which
simply stupefies the germs of disease for a time, and a disinfectant,
-which kills them and leaves the room sterile, cannot be too strongly
insisted upon. The use of antiseptics merely puts off the era of putre-
faction, and while arresting temporarily the evil, does not eradicate it.
The " molecular" or ordinary oxygen of the air acts slowly. When
liberated from various chemical compounds like permanganate and
peroxide of hydrogen it is said to be in a " nascent '"' or atomic con-
<iition, and is then far more active.
A number of inventions attempt to increase the power of atmo-
spheric oxygen by mechanical means. Thus it has been proposed to
compress the oxygen into water, increasing the solubility, and there-
foi'e presumably the activity.* Similarly J. Konig, with a view to
increase the rate of atmospheric oxidation of the waste water of
tanneries and slaughter-houses, produces a flow over a tinned iron net
4'5 metres high, with a breadth of 1 metre for every 12 litres per
minute, giving as the result of an experiment : —
Per Litre.
Oxygen,
Sulphuretted Hydrogen,
Sulphuric Acid, ....
Before.
3 c.c.
20*4 milligrms.
48-6
After.
9 c.c.
0'9 milligrms.
72
proving that strong oxidation had taken place, f On the same prin-
ciple polluted water flowing over weirs and waterfalls is oxidised and
becomes clear and brilliant. Pathogenic organisms may not, however,
be entirely removed by such aeration, and may set up changes again
lower down.
* E. Scruby, Patent No. 5330, 1891. t Chem. Zeilttng, vol. viii., pp. 56, 1003.
CHEMICAL DISINFECTANTS. 81
The self-purification of rivers in this way is now accepted by most
chemists, the natural aeration being aided by infusoria and vegetation
in removing most of the dead organic matter and in reducing the
number of micro-organisms present. *
Ozone, O3, is present in country air, but absent in towns, being
quickly consumed by the organic matter present in the air. It is an
allotropic modification of oxygen produced by atmospheric electrical
disturbances, but owing to its energetic oxidising, it is soon destroyed.
It closely resembles chlorine in its chemical activity. Its energy has led
several inventors to propose electrical means for disinfection, as ordinary
oxygen becomes ozonised when subjected to an electric current.
Hagenf proposes to ozonise oxygen by the usual silent discharge
method, then to pass it over the articles to be disinfected, or introduce
it into sewage, when the ozone, O3, decomposes into Og (ordinary or
'* molecular" oxygen), and the atom of "nascent" oxygen, which acts
upon the organic matter more rapidly than when in the ordinary
molecular condition. The remaining ordinary oxygen, mixed with a
little carbonic acid, derived from the oxidation of organic matters, is
carried back and ozonised again. The process can, therefore, be made
a continuous one, the carbonic acid being absorbed by lime. It must
however, be borne in mind that : —
1. No ozoniser yet invented raises the ozo7ie to more than 10 per cent.,
and generally not over 1 or 2 per cent., and this strength is hardly
sufiicient for sewage. It is well known that, owing to diflfusion laws,
a gas acts far less actively when mixed with a large quantity of
another inert gas.
2. A large volume of gas would he required. If the sewage contained
1 per cent, of organic matter, 1 gallon would contain about 50 grammes,
which would require about 10 grms. of "nascent" oxygen, or 30 grms.
of ozone. Assuming the ozonised oxygen to contain 5 per cent, of
ozone, 300 litres of ozonised oxygen would be required to disinfect
1 gallon of sewage if the ozone all acted. But as, owing to difiusion,
it is reasonable to assume that only part of the ozone would act, a very
much larger amount of gas would be required to effect the purpose.
3. It comes in competition %mth chlorine, which is more soluble, and
therefore, more rapidly absorbed, and as it can be easily produced in a
pure state (100 per cent, as against 5 per cent.), a quicker and more
certain action from its use can l)e relied on.
4. Tlie question of cost. "With equal efficiency, this would of course
decide.
* Jowm. Sot. Chem. Industry, 1891, p. 720 ; Report of State B. of Health,
Mass., U.a.A., p. 783 ; Proc. Inst, Civ. Engineers, 105, vol. Hi., p. 9.
t Brin, October, 1881, patent void.
6
82. DISINFECTIOK AND DISINFECTANTS.
J. T. Wood* converts sewage or other polluted liquid into spray by
the action of a blast of *' air, oxygen, ozone, or other suitable gas "
under pressure, by which it take^ up more than it would under
ordinary circumstances. "Auy chemical precipitant" is projected
into the spray, the sewage allowed to settle in tanks, and the clear
liquid further purified by passing it over "oxidising stairs," the
" risers " being provided with openings which communicate with tubes
containing the ozonised air under pressure. Modifications of the
air-blast are described applicable to filter-beds and the weirs of rivers.
It is to be feared that the expense would be prohibitive. It does not
seem to have been tried on the large scale.
In the dry state, ozone has very little action on micro-organisms,
but when moist is a very powerful bactericide. Ohlmuller f found
that when bubbled through water in which bacteria were suspended,
the strength being 15 milligrammes of ozone in 1 litre of air, anthrax
spores (the most difiScult of all to destroy) were killed in ten minutes
by not less than 90 milligrammes of ozone to the litre of water, anthrax
bacilli by 58 mgms., typhoid by 19*5 mgms., and cholera by about
18 mgms. A most important factor to be taken into account is that,
when the water contains organic matter the action is much diminished,
since the ozone attacks the unorganised matters first, and in so doing
is destroyed. It must not be forgotten that the oxidation of organic
matter purifies the water, and would apparently render it less liable ta
subsequent infection, as the pabulum for the bacteria is diminished.
Recent researches seem to show, however, that the pathogenic
organisms actually multiply with much greater rapidity in pure waters
than in ordinary river waters, although they subsequently decline
equally rapidly. No process, therefore, that is simply founded on
diminishing the organic matter in water, can be regarded as trust-
worthy.
It will be noticed from the above experiments that a very large
volume of air must be driven through the liquid, amounting for
anthrax spores to six times the volume of the water treated before
sterilisation can be assured. Since no materials, except glass or stone-
ware, resist the action of ozone, metals, wood, grease, indiarubber, &c.,
must be avoided in the construction of any apparatus employed.
In generating ozone, the temperature is of importance. At 6° C.
no ozone appears to be formed ; from this point the yield increases up
to 24° C, then declines.
When permanganates are treated with strong sulphuric acid, ozone
is evolved. Meyer J makes an intimate mixture of barium perman-
* Patent No. 22,747, 1891. t Arheitena. d. Kais. Gemnd.y 1892, vol, viii., p. 229.
t Patent No. 16,463, 1888.
CHEMICAL DISINFECTANTS. 83
ganate and sodium bisulphate in the proportion of 25 per cent, of the
foi-raer and 10 per cent, of the latter. " If sufficient water be added
to sucli a mixture so as to form a thick syrup, ozonised oxygen will he
evolved."
The cheapest way of obtaining ozonised air is by means of the
silent electric discharge. A convenient method, however, for gene-
rating it in small quantities is by means of moist phosphorus, keeping
it constantly cool to avoid inflammation.
A. Riche first proposed moistening the phosphorus with a solution
of potassium bichromate and sulphuric acid, instead of water, and
aspirating or, better, driving a slow current of air over it. He
mentions a form of " kerite " as the best material for the tubes.
Kattenhoy* places the sticks of phosphorus in glass-capped holders,
just projecting from a solution of potassium permanganate in 10 per
cent. suli>huric acid. The whole is enclosed under a bell-jar pierced
with holes for the outlet of ozonised air, with a locked cover to prevent
tampering. There is a funnel to add more liquid when required, and
a sliding glass-rod support to adjust the level of the phosphorus. Such
an apparatus might be of service for inlet ventilators, but its use
would not be advisable in a room, since even a trace of ozone in §xcess
would be irritating to the lungs.
At Berlin the electrical manufacture of ozone on a large scale has
been attempted for sanitary purposes.
Andreoli's apparatus, at present in operation at Allen ik Hanbury's
works at Bethnal Green, is based upon the silent discharge of electri-
city from points in the well-known " brush " or glow, as distinguished
from the spark. The former generates ozone, whereas the latter, by
its high temperature, destroys it. A large number of serrated strips of
tinned iron are arranged parallel to one another so as to form gratings
on opposite sides of plates of glass. The gratings are connected with
the poles of a dynamo-transformer, giving a high-tension current of
10,000 volts. The apparatus gives a larger surface and a more
uniform distribution of the current than other ozonisers of the
Siemens' type. Air is driven by a fan through a cotton wool tilter at
a rate of 160 cubic feet per minute, then, after cooling, and drying by
sulphuric acid on pumice, it passes over the gratings by which about
6 per cent, is calculated to be ozonised.
The same inventor has smaller open ozonisers intended for domestic
use, which can be worked by an electric supply current.f
Dr. Forster, of Berlin, proposes the supply of a small quantity of
ozone to the air of towns, stating that many epidemics, such as
influenza, arise at times when the atmospheric ozone is at its
• Patent No. 24,709, 1S93. f Industries and Iron, Aug. 18, 1893.
84 DISINFECTION AND DISINFECTANTS.
lowest, and that an artificial supply might prevent or modify the
outbreaks.
Many years ago an attempt was made to supplement the advantages
to be derived from a winter's sojourn in the High Alps by supplying
the air of the hotel at Maloja with ozone from powerful induction
coils, but it seems that no special benefit from its use was felt by the
patients. Dr. Hassall's experience at his sanatorium at San Kemo
was also disappointing. There are, however, many cases in which it
is stated to have proved V^eneficial in phthisis, and late experiments in
the Berlin hospitals have shown results in its favour.
Peroxide of Hydrogen, H.^O^, is prepared by acting on a peroxide of
an alkaline earth by an acid, e.g. : —
BaOa + CO2 + H2O = BaCOg + HoOj
BaOj + H2SO4 (dilute) = BaS04 + H2O2
It is a syrupy, inodorous, and neutral liquid, which easily decom-
poses into water and nascent oxygen, hence bleaches and acts as a
powerful oxidising agent. In the dilute state it is neither irritant
nor poisonous. Its instability is lessened by the addition of a small
quantity of acid. Two forms occur in commerce — " ten volumes" and
" twenty volumes" — indicating nominally the number of times its
volume of oxygen it gives off when treated with peroxide of manganese,
according to the following equation —
H2O2 = H2O +
The commercial peroxide should always be tested as its quality is
often very inferior.*
When an electric current is passed through water, whether the
gases oxygen and hydrogen be evolved, or whether the current be so
weak that the oxygen remains dissolved, the latter is ozonised, and
the water acquires oxidising properties, and behaves as if it contained
peroxide of hydrogen. Such a solution has been patented, but the
product is too weak to be of use. " Ozonised water " has been intro-
duced under the name of " antibacterikon."
Peroxide of hydrogen is probably present in the "Hermite"
solution already described (p. 67).
As a disinfectant hydrogen peroxide would be excellent if it were
quicker in its action. Angus Smith in 1869 called it " the disin-
fectant of the future." It oxidises such bodies as sulphuretted
hydrogen readily, it has no smell of its own, and is not poisonous.
Metals and fabrics are not attacked ; it has not, like permanganate,
the tendency to act on inert matter, though it possesses the true
characters of a disinfectant. Its action has been recently studied
* For a simple method of measuring the gas evolved, see Methods of Analysis,
Chap. XV.
CHEMICAL DISINFECTANTS. 86
in some detail by MM. Paul Bert and Reynard.* They found that
all fermentations caused by bacteria are at once stopped by peroxide
of hydrogen, and the ferment killed; while no effect is produced on
enzymes, such as diastase and those of saliva, gastric juice, and the
pancreas. When fibrin has been dissolved in dilute hydrochloric acid,
or changed into fibrin-peptone by artificial digestion, hydrogen per-
oxide is without action on it. It has no eflfect on foods, like albumen,
casein, milk, eggs, fats, sugar, starch, and juice of fruits. So that
it is practically one of the few disinfectants which have no effect on
digestion, and yet prevent the interfering action of organisms.
Van Ti'ompt asserted that 1 part of peroxide of hydrogen in
10,000 of polluted water, when shaken up and allowed to stand for
twenty -four hours, was usually sufl&cient to sterilise a water.
Altehoefer, however, found, + that to ensure sterility, it was advisable
to use larger quantities, namely 1 part in 1,000 parts of water.
" Experiments made with waters purposely infected with cholera and
typhoid bacilli, showed that both these were destroyed in twenty-
four hours by 1 per niille of hydrogen peroxide." Altehoefer,
beyond a slight taste, which disappeared after twenty-four hours,
found no detriment to the water for drinking or domestic purposes,
and recommends its application for household use as a protective
measure during any epidemics of typhoid fever or cholera. He
suggests that 10 c.c. of a 10 per cent, solution should be added to a
litre of water, or 70 grms. to the gallon. Traugott also testifies to
its innocuous character, even when swallowed in large doses. §
Guttmann injected peroxide of hydrogen hypodermically, but the
oxygen was liberated as gas in the circulation, and the animals died
of asphyxia.
Miquel places it at the head of his list of antiseptics, making
0-05 grm. sufficient to sterilise 1 litre of beef tea, as against 007 grm.
of mercuric chloride. Later observers give it much lower potency,
averaging about O'l per cent.
The class of oxides known as peroxides, which contain more oxygen
than the ordinary bases, resemble hydrogen peroxide, and are capable
of the following reactions : —
1. "When heated they give off oxygen —
H2O2 = H2O + O.
BaOj = BaO + O.
2. With hydrochloric acid they generate chlorine —
MnOj + 4HCI = MnClj + 2H,0 H- CI,.
* Berlin Ber., vol. xv., p. 1,585. t Apoth. Ze'Uung, 1890, p. 485.
tCentr.f. Bakteriol, 1890, vol. viii, p. 129. §See under Light, p. 10.
86 DISINFECTION AND DISINFECTANTS.
3. With sulphuric acid they give (ozonised) oxygen or hydrogen
peroxide —
(i.) Strong acid: BaOa + H2SO4 = BaSOi + HgO + O.
(ii.) Dilute acid : BaOo -f H2SO4 = BaSO^ + HoOa-
Many of the peroxides have consequently received attention in the
search for disinfectants.
Sodium Peroxide, Na^Og, manufactured by the Aluminium Company
at Oldbury, near Manchester, is a white powder which on exposure to
air becomes damp and spoils, therefore must be kept in tightly closed
tins. It is easily soluble in water, and acts like a solution of hydro-
gen peroxide plus caustic soda.
NaoOa + 2H2O = 2NaOH + HjOa.
If acid be added to the powder, hydrogen dioxide or ozonised oxy-
gen is produced, according as the acid is weak or strong.
Jacobsen* mixes "dioxide of barium, strontium, or calcium with
any desired metallic salt." Peroxide of barium is cheaply obtained in
Erin's oxygen process. Carbonic acid of the air, in the presence of
. water, causes it to yield peroxide of hydrogen.
Schone is of opinion that peroxide of hydrogen exists naturally in
the atmosphere and in waters. The point is not yet proved, f
Dr. Richardson proposes to saturate peroxide of hydrogen with
iodine (very little dissolves), then to add 2i per cent, of sea salt, and
to use the mixture as an antiseptic spray in an "atomiser."
Peroxide of hydrogen and ozone with other products are formed by
the slow oxidation of essential oils in presence of air and water,
especially if warmed. Such a product, consisting of turpentine oil,
water, and air, was patented:}: under the name of "Sanitas;" more
, recently § resin, resin oil, camphor, and thymol have been added.
These antiseptics would supplement the action of the peroxide of
hydrogen or ozone that might be present (see p. 215).
J. Y. Johnson || causes air or oxygen to pass through a mixture of
9 parts of water and 1 part of spirit of turpentine, maintained at the
ordinary temperature. "When sufficiently saturated with ozone, it is
used as a disinfectant for washing wounds.
A convenient test for the presence of peroxide of hydrogen is to add
a drop of potassium bichromate solution and a little dilute sulphuric
acid to the disinfectant. A blue colour is produced on shaking
with ether. " Sanitas " answers to this test when freshly prepared.
* Patent No. 1,711, 1882. t Chem. News, April 27, 1894.
t Patent No. 274, 1878. § Patent No. 1,172, 1882.
II Patent No. 14,864, 1884.
CHEMICAL DISINFECTANTS. 87
NITRIC AOm AND OXIDES OF NITROGEN.
Nitric Acid, HNO3, when pure is colourless, and has a not very-
powerful nitrous odour, as compared with the lower oxides which give
the colour and suffocating sraell to the impure acid. Its specific
gravity is 1-52, and boiling point 113° C. As one of the strongest of
oxidising agents, it is actively disinfectant, but also very corrosive and
poisonous. It oxidises organic matters to such compounds as oxalic
acid, and then finally to carbonic acid and water, being itself reduced
successively to the lower oxides of nitrogen, which in turn combine
with the organic substances to form nitro-derivatives like pyroxylin,
nitroglycerin, and picric acid. The latter class of bodies, when soluble
or volatile, are themselves poisonous and disinfectant.
Nearly all metals are attacked by nitric acid, giving nitrates and
oxides of nitrogen, for instance —
3Cu + 8HNO3 = 3Cu(N03)2 + 2N0 + 4H2O.
If sulphuric acid be added at the same time, the whole of the nitric
a,cid is driven off as nitric oxide.
Nitric acid vapours are white, and are much less injurious than the
red vapours of the oxides. Nitric oxide, NO, is colourless, but turns
red in air, forming higher oxides according to the quantity of oxygen ;
all these are exceedingly poisonous, since they form compounds with
the colouring matter of the blood. They may be described as irritant,
depressant, and narcotic.
Dr. Calvert (1872) ranks the antiseptic power of nitric acid in dilute
solution as about equal to that of hydrochloric.
Nitric acid fumigation was introduced in 1780 by Dr. J. C. Smith
for a violent outbreak of typhoid in the British Fleet. For his success
he was voted £5,000. On a large iron sand-bath over a brazier were
placed a number of stoneware capsules, each containing 12 grammes of
oil of vitriol ; when hot enough, powdered nitre was added little by
little. On stirring with a glass rod, the nitric vapours were evolved
in abundance as a thick white mist. The apparatus was carried about
among the patients, who unfortunately were affected with violent
coughing. Severe bronchial irritation followed, and some destructive
action of the surroundings. 350 grammes of nitre in 27 capsules were
used for the one hospital ship. The fumigation was daily repeated
for a week. The heat should not be too great, and the disengagement
should be gradual.
The horrible stench at once disappeared, and the epidemic was con-
quered in three weeks, the deaths falling on the first day from 31
to 9, and then steadily to the end.*
* Vallin, IMiiin/eclanlti, 1882, p 263.
88 DISINFECTION AND DISINFECTANTS.
Nitrogen Trioxide, NjOg, is a red gas of suffocating odour, combining
with water to form nitrous acid, HNOq. Girard and Pabst * describe
NoOg as a very strong disinfectant in doses so weak as to be not
dangerous, the odour being rather a^romatic and etherial. Unfortun-
ately, nitrogen trioxide is a very unstable substance, and is almost
always accompanied by the other oxides of nitrogen. The above-
named authors patented the use of "chamber-crystals," or nitro-
sulphuric acid, in a tower filled with coke. The putrid emanations
from closets or sewers are caused to pass up this tower, and, being
moist, they dilute and decompose the chamber-crystals, which evolve
this gas —
2S02(X02)OH + H2O = 2H2SO4 + N2O3.
The gases on passing out are quite innocuous, f
HaddanJ mixes an aqueous solution of sodium or other soluble
nitrite with sulphuric acid (5 parts of acid in 1,000 parts of water),
and adds the resulting dilute nitrous acid to sewage. The nitrogen
trioxide transfers oxygen to the organic matter, and is re-oxidised by
the air, so acting in the well-known way as a carrier from the atmo-
sphere to the sewage, so that " all organisms are destroyed." Although
theoretically this action enables a small quantity of oxide of nitrogen
to do an tinlimited amount of work, yet in practice the disinfection by
nitrous compounds has proved expensive, and has no advantages over
other methods.
Nitrites are somewhat antiseptic ; internally they are dangerous
(Lauder Brunton).
Nitric Peroxide, NO^, is a red irritant gas, easily condensed to a
brown liquid. If it were desirable, the latter would be the most con-
venient form for use, and could be. obtained in sealed tubes or syphons
like sulphurous acid. It is made by heating nitrate of lead.
Pb(N03)2 = PbO + 2NO2 + O.
Guyton de Morveau, in his classical work, found that this gas
was a feeble disinfectant, but irrespirable and dangerous. Payen §
places NO2 in the front rank among disinfectants. He uses for a space
of 40 cubic metres, 1,500 grammes of nitric acid, 2,000 of water, and 300
of copper turnings tied up in a thick paper bag to moderate the action.
Even thus it is liable to become too violent, and much of the nitric
acid is wasted as nitrous oxide or even nitrogen. Three-fourths of the
nitric acid remain behind as cupric nitrate, and this, of course, would
act slowly as a liquid absorbent. Payen's process was carried out in
sealed rooms during the siege of Paris. He allowed forty-eight hours
for complete disinfection. The cost is obviously very high.
♦ Disinf. de« Latrines, 1881. t Pat.mt No. 18,486, 1881.
t Patent No. 4,714, 1885. § Complex licndus, March 6, 1871.
CHEMICAL DISINFECTAXTS. 89
Notter* says that an attnospliere containing 035 per cent, of nitro-
gen peroxide killed all bacteria in putrid beef tea in forty-eight hours.
Sternberg t states that 1 per cent, of nitrogen peroxide in air will
sterilise vaccine in six hours, while J per cent, was not disinfectant.
He makes this power to be identical with those of sulphurous acid and
chlorine. There is, therefore, no apparent benefit resulting from its
\ise. Severe bronchitis and sevei'al deaths from poisoning have been
recorded as resulting from breathing this gas {Angus Smith).
Nitrous Ether (ethyl nitrite), C.^HjNOg, was tried both as an anti-
septic and disinfectant by Peyrusson and by Guillaumet in 1881. The
former considered that it disengaged ozone. + Vallin's experiments'
prove it useless. § Miquel states that in fifteen to twenty days at
20° C. it was absolutely incapable of destroying the vitality of bacteria,||
Nitrobenzene will be alluded to among organic compounds.
In conclusion, the opinion is irresistible that nitric disinfection i&
the worst of all methods, and under no circumstances should be
allowed. Fortunately the patents are few.
SULPHUR AND ITS COMPOUNDS.
The abundance of this element in volcanic districts, and the charac-
teristic odour of its compounds, sulphurous acid and sulphuretted
hydrogen, seem to account for the fact that sulphur and its compounds
have had the earliest reputation as antiseptics and disinfectants.
In Fawkes' translation of Theocritus we read —
'* Next with pure sulphur purge the house and bring
The purest water from the freshest spring,
This mixed with salt and with green olive crown'd
Will cleanse the late contaminated ground."
Sulphurous acid is still the official disinfectant ; its ease of applica-
tion and cheapness being its principal merits. The element itself, in
the form of '• flowers," is dusted on plants to kill aphides, and is
extensively used for vines against Oidium, as well as for hops and
seeds. Here it, undoubtedly, by slow oxidation, gives off sulphurous
acid. Mixed with soap it generates an alkaline sulphide, and this in
turn, by the action of the carbonic acid of the atmosphere, liberates
sulphuretted hydrogen. Given internally, as " flowers " or " milk "
of sulphur, it also creates sulphuretted hydrogen in the body, evolved
subsequently by the skin, and killing or enfeebling such parasites and
micro-organisms as cause many of the skin diseases. So " brimstone
and treacle," and the modern " sulphur lozenges," reach their reputa-
* Journ. Med. Science, Dublin, 1881, p. 508.
t Nat. Board of II., Washington, 1881. ::: Comptes Rendus, 1881, p. 492.
§ Desin/ectaiits, p. 214. li Org. de I'AtmospIt., p. 291.
^0 DISINFECTION AND DISINFECTANTS.
liion. In ointments also it is absorbed. The xitility is undoubted,
though the action is slow. To quicken it, it must be combined with
oxygen or hydrogen, so as to be soluble in water, and diffusible in
air.
Sulphuretted Hydrogen, HgS. — This gas is slightly heavier than air,
soluble in water (3 volumes dissolve in 1 of water at 15'5° C), slightly
-acid, and blackens silver and some other metals. Its odour is well
known, and it acts as a depressant poison, reducing the blood colouring
matter of animals to methsemoglobin, which is incapable of carrying
out respiration. It is, therefore, not suitable for an aerial disinfectant.
Since it destroys most bacteria, especially that of tubercle, Dr.
Bergeon* has employed it with marked success, by anal injections of
the saturated aqueous solution, for pulmonary phthisis, itc. Niepce
inhales the gas, but the former plan seems better, as not so toxic,
since Claude Bernard has established the fact that some gases, which
^re poisonous when passed into the arterial system, become innocuous
in the venous-per-intestinal absorption. Breathing continually small
■quantities of sulphuretted hydrogen is without doubt injurious to
health, producing anaemia and low vitality.
The soluble sulphides of the alkalies and alkaline earths have similar
properties, giving off the gas on exposure to air. Hence probably the
use of sulphur springs for cutaneous affections.
Dr. Percy F. Frankland found that sulphuretted hydrogen was
■detrimental to the vitality of Bacillus pyocyaneus, Koch's bacillus, and
Spirillum Finkleri, the ones specially selected as typical ; also to the
majority of microbes, a few, however, thriving on it.f It must be
remembered that sulphuretted hydrogen is itself one of the products
of putrefaction, one class of organisms, represented by Beggiatoa (the
" sewage fungus "), not only reducing the sulphates to sulphides, but
also converting the latter into solid, and often crystalline, sulphur
within their protoplasm. To such, which are not the more dangerous
ones, sulphuretted hydrogen would do no harm.
This gas is a reducing agent by means of its hydrogen, sulphur
being liberated. It is destroyed by all oxidising agents, eventually
producing sulphuric acid. The action of chlorine, bromine, and iodine
upon it has already been mentioned (p. 58). Lime and alkalies, and
salts of the heavy metals, except those of aluminium, absorb it, forming
sulphides. Ordinary acids do not remove it beyond the extent of its
solubility in water. Sulphurous acid decomposes it.
2H2S + SO2 = 2H2O + 3S.
In sewer gas ammonium sulphide, as fetid and poisonous as sul-
phuretted hydrogen itself, always exists, and seems to be one of the
* BriU Med. Joum., Dec. 18, ISSG. t Proc. Roy. Soc, vol. xlv., p. 292.
CHEMICAL DISINFECTANTS. 91
chief narcotic agents in causing suffocation in sewers. If paper moist-
ened witli lead acetate be discoloured by any emanations, sewer gas is
indicated, unless it be derived from a chemical or gas works. The
absence of sulphuretted hydrogen or of smell is, however, no proof of
efficient disinfection. Many so-called disinfectants, moreover, merely
mask one smell by creating another. Even the presence of excess, as
shown by the odour of the disinfectant, does not prove efficiency ;
there must beyond this be a sufficient percentage present, ascertainable
only by experiment and calculation.
Sulphur Dioxide or sulphurous anhydride, SO2, is a colourless gas of
specific gravity 32 (air = 14*45), with the well-known odour of burning
sulphur. One litre weighs nearly 3 grammes. It is obtained by
burning sulphur or a sulphide in air —
S -)- O2 = SOj.
One kilogramme of sulphur gives 700 litres of the gas.
It is irrespirable, producing violent coughing and suffijcation.
About 5 per cent, in air has produced fatal results, causing acute
catarrh, acid eructations, anorexia, irregularity of the bowels, and
permanently impaired digestion (Hirt, Eulenherg, »fec.), but i per cent,
can be endured for a length of time. A wet towel moistened with
washing soda enables a larger amount to be faced.
One litre of water at ordinary temperatures dissolves 50 litres, or
145 grammes, producing an acid liquid containing the unstable
H.,S03—
SOo + H2O = H2SO3.
This liquid smells strongly of the gas, as, gradually at ordinary
temperatures and rapidly on heating, it decomposes again into sulphur
dioxide and water. Hence it rapidly loses its strength unless well
stoppered. (It only slowly attacks corks, so that it can be kept in a
corked bottle.) In the anhydrous state it is not disinfectant; on
adding water it becomes active; hence the term "sulphurous acid"
will be used throughout for this agent, as more familiar and accurate.
It acts in four ways : —
1. As an acid it absorbs ammonia, compound ammonias, and organic
bases like "ptomaines" and the products of growth of pathogenic
organisms. The salts so formed (sulphites) are much less injurious.
It has this property in common with other acids.
2. It decomposes sulphides and sulphuretted hydrogen, as above
shown.
3. It reduces organic matters, or combines with them, to form com-
pounds which are in most cases inert. This explains its bleaching
action on vegetable colours, as the compounds] formed are nearly
92 DISINFECTION AND DISINFECTANTS.
colourless. But the action is evanescent, as on exposure to air it is
oxidised to sulphuric acid, and the colour often reappears.
4. As a })oison it kills living organisms.
The gas can be easily condensed to a colourless liquid by pressure,
and preserved in strong metal vessels. About 3 atmospheres (45 lbs.
on the square inch) is sufficient. Messrs. Boake «fe Co.* have intro-
duced commercially this liquefied gas, and as it is attainable in any
quantity at a cheap rate, it is much more convenient to employ than
sulphur. The vessels are opened by a lever attached to a screw. The
gas will flow steadily for forty hours, a single syphon evolving 500
litres of gas, equal to the amount obtained from about 1^ lbs. of
sulphur. They also make hermetically sealed tins which are sufficient
for the disinfection of a small room. The gas is obtained by cutting
with a knife the soft metal pipe attached to the tin.
Whenever the anhydrous gas is used, the rooms must be sprayed or
steamed to provide the necessary moisture to form the acid H2SO3.
Sponges are frequently disinfected and bleached by first immersing
them in a bath of hyposulphite of soda (| lb. to 1 gallon water), and
then adding ^ lb. of oxalic acid in crystals ; sulphurous acid is liberated
and sulphur deposited in the pores of the sponges. After washing
with boiled water, they can be kept in a weak carbolic acid solution.
The Governments of England, United States, Belgium, France,
Austria, Sweden, and some others prescribe fumigation by burning
sulphur for infected rooms. Hence, as Arnould says, it is the " official
disinfectant par excellence." Germany, amongst European nations,
however, does not recommend it officially. It is difficult to keep it
alight, and various devices have been introduced to remedy this defect.
"When sulphur is used, instead of the compressed oxide, Corfield and
Louis Parkes burn it in an iron vessel with a little spirit. Nicholls
and Billyen, and also Vallin use 8 parts of flowers of sulphur,
2 or 3 of nitre, and 2 or 3 of bran or liquorice powder. This would
give a deflagration, would retain much of the sulphur in the residue as
sulphate, and would result in rather too rapid an evolution, so that
the inevitable leakage would be greater. Another plan is to place it
on an iron tray and throw a shovelful of red-hot coals on it. When
this plan is adopted, there is usually a residue of unburnt sulphur left.
A chafing-dish of coals, properly protected, with an iron tray over it,
and lumps of sulphur distributed gives better results. Even with
these devices, it is almost impossible to keep up a combustion suffi-
ciently long, hence the liquefied gas, excluding, as it does, the risk of
fire, is much to be preferred.
J. Robertson! has devised a portable iron stove provided with an
• Patent No. 12,238, 1885. t Patent No. 10,129, 1891.
CHEMICAL DISINFECTANTS. 95
evaporating or burning pan in which is placed the chemical to be
evaporated or burnt, and connected with a fan, by means of which air
is drawn through a hose or flue to the place where they are to be
utilised.
J. H. Johnson * lias a chamber for sulphuring clothes, rags, &c.
Kingzett's sulphur candles are made in the form of a night-light,
and are placed in a water-jacket as a precaution against fire. They
are made of sulphur with a "powerful oxidising agent," and a wick.
These are arranged to burn two hours. They ai"e very convenient if
they yield sufficient of the gas. The cost is moderate.
Seabury's sulphur candles t also burn two hours, and differ from the
above in having a large compound wick. Morse and Bourne's patent];
principally affects the shape of these candles. §
Neutral sulphites, such as sodium sulphite, Ka^SOg, are not decom-
posed like hypochlorites by the carbonic acid of the air, hence they
neither smell of nor give off sulphur dioxide. Both the acid and its
salts absorb oxygen from the air, changing to sulphates, and therefore
they act as i*educing agents. The acid or bisulphites of sodium,
calcium, and magnesium are much used for preserving provisions ;
they slowly evolve sulphurous acid gas. The sulphites, as distinguished
from the free acid, are poor disinfectants, but a large number of patents
have been taken out for their use either alone or in mixtures. Most
of these patents are of doubtful utility.
A bisulphate mixed with a bisulphite would be a convenient form,
which would evolve sulphurous acid ou being moistened, thus —
NaHSOi + NaHSOs ^ Na2S04 + HjO + SOg.
R. Y. Tuson|| suggested the use of various metallic sulphites, andU
proposed to employ a saturated solution of sulphurous acid in liquid
phenol. G. Purvis ** charges sewage with sulphurous acid, then neu-
tralises with lime and adds other substances in the proportion per
gallon of 7*5 grains sulphurous acid, 7*5 grains lime, 4 grains aluminium
sulphate, and 1 to 5 grains charcoal, ft
M'Dougal and Meldrum H state that "the prejudicial and offensive
products of the .decomposition of sewage matter are mainly compounds
of sulphur and phosphorus with hydrogen or alkalies. Sulphurous
acid decomposes these, forming thiosulphates, hypophosphites, «fec.
This is the base of the process. The gas is generated by burning
sulphur, pyrites or the spent oxide of gas works, and passed in until
the liquid is acid."
* Patent No. 2,567, 1883. t Patent No. 6,407. 1893. :;: No. 18,434," 1891.
§ Journ. Soc. CJiem. Industry, Feb. 29, 1892. I! Patent No. 8,645, 1879.
IT Patent No. 1,081, 1879. ** Patent No. 18,286, 1891.
.tt See also Van Alsing, Patent No. 2,644, 1878. tt Patent No. 2,846, 1891.
94- DISINFECTION AND DISINFECTANTS.
Fryer and Alliott* place sewage pails in an air-tight vessel, exhaust
the air, then let in steam, hot air, sulphurous acid, chlorine, phenol
vapour, or other volatile disinfectant. The action is thus more con-
centrated. The process is also staled to be suitable for the disinfection
of wearing apparel, bedding, «fec. There are a number of other patents
of less importance.
Thiocamf (Prof. E. Reynolds) is a liquid formed by leading sulphur-
ous acid into a bottle containing camphor. The resulting product
contains 30 to 35 per cent, of sulphur dioxide. Various other disinfect-
ants (not oxidisers) can be mixed with it. On exposure to air it gives
off its sulphurous acid and leaves a white antiseptic residue of, pre-
sumably, camphor. A 6-ounce bottle evolves about 20 litres ot gas.
It was recommended by the Disinfecting Committee of the House of
Commons.
The official directions for sulj)hur fumigation are as follow ; — British
Local Government Board : 1| lbs. of sulphur burnt over a small fire,
in a carefully sealed room, for six hours or more. (This would give
1*76 per cent, of sulphurous acid in the air.) The wall paper is then
to be stripped off and burnt, and the ceiling and floors thoroughly
washed, &c. Recent suggestions of the Society of Medical Officers of
Health add that bedding and clothes should be spread out on lines,
that the sulphur should be burnt over a pail of water to supply
moisture, and that the time should be twenty-four hours. In Belgium
the disinfection is purely domestic, except in the case of persons. The
quantity is 20 to 30 grammes of sulphur per cubic metre, or 2 to 3 per
cent. In Paris 20 grammes is used per cubic metre for forty-eight
hours. In Berlin sulphur disinfeclion is not much employed. In
Austria and Sweden the official regulations advise the use of sulphurous
acid. The American Committee on Disinfection enjoin "exposure for
twelve hours to an atmosphere containing at least 4 per cent, of sul-
phurous acid in presence of moisture = 1^ to 2 kilos, of sulphur for
every 28 cubic metres " — an ordinarily sized room.
For ships arriving in the Mississippi from infected ports, the cargo
is sprayed with corrosive sublimate solution, but sulphur fumigation
is used for the hold. A battery of eighteen furnaces contained in a
specially constructed tug is used for heatiilg the sulphur, and the gas
mixed with air is forced into the hold at the rate of 180,000 cubic feet
per hour by means of a fan. 100 lbs. to lj700 lbs. sulphur is used for
each vessel.
There has been a great conflict of opinion on the value of sul-
phurous acid disinfection. Vallin f pronounced it perfect, Arnould J
says that " sulphuric acid, even in the almost inapplicable dose of
• Patent No. 1,565> 1877. t Traiti des Disinfectants. X Hygiene, 1889, p. 501.
CHEMICAL DISINFECTANTS. 9&
10 per cent., is an uncertain means of destroying spores ; even mois-
ture does not ensure success." Dr. Cassedebat, after a research at the
Marseilles School of Medicine,* remarks " even in the highest doses
it is too inconstant to be recognised in the disinfection of virus."
Savarellif condemns it. Miquel could not kill germs in twenty
days.:^ Sternberg's experiments § were unfavourable — "it requires
special conditions rather than abundance." Dr. A. J. Martin II says
" its efficacy is contestible, without counting its public nuisance."
Dujardin-Beaumetz,1I who studied the behaviour of this gas with
Pasteur and Roux, found that 20 grammes of sulphur, as used in the
official French fumigation, did not kill JBacillus anthracis, though it
sterilised tubes of vaccine.** Since Wolffhiigel's experimentsff in 1881,
sulphurous acid has quite lost its reputation in Germany. Kochijt
obtained similar results ; he spread the spores about in a room where
sulphur was burnt, or laid them on boards which were then washed or
sprayed with a solution of sulphurous acid and tested by transference
to culture solutions or by inoculation. §§
Dubief and Bruhl |j|l state that " sulphurous acid has the most de-
structive effect on aerial microbes, especially moist, acting mainly on
the spores of bacteria, and when pure and acting for a long period, it.
may prove fatal to dry germs."
M. d'Abaddee states that of the Sicilian labourers engaged in
sulphur works only 8 or 9 per cent, suffer from intermittent fever as-
against 90 per cent, of those not so occupied. The sulphur works in
the marshy plain of Catania protect the people in the vicinity from an
evil that causes other villages to be deserted.llli This tends to prove-
that sulphurous acid is strongly antagonistic to malaria;
Dr. P. Frankland *** found that it killed several pathogenic
organisms. Baumann destroyed B. tuberculosis with it, and has cured
several cases of early phthisis by burning sulphur.
Klein has furnished the key to these discrepancies by showing
that although " most pathogenic microbes do not thrive in an acid
medium, some putrefactive and zymogenic organisms can thrive well
in acid — e.g., Bacillus subiilis, Micrococcus urece in acid urine, Jcc." ttt
• Bevue de Hygiene, 1891. t Giom. Soc. Ital. d'llyg., 1890.
X Les Org. vivanta de VAtmc^ph., 1883, p. 289, et seq.
%^fed. News of Philadelphia, March 28, 18S5.
II Soc. de Med. Publique, 1892, 1 Bull, de VAcad. de 3fed.y Sept. 9, 1884.
*• See Rochard's Encydopicdie d' Hygiene, vol. v., 1893.
HMittheil. a. d. Kais. Gesundh., vol. i., p. 188. :::::: Ibid., p. 234.
§§ Wolflfhiigel and Proskauer, Chem. Centralblalt, vol. xiii., p. 334.
nil Comptes Rendus, 1889. HIT Journ. Soc. Chem. Ind., voL L, p. 51a»
••• Proc. Boy. Soc, vol. xlv., p. 292.
t++ Micro-organisms and Diseases, 1886, p. 258.
96 DISINFECTION AND DISINFECTANTS.
Therefore, sulphur disinfection, though generally successful, may
sometimes fail. Wynter Blyth is also of the same opinion.
M. Thoinot sums up thus in hiH^Beport to tlie Committee of Public
Hygiene o/tJie Seine, 1891 — "The disinfection by sulphurous acid is
only a practice of waiting, but it is a good practice, and ought not to
be despised." *
It was objected to the halogens that they were apt to corrode the
fabrics submitted to them. The same thing is liable to happen with
sulphurous acid, as its oxidation in air leaves behind sulphuric acid,
which is not volatile.
Sulphurous acid and the bisulphites are widely used for preserving
food. They act (1) by absorbing oxygen, (2) by suspending the growth
■of moulds and ferments, like those of the vinous, acetous, lactic, and
butyric fermentations. Tn canned goods they are objectionable, as
they dissolve tin and lead from the metallic envelope. Dr. Pfeiffer, of
Munich, asserts that large quantities of sulphurous acid and bisul-
phites in beer, itc, are undoubtedly injurious to health. The
maximum allowed for wine and beer in Austria is 8 milligrammes per
litre, on the basis of the opinion of the Medical Faculty, March 19,
1887. But at least 40 milligrammes per litre might be allow'ed
without injury.! Nessler says that 2*7 to 5*4 milligrammes per litre
is sufficient to prevent secondary clianges in wine, whilst 22 milli-
grammes suppresses fermentation for fully twenty -eight days.
Calcium bisulphite and sulphurous acid in more than a minute
trace spoil the flavour of most foods, giving a flatness and metallic
taste which is distinctly perceptible. These salts are extensively used
in beer (in finings), in wines and fruit syrups to absorb oxygen, and to
hinder secondary fermentations. They are the least noxious of pre-
parations of this kind. L. Pfeiffer, in a paper on the poisonous action
■of sulphurous acid and its salts, J states that sulphites are sometimes
added to wine in such quantities as to produce injurious results. Out
of eighty specimens of wines examined by Kammerer, sixteen contained
sulphites in quantities ranging from -017 to '093 gramme per litre.
List detected sulphites in a large number of French wines, the amount
varying from '009 to '135 gramme per litre. Their presence in wines
is likely to cause irritation, if the quantity of acid exceeds 0*08 gramme
per litre.
Johnson and Saladin § propose an apparatus for cleansing grain,
* See also Klein, Lawes and Lingard in Report of M. Off. of Local Gov. Board,
1884, on " Chlorine and sulphurous acid on Swine fever virus ; and Crookshank's
Bacteriology, 1887, p. 150.
t Lehmann's Hygiene, tr, by Crookes, 1893.
XMed. Chranide, Oct., 1890. § Patent No. 689, 1893.
NON-METALLIC ELEMENTS AND THEIB DERIVATIVES. 97
freeing it from dust, germs, &c., by blowing and washing, or sterilising
with sulphurous acid, vapour of bisulphide of carbon, or other gas or
vapour, by a tower arrangement down which the grain falls and is
distributed and mixed in its course by baffling or deflecting pins.
Thiosulphates (the " hyposulphites " of commerce) are antiseptic, but
not strongly.
Sulphuric Acid, H0SO4, stands next to hydrochloric as an antiseptic ;
it is only partially a disinfectant. Koch first announced that the
cholera bacillus was afiected by acids. Kitasato subsequently showed
that this acid and hydrochloric destroyed cholera germs in a few hours.
A. Stutzer* states that a solution of 0-05 per cent, of sulphuric acid
is fatal to cholera bacilli in fifteen minutes (see Klein's remark, ante,
p. 95). He tried 0-02 per cent., which took twenty-four hours; 0*03 per
cent, even for five hours did not kill all. He also examined whether iron
pipes could be disinfected by sulphuric acid without the metal being
corroded, with the result that it cleaned out rust and sediment without
sensibly attacking the metal. He estimates that 100 kilos, of 60° B.
sulphuric acid (1 lb. of acid to 40 gallons of water) would disinfect
40,000 litres of water at an expense for acid of about 0'9d. per 100
gallons of water treated. Dr. Ivanoff t has also demonstrated that
004 per cent, of this acid destroys cholera bacilli in Berlin sewage,
and 0'08 per cent, in that from Potsdam.
According to Miquel, 2 or 3 grammes of sulphuric acid produces an
equal effect to 7 milligrammes of mercuric chloride. Endemann +
found it very difficult to develop bacteria in fluids containing acid
I)hosphates. Whitthread's patent, 1872, for precipitating sewage by
acid phosphate of lime and then milk of lime, was tried at Luton in
1874, and very favourably reported on by Corfield. He used a solution
of 1 in 1000. The use of acid phosphates was proposed previously
by David Forbes, and several patents claim them as disinfectants. §
Endemann has also shown that many acids are powerfully disinfectant,
destroying the life of bacteria completely, even if present in small
quantities (but not of spores?). One part of hydrochloric acid in 64
parts of Cohn's fluid well stocked with bacteria, destroyed these com-
pletely.
The toxine Caclaverine, C^Hj^No {Brieger), occurs in the products of
cultivation of the cholera bacillus. Kobert |] says that it is less dan-
gerous when converted into a neutral salt. To this he attributes
partly the benefit derived in cholera from acid drinks (see p. 261,
• Zeitsch. fur Hyg., 1893, p. 116. + Ihid., 1893, p. 80.
X Chem. News, vol. xU., j). 152.
§ Corfield and Parkes, on Treatment and Ut'diaation of Setcaije, 1887, p. 30G.
II Pharm. Centralhalle, 1891, p. 162.
7
98 DISINFECTION AND DISINFECTANTS.
Chap, xiii.), and from washing the intestines with acid liquids, of which
weak sulphuric is the best, especially as it has been shown that the
cholera bacillus itself is affected by traces of acid.
Rohe* is of the opinion that whilst sulphuric acid, 1 in 800, is
antiseptic in some cases, it cannot be depended on as a general
antiseptic.
The Sulphates are not perceptibly antiseptic. Miquel concludes
that sodium and potassium sulphates, even dissolved to saturation in
beef tea, are incapable of preventing the germination of bacteria.
Sulphates of lime and magnesia actually encourage the growth of
many organisms, being reduced to sulphides. Those of iron, mercury,
and some other metals depend for their power on the base present,
and not on the acid.
Bisulphide of Carbon, CS,, is a colourless liquid, very volatile (boiling
point 48° C), and exceedingly inflammable ; the vapour has caused
dangerous explosions. It is heavier than water (sp. gr. 1*272), and
insoluble in it. It has ordinarily a most offensive odour and is ex-
tremely poisonous, its vapour forming in the blood methsemoglobin,
with destruction of the corpuscles, f In Patent No. 3,208, 1878, M.
Simon exposes meat to the vapour of this compound for preservation.
Dujardin-Beaumitz used carbon bisulphide internally for typhus and
diarrhoea, and found that " all offensive odours were removed from the
breath and the stools were disinfected." J
By burning it generates large quantities of sulphurous acid mixed
with carbon dioxide. The yield cannot well be increased by dissolving
sulphur in it, as the latter mostly remains unburnt in the dish.
Messrs. Price & Co. have devised a lamp for burning this liquid, so
as to generate these gases,§ but it must be used with caution on
account of its volatility and inflammability.
Carbon bisulphide is decidedly antiseptic, but its characteristics
prevent its use. In combination with sulphides of alkalies it yields
the sulphocarbonates, such as the potassium salt KgCSg, which crystal-
lises in yellow needles, soluble in water and unstable. With an
alcoholic solution of potash it forms an ethyl-sulphocarbonate or xan-
thate, CS(OC2H5)SH.
According to P. Zoller,|| small quantities of xanthates mixed with
the soil prevent the formation of fungi. Zoller and Gretell recommend
potassium xanthate as a remedy against Phylloxera.
* Hygiene, 1890, p. 357.
t See Westberg, Zeitsch. fur Anal. Chem., vol. xxxi. [4], p. 484.
i Complea Rendus, vol. xcix., p. 509. § Parkes, Hygiene, p. 517.
II DingLpol. J., vol. ccxxi., p. 191; vol. ccxxiL, p. 190.
IF Ber., vol. viii., pp. 802, 955.
NON-METALLIC ELEMENTS AND THEIR DERIVATIVES. 99
Dr. Ross considers that the poisonous action of carbon bisulphide
practically excludes it from use as a disinfectant.
Aqueous solutions containing 1 or 2 grammes of carbon bisulphide
per litre have also been found very satisfactory against Phylloxera. *
BORIC ACID AND BORATES.
Boric or Boracic Acid, H3BO3 (or HBOo . H^O) occurs in inodorous,
pearly crystalline scales, sparingly soluble in water (about 4 per cent.),
and more soluble in alcohol. The crude Tuscan volcanic borax has to
be refined for preservative uses. It has been proposed, in an Italian
patent, to import it in the native solution, but the cost of transport
would thereby be increased.
It is a weak acid, almost tasteless in dilute solution, and has no
corrosive action either on tissues or metals ; this and its absence of
odour, with a certain amount of preservative power, and little effect
on animals, have led to a large number of patents for the use of boric
acid and borates for preventing the putrefaction of animal and vege-
table substances. It is in no sense a disinfectant, and its antiseptic
powers are low, although for many years it has held a place as a
preservative for meat and vegetables. The original discoverer, Gahn,
sold in Europe two mixtures — (1) boric acid with 1 part alum, called
"aseptine;" and (2) boric acid with 2 parts alum, called "double
aseptine." It seems probable that he recognised in the alum a greater
activity than in the boric acid. Provisions in part preserved by boric
acid are generally within one or two months covered with a black
crust, but the presence of alum prevents this action taking place.
Lehmann found that fresh beef with 1 per cent, of boric acid and
50 per cent, salt pickle kept for several months at 80 °F. Endemann
proved f that boric acid acted as a preservative to fresh meat only,
and that previously salted meat could not be preserved by it.
Lehmann infers in these cases it is not the boric acid that acts as a
preservative but the substances produced by it, i.e., the acid phos-
phates (see under sulphuric acid, p. 97). He states that "other
mineral acids give exactly the same results without boric, especially
phosphoric and hydrochloric." %
Miquel classes it as "moderately antiseptic." It required 7'5
grammes to " neutralise " a litre of beef tea.
According to Lazarus § milk can only be preserved by boric acid
if the quantity added exceeds that which can be used without altering
* Compt'es Rendus, 1S91, pp. 1113, 1283, and 1330.
t Chem. News, April 2, 1880.
X Lehmann, Practical Hygiene, 1893, vol. ii., p. 247.
§ Zdt8, f. Hygiene, vol. viii.
100 DISINFECTION AND DISINFECTANTS.
the taste. The microbicidal action of boric acid is very feeble. He
is of the opinion that from 1 to 2 grammes i)er litre is without action
(compare Miquel) ; yet Stokes * states that 1 in 1000, or roughly
7 grains per pint, of boric acid will keep milk ''sweet" for forty
hours. The difference is a question of time.
Mattern finds 1 per 1000 retards the coagulation of milk from
twenty-four to thirty-six hours.
This acid has no action on vinous fermentation ; it retards the
formation of acetic acid from alcohol by mycoderma aceti only when
acetic acid is not already present.^ Lehmann sums up thus — "preser-
vation by boric acid cannot be considered as involving a new
principle ; it is merely a variation of, but by no means an improve-
ment on, vinegar pickling. The insipidity prevents its easy detection,
and brings customers to the belief that the meat is fresh. This
peculiarity is the only one recommending the use of boric acid."
Dr. C. T. Williams, of Brompton Hospital, proved that the acid
excercised no destructive influence on the bacilli of phthisis. In
fact they increased abundantly in boric solutions and develop spores.
A warm saturated solution of boric acid was recommended by Pasteur
as an antiseptic in cases of puerperal fever, but has been superseded
"by mercuric chloride in the lying-in hospitals of Paris. The
application of it to wounds and ulcers has decreased, J and in the
French Army Medical Service four times as much sublimate wool
is used as that impregnated with carbolic or boric acids. The latter
wool contains from 14 to 36 per cent, of boric acid, which is in great
jiart crystallised, and therefore irritating to the skin. This crystal-
lisation may be prevented by keeping the wool moist by glycerine.§
There is no doubt that boric acid does preserve food when used in
sufficient quantity. The earlier investigators employed such strengths
iis 1 in 12 {Jalan de la Croix); ^ to 4 per cent. [Neumann); whilst
Tallin, who used 2 to 4 per cent, of the acid, states that this strength
kills germs when borax only stupefies them.||
Borates. — Those occurring naturally are Tincal or native Borax,
Boracite or Magnesium borate, and Borocalcite or Calcium borate, and
others of less importance. Those which are soluble are somewhat
antiseptic ; they are decomposed by strong acids. The acid magnesium
biborate is one of the most soluble, and may therefore be a useful salt
for preservative purposes.H
Borax, or Sodium diborate, Na^B^Oy, occurs in large transparent
crystals, inodorous, having an alkaline taste and reaction, and soluble
* Analyst, 1S91, p. 123. t Herzen, Biedermann's CentralblaU, 1S80, p. 487.
X Lancet, vol. i, 1890, p. 1266. § Chemist and DruQgist, Feb. 18th, 1893.
jl Vallin, p. 149. IT Brit. Med. Joum., 1888, p. 1184.
NON-METALLIC ELEMENTS AND THEIR DERIVATIVES. 101
in 12 parts of water. M. Dumas, in Aug., 1872, introduced boric
acid and borax to the French Institute as preservatives for food.
Borax may be used to neutralise the acid developed in milk by
keeping. E. le Cyon * thinks that meat preserved by borax is not
diminished in nourishment, and is more readily assimilated. Subse-
quent investigators have, however, arrived at an opposite conclusion.
Ammonium Borate is more soluble ; a strong solution has been
injected into bodies for dissection.
Among the numerous patents are — No. 2,375, 1877, Taylor,
calcium borate; No. 3,001, 1880, Artimini, "boric tartrate" as an
antiseptic; No. 4,910, ditto, ditto, boric acid and borax; No. 1,127,
1882, J. Imray, preserving meat with boric and malic acids ; provi-
sional i)rotection ; 1882, Haddan, borax, glucose, and boric acid
evaporated till solid, for provisions; No. 5,153, 1882, Pielsticker, boric
acid melted with sodium phosphate and formate, " very soluble and
almost tasteless, for provisions ;" No. 6,134, 1882, J. Townsend, boric
acid, «fcc. ; No. 274, 1883, Wilkins, ditto (these two are mainly
mechanical); No. 1,429, 1883, Conron, boric acid, borax and potas-
sium nitrate, "half a pint of concentrated solution to a barrel of
3G gallons," for various infusions; No. 5,326, 1883, Lake, glycerine
and boric acid (not heated, compare Barflf's patent).
" Boroglyceride," No. 1,332, 1881, F. S. Barff, deserves further
mention. " Heat glycerine to near its boiling point, and add
boric acid as long as dissolved. Keep at 200° C. as long as water
comes off. Animal or vegetable matter is preserved by immersion in
a solution of the compound in water, alcohol, or other solvent." Boro-
glyceride claims to be glyceryl triborate —
C3H5(0H)3 + .3HB02 = C3H5(B02)3 + SHgO.
How far, like other esters, dilution breaks it up again into glycerine
and the acid, is not apparent. The solution has a different taste from
the materials, but the general properties are intermediate in their
character. It has hardly answered expectation. See under Glycerine
(p. 226) for the therapeutic effect of that body. Calcium and sodium
boro-glycerates, obtained by heating calcium borate or borax with
glycerine till the whole forms an oily liquid which solidifies on cooling,
are recoramendeil by Le Bon f for preserving food and for surgery.
It will be noticed that most of the above devices are intended to
increase the sparing solubility of boric acid. It is one of its charac-
teristics that, though having so feeble an affinity for bases, it seems
always ready to form more or less stable combinations with other acids
and with neutral bodies.
* Bied. Centr. Ayr. Chem., 1879, p. 869. + Comptea Rendtu, vol. xcv., p. 145.
102 DISINFECTION AND DISINFECTANTS.
Potassic Borotartrate or "Soluble Tartar," K(B0)C4H^0g, obtained
by heating together 1 part of boric acid, 2 of cream of tartar,
KHC^H^O^, and 24 of water, evaporating to dryness, and treating
■with alcohol to remove excess of acid, is a white non-crystalline
powder, insoluble in alcohol but very soluble in water. It has been
employed as a purgative, and also as an antiseptic, and is the " boric
tartrate " of Artimini's patent mentioned above.
Benzoboracic acid, with oils of thyme, Eucalyptus, Baptisia, Gaul-
theria, and Mentlm arvensis, containing 1 part of the acid in 30 of the
oils, is called " Listerine," and is used in surgery. There is also a
benzo-boric mouth-wash. Salicylic acid is soluble in less than GOO
parts of water ; stronger solutions may be made by using boric acid
in the proportion of 12 parts boric acid to 1,000 of water, when a
0*2 per cent, solution of salicylic acid can be obtained.* Strock's
" Antiseptic paper " is made with two solutions — A, alcohol 500,
boric acid 5, salicylic 7 ; B, water 1,588, sodium tliiosulphate 60.f
E-adlauer's " Antisepsin " is a mixture of zinc sulphate 85, zinc
iodide 25, thymol 2*5, with 10 parts of boric acid.
L. Hausler I has recently made boroglyceride into a jelly by dissol-
ving it in hot water with half or an equal weight of gelatine ; he dips
the provisions while the jelly is still liquid, and so gives them a pro-
tective coating. Before use the articles are washed in luke-warm
water.
Boric acid is also used for preserving butter and cream, for curing
hams, sprinkling over fish, &c. "Sodium chloro-borosum " is borax
and common salt. " Barmenite," according to C. Schwartz, contains
80 per cent, borax, 15 boric acid, 3 salt, and 2 sodium chlorate, with
traces of alumina. " Glacialin " is a fused mixture of borax and boric
acid.§ These preparations are extensively used on the Continent for
preserving meat, and the latter in this country for milk. How much
boric acid enters into meat which is sprinkled with or soaked in it is
not accurately known, but according to Roosen, who has patented the
use of boric solution under pressure, 500 grammes of meat take up
only ^ gramme of the acid. Covering meat with 1 per cent, boric
solution keeps it from putrefaction from four to seven days.
Hehner states,|| on the authority of Polenski, that in Germany boric
acid preservatives have been advertised under the following names : —
Berlinite, Chinese preservative powder, Brockman's salt, Australian
salt, Magdeburg preservative salt, and Heydrich's salt.
The physiological effects of borates in food seem to be more pro-
• Bevue de Chimie Industrielle, April 15, 1893. t JbicL, Feb. 15, 1893.
t Patent No. 9,145, 1893. § Journ. Soc. Chem. Ind., 1890, p. 993.
II Andlyat, 1890, p. 295.
NON-METALLIC ELEMENTS AND THEIB DERIVATIVES. 103
nounced than was formerly supposed. Artimini and Polli asserted
that doses of 3 or 4 grammes continued for months were well
tolerated by men.* Large doses produce vomiting and diarrhoea,
«fec.,t but dilute solutions seem to have no visible effect. Forster
and Schlenker have shown, in very careful and repeated experi-
ments, that daily doses of i to 3 grammes of boric acid added to
human diet affect the absorption of nutritious substances ingested,
irritate the intestines and cause them to cast more mucus and epi-
thelium. Borax probably acts like boric acid. J Forster concludes
that the use of boric acid in preserved food is of questionable value,
as it increases the secretion of bile and the excretion of albuminous
matters. Gruber likewise states that the decomposition of albumen
in animals is increased by borax. The use is said to be greatly ex-
tending, but preparations of borax for preserving meat are forbidden
in the German navy.
A French commission appointed to investigate the influence of boric
acid on the human system reported that it could be taken for a con-
siderable time without injurious effect. "Yet it is certainly neither a
regular constituent of the body nor naturally contained in food (beyond
exceedingly minute traces), and it is therefore probable that in time
constitutional difficulties would supervene."§ Leffinan and Beam||
and H. A. "Weber H have shown that food preservatives interfere with
pancreatic and salivary digestion, borax even keeping its retarding
effect up to a dilution of 1 in 2,000. Both boric acid and borax delay,
or even prevent, germination of seeds.**
If, as stated by Stokes, it requires 1 in 1,000 of boric acid to keep
milk. sweet for forty hours, 2 grains per diem are consumed per adult,
and 15 to 30 grains daily by a bottle-fed baby. This amount may
fairly be regarded as a medicinal quantity, and it is to be hoped that
legislation will prevent its use in the future.
Tests for Borates. — To a large quantity of the milk, or of the aqueous
extract of the food, add milk of lime in excess. Evaporate to dryness,
burn to ash, and dissolve in a little strong hydrochloric acid. Filter,
nearly neutralise the acid with lime, dip into it a piece of freshly
made turmeric paper. Dry this on a water bath; if boric acid be
present, the portion which has been dipped will show a rose colour,
turned dull blue by dilute soda. If there be much boric acid, the
* Annali di Chem. Med., 1877.
+ Neumann, Archiv.f. exp. Physiol., 1881, p. 148.
X Ber. deutsch. Chem. Ges., voL xvi., p. 1754.
§ Acad, des Sciences, Jan. 6, 1879. I| Joum. Soc. Chem. Itid., 1888, p. 582.
■H Joum. Amer. Chem. Soc, 1892, p. 4.
♦* Comple* liendus, 1892, voL «civ., p. 131.
104 DISINFECTION AND DISINFECTANTS.
remainder of the ash solution, if moistened with spirit, ignited, and
stirred, will show a green mantle to the flame against the red of the
calcium chloride and yellow of the soda. The green lines of boric acid
should be looked for in the spectroscope.* The quantity may be
determined by repeated distillation with methyl alcohol into a crucible
containing a known weight of ignited lime, t
Kayser J says that traces of boric acid are very widely distributed
in nature. Carrots, beet sugar, Californian wines, &c., contain it, and
it is often introduced into the glaze of enamelled vessels. But these
would only be minute traces, whereas as a preservative it would be
present in comparatively large quantities.
INFLUENCE OF GASES ON PUTREFACTION.
Bacteria have been divided into two classes — I., the aerobic, which
live and work in presence of oxygen, and die when it is exhausted ;
their gaseous products are chiefly carbonic acid and ammonia : their
type is Bacterium termo, the principal agent of putrefaction ; they
can be dealt with by exclusion of air, as in preserving in tins, especially
if sterilised first, or by reducing agents such as sulphites ; — II. the
anaerobic, which exist in absence of oxygen, and are killed hy its
presence. Many of the pathogenic organisms belong to this latter
class. Among the products are marsh gas, sulphuretted hydrogen,
phosphoretted hydrogen, carbon monoxide, nitrogen and ptomaines.
Oxidising agents like chlorine, hydrogen peroxide, and permanganate,
are their most effective destroyers. These bacteria take up the pro-
cess where the aerobic have ceased, hence the necessity of sterilising
before excluding the air.
On the principle that all living beings are first restrained, and
finally killed by their own excreta, any of the above gases should be
to a certain extent poisonous to the micro-organisms which produce
them. But they will be far more fatal to higher animals, the effects
being not only on the blood and the lungs, but also on the central
nervous system ; the more highly developed the organism, the greater
is the sensibility . §
Carbon dioxide, or "carbonic acid" COg, seems to have a special
antiseptic and even disinfectant action, inasmuch as aerated waters
and beverages have been found to be in many cases sterilised.
Slater il has found that this gas in mineral waters has a remarkable
effect in killing pathogenic bacteria (typhoid, cholera. Staphylococcus
* Kretzchmar, Chem. Zeit., vol. xi., p. 476.
t Cassal, Analyst, 1890, p. 230. t Chem. Zeitung, 1890.
§ Pettenkofer and Lehmann, MiincJien Acad. d. Wlasensch., 1887, p. 179.
II Journ. of Pathol, and Bacteriology, 1893, vol. 1., p. 468.
NON-METALLIC ELEMENTS AND THEIR DERIVATIVES. 105
j)yogenes aureus, Finkler-Prior bacillus). Ilochstetter * found the
same in the case of typhoid, cholera, rabbit septicaemia. Micrococcus
tetragemis, Finkler-Prior bacillus, Aspergillus Jlavescens, and anthrax
bacilli but not anthrax spores.
It is well known that fermented liquors preserved in bottles remain
stable for long periods, and this stability seems difficult to explain
by the self-exhaustion or deposition of any bacteria present. Bethell
in 1848 patented a process for preserving milk, which consisted ini
first boiling the milk to expel all the air contained in it, and then
saturating the liquid with carbon dioxide. The milk when so treated
remains fresh for a long time after being opened. Liquefied carbonic
acid has also been used for preserving food. Thus, butter when
placed in an iron vessel provided with a tap, and subjected to carbonic
acid under a pressure of 6 atmospheres until all the air has been
driven out, remains fresh for four or five weeks, and is not spoiled
in flavour or consistency. Carbonic acid may also be injected into
whey, giving " a refreshing drink like champagne. The carbonated
whey can be enclosed in syphons and will keep for 6 weeks."! This
method is quite innocuous, and should be substituted for the use of
salicylic or boric acid or glycerine.
Cyanogen and hydrocyanic acid vapour do not seem to be so poison-
ous to lower organisms as they are to the higher animals.
Miquel gives 0-4 of hydrocyanic acid per 1000 as sterilising beef-tea.
Ammonia, sulphuretted hydrogen, sulphurous acid, chlorine, oxygen^
ozone, and oxides of nitrogen are described under their respective
headings.
* Arbeilen a. d. kais. Gesundheitsamte, 1887, vol. ii, p. 1.
t C/iem. Traile Journ., July 15, 1893.
106 DISINFECTION AND DISINFECTANTS.
CHAPTER VI.
METALLIC SALTS.
Salts of the alkalies and alkaline earths : Caustic alkalies — Quicklime —
Sulphate of lime (Gypsum) — Slaked lime ; its use as a precipitant — Sodium
carbonate — Acid salts — Ammonia and ammonium carbonate. Zinc : Oxide
— Chloride of Zinc— Burnett's fluid — Zinc sulphate, sulphite, and other salts
— ^Various patents. Copper : Poisonous action — Cuprous chloride — Cupric
chloride, nitrate, sulphate, and acetate. Iron : The use of metallic iron for
purifying waters — Ferrous sulphate of copperas ; the objections to it — Patents
and processes — Ferric sulphate and its applications — Ferric chloride — The
value of iron salts as disinfectants. Manganese : The metal — Manganese
peroxide — Manganous salts — Manganates— Condy's fluids — Potassium per-
manganate — Other permanganates — Mechanical devices — Cost.
SALTS OF THE ALKALIES AND ALKALINE EABTHS.
The hydroxides of potassium and sodium exercise an inhibitory
influence on bacterial growth if they are present in quantities of not
less than 2 to 5 per cent. ; so do the carbonates in the proportion of
5 to 10 per cent. ; the bicarbonates have hardly any action. Miquel
classes caustic soda as "moderately antiseptic," stating that it
requires 18 grammes per litre to preserve beef tea. He asserts,
also, that many other potassium and sodium salts, and especially the
sulphates and nitrates when dissolved to saturation in beef tea, are
incapable, even in the proportion of 500 per mille, of preventing the
germination of bacteria.
In laboratories it is noticed that the development of green Proto-
coccus occurs most rapidly in solutions of potassium, calcium, and
magnesium sulphates, and sodium phosphate. Calcium chloride solu-
tions also rapidly show growths if exposed to air. Strontium salts
do not seem to display any difference. The alkaline acetates, and
tartrates quickly become mouldy, even in very strong solutions. It
will be remembered that all varieties of protoplasm contain salts of the
Alkalies and alkaline earths ; these, therefore, are actually favourable
to the life of organisms, and thus are always added to Pasteur's and
other artificial culture solutions.
Sodium chloride and the alkaline sulphates have already been
discussed (pp. 70, 98). Forster * states that salt (NaCl) destroys the
cholera bacillus, but not others. In curing hams the saltpetre is
* R. Acad, of Science, Amsterdam, April, 18S0.
METALLIC SALTS. 107
added to affect the colour and taste; it has no proved antiseptic
action. Since nitrates are produced by the nitrifying organisms by a
process of oxidation, and reduced to ammonia by the growth of other
bacteria, and as these latter are very numerous the nitrates may
properly be regarded as salts favourable to the development of many
organisms.
The weak antiseptic action of potash and soda may account for
the similar slight activity of soap, as the fatty acids do not seem to
have any very pronounced antiseptic action.
Sulphate of Lime, on account of its power of absorbing ammonia, is
a deodorant, but cannot be regarded as an antiseptic. When used in
agriculture it prevents the ammonia from escaping, but does not hinder
the decay. It has been a frequent ingredient in mixtures for pre-
cipitating sewage ; it only acts mechanically, and has the great dis-
advantage that it adds to the permanent hardness of the effluent water
(Corjield and Parkes).
Carbonate of Lime, and in fact all other insoluble metallic salts, are
inert.
Quicklime, CaO, acts only as an absorbent; it destroys organic
matter by its dehydrating action, and to this cause may be attributed
its use for accelerating the decomposition of corpses dead of infectious
diseases. There are very few microbes that can remain active auy
length of time in a dry state, but the bacilli of tubercle have been
known to exist in dry dust for more than a year.* The spores of all
known species resist drying for indefinite periods.! It is not safe,
therefore, to trust entirely to the old method of burying in lime, as,
on disinterring, the live spores may again be diffused, unless a very
long period has elapsed.
Slaked Lime or calcium hydrate, Ca(0H)2, absorbs acid vapours
and sulphuretted hydrogen, and therefore acts to a certain extent
as a deodorant. Vallin says J that limewash applied to walls is
in a certain degree antiseptic, as it forms insoluble compounds with
the organic matter present in condensed pulmonary exhalations.
For instance, it coagulates albumen and casein. This would deprive
bacteria of food, as shown by the experiments of Pettenkofer,
made for the German Cholera Commission of 1879. He concludes
that ''slaked lime destroys rapidly and completely the organisms
of putrefaction ; the proportion of | per cent, is sufficient for slightly
altered bilge-water, but when the putrefaction is strong, 1 per
cent, is required. The action on wood and metal is very slight,
* See on the "Vitality of Bacilli : Dr. Buchner, Ohio Sanitary Record, April, 1894.
+ Klein, in Stevenson's Hygiene, 1893, p. 61.
J Traite des Disinfectants, 1S82, p. 70.
108 DISINFECTION AND DISINFECTANTS.
but the lirae removes the odour of the fatty acids of putrefaction, which
is often more offensive than that of suli)hinetted hydrogen." He
mentions as a difficulty the blocking up of pipes and pumps when it is
used. The precipitation of sewage by milk of lime was the tirst
process tried by the Rivers Pollution Commission of 18G8, and was
pronounced to be a failure.* In the act of settling, the suspended
lirae carries down the greater portion of the organisms with other
impurities, and renders the water clear. It has been stated also that
the lime coats the bacteria and their spores with an insoluble envelope
of carbonate of lime. This is the fundamental idea of the use, general
in Leipzic, of the "Suvern mixture" for sewage (see chapter on
"Regulations," p. 292). This theory does not seem to have been
verified by microscopic examination. But many investigators have
proved that, although the changes are much delayed, the water is not
sterilised. The liquid is rendered alkaline, ammonia is developed,
and, in the case of sewiige, the effluent soon again becomes foul.
The State Board of Health of Massachusetts! found that it required
about 2,000 lbs. of lime to 1,000,000 gallons of sewage to reduce the
bacteria to an average of ^^^j of what they were before. In the same
experiments it was found necessary to add alum or aluminium sulphate
in addition, to prevent the subsequent distribution of the precipitated
microbes in the upper layers.
Numberless experiments on sewage have proved that, although a
partial deodorant and a claritier, lime alone is not an antiseptic, and
still less a disinfectant.
The use of lime water for preserving eggs depends on the deposition
of carbonate of lime in the pores of the shell, rendering it impervious,
and also to the lirae coagulating tlie albuminous envelope of the egg.
Sodium Carbonate, "Washing soda." — A strong solution is antag-
onistic to bacteria, but, as used for clothes, &.C., is not effectual without
boiling. Reinsch I says that 0*1 percent, of sodium carbonate (Na.,C03)
caused the multiplication of bacteria, whereas 1 per cent, diminished
the number, and 3 per cent, killed them in a sample of the Elbe water
from between Hamburg and Altona.
Surgical instruments, after being well washed with soap and water,
are frequently sterilised by boiling in a solution of bicarbonate of soda,
^ oz. to the pint.
The acid salts of alkalies act by virtue of their acidity, as men-
tioned under Sulphuric Acid (p. 97). Acid phosphates probably
have the most power in this way, but none of them have much
value.
* First Report R. P. Comm., p. 52. -[Reports, 1888-90, vol. xi., p. 737.
t CerUr. /. Bakt., 189), vol. x., p. 415.
METALLIC SALTS. 109
Kingzett lias made some experiments on the effects of chlorides,
nitrates, and sulphates on the growth of mould on flour-paste, and on
the putrefaction of extract of beef. His results generally corroborate
the statements made above.*
Ammonia is a product of the growth of many bacteria, and can there-
foie only be a restraint on them when it is present in sufficient quan-
tity to kill them by re- imbibition. Miquel classes it as " strongly
antiseptic," saying that it requires 1 "4 grammes per litre to preserve
beef tea.
Ammonium Carbonate, or smelling salts, has a similar action. The
same authority mentions ammonium chloride and sulphate as " very
feebly antiseptic," the former requiring 115 grammes per litre, and the
latter 250 grammes (or a quarter of the weight) to keep beef tea from
putrefying.!
ZINC.
Oxide of Zinc, ZnO, is a white basic powder, and, "being slightly anti-
septic and emollient, has found favour in ointments.
Chloride of Zinc, ZnCl.,, is an exceedingly deliquescent and caustic
salt ; 10 parts dissolve in 4 of water, 1 in 1 of rectified spirit, 1 in
4 (nearly) of glycerine. Its solution is acid, tastes strongly metallic
and astringent, and is very poisonous. Miquel placed it in his class 3
as "strongly disinfectant," stating that 1"9 parts in 1,000, sterilised
beef tea. It is one of the most powerful of antiseptics, ranking next
to copper sulphate and mercuric chloride. Grace Calvert found that
a solution of albumen, to which 1 per mille of zinc chloride was added,
required over forty days before germs developed. Koch says + that
zinc chloride does not act as a germicide, and that even a 5 per cent,
solution was utterly useless. This was based on anthrax spores, which
are apparently the most difficult of all to kill. Dr. Hamilton believes
that although it may not kill the germs it may make the surface a
barren spot as far as germs are concerned — i.e., act as an antiseptic.
Dr. Richardson made experiments with regard to this salt, confirming,
on the whole, the views of Dr. Hamilton. In 1875 and 1S76 Petten-
kofer and Mehlhausen directed a number of trials in the German
Fleet on the disinfectant value of zinc chloride. Bilge-water of a
specific gravity of 1017 to 1035, with a slightly alkaline reaction, at a
temperature of 20° to 30° C, was treated with a solution of 50 to
60 per cent, strength in the proportion of 1 part to 100 of bilge.
A greyish flocculent precipitate rapidly settled, leaving a nearly clear
• Brit. Med. Joum., vol. i., 1888, p. 150.
t Miquel, Les Org. de I'Atmosphire, 1883, p. 289.
tMUtheil. a. d. k. Gesund., 1881, p. 234.
110 DISINFECTION AND DISINFECTANTS.
yellowish liquid. All odour ceased, the organisms seemed to be killed,
and the reaction became remarkably acid. At the end of four
weeks the mixture showed no signs of change. One part of the solu-
tion to 1,000 of bilge caused a decrease of the odour; 2 in 1,000 com-
pletely removed sulphuretted hydrogen, much reduced the rancid
smell, and preserved the liquid for fourteen days.
A 5 per cent, solution was found to possess no corrosive action on
iron, brass, wood, or caoutchouc. It neither bleaches nor rots ordinary
fabrics, but causes a reddening and slight smarting sensation on the
skin. The deposit does not clog the pipes or valves of the pumps as
that formed when lime is used. The German Cholera Commission of
1879 prescribed zinc chloride for the disinfection of bilge-water.
In surgery an 8 per cent, solution of zinc chloride has been employed
by Sir J. Lister for antiseptic dressings. A solution of 1 to 5 per cent-
is sufficiently strong for most purposes.*
Sternberg f finds that a 2^ per cent, solution destroys bacteria, but
a 1 per cent, solution does not prevent inoculation being followed by
death. F. Boillat J points out that although a 5 per cent, solution
does not kill the spores of splenic fever, it is nevertheless a good anti-
septic. He has also shown that it and zinc sulphate both combine
with albumen to form albuminates, and that, provided sufficient of the
salt be added to unite with the whole of the albumen, no growth can
take place. In Koch's experiments he believes that the quantity of
zinc salt added only precipitated part of the albumen, leaving therefore
sufficient pabulum for the spores on the threads to develop.
Under the name of £ur7iett's Disinfecting Fluid this salt has had an
extensive use in this country. This fluid is made by allowing the
solid salt to deliquesce to a syrup, then adding water, if necessary, till
the strength is 46 to 50 per cent, of zinc chloride.
Parkes § strongly recommends it for excreta, especially for military
use. The French Pharmacopoeia prescribes a solution of 1 in 6 with
1 per cent, of hydrochloric acid to dissolve the basic chloride which, if
present, would render the solution not only turbid but somewhat
weaker.
Burnett's fluid and the Dublin Pharmacopoeia solution have a
specific gravity of 2*00, but commercially, as being formed by mere
deliquescence, are of varying strength, generally about 82 per cent.
The " Liquor Zinc Chloride" has a specific gravity of 1'46 (1*53, Squire's-
Companion, 1890), contains 25 per cent, of zinc, or about 52 jier cent.
of the chloride. De Ohaumont found in a sample of Burnett's fliiid
*Vallin, Disinfectants, p. 128.
iBvil N. Board of Health, U.S.A., 1881, vol. iii., p. 21.
XJoum.f. praktisch Chem., vol. xxv., p. 300. % Hygiene, 1878, p. 400.
METALLIC SALTS. Ill
69 per cent. Woodman and Tidy * give 47 to 53 per cent, as the
strength. This variability is a great fault of the solution ; it would
be better to state the percentage of zinc, as in the British Pharma-
copceia (25 per cent. Zn). Burnett's original formula is unknown
(de Chaumont).
The medicinal preparations are : — Lotion, 1 grain of the liquor in
1 oz. of water, or about 1 in 1,000 of zinc chloride (London Ophthal-
mic Hospital) ; jmste, liq. zinc chlor. and flour, equal parts ; glycerine,
enough to make a thick paste ; an excellent antiseptic for wounds
(London Hospital) ; opium is often added. Compound powder, zinc
oxide mixed with an equal weight of zinc chloride keeps the latter
dry enough to blow into cavities. Points or darts of zinc chloride
fused in moulds and kept in glass tubes have been used in the treat-
ment of anthrax.t Compound ditto, equal weights of the oxide and
chloride mixed with 2 parts of flour and water to make a stiff paste,
are milder and less irritating.
The official strength for rooms is 1 of the fluid to 100 of water
(about 1 of zinc chloride in 200) ; for sewers and closets half this
strength may be used.| For excreta a 10 per cent, solution should
be stirred in, using 1 part to about 9 of the excreta, making about
1 per cent, of zinc chloride present.
" Eau de Saint-Luc," which is much sold in France, is a con-
centrated impure solution of chloride and sulphate of zinc, with
occasionally some acetic acid. Specific gravity, 1-613; strength, 77
per cent, of zinc chloride. It must not be used without dilution. §
Prof. Lamelongue || injects small quantities of zinc chloride in tuber-
culosis to promote induration of the tissue, so as to " encapsule " the
bacteria.
Dr. Vidal, as an injection for fetid discharges, employed a solution
containing 15 grammes zinc chloride, 1 gramme boric acid, ammonia
to just neutralise, and 1 litre of water. H
Daudenant patented a process for sewage,* * using lime, then salts of
aluminium and zinc chloride.
This salt is also used for injecting corpses, using 8 litres of a solution
of 40° Baurae.
Zinc Nitrate, Zn(N'03)o, as a caustic eats deeper with less pain.
As a disinfectant it is inferior to the chloride, and more expensive.
Zinc Sulphate, ZnSO^, 7H2O, occurs in transparent crystals, of acid
reaction and styptic taste ; it is emetic and less antiseptic than the
chloride.
* Forensic Medicine. i B. M. J., 1887, vol. ii. p. 644.
::: B. Med. B. of Heallh. § Vallin, p. 126.
II Lancef, July 11, 1891. IT /6id., p. 346.
• • Patent No. 4203, 1886.
112 DISINFECTION AND DISINFECTANTS.
Calvert states that 1 in 200 will keep beef juice for 30 day.s "free
from animalcules and fungi." Recent investigations by Koch, Klein,
and others prove that it is of no value as a germicide. Still it has
been a favourite substance to mix with sulphates of copper and mer-
cury, probably from an idea of cheapness, although it is likely that it
may add to their action. Patent No. 19,766, 1881, treats sewage with
zinc sulphate.
Bierbach states that an article sold as "urinal cakes" consisted of
a mixture of the sulphates of zinc, copper, iron, and soda, also some
alum with resin, the salts probably being fused with the resin so as to
make them dissolve more slowly. Holmes and Em mens* propose to
utilise the spent liquor of batteries, containing zinc sulphate and
sulphuric acid, as a disinfectant.
An acid solution of sulphate of zinc coloured with indigo has recently
been used in Paris by M. Meillere for deodorising typhoid stools in
the sick room.
The disinfectant employed on the Pennsylvania Railway consists of
a solution of the chlorides of zinc, mercury, and coi)per, with a little
turpentine to act as a tell-tale. W. T. Sedgwick has tested this mix-
ture upon various typical bacteria, and concludes that its efficiency is
due to the mercuric chloride. f
"Tuson's Disinfectant" is sulphite of lime with sulphates of alum-
inium and zinc. Every pound of this mixture is said to give off
7 gallons of sulphurous acid gas.} In his patent R. V. Tuson
saturates a solution of zinc chloride (3 lbs. to the gallon) with sul-
phurous acid gas. Mercuric chloride may also be added. §
"Radlauer's Antisepsin " contains 85 parts of zinc sulphate, 25 of zinc
iodide (a good but caustic antiseptic), 2*5 of thymol, and 10 of boric
acid. It is said to be very successful for wounds and ulcers.
" Eau Larnaudes" is composed of ordinai-y water containing 23 per
■cent, zinc sulphate and 20 per cent, copper sulphate.||
Raymond of Paris has patented " an improved antiseptic, disinfect-
ing, and deodorising fluid " of the following complicated composition: —
Parts by weight : water, 1000 ; zinc sulphate, 300-500 (i.e., a saturated
solution) ; zinc acetate, 10-3 ; sodium hyposulphite, 30-5 ; aluminium
sulphate, 30-45; boric acid, 4-7; mercuric iodide, 0*10 to 0*25 (only
when required very powerful).^! The hyposulphite would be decom-
posed by the acid, and in its turn would precipitate the mercury as
sulphide.
♦ Patent No. 4,061, 1883. t Tech. Quart., 1893-6, vol. ii., p. 43.
X Lancet, 1891, vol. ii., p. 19. § Patent No. 12,222, 1887.
II Notice 8ur le nettoiement de la voie publique, Ville de Paris, 1876.
1 Patent No. 11,275, 1892.
METALLIC SALTS. 113
Zinc Acetate is used as an antiseptic in ophthalmia and gonorrhoea.
Zinc Sulphite is insoluble. Tichborne and Henston* make an anti-
septic gauze by boiling the latter with zinc sulphate, then dipping in
hot sodium sulphite solution, and washing. Zinc sulphite, ZnSOg, is
precipitated in the tissue.
Acid Sulphite of Zinc is a soluble salt, and its use as an antiseptic
has been patented by Boake and Roberts, t
Zinc Sulphocarbolate is strongly antiseptic, has no odour, and docs
not cause irritation. To spray the throat in diphtheria, kc, 5 grammes
pejr ounce is used ; for the eyes, 4 grammes per ounce ; and for injec-
tions, 60 grammes to the pint. These strengths seem very insufficient,
but perhaps there is some danger of poisoning.
Rotterine X contains 45 grains each of zinc chloride and sulphocarbo-
late, 27 of boric acid, 2^ of sodium chloride, 6 of salicylic acid, and
1 grain each of citric acid and thymol, all dissolved in a pint of water.
It is said to be more effective than 1 per mille of mercuric chloride.
Zinc Salicylate is antiseptic and sparingly soluble. Bovet § proposes
to antisepticise all houses in the course of building, by incorporating
5 per cent, of zinc salicylate in the plastei-, soaking the woodwork with
4 per cent., and the papers and hangings with 1 per cent. He says
that the additional expense does not amount to more than 2 per cent,
of the total cost of construction.
All soluble zinc salts absorb ammonia and sulphuretted hydrogen.
COPPER.
The soluble salts of copper have a distinctly poisonous action on
bacteria. They coagulate albumen, and combine with most of the
organic acids present, to form non-putrescible salts. They absorb sul-
phuretted hydrogen, ammonia, and compound ammonias, and therefore
combine with "ptomaines." In fact, copper salts rank next to
mercury in power as antiseptics. They are used (Kyan's method) for
injecting timber to kill the spores of the fungi (mainly Merutiua
lachrymans) causing dry rot. It is difficult by law to keep them out
of pickles and preserved vegetables, as they improve the colour and
add to the keeping qualities. In several cases of prosecution under
the Food and Drugs Act, for copper in food, it has been adduced by
authorities that a small quantity of copper is not injurious.]! Copper
salts are not volatile, their action is, therefore, strictly local. As anti-
septics they give way to zinc salts, since any surface washed with
* Patent No. 11,985, 1890. + Patent No. 8,509, 1886.
t Dr. Kotter, Chtm. and Drug., 1889, p. 35.
§ Bull. Soc. Ind. MtUhouse, 1890, p. 546.
Jl Soc. Chem. Ind., 1895, pp. 539 and 705.
8
Hi DISINFECTION AND DISINFECTANTS.
copper salts (or mercury) is blackened by sulphuretted hydrogen,
whereas zinc sulphide is white. Nevertheless, M. Bureg recom-
mended that curtains, clothing, wood, <kc., should be impregnated
with copper salts.
Cuprous Chloride, OugClg, is white, almost insoluble in water, bufc
somewliat soluble in dilute hydrochloric acid. On exposure to air it
becomes oxidised to cupric chloride, and therefore acts as a reducing
agent.
Kroncke * points out that for sewage treatment, compounds having
a great affinity for sulphur should yield the best results. He has
experimented with cuprous chloride as being a salt which fulfils this
condition. It is readily prepared, very easily removed from solutions,
and becomes much less poisonous when oxidised. It has the further
advantage of not being acted on by carbonate of lime. (2) The follow-
ing method was found suitable for the purification of water : — Cuprous
chloride amounting to o-xj^^j^y of the water to be treated, and ferrous
sulphate (as far as possible free from ferric), to the extent of -g-^^Q^,
are added to the water. After six hours, 177^7^577 P^''^ ^^ ^^^® ^^
added, and agitated for one hour. After settling for one and a-half
hours, the water is filtered through sand. The water, which originally
contained 40,000 to 50,000 germs per cubic centimetre, was then
found to be completely sterilised, clear, almost colourless, and free
from iron and copper. The sand filter can be used a long time
without cleansing. The cost of purifying is estimated at Is. per
1,000 cubic metres. The sediment may be burnt and the copper
recovered.
Cupric Chloride, CuClg, occurs as green very soluble crystals.
Dr. Green f has examined various copper salts as to their relative
value as disinfectants. He tried 1, 2i, o, and 10 per cent, solutions.
The test objects were — twenty-four hour old bouillon cultures of
cholera, enteric fever, Staphylococcus pyogenes aureus, anthrax free from
spores, and spores of same dried on silk threads, besides several mix-
tures of excreta and urine infected with cholera, &c. The 5 per cent,
solutions were in most cases fatal after two hours, but with anthrax
only the specimens on the threads were killed, and then only when in
contact with a 5 per cent, solution of copper chloride for twenty-seven
days, and with the 10 per cent, solution for eighteen days. The other
solutions only retarded the growth. The general result is that cupric
chloride is the most active, and that their relative activity is in accord-
ance with the proportion of copper in the compounds — viz., chloride
1 in 2*7, acetate 1 in 3-1, nitrate 1 in 3*8, sulphate 1 in 3*9. He
* Joum. fur Gasbeleucht, vol. xxxvi., p. 513.
f Proc. Ins(. Civil Eng., vol. cxiii., p. 42. Zeif, fiir Hyg., 1893, p. 495.
METALLIC SALTS. 115
states that 5 per cent, solutions of copper salts cost approximately the
same as 5 per cent, carbolic acid. It is also pointed out that although
cupric sulphate is somewhat extensively used as a disinfectant, the
chloride should take its place as being the better salt to use.
If the above results with anthrax be confirmed, there seems to be
considerable risk attending the use of copper salts altogether, as it is
impossible to be certain that anthrax or other spores are absent in
general disinfection.
Leveson and Slater* proposed for purifying sewage the addition of
crude aluminium chloride (made by treating shale with hydrochloric
acid), then chloride of copper, carbon, clay, and, finally, lime to
neutralise the acid and precipitate the metals. This patent is typical
of a large number of complicated processes that have been introduced
for the utilisation of this salt for sewage treatment.
Cupric Sulphate, CuSO^, SHgO, the cheapest copper salt, is sol-
uble in 4 parts of water. To kill bacteria of putrefaction, according
to Miquel,t a solution of 1 in 111 is required ; according to Bucholtz|
1 in 133. Calvert and M'Dougall found that a strength of 1 in 900
prevented the growth of organisms iu beef tea for eighty-six days. It
may be taken, then, that 1 per cent, is disinfectant, while 1 in 1,000
is antiseptic for most bacteria. Kingzett also noticed that a solution,
of 0'25 per cent, of cupric or mercuric sulphate prevented putrefaction
in bi-oth for sixteen days ; the observation did not last longer. §
The French authorities (1892) decided to adopt as their official
disinfectant, in combating the cholera, sulphate of copper in a 5 per
cent, solution, and, specially for the disinfection of rooms, a solution
of corrosive sublimate and tartaric acid in the proportion of 1 of the
former to 3 of the latter.
EaiL Desinfectante Larnaudes, sold in France, is a mixture of the
sulphates of copper and zinc. Vallin states || that this solution usually
contains only a little copper, and that when used as spray on walls,
and floors persons entering the room just after the operation notice
a marked cupreous taste and the styptic flavour of the zinc salt.
Vincent disinfects faeces and the contents of cesspools with acid copper
sulphate, using 6 kilos, per cubic metre per twenty-four hours.H
Cohn, in experiments on chicken cholera, considered sulphate of
copper and chloride of zinc superior to borax and chloride of lime.
But the German government have adopted neither of the former.
Verdigris (cupric acetate) is used as a wash for destroying the
parasites of plants, especially Feronospora in/esfans, the potato blight.
* Patent No. 11,641, 18S4. t Les Organismes, p. 289.
:J: Arch. exp. Pathol., voL iv., p. 1. § Lancet, 1889, vol. i., p. 144.
II Disinfectants, p. .62. IT Compt. Bend., vol. cxix., p. 965.
116 DISINFECTION AND DISINFECTANTS.
Still better is the copper-lime-sugai* wash of Michel Perrei.* These
and the sulphate are also used for soaking seed, corn, &c.
Fumigation with copper salts does not seem possible, but Clemens f
proposed a lamp filled with a solution of cupric chloride in alcohol
and chloroform, which when lighted is meant to give off vapours of
copper chloride. Reichardt f pronounced its use to be offensive,
poisonous, and variable. Clemens also sprinkled the straw, &c., in
stables infected with rinderpest with the same solution. For this it
would doubtless be efficient, but the expense would be very great, and
the animals must be removed.
Bona§ proposed a mixture of cupric sulphate and alum under the
name of " Cupralum."
lEON.
Metallic Iron has long been used as a purifying agent for waters
exposed to air. In water free from oxygen, carbonic acid, and chlor-
ides, pure iron can only rust by decomposing the water itself, forming
a crust of ferrous oxide which protects the surface, and liberating
hydrogen. If oxygen be present, the ferrous oxide rapidly turns to
red ferric hydrate, still giving a protective coating. But if carbonic
acid be also present in excess, it dissolves the ferrous hydrate as ferrous
bicarbonate, which in turn is oxidised to ferric hydrate, and the car-
bonic acid is again free to act on the iron, until the whole of the iron
is corroded and the ferric hydrate has deposited as an ochreous sedi-
ment, leaving the water almost free from iron. The action is hastened
if the iron contains other metals, through electrolytic action. Chlorides
of sodium, calcium, and magnesium are also partially decomposed,
nitrates reduced to ammonia, and sulphates changed to sulphide.^,
which are finally precipitated by the iron. The water thus becomes
alkaline, and if it contain organic matter, much of the iron remains
in solution. Water is thus liable to acquire a peculiar unpleasant
odour, due probably to hydrocarbons, and a styptic ferruginous
taste. The iron salts not only exert an antiseptic action of
moderate strength, but the ferric hydrate, like alumina, eifects the
removal of bacteria, and also in the same way "mordants" and pre-
cipitates the coleuiring and other organic matters present. If lime be
subsequently added, or it be filtered through carbonate of lime and
then aerated, it becomes colourless and very nearly pure. The treat-
ment increases the amount of ammonia present, if nitrates are present
in the original water. The hardness is not much affected. It is
* A. Girard, Comptes Bendv-i, 1892, vol. cxiv., p. 23 i.
t Deutsche IndiLHtriezeitung, 1 866, p. 268.
t Disin/ectionsmittel, 1881, p. 65. § Brit. Med. Joum., 1875, p. 239.
METALLIC SALTS. 117
advantageous to filter also through peroxide of manganese to complete
the oxidation.
Bischof's Spongy Iron Filter and " Carferal " * are applications of
this principle. Frankland proved that metallic iron exerts a special
destructive action on bacteria, and pointed out that though bacteria
prosper and multiply in sulphurous acid, cyanides, and other poisons,
they are, on the contrary, rapidly destroyed by metallic iron.t
Irving + causes the water to flow over metallic iron cascades, so as
to be at once exposed to the action of the metal and of air ; he then
filters.
Anderson has several patents for the agitation of water with scrap
iron or filings, or with spongy iron reduced from native oxides by
heating with carbon. In Patent No. 5,496, 1884, he suggests the use
of revolving cylinders, so that the iron continually falls through the
water, which passes in a slow current. § Nunn forces in air by per-
forated pipes under pressure. |1 An elaborate apparatus, with grids
and special means for cleaning the metallic surface, has also been
proposed.H
Bischof ** agitates sewage with spongy iron, allows it to subside, and
then assists the separation of the iron by aeration.
The water of the River Severn at Worcester has been purified in
this way by agitation with metallic iron. ft
Several patents do not reduce the oxide to the metallic state, but to
the lower oxide, re304. It must be remembered in the use of iron
that the metal itself cannot be in contact with the water, or there
would be the inevitable unpleasant taste and odour mentioned above.
The purification is due to the oxides, which act as carriers of oxygen
from the air to the organic matter present, and the core of metal is
intended to act as a i-eservoir of fresh oxides.
Magnetic CarbideW consists of iron ore, coke, and sawdust heated
together at a red heat in a gas muffle so as to form the oxide Yq.^0^.
The product is then extracted with dilute hydrochloric acid to remove
lime, kc.
Magnetic Spongy Iron as used for filters is made from carbonaceous
iron-stone (black band) by heating it in closed vessels until all vapour
ceases to be evolved.§§ It is also used for sterilising air|||| and for
* Patent No. 12,392, 1892. Joum. Soc. Chem. Ind., 1893, p. 539.
t Letter to the Engineers of the Municipal Council, Paris, 1881, p. 67 of their
OhHervations.
t Patent N'o. 8,056, 1884. § See also Patent No. 10,706, 1889.
II Patent No. 4,619, 1891. H Patent No. 14,735, 1891.
*• Patent No. 3,461, 1887. tt Trans. San. Institute, 1892, p. 309.
tt Rimmer, Patent No. 8,357, 1887. §§ Candy, Patent No. 1,793, 18i6.
nil Angell and Candy, Patent No. 14,999, 1887.
118 DISINFECTION AND DISINFECTAKTS.
precipitating sewage. In a later patent iron pyrites are roasted in air
and steam, the evolved gases (containing sulphurous acid) passed over
ferric hydrate, mixed with bauxite (jiative alumina) and the residue
lixiviated with water. The insoluble portion is then roasted with
coal tar, &c., short of the metallic state, crushed, and used with the
solution for sewage precipitation.*
Carferal (an abbreviation of carbon-ferrum-alumina), already men-
tioned, is similar.
Rusty scrap iron mixed with peat or wood-charcoal has been
protected by Cox and Cox t for the treatment of sewage.
Ferrous Sulphate, FeSO^, 7H2O, occurs in green crystals, soluble
in 1*6 parts of water.
All ferrous salts absorb oxygen from the air, becoming converted
into basic ferric salts which deposit as a rusty precipitate, and acid
ferric salts which remain in solution. Hence they act as reducing
agents. Owing to the formation of iron moulds, the iron salts are
inapplicable for the disinfection of clothing, &c. They deodorise fetid
liquids by absorption of ammonia and sulphuretted hydrogen, but at
the same time form a black coating of ferrous sulphide, which slowly
passes to brown basic ferric sulphate by absorption of oxygen. This
ferric coating can again absorb sulphuretted hydrogen, and again be
oxidised, and thus acts as a kind of perpetual deodorant. J
Virchow has pointed out one of the inconveniences of iron salts.
The volatile fatty acids, butyric, valeric, &c, which cause a part of
the offensive odour of putrefaction, are commonly combined with
ammonia. When iron salts are added the fatty acids are set free or
turned into unstable iron compounds, so that the immediate effect
of the projection of sulphate of iron into latrines is often an augment-
ation of the fetor; this soon decreases, but usually reappears after
a time.§ The same result would accrue on adding almost any acid
or acid salt, and thus, as well as for other reasons, it is necessary
to supplement the use of an acid or treatment with an iron salt by
lime. Lake,|| proposes "iron salt, then lime, then filter;" Lockwood,1I
'* iron salt, then hot milk of lime ; " and Conder ** uses ferrous
sulphate both for the treatment of water or sewage and for the pre-
servation of meat.
Deposits of sulphide of iron in sewers may be a source of danger,
since they are liable to produce sulphuretted hydrogen on the influx
of any acid liquid. An oxidising disinfectant like chlorine would,
• Candy, Patent No. 18,598, 1892. + Patent No. 1,259, 1886.
t Kuhlmann, quoted by Vallin, p. 62. § Ibid. , p. 63.
II Patent No. 3,953, 1884. % Patent No. 2,560, 1892.
•* Patent No. 6,459, 1885.
;
METALLIC SALTS. ]l9l9'
however, convert it into a sulphate and allow of its removal. All
reducing disinfectants are open to the following objections; (1) they
permit the reduced organic matters to be oxidised again by the air;
(2) they are themselves in great part at first wasted by the free
oxygen of the air and the water; (3) unless kept out of contact with
air they lose strength more or less rapidly by absorbing oxygen;
(4) the anaerobic bacteria are mostly reducing in their action and
flourish readily in surroundings deprived of oxygen, whereas free
oxygen is capable itself of killing them and destroying their food.
With many organic substances, e.g., tannin, iron salts produce a
black colouration and hence the French administration have pro-
hibited the use of iron salts where pavements or gullies can be dis-
coloured. In December, 1879, a Paris manufacturer recovered heavy
damages from a Disinfecting Company for stains on his materials
caused by careless disinfection by ferrous sulphate. Tallin significantly
adds (p. 755), "It seems that the disinfection was proved by the
evidence to have been quite insufficient whatever may have been the
quantity of sulphate of iron employed." Pettenkofer states that for
the disinfection of discharges it requires 25 grammes of ferrous sul-
phate per head per day, or about 1 in 400 on the quantity of excreta.
The strength of solution recommended is 28° Baume or about 37 per
cent, of crystallised ferrous sulphate.
Miquel classed ferrous sulphate as "moderately antiseptic," 11
grammes per litre being required to prevent putrefaction of beef
juice. This amount agrees closely with that proposed by Grace
Calvert, who advocated the use of a 1 per cent, solution.
The memorandum of the British Local Government Board, 1892,
says — "A substance generally available in the removal of filth from
privies and ashpits, and for application to foul earth and the like,
is sulphate of iron (green copperas), either in a strong solution made
by stirring the crystals with 5 or 10 times their bulk of hot water,
or in the form of powder, to which form the crystals may be readily
brought after desiccation.* This agent should be used in quantity
sufficient to destroy all odour f and in the removal of filth accumula-
tions it should be well mixed with successive layers of the matter
to be removed. It cannot confidently be stated that either the iron
salt or any available substance will effect a true disinfection of such
masses of filth as are here in question."
*6y this they lose water of crystallisation, which is nearly half (44 per cent.)
their weight, and become rather less easily soluble. If overheated a great loss
woald occur from oxidation and production of a basic salt. So that desiccation
is of very doubtful expediency.
tSee Virchow's remark, ante, p. 118.
120 DISINFECTION AND DISINFECTANTS.
The Society of l\redical Officers of Health have also recently
approved of ferrous sulphate for excreta.
The Belgian Government disinfect dejecta with ferrous sulphate
(or 2 or 3 per cent, carbolic), obtaining a supply by suspending a
bucket containing 50 kilogrammes in a cask full of water.
Germany, Austria, Sweden, and the United States do not officially
use it. In Jena a mixture of 1 part of the salt to 2 or 3 of ground
gypsum (which absorbs ammonia) is sprinkled oft the drains,* and is
called "Liider and Seidloif's Disinfecting powder." Candy f uses for
sewage the waste iron filings from aniline works dissolved in hot
sulphuric acid. This would give an acid mixture of ferrous and ferric
sulphate. KiddJ mixes ferrous sulphate 20 parts, with lime 4 parts,
and uses the wet precipitate with 1 pint of refuse soap for sewage
treatment. Bog iron ore without lime has also been suggested as
a mechanical precipitant, possibly acting as a feeble carrier of oxygen,
and a partial deodorant.
Harvey § proposes soda waste 1,000 lbs. to 1 million gallons of
sewage, then adding 62'5 gallons of burnt pyrites dissolved in hydro-
chloric acid, or practically a mixture of ferrous sulphate with some
ferric chloride. He states that the specific gravity of the solution is
1*275, and that the sewage is rapidly and effectively clarified. But
the effluent would be acid. Both and Lex || show that a mass of faeces
treated with a very strong solution of ferrous sulphate developed fungi
in abundance.
Ferric Sulphate, Fe.2(S04)3, in solution is brown and strongly acid.
It is moderately antiseptic, an imperfect deodoriser, and is open to the
same objections as ferrous sulphate, except that it is not a reducing
agent. It has recently been proposed as a cheap non-poisonous disin-
fectant. It gives precipitates with nitrogenous organic matters, and
coagulates albumen. Fresh urine treated with ferric sulphate yields a
precipitate containing 5-34 per cent, of nitrogen and 12*42 per cent, of
phosphoric acid. It may be conveniently obtained by the action of
sulphuric acid on burnt pyrites, but the solution would contain also
some ferrous sulphate in most cases. It has been manufactured into
briquettes, Fe.2(S04)3, OHoO, of a greyish pink colour, which are very
dense, and as compact as cement if mixed with plaster of Paris.
Phenolic briquettes are also made from 100 parts of ferric sulphate,
GO per cent., 5 parts phenol, and 16 of water.
Sacre and Grinishawll use the ferric hydrate obtained as a waste
product in the purification of zinc chloride as a cheap source for the
* Reichardt's Disinfection, 1881, p. 100. t Patent No. 19,587, 189*2.
X Patent No. 16,060, 1885. § Patent No. 6,994, 1889.
I! Handb. d. Militar., vol. i., p. 524. ^ Patent IS'o. 17,911, 1891.
METALLIC SALTS. 121
production of ferric chloride or sulphate, to be used to purify
sewage.
Wohanka and Kociau, of Prague, propose adding to ferric sulphate
(brown iron ore and sulphuric acid) lime, and afterwards water-glass
(silicate of soda). The patentees claim that such treatment destroys
the organisms in sewage. A clear effluent is obtained after filtration.*
Wolff grinds puddle slag containing 54 per cent, of iron with acids,
then adds chalk, and mixes with sewage. The sludge gives a manure,
and the effluent is stated to be clear and not to putrefy for months.
One cubic metre of waste water {e.g., from paper works) requires only
a few grammes.!
It is to be regretted that ferric sulphate, which could be so cheaply
made, is not of the value that the above statement would imply. It
does not kill bacteria unless it be of impractical strength.
Ferric Chloride, FcoCIq, is very soluble in water, giving a yellow or
brown strongly acid solution. In properties it resembles ferric sul-
phate, but is said to be slightly more powerful. It is a feeble oxidising
agent, absorbing ammonias and sulphuretted hydrogen. It checks
fermentation and the growth of bacteria without killing them, unless
it is concentrated. | With excreta it is apt to cause a very nauseous
odour. Wernicli gives a favourable account of its action as a precipi-
tant : — " Putrid and offensive material containing ammonium carbonate
cause a precipitate of iron oxide which carries down the suspended
matters; the supernatant liquid is clear, and both it and the precipitate
are inodorous, the sulphuretted hydrogen being removed as ferrous
sulphide and free sulphur, and the ammonia turned into ammonium
chloride." §
Sternberg says that it quickly paralyses the power of infection,
which, however, after a time revives.||
Drs. Hofmann and E. Frankland, in a report to the Metropolitan
Boai'd of Works in 1859, recommended chloride of iron for the deo-
dorisation of sewage, and found that to deodorise 7,500 gallons, l gallon
of perchloride of iron was equivalent to 3 lbs. of chloride of lime or
1 bushel of lime. The first of these kept the tank free from odour for
upwards of nine days, whilst the lime treatment broke down on the
third day, and that with bleaching powder after five days.
Vallin condemns it as a disinfectant.H It has no official recognition.
Nevertheless two English patents were taken out for its use iu 1892,
Nos. 13,316 and 15,235.
* Patent No. 278, 1887. t Wolff, Dingl. Pol. Joum., vol. cclxiii., p. 484.
+ Frankland and Ward's Second Report, Joum. Sac. Chcm. Iml., 1893, p. 1,052.
§ DiHin/ection'a Lehre, 1882, p. 180.
II Nat. B. o/Beahh, U.S.A., 1881, vol. cxL, p. 4 H Loc. cit., p, 65.
122 DISINFECTION AND DISINFECTANTS.
MANGANESE.
The metal is at present commercially unavailable for water purifi-
cation; it would act like metallic iron, but with greater energy.
" Ferro-manganese," an alloy containing up to 80 per cent, man-
ganese, and "Spiegeleisen" might be useful substitutes for iron in
water i)urification.
Peroxide or Dioxide of Manganese, MnOg, found native as Pyrolusite,
does not yield its oxygen to organic matters at the ordinary tempera-
ture. The precipitated peroxide (hydrated) is also sluggish. Candy
■asserts* that "sewage may be purified by agitation in a suitable
vessel with granular manganese dioxide, the average time of contact
being about five minutes." This statement seems to require confir-
mation, as it is difficult to understand how any purification other
than mechanical can take place under these conditions. If it be
heated strongly in closed vessels with carbon, a mixture of the
excess of carbon with lower oxides of manganese or perhaps the
metal itself is obtained. By this treatment the carbon is at the
same time purified and deprived of its hydrogen and any tarry
products which may be present. Such a preparation is much more
active as a carrier of oxygen than the similar one made with oxides
of iron (see ante, p. 117). Moreover it does not yield metal to
the water, as iron does. "Manganous cax'bon" was introduced by
Bernays.
This oxide when heated with hydrochloric acid is the ordinary
•source of chlorine —
MnOz + 4HC1 = MnCIa + 2H2O + CU.
As mentioned under the halogens, if it be heated with a chloride,
bromide, or iodide and sulphuric acid, it gives off the whole of the
<!hlorine, bromine or iodine. Such mixtures have been much used for
disinfecting rooms {ante, p. 57).
Manganous Salts. — Both the manganous chloride, MnClo, and the
sulphate, MnSO^ are slightly antiseptic. Miquel calls the former a
weak antiseptic since he required 25 grammes of it to prevent growths
in a litre of beef tea. Page considers that these salts are good disin-
fectants, but adduces no experiments in support of his conclusion.
Slater, Page, and others t proposed manganese chloride, and sul-
phate for sewage treatment, either alone or mixed with salts of
aluminium.
Chloride or sulphate of iron mixed with vitriol or hydrochloric acid,
manganese dioxide, or hydrated ferric oxide, and ground bauxite has
* Patent No. 15,391, 1891. . + Patent No. 3,973, 1886.
METALLIC SALTS. 123
been recently advocated for sewage treatment.* It is a mixture of
iron, manganese, and aluminium salts, possessing no apparent ad-
vantages.
Manganous salts as such may be excluded from the list of useful
•disinfectants, antiseptics, or even deodorants. They do not oxidise
on exposure to air, and, therefore, do not act as carriers of oxygen.
Even if lime be added, so as to precipitate manganous hydrate which
is re-oxidised by air, the action in presence of much water and organic
matter is unsatisfactory, and the expense would be great.
Manganates and Permanganates. — The manganates of the alkalies
are dark-green, unstable salts ; they are produced by fusing potash or
soda or their carbonates with manganese dioxide in the presence of
air, or with an oxidising agent, such as potassium or sodium chlorate
or nitrate. Impure sodium manganate, NaoMnO^, with much sodium
chloride, is known as " Condy's Green Fluid ;" it also contains some
permanganate (if barium chloride be added, the manganate is preci-
pitated, and the crimson permanganate is left in solution), and is
strongly alkaline fi*om excess of the base. It is a cheap oxidiser, but
as being impure and of varying strength, is much less used than the
permanganate. It spontaneously gives up 1 atom of oxygen with
great readiness, turning brown and turbid from the precipitation of
the hydrated peroxide thus —
2Na2Mn04 + 6H2O = 4NaOH: + 2Mn(OH)4 + Og.
If a dilute acid be added, even carbonic, it changes its colour to
•crimson, forming the permanganate, while hydrated peroxide is again
precipitated thus —
SKjMnOi + 2II2SO4 = KaMnjOg + Mn(0H)4 + 2K2SO4.
The decanted solution is nearly neutral, consists of permanganate
and sulphate, and is known as "Condy's Red Fluid." If evaporated
it yields crystals of permanganate, which are purified by recrystallisa-
tion. An application of this reaction is made in J. C. Stevenson's
patent f " acid sodium sulphate, ground with crude sodium manganese,
gives permanganate when dissolved."
Stevenson and Tatters I use dry sodium manganate 6 parts, bleach-
ing powder 3 parts; this yields a mixture of manganate, hypochlorite,
and chloride. Duprd and Hake § propose " a manganate with mag-
nesium sulphate or kieserite, calcium sulphate, zinc sulphate, or boric
acid. The manganate and one of these reagents are mixed in a dry
fine state of division."
Manganate of soda introduced into sewers in sufficient quantities
* Chem. Trades Jmm., Feb. 25, 1893. t Patent No. 2,739, Feb., 18S5.
t Patent No. 381, Jan., 1887. § Patent No. 4,283, 1887.
124 DISINFECTION AND DISINFECTANTS.
at different points, not only destroys organic impurity, but prevents
any noxious smells, and by further treatment at the outfall, the
effluent matter may be rendered "perfectly odourless, so as to be
discharged into streams with safety. Being strongly alkaline, it
disengages ammonia, which should be removed at the outfall by acid
treatment. Manganates have been employed by the Metropolitan
Board of Works, and by the London County Council, with fair
results. Vallin, on the contrary, asserts that sodium manganate is
almost inert. The amounts of available oxygen in two commercial
tiuids acidified by sulphuric acid, as determined by Allen in 1872,
were —
Green. Crimson.
Available oxygen in grammes per litre, 3'883 3921
Potassium Permanganate, KoMn.,Og, occurs in dark-red needles,
which are permanent in the air, and easily soluble in 15 or 16 parts
of cold water, giving an intensely crimson solution. In contact with
organic matter, when acidified with sulphuric aciiJ, it can furnish
5 atoms of oxygen —
KaMnaOg + 3H2SO4 = K2SO4 + 2MnS04 + SHjO + 50.
The solution should remain clear. If the acid be insufficient, a
brown precipitate of hydrated peroxide falls, and then only 3 atoms of
oxygen are liberated —
KjMnoOg + HaS04 + SHjO = K2SO4 + 2Mn{OH)4 + .30.
The progress of the reaction can thus be watched by the loss of
colour of the permanganate, the final point, when excess is reached,
being sharply indicated by the persistence of the pink colour of the
permanganate. Its disadvantages are : —
1. It leaves a brown stain on fabric?, and if concentrated it corrodes
them.
2. Like chromic acid, it must first expend itself in oxidising sul-
phuretted hydrogen, nitrites, ferrous salts, and most organic matters,
before attacking organisms, which are so resistant to it that Koch
states * that it is applicable only in concentrated solutions (5 per cent.)
Miquel puts it in the third class of disinfectants, requiring 3"5 grammes
to sterilise 1 litre of beef tea. Calvert, on the other hand, found that
1 in 125 "prevented animalcules in beef juice and albumen for six
days." Hankin considers it a specific for cholera bacilli, f
3. Not being volatile, it can only act locally. Condy in 1859
proposed its employment for air-disinfection by hanging up sheets
saturated with the solution, by sprinkling walls, and by exposing
layers of it in dishes in infected rooms. By such procedure a large
quantity of air must escape contact with the liquid.
* MUlh. a. d. hats. Ges., Dec. 3, 1881. t Brit. Med. Jturn., Mar. 16, 189.5.
METALLIC SALTS. 125
The solid when treated with strong sulphuric acid gives off ozone,
but the reaction is a violent one, and is dangerous in inexperienced
hands.
Deniarquay spoke favourably of it for surgical use in a solution
containing 1 in 1,000, as disinfecting very well, and as hardly irritant.
But its action is ra[)idly exhausted, and it does not prevent the secre-
tions from retaii;iing their virulence, and Vallin is of the opinion that
it is of more value as an immediate deodorant than as a destroyer of
virus.* This statement has since been corroborated by Blyth,f and
by Klein.J
4. Permanganates do not absorb ammonia, and do not attack urea
nor fatty acids.
Condy and Mitchell's original patent has long expired. In 1877
the former invented a very ingenious contrivance with vertical threads
hanging close together in a ring, down which a solution of perman-
ganate trickled from a circular basin above to a similar one below.
This, of course, could be applied to other disinfectants ; with volatile
ones it would be more effective.
Among the numerous patents covering the application of perman-
ganates for disinfecting purposes are : — Reidemeister of Magdeburg,§
"Small quantities of potassium permanganate and peroxide of hydrogen
are added to water when a bulky precipitate forms, carrying down
all suspended matter and the smallest organisms, while oxygen is
evolved."
Tweedie and Hartin's " Crimson Salt " || is 1 part of potassium
permanganate, 8 of potash alum, 1 of borax, 6 of sodium chloride.
H. B. Condyll proposes the use of the aluminium salt " In 1,000 parts
by weight of a 33 ]>er cent, solution of aluminium sulphate, dissolve
53 of potassium permanganate by heat. On cooling, i)Otash sulphate
alone crystallises out, leaving permanganate of alumina and excess of
aluminium sulphate in solution."
Lumps for closets containing the following mixture have been
proposed : — Boric acid 10, salicylic acid 10, potassium pennanganate
40, potassium or sodium silicate 40, made into a hard mass.** Meyer
uses " Dry powdered barium permanganate 25 parts, to sodium bi-
sulphate 16 parts, mixed in the dry state; an inert body like bariiim
sulphate may be added to give bulk. If sufficient water be added to
form a thick syrup, ozonised oxygen will be evolved." ft
* Vallin, TraiU, pp. 325-328.
t " Studies of Disinfectants by New Methods," Proc R. Soc., 1886,
t Stevenson and Murphy's Ilyffiene, 1893, p. 01. § D. Patent, July, 1882.
II Patent No. 9,538, June, 1884. H Patent No. 10,015, 1S84.
*• J. Soc. Chem. /ud.,.1890, p. 98, tt Patent No. 16,463, 1S3S.
126 DISINFECTION AND DISINFECTANTS.
Hamilton* fuses potassium chlorate, manganese dioxide, and
potash, saturates the solution with carbonic acid, and crystallises.
This is simply an old method of 'making permanganate. He then
mixes it with borax.
"Taylor's Roylat Disinfector" is an ingenious contrivance for
liberating the liquid in cisterns automatically. Stoneware bottles
are filled with permanganate and hermetically closed, with the ex-
ception of a small glass tube which reaches to the bottom. The bottle
is inverted and placed at the bottom of the cistern. When the latter
empties some strong solution flows out.f
" Condy's powder " contains a small proportion of alkaline perman-
ganate and has no smell. |
Disinfecting tablets or blocks have been proposed by Thornton.§
They are "prepared by mixing potassium permanganate or other
disinfectant, paraffin wax, sulphate of calcium, or any other suitable
cement, with some absorbent material, such as asbestos, cotton yarn,
pumicestone, cinders, &c.
" Permanganate of potash is mixed with plaster of Paris or other
cement or plaster, and cast into bricks or balls or into perforated tin
cases, the object being to economise the permanganate."!
One or two patents propose to recover the manganese or iron oxides
precipitated in the sludge in sewage treatment, by pressing the latter,,
adding more ferric or manganese oxide, if necessary, heating in a
closed retort, utilising the ammonia and evolved gases, cooling out of
contact with air, and using the mixture of carbon with metallic oxides
as a filtering medium. U The process, however, is not economical, as
there is so much water to remove, and the product is of very inferior
value,
M'Dougall calculated that "at the commercial price of Condy's fluid
in his time, it would cost £10,400 per annum to disinfect with per-
manganate the typhoid stools of a hospital having an average of 30
cases." Crystallised permanganate has since been much cheapened,
but the cost yet remains sufficiently formidable to prevent its ex-
tended use, and, as already pointed out, its applications are somewhat
restricted.
•Patent No. 6,571, 1887.
t Cy., "A similar Method for Cisterns," by B. S. Proctor, Chemist and Druggist,
April 28, 1894.
X Lancet, 1887, p. 683. § Patent No. 17,421, 1891.
II M. Syer, Patent No. 11,049, 1892,
IT Wilson, Patent No. 17,275, 1891, and others.
METALLIC SALTS. 127
CHAPTER VII.
METALLIC SALTS {continued).
Aluminium Salts : Use in Sewage Precipitation — Alums — Aluminium Chloride
— "Chloralum" — Acetate — Sulphites — General Character of the Salts.
Chromium : Chromic Acid — Potassium Bichromate. Arsenic : Arsenious
Acid — Arsenites — " Paris Green " — Arsenic Acid — Prohibition in France.
Lead and its Salts : Nitrate and Acetate. Mercury : Oxide and Nitrate
— Corrosive Sublimate; its power as a Disinfectant— Applications — Iodide
— Mercuric Iodide Soaps — Cyanide — "Zinc Mercuric Cyanide" — Objections
to Mercury Compounds — Organic Mercurials. Tin: Stannous Chloride.
Bismuth: Subnitrate — "Dermatol." Silver: Nitrate of Silver — Osmic
Acid. General Remarks on Disinfectants.
ALUMINIUM.
The soluble salts of aluminium generally are powerfully astringent,
acid, styptic to taste, and in solutions of moderate strength are not
poisonous. They also produce no stain on fabrics, do not act upon
metals, and are iriexpensive. On addition of lime or ammonia they
give a bulky flocculent precipitate of hydrated alumina, carrying down
mechanically with it not only the solid matter in suspension and any
germs that may be present, but also much of the dissolved organic
matter, forming more or less definite combinations analogous to the
"lakes." They have therefore been most extensively tried for sewage,,
both alone and with iron salts, lime in most cases being added. The
effluent by this treatment is in most cases found to be clear, nearly
colourless, apparently sterile, and deprived of most of its odour^
Unless an equivalent of lime or ammonia is present, the effluent is
acid and has an injurious influence on fish. The precipitate or "sludge""
should include all the phosphates, most of the nitrogenous matter, and,
since it contains no poisonous disinfectant, be available commercially
as manure.
The antiseptic power of the alums and of aluminium sulphate, the
forms most commonly used, is only slightly greater than that of the
sulphuric acid they contain, and most authorities are of the opinion
that when these salts are used in sewage treatment the germs are not
entirely removed; a few escape precipitation and soon commence to
multiply afresh ; consequently the effluent again becomes foul, and
on being diluted by passing into rivers, is capable of contaminating
immense volumes of water. That the whole of the river is not polluted
128 DISINFECTION AND DISINFECTANTS.
is due to the fact that " purified " sewage does not readily mix with
ordinary water, but flows on for long distances in a separate stream.
The "sludge" also becomes quickly offensive in warm weather.
Eepeated attempts to utilise it as manure, by straining, pressing,
drying, and even fortifying with phosphates, &c., have hitherto met
with only partial success.
Attempts to burn it for cement, utilising the ammonia and other
^ases evolved, have also been made. The great difficulty is the
removal of the water, which gives in drying, and still more in burning,
offensive vapours.
The following is a brief summary of the processes that have been
tried for sewage precipitation, of which many involve the use of
aluminium salts : —
1. Lime Process. — The First Report of the Elvers Pollution Commis-
sion, vol. i., p. 52, pronounced it a failure.
2. Lime and afterwards Ferric Chloride.
3. Ferric Chloride alone. — Too expensive.*
4. Zinc and Manganese Salts. — Unsatisfactory.
5. M. and C. Process, 1875.
6. General Scott's Sewage Cement process, 1872. Lime and Clay. —
Abandoned.
7. mile's Method. — 100 lime, 6 tar, 12 calcined magnesium chloride
(mother liquor of sea water). Expensive. Sludge useless. Water
deodorised, but bad.
8. Black Ash ^Vaste.J — This material must be free from calcium
sulphide — i.e., must be old and oxidised to thiosulphate. Its use has
not met with any degree of success.
9. Jili/th's. — Superphosphate of magnesium, to add to the value of
the sludge as manure.
10. llolden's. — Ferrous sulphate, lime, and coal-dust or clay. 1868.
1 1. David Forbes' PJiosphate Method. — Described under "Acids" (p.97).
12. Whitthread's Patent, 1872.
13. Bird's Process. — Crude aluminium sulphate, obtained from
pulverised clay and strong sulphuric acid, which are heated together^
and the mass allowed to settle, and then filter through coke. The
•effluent is acid.
14. Stothert's. — Aluminium and zinc sulphates and charcoal, then lime.
15. The well-known A. B.C. Process. — " Alum, blood (freshly drawn),
clay, charcoal, some compound of manganese, and various other ingre-
dients in smaller proportions." Tried on the large scale at Leamington
in 18G7. Unfavourably criticised by the Eoyal Commission of 1870.
* Second Report of Setoage of Tovms Commission, pp. 17 and 72.
t Hanson, Roy. Comm. of Metr. Sew. Discharge, vol. xi., p. 97.
METALLIC SALTS. 129
IG. Anderson's. — "The sewage, after subsidence, is agitated with a
saturated boiling solution of crude aluminium sulphate, then milk of
lime, then filtered through soil into the river." The effluent is not
pure, the cost is great, and the manure of little value (Corjield).
17. Lower Thames Valley, 1884. Aluminium and Ferrous Sul-
2}}uites, and Lime. — Rejected by a Committee of the House of
Commons.*
18, Wimbledon Process. — Spence's " aluraino-ferric " (composition,
Al.jOy, soluble 14 per cent.; FeoO.,, 0*75; SO.j, 33-81; free acid, none;
water, 51 "44) is used with lime. In very hot weather, sodium man-
^anate is used in addition, to prevent the setting up of secondary
fermentations, and the production of offensive odours when the sewage
is applied to the land. The manganate is dissolved in warm water,
and is added to the clarified sewage in the settling tanks in the pro-
portion of about 2 grains per gallon. Nearly every known reagent
has been tried at Wimbledon, but up to the present the above has
been found the best.
During the Royal Commission to investigate the conditions of the
Metropolitan Dis(;harge,t Mr. Dibdin pointed out that it is possible
to thoroughly deodorise the sewage by means of potassium perman-
ganate and sulphuric acid (giving ozonised oxygen) either before or
after the removal of the suspended matters by precipitation. Large
quantities of sodium manganate are now used for this purpose, which
salt seems at present to be the only one of value, but the cost is
considerable. Ferrous sulphate also remains in favour. Obviously
the two cannot be used together, as one being an oxidising and
the other a reducing agent, they would destroy one another.
Parkes and Corfield summarise as follows: — " All to a certain extent
purify the sewage and prevent the pollution of rivers, chiefly by
removing the suspended matter, but they all leave a large amount of
putrescible matter in the effluent, and at least all the ammonia." IMost
of the phosphoric acid is also precipitated, and in many of the processes
the hardness of the water is increased.
A multitude of patents exist which have been taken out for slight
variations in the use of blast-furnace slag, clay, or shale alone, either
raw or burnt, or the products of their treatment with acids, yielding
crude salts of aluminium and iron, with lime, peat, charcoal, coke, «kc.
One or two examples may be noticed : — In Patent No. 2,068, 1882 :
" Cannel coal broken small with 10 per cent, of alumina, preferably as
aluminous clay or brick earth, coked in a kiln," is used as a deodorant.
In Patent No. 13,7G1, 1885 : "Native aluminium phosphate dissolved
• See a paper on Sewage disposal, Soc. Med. Off. of Health, 1884-5, by Dr.
Stevenson. t Vol. xi., p. 142.
9
130 DISINFECTION AND DISINFECTANTS.
in acid, and the same substance dissolved in soda are added succes-
sively to the sewage. The acid and alkali neutralise one another, and
the whole of the phosphate is precipitated." Unfortunately, phosphate
of alumina is so soluble that it is the least useful phosphoric salt for
manure. Similarly it is proposed to add sodium aluminate to acid
aluminium sulphate.*
Kruger,t after stating that Bolton, Hueppe, and Frankland's experi-
ments are not entirely exclusive, details his examination of the action,
of clay, carbonate of lime, kieselguhr, alumina, brick-dust, charcoal^
coke, and sand, on sewage. He points out that finely-divided, chemi-
cally inert substances, when introduced into water, take down with
them the greater part of the bacteria present. The action is more
intense the slower, within certain limits, that the deposition takes-
place, and the greater the quantity of precipitant supplied.
He gives another series of experiments with chemical agents, in-
cluding aluminium sulphate. The sterilisation is far greater when, in
addition to the merely physical deposition, a chemical precipitation
supervenes. In the purification of sewage water, therefore, preference
should be given to chemical treatment, and inert substances should
merely be regarded as mechanical aids.
Leeds 1 states that half a grain of alum per gallon reduced the
micro-organisms from 8,100 in 1 c.c. to 80.
Y. and A. Babes found that 02 gramme per litre after twelve hours-
carried down all the microbes from a water containing 1,200 per c.c.^
and the supernatant liquid was sterile. The sediment also contained
from 20 to 100 living bacteria, whereas the untreated water had 1,500
to 6,000.§
A report by Lepoins, published by the Frankfort Commission on
Sewage, 1891, states as follows : — "The eflfect of chemical precipitation;
is not so greatly superior to the purification obtained by simple de-
position in tanks, as to warrant the adoption of any of the above
processes in preference to simple mechanical treatment."
The result of trials at the St. Lawrence Experimental Station In
Massachusetts has shown that "a mixture of lime and aluminium
sulphate has little to recommend it."
Sir R. Rawlinson || remarks, " To disinfect the sewage of the
Metropolis would cost millions per annum, and, according to Dr..
Parkes, the most powerful disinfectants would not give safe results.
* Clarification ' may be accomplished temporarily by chemicals, but
* Maxwell Lyte, Patent Nos. 900 and 6,054, 1885.
+ Zeit. f. Hyg., 1889, p. 86. X Potable Water, Boston, 1891, p. 86.
§ Centr.f. Bakleriol., 1892, vol. xii., p. 132,
II Joum. Soc. Arts, vol. xxxviii., p. 65.
METALLIC SALTS. 131
will not then produce permanent purity. It will cost £1,500 to
£3,000 for each million gallons per diem, and even the less amount
will reach £225,000 per annum for the Metropolis, while expenses
will raise this half a million." Notwithstanding, patent 24,080, 1892,
proposes " to sterilise water without filtration by adding alum, 1 to 2
per 1,000, and leaving to settle for twelve hours."
At Glasgow aluminium sulphate and lime, with filtration through
coke, gravel, and sand, and subsequent aeration is employed before
the water effluent passes into the Clyde.
Aluminium Chloride, AlgClg, occurs in white crystals, very sol-
uble in water, strongly acid, non-poisonous, but powerfully astringent
when diluted ; it absorbs ammonia and compound ammonias, but not
sulphuretted hydrogen, therefore it is only a partial deodorant. It
is more antiseptic than the sulphate, and still more than alum.
Miquel gives the minimum for sterilising a litre of beef tea as Al^Clg
1'4, potash alum, 4-5 grammes, as compared with mercuric chloride
0-07, copper sulphate 0-9, and zinc chloride 1"9, so that its behaviour
is intermediate between copper sulphate and zinc chloride. It is a
good local disinfectant when strong.
Slater and Stevens* dissolve "Gibbsite" or any aluminium com-
pound containing, a considerable proportion of hydrate of alumina in
hydrochloric acid. The acid solution is used for sewage, preceded by
lime, with the addition of clay and charcoal ground up together.!
Again, J Slater and the "Native Guano Company" add " clay, crude
aluminium chloride, and other substances to sewage." The use of slag
and hydrochloric acid have also been patented by Slater.§ In another
patent crude aluminium and iron sulphates from shale are mixed with
calcium chloride, yielding aluminium chloride and calcium sulphate,
the latter being used for manure.
Chloralum was the title given to a disinfectant much advertised in
England for some years, but now f^lmost disused. Fleek, of Dresden,
states that it contains chlorides of aluminium, lead, copper, iron, and
calcium of various amounts.
Wanklyn || pronounced it to be a deo<lorant superior to chloride of
lime. M'Dougall by experiments maintained that it arrested putre-
faction and prevented the growth of organisms more than other
antiseptics. He recommended it for washing infected matters, for
disinfecting sewers and the soiled linen of hospitals. But O'Neill's
experimentsIT tended to show that neither chloralum nor chloride of
* Patent No. 15,810, 1884. t See also Patent No. 16,592, 1894.
t Patent No. 17,453, Oct., 1S90. § Patent No. 12,830, 1884.
\\ Brit. Med. Journ., "Action and Relative Value of Disinfectants," 1873,
p. 275. IT Army Med. Report, 1871.
132 DISINFECTION AND DISINFECTANTS.
aluminium itself arrested putrefaction. " Even on adding 1 part of
chloralum to 2 parts of organic matter, animalcules were abundant on
the fifth day, and a putrid odour Vas distinct on the seventh day.
Aluminium chloride was slightly better, as the odour was delayed
to the tenth day, with 1 part in 6 or 8. Vallin states that
" Cupralum," a mixture of alum with copper salts, has aimed at re-
placing "chloralum," but with no greater success.
Aluminium Acetate has been much praised by Barow, Kuhn,
Wernitz, and Jalan de la Croix. It would doubtless be useful for
surgical dressings, but is unnecessary and unsafe as a disinfectant.
Maas recommends a 2-5 per cent, solution for surgical work.
Aluminium Sulphites have been recommended by Wade as non-
poisonous and non-irritating antiseptics.*
CHROMIUM.
Chromic Acid, CrO.j, is a powerful oxidiser, and instantly coagulates
albumen. It combines with a great many organic compounds, pro-
ducing brown or yellow substances. This staining or mordanting
action causes it to kill bacteria by an action on their envelopes.
It i-anks with the halogens, nitrate of silver, and permanganate, in
its special action both as an antiseptic and disinfectant. Its cost
and poisonous and corrosive nature have excluded it from the list
of useful disinfectants.
Potassium Bichromate, K^Cr^O-, is similar, but less vigorous, in
its properties.
The earlier investigators made many experiments with these two
agents. M'Dougall t in experiments on vaccine and other virus,
found that 1 in 2,200 of chromic acid " prevented animalcules "
in infusions for six days, 1 in 500 for seventy-eight days. O'Neil |
using beef juice, states that with 1 in 120 of bichromate of potash
*• there were no signs of decomposition in twenty-four days, with
1 in 150 a great number of animalcules appeared on the eleventh
day ; on the twenty-fourth day there was still no really disagreeable
odoui'." Davaine§ found that the virus of anthrax and septicaemia
was definitely destroyed by 1 in 6,000 (anthrax) or 1 in 3,000 (septic-
aemia) of chromic acid. These experiments are of no real value (Klein),
since the conditions are inexact and are not those of actual practice.
Lanjorrois |1 to 500 cubic centimetres of urine and blood added
5 grammes of bichromate, and found that in eight months there was
* Pharm. Kecord, Nov. 1, 1888. t Med. Times and Oaz., 1872, p. 485.
X Army Med. Ueport, 1872, p. 202. § Qaz. Med., 1874, p. 44.
II Chem. Centr., CI., 1884, p. 676.
METALLIC SALTS. 133
no putrescence. He does not say whether any coagulation of the latter
occurred. Milk with 1 per cent, of bichromate remained unaltered
for three months. But owing to its poisonous action a bichromate
cannot be used as a preservative.
Kidd has patented a mixture of potassium or sodium bichromate,
or chromic acid, with a little sulphuric acid, for disinfecting sewage.
Even if efficient, the expense would Le prohibitive.
ARSENIC.
Arsenious Acid, As.,0.,, is a white powder, slightly soluble in
water (about 1 in 1,000), giving a feebly acid and almost tasteless
solution which is yet strongly poisonous. It dissolves, however, very
easily in alkalies forming arsenites. It is also soluble in hydrochloric
acid as arsenious chloride, or " liquor arsenici hydrochloricus.'"' The
latter is to be preferred as it has the additional antiseptic properties
of a solution of hydrochloric acid.
These compounds are deodorants, as they absorb sulphuretted hydro-
gen and compound ammonias.
Although arsenic is so powerful a poison to higher animals and
insects, it has little effect on lower forms of life.* Miquel ranks
AsoOj as '•' moderately antiseptic," requiring G grammes per litre to
prevent growth in beef tea.
" Gannal's solution," formerly used in France for injecting corpses,
contained 21 grammes of As^O., and 1,000 grammes of aluminium
sulphate per litre. Seed-corn was often sprinkled with As^O^ before
sowing, to kill fungi and insects. Copper sulphate is much better and
safer for this purpose.
Potassium Arsenite, " Fowler's solution,' and Sodium Arsenite, have
long been employed as " Sheep-dips," for killing insect parasites.
Robertson patents the following preparation t : — " 3 of rosin, 1 of
grease melted with 6^ tar oil (containing 25 per cent, tar acids), and
2 of 95 per cent, phenol. Add 2 of arsenious acid dissolved in
1^ per cent, soda-lye, or an equivalent quantity of arsenic sulphide
may be used. The product is soluble in cold water, and has the
properties of a simple carbolic dip and an arsenic dip, the tar acids
coagulating the parasites, and the arsenic having a continuous
poisonous effect on their progeny."
Acetoarsenite of Copper, " Paris Green," contains 28-5 per cent, of
arsenic and 32 per cent, of copper. It is insoluble, but is one of the
best agents for killing insects on trees, sprayed over them in the pro-
portion of 1 ounce to 10 gallons of water.
• Frankland and Ward, Journ. Soc. Chem. Jnd., 1893, p. 1,053.
t Patent No. 2,990, 1893.
134 DISINFECTION AND DISINFECTANTS.
Arsenious Sulphide, AsgSg, dissolved in alkaline sulphides, is used
in tanning to prevent fermentation and putrefaction. But S. Sadlou
says * that common salt, together with an alkaline sulphide, will
produce the same result.
Arsenic Acid, HgAsO^, is much more soluble, and reputed to be
more poisonous, than arsenious acid. But neither it nor the arsenates
are of any value as germicides. Miquel states that the potassium salt
is "very feebly antiseptic," requiring 125 grammes per litre to prevent
growth in beef tea, while sodium arsenate is " moderately antiseptic,"
requiring 9 grammes per litre. f Loew J remarks that "the acids of
arsenic are poisonous towards algae only in the same degree and for
the same reason as are acetic and citric. Larvjse and infusoria live in
a 1 per mille solution of potassium arsenate, though higher animals
die."
In France the use of arsenical compounds as antiseptics has been
totally prohibited since 1876.
Considering the ease and rapidity with which arsenic is diffused,
and the insidious action, even of traces, in water, food, or air, even if
it were a good antiseptic, its use should be penal in all countries.
LEAD.
Lead salts absorb sulphuretted hydrogen, ammonia, and their
derivatives, and are therefore deodorant. Measured by the amount
required to sterilise a litre of broth, Miquel classes them as "strongly
antiseptic," only slightly below zinc chloride, where 1*9 grammes of the
latter is used, 2 grammes of lead chloride, or 3-6 grammes of lead
nitrate, are required.
Nitrate of Lead, Pb(N03).„ is the basis of a "disinfectant" long
known under the name of "Ledoyen's liquid," composed of 1 part of
the salt in 10 of water. M. Fermond in 1858 used it in the closets of
the Saltpetriere, and found it was effective in removing the odour, as
other metallic salts would be, but it had the disadvantage of being
easily precipitated as lead sulphate, and of covering the basins with a
black coating of lead sulphide. It is expensive, and does not absorb
ammonia readily. It is inapplicable for wounds, on account of its
ready absorption and poisonous effect on the system.§
Basic Acetate of Lead, or "Goulards' Extract," is used for burns
and bruises, but only for its cooling qualities.
In conclusion, lead compounds are of no value as disinfectants.
* Der Gerber, 1891, vol. xvii., p. 284.
t Les Organinmes, p. 289.
i Centr.f. Agric. Chem., vol. xiii., p. 68.
§ Vallm, D6smfectant8, 1882, p. 66.
METALLIC SALTS. 135
COMPOUNDS OF MERCURY.
Mercuric Oxide, HgO, like insoluble substances generally, has no
action by itself on organisms, but it easily dissolves in even vegetable
acids to form many soluble, and therefore active, salts. Admixed or
combined with phenol it has been used for a '* earbolate of mercury "
soap, which, according to Dr. Woodhead,* is not a valuable preparation.
Combined with oleic acid it forms a strongly anti-parasitic basis for
ointment. Oleate of mercury is in the British and most other phar-
macopoeias.
Mercuric and Mercurous Nitrates are strongly antiseptic soluble
salts, but are not used because they are caustic and are easily decom-
posed by a large quantity of water. ** Unguentum Hyd. Nitratis "
is a parasiticide.
Mercuric Chloride, HgCl2, perchloride of mercury, or "corrosive
sublimate," is probably the most powerful disinfectant we possess.
It will be seen that the poisonous action of a great number of anti-
septics depends on their property of precipitating albumen and other
allied ingredients of protoplasm. For example, phenol, mineral acids,
copper and iron salts, alum, tannin, chromic acid, all form insoluble
compounds with ^Ibumen. Mercuric chloride possesses this property
in a very marked degree, but the compound produced re-dissolves in
excess of albumen. It is, therefore, necessary to have mercuric chloride
present in excess. Mercuric chloride is soluble in 15 parts of water,
and still more in alcohol, ammonium chloride, sodium chloride, and
dilute acids. It is exceedingly poisonous, a dose of 2 centigrammes
■daily soon producing poisonous effects. This almost prevents its use
internally, and even makes its external employment dangerous. Hence
solutions of it used for disinfection should be coloured, preferably blue.
In the United States it is recommended to add an equal quantity of
potassium permanganate to distinguish the solution. As to the
efficiency of mercuric chloride, the earlier investigators gave varying
but very high results. Bucholtz, in a comparative list of the amounts
of different disinfectants required to suppress the gi'owth of bacteria
in culture solutions, places mercuric chloride in the foremost place,
and recommends a solution of 1 in 20,000.t Miquel says that a
solution of 1 in 14,000 is disinfectant, and Sternberg 1 in 30,000.
Koch asserts that "a single application of a solution 1 in 1,000 or even
1 in 5,000 is sufficient to destroy the most resistant organism in a few
minutes ; with a longer exposure it only begins to be unreliable at
1 in 20,000." J Davaine§ stated that 1 in 15,000 killed anthrax.
* B. M. A. Reports, 1888. t Archie, f. exp. Pathol., vol. iv., p. 80.
X Mittheil. a. d. k. Oesund., 1881, p. 234.
§ Bull, de I' Acad, de Med., July, 1880.
136 DISINFECTION AND DISINFECTANTS.
Vallin says that 1 in 2,500 is effective under most unfavourable cir-
cumstances.* Billroth, Haberkorn, iind Kuhn likewise recommend it.
Therefore, though it cannot be employed for preserving food on account
of its poisonous nature, it has been used for injecting corpses and by
most governments for local disinfection. Dr. Collingridge, in a private
communication informs me that for ships' crew's spaces, rooms, &c.,
after fumigation by sulphur either by the ordinary process of com-
bustion or by the liquid sulphurous acid, he washes with a solution of
mercuric chloride of 1 in 2,000. Vessels entering the Mississippi
suspected of contamination are sprayed over all surfaces excepting the
cargo with a solution of 1 in 1,000.1 The hold is then disinfected
with sulphur. Since mercuric chloride is non-volatile at ordinary
temperatures, it cannot affect the air throughout the spaces, hence it
only acts as a strictly local disinfectant.
But Klein has very much reduced the above too favourable estimates
of the power of this salt. He considers it an efficient germicide, but
maintains that Koch and others have overrated it. In 1885 Blyth
conducted a series of experiments in which he treated anthrax spores
with 1 in 1,000 solution of mercuric chloride, as others had done, when
he noticed that the bacteria were apparently killed and the spores
ceased to develop ; but on then inoculating guinea-pigs with the
appai'ently sterilised infusion, anthrax rapidly appeared, the animals
died, and the blood was swarming with Bacillus antliracis. He con-
cludes that a solution of 1 in 1,000, although it kills the non-spore-
bearing organisms, only stupefies and does not destroy the sjjores of
Bacillus anthracis.X Dr. Woodhead§ explains Klein's x'esult as due to
the precipitation of the mercuric chloride by the albumen present,
" which gave a coating or pellicle of albuminate of mercury round the
spores, protecting them from further action until they were introduced
into the blood of the animals, when the excess of albumen re-dissolved
the pellicle and set the organism free to flourish in its new surround-
ings."
Grace Calvert also pointed out, many years ago, that mercuric
chloride "destroys vibrios but not fungi;" and H. Schulz|| has shown
that a solution of 1 in 500,000 increases the activity of Saccharomyces
cerevisice.
Koch has repeated his experiments and somewhat modified his
earlier conclusions. He still affirms that mercuric salts, especially the
chloride, are most valuable. " For a ship's bilge, where a 5 per cent.
♦ Traite, p. 117. t Pharm. Journ., 1887, p. 144.
t Micro-organisms of Disease, 1886, p. 261.
§ Proc. Boy. Soc. of Edinburgh, vol. xv. , p. 246.
II PJluger's Archiv,, voL xlii., p. 517.
METALLIC SALTS.
137
solution of carbolic acid must be left for forty-eight hours, a 1 in 1,000
mercuric chloride solution only required a few minutes." He admits
that " there is on the other hand reason for doubting the efficacy of
this salt, for though anthrax spores subjected to a 1 in 20,000 solution
for ten minutes and then washed in alcohol gave no growth in nutrient
gelatin, silk threads infected with the spores and then exposed for ten
minutes to a 1 in 20,000 or even 1 in 10,000 solution proved fatal to
mice." *
Herroun considers that the value of this substance as an antiseptic
has been very much overrated, as he has cultivated ordinary septic
bacteria in albuminous filtrates containing 1 in 20,000 of mercuric
chloride. " It is precipitated by albumens if used in greater strength^
and is readily converted by the sulphur of all bodies into insoluble
mercuric sulphide which is practically inert." It may be remarked
also that mercuric chloride is precipitated by any alkaline solution such
as ammonia, &c. Laplace in a series of experiments found that 5 c.c,
of blood serum was sufficient to precipitate the mercury from 5 c.c. of
a solution of the strength of 1 in 1,000, but that by adding hydrochloric
acid in the proportion of 5 in 1,000 the formation of the precipitate is
prevented. Similar results are obtained when tartaric is substituted
for hydrochloric acid.f When about 10 parts of sodium chloride are
added to 1 of mercuric chloride, the coagulation of the albumen is also
prevented.
It may be concluded that Klein's results are confirmed, and that
Woodhead's explanation is at any rate part of the truth. It follows
that the minimum must be raised to 1 in 500, and that the solution
should be aciditied, preferalily with about ^ per cent, of hydrochloric
acid, which adds much to the antiseptic power. If, as already men-
tioned, permanganate is used with it, or some colouring matter like
indigo or aniline blue be added, the advantage of the warning colour
is obtained. In the United States mercuric chloride is held in great
esteem. Dr. Mead Bolton J gives the following table of the minimum
strength required of various disinfectants : —
Organism.
Chloride of Lime.
Mercuric Chloride.
Carbolic Acid.
Typhoid bacillus,
Cholera spirilluni,
Anthrax spores,
Staphylococcus aureus,
, , citreun,
„ albus.
1 in 2,000
1 in 2,000
1 in 100
1 in 200
1 in 50
1 in 200
1 in 10,000
1 in 10,000
1 in 1,000 (?)
1 in 100
1 in 100
1 in 50(?)
(Incertain.)
1 in 100
1 in 1(0
1 in 100
• Crookshank's Bacteriology, 1887, p. 150. t Brit. Med. Journ., 1888, p. 148.
+ Report ofComm. on Disinfectants of Amer. P. If. Aanoc., 1889, p. 236.
138 DISINFECTION AND DISINFECTANTS.
The American Public Health Association recommend a solution of
1 in 500 of mercuric chloride to be used for spore-coutaining infected
material, and 1 in 2,000 for that which does not contain spores, as
compared with 5 per cent, carbolic or 10 per cent, zinc chloride.
Hands are washed in a 1 in 1,000 solution. The dead are wrapped in
sheets saturated with 1 in 500 ; walls are washed with 1 in 1,000, and
ships sprayed liberally with the same strength.
The French authorities adojit a solution containing 1 gramme of
mercuric chloride and 3 of tartaric acid in 500 of distilled water for
■disinfecting rooms (Laplace's formula).
In Paris, spraying rooms after infectious disease with a 1 in 1,000
solution of mercuric chloride by means of a " pulverisateur " has found
much favour during the last few years, and the results obtained are
said to be highly satisfactory. No bad effects have followed this
practice in Paris, although 35,000 houses were disinfected in this way
in 1893, and considerably more in 1894. In Berlin this practice is
not recommended, and in India cases of salivation have been attributed
to the use of a mercuric chloride solution as a disinfectant wash for
floor boards.
The Italian Minister of the Intei-ior has recently called the attention
of the railway companies to a clause of the sanitary laws which is as
follows: — "The whole inside of the carriage is to be repeatedly
brushed over with a 2 per mille solution of sublimate. Cattle trucks
are to be thoroughly washed with a solution of carbolic acid, or an
equivalent disinfectant, and with corrosive sublimate when animals
suffering from a contagious disease have been in the trucks." It is to
be noted that mercuric chloride solution, especially if acidified, would
rapidly injure the cushions or hangings. Dr. Thorne, the Medical
■Officer of the British Local Government Board, believes corrosive
sublimate, so far as cholera is concerned, to be its most potent germ-
icide. The official circular issued by Sir G. Buchanan in April,
1888, was confirmed by the Board in 1892. The following method
is recommended : — " Por the purposes of the sick room, such as
reception of soiled handkerchiefs, sheets, and the like, as well as for
the swabbing of floors, a valuable disinfectant solution may be made
with perchloride of mercury. It is well to have this solution slightly
acid, coloured also in such a way that it shall not readily be confused
with drinks or medicines; and proper caution should be given to avoid
accidents in its use. Sanitary authorities will find it advantageous to
have such a solution prepared under the direct instructions of the
medical officer of health, and supplied at a uniform strength at the
infected house by the order of that officer. A solution fitted for the
desired purposes may be made with half an ounce of corrosive sub-
METALLIC SALTS. 139
limate, 1 fluid ounce hydrochloric acid, and 5 grains of commercial
aniline blue, in 3 gallons (a bucketful) of Common water. It ought
not to cost more than threepence the bucketful, and should be further
diluted. The use of non-metallic vessels (wooden or earthenware)
should be enjoined, and articles that have been soaked in it should be
set to soak in common water for some hours before they go to the
wash." The strength of the above solution is 1 in 960 ; it should be
1 ounce of mercuric chloride, or about 1 in 500.
Dr. C. T. Williams, of Brompton Hospital, states that mercuric
•chloride (as well as arsenic, boric, and strong acids) do not interfere
with the tubercle bacillus, but rather promote its growth. Dr.
Whitelegge, on the other hand,* asserts that sulphate of iron and
chloride of zinc are useless, and that the best known disinfectant
is mercuric chloride. Ratinioff t gives a table of comparative values
of disinfectants, and cites experiments showing that amounts of mer-
curic chloride from 1 in 13,300 to 1 in 800,000 killed, in his experi-
ments, various infective organisms, which results are at variance with
those of other observers. Dr. A. Ivert in 1889 treated forty-five cases
of Asiatic cholera in Tonquin with mercuric chloride internally, in
doses of '02 to '04 gramme per twenty-four hours. The death-rate
among these was 20 per cent., whereas the general death-rate was not
less than 66 per cent. He also tried it as a prophylactic agent, and in
no case did any signs of cholera develop. J F. A. Coward § gave mer-
curic chloride (and tinct. ferr. perchlor.) internally in sixty cases of
diphtheria. In some cases he also sprayed the throat with a solu-
tion of mercuric chloride, glycerine, and potassic chlorate. All were
successful, even without the spray.
Solutions of the strength of 1 in 1,000 to 1 in 10,000 have been
for many years used as antiseptic di-essings by surgeons and by
dentists. If strong, the mercury will be absorbed, causing salivation,
and local irritation may also be produced. The formation of an in-
soluble mercuric "albuminate" with the serum exuding from a wound
is apt to throw the mercury out of action. In Laplace's solution this
is prevented by adding tartaric acid to the liquid (see p. 138); but
Drs. Lubbert and Schneider found that the acid caused irritation to
wounds, therefore they use a solution containing mercuric chloride
2 parts, sodium chloride 100, distilled water 600, glycerine 100,
rectified spirits 200, to prevent the albuminate precipitating. || Dr.
Wilson's solution is 1 of mercuric chloride, 1 of ammonium chloride,
and 1,000 of water.H The "St. Bede Disinfectant," made at New-
* Lancet, 1887, p. 76. t Jiied. Centralblatt, vol. xiv., p. 360.
X Comptea Rendus, vol. cvii., p. 695. § Brit. Med. Journ., 1891.
II Chem. and Drug., 1893. IT Pharin. Journ., 1891, p. 960.
140 DISINFECTION AND DISINFECTANTS.
castle-on-Tyne, consists chiefly of sojlium sulphate, mercuric chloride,
and a little sulphuric acid, formed into blocks with indigo, eucalyptus,
and thymol.*
M. Balme has invented an antiseptic paper in the shape of perfor-
ated sheets like postage stamps, made into a book. A white unsized
paper is employed, as it is found not to reduce the mercury and lose
strength as gauze does. In the manufacture, on to each sheet is
dropped from a pipette a known quantity of a standard sublimate
.solution. When dry they each contain an exactly known amount of
the agent, and only require to be moistened and applied to the wound. t
" Sublimate gauze," as used in the German Army, contains about
1 iu 200 or 300 of HgCl2, and is coloured pink by magenta to dis-
tinguish it. " Sal alerabroth '' (ammonio-mercuric chloride) gauze is
also made coloured with aniline blue.
It has been mentioned that it is better to employ distilled water
for making up sublimate solutions, as the carbonate of lime in ordinary
water causes a precipitate. As distilled water may sometimes, as in
war, be unattainable, the difficulty can be avoided by adding an acid,
as in the English and French prescriptions. As an alternative an
alkaline chloride may be added; ordinary salt is generally chosen
for this purpose. Victor Meyer considers the addition of salt and
the use of distilled Avater to be unnecessary, since he found that a 1
per 1,000 solution of mercuric chloride made even with a bad pond
water kept well in the dark for two months.!
C. J. Bond§ recommends a pellet containing 4| grains of mercuric
chloride and 4J of sodium chloride which can be dissolved in a pint of
water in about three minutes, forming a solution of 1 in 2,000. Solu-
tions made with salt do not turn milky with hard water like those
with ammonium chloride.
Vignonjl points out that as a definite strength is of the utmost im-
portance, the permanence of the liquids must be secured. He noticed
that a 1 per mille solution of mercuric chloride in pure distilled water
becomes slightly turbid in from twenty-four hours to two or three
days, and gradually gives a white precipitate. He obtained the
following results : —
Mercuric chloride per litre
(in solution).
Original solution, . I'OOgranirae.
Open to air for 7 days (volume reduced by
evaporation from 500 to 385 c.c, and,
therefore, solutions became stronger), . 0'57 ,,
In a closed riask for 7 days, .... 097 ,,
In a closed flask for 220 days 0*67 ,.
* Lancet, vol. ii., 1889, p. 701. t C/tem. and Drug., 1889, p. 119.
::: Ber., vol. xx., p. 2,970 (1888). § Chtm. and Drug., Aug. 9, 1890.
II C. i?., 1893, Dec. 4.
METALLIC SALTS. 141
Colouring matters diminish the loss, indigo being better than
fuchsine (because the former is acid), but still there is a loss under
the best circumstances from 1 -00 to 0-98 in 7, and to 080 in 220 days.
The alkaline chlorides generally help the keeping power. Solutions
with 10 grammes of sodium, ammonium, or potassium chloride to 1
gramme of mercuric chloride, keep practically unaltered for a very
long time. 1 per 1,000 of hydrochloric acid acts in the same way,
and would be as useful in those cases in which its irritant effect was
not objectionable.
It is evident that the weakening is due to dissociation, a basic
chloride precipitating and an acid remaining in solution. Exposure
and heating cause the hydrochloric acid to be volatilised. The double
salts are more stable, therefore 1 per cent, of salt, or 10 per cent, of
hydrochloric acid, should be added in making up the solution. The
sublimate dissolves more readily when it is finely powdered and well
agitated with the liquid, as it is sparingly soluble and rapidly settles.
Mercury Albuminate, the white flocculent precipitate given on mixing
mercuric chloride with dilute albumen, is non-putrescent, insoluble in
water, but soluble (while moist) in sodium chloride, and in excess of
albumen, thei'efore in blood, serum, «fec. Gauze impregnated with it
is a slow, but mild and effective mercurial antiseptic*
Mercuric Iodide, Hglo, made by precipitating a mercuric salt by
potassium iodide, is scarlet, insoluble in water, but easily soluble in
excess of potassium iodide, to form a double salt, potassio-mercuric
iodide. This has lately come into use as a disinfectant, being said to
have "double the bactericidal power of corrosive sublimate, while
it is less poisonous." It was first suggested by Dr. Bernardy, of
Philadelphia,! and has been patented in France and England by
Collin and Benoist.:J: They use 1 part of mercuric iodide to 1 part of
potassium iodide. "5 to 15*5 grains are added to a litre of the animal
or vegetable liquid to be preserved. Solids are treated with a solution
of 15'5 grains per litre (1 in 1,000) for twelve to twenty-four hours,
when the germs are all destroyed." They also mention mixing it
with eucalyptus and other substances. It is asserted that a solution
of this compound of 1 in 4,000 is equivalent to 1 in 2,000 of mercuric
chloride. " For washing floors a solution of 1 in 4,000 should be
employed, for disinfecting the hands 1 in 2,000, and for instruments
1 in 2 to 3,000.§ Steel instruments would be attacked unless im-
mediately rinsed.
The solid compound is manufactured under the name of " Iodic
* Schneider, Pharm. Centralhlatt, 1888, p. 141.
t BrU. Med. Journ., 1887, p. 789. t Patents, Nos. 15,766 and 16.935, 1887.
§ BrU. Med. Journ., 1887, p. 789.
142 DISINFECTION AND DISINFECTANTS.
Hydrarg.," and is stated to dissolve without decomposition in an equal
weight of water. It is recommended by Waschejewsck for ophthalmia
in a strength of 1 in 5,000. " It does not precipitate albumen
nor cause irritation, and can even be given internally in doses of a
quarter grain." It has also been compressed into tablets of definite
weight. One soloid of "Hydrarg. Perchlor." in a pint of water gives
a solution of 1 in 1,000. Two of "Iodic Hydrarg." in the same
quantity gives a strength of 1 in 4,000.
P. K. Bolshesolsky* strongly recommends a 1 in 10,000 solution of
this salt as an antiseptic in obstetrical and surgical practice.
Thomson proposes as an antiseptic, 1 to 3 of mercuric iodide and
1 to 3 of potassium iodide to 100 of soap. The solution for use contains
1 of mercuric iodide in 4,000 of water. Dr. Woodhead has experimented
on it with favoui'able results.!
Mercuric Cyanide, Hg(0N)2, is sparingly soluble in water, slightly
acid, and inodorous. The basic or oxy-cyanide is similar, but slightly
alkaline. Both are antiseptic and very poisonous. Solutions of the
latter, 1 in 15,000 strength, do not seriously injure instruments, only
slightly precipitate albumen, and are tolerated by wounds and by the
mucous membrane. Chibret:}: found when he added it to peptonised
broth that it had six times the antiseptic power of the chloride, although
it does not act so powerfully on Micrococcus aureus. It has also been
found of service in cases of diphtheria.
Stellden§ reports on 1,400 cases of diphtheria treated with this
remedy, when only 5 per cent, of deaths occurred, as compared with
the ordinary 92 per cent, in that district at the time. (Honey, 450 ;
tinct. aconite, 30 ; Hg(CN)2, 0-3 grain ; also a gargle of 1 Hg(CN)2 in
10,000 of Aq-menth. pip.). Frequent doses and applications were said
to suppress the bacillus.
Zinc Mercuric Cyanide. — Sir Joseph Lister introduced this compound
in 1889. To a solution of potassio-mercuric cyanide a zinc salt is
added ; the bulky white precipitate is washed with water till the
washings are almost free from mercury, then drained, triturated with
starch, ground with potassium sulphate to aid the pulverisation, and
carefully dried. To fix it on gauze, 3 to 5 per cent, of it is suspended
in a 1 in 4,000 solution of mercuric chloride, and the gauze dipped
with agitation. The powder keeps when dry, but the gauze must be
prepared when required, and used moist.
B. Dotty cast some doubts on the definiteness of this compound,
* Proc. Arkhangelsk Med. Soc, 1S94, vol. ii., p. 191.
t Brit. Medical Association, Edinburgh Meeting, 1888.
t Compt. Rend., vol. cvii., p. 119. § Merck's Bull., vol. i., pp. 28-40.
II Lancet, vol. ii., 1889, p. 1133.
METALLIC SALTS. 14S
questioning the presence of mercury in any quantity. Dunstan*
proved that the original precipitate, which he prepared by a variety
of methods, was a true double salt of the formula Zn^Hg(CN)j^ or
HgCNo, 4Zn(CN),, but that it was decomposed in the washing,
the soluble Hg(CN)2 being removed, and the insoluble Zn(CN)2
remaining, so that the result was a mixture of variable composition
consisting mainly of zinc cyanide, with, in different samples, 6, 8-5,
10, and 18 per cent, of Hg(CN)o — that is, about a ^ to ^ of what
it should be. Long washing or hot washing removes all the mercury.
However useful in practice this preparation may prove to be,
the variation in its composition militates against uniform results.
Dunstan tried to prepare it in alcohol and other ways, but without-
success.
Mercuric Chloro-amide, HgNHgOl, is the soluble white powder
well known as "white precipitate." It is much used for killing
Pediculi, and is a mild intestinal antiseptic.
The following organic mercurial compounds are all antiseptic and
have varying disinfectant powers. All are poisonous. They are-
occasionally used in emulsified lotions or injections, or in ointments-
and gauze, against syphilis : —
Carbolate, (CgH50)oHg (Szadek), Sulphocarbolate, and Benzoate-
{StuTcowenkow) are white powders, almost insoluble in water.
Salicylate {Silva-Araujo and Szadek) in pills, -^-^ to | grain, and as-
an injection in 0*4 per thousand solution for gonorrhoea and syphilis,
has perhaps been more widely used than any other of the newer
compounds of mercury.
Thymolate (CjoHj3 0)Hg.HgN03, Thymolacetate, and Thymosul-
phate, yV to \ grain in pills, were recommended by Kobert for
syphilis.
Tannate, greenish-brown insoluble scales ; 1 to 2 grains have been
recommended as an antisyphilitic by Lustgai-ten.
Imidosuccinate, (C2H4(C02)2N)2Hg, is soluble in 25 parts of water.
4 grain is used hypodermically in syphilis (Fbw Mering and VoUert^
1888).
Naptholate and Naptholacetate are condemned by laddosohn and
Zeissing as producing pain.
Peptonate and " Glutino-peptone sublimate," made by acting on
gelatine with hydrochloric acid and adding 25 per cent, of mercuric
chloride, are met with in 1 per cent, solution for injections, and are
said to be almost painless and to be rapid and efficient (Dr. Hufer),
The doses are about equal to \ grain of mercuric chloride.
Any surfaces washed with a mercury salt will soon be blackened
* Chcm. Soc. Jcnrn., 1892, p. C66.
144 DISINFECTION AND DISINFECTANTS.
■vrith sulphuretted hydrogen. Organic matter is liable to reduce and
throw the mercury out of action. The mercuric solutions are com-
patible with i)ero.\ide of hydrogen, acids, permanganate, zinc and
copper salts, glycerine, phenol, and most aromatic compounds, but
not with borates, sulphates, phosphates, carbonates, or alkalies, which
precipitate them.
COMPOUNDS OF VARIOUS METALS.
Tin. — stannous Chloride (protochloride of tin), SnClg, has been sug-
gested as a disinfectant.* It is comparatively safe, and does not
corrode lead pipes. A solution containing 1 per cent, kills spores
after an exposure of two hours. When kept for use it should be
mixed with an equal quantity of ammonium chloride, which prevents
the formation of the insoluble oxychloride of tin.
It is difficult to see any advantage in its introduction, as its bacteri-
cidal powers are feeble, and chiefly due to its hydrochloric acid. It would
absorb ammonia and sulphuretted hydrogen, like many other agents.
Bismuth. — Gayon and Dupetit f were the first to point out that
salts of bismuth, even in small quantities, completely prevented the
secondary fermentations which take place in worts, but they have not
been used to any large extent.
Bismuth subgallate, C-H-O^-Bi, formed by the action of bismuth
nitrate on gallic acid, is soluble in water, alcohol, and ether, has lately
been introduced under the name of " Dermatol." F. Rohrer | says
of it, "This new disinfectant in the different forms of purulent in-
flammation of the outer and middle ear, also in affections of the nose,
has lately claimed to be a great success. A bacteriological test, in
which dermatol mixed with broth or gelatine was infected with
anthrax, has revealed, however, that it is not a germicide, and does
not even retard the growth. In fact, the bacillus actually changes the
dermatol, which becomes yellow, and finally black. The same dis-
coloration occurs in the ear." So that it simply acts as an astringent.
Colosanti and Dutto, on the other hand, report favourably on its use
.as an internal disinfectant.
The salts of other metals have not been used to any large extent.
iVIiquel classes Silver Nitrate as equal to mercuric chloride.
Osmic Acid is a very powerful bactericide, as mentioned by Klein
•and supported by Koch. Koch says that Silver and Gold compounds
are all inhibitory on tubercle, especially Gold Cyanide, Au(CN)3, dis-
solved in potassium cyanide ; 1 part Au(CN)3 in 2,000,000 parts of
solvent checking the growth of tubercle bacillus.
• Year-Book of Pharmacy, 1887. t Comp. Rend., vol. ciii., p. 883.
i Centr.f. Bacteriol, 1S92, vol. xii., p. 625.
METALLIC SALTS. 145
With reference to compounds generally, in view of the search for
new disinfectants, it may be mentioned that —
1. As free acids, even the weakest, such as acetic and carbonic,
retard, as a rule, the growth of bacteria, which usually require a
slightly alkaline medium, the acid salts and those of the metals which
have an acid reaction retard putrefaction by virtue of their acid con-
stituent, and independently of the nature of the metal.
2. Some metallic salts precipitate albumen — e.g., those of mercury,
copper, and most of the heavy metals. Such, by coagulating protoplasm,
must kill the organisms, if they can penetrate deep enough. With
these salts, disinfection is, therefore, a condition of quantity and time.
3. These metallic salts, and some other substances, such as lime,
alumina, phosphates, and charcoal, may starve bacteria by withdraw-
ing, or rendering insoluble, their food.
4. The borates, aroniatic substances generally, and a few other com-
pounds exert a direct toxic influence on organisms which, as far as
known, is physiological and not chemical. Given sufficient quantity
and time, they may actually kill the bacteria and so act as real dis-
infectants, but they usually only retard the growth, and therefore are
chiefly used as antiseptics. It is possible that some of them may
form loose compouilds with protoplasm which interfere with its vital
functions.
5. Reducing agents, such as sulphites and ferrous salts, withdraw
oxygen, which element is necessary for the growth of most organisms.
6. Oxidising agents, like ozone, peroxide of hydrogen, the halogens,
and permanganate, act on bacteria by destroying their food, poisoning
them, and finally completely destroying them. These are the only
perfect disinfectants, yielding the ideal condition of sterility, nothing
to grow, and nothing to feed on. It remains solely to find the
minimum required, and then to use a little more for safety. All
other disinfection must be unsatisfactory, and only means suspension
for a time.
7. A few easily reducible metallic salts are fed oh by the organisms,
which assimilate one of the elements, to be deposited in their tissues
as coloured granules distinctly visible under the microscope. Silver,
gold, and some iodine compounds are examples. After a time this
deposition chokes, and finally kills them. Probably this accounts for
the fact so often observed, that very minute percentages of many
poisons actually promote the growth of organisms, which larger
amounts destroy. Ordinary therapeutics furnish many parallel in-
stances.* Richet remarks f that, although very small quantities of
• Note Crace-Cal vert's observation under Mercury, p. 136 ; Dr. Williams, ibid.,
p. 139. t Comptes Rendus, 1892, p. 1494.
10
146 DISINFECTION AND DISINFECTANTS.
certain metallic salts retard or wholly prevent the development of the
lactic ferment in milk, still smaller^ quantities even act as accelerators
of the fermentative action.
This explains the absolute necessity of working quantitatively in
disinfection, and also many of the discrepancies and misstatements
which exist in the literature of the subject.
Richet also observes * that the ferment appeared indifferent to salts
of copper and mercury in quantities inferior to "00025 gramme per
litre; in doses of '0005 gramme per litre these salts possessed an
accelerative action, and in quantities of 0-001 per litre their antiseptic-
properties first became evident. The toxic action of the metallic
poison does not appear to affect the chemical activity of the ferment^
but rather its powers of multiplication. The biological relations as-
regards the toxicity of metals do not follow chemical laws, as certain
metals which are chemically very similar have a very different toxicity,
and it is especially noteworthy that the rarer metals, to which the
ferment is pi'obably not so well accustomed, appear more toxic than
the common metals. The prohibitive dose of zinc is 1 gramme, whilst
0"15 gramme of cadmium sulphate completely prevents fermentation.
Ferric and manganese salts are also less toxic than cobalt and nickel
salts.
While calcium salts are constituents of food, barium, chemically the
next metal, gives compounds that are poisonous. Among the rarer
metals may still be found a stronger antiseptic than any yet examined.
It would appear that in a series of similar metals the higher the atomic
weight the more toxic the salts. In the case of the non-metals the
reverse may be the case, but at present there is want of data for
ascertaining how far the periodic law of the elements bears on their
antiseptic and disinfectant action.
* Loc. cit.
ORGANIC SUBSTANCES. 147
CHAPTER VIII.
ORGANIC SUBSTANCES.
Coal Tau and its Products : General Account— Tar Water. Hydrocarbons
(Neutral Tar Oils) : Benzene — Toluene — Naphthalene — Anthracene — Naph-
thalene Urinal Cakes — "Lauraline." Petroleum. Phenols. Phenol or
Carbolic Acid : " Properties " — Variation in the Commercial Strength — The
" Victoria Carbolic Acid Powder"— Carbolic Fumigation — Antiseptic Power
of Phenol — Not a Disinfectant — Uses and Dangers— Objections to the employ-
ment of Phenol — Prescriptions in Different Countries. Carbolic Powders :
M'Dougall's — Calvert's — Mayor's — Phenolith — Other Patents. Surgical
Preparations : Carbolised Oil — Gauze— Carbolic Wool — Danger of Phenol
in Surgery — Carbolic Soaps — Tooth Powders — Various Preparations — The
cost of Phenol. Halogen Compounds of Phenol : Tribromophenol — lodo-
phenols. Sulphonic Derivatives: " Sulphocarbolates " — Sozo-iodol — Aseptol
— Sozol— Benzene-sulphonic Acid — Phenyl substituted Patty Acids. Cresol
AND ITS Higher Homologues : Table of the Phenol Series — Sources —
Creosote Oil— Ufees of Creosote Antiseptic Powder — "Bacillite " — Lysol — Ex-
periments on its Efficiency — Pixol — Pixene — Question of Solubility — Tricresol
— Jeyes' Disinfectant and Creolin — Creolin Baths — Smith's Carbolated
Fluid— Artmann's Creolin — Strathclyde Disinfectant — Essets' Fluid. Saprol :
Its Peculiar Properties — Allen's Fluid — Production of Ozone. Izal: Euro-
phene — Resorcinol — Pyrocatechol — Pyrogallol. Wood-Tar Derivatives i
Products of Destructive Distillation of Wood — Stockholm Tar — Retinol —
Resol — Fatal to Plants. Wood Creosote : Uses and Antiseptic Power.
Guaiacol : Medicinal Uses — Guaiacol Carboxylate — Creosol — Kresyline —
Little's Soluble Phenyle. Naphthalene and Naphtiiol : Naphthalene
— Naphthalene-Sulphonic Acids — Naphthols — Beta-naphthol — Its Value in
Internal Antisepsis — Betol " Microcidine " — Alumnol— Hydronaphthol — Its.
Use in Gauze — Oxynaphthoic Acid,
TAR AND ITS PRODUCTS.
It has long been known that the varieties of tar have antiseptic and
preservative properties ; hence the use of coal tar for coating wood,
and of wood tar for ropes and sacking. Coal tar consists for the most
part of a mixture of " aromatic " compounds derived from the hydro-
carbon benzene, OgHg. They are more or less volatile ; many have
offensive odours, and act as narcotic poisons. This poisonous action
may render them disinfectant when used in sufficiently large quantities.
Some coagulate albumen, and are caustic, like phenol. A few are
soluble in water, and these are the most powerful physiologically. As
far back as 1753 Bishop Berkeley extolled the virtues of tar water for
148 DISINFECTION AND DISINFECTANTS.
nearly every ailment ; but its use is now replaced by more definite
preparations.
By treatment with acid and alkaline solutions in succession, the
tars are separated into three groups of bodies : —
I. Hydrocarbons, such as benzene, toluene, xylene, naphthalene,
anthracene, &c. These are neutral bodies, insoluble in water, alkalies,
and acids; Most of them, however, can be dissolved, or at least
emulsified, by heating with a strong solution of ordinary or resin soap,
with or without the addition of alcohol or wood spirit. The dark-
brown clear syrup turns white and milky with water, the hydrocarbons
being precipitated in minute oily globules, which slowly rise as a scum
to the surface, leaving a strongly alkaline solution in the soaps. All
these mixtures smell of tar, and are in different degrees antiseptic,
but less so than the phenols. They are known in commerce as
■" neutral tar oils." Specifications for disinfecting powders generally
demand their absence, and in fact they are looked upon usually as a
detriment, or even as an adulteration, if present in any quantity in
disinfectants. The hydrocarbon benzene, CgHg, and its higher homo-
logues toluene, C-Hg, tie, have no antiseptic value. The dei-ivatives
of thiophene (a compound usually present in crude benzene), C^H^S,
have been used for skin diseases.*
Naphthalene, C^gHg, and anthracene, Cj^Hjq, when pure are white
crystalline solids of greasy feel and tarry odour, slowly volatile, in-
soluble in water, and feebly antiseptic. Naphthalene is used as an
insecticide, and is sometimes employed locally in scabies as a 10 to 20
per cent, solution in oil. It is to be avoided in cases where large
surfaces are exposed, but has been used internallyf and as an antiseptic
for wounds. + Its derivatives will be further considered (p. 177).
Naphthalene is at present much used as the basis of cakes or blocks
sold very cheaply as "disinfectants" to hang up over sinks and in
closets, and to place in the basins of urinals. Some are said to contain
"camphor and eucalyptus." The urinal blocks certainly prevent the
urinous smell, partly by masking it and partly by retarding the
ammoniacal fermentation, but they are of no use as disinfectants.
There is a recent patent § for naphthalene tablets.
" Lauraline " contains camphor and carbolic acid with much naph-
thalene. ||
Petroleum may here be incidentally mentioned, although it consists
mainly of the paraffin series of hydrocarbons, chiefly liexane, CgHj^.
It has long been used as an insecticide in horticulture.
* Repertoire de Pharm., 1892, p. 157. i Amer. Jourv. of Pharm., 1834, p. 645.
t Squire's Companion, 1890, p. 289. § No. 5,036, 1892.
li Chem. and Drug., Sept. 3, 1892.
ORGANIC SUBSTANCES. 149
II. Phenols or so-called "tar acids," carbolic, cresylic, &c. They are
hydroxy-derivatives of the aromatic hydrocarbons, and combine with
caustic alkalies to form carbolates, «tc., soluble in water, from which
acids again liberate the phenol. The series include phenol, cresol, and
liigher homologues ; the latter are present in the fractions of higher
boiling point, and form unstable compounds with alkalies which are
even decomposed by water ; hence their solutions turn milky on
dilution. They are the subject of a large number of proprietary
preparations, and will be described further under phenol, cresol, &c.
III. Basic substances are extracted from coal tar by treatment with
acids. They include aniline, pyridine, quinoline, ifec. They are mostly
soluble in water, and are discussed more fully in a later section
(p. 184).
PHENOL OR CARBOLIC ACID.
Phenol, C^'ilr^(0'H.), is the simplest member of the group of phenols
or hydroxy-benzene derivatives, and is commercially known as carbolic
acid. The phenols all contain hydroxyl united to the "aromatic"
nucleus or benzene ring of carbon atoms, and are more or less anti-
septic. Most of them coagulate albumen, and are therefore styptic ;
they are poisonous in different degrees, and thus, if in sufficient quan-
tity, may be true disinfectants. They are mostly of sparing solubility
in water, which militates against their general use; they easily dissolve
in alkalies and alkaline earths, forming substitution compounds usually
called carbolates. These compounds are alkaline, odorous, and some-
what caustic ; acids, even carbonic, render their solutions turbid,
separating the phenols as an oily layer if the solution is moderately
concentrated. Such substances, made with lime or magnesia, constitute
a number of the "disinfecting powders," which slowly give off the
phenols on exposure to air, leaving behind the inert carbonates of
lime and magnesia. The earthy bases then only act as a vehicle, and
any undue excess of them must be considered as an adulteration.
The pure compounds are not used, as they are deliquescent, caustic,
and too rapidly soluble. The powders are usually valued and sold as
containing a stated percentage of the phenol, «kc. Many so-called
disinfecting powders now in the market are supposed to contain 15 per
cent, of phenol, when in reality they possess only a trace. "A 15 per
cent, carbolic acid disinfectant powder, free from tar oils and sulphur-
etted hydrogen " {i.e., not made from gas-lime), is a common form of
speciBcation for this class of disinfectant.
A striking example of the absolute necessity for carefully examining
all such powders before use is furnished by the recent exposure of the
" Victoria Carbolic Disinfectant Powder." Dr. Barwise found in an
150 DISINFECTION AND DISINFECTANTS.
epidemic of typhoid at South Wingfield in 1892 that " excreta well
mixed with the powder and buried " polluted the drainage, so that the
infection was carried to a large number of people lower down the hill.
Although the powder was stated to contain 15 per cent, of carbolic
acid, an analysis showed that it had barely any odour of carbolic acid
and only the merest trace of tar oil, and there was no weighable quan-
tity of carbolic acid. Moreover, even the best powders deteriorate on
exposure to air, and may become inert. Phenol itself is prepared from
tar distillates, and in the crude state is a dark oily liquid containing
also the higher homologues, cresol, xylol, cumol, and cymol, besides
neutral tar oils of less disinfecting power. "Synthetic" carbolic acid
(made from benzene), and free from cresol, (kc, has been sold, but its
price is somewhat prohibitive. Pure phenol forms colourless crystals,
turning red in the light. It melts at 41° C. and boils at 181-5° C,
and therefore is not easily volatile. It can be volatilised more rapidly
by melting and then dropping on to a heated shovel — not too hot, or
it is liable to catch fire {Calvert). The vapour is apt to cause severe
headache, giddiness, and nausea. A small quantity of water liquefies
the crystals, forming a hydrate, which, however, when added to more
water, only dissolves to the extent of 1 in 15, the rest generally at first
floating as an oily layer, although it is slightly heavier than water
(specific gravity, 1*065). Hence it must be made into a solution for
use by mixing with excess of water and agitating until dissolved.
It is certainly antiseptic ; but as to its disinfecting power, opinions
are very diverse. M'Dougall and Calvert extolled it above other
disinfectants ; but the latter observer, though he states that 1 in 200
prevented the putrefaction of beef juice for six days, yet acknowledges
that when added in that proportion to already putrid beef juice or egg
albumen, it had no efiect on the organisms present. The vapour also
produced no effect during twenty-four hours on vaccine lymph.
Miquel asserts that the vapour of phenol " after fifteen or twenty
days of action at 20° C. is absolutely incapable of destroying the vitality
of bacteria," and that 3-2 grammes of phenol is required to prevent
growth in a litre of beef tea.*
Pasteur and Lister have strongly advocated its use in surgery where
antiseptic action is mainly aimed at. Phenol was extensively tried by
Orookes under the sanction of the Cattle Plague Commission. His
report estimated its value in destroying the infectious matter as very
high (1867).
Koch remarks! that "carbolic acid also kills if of considerable
strength and acting for a long period." He also observed that solu-
* Les Organismes, 1883, p. 290.
t Mitiheil. a. d. K. Gesund., 1881, vol i., p. 234.
ORGANIC SUBSTANCES. 161
tions of carbolic acid in oil do not possess the same disinfecting power
as those in water. This is important, in view of the frequent use of
oarbolised oil in surgery.
When disinfection is required to be completed in less than twenty-
four hours, which is generally the case, Wolffhiigel and Von Knorre
find carbolic acid useless.*
In Koch's later experiments, silk threads with anthrax spores were
placed in cai'bolic solution of various strengths. A 5 per cent, solution
killed the spores in two days, whilst sporeless bacteria, as those from
fresh blood, were killed by 1 per cent, solution, but not by ^ per cent,
solution, as proved by inoculation. " For safety the strength should
be 5 per cent, or even more to kill in twenty-four hours." "As an
antiseptic, phenol solution 1 in 850 entirely prevented the development
of anthrax spores, 1 in 1,250 caused marked hindrance. Other bac-
teria are less affected. The vapour at ordinary temperatures, even
when allowed to act for six weeks, had not the slightest effect on
spores, but at 55° C. many were destroyed in half an hour. After
three hours there was very little germinating powei', after five or six
all were killed. Other disinfectants act similarly at high tempera-
tures." t (See p. 139 for Ratinoff's comparison of phenol with mercuric
chloride, &c. His effective strength is 1 in 400.)
Klein observes that phenol (1 in 400 or 500) in nutrient solutions
has a decided restraining power, but he emphasises the fact that the
spores are only " stunned," not killed ; for, if removed and inoculated
into an animal, they recover and rapidly cause death. He continues,
" as is obvious, according to the nature of the bacillus, the strength of
the solution, and the time of action, the result varies. For instance,
mature B. anthracis is killed by 5 per cent, phenol in five minutes, but
is not injured by 1 per cent, in five minutes."
Crookshank obtained favourable results on the tubercle bacillus.
Patients whose lungs were tuberculous have been benefited by inhala-
tions of carbolic vapour. %
As to the typhoid bacillus, it is so resistant to phenol that the
isolation of this organism is effected by growing in a carbolised culture
which kills other germs, but has no action on it.§ It is grown in
tubes of gelatine by adding to each 10 c.c. of the nutrient medium,
4 or 5 drops of 1 in 20 per cent, phenol. Cassedebat at Marseilles
found that several other organisms offered quite as much resistance to
phenol as the typhoid bacillus itself || Yet Dr. Cameron recommends
* Journ. Soc. Chem. Ind., June 29, 1882.
+ Mittheil. a. d. K. Gesund., Dec. 3, 1881. t Bacteriology, 1887, p. 151.
§ Chautemesse and Widal, Oaz. Hebdomadaire, 1887, p. 146.
II Ann. Inst. Pasteur, Oct. 25, 1890.
152 DISINFECTION AND DISINFECTANTS.
a 5 per cent, solution of carbolic acid for the " decomposition " of
typhoid stools;* and even more recently Dr. Gover, in his report to
the Director-General of Prisons, asserts that " Carbolic acid is the
most certain and powerful of the numerous substances \ised as anti-
septics and disinfectants."
The value of phenol may be summed up as follows : —
1. In a strength of 1 in 400 it is a powerful antiseptic, restraining
ptitrefaction when started, and preventing it for a long time when not
commenced, but in this respect it is far inferior to mercuric chloride.
2. To actually kill bacteria it requires the high strength of 1 in
20, and even this has not a certain action with all organisms, nor
does it kill the spores of such as anthrax. Therefore it is not a
satisfactory disinfectant.
3. It does not absorb sulphuretted hydrogen nor ammonias, hence
it is not a deodorant.
4. Its persistent odour is a decided disadvantage, as the smell
remains even when the quantity is utterly insufficient.
5. For treatment of sewage it is a failure, even in proportions
practically impossible. Moreover, it renders the material useless
for manurial purposes. In Japan, after a cholera outbreak in 1882,
the Government instituted some experiments to elucidate this point,
and clearly showed that "a solution of 0*05 gramme of phenol in
100 c.c. of water weakened the germinating power of the seeds, and
with a solution of 0*1 per cent, only one-third of the possible seeds
germinated, and in all cases the acid delayed the process of ger-
mination."
6. In surgery it is of considerable value. Lister has recently
pointed out that it has a powerful affinity for the epidermis, pene-
trating deeply into its substance, and mingling with fatty matter
in any proportion, whereas mercuric chloride required a special
cleaning of the skin, as it could not penetrate in the slightest degree
into anything greasy. It is free from the danger of mercurial
poisoning, but if used too strong it may itself be absorbed and
cause dangerous symptoms. For aseptism (prevention) as against
antiseptism (cure) in surgery it has, therefore, a distinct field of
usefulness.
Carbolic acid is still in high favour with different Governments
and medical associations. Thus the recent suggestions made by
the Society of Medical Officers of Health are as follows : —
1, For the air of sick rooms : sheets are suspended and saturated
with carbolic solution or chloride of lime.
2. For matters passed : ferrous sulphate is added.
* Brit. Med. Journ., 1S90, p. .370.
ORGANIC SUBSTANCES. 153
3. All utensils should be washed in carbolic solution.
4. Linen should be treated with the same.
5. Ambulances and steamers should be cleansed with carbolic
solution.
The solution recommended is a \ pint of carbolic No. 4 (a pure
liquefied acid containing about 90 per cent, phenol) to a gallon of
water.
These recommendations are open to the criticism that : —
1. The prescribed solution which only contains about 2^ per cent,
to 3 per cent, of phenol is only half the strength specified by Koch
and others as capable of killing mature germs, and far below that
required to destroy spores.
2. The odour from a suspended sheet is liable, as before mentioned,
to cause headache and nausea, and it is very improbable that such a
method of application does more than partially disinfect the air, even
if the carbolic solution is a saturated one.
The Commissioners of Inland Revenue in 1892, in an investigation
for the Board of Trade, state in their report, " That nearly every
liquid disinfectant on the list was found to be inferior to an equal
weight of the carbolic acid powder." The Committee decided to adopt
as standards a solution containing SO per cent, of carbolic acid, and a
])owder containing 20 per cent. This is practically Messrs. Calvert's
strength for their liquids No. 4 and 5. Their powder is guaranteed
to contain 15 per cent, of carbolic and cresylic acids.
In the Clerkenwell Vestry district where carbolic acid is distri-
buted free to ratepayers, it is bought on the following specifi-
cation : —
" (1) 95 per cent, of clear carbolic acid fluid, free from tar oils and
sulphuretted hydrogen; (2) 15 per cent, carbolic disinfecting powder,
with same proviso ; (3) 70 per cent, carbolic acid dissolved in caustic
soda, also free from tar oils and sulphuretted hydrogen."
In Russia, carbolic acid seems to be the chief, if not the only, dis-
infectant employed by the officials. In that country the slightly
active 50 per cent, to 60 per cent, crude acid has been officially pre-
scribed, whereas the German law properly orders the use of crude
100 per cent, acid, which consists of the really active phenol unmixed
with valueless tar oils.*
The Berlin administration order solutions of two strengths —
" strong," consisting of 1 part pure phenol to 18 of water ; and
"weak," 1 to 45 parts.f The same regulation points out that
fumigation by means of aromatic substances is of no value in dis-
infection.
* Pharm. Zeitung., Aug., 1892. + Polizei Veronlnung, Feb., 18S7.
164 DISINFECTION AND DISINFECTANTS.
The Belgian Government order 2 or 3 per cent, to be mixed with
excreta, under the same conditions as in this country.
Caibolic Powders. — In many cases the base of the powder consists
of slaked lime, but the " carbolate " of lime, which is formed in this
way, only slowly gives up its phenol. One of the oldest forms is
''M'Dougall's Disinfecting Powder," prepared by adding crude carbolic
acid to impure sulphite of lime obtained by passing sulphurous acid
over ignited limestone. The sulphite of lime in this powder is added
to absorb sulphuretted and phosphuretted hydrogen. It dissolves
readily in water, so that there is no danger of choking drains or
appreciably increasing the quantity of solids in the sewage. For
fumigating purposes the powder is mixed with water in an ordinary
zinc pail, preferably a wooden or earthenware receptacle, adding a
little sulphuric acid. A " sewage carbolic acid " of 25 per cent,
strength has been advocated for use in conjunction with the powder
and with lime, in the proportion of 1 gallon of carbolic acid, 10 lbs. of
disinfecting powder, 10 bushels of lime, and 100 gallons of water.
This mixture is stated to be sufficient for 50,000 gallons of sewage,
which is rendered imputrescible, and all smell is removed. If the
powder contained 15 per cent, carbolic acid, the total amount present
in the sewage would barely amount to 8 parts per million, and this
quantity is totally inadequate for sterilisation,
Allen* gives the following as the composition of a sample of the
base of M'Dougall's powder after extraction of the carbolic acid : —
Silica 2-4
Alumina, 3*4
Ferric oxide, Traces.
Lime, 46"5
Magnesia, . 0*3
SO2, 7-5
SO3, 29-2
CO2 (water and undetermined matter), .... 10"7
1000
Corfield remarks: " Carbolates of lime and magnesia and sulphites,
«uch as M'Dougall's powders, merely assist in delaying decomposition,
but do not prevent it ultimately."
"Calvert's Carbolic Powder" is guaranteed to contain 15 per cent,
©f carbolic and cresylic acids. It is prepared by adding crude carbolic
acid to the residue left from the manufacture of aluminium sulphate
from shale or kaolin. The following is an analysis of the base after
extraction of the phenol : — f
* Commercial Organic Analysis, 1886, vol. xi. t Analyst, 1878.
ORGANIC SUBSTANCES. 155
Silica 67-4
Alumina, 28-0
Ferric oxide Trace.
Lime, 0*8
Undetermined, 3 '8
100
" Mayor's Disinfecting Powder " has also a silicate base and " con-
tains 15 per cent, carbolic acid." The advantage claimed is that "the
action of the acid is entirely free to perform its work of disinfection,
none of it being absorbed and retained by the base."
"Phenolith" contains the phenols and cresols of tar with infusorial
earth (siliceous), sawdust, &c. ; * the patent also includes the use of
mixtures of phenol and boric acid for preserving meats, hides, (kc.
Tweedie t patented a mixture of phenol, turpentine, and camphor
with " any dry vehicle."
The carbolic powders of commerce are generally coloured pink or
brown by aurin or ochre. I
It is now generally admitted that road disinfection by carbolised
lime is of little value, since the volume of air and earth is too great
for any real disinfection to be effected in this way. Local authorities,
however, in many districts generally regard such treatment with
favour.
In surgery the following preparations containing phenol are used : —
Carbolised Solution, 1 or 2 of phenol in 40 of water ; Carbolised Oil,
same strength used as a dressing (Koch states that it has much less
power than the solution); 2 per cent, solution for hypodermic injections
and as spray for erysipelas ;§ 5 per cent, injection for anthrax.|]
Carbolised Gauze (Lister). — Phenol, 1; resin, 4; parajfin, 4; melted
together and the gauze dipped in this mixture. Vaseline is sometimes
added to give pliancy. Absorbent gauze is made with phenol, glycerine,
and dilute alcohol, and is stated to be more powerful than the ordinary
gauze. At the temperature of the body the phenol is slowly given off,
causing an antiseptic vapour to envelop the wound.
Carbolic Wool should contain 5 per cent, phenol. Five commercial
samples analysed were found to contain 1*06, 1'07, 0*69, 0*25, 5 '08 per
cent, respectively, showing that they were either badly prepared or
had lost their strength by careless keeping. Carbolic wool, like all
articles containing volatile medicaments, should be preserved in per-
fectly air-tight vessels.
♦ Holtz, Patent No. 5,193, 1878. t Patent No. 17,042, 1888.
+ Joum. Soc. Chem. Ind., 1889, p. 913.
§ Brit. Med. Joum., 1888, vol. xi., p. 947. II Ibid., p. 601.
156 DISINFECTION AND DISINFECTANTS.
Danger of Phenol in Surgery. — According to Lowe, the effect of the
contact of plienol with any large surface of the lower part of the body
is apt to be fatal, but it has often been applied to the arms with
impunity. Gosselin made a series of experiments bearing mostly on
the action of phenol on the living body, as in surgical operations, using
1 to 5 per cent, solutions in dilute alcohol upon blood circulating
through a membrane, and found that the circulation of the blood
through the capillaries was arrested, in direct proportion to the
strength of the solution. He supposes that the phenol coagulates the
blood like a caustic, first (?) acting as a germicide, then " as a semi-
caustic or astringent."
Carbolic Soaps are made in great variety. They should contain
about 8 per cent, or more of phenol, but many contain not more than
1 per cent. Woodhead* and Cameron f have pronounced against their
use. They are largely used in washing, and contain tar oils, naphtha-
lene, ttc, with varying amounts of phenol. Their value is more than
doubtful as disinfectants, though they certainly are potent against
insects.
Carbolic tooth powders are also made. They are antiseptic, but are
not very pleasant.
A few other preparations remain to be mentioned. There are a
large number of patents for mixing " phenoloids," containing more or
less carbolic acid, with peat fibre, ground blast-furnace slag, cinders,
sawdust, and other inert absorbents. They present no special advan-
tage.
" Disinfectol " is an oily blackish liquid containing resinous soaps,
soda, and compounds of phenol dissolved in hydrocarbons introduced
into commerce by Loewenstein. It mixes readily with water, forming
an emulsion. Several preparations of this type, tar products dissolved
in alkalies, will be described under Cresol.
" Eademann's patent " is pure phenol melted on a water bath,
cooled quickly and stirred. The small crystals that separate are
mixed with 10 per cent, of pure boric acid and pressed into cakes.
He claims that this form is not injurious to the skin. I
An "Aromatic Carbolic Liquid," much used in Russia, is a tincture
of phosphorised phenol with musk, oil of wintergreen, &c.§
Phenol has been used internally in capsules and solutions to arrest
fermentation, b\it opinions as to its value are conflicting. Betol has
been found far preferable for this purpose {q.v.).
* Brit. Medical Assoc, Edinburgh Meeting, 1888 ; see under Hgl2, p. 142.
t Sanitary Record, 1890. t Joum. Soc. Chem. Ind., 1889, p. 131.
§ See Chemist and Druggist, 1888, p. 32 ; A. H. Allen, in the Brit, and Colonial
Druggist, 1887. p. 364 ; and Journ. Soc. Chem. Ind., 1887, p. 761.
ORGANIC SUBSTAN'CKS. 157
Vallin points out* that using 1 litre per day of a 5 per cent,
solution of phenol for adding to excreta, Jrc, 50 grammes of phenol,
or nearly 2 ounces, would be required daily for each patient This
would be a large item of expense in a hospital, and even in those
devoted to infectious cases, the consumption of carbolic acid is seldom
a fraction of this quantity.
HALOGEN DERIVATIVES OF PHENOLS.
The substitution in phenol of one or more of the hydrogen atoms
by chlorine, bromine, or iodine can be easily effected by the action of
these elements in the presence of water. Such substitution seems to
increase the antiseptic power, but at the same time it causes the
compounds to become much more unpleasant in odour, diminishes
their solubility, and makes them more corrosive and very irritating
to the eyes.
Parachlorophenol, C,;H^0HC1, is a crystalline body, m.p. 33° C,
soluble in sj)irit, ether, and fixed oils, and practically insoluble in
water. It has been used as an ointment (2 to 3 per cent, with
vaseline) in the treatment of erysipelas and lupus.
A. Spengler also uses a 2 per cent, solution as an effective dis-
infectant for the sputa of phthisical patients.f
Hargreaves J manufactures " cblorophenols by the action of chlorine
or hypochlorites on carbolic acid, tar, «kc., mixed with absorbents to
form a disinfectant."
Tribromophenol, C^iH.^BrgOH, is a white or brownish crystalline
volatile substance, very insoluble in water, obtained by adding
bromine water to phenol solution, when it falls as a white precipi-
tate. It is interesting as a delicate test for phenol, and as a way of
separating it from cresol, since tribromocresol is liquid. Both com-
pounds have disagreeable odours, and are antiseptic, but too insoluble
to be of much use.
lodophenols are similar, but very unstable, being easily decomposed
by light. Experiments with these comi)Ounds generally have not been
favourable.
SULPHONIC DERIVATIVES.
Concentrated sulphuric acid acts on almost all the phenols, forming
compounds soluble in water, and yielding soluble and crystallisable
salts which are usually inodorous. In most cases two or more isomeric
acids are formed, differing in characters. "When phenol is so heated,
the ortho- and para-acids are formed. Their solubility, absence of
* Disinfectants, p. .335. t Sem. Med., Oct. 31, 1894.
:: Patent No. 18,460, 1889.
158 DISINFECTION AND DISINFECTANTS.
odour, and the comparative harmlessness of the salts, have directed
much attention to them as antiseptics. Their formation may be
typified by the following equation —
CeHjOH + S02<,gg = H2O + S02<^^«g^^
The salts in commerce were formerly called sulphocarbolates,
or phenyl-sulphates. The sodium and zinc salts are in the British
Pharmacopoeia. They easily crystallise and are inodorous.
Sodium Paraphenol Sulphonate (" Sulphocarbolate") is a mild
antiseptic, and is used in medicine for "disinfecting the intestinal
tract." It is probably broken up in the body into phenol and
acid sodium sulphate, each of which exerts an antiseptic action.
CcHsNaSOi + HgO = CeHg.OH + NaHSOi
The Zinc Salt, Zn(CgH40.HS03)2, has in addition the antiseptic
and astringent properties of zinc.
Vigier * who has studied the relative antiseptic value of the three
isomeric phenol sulphonic acids, asserts that the ortho-acid is the
most energetic.
Sozo-iodol, a derivative of one of the di-iodophenols, obtained by
combining sodium paraphenolsulphonate with iodine, is sparingly
soluble in water, but easily soluble in alcohol or in glycerine.
Its iodine is liberated by the action of light. It has been used
locally in nasal and pharyngeal disorders, and in parasitic skin
affections.!
Sozo-iodol-mercury contains 31 -2 per cent, mercury and 38 per cent,
iodine. + Draer has studied the action of both these compounds on
the cholera bacillus.§
Aseptol is an ill-defined mixture of phenyl ethers and sulphonated
phenols prepared by the action of sulphuric acid on phenol in the
presence of alcohol. ||
Sozal is described by Dr. Schaerges of Berne, as aluminium para-
phenolsulphonate (OQH^OHSOy)QAl.,. "It is a bactericide having the
advantages in surgery that corrosive sublimate possesses, without
its toxicity. It occurs in small crystals which have a strong
astringent taste and only a slight odour of phenol. The salt is
readily soluble in water and glycerine, and also in spirit." If these
high claims are justified it will be of great value in surgery.
* Joum. Pharm., [5], vol, xi., pp. 145, 214.
t Brit. Med. Joum., 1889, vol. xi., p. 42.
* Pharm. Joum., 1889, p. 577.
§ Am. Journ. Med. Sci., March, 1894.
II Serrant, Jahresherkht f. Thierchemie, 1885, p. 499.
ORGANIC SUBSTANCES.
159
Hueppe describes a sulphonic derivative of phenol-orthophenyl
sulphonic acid, which is less caustic and more antiseptic than the
parent substance.* Kaemar f covers the use of certain sulphonatea
as disinfectants.
Benzene-Sulphonic Acid, S02(OH)CgH5, an acid liquid obtained
by adding benzene cautiously to sulphuric acid with 30 per cent, of
sulphuric anhydride, is patented by Giles and Shearer X as an
antiseptic, disinfectant, and deodoriser. They minutely describe its-
preparation and purification. It is a question whether it would be
superior to sulphuric acid alone. It is the source of synthetical
carbolic acid (p. 150).
There are numbers of other sulphonic acids, but at present they
have no special interest as disinfectants, but it will be noted that
sulphonating reduces the poisonous action of both the hydrocarbons
and the phenols without destroying their disinfecting properties^
Further comparative experiments with known organisms with the
same weight of compound with and without a " sulphonic group ""
would be of value. The sulphonates of hydrocarbons containing
more than one closed chain should be especially active.
Phenyl-substituted Fatty Acids. — Klein § showed that phenyl-pro-
pionic acid has a niore powerful antiseptic action on anthrax bacilli
than phenyl-acetic acid. J. Parry Laws || has further shown that
phenyl-butyric acid restrains the growth of anthrax bacilli when pre-
sent in the proportion of 1 in 2500, and that it kills the sporeless-
bacilli when they are exposed for thirty minutes to a solution of 1 in.
1000, or for ten minutes to a solution of 1 in 700.
The followinji table shows the relative value : —
Phenol.
Phenyl-Acetic
Acid.
Phenyl-
Propionic Acid.
Phenyl-Butyric
Acid.
Restraining Power, ,
Killing Power, .
Length of Exposxire, .
1 in 700
1 in 200
45 mins.
not determined
1 in 450
30 mins.
1 in 1900
1 in 600
30 mins.
1 in 2500
1 in 1000
30 mins.
Thus they increase in antiseptic power with increa.se of molecular
weight. Duggan H has shown that the converse is true in the case of
the fatty acids when tested on B. subtilis. His results give —
Formic Acid.
7 per cent.
Acetic Acid.
9 per cent.
Propionic Acid.
12 per cent.
* Brit, Med. Joum., 1891, p. 1107; also on the Sulphocarbolates see Joum,
Soc. Chem. Ind., 1889, p. 912. t Patent No. 3933, 1892.
jPatent No. 14,864, 1887. § ThirUenth Annual Report L. C. B.
II Chem. News, 1895, p. 15. IT .4m. Chem. Journ., vol. vii., p. 62.
160
DISINFECTION AND DISINFECTANTS.
These percentages almost exactly correspond to their relative molecular
weights, and consequently to their relative saturating power of bases.
CRESOL OR CRESYLIC ACID AND THE HIGHER PHENOLS.
The higher phenols may be regarded as derivatives of phenol in
which one or more of the hydrogen atoms of the " benzene ring " have
been replaced by methyl or other fatty radicles. These substitution
products form a homologous series of progressively increasing density
and boiling point, of which the following are known : —
Table of the Phexol Sebies.
„ X .. ».. Commercial
Systematic Name. Name.
Empirical
Fonimla.
Rational Fommla.
Phenol, . . . Carbolic Acid.
Methyl-Phenol,., .{ gSjlirAcid.
Dimethyl- Phenol, . Xylenol.
Triniethyl-Phenol. . Cumenol.
Tetramethyl- Phenol, , Durenol.
CcHcO
} CyHgO
CsHjoO
C9H12O
C10H14O
CJI5 . OH
CcH4(CH3) . OH
C6H.,(CH3)2 . OH
CbH2(CH3)3 . OH
CcH(CH3)4 . OH
Of all, except the first, several isomerides are known. They are
all antiseptic ; as to their relative values the authorities differ, but
.all agree that there is not much difference in power between phenol
and the cresols. All dissolve in strong alkalies, giving soapy anti-
septic solutions, but the compounds of the higher members of the
series are decomposed by water, yielding milky emulsions which
slowly deposit the oil. They are less poisonous than phenol, and are
classed together as phenoloids.
A mixture of these bodies from which phenol had been separated
formerly constituted a waste product of the carbolic acid manufacture
under the name of "creosote oils," and was used for preserving
timber, &c. They are difficult to separate by fractional distillation,
and now in various mixtures they are largely used for disinfectants
under fancy names, such as Creolin, &c. Some of them contain also the
hydrocarbons, or neutral tar oils.
The waste gases from blast furnaces, formed by the destructive
distillation of the upper layers of coal and bituminous iron ore, when
cooled deposit large quantities of empyreumatic products, from which
is manufactured on a large scale in Scotland the mixture called " blast-
furnace creosote oil " for creosoting timber. It contains 20 to 35 per
cent, of phenoloid bodies soluble in caustic soda, the coal-tar creosote
oil made in London only containing 5 to 10 per cent. Watson Smith
found one sample of the phenoloids obtained from blast-furnace tar to
contain only 133 per cent, of phenol, having a boiling point of 182° C,
ORGANIC SUBSTANCES. 161
while those obtained from Lancashire tar contained 65 per cent, of
crystalisable carbolic acid (the phenol may have been previously
separated from the former). The fraction that would contain cresol
had 4 "5 per cent, of phenoloids, and the fraction boiling from
210° to 230° consisted of a mixture of the xylenols and cresols.
The " creosote oil " is treated with caustic soda, the insoluble
hydrocarbon oils separated, and the soda compound decomposed by
the waste gases from the furnace. Sodium carbonate is formed, setting
free the phenoloids. The carbonate of soda is treated with lime,
giving fresh caustic soda for another quantity of oil. The crude
phenoloids are distilled, yielding the "creosote" of commerce. It
contains about 1 to 2 per cent, of phenol, a large quantity of cresols,
and a smaller quantity of the higher homologues. The oxyphenols,
similar to those found in wood creosote, are present only in very
small quantities.
Schulze* has found in coal-tar cresols 40 per cent, meta-cresol,
35 per cent, ortho-cresol, and 25 per cent, para-cresol.
When fresh, creosote is almost as colourless as water, but it
gradually darkens on keeping, slowly forming tarry products of less
potency. It is quite as good an antiseptic as crude carbolic acid,
and has not such a caustic action on the skin.
Buchholtz states that the least quantity of creosote that would
prevent bacteria from developing in Pasteur's fluid f was 1 in 2,000.
Creosote has a strong power in checking fermentations, hence
its name (xpsag, flesh ; ffw^w, I keep). Although only slightly soluble
in water, its solution has preservative powers. It has been used for
preserving organic putrescible liquids, and for keeping meat, &c.,
but its taste and odour are more unpleasant than those of the
"creosote" from wood tar. It is administered internally to check
fermentation in the stomach, but is a dangerous and unpleasant
remedy, as it suspends digestion. Inhalations of coal-tar creosote
vapour have no effect on phthisis, but are useful for cases of foetid
expectorations arising from bronchiectasis (Chaplin).
With reference to the antiseptic power of these creosotes, it has
been asserted with some show of probability that mixtures have
often been found to have more energy than any of the ingredients
used singly. This may be due to the fact that different species of
organisms have quite distinct susceptibility to different agents,
Lacroix Hunkiabeyendian states that a mixture of ortho-, meta-, and
para-cresol exerts a stronger action upon microbes {Staphylococcus
* Ber. d. Chem. Gesells., vol. xx., p. 410.
tlOgrms. sugar, 1 grm. ammoDinm tartrate, and 4 grm. potassium phosphate
in 100 c.c. of distilled water.
11
162 DISINFECTION AND DISINFECTANTS.
pyogenes aureus, Tetragonus prodigiosus, and the bacilli of cholera
and typhus) than any of the purp compounds used singly,* As the
solubility of the cresols in water is increased by the presence of a-
small quantity of the sodium compound, there is therefore some excuse
for the complicated nature of many of these patent specifications.
Bacillite. — Hopef treats the sewage, &c., in suitable tanks with
a current of "antiseptic steam" till deodorised (1). The antiseptic
steam is generated from a solution of 1 gallon of "bacillite" (composed
of cresylic oil 8 parts, sulphur ^ part, sodium hydrate 2 parts, sodium
carbonate 1 part, resin 2 parts, boiled for two hours) "or other
suitable disinfectant," in 200 gallons of water. "This quantity is
sufficient to disinfect 4,000 gallons of sewage." But it will be noticed
that most of the ingredients are non-volatile, and would not pass-
over with the steam; in fact, the soda would hinder the cresol from
volatOising. It would seem better to add the "bacillite" to the
sewage and then pass in steam.
Lysol, prepared by Schulke and Mayr, of Hamburg, is a brown
transparent syrupy fluid which turns litmus blue "but contains no
free alkali." The ash is about 6 per cent, and is mainly carbonate
of potash. Lysol contains about 51 per cent, of volatile oils, consisting
of higher phenols, and no carbolic acid. It is miscible with water in
all proportions, hence it can be used of any strength. Dr. Schottelius |
gives the minimum effective strength of the following in per cents. : —
Lysol.
Kreolin.
PhenoL
Staphylococcus pyogenes aureus.
Typhus bacillus, ....
0-3
1-2
1-2
2-5
Pearson's kreolin (Jeyes) was used. Lysol of 'SS per cent, destroyed
in twenty minutes cholera and typhus bacilli. § The English patent for
lysol II describes it as " tar oil mixed with a fat or fatty oil, and saponi-
fied with alkali in presence of alcohol. Homogeneous and soluble."
Lysol is thus a mixed disinfectant produced by dissolving in fat,
and subsequently saponifying, with the addition of alcohol, the
fraction of tar oil which boils between 190° and 200° C. (practically
the cresols, excluding almost all the less soluble xylenols, &c.). It
is a brown, oily-looking, clear liquid, with a feebly aromatic creosote-
like odour. It contains 50 per cent, of cresols and is miscible with
• /. de Pharm. et de Chemie, 1892. t Patent No. 17,924, 1891.
J Miinchener Med. Wochenschr., 1890, No. 20.
§ Engler, Dingl. pol. J., vol. cclxxviii., pp. 26 to 78 ; J cum. Soc. Chem. Ind.,
1890, p. 1,136. II Damman, Patent No. 1,017, 1890.
ORGANIC SUBSTANCES. 163
water to a clear saponaceous, frothing fluid. It shows turbidity when
mixed with hard water from the formation of the well-known preci-
pitate of lime and magnesia soaps, but its disinfectant quality is not
impaired thereby. It acts to all intents and purposes as a soap ; and
seems well adapted for use in surgical operations. Lysol forms a clear
solution with alcohol, glycerine, «kc.
It removes all dirt, fatty and resinous spots from the skin, as well
as from linen, instruments, and the like.* To remove the soapy
feeling, the hands may be rinsed in sterilised water, and dried with
a sterilised towel.
Gerlach and Simmonds tried it on infected faeces with success.
Cramer and others recommend it for surgery. Prom these reports
lysol appears to be an efficient preparation for surgical purposes, but
its mode of preparation would seem to make it too expensive for use
in large quantities for public disinfection.
Pixel {Eberman and Raptschev:ski) is made by slowly adding a mix-
ture of 3 parts of tar and 1 part of "green soap," heating, if necessary,
to 3 parts of a 10 per cent, solution of caustic soda. A clear brown
liquid, miscible with water, results. " A 5 per cent, solution has the
same power as lysol of the same strength, and is cheaper." The
Lancet, Oct. 14, 1893, states that this disinfectant was found useless
in the cholera wards of the Obrickooski hospital at St. Petersburg.
The solution of tar does not kill cholera bacilli, and has only a slight
inhibitory power on their growth.
" Fizene " is a preparation of the same class, made by Wheeler from
light tar oils. It mixes readily with water.
The real question at issue is — Should a disinfectant be easily soluble
in water or not? On the one hand, it is obvious that to penetrate
through the envelopes of bacteria requires an agent which is in solu-
tion, and therefore diflfusible. But Mr. Worrall, the inventor of the
Thorncli£fe disinfectant, now called " Izal," takes exception to such a
conclusion, and claims that " insolubility in water is one of the most
valuable properties of this preparation, since when once applied to a
part requiring disinfection it is not easily washed away, and therefore
fulfils its purpose more effectively."
There is no doubt that emulsions of tar oils have several sources
of popularity with the public ; they look strong, their odour enables
their presence to be felt, and their appearance enables one to judge
when they are properly mixed, instead of falling to the bottom of the
liquid, like solid disinfectants, or floating on the top and being carried
away, like phenol. Moreover, the minute oily globules in these
emulsions do slowly dissolve, and exercise a strong inhibitory action
• Engler and Dieckhoff, Arch. d. Pharm., voL cczxx., p. 562 ; vol. ccxxxii., p. 351.
164 DISINFECTION AND DISINFECTANTS.
on the germs for long periods of time, so that the sewage may be
carried away before it has a chance of conveying infection.
The best of these preparations may be regarded as strongly anti-
septic and useful against infection, though it must always be remem-
bered that, as Klein has pointed out in anthrax, Karlinski in excreta
of typhus, and Kitasato in cholera stools, the matter apparently dis-
infected, in which no growth may appear for days, if it be removed
to fresh sterilised excreta [Kitasato), or inoculated into the blood of
fresh subjects [Koch, Klein, Blyth, *tc.), will often begin to grow and
prove fatal, the spores having been stupefied and not killed.
Here the emulsified and slowly dissolving oil might have a distinct
advantage, as, so long as sufiicient of it remained, the spores would be
prevented from growing.
Another soluble preparation closely resembling lysol is Tricresol,
introduced by Scherings, of Berlin. It is a mixture of the three
cresols found in coal tar — viz., the ortho-, meta-, and para-cresol —
"has the advantage over carbolic acid of being non-toxic, and is
superior to other cresol compounds in being soluble in cold water."
Tricresol is synthetically prepared from toluene, CgH5(CH3). Accord-
ing to Professor Gruber, water dissolves from 2-'l to 2-5 per cent, of
tricresol ; but a 1 per cent, solution only is required in surgery, " that
being equal in antiseptic power to a 3 per cent, carbolic acid solu-
tion." * Tricresol is at first perfectly colourless, has the odour of
creosote, and boils from 183° to 205° C, the fractions being —
Below 183° = ... per cent.
183° „ 185° = 4-3 „
185° „ 190° = 5-3
190° „ 195° = 560
195° „ 202° = 34-4
100-0
" As phenol boils at 183°, and the cresols between this temperature
and 202°, it follows that phenol, xylenol, and the other members of
this series are practically absent. The specific gravities of the fractions
are 1"04;2 to 1*049 at 20° C. It is stated to contain 40 per cent, of meta-,
35 per cent, of ortho-, and 25 per cent, of para-cresol." The following
table gives the physical properties of these three compounds : —
Boiling Point Melting Point.
Spec. Gravity.
Orthocresol, .
Metacresol, .
Paracresol,
191° 30°
203° 4°
202° 36°
10053
105
•996
Crystalline.
Liquid.
Prisms.
* Pkarm. Zeitung, 1894, No. 4; 1895, No. 97; Archiv.f. Hygiene, voL xvii,,
p. 6ia
ORGANIC SUBSTANCES. 165^
Von Heyden asserts that the higher phenols are rendered soluble
by mixing with sodium salts of acids like benzoic, salicylic, &c*
The British Medical Journal, 1891, p. 414, states that a mixture of
soluble tar products with sodium salicylate and water under the name
of "resole" made a solution which was very effective. Engler and
Dieckhoff have recently made an exhaustive examination of those
cresol preparations which are soluble in water. f
Among the emulsions containing cresols the more important are
Jeyes' disinfectant and creolin.
In the first patent I " resin and creosote or naphthalene are heated
with .soda." Patent No. 5,249, 1877, proposes " coal-tar distillates
above a 1,000 specific gravity" (this would include phenol and a large
number of other bodies) "to be mixed with resin, soda, and vegetable
oils" (giving a resin soap and a fat soap) "so as to make a milky emul-
sion with water." An anthracene salt (?) or naphthalene also may be
added. This very complex mixture seems to have been the original
form of "Jeyes' disinfectant," a dark brown, syrupy liquid which gave
a brownish-white milk easily diffused through water, a large proportion
of the oils, etc., remaining quite insoluble. In its original form it
had an unpleasant .smell and left dark tarry stains on the floorings
&c. It has since been considerably improved, containing more of
the cresols, and not so much of the naphthalene and neutral tar oils.
Another application § melts together resin, naphthalene, and pitchy
mixes with soda or potash, and makes into cakes, which are broken;
up and dissolved in water when wanted. Unless there were a.
great proportion of alkali, the "solution" in water would be very
slow, and would require a great deal of stirring.
It may here be mentioned that potash, the basis of lysol, saponifiese
more rapidly than soda, and the product, being a soft soap, is more
soluble than the hard soap made with soda. The mixture of the two
alkalies is therefore advantageous.
For drains, ifec, the fluid is directed to be mixed with 50 parts o€
water. It is also recommended for gargles (a teaspoonful to a pint),
as spray, and for fumigation ; here it would have the same limitations
as other preparations of slight volatility.
That Jeyes' fluid and creolin are non-poisonous, or at least far
less so than phenol, is proved by a recent case in London where a
woman took 4 oz.s. of Jeyes' fluid with the object of committing
suicide, but was not injm-ed. The British Medical Journal, Jan. 11,
1890, also cites a case in which a man took nearly 9 ozs. of creolin
with the same object. " He soon became unconscious, but waa
* Patent No. 9,103, 1890. t Archiv. der Pharm., No. 232, pp. 351-365.
* No. 4636, 1877. § Patent No. 2,669, 1882.
IS6' DISINFECTION AND DISINFECTANTS,
discharged, cured, in the third week after admission." Such a result
would have been impossible with carbolic acid.*
Creolin is a more refined preparation by the same makers. It
contains mainly the cresols as alkaline salts, without phenol or
other tar products. It is a brownish-black alkaline syrupy liquid
of empyreumatic odour, giving a soapy emulsion with water, f
The bacteriological reports on these two fluids are very favourable.
Dr. von Esmarcli in Koch's laboratory at Berlin found that " 1 per
mille killed the cholera bacillus in ten minutes, whereas carbolic
acid took four days." Dr. Eisenberg, of Vienna, states that 6 per
cent, of it killed even anthrax spores in twenty-four hours, while
phenol did not destroy them in a week. " Spores of the hay bacillus,
which possess the greatest power of resistance, were killed by 6 per
cent, of creolin in six days ; phenol failed.
Dr. Washbourn J repeated the experiments of the two previous
observers with confirmatory results. He concludes that "creolin is
a good antiseptic, certainly superior to carbolic acid in its action
on sporeless bacteria, and probably superior also when acting on
spores." He finds that 5 per cent, creolin is equal to 1 per cent, of
mercuric chloride.
Oreolin and Jeyes' fluid have found great favour in hospitals for
warm baths in infectious and skin diseases. Their results are certainly
very good. But for sewage, fumigation, ttc, " disinfection" cannot be
maintained, as it is proved by experiments that 5 per cent, is required
to destroy all pathogenic organisms, and the cost of this would be
almost prohibitive.
Lano-creolin, soaps, gauze, &c., are also made, and "capsules" con-
taining 5 minims each.
" Smith's Carbolated Fluid " (Hampton Works, Borough Road,
London) turns milky with water, and seems to be of similar nature
to the above. So is " Artmann's creolin " (Julius Sommer, Stuttgart)
specially used for soaps (Hof & Co., London Agents).
The Strathclyde Chemical Company are manufacturers of a disin-
fectant which is a residual product of a kind of blackstone shale at
the Dorset mines. "This shale is remarkably light, yet it contains
oils of a very heavy and volatile character. These oils when distilled
are said to possess valuable insecticide and deodorant qualities.''^
These shale oils contain a large quantity of the pyridine series of
bases to be described later (p. 189).
Essets Fluid is an alkaline solution of higher phenols similar to
Jeyes' fluid, giving, like it, a milky emulsion with water. The Lancet,
* See ibid., 1891, p. 49, for a confirmatory case. t See Lancet, Jan. 5, 1889.
J Guy's Hospital Reports, vol. xlv., 1888. § Chemist and Druggist, 1891, p. 39.
ORGANIC SUBSTANCES. 167
July 1, 1893, pronounces it "an efficient disinfectant and antiseptic."
It may be mentioned that the strength of solution recommended to
be used for closets, drains, &c., viz., one teaspoonful to a gallon of
water, or 1 in 320, is much too dilute to be efficient.
Saprol, introduced by Dr. Nordlinger of Bockenhein, Frankfurt, is
a dark brown oily liquid smelling like crude carbolic acid, having a
mean specific gravity of 0'990, therefore floating on aqueous solu-
tions.
According to the analysis of Dr. Spindler of Stuttgart, it contains
phenol and cresol, 43-0 ; hydrocarbons, 53*9 ; pyridine and other bases,
2-8 = 99-7.
When poured into water a separation occurs, the heavier cresols
partially dissolving and partially sinking in drops, while an oily scum
of the hydrocarbons floats on the liquid. This covering, according to
Professor Quincke of Heidelberg, amounts to 0*2 milligramme per
square millimetre. Scheurlen* finds that when saprol is thus poured
upon water, and left to stand for three or four days, from 33 to 39 per
cent, of it dissolves — that is, the greater part of the cresol and phenol,
of which it contains 43 per cent. The liquid contained 0-41 to 0*49
per cent, of cresols. He proved that either crude phenol or saprol
itself, even if .shakei repeatedly for seven days with water, only yielded
solutions of 0"45 to 0'51 per cent, of cresols, so that he concludes that
0*5 per cent, is the mean solubility of the cresols, and that the latter, if
time be allowed, dissolve just as well when merely poured on water,
as when continuously and vigorously stirred. " This fact, applied to
the disinfection of faecal matters, proves that by the use of saprol a
mixture of the faeces supersaturated with the disinfectant is obtained."
Dr. H. Gross found that the addition of dilute alkalies or acids did
not increase the solubility. It is also pointed out that while the
uniform coating of saprol entirely prevents contact with the atmo-
sphere, so that no evil-smelling gases can be emitted from the faeces,
the usual oxidation process is also checked, while the soluble parts of
the saprol gradually penetrate right through the mass.
According to Laser,! a thin layer of saprol kept urine clear, without
smell and sterile, for twenty-two days. A thick layer sterilised
anthrax cultures in twenty-four hours. Urine, which had been stand-
ing under a thin film of saprol for twenty-three days, was filtered and
mixed in three glasses with (1) cholera vibrios, (2) typhus bacilli,
and (3) Staphylococcus pyog. aureus. In all three glasses the micro-
organisms were killed. He also made a series of researches with
increasing quantities, to ascertain the amount required to disinfect
and deodorise urine, and, as a result of his experiments, concluded
♦ Archm.f. Hyg., 1893. t Centr.f. Bacteriologit, 1892, toL xiL, p. 78.
168 DISINFECTION AND DISINFECTANTS.
" that 1 per cent, of saprol is sufficient for the disinfection of fseces
and urine."
Scheurlen * confirms these results. It must be remembered that a
1 per cent, solution of saprol is equivalent to about 0*34 per cent,
solution of the cresols.
The special claim of saprol is its peculiar physical action — viz.,
" being a little lighter than water, partially soluble and partially
insoluble " — by which it —
1. Forms a complete coating over the substances, so keeping them
from the atmosphere, and masking smells.
2. Diffuses gradually and evenly through the putrescent matters,
first restraining and then killing the organisms.
3. Acts in less strength (1 per cent.) than phenol (2i per cent.).
As to cost, it is stated that " 1 litre per month, costing 60 pfennige,
is sufficient for a household of twenty people, or 3 pfennige per month
per head."
It must be admitted this is a very strong case for saprol. It
and lysol are much used in Germany, the former for common, and
the latter for surgical purposes. It is to be noted tliat saprol retards
the n£.tural decomposition of sewage by oxidation ; unless the excreta
be removed quickly they will be liable to grow organisms again, as
even with such cheapness it would be difficult and expensive to attain
so high a strength as 1 per cent. A similar reservation applies to all
this class ; they are really more antiseptic than true disinfectants, and
their action as deodorants is simply that of a mask.
The presence of pyridine (which is very soluble) must not be for-
gotten. Neither sulphuretted hydrogen nor ammonias would be
effectively absorbed ; hence it would be advisable to use one of the
chemical absorbents as well.
The flashing point of saprol is 90° to 100° C, about the same as that
of phenol, and sufficiently high for safety under ordinary circum-
stances. Unless heated, a light applied to it does not cause it to
inflame.
In some of these preparations containing the higher phenols, ozone
is said to be produced when they are exposed to the air.
With Allen's " hygiene disinfecting fluid " this is said to be the
case, but as this fluid is recommended to be used at a strength of
1 in 500, and the evidence of all experiments go to prove that 1 per
cent, is the lowest effective dilution for any tar preparations, these
statements require confirmation.
As to the production of ozone, Dumas f endeavoured to explain the
slight deodorant properties of the tars in the light of the experiments
♦ Arch. f. Hyg., 1893. t Acad, des Sciences, July 25, 1859.
ORUAXIC SUBSTANCES. 169
of Schonbein on the abundant formation of ozone in air mixed with
the vapours of essence of turpentine, but later experiments have shown
that in all probabilitj' more hydrogen peroxide than ozone is jjroduced
by the phenols in the presence of air and moisture.
IzaL — In the process of carbonising coke in close ovens, a tarry oil
condenses, which contains some of the higher phenols. From it
J. H. Warrall has obtained . a clear deep, reddish-brown liquid
insoluble iu, and of greater density than, water. Its mean boiling
point — i.e., it is a mixture — "is considerably higher than that of
carbolic acid (400° F.), and it has not the caustic action on the skin
as has that antiseptic ; moreover, it is non-poisonous to the higher
animal life." This insolubility and high boiling point " insures the
antiseptic body remaining upon the part requiring disinfecting after
it has once been there deposited." It remains permanently suspended
iu water, forming a milk-white emulsion, and is hence easily distri-
buted by water. " It remains liquid at all temperatures above 32° F.,
while a temperature of 212° F., instead of deteriorating, only tends to
concentrate it. It mixes readily and perfectly with water in all
proportions."
It was originally called the " Thorncliffe disinfectant," but is now
known under the name of "izal."
Mr. "Warrall tried izal on the Acarus of the sheep, and found one
treatment to effect complete cure, "proving that not only were the
parents destroyed, but the antiseptic body remained to destroy also
any insects hatched from the eggs which the parents had deposited
previous to their death" ("the time of egg-incubation and larva-develop-
ment is ordinarily fifteen days"). This seems to be a far more legitimate
inference than that the eggs themselves had been destroyed.
Klein, after a bacteriological investigation, reported that izal had
"a quite remarkable bactericidal effect." According to Dr. Klein,
0'25 C.C. administered to a rabbit, both subcutaneously and by the
mouth, had no effect on the rabbit's health or appetite, and Mr.
Warrall states that 10 drops have been taken with impunity.
Dr. Klein states that "an exposure for five minutes to izal in the
strength of 1 in 200 completely destroys the vitality of the microbes
of diphtheria, typhoid, fowl-cholera, swine fever, glanders, cholera,
suppuration, erysipelas, scarlatina, and other non-sporing pathogenic
and non-pathogenic species."
With reference to spores he continues: "The result of all experi-
ments on inhibition may be briefly summarised for all the twenty-five
species tested — namely, (1) spores do not germinate in medicated
gelatine or broth if the amount of disinfectant added be 01 per cent.;
(2) no microbes (Staphylococcus and Streptococcus) are capable of grow-
170 DISINFECTION AND DISINFECTANTS.
ing in medicated gelatine or broth of the strength of O'l per cent.
medication ; (3) all non-sporing bacjlli and spirilla fail to grow in the
above 0-1 per cent, fluid; (4) excepted from this are the Bacillus
prodigiosus and the bacillus of typhoid ; the former shows growth on
gelatine medicated 0*1 percent.; the growth is retarded, and always
starts from the superficial layer of the medium ; it proceeds consider-
ably slower than on normal gelatine."
Dr. Bruce Clarke, of St. Bartholomew's Hospital, gives a very
favourable report of its use in surgery.* With regard to Dr. Klein's
•exceptions he says that they " obviously do not concern one from a
surgical point of view, inasmuch as B. prodigiosus is not a pathogenic
•organism at all, and the bacillus of typhoid fever does not enter
"wounds."
He also observes that, " being an emulsion and not a clear solution,
it is not so easy to see one's instruments when they are covered with
it. At the same time it must be borne in mind that the very fact that
the fluid is so singularly unable to form chemical compounds with
living animal tissues is in all probability highly advantageous from the
germicidal point of view. Unlike corrosive sublimate, which speedily
loses its disinfectant power by combining with the albuminous sub-
stances of the body, izal retains this power in such a remarkable degree
•because it will not combine with anything. It is also at the ordinary
temperature of the body non-volatile, as may be easily seen by placing
a few drops on a piece of cotton wool and leaving it several months in
an exposed position." It is to be inferred that : —
(1) Izal seems, in a strength of 1 in 200, to be a disinfectant, and in
1 in 1,000 to be more antiseptic than phenol.
(2) Not being volatile it must be strictly local in its action,
like chloride of zinc. Hence it is doubtful if to "saturate a sheet
and suspend it before the door of a room" has much beneficial
action.
(3) The quantities recommended, namely, "for sprinkling rooms,
1 tablespoonful with 5 pints of water," and for sewers and public dis-
infection, " 1 gallon in 100 gallons of water," are higher than those
usually proposed for most other "disinfectants," being about 1 per cent.
As Dr. Rohe says,t "There can be no partial disinfection of infectious
material ; either its infective power is destroyed or it is not. In the
latter case there has been a failure to disinfect, and the labour and
money have been wasted."
As a warning, however, it must be remembered that even the 1 per
cent., when used for sewage, becomes considerably diluted ; hence a
great deal more must be used. Here the expense, as with other disin-
• Lancet, July 1, 1893. t Text Book of Hygiene, 1890, p. 350.
ORGANIC SUBSTANCES. 171
fectants, become so heavy that, at the risk of repetition, it must be
laid down that the practical and complete disinfection of sewage by
any agent or process at present known cannot bo attained except at
great cost.
Lawes' disinfectant fluid and " Odamine " are similar commercial
cresol products used as disinfectants and sheep dips.
Europhene, isobutylcresol hydriodide, (CgH3(CH3)(C4H9)OH)2,HI,
is a product of the action of iodine on isobutyl-orthocresol. It is
insoluble in water and alkalies, but soluble in alcohol and ether. It
easily decomposes (liberating iodine), and behaves like similar organic
iodine compounds.
Resorcinol, or "resorcin," is meta-dioxy-benzene, CgH4(OH)2. It
is prepared by fusing sodium m-benzene-disulphonate with potash or
soda and extracting with alcohol.
Resorcinol occurs in minute needles, colourless when pure, but
turning reddish in air. It coagulates albumen, forming a white
precipitate. It only begins to be toxic in very large doses 10 to
20 grammes per day internally for an adult, while a 2 per cent,
solution is highly antiseptic (Vallin).
Andeer * Callias f Dujardin-Beauraetz J Lichtheim of Berne, and
others have experimentally demonstrated that resorcinol is a powerful
antiseptic. Callias proved that fermentation was prevented, and
many animal liquids preserved, by 1 per cent, of resorcinol, while
to keep milk required at least 2 per cent.
As to its internal action, Andeer, after a dose of 10 grammes of
resorcinol, experienced vertigo, dizziness, loss of smell, and salivation,
the symptoms disappearing in 5 hours with no after effects. It is
therefore, far less poisonous than phenol. Dr. W. Murrel§ has also
reported on its internal use.
Dujardin-Beaumetz employed the fine powder in diphtheria and in
syphilitic ulcerations with somewhat doubtful results. 1^ per cent,
of resorcinol gradually entirely sterilised the bacilli of typhoid.
It is evident that 1 per cent, of this substance is efficiently antiseptic
towards most micro-organisms. It has been employed in the treatment
of acute fevers, also as spray in diphtheria and whooping-cough. As
an antiseptic the dose is 5 to 20 grains.
Andeer's lotion is resorcinol 40 grains, water 1 ounce, as an anti-
septic and stimulant for foul sores and to allay chronici eczema and
psoriasis. II
* Ueber daa Resorcxn, Wurtzburg, 1880.
t Resorcxn en TMrapeutique, Paris, 18S1.
X Bull, de TMrapeutique, June and July, 18S1.
§ Med. Times and Oaz., 1881, p. 486.
li Squire'8 Companion to the B. P., 1890, p. 348.
172 DISINFECTION AND DISINFECTANTS.
For rendering rooms antiseptic M. Meilliere* recommends the dissi-
pation of phenols, &c., by heat. Napbthalin, anthracene, xylol, ordinary
phenol, cresols, naphthols, benzoic acid, oxybenzoic acid, salol, betol,
beuzonaphthol, chloral, formal, and mercury sulphides and chlorides
are indicated as useful for this purpose, but resorcin is particularly
recommended. It is best mixed with a little hydrochloric acid, and
the mixture should be heated in an open dish. Afterwards it is well
to evaporate rapidly 100 grms. of water, either pure or acidulated with
acetic or hydrochloric acid.
Pyrocatechol or pyrocatechin, ortho-dioxybenzene, CgH4(OH)2, is
obtained by fusing iodophenol or iodosalicylic acid with potash. Like
almost all products of destructive distillation it is antiseptic, but its
properties in this respect do not seem to have been studied. The
third dioxybenzene hydroquinone or quinol has also an antiseptic
action, but is not much used.
J. E. Dugganf has investigated the relative antiseptic power of the
three dioxy benzenes by noting the amount required to prevent Bacillus
suhtilis from developing in beef peptone. Taking phenol as 20, he finds
that the ratio of the three compounds ortho : meta : para = 20 : 25 : 30,
whilst pyrogallol is represented by 15.
Pyrogallol or " pyrogallic acid " is trioxybenzene, CgH.5(OH)3. It is
obtained by distilling gallic acid. It is inodorous, tastes astringent,
and is not corrosive. Its solution quickly turns brown in air, absorb-
ing oxygen ; if an alkali be present, the action is almost instantaneous,
the solution becoming dark brown. This property leads it to be
destructive to "aerobic" organisms — those which live in presence of
oxygen. Bovet, of Neuchatel, first examined its antiseptic action, J
and found that a 2 per cent, solution prevented putrefaction, ferment-
ation, and mould for some months, and that 3 per cent, was capable of
killing bacteria. Two per cent, solutions have no injurious local action
and disinfect very well ; but it cannot be used internally, as it reduces
and destroys the blood corpuscles, causing hsemoglobinuria. It blackens
steel instruments and stains the hands. The British Medical Journal
recommends a 2 per cent, solution as an antiseptic (1879, vol. i., p. 278).
"A 10 per cent, salve applied with a brush twice a day has been
recommended in psoriasis, § but Neisser records a fatal case where it
had been used freely as an ointment.|l
* Journ. de Pharm. [6], vol. i. , p. 82.
+ Amer. Chem. Journ., vol. vii., p. 62.
X Revue cChygiSne, 1879, p. 154.
§ Journ. of Pharm., vol. xxv., p. 377-
II Zeilschri/tf. klin. Med., 1879, vol. i., p. 88; Squire's Companion, 1890, p. 27.
ORGANIC SUBSTANCES. 173
WOODTAR AND OTHER PRODUCTS.
The substances which are formed during the destructive distillation
of wood in closed vessels are very numerous. They vary with the
nature of the wood and with the temperature of the distillation, and
are gaseous, liquid, and solid. Charcoal, of course, is left behind in
the retorts.
It may be mentioned here that the gaseous products of destructive
distillation of all organic bodies are antiseptic in nature, and many
proposals have been made to utilise them by blowing them through
sewage, &c., but the action is not sufficiently energetic.
The liquid portions are partly soluble in water. Wood spirit or
crude methyl alcohol, CH3OH, is obtained from them by distillation ;
it is strongly antiseptic, but is so volatile and inflammable that it is
best used for other purposes.
Pyroligneous Acid (discussed under Acetic Acid, p. 225), with methyl
acetate and acetone, are also among the volatile products.
The insoluble portion, which consists of wood-tar, is composed of a
mixture of various liquids, such as the hydrocarbons, toluene, xylene,
cymene, «fec. (the same as those from coal-tar, p. 148, but with little or
no benzene), the substance called wood-creosote, and solids, such as
paraffin, naphthalene, &c. The lower the heat used, the larger is the
proportion of oxidised bodies formed, and the smaller that of hydro-
carbons and gases. So that various specimens of wood-tar difier in
composition.
It is probable that many of the coal-tar disinfectants previously
described contain wood-tar products also.
The proportions of the different bodies obtained by distillation of
wood are approximately as follow : —
Charcoal, 25
Gases, 22
Wood spirit, 1*0
Acetic acid, 4*0
Tar, 7-5
Water and other bodies, 40*5
100-0
Stockholm Tar, obtained from the resinous wood of the pine, is
extensively used for preserving ropes and sacking. The smell is prin-
cipally due to the constituents of creosote, notably to the crystalline
body called pyroxanthin, which, though only present in small quantity,
is said to be one of the best preservatives. Stockholm tar contains
much resin, acetic acid, and oil of turpentine. When distilled it
174 DISINFECTION AND DISINFECTANTS.
leaves a black resinous substance which constitutes ordinary pitch,
and has been used in many patents for forming solid block disinfect-
ants. The specific gravity of the ordinary wood-tar of commerce is
about 1 "04 ; when poured on water a portion floats and some dis-
solves, like saprol.
Retinol is simply the product of distillation of ordinary resin. Its
antiseptic properties are feeble.
Resol is the name of a disinfectant which has been introduced from
Germany. It appears to be similar to creolin. It is made by saponi-
fying 1,000 parts of wood-tar with 9 parts of caustic potash, and adding
200 parts of " an indifierent body such as wood-spirit." (The latter
would, on the other hand, add considerably to its antiseptic power and
aid in the saponification.) Resol is said to be an active bactericide,
killing typhoid, anthrax, and similar bacilli in five or ten minutes with
a 3 per cent, solution.
Wood Creosote contains some phenol and cresol, and quantities of
oxyphenols like guaiacol, creosol, and a little pyrocatechol. It is more
antiseptic than coal-tar creosote, and has a different and more agreeable
odour, but a more burning taste. It immediately coagulates albumen.
It is not easily inflamed, but when kindled burns with a smoky
flame ; it has been proposed to mix it with spirit and burn it in lamps
for fumigation, but the sooty flame so produced retards its use. If
swallowed in doses of more than a few drops it acts as a poison, so that
its internal administration must be attempted with caution. Though
sparingly soluble in water, the latter acquires from it its peculiar
odour, pungent taste, and much of its antiseptic power. Alcohol and
acetic acid dissolve it freely, so do the hydrocarbons of tar.
It combines with potash to form a crystalline compound ; solutions
of soda and ammonia also dissolve it. It is one of the most powerful
antiseptics known. Meat that has been plunged into a solution con-
taining 1 per cent, of creosote gradually becomes dry and hard on
exposure to air, and acquires the flavour of smoked meat, but does not
become piitrid. A considerable proportion of creosote (from 1 to 1^
per cent.) is held in solution in the crude pyroligneous acid obtained
during the destructive distillation of wood ; and on saturating this
acid at 167° F. with effloresced sodium sulphate, an oily matter which
contains a large proportion of creosote is separated. Crude pyrolig-
neous acid on this account is often employed for preserving hams and
salted provisions, to which it communicates the same flavour as if they
had been exposed to wood-smoke.
A great many patents relate to the manufacture of a disinfectant by
distilling peat; this would be mainly creosote. Unfortunately the
yield is small.
ORGANIC SUBSTANCES. 175
Creosote is used for carious teeth, for foetid ulcers, and in many
cutaneous affections, especially those tliat are parasitic.
J. Sommerbrodt, after nine years' trials, gave a most favourable
account of its action in tuberculosis. In doses of 1 to 4 grains per day,
in capsules with cod-liver oil, " it is well borne by the stomach and
does not decrease the appetite." * If applied to the skin in a concen-
trated state it produces a white spot like phenol, and the skin peels off"
without any attendant inflammation. Creosote dissolves many organic
bodies, such as camphor, the fatty and volatile oils, and many of the
resins. Therefore it has been a frequent ingredient in compound
antiseptic preparations. It is much more costly than the coal-tar
product, hence could not be employed largely in public sanitation ;.
and its smell in some cases has been known to produce nausea, head-
ache, and vomiting.
Reichenbach in 1830 discovered the antiseptic powers of creosote;,
after a long period of trial it fell into discredit, and now is only
employed for the uses above mentioned.!
Plants watered with creosote solution at once die ; hence it cannot
be used as a horticultural insecticide. Most micro-organisms are killed
by it in a strength of ^ per cent., and their spores are prevented from
developing. In very small quantity it prevents fermentation, the
action of diastase on starch, &c.
Bucholtz asserts that " 1 in 1000 was not sufficient to sterilise
vegetable infusions ; it required 1 per cent, to completely sterilise
germs and bacteria."
Guaiacol, methoxy-phenol or methyl-pyrocatechol, CgH4(OCIl3)OH,.
is a colourless liquid, becoming brown in light (therefore should
be kept in non-actinic bottles). Its odour and taste resemble creosote,,
of which it constitutes a large portion. It boils at 200° 0. Only
i per cent, of it dissolves in water, but it is more easily soluble in
alcohol, wood-spirit, acetic acid, and in alkalies. Sodium-guaiacol
resembles sodium-phenol.
Ferric chloride gives a brown opacity with the aqueous, and a.
blue colour with the alcoholic solution; hot sulphuric acid gives an
orange coloration. On shaking 4 c.c. of guaiacol with milk of lime
(10 grammes lime in 10 c.c. of water) white crystals of a lime-guaiacol
compound slowly form.
As the antiseptic value of wood creosote is due partly to the
guaiacol which it contains, it is important to note that recently this
ingredient has been removed from foreign creosotes.
* Berlin. Klin. Wochenschr., Oct. 19, 1891.
tSee a monograph by M. Labb^e in the " Dktionnalre des Sciences Medicodet,^'
art. Creosote.
176 DISINFECTION AND DISINFECTANTS.
The largest quantity (60 to 90 per cent.) exists in beech-wood
creosote, but it also has been obtained by distillation of guaiacum
resin, whence the name.
Its physiological value was first pointed out by Seidel in 1880
P. Marfori * finds that 1 part of guaiacol should dissolve in 60 of
water, and that impurities render it more soluble. It first excites,
then paralyses the nerve-centres, and reduces the temperature. Thera-
peutically it is similar to phenol and pyrocatechol, but not so poison-
ous. In a later paper f the same author states that its antiseptic
power is greater than that of phenol in the ratio of 5 to 2, and that
•0"5 to 1 per cent, destroys Bacillus ttibemdosis in two hours, while
other bacteria are killed with their spores in 20 to 30 minutes.
The hypodermic solutions known as Picot's, Pignol's, and Morel-
Lavallee's contain guaiacol.
It has been used for phthisis, administered in cod-liver oil or in
^vf^•lk spirit.
Guaiacol-carboxylate, C6H3(OH)(OCH,).COOH, is obtained by
saturating sodium guaiacol with carbonic acid, heating, and pre-
cipitating by hydrochloric acid. It is, therefore, a methoxy-salicylic
acid, and has naturally been credited with antiseptic and antipyretic
properties.!
Creosol, or methyl-guaiacol, C^H,j(CH3) (OCH.j).OH, is the chief
ingredient of ordinary wood-creosote. It resembles guaiacol, but has
a higher boiling point, is heavier, and less soluble. Its antiseptic
power is said to be a little higher.
A comparative study of creosol, guaiacol, and wood-creosote, with
and without the low boiling guaiacol, would be of value.
A disinfecting fluid called "soluble creosote," containing some
wood-creo.sote, is in the market. §
"Little's Soluble Phenyls," made by Morris of Doncaster, was at
one time in high repute in the north of England. It is recommended
by Dr. Rohe as a good disinfectant at a strength of 2 per cent.|| Prof.
•Corfield after lengthy experiments spoke highly of it. "It is non-
corrosive and non-poisonous. 1 per cent, in water is more powerful
than 10 per cent, of the best known antiseptics for wounds, ulcers,
and for use at post-mortems. The powder is also energetic against
vermin." It appears to be derived from wood-tar creosote, and would
take rank with the other preparations.
* Chem. Centralblait, 1890, p. 155. t Ann. dl Chimica, 1891, vol. xiii,, p. 3.
i See also Benzosol, chap, ix., p. 197. § Chem. and Drug., Oct. 26, 1893.
II Robe's Hygiene, 1890, p. 326.
ORGANIC SUBSTANCES. 177
NAPHTHALENE DERIVATIVES.
According to Bucholtz, diphenyl compounds or bodies containing
two carbon " rings," are more powerfully antiseptic than those
containing only one such grouj). The toxic behaviour of such com-
pounds is also diminished.
Naphthalene itself, CjQHg, has been already described (p. 148). It
is useful as an insecticide, but is not a disinfectant. It is employed
locally in scabies as a 10 to 20 per cent, solution in olive oil. It is
to be avoided where large surfaces are exposed. It is also used as an
antiseptic for wounds. Dr. Mirovitch considers naphthalene of high
value against ascarides and tape-worm, in doses of 15 grains, followed
by a large dose of castor oil.*
Some commercial " disinfecting powders " have been proved to
contain little else than naphthalene and earthy matters. It is hardly
necessary to say they are of little value.
Helbing states f that " the observations of Pavas, Dor, Hess,
Magnus, and Kolinski, among others, led to the conclusion that
naphthalene is unsuitable for use in medicines. It acts injuriously
on the optic nerves and the retina, and upon the kidneys. A small
quantity of camphor is said to largely cover its odour without affecting
its value as a preventive of moth."| Tidy advocated the presence
of naphthalene in the creosote used for preserving timbers.
Naphthalene-sulphonic acids, CjoH7(S02. OH). — By heating naphtha-
lene with concentrated sulphuric acid, two isomeric acids of this
formula are obtained. They are deliquescent crystalline substances,
soluble in water and strongly acid, and almost inodorous. The a-acid
changes into the /S-form when further warmed with suli)huric acid.
The resulting mass is dissolved in water, saturated with chalk, and
the lime salt crystallised (the a-salt remains in solution). Addition of
sodium carbonate will then convert it into the sodium salt, which
has been occasionally used as an antiseptic.
Naphthols, CjqH- . OH. — Each of the above sulphonic acids, when
fused at a moderate temperature with caustic soda, yields the corre-
sponding naplithol. These are purified by pressure, distillation and
crystallisation from hot water or petroleum ether.
a'Naphthol resembles the /3-form closely, but melts at 95° and boils
at 279° C, and with hot ferric chloride gives a violet colour.
^•Naphthol, as being more abundant, is the commercial article. It
crystallises in lustrous plates, smells like phenol, and has a hot and
tarry taste. It melts at 122° and boils at 286° C, and gives a green
* Lancet, 1891. + Modem Mat. Med., 1891, p. 64.
X See alao Fischer, Med. Times and Oaz., 1881, p. 718.
12
178 DISINFECTION AND DISINFECTANTS.
tint when heated with ferric chloride. Both the naphthols are readily
volatile with steam. The crystals should be colourless, should not
darken in light, should be neutral, and leave no ash on platinum.
It is almost insoluble in cold water, but dissolves in about 1 1 parts
of boiling water, in 2 of rectified spirit, in 1 g of ether, 24 of chloroform^
12 of olive oil, and in 4 of glycerine. It is a powerful antiseptic, and
was first proposed for skin diseases by Kaposi in 1881. It has been
given internally in diarrhoea in an emulsion with oil, and is very
effective in parasitic diseases and in chronic eczema* in ointment form
(3 to 10 per cent.), or in alcohol solution (2 to 10 per cent.) (Helhing).
A daily dose of 38 grains will produce intestinal antisepsis. It has
also been used in typhoid fever, f A solution of 1 in 1,000 has been
successfully used for preserving anatomical preparations.
Prof. Bouchard, in a report to the Academie des Sciences in 1888,
detailed certain experiments on the antiseptic power of /3-naphthol.
He says that he found 0*4 grm. of it to have the same efiect as '025
grm. of mercuric iodide, 2 grms. of phenol, 1"6 of creosote, 1*27 of
iodoform, 27 of iodol, or 1-51 of naphthalene. J He values it highly
for external use. "But what is more important is, that it appears to
be the most efficient agent for intestinal antisepsis, on account of its
slight solubility, which prevents its absorption, and allows it to
remain a long time in the intestine without any poisonous effects.
A dose of 1 grm. per kilo, of body-weight may be administered without
danger." §
Lesser and Neisser recorded symptoms of poisoning by jS-naphthol,
which Shoemaker attributed to impurities ; a conclusion largely con-
firmed in 1888 by an exhaustive examination of this drug by Willing.||
Dr. A. G. Gibson,1I of the Edinburgh Medical Infirmary, used
2 grains of /3-naphthol two or three times a day for the antiseptic
treatment of pernicious anaemia. In a large number of cases, im-
provement was extremely rapid when iron had been used before.
Dr. Gibson finds that irritation is sometimes caused by the drug, and
to prevent this he administers it together with a bismuth preparation,
such as the salicylate.
It has been recently observed that a-naphthol and salol (p. 199)
when rubbed together form a liquid. /3-naphthol, on the other hand,
does not liquefy, but, like many other substances, it becomes a
permanent fluid when melted with camphor, so forming " camphorated
• Med. Times and Gaz., 1882, vol. xi., p. 505.
+ Brit. Med. Journ., 1888, vol. xi., p. 1226.
J The experiments make naphthalene a stronger antiseptic than phenol, Year
Booh ofPharm., 1888. § Brit. Med. Journ., 1888, p. 1185.
II Helbing, Mod. Mat. Med., p. 53, IT Edin. Med. Journ., October, 1890.
ORGANIC SUBSTANCES. 179
)8-nap]ithol," used, according to Fernet, with great success for boils,
coryza, angina diphtheritica, and tuberculosis. Against the latter it
was given by injection in doses of 2 grms. mixed with oil.
Reboul cured twenty -one out of twenty-seven cases of tuberculous
glands by emptying any abscess formed, and injecting 7 or 8 drops of
camphorated naphthol, repeated every two days. Similar results are
recorded by Nelaton.*
Betel, naphthol salicylate, CgH^(OH).CO.OCiQH-, is a white, crystal-
line, inodorous, and tasteless powder, neutral, insoluble in water and
in glycerine, difl&cultly soluble in alcohol and turpentine. It dissolves
in 3 parts of hot alcohol, in ether, benzene, and in wanaa linseed oil.
Melting point, 95° C. Hot acids or alkalies reconvert it into salicylic
acid and iS-naphthol. It is prepared similarly to salol (p. 199). Anti-
septic ; now almost disused.
" Microcidine," chiefly composed of sodium-/3-naphthol, OjoHyONa,
also contains phenols. * Prepared by the action of soda and heat on
/3-naphthol. It is more soluble but less antiseptic than the latter, and
is somewhat irritant and caustic. It possesses no special advantage.
"Alumnol." — By heating the naphthols with sulphuric acid, several
naphthol-sulphonic acids are obtained. Certain of these, saturated
with aluminium hydroxide, give an aluminium salt to which the above
name is applied. Alumnol contains 5 per cent, of aluminium. It is a
white stable powder, very soluble in water, and soluble in alcohol with
a blue fluorescence. It dissolves in glycerine, but not in ether. It is
slightly acid. With albumen and gelatine it forms precipitates which
are readily soluble in excess. " Judiciously employed it produces no
injurious effects. Very large doses are required to produce any toxic
action on animals." t
Prof. Eraud, of Paris, praises it highly as a dressing in simple
wounds, in ulcers, and as an injection in gonorrhoea; also the powder
as a dry dressing. He finds it to cause neither irritation nor pain. J
"As a soluble non-toxic astringent, strongly penetrating and antiseptic,
it seems to deserve a place. Excellent results have also been obtained
by using solutions of ^ to 5 per cent, in laryngitis and pharyngitis.
Dr. A. Spengler, of Heidelberg, considers alumnol quite equal to zinc
chloride, while it has the advantage of not being unpleasant to use."§
Hydronaphthol seems to be /3-tetrahydro-naphthol, CjqHjjO, obtained
by the reduction of /3-naphthol by sodium. It forms white shining
crystals with an odour something like creosote, slightly soluble in
water, easily in spirit. Dr. Bryce recommends the external use of
1 part of hydronaphthol dissolved in 10 parts of rectified spirit, to
* Helbing, loc. r'U. t Heintz and Liebrccht, Pharm. Centraihalle, 1892, p. 697.
X Chem. and Drug., Jan. 21, 1893. § Lancet, April 21, 1894.
180 DISINFECTION AND DISINFECTANTS,
■which sufficient glycerine is added to make a 1 per cent, solution.
"In this form the antiseptic properties are well marked." Dockrell
has used it very successfully in a plaster against 7'inea tonsurans.
Mr. M. Clarke found it of great value in enteric fever and diarrhoea.
He says that it has a very distinct retarding effect on digestion, but
does not much interfere with that of milk.
Hydronaphthol gauze 5 per cent, is recommended as very lasting,
and as compatible with albuminous fluids.*
a-Hydroxynaphthoic Acid, called also simply oxynaphthoic acid,
CiQHg(OH).COOH, is formed by the action of carbonic acid on sodium-
naphthol. It melts at 186° C, is sparingly soluble in water, but easily
•in alcohol, ether, and the alkalies.
Collodion impregnated with ^ per cent, of it has been used as a
substitute for iodoform-collodion, as it is non-irritant and more stable.!
EUenberger and Meister established its bactericidal properties. A
5 per cent, ointment is antiseptic in scabies. Its salts are not antiseptic.
It has not been determined whether it is completely innocuous. |
" CMoronaphthalene" and "naphtholeum" are used for disinfecting
excreta in one of the London districts.
CHAPTER IX.
ORGANIC SUBSTANCES (continued).
Nitre-Compounds : Nitro-Benzene — Nitro- Phenols — Trinitio Phenol or Picric
Acid ; its value as an insecticide — Nitro-Cresols — Nitro- Glycerine —
Nitro-Cellulose — Collodion. Amido-Compounds : Ammonia — Compound
Ammonias or Amines — Amides — Amido- Acids — Imido-Compoiinds —
Hydroxylamine — Hydrazine — Methylamine — Dimethylamine — Trimethy-
lamine — Propylamine — Amylamine — The " Amines Process" — Aminol —
Aniline — Acetanilide or Antifebrin — Aniline Dyes as Antiseplics — Methyl'
Violets — " Pyoctanin " — Researches on their Antiseptic power- Apyonin.
Pyrrol- Compounds : Furfurane — Thiophene — Pyrrol — Jodol or Tetia-Iodo-
Tyrrol—Antipyrin or Phenazone— Salipyrin, &c. Pyridine Group, &c. :
Conine — Piperine — Pyridine — Antiseptic properties of Tobacco-smoke —
Nicotine — Various Patents as to Pyridine, &c. — Indole — Tryosine —
Quinoline or Leucoline — Diaphtherin — Loretin — Thalline — Quinine — Anti-
septol.
NITEO-COMPOUNDS.
The aromatic nitro-compounds are characterised by their poisonous
properties. Several of them have been suggested as disinfectants.
* S. W. Williams, Chem. and Drvg., 1893, p. 735. t Ibid., 1889, p. 34.
J i/bum. o/Soc. of Chem. Industry, 1888, p. 226.
ORGANIC SUBSTANCES. 181"
Nitro-Benzene (" Nitro-Benzol "), C8H5(N02), is a heavy yellowish
oil with an odour like bitter almonds. It is a disinfectant, because it-
kills bacteria, but its poisonous character and insolubility render it
unsuitable for general use. Pettenkofer and Lehmann* state that
the vapour of nitro-benzene " even in large quantities had no serious
effect;" but many aniline workers have experienced that it is
nauseating and narcotic. The same may be said of Nitro-Toluene,
CgH4(CH3)(N02)5 <fec., and the di- and tri-nitro-corapounds.
Ortho- and Para-Nitrophenols, CgH^(N02)0H, are obtained by
acting on phenol with nitric acid. Both are slightly soluble in
water, acid, germicide, and poisonous. Their sodium compounds are
soluble and antiseptic. There are no records of bacteriological experi-
ments with reference to them.
Trinitrophenol, "picric" or "carbolised acid," CgH2(N02)30H, is
easily produced by the action of nitric acid on nearly all organic
bodies that contain the benzene nucleus. It occurs in pale yellow
plates, and is very acid, little soluble in water (about l^ per cent.),
but soluble in alcohol. Its salts are yellow and explosive.
It is a very powerful germicide ; it almost immediately combines
with albuminoid substances, staining them yellow, precipitating the
albumens, and causing the death of protoplasm in exactly the same
way as iodine ; hence it is rapidly fatal to both bacteria and spores.
It does not, however, like iodine, permanently colour starch and
cellulose. The aqueous solutions are extremely poisonous, irritant,
but not corrosive.
Jalan de la Croix f found that bacteria in white of egg infusions
were killed by 1 in a 1,000 of picric acid, but resisted 1 in 5,000. He
also points out that a solution of 1 in 200 prevents growth in bouillon,
while i to 1 per cent, was required to destroy the germs ; this would
be a nearly saturated solution in water. Cheron I disinfected the
latrines of a hospital by the use of 10 litres of a saturated solution,
(li per cent.). He found that it arrested fermentation, and the
action of diastase and synaptase. The germination of seeds was also
prevented. It hindered the ammoniacal change in urine, even in
cases of vesical catarrh, when given to a patient, or injected into the
bladder.
Schwartz asserted (1880) that a minimum dose of 1 in 15,000 of
l)icric acid killed the bacteria of tobacco infusions transferred to
Pasteur's solution, whereas Kuhn maintained that 1 in 1,000 was
necessary, thus agreeing with Jalan de la Croix.
Picric acid is used in histology for hardening and preserving tissues.
* Acad. d. Wiaaeiuch. zu Afiinchen, 1887, p. 179.
t Arch./, exp. Pathol., Jan. 27, 1881. t J. eU Thirapeu'., Gnbler, 1880, p. 121.
182 DISINFECTION AND DISINFECTANTS.
Vallin states * that 60 centigrammes per day produce in man, besides
a deep orange colouration of the skin and urine, a slowing and
weakening of the heart, prostration of sti*ength, vertigo, and stupe-
faction,
Kinloch has recently patented picric acid as " an insecticide," anti-
septic and disinfectant.!
Except as an insecticide, when its staining powers and poisonous
action on plants and animals would be against its use, picric acid may
be pronounced to be unsatisfactory for disinfection. There is still,
however, a possibility of its being of special service in killing those
micro-organisms that only mercuric chloride will touch, as Klein
has shown, with some difficulty. Further experiments would be
desirable.
Potassium Dinitro-Ortho-Cresol, OgHo(N02)2(OH3)OK, occurs in
yellow needles, inodorous, sparingly soluble in water, poisonous, and
explosive by heat. Therefore, it is used as a yellowish paste, mixed
with soap and glycerine, and thus dissolves easily in water. It has
been lately introduced into this country under the name of " Anti-
nonnin " (F. Bayer & Co., Elberfeld). " Properly diluted it forms an
efficacious and safe insecticide, and does not injure plants. Though
originally intended to destroy certain kinds of caterpillars it has been
found to be fatal to mice, ants, snails, and all kinds of plant-lice, as
well as protecting wood from dry rot and fungi. 1 kilo, of antinonnin
in 300 litres is found most effective for killing lower plant life and
fungi. House and field mice succumb to three-twentieths of a grain,
best mixed with flour-paste." | The specification states that " 1 in 400
of water kills all insects, also fungi which rot timber; it may even be
«ised more dilute if time be given. Soft soap, ^ part, increases the
power."
There are a large number of other nitro-compounds of the aromatic
group, of similar properties, but of no special interest.
Nitroglycerine, 03115(0.1^02)3, is said to be antiseptic when dissolved
in alcohol and poured into water.
Nitrocellulose dissolved in ether or acetone is used under the name
of Collodion for protecting wounds, &c. Being insoluble in water and
the blood fluids, it has no antiseptic power.
AMIDO-COMPOUNDS.
Ammonia, NH3, has been described among the alkalies (p. 109). It,
like the other products of putrefaction, is fatal to the bacteria which
produce it, and the bactericidal power of ammonia, sulphuretted
hydrogen, and even of carbonic acid no doubt materially assist in
* Disivfectants, p. 156. t Patent No. 6,243, 1894. t Patent No. 3,301, 1892.
ORGANIC SUBSTAKCES. 183
retarding natural decay. Animal matter placed in a 5 per cent,
solution of ammonia remains free from putrescence for a long period.
When added to gelatin in which putrefaction had been already set up,
& 5 per cent, solution caused the putrefaction to cease. In an atmo-
sphere impregnated with ammonium carbonate, meat can be kept for
six months, and at the end of the time remain unaltered.
In all these cases it is necessary that the material be kept closed,
or the ammonia would rapidly escape. On account of its alkalinity,
smell, and irritant action, it has not been much used. The fact that
its vapour, which is at first stimulant, soon becomes excessively de-
pressant, also militates against its use for rooms. The compound
ammonias, or amines, formed by replacing successively the atoms of
hydrogen in ammonia by basic organic radicles, have greater antiseptic
properties. Methylamine, NH2(CH3), the simplest of these amines, is
a gas ; others are more or less volatile liquids ; while the more compli-
cated organic bases, like the alkaloids, are white solids. They are all
alkaline, form salts with acids, and the volatile ones have an ammoniacal
odour. As a class they are poisonous, therefore they are antiseptic
and may be disinfectant. They absorb sulphuretted hydrogen, but of
course do not absorl^ ammonia.
The acid organic radicles, such as acetyl (CH3.CO), may also replace
the hydrogen in ammonia, forming a class of bodies called amides, e.g.^
a^etamide, CHg.CO.NHg, which are usually crystalline, neutral com-
pounds which are soluble in water and more or less volatile. A few,
like acetanilide, are antiseptic.
Hydroxylamine, NHgOH, has been tried by Bing and others in skin
diseases. It acts as a reducing agent and is a strong germicide.
Hydrazine or Diamine, NgH^, has been found by Loew and Buchner
to be powerfully poisonous to animal, vegetable, and bacterial life.
Methylamine, CH3NH2, is a gas with a strong alkaline reaction- It
is more basic and more soluble in water and in alcohol than ammonia.
Its odour is like that of herring-brine, in which it is contained. The
hydrochloride, (CH3)NH2.HC1, crystallises in deliquescent, very solu-
ble plates, which give off methylamine on treatment with potash.
The sulphate forms an alum, (CH3NH2)2H2S04, Al2(S04)3, 24H2O;
this is a powerful disinfectant, but has not been much used.
Dimethylamine, (CH3)2NH, occurs in guano and, in small quantities,
in pyroligneous acid. It resembles the preceding. Neither of them
seem to have met with any practical application.
Trimethylamine, (CH3)3N, is a very volatile, alkaline, and inflam-
mable liquid, extremely soluble in water and alcohol. It also has the
fishy and ammoniacal odour. It is obtained from herring-brine, and
is made in large quantities, with ammonia, dimethylamine, methyl
184 DISINFECTION AND DISINFECTANTS.
alcohol, and methyl cyanide, by distilling " vinasse," a residue of the
beet-sugar manufacture. The source is " Betaine," the internal anhy-
dride of trimethyl-amido-acetic acid, CH2.00.0.N'(CH3)3.
In Patent No. 16,242, 1888, H. Wollheim claims its use "for de-
stroying, in a very short time, the vitality of all germs and spores
which can produce disease." Its compounds with acids crystallise
well, and resemble the ammonia salts, but are more soluble in alcohol,
and are said to be poisonous.
The Ethyl- and Propyl- amines are similar, but of greater density and
higher boiling point. Propylamine, (C3H7^)NH2, is metameric with
trimethylamine, and resembles it.
Amylamine, (C5H^-)NH2, is contained in the products of destructive
distillation of animal matters, such as bone oil. It is a liquid smelling
like burnt feathers, is antiseptic, but seems to have no special advantage.
The Amines process for treating sewage consists in the utilisation
of herring-brine with lime. This liquid is a mixture of amines, with
trimethylamine predominating. Klein and others, who tested the
effluent bacteriologically, reported very favourably on the process,
asserting that the result was complete sterilisation, that 1 per cent.
of trimethylamine was sufficient, and that the operation was easy
and inexpensive. Objections were made by others on the score of
(1) the offensive odour of the precipitant; (2) its deterioration on
keeping ; (3) in the case of its application inland, the quantity of salt
that must be discharged into rivers ; (4) the danger of the effluent
being poisonous to river-fish (this is not proved of the small quantity
of trimethylamine that would remain as, being volatile, most of it
evaporates into the air) ; (5) the alkaline character of the clarified
water; and (6) the difficulty of procuring a sufficient supply of herring-
brine.
"Aminol" is the name given to the mixture of methylamines
obtained by distilling herring-brine with lime according to the patent
•mentioned above. It is a clear colourless liquid, alkaline and odorous
of the bases. It is permanent when kept tightly enclosed, but easily
loses strength when opened. Two solutions are applied : — " D "
(disinfecting) for general disinfecting purposes, is said to be a "perfect
deodoriser, non-poisonous, non-corrosive, and does not stain;" and
"R" (Remedial), for medicine and surgery, "efficient remedy in all
suppurative, phlegmonous, or fermentative disease processes."
Aniline, CgH5(NH2), amido-benzene, is now made on a large scale
by the reduction ot nitrobenzene by iron filings and acetic acid. The
residue, acetate of iron, is oxidised to "red liquor," ferric acetate,
and has been used in France as a disinfectant. Aniline also occurs
in bone-oil (p. 190).
ORGANIC SUBSTANCES. 185
It is an oily liquid, colourless when pure, but turning brown in air
and light, boiling at 184° C, but easily volatile with the vapour of
water. Its melting point is 0-8° C, and specific gravity 1'036. It is
soluble in 31 parts of water, very soluble in alcohol, <fec., and forms
soluble crystalline salts from which the base is again liberated by
potash, soda, or lime.
It is poisonous, and hence a germicide. It slowly volatilises at
ordinary temperatures, giving a vapour of oppressive tobacco-like
odour, which also kills bacteria, but does not easily affect their spores,
Pettenkofer and Lehmann assert* that 0-1 per cent, of aniline vapour
in air is dangerous to man and animals. From this fact, and the slow
rate at which it diffuses, its use for fumigation is negatived.
The salts are antiseptic, and, being acid, absorb ammonia and com-
pound ammonias, but not sulphuretted hydrogen. Angus Smith t
places aniline in his sixth class — i.e., as moderately antiseptic. Dr.
Fischer has shown that tubercular sputa mixed with ten times its
volume of aniline water, is completely disinfected in twenty-four hours.
This is equivalent to the action of a 5 per cent, carbolic acid. At the
present price of aniline, it seems to be a disinfectant which is worth
trying.
Substitution Products. — An immense number of these have been
obtained, aniline being much more easily acted upon than benzene.
They are generally antiseptic, but have hitherto not yielded any satis-
factory results for hygienic purposes, and are less soluble and volatile,
and often more poisonous than aniline itself.
Acetanilide, " antifebrin," or phenyl-acetamide, CgH5.NH(CO.CH3),
prepared by boiling aniline with glacial acetic acid for several days, is
a white crystalline and easily soluble powder. Its melting point is ll^**
(Ritsert), and boiling point 295°, Potash and acids slowly reconvert
it into acetic acid and aniline. In 3- to 8-grm, doses it is antipyretic
and analgesic in fevers ; externally it has been used as an antiseptic
for wounds, but 30 grains in twenty-four hours has been found to
produce poisonous symptoms. A special therapeutic commission! pro-
nounced it inferior to phenacetin and antipyrin (p. 189).
Para-brom-acetanilide, " asepsin," or " antisepsin,"
CeH4Br.NH(CO.CH3),
is said to be anodyne and antiseptic. This must not be confounded
with "aseptin."
Aniline Dyes as Antiseptics. — Several of these have long been known
to have the power of penetrating into living animal and vegetable
* Acad. d. WUsenach. zu Munchen, 1887, p. 179.
t DxHxnftctanU, Edin., 1869. % Brit. Med. Joum., 1894.
186 DISINFECTION AND DISINFECTANTS.
structures, different dyes selecting different parts and species ; there-
fore, they are widely employed for microscopic staining. Their action
occurs in extremely dilute solutions, and is out of all proportion to
their poisonous action on higher animals.
The effect is to lower the vitality of, and, finally, to kill the organ-
isms. Hence it became a matter of interest to see how far they could
he used as actual disinfectants.
Koch proved* that a number of the tar dyes were inhibitory to
tubercle and other bacilli, both in local and in internal application.
The Methyl Violets are mixtures of hexamethyl-rosaniline hydro-
■chloride —
[OeH,.N(OH3),]2
C'
06H4.N(CH3)2.C1,
virith the salts of penta- and tetra-methyl rosanilines. They occur in
amorphous, dark blue masses (the pure hexa-compound is in large
deep violet crystals), soluble in alcohol, sparingly in water, but gives
it an intense violet colour.
Professor Stilling, of Strasburg, has experimented on the disinfect-
ing power of methyl-violet, and has found that a paste made with
wheaten flour, with a 2 per 1,000 solution of methyl-violet added,
■does not turn sour, however long it is kept. Milk mixed with the
same quantity does not turn sour, butter and bacon soaked in a
stronger solution (1 in 500) and dried, become superficially stained,
but do not afterwards become rancid. Mucor stolonrfer was sown
upon rolls of bread, some of which were soaked in a 1 in 500 to 1 in
1,000 solution of the dye, and some in water only. On the latter a
growth appeared in twenty -four hours, whilst on the former none
could be noticed after fourteen days. He has given the name of
■" pyoctanin," from croog, pus, and xraog, stain, to methyl violet, and
says it can be had absolutely pure from the firm of E. Merck, of Darm-
stadt. " Certain auramines proved to be the next best, when used in
solutions of 1 in 4,000 to 1 in 1,000." f
Dr. C. Prioux J points out that solutions of pyoctanin and gentian
violet, 1 in 100 prevent the development of micro-organisms. Weaker
solutions (1 in 500, or even 1 in 2,000) arrest the cultures of typhoid
and Bacterium coli communis (the ordinary microbe of the intestines) ;
* Mittlieil. a. d. K. Gesundh., 1881, vol. i., p. 234.
t Lancet, 1890, vol. xi., p. 965.
X International J. of Microacopy and Nat. Science, vol. iii., part 18.
ORGANIC SUBSTANCES. 187
1 per cent, solutions of safranine (an orange-red dye containing at
least three " benzene rings ") have also been shown to hinder Eberth's
bacillus from developing.
Solutions of blue pyoctanin for general surgery, ointments, powders,
and dressings have been introduced.
Dr. Petersen found that these preparations were as effective as
those made with iodoform, without the unpleasant odour, and without
any bad effects or symptoms of poisoning. Dr. Wanscher strongly
recommended a 1 per cent, solution for ophthalmic use and in urethral
dischai'ges, as lessening local irritation. They have also been used for
nasal and other cavities of the body, to stop suppuration. Von
Mosetig treated malignant tumours by injections of methyl violet, and
believes that complete cure by this method is possible.
Yellow Pyoctanin is an " auramine," obtained by acting on dimethyl-
aniline with phosgene, and then by ammonia; its formula is
0[CgH4. N(CH3)2]2- NH. It is a para-derivative of benzophenone,
and is specially recommended for ophthalmic practice.
<< Apyonin" is said to be also an auramine, and is intended for the
same purpose as the last.
PYRROL COMPOUNDS.
There are other rings analogous to the benzene ring, but containing
4 or 5 atoms instead of 6. Those with 4 carbon atoms include these
three chief compounds : —
Furfurane. Pyrrol. Thiophene.
CH = CH. CH = OH, CH = OH
^0»
^NH
OH = CH/ OH = CH^ CH = CH
All three are tar products, are volatile, colourless liquids, with
antiseptic characters that have not been well studied.
Furfurane, C^H^O, is a mobile liquid with an odour like chloroform,
and boils at 32° 0. It appears to be present in pine-wood tar,
together with methyl-furfurane, or sylvane, C4H3(CHg)0, which boils
at 63° C.
Furfurol, C4H3(CO.H)0, is the corresponding aldehyde, and is
formed by the action of acids on sugar, bran, «fec. {Furfur, bran).
Thiophene, C^H^S, is found in commercial benzene, and smells like
it ; it boils at 84° 0. It is probably an insecticide if not a germicide.
It is insoluble in water, but soluble in oil of vitriol, forming a
sulphonic acid, 04H3S(S03H).
188
DISINFECTION AND DISINFECTANTS.
Pyrrol, C^H^(NH), is colourless, but becomes brown in air (like
most of these bodies). It boils at 133° C, has a specific gravity of
1*077 {Atiderson), a faint odour like chloroform, and a hot, burning
taste. It is insoluble in alkaline solutions, but is slowly dissolved by
acids. It is contained in coal tar, but is generally made from bone
oil. Alcoholic solutions of pyrrol precipitate mercuric chloride.
"lodol," tetra-iodo-pyrrol, C4l4(NH), is made by the action of iodine
and potash on pyrrol. It is a pale yellow, inodorous and tasteless,
crystalline powder, almost insoluble in water, soluble in 18 parts of
alcohol, 155 of glycerine, 1^ of ether, and in oils. It decomposes at
140° C. with violet vapours of iodine. It gives a black precipitate
with mercuric chloride (hence incompatible with it), and is decomposed
by hydrochloric acid, iodine being liberated. It is reputed to have
antiseptic properties, and is used for the same purposes as iodoform,
but has not the objectionable smell, and is not so poisonous, but
Riedlin says * that it has no action on cholera or any other bacteria.
" Antipyrin," OjiH;^2-^2^' — -^7 substituting a nitrogen atom for one
of the (CH)'" groups in pyrrol, the grouping known as pyrazol,
C3H3.N.NH, is obtained. A body of ketonic character called pyra-
zolone,
CH :N\
I > NH,
CH2.CO/
is an oxy derivative of this compound. From it phenyl -methyl -
l)yrazolone,
qCHg) : N \
I >N(C,H,);
CH2.C0 X
and phenyl -dimethyl -pyrazolone or "antipyrin"; abbreviated in the
British Pharmacopoeia to "phenazone" are obtained —
Pyrrol.
CH = CH
CH = CH'
sNH
Pyrazol.
CH = N
CH = CH'
Pyrazolone.
CH = N .
>NH
)NH
CH.,- CO
Phenyl-methyl-pyrazolone. Phenyl-dimethyl-pyrazolone (antipyrin).
C(CH3) = N ^ C(CH3) - N(CH3)^
>N(CeH,)
CH2 — CO^ CH — CO
* Archxv.f. Hyg., vol. vii., p. 309.
)N(CeH5)
ORGANIC SUBSTANCES.
189
L. Knorr's patent* heats phenyl-hydrazine, NH2.NH(OgH5), with
ethyl aceto-acetate, OH^(CO . CH3) . CO . 0(C2H5), when water and
alcohol are separated, and phenyl-methyl-pyrazolone formed ; methyl
iodide converts this into antipyrin.
Antipyrin, or "phenazone," crystallises in colonrless scales, neutral,
inodorous and slightly bitter, fairly soluble in water, alcohol, and
chloroform, less so (about 1 in 50) in ether. It dissolves in acids to
colourless solutions. Melting point, 113° C. It has been found
mixed with acetanilide (p. 185), which is much cheaper; but the
detection is easy, as, although the melting point of the latter is also
about 113°, a mixture of the two melts about 45° C. It is antipyretic
and antiseptic, also an anodyne for neuralgia and gout (see Antifebrin,
p. 185). Externally, it has found favour as an antiseptic lotion, and
as gauze. It is incompatible with tannin, many acids, ferric salts,
iodine, and a number of drugs.
Nitro- and " isonitroso "-antipyrin, " salipyrin " (a salicylate ),
*' iodantipyrin " or " iodpyrin," " resopyrin " (a compound with
resorcinol) have been prepared.
PYRIDINE GROUP, &c.
If, in the benzene ring, nitrogen be substituted for a CH group,
pyridine, C^H^N, is obtained. From naphthalene and anthracene,
similar nitrogen derivatives are formed : —
Benzene.
CH
/ ^^
CH CH
!l I
CH CH
CH
Pyridine.
CH
/ \
CH CH
CH
CH
N
/
CH
CH
Naphthalene.
CH CH
^ \ /' -^
C
li
c
\ / \ .<
CH CH
CH
CH
Quinolinc.
CH CH
/" \ / \
CH C CH
CH
C
CH
\
CH
CH
Anthracene.
CH CH
^ \ / \
CH
C
CH
C
C
C
\
CH
CH
\
\
CH
CH
CH
CH
CH
^
Acritline.
CH CH
s / \ / \
C C CH
CH
C
S / \
CH N
CH
^'
CH
Additive compounds, of which piperidine or hexahydro-pyridine,
CjHjqNH, and nicotine or hexahydro-dipyridy), (C5H4N)2Hg, are
examples, are also known. The radicles, methyl, ethyl, <J:c., can
* Liebig'a Annalen, voL cczxzviii., p. 137.
190
DISINFECTION AND DISINFECTANTS.
also replace the hydrogen atoms giving homologues of pyridine, which
exist with it in coal-tar, and in larger quantity in bone-oil. They
much resemble pyridine in properties, but rise in boiling point and
diminish in density as the number of carbon atoms increases, and are
more readily oxidised and attacked. The mono-, di-, tri-, tetra-, and
penta-methyl derivatives have been obtained by the fractional distilla-
tion of bone-oil, the fractions so procured being mixtures of isomerides,
■which it is impossible to separate by this method. They were dis-
covered by Anderson in 1846, and investigated also by Greville
Williams, Ladenburg, and others.
Table of the PyRiDiNE HoMOLoonEs.
Constitutional
Empirical
Boiling
Specific
Name. Formula.
Fonnula.
Point.
Gravity.
Pyridine,
CsHfiN
117° C.
•985
Picolines,
CsH4(CH3)N
CcH^N
135°
•961
Lutidines,
C5H3(CH3)jN
C7H9N
154-5°
•946
CoUidines,
CfiHalCHsJsN
CsHiiN
180°
•944
Parvolines,
CsHlCHs)*
C9H,3N
...
...
Caridines,
Cfi(CH3)5N
CioHuN
211°
...
Rubidine,
?C5(C2H5)(CH3)4N
C„HkN
230°
...
"Viridine,
?C5(C3H7)(CH3)4N
C12H19N
251°
...
Conine, OgH^^-^j ^^^ volatile alkaloid of hemlock (Conium macula-
turn), is normal-propyl-piperidine, C5H^qN(C3H-), (Ladenburg).
Piperine, from pepper, is peperyl-piperidine, OjHjqN - CjgHgOg,
related to pyridine through piperidine (ibid).
It will be noticed that aniline, CgH5(NH2), is metameric with the
picolines, 0^114(0113)1^, of which all the three possible isomerides have
been separated from bone-oil.
All these substances are more or less narcotic poisons ; hence, would
act as antiseptics, and, if in sufficient quantity, would kill bacteria.
It has been mentioned that Saprol (p. 165) contains pyridine bases:
from most coal-tar disinfectants they have been removed together with
aniline by treatment with acids, but some of the newer preparations
contain appreciable quantities of these bases. The most important is —
Pyridine, O5H5N. — Wlien pure it is a mobile, colourless liquid,
which does not turn brown in air and light, and is slowly and com-
pletely volatile. Its odour is said to be " empyreumatic," but is most
persistent and unpleasant. It absorbs water from the air, and mixes
with it in all proportions ; it is also readily soluble in alcohol. It
forms soluble crystalline salts with acids. Oommercial ammonia often
contains pyridine, and commercial pyridine is sometimes contaminated
with ammonia.
OBOAMIG SUBSTANCES. 191
Tobacco-smoke, contrary to popular belief, does not contain nicotine,
■which is decomposed by the heat, but pyridine and its homologues,
and the beneficial efiect of tobacco in many cases of asthma, must be
attributed to these latter, whether as sedative or as bactericide (it
must be remembered that very little of the smoke itself gets into the
lungs). Pyridine inhalations have been proposed for asthma. "From
1 to 1| drachms are poured on a plate and placed in a rOom with the
patients. At 68° to 77° F. the above quantity evaporates in about an
hour. It is said that after a few minutes' exposure to the pyridine
atmosphere the remedy can be detected in the urine. The treatment
was well spoken of by Dr. Keleraen, among others, but does not seem
to have maintained its ground. Mixed with a little oil of peppermint-
it has been employed in the treatment of diphtheria with some
success, and in aqueous solution (1 in 300) three or four injections
have been recently said by Rademacher to be sufficient to cure
gonorrhoea." *
It was stated by the Cigar Manufacturers' Association of Hamburg^
that in the last visitation of cholera there were only eight cases and
four deaths amongst a body of 5,000 cigar-makers.
Dr. Burney, the senior Medical Officer of Greenwich Workhouse,
asserts that the to'bacco-smoking inmates enjoyed comparative im-
munity from epidemics, and tobacco-smoking is believed to have had
a disinfectant action in cases of cholera and other infectious diseases.
But Dr. Kerr points out that if a man canncrt stand smoking it may
depress his heart action and enfeeble his constitution, and so lessen
the resisting power to throw off the noxious germs. Pyridine fumi-
gations are also open to the same objection. It is recorded that
Tessinari found that tobacco-smoke, on being passed through tubes-
containing a nutrient gelatine and pathogenic germs for from ten te
thirty minutes, destroyed the bacilli of Asiatic cholera and of pneu-
monia. Pyridine was introduced by O. Fergusson as a horticultural
insecticide about 1890, but its odour was against it, although it was
most effective. Wynter Blyth exposed the yellow bacillus of nasal
catarrh, on threads, to the action of a 1 per cent, solution of a mixture
of pyridine, coUidine, lutidine, and acridine from bone-oil. After the
threads were washed and transferred to nutrient gelatine, there waa
no growth. In sour milk also, pyridine inhibited growth. Tobacco-
smoke passed through water killed the yellow bacillus. These experi-
ments tend to confirm the idea that disinfectant preparations containing
the basic constituents of coal tar are to be preferred to those only
containing the phenols, also that pyridine being very soluble in water
and non-irritant, might be of service in nasal affections.
• Helbing, Mod. Mat. Med., p. 65.
192 DISINFECTION AND DISINFECTANTS.
Nicotine, CjQH3(Hg)N'2, is an oily liquid which rapidly turns brown
in air. It boils at about 250° C, but is readily volatile with steam.
It has a well-known stupefying odour, is alkaline, dissolves easily in
water, alcohol, and ether, forms crystalline salts with acids, and is
extremely poisonous. Its use as an insecticide in gardening is familiar.
At Greenwich in 1893 the use of tobacco seemed to be protective in
an epidemic of English Cholera.
Nickels* covers the use of shale or bone-oil, or pyridine bases, with
resin and soda, as a disinfectant.
Overbeckf proposed the use of pyridine or leucoline (quinoline, see
below) with chalk or lime.
Indole, CgH^<^^-rT ^CH, crystallises in plates, moderately soluble
in water, easily in alcohol and ether, melting at 52° C, feebly basic,
having a peculiar fsecal odour, and giving a red colour or precipitate
of nitroso-indole with sodium nitrite and dilute sulphuric acid. It
readily volatilises with steam. As a product of putrefaction it has
been presumed to be antiseptic, but its odour would preclude its
practical use. It has derived a certain importance from the fact that
it is constantly formed in the growth of the bacillus of typhoid and
the spirillum of cholera. BujwidJ first proposed the "indole test,"
as given above, to distinguish these pathogenic organisms from others
that are innocuous. But unfortunately Bacillus coli communis, which
is commonly found in the intestines and in water contaminated with
normal fcEces. also forms indole, as might be expected from the latter
being always present in small quantity in the intestines.
Tyrosine, CgH4(0H).CHo(NH._,).C00H, iS-oxyphenol-amidopropionic
acid, is also a constant product of the putrefaction of albuminoid sub-
stances, and has been said to be strongly antiseptic. It crystallises
in minute needles, which are inodorous, almost tasteless, and nearly
neutral. It seems to be worthy of experiment.
QUINOLIN3 DERIVATIVES.
Quinoline, chinoline, or "leucoline," C,jIl7.N, is a colourless, highly
refracting, oily liquid of a disagreeably pungent and aromatic odour,
and a bitter acrid taste. In light and air it rapidly turns brown. It
melts below 4° C, boils at 237° C, and has a specific gravity of 1"081.
It dissolves sparingly in water, easily in alcohol, &c., to an alkaline
solution, and with acids forms soluble crystalline salts. The salicylate
and tartrate have been used in medicine, both internally and ex-
ternally. Quinoline occurs in coal-tar, &c., with two homologues,
• Patent No. 3,053, 1883. t Patent No. 3,199, 1883.
:;: Zeit.f. Hyj., 1887, vol. xL, p. 52.
ORGANIC SUBSTANCES. IDST
lepidine, CjoHgN, B.P. 265', and cryptidine OnH^iN, B.P. 274' C.
Quinoline is incompatible with oxidants, with iodine solutions, and
with metallic salts ; it is antiseptic, and is the subject of the following
patent* : — " It has been proved that quinoline and toluquinoline
possess great antibacterial properties, but the complete insolubility
of these substances in non-acid fluids presented a serious obstacle to
their use. This invention consists of using as a solvent soap in the
nascent state," as in creolin, &c., "50 kilos, of castor oil, 50 of quinoline,
by the clearing of the liquid, which is then diluted with 85 kilos, of
water," Quinoline does not saponify, so that the solution would
contain 20 per cent, of quinoline dissolved in aqueous soap, and would
become turbid with water like creolin.
" Diaphtherin " was introduced by Prof Emmerich and Kronacher,
of Munich,t who, after extended trials, pronounced it to be " equal, if
not superior, to previously known antiseptics." It is said to be di-oxy-
quinoline phenolsulphonate, 2C9H^(OH)N,06H4(OH).HSO3. {Ortho-
phenol-sulphonic acid, or "aseptol," p. 158.) It is a yellow powder,
readily soluble in water, decomposed by alkalies and even by blood,
with elimination of sparingly soluble oxyquinoline in a fine state of
division ; hence, whei;i applied to wounds, it does not lose its antiseptic
power as some phenolic substances do (it does not coagulate albumen).
Emmerich administered 0'25 gramme subcutaneously to guinea pigs,
without prejudicial results. "A 1 per cent, solution is sufficient for
antiseptic dressings."
a-Oxy-quinoline or carbostyrile, C9H^(0H)N, occurs in white
needles, melting at 198°, and is strongly antiseptic. It is the source
of:—
"Loretin," iodo-oxy-quinoline sulphonic acid, C9H5l(OH)N.HS03,
lately introduced as another substitute for iodoform, and reported on
by Prof Schinzinger, of Nuremberg. He showed that its action on
granulating and healing processes is a very favourable one, and is
superior to that of iodoform, while it is free from objectionable odour,
not toxic, and non-irritant, and rapidly removes any eczematous
tendency. It is also a good deodorant of purulent secretions and
decomposing tissues, "It is very beneficially employed to combat
external and parasitic diseases, and as an antiseptic may be blown
into cavities for internal affections."
Quinoline when reduced forms a tetrahydride, CgH^^N, which is
more strongly antiseptic than quinoline.
"Thalline" is para-methoxy-quinoline tetrahydride, C3Hio(OOH3)N.
According to the specifications (Skraup, 1885) it is made like quinoline,
• No. 18,913, 1S91 ; Lembach, Schleicher, and Wolff.
t Munch. Med. Wochemchr., 1890.
13
194 DISINFECTION AND DISINFECTANTS.
by heating methoxy-aniline (para-amido-anisol) with glycerine, sul-
phuric acid, and paranitro-anisol, &jid then reducing to the tetrahydro-
compound. It is an oily liquid, easily frozen, and then only re-melts
at 180°, with a strong odour like Tonka beans, and soluble in acids to
form crystalline salts. Ferric chloride produces an intense greea
colour, hence the name (da\}.6g, a green twig).
The sulphate and tartrate are found in commerce as yellowish-white
crystalline powders, soluble in about 7 and 10 parts of water, sparingly
in alcohol. They are acid, fragrant, and bitter, and darken in light.
In a paper by H. Schultz " On the InJBuence of Thalline Salts on
Putrefaction and Fermentation,"* he states that "0*5 per cent, of
thalline sulphate in sterilised gelatine prevented the further putre-
faction of meat. Yeast fermentation was considerably retarded by
1 per cent, of thalline tartrate ; with a less quantity, however, the
activity was increased," probably by supplying nitrogenous food to the
fungus. It must be observed that the agent would not answer for a
food-preservative, on account of its taste, odour, and physiological
action. Thalline was at first extolled as a substitute for quinine,
2 to 8 grains of sulphate or tartrate being given in aqueous solution,
but the salts are poisonous to the red blood corpuscles and act on the
nerve centres (Brouardel). As antiseptics they are still occasionally
used for injections (4 to 8 grains to the ounce) in gonorrhcea.
Quinine, CgoHg^NgO^jSHgO, appears to be a derivative of a partially
hydrogenised di-quinoline, and to have the formula
C9H6(OCH3)N - 09Hji(OH)N.CH3,
although it has not yet been synthesised. f Its action against fevers-
is probably as much due to its antiseptic power as to its effect on the
nervous system. The natives of Peru were in the habit of purifying
the water of fetid pools by throwing in logs of cinchona (Humboldt),
but the tannin would also take part in this treatment. Koch observes :
"The dose of quinine necessary to destroy the spirilla of relapsing
fever would be 12 to 16 grammes, which would kill the host as well
as the parasite." A much less dose is sufficient to restrain the
spirillum.
Antiseptol, iodo-sulphate of cinch onine, contains 50 per cent, of
iodine, and is said by Yvon J to be a powerful antiseptic for surgical
use. It must not be confounded with other antiseptics having a
similar name.
♦ Centr. Med. Wissensch., 1886, p. 113.
+ Liebig's Annalen, vol. cciv., p. 90.
+ Amer, Journ. of Pharm., Oct., 1890.
ORGANIC SUBSTANCES. ' 195
CHAPTER X.
ORGANIC COMPOUNDS {continued).
ACIDS DERIVED FROM BENZENE.
Benzoic Acid : Its Use as an Antiseptic — Benzo-boracic Acid, &c. — Benzoic-
Aldehyd, or Oil of Bitter Almonds — Sulpho-benzoic Acid — Benzosol — Benzo-
paracresol and Benzo-naphthol. Salicylic Acid : Its Three Isomerides —
Salicylates — Oil of Wintergreen — Salol — Salophen — Phenosalyl — Antiseptic
Value of Salicylic Acid — Patents — " Lactacidine " — The Use of Salicylic Acid
for Preserving Food — Objections — Tablets, Gauze, &c. — Anisic Acid —
Cinnamic Acid, Styracol — /3-Phenyl Propionic Acid — Phenyl Acetic Acid —
Gallic Acid — Tannin — Diphenj'l Derivatives — Styrone — Sodium Dithiosali-
cylate. Thymol, Camphors, and Essential Oils : The Terpenes, their
Properties and Products of Oxidation — Turpentines — Camphors — Thymol
Aristol — Europhene — Menthol — Oil of Cloves, Caraway, Hops, &c. — Terebene,
Oil of Eucalyptus — Camphor, Personal Use — Fatents—Eucalyptol — Eucalypto-
resorcin — Myrtol — Terpin Hydrate —Terpinol — Absynthol — Cary ophyllin —
Eugenol — Bomeol-^ Various Patents — Camphoid — Combining Disinfectants
with Soda Crystals — Bases of Powders — The Oxidising Power of Essential
Oils — Ozone Test — Sanitas, Sanitas Oil — Value of Sanit£is as a Disinfectant —
Camphoric Acid — "Pinol."
BENZOIC ACID GROUP.
Benzoic Acid, CgH^ . CO . OH, exists in gum benzoin, balsams of
Peru and Tolu, and several aromatic gums that have been used for
ages for enbalming. It is made by acting on boiling toluene,
CeH5(CH3), with chlorine, and oxidising the benzyl chloride,
CgHg. CHoCl, with nitric acid. It melts at 121° C, boils at 250° C,
but sublimes slowly with a pungent, aromatic odour, even at ordinary
temperatures. It is sparingly soluble in cold water, yielding an acid
solution of pungent, disagreeable taste. It acts as a stimulant,
expectorant, diuretic, and is strongly antiseptic both as solid, solution,
and vapour, and even in its salts.
Salkowski,* in a number of experiments with meat juice inoculated
with putrid fluid, showed that benzoic acid, in a dose smaller than
salicylic, prevented for a long time the putrefaction of the mixture
and the development of bacteria. Bucholtz t found that 1 in 1,000
stopped the growth of micro-organisms. Haberkorn did not succeed
* Ueher die antiaept. Wirkung d. Salicylmure und Benzoesdure, Berlin Klin.
Wochemchr., 1875, p. 22.
t Archiv.f. exp. Pathol., 1876, vol. iv.
196 DISINFECTION AND DISINFECTANTS.
with the bacteria of urine with less than 1 in 400. Jalan de la
Croix,* in seventy-four experiments with varying quantities, showed
that the least quantity that would prevent bacterial growth from
being inoculated into a fresh liquid (beef tea) was 1 in 2,800. To kill
bacteria he required 1 in 410, and to sterilise spores 1 in 50. As
regards non-organised ferments (" enzymes "), Wernitz f declares that
pepsin is neutralised by 1 in 200, and others by 1 in 300, of benzoic
acid or benzoate of soda.
Graham Brown j stated that sodium benzoate was superior to
quinine hydrochloride and sodium salicylate in destroying the virus
of diphtheria ; he believed even that by saturating the liuman system
with benzoic acid by repeated hypodermic injections, it was rendered
almost insusceptible of inoculation with diphtheria.
In disorders of the bladder, attended by ammoniacal urine, Gosselin
and Robin § proved that benzoic acid taken internally rendered the
urine acid, preventing the precipitation of insoluble phosphates, and
the formation of carbonate of ammonium and poisonous salts by the
urinary bacteria, and also diminished the amount of urea excreted.
Therefore, Frerichs introduced it successfully for uraemia. They use
1 to 4 grammes per day dissolved in glycerine and water.
Vallin states || that " in most cases, to destroy definitely and
without return germs transplanted from a sterilised liquid into the
midst of an appropriate culture fluid, the proportion of benzoic acid
should be 1 in 77, or even 1 in 50." This would make it rather more
potent than phenol, cresol, or other similar compounds. It is not
poisonous ; Prof Senator, of Berlin, gave as much as 50 grms. of
sodium benzoate a day to a patient with acute rheumatism, without ill
effect. As much as 1 oz. of ammonium benzoate per day can be taken
without any noticeable effect, and is excreted as hippuric acid in
the urine.
In those cases in which the odour and taste is immaterial, a
saturated solution of benzoic acid in water delays the putrefaction of
animal matters much more effectively than salicylic. It has less
effect on vegetable effusions. It is also useful for preventing fats
from becoming rancid. Added to milk, a very small quantity
prevents coagulation.lT
Benzoic acid and benzoates are ingredients in many antiseptic
mixtures, as, for example, the following complex receipt : — " Anti-
septic pastilles for use in diphtheria are made by incorporating boric
* Archiv. f. exp. Pathol,, 1881, vol. xiii., p. 175.
+ Dorpat Essay, 1880. + Kleb's Archiv., vol. viii., p. 140.
§ Arch. gerUrales de M6d., 1874, vol, xxiv., p. 566. || Disinfectants, p. 202.
IT Horn, Zeitachr.f. Chem. Industr., vol. ii., p. 329, 1888.
ORGANIC SUBSTANCES. 197
acid and borax, each 20 grms.; citric acid, 125 grms.; sodium benzoate,
1 grm., with glycerine and water as solvents, and gum, sugar, and
gelatine as bases, and dividing into 500 pastilles."* Dr. Miller states
that by using the following mixture he could completely sterilise the
mouth and cavities in carious teeth : — " Thymol 4 grains ; benzoic
acid, 45 grains ; tincture of eucalyptus, 3| drachms ; water, 25 ozs." f
By heating benzoic with boracic, tartaric, or citric acid, double com-
pound acids called benzo- boracic, «fec., are formed, which are, of course,
antiseptic, and are mentioned in some of the older patents.
Although the benzoic acid is thus rendered much more soluble, and
its taste is in great part disguised, it frequently crystallises out, and
hence these compounds are now seldom heard of This separation also
makes them irritant to wounds and mucous surfaces.
Listerine contains 2 grains of benzo-boracic acid in each fluid drachm,,
together with the essential oils of thyme, eucalyptus, BajHisia, Gaul-
tlieria, and Mentha arvensis.
Benzoic aldehyde, or benzaldehyd, CgHg. CO . H, occurs with hydro-
cyanic acid in oil of bitter almonds. Angus Smith % considered it a
little below phenol in antise{)tic power. It readily oxidises to benzoic
acid, is sparingly soluble (1 in 30), and is of no hygienic use except in
ointments, when the crude oil is very effective against eczema, irrita-
tion, and parasites, partly on account of the prussic acid it contains.
Obviously the skin must not be broken.
Sulphobenzoic acids, C^H4(HS03)(CO.OH), of which there are three
isomers, made by the action of oil of vitriol on benzoic acid, are very
soluble, and have an acid and bitter taste. They and their salts are
antiseptic.§ The derivative "Saccharin," benzoyl -sulphonicimide, is
also sometimes used as a preservative. It has the constitution,
c,h/ )nh.
The mixture of sodium salts are met with as an antiseptic under the
name of sodium sulphobenzoate.§
Benzanilide is a weak antiseptic used as an antifebrile.
"Benzosol," or benzoyl-guaiacol, (CgH5)CO.O(OgH4.0CH3), is obtained
Irom benzoyl chloride and sodium guaiacol. It is a crystalline powder,
colourless, almost free from taste and smell, insoluble in water, easily
soluble in alcohol, and melts at 50° C. It is said to combine the
effects of guaiacol (p. 175) and benzoic acid without any disadvantages,
and to be very useful in tuberculosis, facilitating expectoration and
* Year-Book of Pharmacy, 1889. t Chem. and Drug., 1887, p. 83.
t Disinfeclanta, Edinburgh, 1869. § Joum. Soc. Chem. hid., 1888, p. 226.
198 DISINFECTION AND DISINFECTANTS.
rendering the sputum free from bacilli. Prof Sahli, however, remarks
that the commercial article is of varying composition, that he found
some specimens inert, and that "as the effect of guaiacol and creosote
were due to local antiseptic action in the stomach, benzosol could not
take their place." It is used largely in diabetes mellitus.
Benzo-paracresol, CgH3(CgH5.CO)(CH3).OH, is an antiseptic prepared
by the action of sodium benzoate on paracresol (p. 164), in presence of
oxychloride of phosphorus. It occurs as a crystalline powder almost
insoluble in water, but soluble in alcohol (0-15 per cent.). It melts
at 71° C*
Benzo-naphthol, C^oH;O.CO{CgH5), from /3-napthol, melts at 110° C,
and has also been proposed for internal antisepsis.
SALICYLIC ACID.
There are three isomeric oxybenzoic acids, of which only the ortho-
compound, called salicylic acid, CgH4(0H).C00H, is of practical
importance. It is met with in minute white needles or prisms, of
pungent odour and sweet taste (inodorous when pure, Charteris),
soluble in 500 parts of cold, and 15 of boiling water, in 7 of alcohol,
3 of ether, and 50 of glycerine. When heated quickly it breaks up
into phenol, which distils, and carbonic acid. The same decom-
position occurs in the human system, as phenol appears in the urine.
It is antiseptic and antipyretic.
J. B. Duggan found that it was twice as powerful an antiseptic as
the corresponding para-oxy-benzoic acid, whilst the meta-acid had
intermediate properties,!
" Artificial " salicylic acid (from sodium phenate and carbonic acid)
is somewhat more toxic in its action than the pure " natural " acid
obtained from oil of wintergreen. This is due to two foreign acids,
isolated by Williams in 1878, and found by Dunstan and Blochj to be
ortho- and meta-cresotic acids, CgH3(CH3)(OH).COOH, derived from
the cresols contained in the crude phenol from which the salicylic
acid had been prepared. Schering and others now prepare a pure
artificial acid from pure phenol, which is free from these impurities,
and acts in the same way as the natural acid. It melts at 156*7° C.
It gives a purple colour with ferric salts, therefore cannot be pre-
scribed with them. It is not corrosive, and does not coagulate
albumen.
The salicylates are much more soluble. Salts of nearly every metal
have been prepared and recommended for various uses; but sodium
salicylate, CgH^(OH).COONa, is the most usual one.
* Eevue de Chim. Indtialr., April 15, 1893. t Am. Chem. Journ., vol, vii,, p. 62.
i Journ. Chem. Soc, April, 1891.
ORGANIC SUBSTANCES. 199
Oil of Wintergreen, GauUlieria procumhens, is methyl salicylate,
OgH^(OH)COO(CH3). It is a colourless, fragrant liquid, sparingly
soluble in water, but easily in alcohol, and also in alkalies. Specific
gravity, 1-18 ; boiling point, 222° C.
Perier, of the hospital of St. Antoine, Paris, substituted this oil
for phenol in surgery, using a mixture which was perfectly miscible
with water : — Oil of Wintergreen 30 grammes, tincture of quillaia
6 grammes, water 1 litre. Gosselin and Bergeron* found that the oil,
both as a solution and as vapour, hindered the putrefaction of blood,
and that it was neither irritant, nor of disagreeable odour. It is still
used in France for dressings, but is inferior to phenol and other agents
in power. It does not coagulate albumen, and is not poisonous.
"Salol," Phenyl salicylate, C!6H4(OH).COO(C6H5), is made from
sodium phenol and sodium salicylate by heating with phosphorus
oxychloride. It is a white crystalline powder, melting at 42° C,
with a fiiint aromatic odour, practically tasteless, neutral, insoluble
in cold water, soluble in 15 parts of rectified spirit, in 3 of ether,
and very soluble in chloroform and in oils. Antipyretic and anti-
septic, it passes through the stomach unchanged, to be decomposed
in the duodenum into phenol and salicylic acid.f It is used in
•diarrhoea, dysentery, cliolera, &c., as an internal antiseptic, also as
an injection in gonorrhoea and cystitis. It has been employed
externally as a substitute for iodoform in skin and nasal diseases.
Lowenthal + has shown that salol will kill cholera bacilli in a paste
■containing pancreatic juice. Spirituous solutions (5 per cent.) are
employed with various flavouring agents for mouth-washes and
•dentifrices, toilet-powders, and soaps. When melted with camphor,
salol, like many other substances, forms a permanent liquid which
has also been used to replace iodoform.§
"SalophcD," C^H^(OH)(COO.C6H^.NH.CO.CH3), an imido-com-
pound formed by heating salicylic acid with phosphorus oxychloride
and para-nitrophenol, reducing and acetylating, resembles the preceding
in properties, but is said to have rather stronger antiseptic power.
M. P. 188° 0. It has not been much used, and is expensive.
Cresyl Salicylates. — The three cresols form corresponding salicylates,
and have been proposed as internal antiseptics.
Betol, salinaphthol, or naphthosalol, is a j3-naphthol salicylate, and
has already been described under Napthol (p. 179).
Salbromanilide is said to be a mixture of bromacetanilide and sali-
cylanilide.
Salipyrin is a compound of antipyrin and salicylic acid.
* Arch, general, dt 2Idd., 1881, p. 16. + Brit. Med. Journ., 1887, vol. xi, p. 1438.
J Complea Bendus, vol. cvii., p. 1169. § Repertoire, 1889, p. 185.
200 DISIMFECTIOM AND DISINFECTANTS.
Phenosalyl is a mixture of phenol, salicylic, benzoic, and lactic acidf,
made by heating them together at 140° C, adding menthol and euca-
lyptol, and, after, cooling, adding four times the volume of glycerine.
It is a clear, syrupy liquid, of sweetish taste. It is easily miscible
with water or alcohol, is not poisonous, and has a pleasant and non-
persistent odour, which does not cling about the hands and clothes.
The solutions have no corrosive action on the skin, the mucous sur-
faces remain smooth and slippery, and do not become dried up, as is
the case after washing with carbolic acid or "corrosive sublimate."
Of course, this latter advantage belongs to the glycerine, and would
equally pertain to phenol or mercuric chloride in the same medium.
Prof. Frankel,* in a series of bacteriological trials, found that pheno-
salyl possessed an antiseptic power superior to phenol in dealing with
the micro-organisms of cholera, anthrax, pneumonia, typhus, diph-
theria, tuberculosis. Bacillus pyocyaneus, and Staphylococcus pyogenes
aureus. " It is well known that the last-mentioned bacterium is one
of the most resistant, but even a 1 per cent, solution of phenosalyl is
sufficient to kill it, while to produce the same effect with carbolic acid
one must use a 2| per cent, strength, and the exposure or contact
must be continued for a longer period." Phenosalyl has been used by
Duloroy in the sterilisation of instruments, of gauze, antl of different
organic substances like blood, as well as decomposing urine and the
saliva of consumptives with most encouraging results. It does not
corrode nor discolour metals under ordinary circumstances of contact.
This is an example of a mixture which seems to present great
advantages. Of late years there has been a tendency to use compli-
cated compounds, most of them only soluble in alcohol, which, apart
from expense and other faults, is inadmissible as a medium for many
purposes. It should be noticed that while in mixtures the properties
of the ingredients are mostly retained, in many of these compounds
not only are the properties lost, but frequently new and objectionable
ones are developed. For example, the desire to avoid the unpleasant
odour of iodoform has led to the introduction of many " substitutes "
which are costly, unstable, uncertain, and even dangerous in their
action.
However, phenosalyl may be reckoned as a convenient preparation
of the above aromatic acids dissolved in lactic acid and glycerine, and
scented with menthol and eucalyptus. The name is rather an unfor-
tunate one, as leading to a wrong idea of its composition.
Salicylic acid is by no means an innocent remedy. In fact it can
be a powerful poison, as it has a disintegrating action on the blood
corpuscles. The salts cause albuminuria, hence, must be irritating
* Baeterienkunde, Berlin, 1890.
OROAKIC SUBSTANCES. 201
to the kidneys, probably througli phenol being formed.* The acid,
in strong (alcoholic) solutions, or in ointments, is so caustic that it
is the basis of most of the popular cures for corns. t As to dilute
solutions, Dr. Bond, of Westminster Hospital, states that "when in
the country he has been in the habit of taking 10 grains daily for a
month without bad effect," obviously as an anti-iualarial. The official
dose of the acid is 5 to 30 grains. Dr. Brouardel has noticed daily
doses of 2 grammes to produce grave symptoms of intoxication and
poisoning. KolbeJ first drew attention to the antiseptic properties
of salicylic acid. He showed that it prevented the action of enzymes
(unorganised ferments), like diastase, emulsin, and that of mustard,
also gastric digestion, fermentation by yeast, ammoniacal fermentation
of urine, and the germination of heeds. H. A. Weber § and Leffman
and Beam || proved that a solution of 1 in 420 of salicylic acid, com-
pletely checked salivary and pancreatic digestion of starch, and that
even 1 in 840 had a marked depressing influence.
As to the strength required for killing bacteria, it has been
variously given by different observers. Ratimoff^ uses 1 in 400,
practically a saturated solution in water and a little spirit; Jalan
de la Croix,** 1 in 200 for milk, and more than 1 in 35 for germs
in meat juice ; Buchbltz,tt 1 in 362 ; and Kiihn, 1 in 200 for germs in
albumen solution. As to salicylate of soda, the necessary dose is
stated as 1 in 100 by Miquel, and 1 in 161 by Bucholtz.
Vallin II points out that "this action on ferments and microbes is
often only temporary ; the ferments and bacteria rapidly become used
to their new surroundings, and the generations that succeed resist
doses that had been fatal to their ancestors, and the work of fermenta-
tion goes on again at the end of a few days. Keubaur and Bechamp
have specially proved this curious phenomenon of the habituation of
ferments to progressive doses of phenol and salicylic acid. It follows,
that, to obtain a durable antiseptic effect, we must at frequent inter-
vals add new and increasing doses of the agent. For this reason, in
alcoholic beverages, which can only be preserved by the aid of salicylic
acid, the dose of this substance sometimes reaches as much as 1*5
grammes per litre. Even then experience has shown that poor wines
and ciders soon undergo fresh fermentation of acid or putrid character.
* See a paper by Dr. Squire on the " Physiology and Therapeutics of Salicylic
Acid," Lancet, Dec. 20, 1879.
t Whelpley, Chem. and Drug., Aug. 16, 1890.
+ J.Jur Pract. Chem., 1874, vol. x., p. 89.
§ Journ. of Amer. Chem. Soc, 1892, p. 4.
II Journ. Soc. Chem. Ind., 1888, p. 582.
IT Bied. CeutrcUblatt, vol. xiv., p. 360. ** Ardi. exp. Pathol., 1881.
tt Ibid., 1875. tX D4nn/cctinU, p. 182.
202 DISINFECTION AND DISINFECTANTS.
Salicylic acid, then, is a convenient antiseptic, but it gives no absolute
guarantee, and its power is limited.j'
The very sparing solubility of salicylic acid in water has led to a
variety of devices for increasing it. Alcohol is in many cases unsuit-
able ; glycerine only dissolves 2 per cent.; alkalies form salicylates,
■which, although soluble, have only about one-third the antiseptic
power of the free acid. Borax solution dissolves a large quantity of
salicylic acid, forming a loosely-combined crystalline compound, in-
odorous, neutral, and of little taste, called borosalicylate of soda. It
is much more soluble, and is more antiseptic than either of its com-
ponents (see under Boric Acid, p. 102).
OfFen and Moore,* " to prevent the second fermentation of yeast or
•other ferment when combined with wheat or other cereal for food,"
use 10 parts of salicylic acid, 3 of box'ic, and 4 of borax, dissolved and
mixed with the grain either whole or ground ; " yeast is then added,
And the dough baked as usual."
Lactacidine solution contains 2*65 per cent, lactic acid, and 0-35 per
•cent, salicylic acid, " to which other materials, such as sugar or
glycerine, may be added." It is used for preserving articles of food —
€.g., butter. It may be removed by washing before use.t
Salicylic acid is largely used for preventing loss of material, and
•consequent annoyance with fruit; 4 to 8 grains of the acid to the
pint or lb. prevent fermentation in saccharine liquids; and jams,
preserves, &c., can be kept for years. " As a preservative it is best
applied in process of preparation. It is advisable to gradually intro-
•duce it in the solid state into the boiling mass "(but it somewhat
readily volatilises with the vapour of water), "constantly stirring,
or the acid may be rubbed down with the fruit juice, and then added.
In any case the finished product ought not to show any white flocks."
Another mode is to pour over the cold uncooked fruit the cold
isalicylated juice of the same fruit, so that the fruit is entirely
covered. A cold juice may be made by pressing the fruit, adding
to every pound 15 grains of the acid, heating the juice, and allowing
to cooL In this way, cherries, plums, &c., can be preserved all the
winter uncooked, and are then suitable for pies. The last of the
above processes seems better than the others, since almost all the
salicylic acid can be removed by washing the fruit before cooking.
Salicylic acid is very largely used for perishable articles of food.
Many preparations, more particularly of salicylic and boric acids, are
sold as *' lard bleachers," and " fruit, wine, and cider preservatives."
Most authorities agree that it is a most objectionable preservative,
especially in milk which is destined for young children. Powdered
♦ Patent No. 16,592, 1887. t Orosjils, Patent No. 2,235, 1887.
ORGANIC SUBSTANCES. 20S
salicylic acid, that has been used for hams, fish, &c., is mostly washed
off, but when mixed with, or allowed to penetrate the food, chronic
dyspepsia and other symptoms would certainly be caused by the rela-
tively large quantities that would accumulate in the system. There
seems evidence to show that, like lead and arsenic, it has a cumulative
action. Vallin,* in an exhaustive discussion of this point, shows that
if a man consumes an average quantity of salicylated foods and drinks
as met with in France (he gives tables of the amount customarily
added to a number of foods) he would absorb per day 3 grammes of
salicylic acid. He observes that it is nefariously used to secure the
disposal of inferior articles that would not otherwise be saleable. In
1880 the French Committee of Public Hygiene, after the matter had
been fully reported upon by M. Dubrisay, passed, on Feb. 7, 1881, the
following edict which is still in force : —
" Ust interdite la vente de toute substance alimentaire, liquide ou
solide, contenant une quantite qudconque d'acide scdicylique ou d'un de
ses derives."
At the present day, food arriving at the city barriers, if it should
be adulterated, and especially with salicylic acid, is seized, and its
owner punished.
K. Portele says j that salicylic acid cannot be considered a success
as a preservative either for butter or milk, as it gives to them an
unpleasant sweetish odour, which increases until decomposition takes
place.
H. A. Weber J and Dr. H. Yogel § strongly condemn the practice
of adding preservatives to food, proving that it interferes with
digestion. Nessler observes that "salicylic acid is not a natural
constituent of any food, and its addition is a fraud on the quality."
He, with Vogel, Pasteur, and others, demanded that the addition
of any quantity of this acid to wine should be mentioned on the bottle.
The German Government seem to be yet undecided.
In England, although a few trifling increases of fine have followed
the finding of salicylic acid by public analysts in milk where there was
added water also, it seems to be recognised as a customary addition to
syrups and to "British wines." In a test case at the Great Marlow
Petty Sessions, a grocer was prosecuted for selling raspberry wine
adulterated with salicylic acid. For the defence two analysts swore
that salicylic acid " was absolutely necessary to preserve the wine,"
and that it was "quite innocuous." In the result the case was dis-
• DdsinfeclarUs, pp. 189 to 193.
t Landw. Versucha. Slat., vol. xxviL, p. 143.
XJoum. Amer. Chem. Soc, vol. xiv., pp. 4-14.
§ Deutsche Viert.f. (iff. Gea., 1880, p. 40-2,
204 DISINFECTION AND DISINFECTANTS.
missed. If wines be Ccarefully made, they can be sterilised without
any drug, and will keep for a reasoijable time after opening.
Among special salicylic acid pre])arations the following may be
noticed : —
Solution for Local Antisepsis.* — Water, 1,000; boric acid, 12; sali-
cylic acid, 2.
In Patent No. 15,564, 1887, Boake and others show that "sodium
sulphite dissolves one-sixth of its weight of salicylic acid ;" they pro-
pose to make such solutions with any^alkaline sulphites or bisulphites
for antiseptic purposes.
"Stroch's Antiseptic Paper." — Seep. 142,
Antiseptic Tablets. — " (1) For Thiersch's solution, much used in
many modern operations, Adolph Levy, of Brooklyn, N.Y., recommends
14 grains of ' resublimed ' salicylic acid and 84 grains of pure boric
acid, to be compressed into a tablet, which is dissolved when required
in 16 ounces of hot distilled water, f (2) Warner it Co. make pastilles
of sodium bicarbonate, biborate, benzoate, and salicylate, with menthol,
eucalyptol, and oil of wintergreen. One of the pastilles gives 2 ounces
of a solution to be applied as spray in nasal catarrh." " Strongly
deodorant as well as antiseptic." :j: (3) Sacker, 79 Fenchurch Street,
make tablets of similar composition, " to be each dissolved in two
quarts of water." §
Salicylated Gauze. — Gauze washed with soda to remove grease, then
in succession with water and acidulated water, then bleached by
chloride of lime and weak acid, and finally well washed with water
and dried. Next soaked in a solution of salicylic acid, 5-6 parts;
glycerine, 15; rectified spirit, 50; distilled water up to 100 parts;
drained, nearly dried by a current of sterilised warm air, rolled or
folded by machines previously made aseptic. The finished gauze is
packed in cylinders freshly lined with melted paraffin sterilised by
heat. The gauze is thus kept permanently slightly moist. || Contact
with iron must be avoided, or purple stains result.
Anisic Acid or para-oxymethyl-benzoic, C^H4(0CH.;)C00H, occurs
in colourless prisms, melting at 175° and distilling at 280° C. The
sodium salt was recommended by Curci in 1887 as antiseptic and
antipyretic, in doses of 15 grains. It was said to be analogous in
action to sodium salicylate, but without disturbing influence on
digestion.
Cinnamic Acid, C^-IIyCH :CH.COOH, also met with in prisms, is
* Carcano and Cesares, lievue de Chim. Indust,, April 15, 1893.
t Chem. and Drug., vol. xxxviii., 1891.
J Lancet, vol. xi., 1890. § Lancet, vol. xi., 1889, p. 174.
II Seward Williams, Chem. and Drug., May 27, 1893.
ORGANIC SUBSTANCES. 20ft
more soluble ; melts at 133°, boils at 290° C. It is somewhat strongly-
antiseptic.
Styracol or cinnamyl - guaiacol, O^Hs.CH : CH.COO(C^H4.0CH3),
occurs in needle crystals ; is said to be a strong antiseptic in catarrh
of the bladder and intestines, and in phthisis ; soluble in alcohol.*
/3-Phenyl-propionic Acid or hydrociunamic acid, C,iH5.CHo.CH2.COOH,
is formed in the decay of albuminous matter, and, like other similar
products, is a bactericide. It forms fine needles, moderately soluble,
melting at 47° and boiling at 280° C. Klein regards this and phenyl-
acetic acid, CqH,;.0H2,C00H (sparingly soluble pearly plates, melting
at 76°, boiling at 262°, strong odour of burning urine), as among the
strongest of disinfectants. Laws has studied the next acid in this
series (see p. 159).
Gallic Acid, trioxybenzoic, OgH2(OH)3,COOH, is astringent and
feebly antiseptic. It occurs in sparingly soluble inodorous needles.
Taimin, gallotannic acid, Cj^HjqO(),2H20, is an amorphous powder,
usually brownish, very soluble, and strongly astringent. It is well
known to precipitate gelatin, and to form a compound with skins which
is imputrescible (leather). It also coagulates albumen. Therefore it
is, in some sense, antiseptic, but Gosselin and Bergeron,t having added
to 2 grammes of fresh blood 8 drops of a 10 per cent, aqueous solution
of tannin, saw vibrios appear in the mixture on the fourth or fifth day —
that is to say, almost as soon as they would without any antiseptic.
Gubler and Bordier | state that a horse which for many days had
received doses of 20 grammes of tannin, remained with its blood un-
putrefied till the fifth day after death.
There are many varieties of tannins from many diflferent plants, but
none of them have even the power to preserve their own solutions.
Styrone forms silky white crystals of a sweet taste, and having an
odour like hyacinths. It is soluble in 12 parts of water, and easily
in alcohol. The saturated aqueous solution has been recently found
in America to be a perfect deodoriser of a foul ulcerated surface, and
to cause no irritation. As an antiseptic it is said to exceed thymol.
This explains the healing properties long attributed to tincture of
benzoin, of which liquid storax is a constituent.
S.CgH3(0H).C00H
Sodium Dithiosalicylate "No. 1," | .has only re-
S.0eH3(OH).COOH
cently been brought under notice as a powerful antiseptic. In a 15
per cent, solution the most resistant bacilli are easily destroyed in
from twelve to fifteen minutes. In a severe case of ozoena it efi*ected
• A. Haas, Sudd. Apoth. Zeit., 1891, p. 55. t Arch, de M^d., 1881, p. 16.
t Bull, de T/UrapeuL, 1873, vol. Ixxxiv., p. 265.
206 DISINFECTION AND DISINFECTANTS.
a complete cure in a relatively short time. In 2| to 5 per cent, solu-
tion this preparation is reported to have yielded most strikingly
beneficial results in the treatment of foot-and-mouth disease, in which
its further trial would seem to be very desirable.*
THYMOL, CAMPHORS, AND ESSENTIAL OILS.
From the time of the ancients it has been known that this class of
aromatic bodies had a prophylactic action against fevers, and were of
value in purifying air, and as insecticides. Precious woods were those
which contained essential oils, like sandal- wood and cedar ; they were
used in constructions wished to be imperishable, and for boxes to
contain valuable tissues and documents. They were burnt for fumiga-
tions to drive away diseases, they were carried about the person, they
were thrown as logs into water, and mixed in wines and possets. The
ancient classic wines had generally a strong resinous flavour, due to
the admixture of herbs, and even to a trace of wood-tar purposely
added to the grapes to check objectionable fermentation, also to
bitumen on the stoppers, so that, apart from the agreeable odour,
there was also a real sanitary use for perfumes. A large number of
patents for disinfection contain aromatic gums and resins as adjuncts.
It is well known that these were used with bitumen for embalming,
and bodies have been preserved in this way. The result, however,
was in great part due to desiccation and protection from the air.
Musk, which seemed to give some relief in plague cases at Hong
Kong, has been successfully used in large doses for cholera by
Monsiorski.f
These odorous principles are divided into two classes : —
Class I. — Hydrocarbons, composed of carbon and hydrogen "only.
They mostly belong to the terpene groiip, CjqHjq, or derivatives of it.
This formula includes the liquid portions of the oils of thyme, orange,
lemon, savine, turpentine, juniper, hop, cloves, camomile, and the
majority of others. It will be noticed that the use of condiments may
be explained on the assumption that they are all (including salt,
mustard, and vinegar) antiseptic and preventive of fermentation,
hence germs in the alimentary canal have their action arrested. Oils
of capivi and cubebs, probably affecting micro-organisms in the urinary
tract, have the polymeric formula, CJ5H24, as proved by their vapour
density. Cedrene, from cedar, is said to be Cj^jHgQ, hence would not
be a terpene. Menthene from peppermint is C^oH^g. The cause of
the differences in odour of these different compounds of the same
formula is not yet entirely known, but in many cases the difference
is due to physical isomerism. All are liquids with boiling points much
•Helbing, Med. Materia Medica, p. 90. i Prov. Med. Journ., Feb., 1S94.
ORGANIC SUBSTANCES. 207
higher than that of -water (mostly 160° to 180° C), yet they emit at
ordinary temperature minute quantities of strongly scented vapour^
and are readily volatilised with steam. Their specific gravity is
usually less than that of water (0"83, orange, to 0*94, caraway), and
they are almost insoluble in it ; they are readily soluble in alcohol^
forming " essences," and in other hydrocarbons and in fatty oils.
When fragrant plants are distilled with water the essential oils float
on the surface of the distillate, while a small proportion dissolves to-
form the "distilled waters" of pharmacy, all of which are mildly
antiseptic.
Both the essential and the fatty oils produce a greasy spot on paper^
but the spot produced by the former gradually disappears, whereas-
that of the latter remains fixed, so that the presence of adulteration
can be easily detected.
The essential oils neither combine with, nor dissolve in, alkalies ;.
yet, if they be present when resins or fat are saponified, a large propor-
tion remains dissolved in the soap, and is only liberated on dilution
with water, when an emulsion similar to those obtained with tar
oils is formed.
Chlorine, bromine, and iodine act on most of the essential oils,
(iodine at first merely dissolves), giving compounds in which the
halogen displaces one or more atoms of hydrogen, at the same time
the odour is much afiected, becoming gradually pungent. Excess of
chlorine breaks them up entirely into hydrochloric acid and carbon.
Therefore they are not suitable for use with the halogens. The
antiseptic or disinfectant properties of substituted essential oils are
not well known, but there is no evidence to indicate their utility.
The terpenes rapidly absorb dry hydrochloric acid gas, yielding
compounds called artificial camphors ; some of them are crystalline,
and in appearance and properties much resemble natural camphors.
Patents have been taken out for these products, but they have not
hitherto been of much value. The artificial camphor obtained from
oil of turpentine is the best known.
Artificial camphors are only formed from the terpenes by slow
combination with water.
Turpentines. — When an incision is made in a pine tree, a resinous
fluid flows out, which is mainly a solution of various resins in the
hydrocarbon, O^qH^q, called "oil or essence of turpentine." " Common
turpentine " comes chiefly from Finns ahies, " Venice turpentine "
and " Bordeaux turpentine " from Pinus maritima, and " Chian
turpentine" from Pistacia lentiscus. They are somewhat different
in antiseptic value, but different specimens vary among themselves.
By distillation with water, about one-fourth (the essence) passes
208 DISINFECTION AND DISINFECTANTS.
over with the steam, while three-fourths remain behind as rosin.
The latter has no antiseptic power, but is used as an adjunct or
medium in a large number of organic disinfectants (J eyes, &c.).
"Camphine" is the oil of turpentine from Finns australis. Letheby
found that 1 in 4,000 of oil of turpentine in air prevented necrosis.
Class II. — Oxidised Compounds, such as camphor, thymol, ikc, are
crystalline solids, existing dissolved in the natural oil, from which
they either separate spontaneously or by refrigeration. They were
formerly called stearoptenes. Some of them have been formed by
oxidation of the hydrocarbons, others are of a different constitution,
such as —
Thymol, propyl-m ethyl-phenol, or propyl-metacresol, CgH3(CH3)
(C3lI-)0H. By cooling oil of thyme, crystals of thymol separate,
while the liqiaid portion consists of thymene, CjoH^g, boiling at
165° C. Oil of thyme contains about equal proportions of thymol
and thymene ; both have the pleasant odour of the plant and a hot
aromatic taste.
Thymol is easily fusible (melting point, 44° C), lighter than water,
in which it is very sparingly soluble (3 parts in 1,000), and is easily
soluble in alcohol. It does not readily combine with, or dissolve in,
alkalies, and is insoluble in acids, except sulphuric, with which it
unites to form thymolsulphonic acid, in almost inodorous soluble
crystals whose physiological properties do not seem to have been
•examined.
Dr. Paquet first* recommended thymol as an antiseptic in surgical
dressings, and as an inhalation in pulmonary gangrene. Jalan de la
Croix t found on an average that while 1 in 1,000 prevented bacteria
from growing, 1 in 100 was necessary to kill them, and as much as
1 in 20 to destroy the germs. Miquel ranks it as strongly antiseptic,
since 2 grammes " neutralised " a litre of beef tea. Other observers
found the following strengths necessary to prevent the development of
bacteria ; in urine, 1 in 3,000 (Haberkorn) ; in infusion of peas, 1 in
3,027 (Kuhn) ; in tobacco infusion, 1 in 2,000 (Bucholtz). Wernitz
states that a saturated aqueous solution (3 in 1,000) arrests pancreatic
digestion. Kobert, Kohler, and Stern used it to preserve vaccine
lymph, as while it prevented it from putrefying, it only slightly
diminished its activity. Koch mentions it as specially inhibitory to
tubercle. EatimoffJ puts it fourth in his list of disinfectants,
arranged in order of potency (mercuric chloride, silver nitrate, iodine,
thymol), saying that " 1 in 35,000 killed putrefactive bacteria."
* Bull, gin^ral de Th^rapeutique, 1868.
+ Archiv.f. experim. Pathol., Jan. 20, 1881.
t Bierdermann'a Cenlralblatt, vol. xiv., p. 360.
ORGANIC SUBSTANCES. 209
Thymol in a saturated solution in water arrests fermentation and
putrefaction better than carbolic or salicylic acids.* Thymol gauze is
used in surgery, and an ointment has been made with lanoline. It is,
however, too expensive for use on the large scale.
" Listerine " is a mixture of the essential oils of thyme, eucalyptus,
Baptisia, Gatdtheria, and Mentha arvensis ; each fluid drachm also
contains 2 grains of refined and purified benzo-boracic acid.
The action of iodine on thymol is of interest. The action may be
represented as follows : —
C6HI(CH3)(CsHy)OH
2C6H3(CH8)(C3H7)OH + SIj = + 4HI
C6HI(CH3)(C3H7)OH
This compound is di-iodo-di-thymol, and is known commercially as
Aristol or Annidaliae. — It is a white solid, melting at 60° C, insoluble
in water, soluble easily in alcohol and ether. Like most iodine com-
pounds it turns brown on exposure to light and air, liberating iodine.
It is said to be strongly antiseptic.
Menthol — Oil of peppermint contains a hydrocarbon, menthene,
CjoHjg, boiling at 163° C, together with a white crystalline solid
obtained by cooling it, menthol, C^QH^gHgO. Menthol melts at 34° C,
and boils at 213° C. It smells of peppermint, and has antiseptic
properties.
Peppermint from very early ages has had an immense repute as an
arrester of fermentations. Several medical receipts for " plague water "
have peppermint as a basis. In a recent cholera scare there was a
strong demand both in Germany and England for peppermint herb,
and for the oil and water. W. L. Braddon f directs attention to the
antiseptic properties of oil of peppermint in diseases in which antisepsis
is the best mode of treatment. Angus Smith spoke highly of it.:}:
It was ascertained by Koch that 1 part of the oil in 300,000 arrested
the development of spores, and that the vapour from warm oil of
peppermint quickly killed both spores and bacilli. Dr. A. Macdonald
found that the power of menthol is about double that of phenol —
*' 1 in 500 kills bacteria." § Both it and oil of thyme seem to be useful
antiseptics.
Oil of Cloves. — This is extensively used for preserving paste, gum,
•kc, and for carious teeth ("Bunter's Nervine"). It is heavier than
most essential oils (specific gravity 0"918), rather more soluble in
water, and n»ore volatile (boiling point 143° C). All these peculi-
arities increase its value as an antiseptic. It consists chiefly of a
liquid terpene, CjQHjg, holding in solution eugenic acid, CjqHjjOj
* Brit. Med. Journ., 1875, vol. i., p. 680. t Year- Book of Pharmaq/, 1888.
::: Disin/ectanU and Dmn/ection, 1869. § Edin, Med. Journ., 1880. p. 121.
U
210 DISINFECTION AND DISINFECTANTS.
{Ettling), with an isomer eugenin, and a variety of camphor called
caryophyllin, CioHjgO.
(HI of Caraway is yet heavier (specific gravity 0*938). It contains a
hydrocarbon carvene, CjoHig, isomeric with thymol — specific gravity
0*953, boiling point 225° 0. (Voelcker). The latter yields with an
alkaline solution of ammonium sulphide a peculiar substance named
carvol hydrosulphide, (OjoHi40)2H2S, in yellowish crystals sparingly
soluble in alcohol, almost insoluble in water, but slowly decomposed
by it. It has an unpleasant odour, and is strongly antiseptic, but
hardly available on account of cost, insolubility, and poisonous char-
acter. Jalan de la Croix * states that 1 in 1,000 of carvol destroyed
the bacteria of tobacco infusion, while 1 in 360 was requii'ed for those
of urine.
Oil of Cinnamon is considered by Lucas Championniere to be
superior to even corrosive sublimate as an antiseptic. Oils of verbena
and geranium have similar properties.t
Essence of Hops is a powerful agent in checking fermentation,
hence its former universal use in brewing. It readily absorbs oxygen,
being converted into an acid resinous mass containing valerianic acid,
CjHj^.COOH. The main constituents are a terpene, CjqHjq, and
valerol, CgHjoO.
All the other essential oils are more or less antiseptic, but their
general use is negatived by (1) their cost; (2) sparing solubility;.
(3) their persistent odour, which becomes after a time insupportable ;
(4) their want of energy in terminating, as distinguished from re-
straining, putrefaction and fermentation changes ; (5) internally, their
injurious action on digestion. Their chief value, beyond that due to
their odours and flavours, consists in their general property of hinder-
ing fermentation in the alimentary canal. They are largely used
for mouth washes, tooth powders, &c.
Terebene, CjoHjg (specific gravity, 0-86; boiling point, 160° C), is a
liquid obtained by acting on turpentine with about one-twentieth of
its weight of oil of vitriol, and distilling. It has a strong odour re-
sembling that of thyme and pine- wood, oxidises Jess readily than
turpentine, and is only slightly soluble in water, but easily in alcohol
and oils. Some years ago it was extensively commended as a " disin-
fectant;" it has now almost fallen out of use except in "Terebene
Soap," which is a pleasant preparation of some antiseptic power, con-
taining 1 to 2 per cent, of terebene.
Prof. Maclean, of Netley, reported favourably on its use for surgical
and sanitary purposes.
Camphors. — These are oxidised essential oils.
♦ Archiv.f. exp. Pathol., Jan. 20, 1881. t liev. Thdrap., 1S93, p. 290.
ORGANIC SUBSTANCES. 211
Ordinary or Laurel Camphor, CioH^gO, is a white solid of specific
gravity -996. About 1 per cent, dissolves in water, communicating to
it, as " camphor water," its odour, Avith its stimulant and antiseptic
properties. It is very soluble in alcohol ; the tincture in moderate
doses is an irritant poison. Dr. Kubini in Naples used it largely in
cholera and diarrhoea.
Camphor has some repute as a personal prophylactic, but it is obvious
that there cannot be sufficient of the vapour to disinfect the air. It is
irritant to the skin. It burns with a luminous sooty flame ; but when
burnt, either alone or with spirit, the products of combustion contain
little or no camphor. Spirit lamps containing this and essential
oils in spirit have often been proposed for fumigation, but are
obviously of little value.
There are numerous inventions relating to camphor. " Sanoscent "
is a block disinfectant containing camphor, eucalyptus, pine-oil, " and
other germ-killers." The basis of most of the cakes or blocks commonly
met with is either naphthalene, paraffin, or plaster. " Hebden's Cam-
phortar" is camphor, eucalyptus, and tar distillates, similarly made
into blocks for lavatories, &c., and also recommended to be gra,ted
among clothes for insects (see under Naphiludene, p. 148).
A mixture of equal parts of camphor and animal (vegetable?)
charcoal is recommended by Barbocci for preventing the offensive odour
and removing the pain (T) of old excavated ulcers.*
Kylet has shown that camphor combines in molecular proportions
with menthol. Symes % has made a similar compound with menthol.
These compounds, like that with phenol, are generally liquids. Hille§
suggests its use with magnesium or calcium chloride for drains and
for dressing vines.
Bromo- and iodo-camphor are strongly antiseptic, but irritant.
Eucalyptol, or eucalyptus camphor, O^QHjgO, was first isolated by
E. Jahns from the essential oil of various species of Eucalyptus.
Since then it has been detected in numerous other oils. Besides six
species of Eucalyptus there are 15 plants which yield it. It is a
colourless liquid, smelling like camphor, of specific gravity 0-930,
boiling point 176° C, and crystallising point — 1° 0. It is practically
insoluble in water, but is miscible with alcohol, ether, chloroform, and
fatty oils. The Eiccalyptus trees have long been famous for their
anti-malarial action, and are largely planted on the Continent in
marshy districts. According to Cloez, the half-dried leaves contain
€ per cent, of the oil. It is used in the antiseptic treatment of atonic
• Clien. and Drug., 1887, p. 373. i Am. Journ. Pharm., 1885, p. 429.
J Pharm. Journ., 3, vol. ix p. 598. § Patent No. 6,411, 1889.
212 DISINFECTIOX AND DISINFECTANTS.
ulcers, gangrene, (fee, internally and by inhalation for pulmonary
affections.*
Candles containing 5 to 10 per cent, of oil of eucalyptus or cajeput
with or without a little phenol were patented by "Wright. f In all
these fumigating appliances the greater part of the organic matter
is destroyed in burning, only a fraction being volatilised unchanged,
■while the peculiar odour becomes after a time sickly and insupport-
able. All fumigating candles, except the so-called "sulphur candles"
(p. 93) and some bromine and iodine forms (p. 73), are therefore
unsatisfactory. Tablets containing eucalyptus oil and chalk, which
have a powerful and pleasant odour, have been introduced for domestic
use. J
Eucalypto-resorcin is a hard amorphous mass obtained by mixing
eucalyptol with excess of resorcin in the cold. It crystallises from
chloroform, is insoluble in water, but very soluble in alcohol and in
ether. It is said to have some advantages as an antiseptic.
Myrtol, from essence of myrtle, is a clear liquid of pleasant odour,
boiling between 160° and 180° C. Eichorst recommended it as an
internal antiseptic. It is a mixture of dextro-pinene (the main hydro-
carbon of turpentine, juniper, eucalyptus, and sage oils, &c.) with
eucalyptol, and would be advisedly replaced by the latter (Jahns).
Terpin Hydrate, C^oHig(OH)o,H20, is prepared by the interaction of
a mixture of 4 parts of oil of turpentine, 3 parts rectified spirit, and
1 part of nitric acid in shallow porcelain dishes during some days. It
occurs in large colourless and inodorous crystals with a faint aromatic
taste. On warming there is a separation of the water and formation
of terpin, CjoHi8(OH)2. The development of tubercle bacilli is arrested
by a 0"25 per cent, solution (Colpi). It has been used internally in
lung and kidney diseases (^Manasse and Talamon).
" Terpineol " is the product obtained by boiling terpin or terpin
hydrate with dilute mineral acids. According to Wallach it is a
mixture in variable proportions of terpineol (CjoHjgO) and several
terpenes. Guelpa and Morra have proposed it as an antiseptic in
■cases of bronchitis.
Absynthol is an isomer of camphor from oil of wormwood.
Caryophyllin, CgoHg^Oo, is a polymer from oil of cloves ; Eugenol,
CjqHjjOo, an unsaturated compound, being the chief constituent of
the oil.
Bomeol or Borneo camphor, CjqHjjjO, from Dryohalanopa campliora,
* See Gimbertj Eucalyptus globulus, and its Importance in Agriculture, Hygiene,
and Medicine (Paris, Delahaye, 1870). Demarquay in 1872 recommended euca-
lyptol in surgery. Sir J. Lister has used it as a substitute for carbolic acid.
t Patent No. 11,963, 1884. X Lancet, vol. xi, 1890, p. 724.
ORGANIC SUBSTANCES. 21$:
is a white crystalline solid with an odour like pepper, resembling
ordinary camphor in properties. It is slightly more antiseptic than
camphor (Selmi).
An "Improved Disinfecting Fluid"* consists of 28 lbs. chloride of
lime, 14 lbs. of camphor, and 50 gallons of " black varnish" (a coal-tar
product) mixed together. "After standing for eight days the resulting
substance is ready for use in urinals, &c."
Camphoid, though in itself only feebly antiseptic, is a useful vehicle
for applying more active agents to the skin, and forms a protective
coating. It is a mixture of camphor, pyroxylin, and alcohol. Several
so-called disinfectant washing powders have been patented. These
usually consist of a mixture of disinfectants with soda crystals. R. P.
Hicks t makes a saturated solution of sodium carbonate in boiling
water, and then on cooling, as it crystallises, a mixture of diamylene
(or decylene, CjoHgo), cam])hene (one of the terpenes, C^oH^g), raenthene,
terebene, cymol, thymol, and sometimes phenol is added.
Many of the essential oils are used as disinfecting powders. Under
phenol (p. 154) the bases of the most common powders have already
been mentioned. Lime, magnesia, and alkaline bases unite with the
disinfectant when it has acid properties. The volatile oil is then
only slowly evolved by the action of the carbonic acid of the atmo-
sphere. Sand is too coarse for general use, but infusorial earth
and artificial silica (Calvert), being inert bases, give off the volatile
matters completely. For use in wet places, such as urinals, inorganic
bases are the best ; while for stables, rooms, «fec., sawdust and peat are
most serviceable. Plaster of Paris and cement are sometimes used ;
whilst dry earth and burnt clay are suitable for rough work.
The Oxidising Power of Essential Oils. — Sanitas. — Schonbein first
observed that in all slow processes of oxidation a small quantity of the
oxygen is converted into ozone. This is the case in the slow burning
of phosphorus. If any organic matters be present, they are rapidly
oxidised by the ozone formed. He remarked that oil of turpentine
and other essential oils were specially active in this way, and that
ozone, probably from being continually re-formed, was permanently
present in small amount as long as any oxygen was left.
He attributed the purifying action of perfumes entirely to this
ozonising effect. But Angus Smith J proved by experiments that the
explanation v.'as not suflacient, and that their antiseptic action must
also be taken into account. He suspended ozone paper (blotting-
paper dipped in potassium iodide and starch paste) in a large flask
containing a thin layer of the essential oil, and judged the amount of
* Lees, Patent No. 1,738, 1893. t Patent No. 6,209, 1887.
:;: Disinfectants, Edinburgh, 1869, p. 1 18.
214
DISINFECTION AND DISINFECTANTS.
ozone by the degree of blueing of the paper, taking 10 degrees as an
arbitrary maximum. He gives the following table : —
Degree of Blueing of the Ozone Paper.
-
After 18 hours.
24hotu^.
48 hours.
72 hours.
Oil of Orange-peel,
Considerable.
Strong Colour.
9
10
Essence of Turpentir
le. Feeble.
Distinct.
7
9
Oil of Juniper, .
Considerable.
91
5
5
„ Cumin, .
None.
None.
2
2-5
„ Lavender,
2
2-5
Cresol,
2
2
Phenol, pure, .
None.
1
Creosote (Wood),
,,
None.
Pyroligneous Acid,
,,
Camphor,
)>
Oil of Thyme, .
>>
Naphthalene, .
»»
This test is not very delicate, as there is no doubt that traces of
ozone are produced with all the above compounds except naphthalene.
Other observers have found oil of thyme to give more than cresol.
Yet the fact is obvious that the antiseptic action is not proportional
to the small quantity of ozone formed, though the slight disinfectant
power may be. Although, relatively, there is only a mere trace of
ozone, amounting perhaps to 1 in 1,000, nevertheless it may form a
considerable quantity in a large volume of air.
Scoutteten * found that ozonised air rapidly removed the odour of
foul manure ; Kichardson and Wood, that of putrid blood that had
been kept in a flask for two years. Bond attributed the disinfecting
action of permanganate to its production of ozone, f Boillet proved
that ozone not only destroyed a putrefactive odour already formed,
but actually prevented putrefaction. J Chapuis collected the germs
and dust from contaminated air by filtering it through cotton wool ;
he then submitted some of the wool plugs to the action of ozonised
air. On then placing the wool in a nutrient solution (wort), the
untreated plugs caused rapid turbidity and growth, the ozonised ones
remained clear for twenty days.§ From the known fact that the
hygienic condition of a locality varied with the proportion of ozone in
the air as shown by test papers, and that several epidemics liad been
preceded by a sudden fall in ozone, he very naturally argued that
ozone must have the power also of destroying pathogenic organisms.
Miquel asserts that ozone attacks gaseous emanations before it acts
• L'Ozone, Metz, 1856.
t Compies Rendus, 1875, p. 1258,
t Brit. Med. Joum., 1875, p. 239.
§ Bull. Soc. Chimique, 1881, p. 290.
ORGANIC SUBSTANCES. S15
on bacteria or spores. Subsequent investigations have sho\m that it
does attack the latter (see Ozone).
Thenard was one of the first to show, and Ireland,* Barlow,t and
others to confirm, that this gas is a poison, and was capable of causing
asphyxia and fatal bronchitis, and that even a very minute quantity
was irritant to the mucous membranes.
These facts have a direct bearing on the claim of many advertised
** disinfectants " to give ozone. The odour of turpentine, the smell
of a newly-painted house, even the proximity of a pine forest, though
supposed to be good for consumption and pulmonary complaints,
undoubtedly cause in many people considerable irritation of the eyes,
nose, and lungs. Still, in most cases, the freedom of the air from germs
produces manifest improvement.
C. T. Kingzett, about 1874, noticing that in presence of excess
of warm water, peroxide of hydrogen, which is not irritant, is produced
in solution rather than ozone, together with oxidation products of
the terpenes, which acted as strong antiseptics, introduced a new
disinfectant under the name of " Sanitas."
In the first patent | turpentine oil is floated to a sufficient depth
on the surface of warm water in large jars called oxidisers, and
•currents of warm air or oxygen are forced through the mixture
continuously for seven to ten days, maintaining the temperature con-
stantly at 60°. The proportions used are 9 parts of turpentine oil
to 1 of water.
Berthelot has also shown that oil of turpentine is capable of dissolving
from 3 to 5 per cent, of oxygen. The action in the presence of water
is, therefore, of a dual character, the atmospheric oxygen molecules
simultaneously producing molecules of peroxide of hydrogen, HoOg,
which dissolve in the water and oxidise the turpentine, yielding
camphors, camphoric acid resins, minute quantities of formic acid,
cymene, &c., and a substance named by Kingzett "camphoric peroxide."
Part of these dissolve in the water, part remain in the oil. The
products are : —
1. "Sanitas fluid," of a light straw colour and pleasant aromatic
odour. It contains camphoric acid, camphoric peroxide, and gives a
distinct purple reaction with sulphuric acid and potassium bichromate,
showing the presence of hydrogen peroxide, amounting, according to
the Lancet, to such a proportion that twice its volume of oxygen is
given off" when it is decomposed.
2. " Sanitas oil," a brown syrupy liquid, lighter than water, and
insoluble in it, but soluble in alcohol, and having a similar odour to
* AnncUe8 de ffygiine, vol. xir., p. 439. t Joum. of Anal, and Physiol., 1S79.
X No. 274, 1876.
216 DISINFECTION AND DISINFECTANTS.
that of the liquid. "When shaken with water, the latter acquires
a peroxide of hydrogen reaction which is not so strong as that
produced by the fluid.* It burns like camphor with a sooty flame.
Patent No. 5,572, 1882, added resin and resin oil, and camphor or
thymol. Turpentine, oil of eucalyptus, and " camphor oil " are also
among the ingredients used.
The " Sanitas air purifier " consists of fine wood flour impregnated
with camphoric peroxide. A Sanitas toilet soap is made, and soft
soaps, veterinary washes, and emulsions of the oil with gums, &c.
Patent No. 1,589, 1890 (Kingzett), refers to " oxidised turpentine mixed
with soft or hard soap." In patent No. 276, 1887, it is proposed
to use : —
1. Tin instead of earthenware for storing, as Sanitas is not corrosive
to metals.
2. Sea water instead of ordinary water, as the hydrogen peroxide
keeps better in a saline solution.
3. " One or more antiseptics added before or after oxidation."
Horgreavesf mixes Sanitas oil and other disinfectants with laundry
blue for linen.
Dr. A. B. Griffiths, in testing the germicidal powder of the various
Sanitas preparations, and particularly of "Sanitas oil" as liquid and
vapour, on the bacilli of diphtheria, tuberculosis, glanders, cholera,
typhoid, and scarlet fever, found that : —
1. "One-tenth per cent, of the oil was incapable of destroying the
microbe of typhoid in bouillon, but 1 per cent, prevented its develop-
ment."
2. "One-quarter per cent, completely destroyed Micrococcus scarlatlnce
in nutrient gelatine, ^ per cent, prevented its development (six tubes
in each case)."
3. "Eight tubes, each containing 100 c.c. of nutrient gelatine, were
inoculated with Bacillus diphtherice from pure sub-cultures of the
microbe; and after three weeks' incubation at 20° C, h c.c. of Sanitas
oil was added to each tube, and the incubation continued four days.
As a result, the microbes in all the tubes were found to have been
destroyed, as animals susceptible to diphtheria on being inoculated
were unaffected."
4. " The bacilli of tuberculosis and of glanders were destroyed
respectively by 1 per cent, in six, and by ^ per cent, in seven days."
5. " The spirilla of Asiatic cholera (Koch) in ten tubes of bouillon
(slightly alkaline) were killed in five days by 1 per cent, of the oil.
It was further demonstrated that it is quite impossible to inoculate
gelatine plate cultivations containing 1 per cent, of Sanitas oil with
* Lancet, vol. i., 1890, p. 809. t Patent No. 2,524, 1883.
ORGANIC SUBSTANCES. 217
the microbe of cholera ; although when Sanitas was absent the microbes
gave rise to colonies."
6. An apparatus was fitted by which the vapour of Sanitas oil from
a flask heated to 100° C. in a water bath was passed into test-tubes con-
taining nutrient media in which the above-mentioned organisms were
growing. They were all destroyed in from four to fifteen minutes.
From this it is concluded that the vapour itself possesses genuine
germicidal powers, and should be of service in the treatment of
diseases of the throat and lungs. It must be remembered, however,
that these are not quite the conditions under which the agent would
be employed in practice ; the bacterial growths seem to have been at
or near the surface of the nutrient gelatine, instead of having pene-
trated deeply into the tissues. No mention is made as to whether any
water was placed in the flask with the oil ; the vapour of a fluid with
so high a boiling point as Sanitas oil seems hardly likely to pass over
at the temperature of boiling water except in the presence of steam.
Dr. Bond, of Gloucester,* Dr. Poehl,t and Mr. Kingzett himself J
have placed "Sanitas" and its varieties in the very first rank of
disinfectants.
On the other hand, Vallin§ says that the statements should be
accepted with reserve, admitting, however, that " this product, being
unknown in France, we have not been able to experiment on its
efficacy." Harding Crowther|| points out that equal parts of vaccine
lymph and Sanitas fluid did not prevent the inoculation succeeding.
It might therefore be used as a preservative.
Tripe and Stevensonll and Longstafi" and Hare,** after numerous
experiments, arrived at the conclusion that " the Sanitas fluid and
powder do not disinfect better than slaked lime;" they recognise,
however, that this substance retards putrid decomposition, but that
"it is little active in deodorising substances already putrid."
It is obvious that Sanitas, like some other preparations, has sufiered
by being over extolled ; its chief points of interest are : —
1. The " fluid " is non-poisonous, non-corrosive, and does not stain.
2. It certainly oxidises most organisms and their products when in
sufficient quantity and strength, say 1 or 2 parts per 100.
3. In antiseptic power it is about equal to the cresol preparations
and superior to the carbolic ; over both it has the advantage, shared
* Brit. Med. Joum., 1876, p: 239. + Sevue d'hygiene, 1879, p. 510.
t Sanitary Record, 1879, p. 370, and 1880, p. 348.
§ Diainftctants, 1882, pp. 177 and 316. II Med. Times and Gaz., 1879, p. 361.
^ Med. Times and Oaz., 1880, p. 51, "Disinfectants in contradistinction to
Deodorants and Antiputrefactive agents."
♦• Sanitary Record, 1878, p. 353.
218 DISINFECTION AND DISINFECTANTS.
with permanganate and the halogens, of chemical destruction of the
microbes and of exhalations.
4. Its action on sulphuretted hydrogen is not great, that on ammonia
is almost 7iil. It can, however, be used with an absorbent like chloride
of zinc, but not with ferrous sulphate, sulphurous acid, or other re-
ducing agents.
5. Its price is decidedly higher than some other disinfectants if
quantity required be considered. A " Sanitas water-cart block, con-
sisting of Sanitas in a highly concentrated (solid) state," intended to
be placed inside the cart for disinfecting streets, has been proposed,
but it is more than doubtful whether this could be done efficiently
•except at a prohibitive cost.
6. It is valuable for toilet use when a persistent odour is not an
objection. Many people find it very agreeable. It ranks about equal
to sodium hypochlorite (liquor sodse chlorinata, p. 63).
7. More evidence as to its stability or constancy of composition is
required.
8. Further independent investigations as to its efficacy in epidemics
like typhus, cholera, &c., as to the poisonous dose of " Sanitas oil," and
whether it has irritant external effects, seem also desirable.
Kingzett calculates that the eucalyptus forests of New South "Wales
and South Australia alone contain, at any moment, sufficient oil in
the leaves, ready to be evaporated into the atmosphere under the
-agency of warm winds, to form no less than about 93 million tons of
peroxide of hydrogen, and 507 million tons of camphoraceous prin-
ciples.*
A fluid called " Pinol " is advertised, derived from Pinus pumilo. It
resembles other terpene preparations, but is somewhat more pleasant
in odour. We have no experience of its efficiency.
The Wandsworth Chemical Works manufacture "the Pineotas
series," including fluid, oil, sawdust, and soap, also carbolic prepar-
ations, sheep dips, &c.t
* Social Science Congress, Manchester, 1879 ; also see the same author's Nature''8
Hygiene,
t For further chemical information as to the terpenes and their derivatives, see
O. Wallach, Liebig's Annalen, vols, ccxxvii., ccxxx., ccxxxix., ccxlvi., &c., also
■on essential oils, &c., Journ. Soc. Chem. Ind., 1888, p. 226.
On cresols, Frankland and Ward's Second Report, abridged in Journ. Soc.
Chem. Lid., 1893, pp. 1,051-3.
On phenol and camphor in antiseptic dressings, see Gosselin and A. Bergeron,
Comptes Rendus, Sept 29, 1879, " Experiments on the Behaviour of Blood mixed
with known quantities of Phenol, Alcohol, and Camphorated Spirit."
COMPOUNDS RELATED TO THE ALCOHOLS. 219
CHAPTER XI.
COMPOUNDS RELATED TO THE ALCOHOLS.
Methyl Alcohol: Wood Spirit — Methyl Chloride — Chloroform — Methene Bi-
chloride. Formic Aldehyde or "Formalin": its Properties and Disinfectant
Value — Action on Bacteria — Other Aldehydes. Ethyl or Ordinary Alcohol :
Not a Reliable Antiseptic except when Concentrated — Higher Alcohols —
Acetone. Formic Acid and Sodium Formate. Acetic Acid : Aromatic
Vinegar — Acetic Acid as a Poison — Pyroligneous Acid — Acetates. Glycerine :
its Uses — Glycerine Soaps — Preservation of Food. Oleic Acid, Oils, and
Fats: Lanolin. Petroleum: Hexane — Vaseline. Vegetable Acids : Tartaric,
Citric, Malic, Oxalic, Succinic.
Methyl Alcohol, CH3.OH, is a colourless liquid closely resembling
ethyl alcohol, but boiling at a lower temperature, 66° C. In the
crude form of wood spirit it has long been used to preserve anatomical
specimens, owing its efficiency in great part to the creosote, &c., it
contains. It is fatal to insects and micro-organisms in the moderate
proportion of about 5 per cent., and were it not for its volatility and
the fact that its vapour when mixed with air is explosive as well as
narcotic, it would take a high rank as an antiseptic. Its relative
cheapness makes it a better vehicle for those aromatic antiseptics
which are insoluble in water than ethyl alcohol, which is commonly
used.
Tollens has devised a lamp for the slow combustion of methyl alcohol,
forming formaldehyde, and thus ensuring aerial disinfection.*
Methyl Chloride or monochlormethane, CH3CI, is a colourless gas of
sweetish odour, soluble in water, and neutral, compressible by a pres-
sure of 3 to 7 atmospheres into a colourless liquid, boiling at 21° C,
in which state it is sold in commerce in iron cylinders. Its vapour is
antiseptic, but no experiments are extant as to its relative value.
Methene or Methylene Dichloride, CHoCI^ (boiling point, 42° C), is
very similar to, but less powei'ful than, chloroform.
Chloroform, trichlor methane, CHCI3, has already been referred to
<p. 76).
Formic Aldehyde, Formaldehyde, or "Formalin," H.COH, is only
known in solution and in a state of vapour, since if an attempt be
made to condense it, it polymerises to a white crystalline solid called
para-formaldehyde, CgHgOg. Formaldehyde is readily soluble in water,
giving, if perfectly pure, a neutral solution ; commercially it is always
slightly acid, from the presence of a little formic acid. The odour is
* Ber. d. deutach. Chem. Gesells., 1895, vol. xxviii., p. 261.
220 DISINFECTION AND DISINFECTANTS.
very pungent, causing irritation to the eyes and nose. It is not a
poison. The aqueous solution is stable when kept in well-closed
bottles, but loses some of the gas on exposure. Loew and Fischer, in
1886,* discovered that it possessed powerful antiseptic properties;
Trillat, in 1888, showed that the presence of a minute quantity of this
substance in urine effectually preserved it from putrefying. In a
further paper he remarks that " hitherto it has been thought that the
most powerful antiseptic bodies belonged to the hydroxyl compounds
of the aromatic series of hydrocarbons (the phenols) and to the metallic
salts. Formaldehyde is, however, a very powerful antiseptic, being
actually superior to bichloride of mercury in this respect. The result
is quite unexpected, as acetic aldehyde does not possess this property."!
It is prepared by passing methyl alcohol vapour mixed with air over
a red hot platinum spiral or heated platinised asbestos, condensing
and purifying the vapours. |
Buchner,§ Aronsohn,]] and F. Cohnll have investigated the pro-
perties of formaldehyde, while Lehmanu, Gegner, and Blum** have
examined its value as a general disinfectant, and Stahl,tt Hauser,|| and
Liebreich S§ have reported on its suitability for special purposes. All
these writers are agreed in attributing to formaldehyde powerful anti-
septic and deodorant properties. Blum, however, points out that
micro-organisms are only killed in somewhat strong solutions (2 per
cent.). A recent paper by C. Slater and the author confirms Blum's
statements, jl II
With reference to the antiseptic power of formaldehyde, Trillat
states HIT that " the addition of 1 to 50,000 to meat extract had a
decided preservative action, while with 1 in 25,000 no change could
be noticed in the extract after the lapse of four days. Mercuric
chloride in these proportions has no effect, the extract showing change
in twenty-four hours. "With 1 in 12,000 the extract is kept good for
several weeks, while change occurs in five days when using an equal
weight of mercuric chloride. Several kinds of bacilli are destroyed by
a solution of 1 in 25,000, such as that of the saliva, &c." For the
preservation of meat, Trillat tried (1) immersion in the solution,
(2) exposure to the vapour, (3) wrapping the goods in coverings soaked
• Journ.f. praktische Chemie, vol. xxxiii., p. 221.
t Monileur ScienL, 1892, p. 490.
:{: Trillat and Berlioz, Compt. Rend., vol. cxiv.,p. 1,278 ; cxv., p. 290; cxix.,p. 563.
§ Munch. Med. Wochenschr., 1889, No. 20. |1 Berlin Klin. Woch., 1892, p. 749.
IT Botan. Centralblatt, 1894, p. 573. ** Munch. Med. Woch., 1893^ p. 32.
t+ Pharm. Zeit., 1893, p. 22. Jt Miinch. Med. Woch., 1893, pp. 567 and 655.
§§ Therap. Monatschrift, voL iv., p. 183. ||li Lancet, April 21, 1894.
HIT Moniteur Scientifque, 1892.
COMPOUNDS RELATED TO THE ALCOnOLS.
221
with the aldehyde solution. One hour's soaking in a 1 in 500 solu-
tion preserved the meat for twenty-five days; five minutes with a 1 in
250 solution kept it for twenty days, when exposed to air at 23° to
30° C. " The vapour was found to stop all decomposition, keeping
meat fresh for months and stopping fermentation in organic liquids."
Carabier and Brochet have shown that by heating dioxymethylene,
the vapour of formaldehyde produced effects the complete sterilisation
of household dust.*
Slater and Rideal's re-examination, f in which formaldehyde was
added to tubes of bouillon in proportions varying from 1 in 1,000 to
1 in 20,000, the tubes then inoculated with vigorous cultures of
different micro-organisms, and placed in an incubator, showed the
following results for inhibitory action : —
Proportion of
Formaldehyde
Proportion
Organism.
Inhibiting
Growth.
allowing some
Growth.
Remarks.
Staphylococcus pyogenes aureus,
lin 5,000
1 in 10,000
Growth poor — 1 in
10,000, and much
delayed 1 in 20,000.
Bacillus typhosus,
1 in 15,000
1 in 20,000
Very scanty growth.
,, coli communis.
lin 7,000
1 in 10,000
After seventy-two
hours' incubation.
„ atithracis.
1 in 15,000
1 in 20,000
Scanty growth on
sixth day.
Spirillum cholerce.
1 in 20,000
• ••
...
Bacillus mallei,
1 in 20,000
• ••
... ...
,, pyocyaneus.
1 in 7,000
1 in 10,000
On the third day.
„ lacticus, .
1 in 20,000
...
„ hutyricus (Hueppe),
1 in 20,000
..•
...
Micrococcus prodigiosus.
1 in 20,000
...
The authors remark, " This would place formaldehyde among the
first three or four antiseptics in Koch's tables. It is to be noticed
that even when the proportion is too small to prevent growth, the
cultures then obtained are scanty, and their development is long post-
poned. The fact that growth does not take place in the bouillon is
not proof that the microbe has been killed. Thus Bacillus mallei,
which showed no growth after four days' incubation in a 1 in 15,000
strength, when transferred to a fresh nutrient solution, gave rise to a
culture normal in all respects, except in requiring an unusually long
time to develop. Blum has shown with regard to anthrax that ex-
posure to the antiseptic does not cause attenuation." As to commercial
yeast, 1 in 2,500 of wort was required to prevent fermentation. In
lesser quantity the rapidity was diminished, but the final amount of
Compt. Rend., vol. cxix., p. 607.
-f Lancet, April 21, 1894.
222 DISINFECTION AND DISINFECTANTS.
alcohol was the same as if no antiseptic had been added. Hence
formaldehyde might be useful fo arrest secondary fermentations in
alcoholic liquids.
To determine the amount required to kill microbes, sterilised silk
threads were soaked in cultures of the various micro-organisms and
then transferred to the antiseptic. After exposure for various periods
the threads were withdrawn, well washed in sterile water, transferred
to bouillon tubes, and kept at 37° C. for more than eight days. The
tubes in which no growth took place were tested by inoculation in
order to determine whether they were still suitable for growth of the
microbes or whether the sterility was due to transferred antiseptic.
They all yielded copious growth on second inoculation. Control ex-
periments v/ere made in all cases. The results obtained were : —
" Time required to kill the microbes with a 1 per cent, solution.
S. pyogenes aureus, between 50 and 60 minutes ; B. typhosus, 40 to 50 ;
B. colt communis, 30 to 40; B. anthracis and S. cTwlerce, less than 15
minutes.
" With a 1 per 10,000 solution (threads examined every half hour,
at first, then hourly, then every twenty-four hours), B. anthracis (no
spores) killed in thirty minutes ; S. cholerce in two hours ; but putre-
faction organisms were not killed after twenty-four hours. Experi-
ments were made to see how far these solutions might replace the 1 or
2 per cent, solution of carbolic acid frequently used for the disinfection
of soiled linen before washing. Soiled clothes from the post-mortem,
room and sterilised clothes soaked in cultures were left for from twenty
to twenty-four hours in 1 per cent, and 1 per mille solutions of
formaldehyde. After washing in sterile water they were examined
by cultivation : —
1 per cent,
solution. 1 per 1,000.
Clothes from 2>os<-»iortem room, . . Sterile. Not Sterile.
Clothes soaked in B. typhosus, Spirillum
cholercB, or St. pyog. aureus, . . „ Sterile.
" The solutions are without any ill effect on clothes, and are efficient
as antiseptics, more especially the 1 per cent, solution, and the more
so as in practice the adherent formaldehyde solution would not be
removed." It seems especially suited for the disinfection of leather
goods and general articles, like combs and brushes, which cannot be
satisfactorily sterilised in other ways.
The action of the vapour evolved at 19° 0. from a 40 per cent,
solution was examined by exposing to it glass slips of dry bouillon
cultures under a bell-jar for ten minutes, B. typhosus and coli; M.
prodigiosus and Sp. cholerce were killed in less than ten minutes ; S.
pyogenes aureus in twenty ; B, pyocyaneus in thirty minutes. As to
COMPOUNDS RELATED TO THE ALCOHOLS. 223
the disinfection of rooms, 1| ounce of 40 per cent, formaldehyde was
evaporated by a spirit lamp in a room of 1,548 cubic feet (about 11^
feet side). The dust was disturbed by vigorous sweeping, then ex-
amined bacteriologically. After four hours' exposure to the vapour,
the dust was again disturbed, and a sample examined. In other
experiments threads soaked in various cultures were suspended at
different heights and at about 3 to 5 feet from the source of the
vapour. The results were not decisive, but showed decided eflfects of
the vapour. There is no reason why much larger quantities of the
antiseptic should not be used. The air before disinfection contained
429 organisms for 10 litres, afterwards only 71.
The threads after disinfection in all cases produced more scanty
cultures and more slowly. Some of those impregnated with B. typlwsus^
and coli were sterile.
It seems also to be possible to sterilise the skin with formalin, and
as it does not hinder the formation of a lather with soap, as mercuric:
chloride does, it seems a desirable substitute.
Trillat states that formaldehyde precipitates the tannin and colouring
matters of urine. It is also incompatible with ammonia, forming with
it a non-volatile crystalline compound. It is of course a reducing-
agent.
In commerce it is found as "Formalin," a solution in water con-
taining about 40 per cent, of formic aldehyde with a minute trace-
of formic acid, made by Schering of Berlin. A " formalin " dusting
powder is also available.
Berlioz and Trillat say that the vapour can be inhaled or injected
in throat and lung disease with marked benefit and without toxic
effects.* J. Stahl generally confirms the value of formaldehyde. f
Ethyl aldehyde and paraldehyde seem to be useless as antiseptics.
Chloral has properties similar to those of chloroform.
Alcohol, 02Hj(0H), coagulates albumen, hardens animal tissues^
and renders them imputrescible, hence it is used for preserving
anatomical specimens, bodies, <fec. For this purpose the old form of
** methylated spirit," containing 10 per cent, of crude wood spirit, is
better and cheaper. The new form, mixed with petroleum, is not
available, as it becomes turbid with water ; for other antiseptic
purposes, however, it is equally serviceable.
Bucholtz observed that a 1 in 30 solution of alcohol did not prevent
the development of vibrios. J Calvert and M'Dougall found that 1 in
20 prevented the putrefaction of beef-juice and egg-albumen for six
days. Wemitz established the fact that 1 in 3 to 1 in 10 destroyed
♦ Comptea Rendus, vol. cxv., p. 290. + Pharm. Zeit., 1893, p. 173.
+ Archiv.f. exp. Pathol., 1875, p. 159.
224 DISINFECTION AND DISINFECTANTS.
the activity of non-organised ferments (ptyalin, Sic.).* Jalan de la
Croix t found that it required a solution of 1 in 21 to prevent the
growth of adult bacteria transferred into bouillon, but the organisms
were not killed below 1 in 4*4, or 22 per cent., and the germs not
below 1 in 1-18, or 83 per cent. Meat broth freely exposed to air
remained free from bacteria when the proportion was 1 in 11, Gosselin
and Bergeron I exposed fresh blood in vessels covered with folds of
muslia to the vapour of strong spirit under a bell-jar. Putrefaction
was deferred to the eighth day by six drops of alcohol, whereas natur-
ally it would have appeared on the third or fourth day. Miquel's
statement is that " 95 parts of alcohol neutralised 1 litre of beef tea,"
about 10 per cent.§
It has been suggested that the gradual re-appearance of bacteria
when the solutions are exposed to air is due to the loss of strength
by evaporation of the alcohol. But Geissler has disproved this,
finding that open tubes containing a mixture of water and alcohol at
the end of seventy-two hours still contained 32 per cent, of alcohol,
the original amount having been 33 per cent. So that, as with other
antiseptics, the bacteria have the power of slowly becoming accustomed
to their environment. || With alcohol this toleration appears to be
very marked.
Alcohol, therefore, in itself is not a reliable antiseptic, although it
has been found useful for washing open wounds and even cavities.
Here of course its absorption and stimulant action must be taken into
account. With water, it is chiefly used as a vehicle for other com-
pounds, to whose efficacy it adds. Indeed, in some cases it probably
takes the principal part, the other materials, such as essential oils, ttc,
being in such small quantities as to act mainly as scents.
Dr. J. J. Ridge H describes the effect of minute quantities of alcohol
on cell protoplasm, and points out that it causes a shrinkage of the
protoplasm, by withdrawing water, slowly hardens and thickens the
walls and hinders nutrition.** To these phenomena must be attri-
buted its inhibitory action on bacteria, and its destruction even of
germs, when the solution is strong. Minute quantities have no action
in preventing putrefaction. Wines, for example, if of weak alcoliolic
strength, become sour, and even putrid. A mixture of acetic ether
and alcohol, with or without acetic acid, constitutes the antiseptic
and preserving agent called "Salubrine." ft
• Wirhung der Antiseptica, 1880. t Archiv. /. ezp. Pathol., 1881, p. 175.
t Arch, de MM., 1881, p. 16. § Org. viv. de I'Atmosph., 1883, p. 289.
II See Salicylic acid, p. 201 ; Watson Cheyne, Med. Times and Gaz., 1879,
p. 561.
IT Brit. Medical Association, 1890. ** Brit. Med. Journ., vol. i., 1891.
•H- Hakansson, Patent No. 10,465, 1893 ; J. S. C. I., 1894, p. 898.
COMPOUNDS RELATED TO THE ALCOHOLS. S2ff
Formic Acid, H.CO.OH, resembles its homologue acetic acid. Its
antiseptic power is less than that of acetic and propionic acid, and
according to Duggan,* in the series of fatty acids the antiseptic power
is proportional to the molecular weights. Sodium formate, H.COONa,
is a soluble salt resembling the acetate, but possessing reducing pro-
perties ; it has the advantage of dissolving many compounds which
are sparingly soluble in water alone, such as arsenious, boric, and
salicylic acids, and it does not favour the growth of moulds like
sodium acetate ; consequently it has been incidentally mentioned in
several patents, as, for example. No. 3,153, 1882, "Boric acid melted
with sodium phosphate and formate, can be cast into homogeneous
solid cakes, which are inodorous, very soluble and almost tasteless;
to be used by dipping or soaking to preserve provisions." It would
leave a white efflorescent crust, which ^ would undoubtedly be anti-
septic, and could easily be washed off.
Acetic Acid, CH3,C0(0H), in the pure state or "glacial," is a
crystalline solid melting at 17°, and boiling at 118° C; specific gravity
1*055. It has a strong pungent odour, and is very caustic. The
"strong acetic acid" of the British Pharmacopoeia contains about
30 per cent, of real acid ; vinegar from 3 to 5 per cent.
A more or less concentrated acid, scented with spices, was much
used in the middle ages under the name of " aromatic vinegar," to
drive away plague. Glacial acetic acid dissolves considerable quan-
tities of camphor and essential oils, and does not wholly deposit them
on dilution.
Acetic acid is the chief product of the action of Mycoderma aceti on
alcohol. When it has reached a certain amount, it checks and finally
stops this fermentation, and, if sufficiently strong, it inhibits the
growth of all bacteria, hence its use for pickles, <fcc. But, as is well
known, if the vinegar be weak, it turns cloudy, and itself undergoes
a putrefactive change. The old idea that vinegar is an antiseptic is,
therefore, only a question of degree, inasmuch as most micro-organisms
thrive best in a neutral or alkaline medium ; any acid whatever will
act as a restrainer of their growth (see Hydrochloric and Sulphuric
acidSf pp. 69 and 97). Calvert and M'Dougall say that 10 per cent,
of acetic acid was necessary " to prevent animalcules in beef-juice and
egg-albumen for six days. The effect of 10 per cent, on animalcules
in already putrid beef-juice was none." Liebig defended the popular
opinion by pointing out that it fixed ammonia and the organic bases
Accompanying fermentation.!
" Aromatic vinegar," diluted with water, is frequently used to bathe
ihe bodies of patients in typhoid fever and scarlatina; it certainly
• Am. Chem. Joum., voL vii., p. 12. t Vallin, Diamfictants, p. 155.
15
BISINPEGTION AND DISINFECTANTS. )
assists desquamation, acts as a cooling tonic to the skin, aftd removes
or hides any offensive odours. It lends itself admirably to mixing
with resorcin or a sulphocarbolate (p. 158); so yielding a powerful
and eflBcient antiseptic. The acetates are not antiseptic.
Pyroligneous Acid, or crude vinegar, is used in curing hams and
fish. It owes its undoubted antiseptic power chiefly to the creosote it
contains.
Propionic acid, C2H5COOH, has been tested by Duggan on
B. subtilis.*
Glycerine, C3Hg(OH)3, is a colourless, inodorous, and neutral syrup,
of specific gravity 1*27, boiling with partial decomposition at 290° C.
It is miscible with water and alcohol, and dissolves a large number of
salts and organic compounds. Under ordinary circumstances it is not
fermentible. Strong solutions are antiseptic, but weaker ones undergo
fermentation, yielding butyl alcohol, caproic and butyric acids, and
other products of very disagreeable odour. It has been used for the
following purposes : —
. 1. On account of the sweet taste, non-fermentibility, and antiseptic
tendency, it is largely used for sweetening wines, temperance drinks
(e.g., " Hygeia "), syrups, artificial cordials, and " British wines," and
for the preservation of beef-juice extracts. On this subject Lehmann
remarks! : "An addition of glycerine, as it can be practically applied,
should not be pronounced hurtful, for, even if large quantities of
glycerine taken at once act as a purgative (say 15 to 30 grammes), and
if very large quantities have an action resembling that of alcohol, there
is no doubt that the addition of a few grammes of glycerine (5 grammes
per litre) is perfectly harmless in such dilution. Experiments on the
guinea-pig, a very susceptible animal, prove ^ gramme daily per kilo-
gramme of body weight can be mixed with food without injury."
Miquel J says that to prevent putrefaction of bouillon it is necessary
to add 225 grammes of glycerine of specific gravity 1-25 to a litre —
a very large dose, which implies that an amount to preserve food
would also confer a penetrating and unpleasant sweetness. It has
also been employed instead of sugar in beverages for diabetic patients,
but causes purgative and griping effects. No prosecution is recorded
under the Food and Drugs Acts.
2, In surgery, to keep the skin pliable. It does not maintain the
surface moist, as, being very hygroscopic, it acts as a drier ; on this
account its habitual use for the hands or face i^ well known to make
the skin transparent, thin, and wrinkled. Bacteria and insects are
killed by undiluted glycerine, since, having very low diff'usive power,
* Am. Chem. Journ., vol. vii., p. 62. t Hygiene, 1893, vol. xi., p. 247.
X Org. vivantSf chap. 9.
COMPOUNDS BELATED TO THE ALCOHOLS. 211!
it causes death by desiccation. Germs, with thicker envelopes, resist
it indefinitely, and on dilution commence growing rapidly. Its
chief use has been as a medium for other medicaments, which it
keeps liquid and allows to readily diffuse. It is largely employed in
suppositories.
3. Glycerine soaps do not enjoy the same repute as formerly, on
account of the above-mentioned objectionable action on the skin if
their use is long continued. " Glycerinum saponatum " is largely used
by Prof. Hebra in his clinic at Vienna by reason of its rapid solubility
in cold and warm water, and its advantageous property of dissolving'
a large number of substances and of holding other pulverulent insoluble
substances in suspension.* It is a faintly yellowish, more or less
elastic mass, perfectly inodorous, and melting at the body temperature.
Its composition varies from 80 to 92 per cent, of glycerine, with 20 to
8 per cent, of a neutral cocoa-nut oil soda soap.
4. Hams and dried fish have been soaked in 20 per cent, glycerine
with the idea of preservation.
Boroglyceride has been described at p. 101.
Oleic Acid, the fats, "Lanolin," &c., have no antiseptic power in
themselves, but act as convenient vehicles for the application of anti-
septics. Oleates of mercury, zinc, <kc., have, within late years, been
found to possess a rapid absorption, to be more powerful than simple
ointments, and to be less irritating. It has been pointed out (p. 151)
that " carbolic oils " are less efficient than aqueous solutions.
Oils and ointments when applied to the skin may prevent infection
by the exclusion of the germs, but Vicario has observed that the
fixed oils may contain germs, and that both they and any solutions
to be mixed with them must be sterilised by heating to 100° C, or
preferably to 120° C, in a digester, especially in the case of hypo-
dermic injections of guaiacol, iodoform, and eucalyptol with olive oil,
for phthisis, kc. f
Petroleum Jelly and the paraffins, although almost insoluble in
water, are used diffused through it or through soap and water, as in-
secticides in horticulture. Under the name of vaseline it is used as
a medium for antiseptic compounds.
Marco Polo, in the thirteenth century, said that petroleum from the
Caspian Sea was used "to anoint camels that had the mange."f
Vegetable Acids, like tartaric, citric, and malic, have the general
power of inhibiting bacteria which prefer a neutral to an acid medium,
but their effect is much less than that of mineral acids, and, as is well
• Pharm. Zeit., July 19, 1890; Pharm. Joum., 3rd series, vol xxi., p. 1,040.
t American Druggist, June 15, 1891.
t Encyclopcedia Brilannica, vol. iii., p. 259,
228 DISINFECTION AND DISINFECTANTS.
known, their solutions quickly become covered with mould in warm
weather. Reinsch * states that '028 per cent, of tartaric acid in water
" began to diminish the bacteria, and 0'2 per cent, killed them."
Patent No. 1,297, 1893, proposes the use of tartaric acid for purifying
water, and a filter has been devised to carry out this idea. Many
patents use tartaric and malic acids to increase the solubility of boric
acid and borax {q.v., p. 102) ; it would seem as if they would rather
diminish the eflficiency by providing nutrient material, as exemplified
by Pasteur's solution, which is used for growing organisms.
Oxalic Acid is an irritant and corrosive poison, and is said to be
antiseptic. Its solutions certainly do not develop organisms; even the
oxalates only allow their growth slowly. But in practice they are
inapplicable. Succinic acid is slightly antiseptic.
CHAPTER XII.
PEACTICAL METHODS.
Towns : Limited Areas — Administration. Sewers and Drains : Ashpits and
Dust-Holes. Houses : Walls and Wall Papers — Furniture and Wood Work
— Sinks. Sick Rooms : Isolation — Clothing — Excreta — Removal — Light and
Air — Spray — After- Disinfection — Phenol — Sulphurous Acid — Chlorine —
Liquid Disinfectants by Spraying — Hot Solutions — Cisterns — Water-Closets
— Earth-Closets — Middens — Cesspools — Infection by Flies — Automatic Dis-
tributor — Wood Paving — Urinals — "Urinal Cakes"— Stables — Pigstyes and
Cowsheds — Cattle Markets and Fairs — Slaughter-Houses — Dairies — Bake-
houses — Pigeon and Fowl Houses — Rabbit Hutches— Cats and Dogs — Vehicles
— Skins, Furs, Wool, and Hair — Rags. Disinfection of Air : Impurities —
Sewer Gas — Vaporisers and Filters for Air — Water and its Purification.
Preservation of Timber : Copper Sulphate — Creosote Oils.
In early times it was almost considered presumptuous to combat by
natural methods the great plagues which frequently devastated the
country, and only trifling efforts were made to control the ordinary
infectious diseases that are always with us, such as diphtheria, typhoid,
and other fevers. It is true that vinegar, camphor, and perfumes were
used to protect the person from contagion, and that fumigation with
aromatic woods was sometimes employed, but these, as has already
been shown, have only feeble powers in this direction. As the popula-
tion increased, and overcrowding in towns became general, the fatality
from epidemics became excessive. Amulets of all kinds were the only
remedies relied on. Even now, in the bubonic plague which was
* Centrcdhl.f. BahterioL, 1891, vol. x., p. 415.
PRACTICAL METHODS. 229
recently raging in Hong Kong, the faith of the people in charms,
and their opposition to sanitary measures, was so intense that it was
only under military force that the work of sanitation could be under-
taken. Yet it is scarcely open to doubt that this plague, identical in
its symptoms with the great plague of 1666 and other years, as shown
recently by Kitasato, and is still endemic in certain parts of the East,
the Black Death, and the Sweating sickness, and, to a great extent,
the cholera, are only kept out of Europe by modern applications
of sanitary science. Harvey in the sixteenth century, and Bishop
Berkeley in the eighteenth, seem to have been the first to advocate
the combating of disease from the outside. England was the first
nation to organise a systematic campaign against infectious diseases.
After the great outbreak of cholera in 1832, Parliament energetically
resolved to frame regulations for public health. These emanated
from the elected authority, and not, as in other countries, entirely
from the police. The Public Health Act of 1848 constituted the
Local Government Board as the executive sanitary power. Statistics
were collected. The country was divided into limited areas, which
were distinguished as Urban and Rural Sanitary Districts, each with
its Local Board of. Health. The Urban districts included all towns
except London, which has a special sanitary organisation. Scotland
and Ireland also have in part their own laws. The Urban authority
centred in the Town Council. In rural districts the Board of Health
and the Guardians are now merged in the Rural District Councils.
Each body sends an annual report to the Local Government Board,
which from time to time sends out recommendations in the form of
a circular to the Local Authorities. Measures of disinfection are per-
formed, superintended, or directed by the Sanitary Officer (Inspector
of Nuisances) under the control of the Medical Officer of Health.
Sewers and Drains. — It has already been pointed out that the old
system of pouring large quantities of liquids, like carbolic acid, sul-
phate of iron, or permanganate down the drains with the object of
disinfecting the sewage, is really useless, inasmuch as the reagents
are practically lost in the immense volume of water, and fail to
reach a proportion sufficient to destroy the bacteria, although they
may partially remove the smell. If an attempt is made to hermeti-
cally close the sewers, as was formerly supposed to be the best method
for preventing a nuisance, the sewer gas, by backward pressure of
rains or tides, passes through any form of trap into the houses, and,
although sewer gas has been proved, probably owing to subsidence in
the quiet atmosphere, to be almost free from germs,* yet there can be
* Joum. Soc. of Chem. Ind., 1888, p. 911 ; also J. Parry Lawes' Report to the
L. C. C, 1893.
530 DISINFECTION AND DISINFECTANTS.
no doubt that it has a depressant effect, and lowers the vitality in such
a way that men subjected to its influence are therein predisposed to
infection. The fact that a few germs may be present must also be
borne in mind. Consequently, the modern system is mainly confined
to ventilation and flushing. Charcoal and disinfecting ventilators
are elsewhere discussed (p. 246). Drs. Arthur and Illingworth have
recently proposed a new system of sewerage in which the side drains
enter at the bottom of the main sewage.*
In workmen's dwellings it is customary in London for the gratings
of the house drains to be daily sprinkled with some disinfecting
powder. M'Dougall's, Calvert's, or a pine-oil powder such as Sanitas,
are commonly used. In a number of experiments on this practice,
gratings were selected which evolved a distinct quantity of sul-
phuretted hydrogen, as proved by lead paper 1 foot over the drain
being in most cases discoloured. After sprinkling with either of the
powders, the fetid odour, both of sulphuretted hydrogen and of sewage,
seemed to be actually removed, and not merely disguised, as the lead
paper was no longer affected. The effect, however, only lasted from
an hour to an hour and a-half ; after this the smell was as strong as
ever, and the lead paper was again discoloured. The odour was
most powerful in the mornings, or on the approach of a thunder-
storm. It may be mentioned that in this instance several cases of
diphtheria had occurred, and a general cachexia was noticed in
the inhabitants, in all probability attributable to this sewer gas.
Yet in many of these places, when a complaint is made, a roadman
is sent with disinfecting powder, and the nuisance is temporarily
abated, instead of the defect in the drain being seen to by the sani-
tary inspector. So that this method of disinfection is not only
useless, but is positively to be condemned, as it leads to a false idea
of safety, and hinders genuine sanitation. Sanitary inspectors should
always visit these places in the early mornings before the roadmen
have sprinkled the disinfecting powder.
Chloride of lime retains its power for a very much longer time, on
a,ccount of the gradual evolution of chlorine by the action of the
carbonic acid of the atmosphere. But even this is inefficient. Its
smell to most people is exceedingly unpleasant, and the gratings and
pipes are quickly corroded ; hence its general abandonment for this
purpose. A daily flushing of the drains, except in rainy weather, with
water seems to be one of the best methods for preventing a nuisance.
It has been proposed in several recent patents to suck the smoke from
house and other fires into the sewers, not only to get rid of the soot,
but with an idea of disinfection, but as it is necessary for workmen to
* Sanitary Feord, 1894.
PRACTICAL METHODS. 231
enter the sewers, it is not easy to see how the smoke could be tern-;
porarily suspended.
As to Ashpits and Dust-holes, if they are frequently emptied, and
care is taken to burn putrescent matter and not to throw it into these
receptacles, there is not much danger. Portable ash-bins of galvanised
iron are much used in London. To sprinkle disinfectants over the
refuse is futile, though they may be used with some advantage in the
empty dust-bin after removal, and over the contents of the dust-carts
in their passage through the streets. Stingl and Neuman have a
patent* for an improved refuse collecting van, with double dust closure
and an automatic disinfecting device. A portable petroleum destructor
for house refuse has also recently been advocated for this purpose.
Most urban authorities have now a difficulty of disposing of their
refuse, and many refuse-destructors and cremators are now on their
trial.
Houses. — Fresh air, light, and frequent cleansing seem to be the
essentials to be aimed at in thickly-populated districts. In washing
floors a strong carbolic soap, or better, a cresylic preparation, are very
useful. Curtains and bedding must be occasionally brushed and
shaken in the open air. When sweeping floors and carpets, teaJeaves
or damp sawdust should be used to prevent the difi"usion of germs in
the dust. Oil paint, or a well-varnished paper, are preferable for
walls, as they can easily be washed. Flock papers have become
obsolete, from their forming such a favourable nidus for the growth of
organisms. Ordinary wall-papers can be cleansed down with the
crumb of bread, which mechanically removes any bacteria.
Hygienic Wall-papers prepared with various disinfectants incor-
porated in the pulp have been suggested. Mercuric chloride has even
been proposed to be introduced, but its use should not be permitted
on account of the danger of its being evolved in the dust. Resorcinol,
1 in 2,000, is patented by Sinclair and Brown for this purpose. f
Salicylic acid is non-volatile and inodorous, but it is doubtful if it
would be efficacious. It has been proposed to incorporate it with the
plaster coating of walls (p. 198). It always communicates a pinkish
colour, owing to the presence of iron salts. Herr Kosinski of
Warsaw has invented a machine for drying and disinfecting walls.
It is a portable air-heating chamber with pipes to the outside of the
room, capable of heating surfaces of about 108 square feet by an air-
blast directed by radiating pipes on to the wall or other surface. The
air is mechanically renewed at the rate of about 1,000 feet a minute.
It is also intended for large disinfecting chambers, in which the
rapidity with which the air passes, combines with the high tempera-
• No. 47, Jan., 1894. + Patent No. 12,217, 1886.-
232 DISINFECTIOK AKD DISINFECTANTS.
ture (stated in the report to be 660° F., but this is obviously an error)
in bringing about the desired result. It is also suitable for warming
buildings, and for removing vapour and moisture from crowded rooms
— e.g., in a theatre, after the exit of the audience, to prevent the con-
densation and settlement of injurious moisture and dust. An official
commission at Warsaw proved that a private house, the building of
which was commenced in May, 1882, with the capacity in ground floor
and first storey of 7,000 cubic feet, was completely dried in fourteen
days, and severe sanitary inspection proved the building to be com-
pletely sterilised.
Furniture and Woodwork can be washed and scrubbed, or, in special
cases, should be washed with 1 in 1,000 mercuric chloride (in a few
instances this may cause discoloration). Beeswax and turpentine
are better than the common furniture polishes for polishing, as the
surface is to some extent disinfected and rendered non-absorbent.
All cracks and crevices should be carefully filled up with putty
to prevent the lodgment of vermin or germs.
Sinks, if made of stoneware, can easily be cleaned. Here Oondy's
fluid (permanganate) is serviceable, but strong soda is ordinarily
better. For toilet utensils sodium hypochlorite (chlorinated soda)
in 5 per cent, solution should be occasionally used, also for milk
cans and pails. In the case of metal baths it should not be used
too strong as it removes paint. Bedsteads, in addition to scrubbing
with soap and water, can be afterwards washed with chloride of
lime and water, 10 per cent., and left in the air till the odour
has almost disappeared. Paraffin oil is sometimes used, but its
odour is very persistent. Polished floors are to be recommended
in preference to porous floors and carpets.
Sick rooms cannot be disinfected in presence of human beings.
All placing of saucers with chloride of lime, permanganate, &c.,
under the bed, or about the room, all hanging up of sheets dipped in
disinfectants, are simply illusory. Similarly fumigation by medicated
lamps or candles, burning pastilles, or brown paper, are useless.
Sufficient of the disinfectant to kill the micro-organisms of the air
would make the air unfit to breathe. The following precautions, how-
ever, will be of service.
1. Isolation. — If possible, the other inmates of the house should
live on a different floor. Where this, on account of poverty or other
cause, is unattainable, contact should be carefully avoided.
2. Clothing. — The attendants should wear cotton and linen, not
woollen, garments. This is now compulsory in hospitals and most
institutions. The greatest personal cleanliness should of course be
observed. The following is the best way of removing soiled clothing
PRACTICAL METHODS. 233
from the room : — At the bottom of a large air-tight tin trunk, such as
is used for travelling to India, is placed a piece of felt or blanket, or
three or four thicknesses of flannel. This is sprinkled with crystals of
carbolic acid, and covered with a linen cloth. The crystals will soon
deliquesce, and soak into the stuff. The lid should never be left open.
The soiled clothing is put in, and when full it is left for an hour for
the phenol vapour to penetrate, and then carried out into a yard,
where it is filled with boiling water containing soda, and washed as
soon as possible. The washing must never be done, nor the clothes
hung out to dry, on the same day as the ordinary house washing, nor
should they be ironed or starched in the same room or with the same
utensils. This dry method of removal of clothing is probably better
than the usual one of plunging into a disinfectant solution (phenol or
mercuric chloride), as it is easier, and the weight of the water and
constant carriage are avoided.
3. Excreta, vomit and sputa should be received into about a pint of
mercuric chloride solution, 1 per mille, with 10 per millo of common
salt and 1 per mille of hydrochloric acid, and coloured with indigo to
avoid mistakes. A large quantity of such a solution should be kept
ready. (See also p. 141.) Dr. Fischer recommends aniline water as
the best disinfectant for tuberculous sputa (p. 184), "Five per cent,
phenol did the same in twenty-five hours ; mercuric chloride, 1 in 500,
failed. Dry heat of 100° C. sometimes failed, though it acted for sixty
minutes. Boiling ten minutes, or steam for fifteen minutes, succeeded."*
Disinfected excreta must not be thrown away before the agent has
had time to penetrate. If disease begins in houses where the sick
person cannot be properly accommodated and tended, medical advice
should be taken as to the propriety of removing the patient to an
isolation hospital. Where dangerous conditions of residence cannot
be properly remedied, the inmates, while unattacked by disease, should
remove to some safer lodging.!
4. Light and air should be freely admitted. Vallin strongly recom-
mends the use of water spray in the room, as he says that the water
entangles the bacteria and dust, and the dissolved oxygen in the water
destroys them. He also approves the use in the water of a small
quantity of resol (dimethyl-resorcin), a body proposed by M. Pabst, as
agreeable and non-corrosive. A 1 per cent, solution of peroxide of
hydrogen, or a preparation like Sanitas might also be employed for
the same purpose. The sick person should be protected by a screen
from this process, from draughts, and from too much light. % It is
well known what benefit is derived in some lung diseases from the
* MUthe'U. Kais. Oesundh., 1884. t Circvlar of Med. Off. Local Gov. Board.
X Dia'mfectants, p. 407.
334 DISINFECTION AND DISINFECTANTS.
common bronchitis kettle. Dr. W. Ferguson has suggested its use
as a fumigator in pneumonia and diphtheria by the following simple
modification: — "Take an ordinary bronchitis kettle, remove the first
joint, and replace it by a common tin funnel loosely filled with tow.
Pour on the tow 1 drachm of pure phenol, and at intervals more. The
steam carries off the phenol."* Curtains, hangings, carpets, and all
^unnecessary furniture should be removed.
After-disinfection. — Phenol, chlorine, and sulphurous acid have each
had their advocates.
{a) Plienol. — Pouring strong carbolic acid on a hot shovel is
dangerous to the operator. Calvert manufactures a perforated iron
cylinder delivering a mixture of 2 parts phenol and 1 part water on
to a red-hot iron heater ; the whole is compact and can be carried by
a hook. There is also Savory and Moore's vaporiser, in which phenol
falls on a hot plate ; and many others. But phenol is not reliable as a
disinfectant {Miquel and others), and the smell remains persistent.
(6) Sulphurous Acid. — After the removal of such articles as are best
disinfected by heat, and the closure of windows and crevices, the gas
in ample quantity should be evolved, the doors being closed for six
hours or more. The amount of gas required for the disinfection of a
moderately-sized room can be obtained by burning 1| lbs. of roll
brimstone in a pipkin over a small fire placed in the middle of a room,
with an old tray or the like to protect the flooring. These processes
should be effected by skilled persons acting under the directions of the
Medical OflScer of Health. All wall-paper should be stripped from
the walls and burned, and the same room ought to have its ceilings
and walls thoroughly washed and lime-whited.f Boake's liquid sul-
phurous acid, bottles or tins, are much more convenient in careful
hands (see p. 92).
(c) Chlorine. — 3 lbs. of good chloride of lime and 3 lbs. commercial
hydrochloric acid should be used for every 1,000 cubic feet. This
quantity should be divided into several parts and placed in deep
vessels as high as possible (since chlorine gas is heavier than air), and
the acid allowed to drop in gradually by a funnel partially blocked by
a cork pierced with a small hole (try the dropping rate beforehand
with water). The room should then be closed for twenty-four hours.
Before opening, cover the mouth and nostrils tightly with a towel
soaked in weak solution of ammonia, i to 1 per cent. Close the other
doors of the house and open the windows. Sprinkle a little strong
emmonia in the passage around the room door. Now open the sick-
room door, rapidly throw the windows wide open, and as quickly
r.etire. Another person similarly protected should be at hand in case
* Lancet, 1880, vol. xi., p. 757. ' f Circular of Med. Off. of Health, L. G. B.
PRACTICAL METHODS.
235
of accident. If the eyes are affected, wash them with luke-warm
water, without any ammonia. In case any irritation remains in the
lungs or nose, inhalation of the vapour of ether will afford relief.
With these precautions the operation is perfectly safe. All metal
fixtures should be removed beforehand; if this is not possible, they
must be well rubbed
over with vaseline or
lard. This is un-
doubtedly the most
thorough method of
disinfection,
processes,
there is a
Fig. 20. — The Equifex disinfectant sprayer.
In both
however,
common
omission. Inasmuch
as neither dry chlorine
nor sulphurous acid
will act, it is necessary
to generate steam by
a boiler or large kettle
over a good fire for
some hours before com^
mencing, so as to make
the whole room and the
air thoroughly damp.
Then put out the fire,
close the chimney, and
proceed to the disin-
fection.
(d) Non-volatile dis-
infectants can be ap-
plied by mechanical
means. Thus bleach-
ing powder can be used
as a wash, and the
walls, floor, and ceiling coated by means of a brush. Mercuric chloride
solution and formalin, or, in fact, any liquid disinfectant can be sprayed
into the room. The Equifex sprayers have been specially devised for
this work. Two forms are shown in Figs. 20 and 21. The spray is so
constructed that the fineness of division and the force and velo-
city of projection can be varied at will. For this purpose the
channel for the disinfectant is arranged to reduce the velocity of the
liquid at the point of delivery to a rate which is very small, and
capable of being exactly controlled by turning a cock. For a given
^^\^^\^\\\^^^^\\^mMmmmw
Fig. 21. — The Equifex disinfectant sprayer
(another form).
236 DISINFECTION AND DISINFECTANTS.
velocity of air, regulated by another cock, the force of projection will
therefore be determined by the velocity of the air, which is controlled
by the pressure to which the pump is worked, and the degree to which
the air cock is open. The importance of a fine division of liquid
depends on the fact that it enables the work to be done with the
minimum useful amount of disinfectant, saving the expense and incon-
venience of waste liquid.
The parts containing the disinfectant are lined with ebonite, so that
these sprayers may be used with any liquid disinfectant without any
risk. The cost will vary slightly with the disinfectant used. Taking
perchloride of mercury 1 in 1,000 solution, it is found that an ounce
of salt disinfects more than 3,000 square feet of surface. The time
occupied in the operation is about an hour per 1,300 square feet.
Clothes, bedding, mattresses must be removed at once in a closed van
to a disinfecting station, to be treated with superheated steam. Dry
hot air is now only used in special cases (books, leather, and some
other materials), and in practice the apparatus is no longer constructed
(see p. 27). Occasionally, however, a baker's oven may serve, if not
for the destruction of the spores of splenic fever, for killing the non-
sporiferous bacteria of cholera, typhus, and diphtheria, and especially
of animal vermin {Klein). The bodies of persons who have died of
infectious diseases should be at once wrapped in a cloth soaked in
1 per cent, solution of mercuric chloride prior to burial or cremation.
Adolf and Heider find that hot solutions of disinfectants are much
more active than cold.* In Belgium infected clothes are boiled in a
solution of zinc chloride, or with a mixture of 240 grammes zinc
sulphate and 120 grammes salt dissolved in a pail of water. Com-
mercial zinc salts cannot be used, as the presence of iron salts causes
them to produce stains on linen.
In Hospitals special precautions are obviously necessary, and it is
natural to expect in them the most improved methods of disinfection.
Most of the larger hospitals in England are now fully equipped with
modern steam disinfecting plant for bed-linen, clothes, and the like,
and, in one or two, special cremating apparatus are in operation for
the destruction of infectious stools, bandages, dressings, and valueless
articles. The floors of the wards are preferably of polished wood, and
they and the walls near the beds may be mopped with 1 in 20 carbolic
acid solution from time to time. The bedstead and bedding may be
conveniently disinfected by sulphurous acid, and the smaller wards
may also be disinfected by this gas. Carbolic acid, 1 in 20, can be
used in bed pans, spittoons, and other dejecta receptacles. For
surgical dressings, diluted liquor soda chlorinate or carbolic acid
* Arch, f. Hygiene, vol. xv., p. 55.
PRACTICAL METHODS. 237
(1 in 40) are generally employed. Eucalyptol is still frequently used
in bronchitis kettles for diphtheria and pulmonary diseases. In the
operating theatres and obstetric wards mercuric chloride 1 in 1,000
finds most favour. In London the Metropolitan Asylums Board has
been constituted a Local Authority under the Diseases Prevention
Act, 1883 and 1885, and in 1891 its powers were increased so that it
is enabled to secure accommodation for cholera patients in the event
of an outbreak. The arrangements in 1892 provided for 1,700 beds,
not including 250 available at the Board's Hospitals. These cholera
beds were secured partly by the acquisition of sites for temporary
huts, and partly by special arrangements made with the larger hospitals,
infirmaries, and workhouses. This constitutes the first line of defence
in London in the event of an outbreak.
Cisterns for drinking water must not, obviously, be connected with
the water-closet tanks. They must be occasionally scrubbed out, every
three or six months, according to the quality of the water. If made
of lead, care should be taken not to expose the metallic surface, or
lead may get into the water. If any foul deposit, or confervse, have
collected on the sides, the cistern should be brushed over repeatedly
with a solution conta,ining 5 per cent, permanganate crystals and 5
per cent, sulphuric acid. Householders can have a quart of this
solution made up at a chemist's (water 1 quart, potassium perman-
ganate crystals 2 ounces, sulphuric acid 2 fluid ounces ; cost about
6d.). The solution should be used till the pink colour of the perman-
ganate remains for an hour, then it should be well flushed till all colour
has been removed. A slight brown coating of peroxide of manganese
on the walls will be advantageous, by serving as an oxidiser, and
preventing further growth. Several inventions have been introduced
for allowing a small quantity of permanganate solution to be constantly
admixed with the water, but any admixture of a chemical, except a
minute quantity of slaked lime, properly used as in Clark's process
(p. 15) would be injurious; they are, however, of service in small
cisterns used for closets and urinals. One of these inventions places
the crystals in a horizontal bottle with a narrow tube, another in
tablets,* a third is a closed porous pot hung in the cistern.f Straling's
sanitary tube is somewhat similar. When a rain supply is used for
drinking in cottages in remote parts, care must be taken that the
water-butts are kept very clean. Iron tanks are better than wooden
barrels.
Water-Closets should be of modern patterns, admitting of washing,
flushing, and proper cleaning of walls and pans. The walls should be
of cemented tiles or lime-washed. The solution of acid permanganate
♦ Symonds, Patent No. 8,351, 1885. t Austin, Patent No. 4,981, 1885.
238 DISINFECTION AND DISINFECTANTS.'
should be used occasionally to cleanse the pans. Chloride of lime'
should not be used, as it corrodes the metal fittings, and has often
caused serious mischief by eating holes in lead or iron siphon traps.
Mercuric chloride also corrodes lead pipes. The flush of water at each
using should be preferably 3 gallons. A valve closet, though rather
expensive, seems to be the best form for indoor use.
Earth-Closets are daily diminishing in number, owing to the fact
that the rapid and inoffensive removal of excreta is most economi-
cally efiected by the water-carriage system. The mass of water with
which each excretal mass is mixed, the perpetual movement of water
in the sewers, and the low temperature in them, are unfavourable
to bacterial development. Pathogenic microbes soon die in a mass
of water owing to their conflict with non-pathogenic microbes and
perhaps also as the result of other unrecognised factors. The system
is, however, objectionable, because of its fouling so large a mass of
water. It is nevertheless a mistake to suppose that faeces pollute
sewage any more than any other waste matter discharged into the
sewers.
It was with the object of saving the manure, as well as the
immediate disinfection of the faeces, that Moule, in 1863, intro-
duced the earth-system of closets. Earth is popularly believed to
be a universal disinfectant, yet it abounds in microbes, some of
which are pathogenic (Koch). Indeed the very nitrification, upon
which the purifying action of earth is so largely dependent, is in
great part due to the life and growth of microbes. The earth should
be dried or, preferably, baked before using. In some districts this is
done every day over the oven ; it could also be baked in larger
quantities over a baker's oven or in a special furnace. So dried the
earth is very absorbent, and instantly removes all odour when only
a light covering is spread over the excrement. But its effective
use is ruined by the discharge of urine at the same time ; if this
could be kept separate and used for agriculture, the process would
be excellent. Unfortunately the manure is of hardly any value,
on account of the rapid loss of ammonia. Dr. Rolleston showed that
as the earth became damp, this gas was evolved. Success depends
more on the quality than on the quantity of earth. Sand and gravel
are inert, chalk feeble and dry clay good, whilst garden soil, loam, and
peat give the best results;* 2 lbs. of dried earth at least are required
for each evacuation. At Wimbledon camp in 1869, when 140 tons
of dry earth were used in a fortnight for 30 tons of excreta the
deodorisation was complete.! Green and white moulds destroy the
faecal matter, and in 5 or 6 weeks it is undistinguishable from
* Bnchanan and Radcliffe, Heport of 1869. t Lance(, July 24, 1869.
PRACTICAL METHODS. 23^
ordinary earth, so that it can be safely spread on gardens or on
land, provided that it is ploughed or dug in. Although of so little
manurial value, containing only about O'l per cent, of nitrogen and
0*5 per cent, of phosphoric acid, it has been found beneficial for
soils. Although pathogenic organisms are not killed by the process,
they do not in jiractice escape, and there is no record of epidemics
having been caused. For places without a copious water supply, this
system is better than pails, and much superior to privies. Dr. Poore
has recently advocated an earth system for rural sanitation.
The Goux-Thulasne Method is a combination of the earth and the
pail systems. In an iron barrel with handles a slightly conical core is
held, and the intervening space packed with dry earth or a pulver-
ulent disinfectant. When the core is withdrawn, a cavity of the same
shape is left. These are carried round on a dray and left at the houses.
At the end of a few days they are collected, shaken so as to cover the
exTcreta with powder, and covered with an air-tight iron lid before
removal. They must be kept from the rain. There should be urinals
in the neighbourhood, or a funnel can be arranged in the front part of
the closet opening to collect the urine separately, so that the earth or
powder is not wetted. This is an excellent mode of disinfection of
fjecal matters, especially in sick rooms when the excreta must remain
all night in the room.
A Self-acting Earth-Closet has an upright box at the back containing
the dry earth, &c. By a rack-work and lever worked by a handle in
the ordinary water-closet fashion, a valve at the bottom of the box is
opened, allowing a certain quantity of earth to fall on the fseces at
each evacuation. The receptacle is a large ordinary zinc pail. Or the
arrangement may be made automatic by a hinged seat. By Norris's
patent,* the solids are separated by a grating and mixed with earth,
the liquid portions pass down the drain, which is ventilated by a
current of fresh air and connected with an ordinary ventilating shaft.
Pail System. — In villages and some towns on the Continent the
excreta are discharged into pails, which are collected at night-time,
and the contents, with or without a perfunctory disinfection, emptied
into ditches or pits, which when full are covered up with earth.
From this primitive and dangerous practice, the material has come to
be called night-soil. Even this is, however, preferable to the old
system still surviving in English country districts, and even improperly
permitted in some towns (but not in London) — namely, that of
Privies, wherein the fseces and urine fall into a brick well, which is
cleared out at intervals. The soil is infiltrated, and the infected
drainage has often peneti-ated for years into wells used for drinking
* No. 20J26, 1S91.
240 DISINFECTION AND DISINFECTANTS.
water, and has been the cause of numerous epidemics. At Rochdale
an improved pail system is giving good results. The excreta and
ashes are collected separately and the former converted into dry
manure, whilst the latter yields fuel for a refuse destructor and steam
production.*
Cesspools can only be dealt with by pumping out the contents and
distributing them over land. They cannot, obviously, be disinfected.
S. von Gerloczy,t in an investigation of disinfectants at the Pesth
Hygienic Institute, found that a practical disinfection of night-soil
was all but impossible. Even 2^ per cent, of mercuric chloride was
insufficient to render it germ-free (costing £9, 10s. per cubic yard).
Complete disinfection resulted when 4 per cent, of cupric sulphate was
used, but the cost of it would also be prohibitive. In sewage matter
1 per mille of copper sulphate destroyed all germs and rendered it
clear and inodorous.
According to the model bye-laws of the Local Government Board,
the occupier of any premises shall cleanse every earth-closet on his
premises, or fixed receptacle, at least once every three months (this
interval is found sufficient for sanitary purposes, as under the proper
use of dry earth the stools and even the paper become disintegrated
and disappear without foetor in the compost — Newsholme) ; those with
a movable receptacle at least once a week (so that the pails may be
manageable during scavenging) ; privies and ashpits once a week ; and
cesspools every three months ; and that between 6 and 8.30 a.m. in
summer, and 7 and 9.30 a.m, in winter.
One of the great dangers of leaving faecal matter exposed is the
visits of flies. The bacteria of tubercle, splenic fever, typhus, and
European cholera pass through the digestive organs of flies, and re-
appear in their excrements with unabated virulence. J They are also
carried adhering to the feet and legs of these and other insects. A
covering of chloride of lime or of a coal-tar powder has the merit of
keeping them away. There is a vast number of patents having for
their object the introduction of disinfectants into the pan or into the
flush water of closets. Cakes of naphthalene, tablets of plaster of
Paris mixed with manganate or permanganate, zinc sulphate, thymol,
&c., are of little value. Automatic distributors designed to keep the
drains flushed with liquid disinfectants give better results. The
construction of Jeyes' model is easily understood from the appended
illustration.
The contrivance is filled by removing the screw seen in the front,
* Joum. Soc. Chem. Ind., 1895, p. 340.
t Deutsche Vierteljahreab. 6ff. Oesund., 1889, p. 433.
t Centralblatt/. BacierioL, 1888, vol. iv., p. 486.
PRACTICAL METHODS.
241
then filling the receiver. After the screw has been tightly replaced,
the machine is raised to a vertical position and suspended inside the
water waste-preventor in the water-closet. On the water rising, the
ball acts on the lever, moving the
plug, which pressing into the well,
as is seen in the figure, expels the
fluid in the trough, which falls
over the sides and mixes with the
waste water. Each discharge of
water from the cistern, followed by
its refilling, automatically mixes a
portion of the fluid with the water
for use. Panario* and Skudderf
have also invented similar con-
trivances. In the latter the flush
passes through a perforated tube
containing the disinfectant in the
upper portion. Similar devices for
automatically discharging perman-
ganate have been proposed (see
under Cisterns, p. 237). To con-
tinually supply sufficient of a dis-
infectant to a closet would, however,
be very expensive.
Sanitary officers must proceed
with caution in disinfecting private
dwellings, and must give proper
notice, as it has been proved that
an action for damages can be maintained unless the disinfection is
legally carried out. J
Streets are watered and cleansed by the Vestries and Local Boards.
It is important to remove refuse and animal excreta immediately, as the
surface, even when paved, is porous, and the soil is a very favourable
nidus for the growth of micro-organisms, which escape in the dust
(p. 223). Mixing disinfectants with the water in the carts is of
doubtful utility, as the chemical must be much diluted, and the area
to be covered is often large. It is of course impossible to disinfect
the open air. Such a procedure may perhaps ofier a certain restraining
influence on the microbes, but, as ordinarily done, it is often a waste
of public money. The main work must be done in houses, and in
narrow streets and courts. It would be better if these latter were
* Patent No. 4,287, 1891. t Patent No. 10,301, 1885.
t For particulars of such a case at Filey see Lancet, April 10, 1880.
16
Fig. 22. — Jeyes' Automatic Dis-
infectant Distributor.
242 DISINFECTION AND DISINFECTANTS.
paved with asphalt or some similar non-porous material. An asphalt
pavement made properly is aseptic, and to a certain extent antiseptic.
For disinfecting courts and streets a distributor like Bishop's or the
Equifax sprayers (p. 235) would be of service. The former consists
of an ordinary rose-jet capable of attachment to an india-rubber hose
or to the cock of the water supply. A vessel at the side holds a
supply of disinfectant, which is drawn through a tube into the current
of water and ejected in spray through the rose. By measuring the
relative volumes of water and disinfectant passing through in a given
time and regulating the stopcocks, a perfect mixture in any required
proportions can be delivered. It is usually made to work with 1 in
40, 1 in 80, or 1 in 160, by marks on the top, which can be set by
a key. Such an arrangement is also well adapted for urinals, ships,,
stables, &c.
Corrosive disinfectants, such as acids or chloride of lime, could not
be used with this apparatus. The most suitable would be one of th&
cresol or pine-oil class (see p. 160 et seq).
Wood Paving, although it is cleaner than macadam, and less danger-
ous to horses than asphalt, has been seriously objected to for sanitary
reasons by Mr. Isaacs.* The same view is taken by Mr. Morgan in
a recent report to the Liverpool Engineering Society. As the blocks
are almost non-porous, and do not readily decay, the objection to their
use is not general ; no increase of illness itt wood-paved as compared
with other districts has been noticed.! A creosoted wood paving is
now largely used. J. Tottrell % proposes to mix disinfectants, such as
carbolic acid, carbolates, sulphites, or bleaching powder, with the
ordinary cements employed in paving roads, basements, walls, &c.
The cost would be immense, and the utility seems doubtful.
Urinals require somewhat different treatment, on account of the
deposit (containing Bacterium urece and other organisms) which forms
from the urine and promotes ammoniacal fermentation. Their sides
should be made of slate, or of enamelled, not painted, iron; then they
can at intervals be washed down with a solution of sulphuric acid
2i per cent., and permanganate 2 per cent.; this, of course, must not
be put into metal pails unless they are tarred. The sides have been
sometimes constructed of glass, but they are too liable to fracture, and
then the urine penetrates, and putrefies at the back. Well-tarred iron
is the next best material, but is easily scratched, and then rusts into
holes.
One form of urinal-cakes consists of sulphates of copper, iron, zinc,
and soda, with some alum, heated with resin, and pressed. They
* Q. J. San. Institute, June, 1894. t Lancet, July, 1894.
J Patent No. 8,317, 1884.
PnACTlCAL METHODS. 243
absorb ammonia, and are, of course, locally disinfectant, but would not
supersede cleanliness and the process just mentioned. Naphthalene
tablets are almost useless (p. 148). Disinfecting powders are only
temporary in their action.
Stables, pig-styes, and cowsheds require to be regularly cleaned,
and to be periodically disinfected, like rooms, with removal of the
animals, to prevent disease occurring. Some varieties of antiseptic
litter have already been mentioned (p. 12). It is of little use to be
perpetually deodorising with powders. Dryness, ventilation, and
cleanliness are better safegiiards.
For Cattle Markets and Fairs a cresol disinfectant is probably the
best. A description of the chief ones is given at p. 165.
Slaughter-houses are pai-ticularly difficult to disinfect on account of
the large amount of albuminoid matters present. It has already been
noted that it is almost impossible to sterilise blood. Mercuric chloride
cannot be used because of its action on albumen (p. 137). Phenol is
inapplicable for the same reason. Copper sulphate is one of the most
useful agents in these places. Chlorine and sulphurous acids are
rarely to be recommended. Cleanliness and rapid removal of offal are
the first consideratioi\s. Cunliffe and Barlow * subject the refuse to
heat and destructive distillation. Wood charcoal only serves to
deodorise, and does not destroy. Slaughter-houses for infected or
suspected animals are usually situated near seaports, and require
special methods of isolation, and extra precautionary measures to be
adopted.
Bakehouses. — There has been much agitation lately with reference
to their insanitary condition. Under the Factory and Workshops
Act, 1891, local authorities have power to act, but the recommenda-
tions of the London County Council on the bill of 1894 have not yet
become law.
Dairies and the Milk Trade will be alluded to under Food, p. 272.
Pigeon and Fowl Houses, Rabbit Hutches, &c., often become very
offensive, and are dangerous breeding houses of disease. Legislation
with regard to them is difficult and hazardous, but at least more
attention should be given to secure that, especially in crowded
neiglibourhoods, they are kept in a sanitary condition. They should
occasionally be disinfected with sulphurous acid, the animals being
removed. This is only a partial precaution, as their feathers and hair
are likely sources of infection. Some effect is produced by dusting
them with flowers of sulphui*. Poisonous disinfectants obviously cannot
be used.
Cats, from their prowling habits, have been proved to frequently
* Patent No. 19,967, 1890.
244 DISINFECTION AND DISINFECTANTS.
carry infection, especially of diphtheria. Dogs are more easily kept
clean. Rats, as coming from the^ewers, and even mice, are sources of
infectious danger.
Vehicles. — The following is from the Report of the Society of Medical
Officers of Health^ Nov. 19, 1886, on a communication addressed by
the Commissioner of Police to the Metropolitan Sanitary Authorities.
In cases of supposed infection. Sanitary Inspectors are authorised to
disinfect without charge, and give a certificate. " I hereby certify
that cab . . . has been this day disinfected by me after the manner
prescribed by the Medical Officer of Health. Signed . . ."
The cushions, and as much of the internal fittings as are movable,
should be taken out and put in a disinfecting oven, where such is
available. If not, they are well beaten and dusted, returned, and
placed on end so as to expose both surfaces to disinfection. All
exposed woodwork is washed with carbolic soap, and carbolated oil is
smeared over metal work with the view of disinfecting it and also
protecting it from chlorine. The chlorine is evolved inside (see p. 57),
and the vehicle shut and left so for an hour.
A process was patented for enclosing vehicles in a kind of chamber
made of tarpaulin, and then injecting steam or disinfecting spray, but
it does not seem to have come into use, being cumbrous and expensive.*
Skins, furs, wool, and hair are constant sources of infection. Wool-
sorter's disease, anthrax, charbon, and splenic fever, was many years
ago proved by Pasteur to be due to Bacillus anthracis. Machines are
now devised for carrying the dust away by fans, and for disinfecting
by steam ; the trouble is, that the wool will not bear a temperature
sufficient to kill the anthrax spores, which are, moreover, very highly
resistant to chemical agents (see Mercuric cJdoride, p. 136). So that
the only means practicable are cleanliness on the part of the workmen
and the use of fans. Arsenic is used in the preparation of furs and
skins, but of the chemical disinfectants, formalin seems to be the
most suitable for general disinfection of such articles.
Rags are exceedingly dangerous, because they often come from fever-
stricken districts, and convey bacteria as well as vermin. Their
importation in cholera times is generally prohibited, but as they carry
other diseases besides cholera, they are at all times to be regarded
with suspicion. It is difficult for steam or heat to penetrate the tight
bales into which they are compressed by hydraulic pressure.
Parker and Blackman f force hollow screws into the bales by means
of suitable machinery, and then introduce a disinfectant through the
screws, and afterwards air, which displaces any noxious smell. This
apparatus is used in America. An improved process has been devised
• Patent No. 5,434, 1883. t Patent No. 16,539, 1884.
PRACTICAL METHODS. 245
by Paton and Ransom.* Conical perforated pipes are first driven into
the bales, and then hot air is forced into the bales to heat the interior
and prevent the steam which is subsequently introduced from con-
densing. Steam at 10 to 25 lbs. to the square inch is then forced in
for fifteen to twenty minutes, succeeded by hot air for ten minutes to
remove moisture, and cold air for about the same time to finally cool
the mass. It is adapted for cotton and textile goods as well as rags.
The disinfection of rags is now necessary under the new Act of the
United States Legislature. All rags used for paper-making must,
prior to shipment, be disinfected by one of the following methods : —
First, boiling the unbaled rags in water for half an hour ; second, expos^
ing them to the action of steam between 100° 0. and 1 15° C. for a similar
period ; third, exposing them for six hours in an atmosphere of sulphur
dioxide, made by burning 3 lbs. of sulphur to every 1000 cubic feet of
space ; fourth, exposing them six hours in an atmosphere containing
3 per cent, sulphur dioxide gas liberated from liquid sulphur dioxide.
By the third and fourth methods the rags must not occupy more than
50 per cent, of the total cubic space.
Disinfection of Air. — This is impossible except in confined spaces.
The germs of cholera and of a large number of other diseases are
known not to be carried by air, as an exposure to free oxidation in the
atmosphere (possibly to ozone in addition to common oxygen) and to
light soon destroys the majority of bacteria. In still air the organisms
sooner or later settle, especially if the air is damp and the walls are
moist. The number of microbes is least in pure external air. It is
greatest in places where the population is dense and the ventilation
defective. In inhabited houses the impurity is due to the products of
combustion and respiration. S. Merkel f states that air expired from
man and from animals even in a good state of health contains a minute
quantity of a volatile organic base, poisonous in a free state, but losing
its toxic effect when combined with acids. Brown Sequard, Arsonval,
and Wurtz X found that (a) vapour expired is alkaline ; (b) its toxicity
is not destroyed by heating in a closed retort ; hence they conclude
that the " esprit de corps" as it has been facetiously termed, has the
characters of an alkaloid. Animals confined in a space from which
the carbonic acid produced by respiration is continually removed die
long before the oxygen is consumed, although nitrogen is not poisonous.
In inhabited districts the air contains, in addition to micro-organisms,
fragments of carbon, of hairs, fibres of tissues, particles of starch, pollen
granules, epithelium, &c. These can be removed by filtration through
cotton wool, also in great part by passage over damp surfaces, or by
* Patent No. 7,735, 1894. t Archiv. f. Hyg., vol. xv., p. 1.
X Acad, des Sciences, Jan., 1888.
246 DISINFECTION AND DISINFECTANTS.
subsidence. Breath is ordinarily free from microbes, and sewer gas
contains exceedingly few. In both tbese cases the freedom from
germs is due to the subsidence on the damp surfaces present.
Prof. Klcbs remarks* that the cause of malaria is probably a specific
organism. From the air of malai-ial districts aspirated through suit-
able apparatus he obtained organisms about 0'95 micro-millimetre in
diameter, capable of producing malarial fever on inoculation. He
proposes the name Bacillus malarice for them. They are developed in
the presence of free oxygen, hence are aerobic. The subject has been
more recently studied at some length by North. In addition to the
apparatus for the disinfection of air already alluded to, there are a
vary large number of other inventions, of which the following is a
summary : —
For Sewer Gas. — Keelin's apparatus : the air is passed through gas
furnaces, t Eecent experiments with refuse destructors have, however,
established the fact that, although a comparatively low temperature is
sufficient for killing micro-organisms, a temperature of at least 1250° F.
is essential for entirely destroying any noxious vapours.
Vaporisers. — 1. In M. Godin's vaporiser the fluids are poured on a
porous stone on a stand heated by a lamp. J
2. An inlet ventilator in the wall of a room 6 ft. from the ground ;
the air entering horizontally is deflected through a short tube into
a well containing a disinfectant; and the charged air then passes
upwards into the room.§
3. Strips of linen are stretched on a series of frames radiating from
a central hinge, and are syringed with a disinfectant (or it is simply
poured on them) so as to expose a large surface. The whole apparatus
is enclosed in a case for carriage. ||
4. Barlow's exhausting ventilator IT is similar, but contains filters of
antiseptic wadding, and heating chambers for sterilising the air at
the outlets.
5. Bristow Hunt ** draws the ventilated air through a coil heated
by an ordinary stove. This apparatus is recommended for sewers,
cesspools, holds of vessels, «fec., but is open to the following objec-
tions : — (a) If the air passes rapidly, there is danger that the central
parts of the current will pass without being sterilised, on account of
the bad conducting qualities of air ; (6) the air so ti'eated is rendered
unfit to breathe ; (c) the coils, if narrow, become clogged and coated ;
(d) they are uncertain in action, depending on the working of the
• Atti della R. Acad, dei Lincei^ vol. vii., 1879.
t Lancet, 1888, vol. i., p. 486. t Chem. and Drug., vol. xxv., p. 89.
§ Brit. Med. Juurn., 1889, vol. xi., p. 771. II La7icet, 1889, vol. xi., p. 121.
IT Patent No. 194, 1878. ** Patent No. 1,321, 1878.
PRACTICAL METHODS. 247
stove ; (e) if made of firebrick flues or fireclay tubes, instead of iron,
they are easily broken in stoking, stirring, or cleaning; (/) they have
been known to cause fires by passing near woodwork. Nevertheless,
a method of this kind is cleaner, cheaper, and more effectual thau
any chemical disinfection for constant use.
6. Water or a disinfecting fluid flows in a thin film over rods or
metal-gauze tubes into a lower receiving tank from which the liquid
is pumped up again into an upper receptacle. The air to be purified
is guided by louvre plates or shutters over the wet surface.*
7. J. S. Mur t draws the air through revolving drums with opposing
slots, dipping into disinfecting fluid.
8. J. F. Johnson I proposes to use a rapidly revolving fan which, by
means of peculiar paddles, disperses the disinfectant as spray through
the current of air. This is a good apparatus where the motive power
can be obtained.
9. C. C. Leathers § also by means of a fan draws air through sawdust,
tow, (fee, impregnated with disinfectant.
10. W. H. Spencer || suggests the use of an open water-bath carrying
a porcelain pan containing eucalyptus or other oils which is heated
by a lamp underneath, and adjustable as to height above the flame.
11. Mr. W. Key's screen U is formed by stretching thousands of cords
of suitable material from ceiling to floor, interlaced with horizontal
copper wires stretched tight so as to form a flat surface like coarse
cloth. Water trickling down washes the air which passes through the
minute holes in the screen. Experiments done in a dense fog showed
that no fog passes through, and that the air thus purified is bright,
clear, and free from odour. In the case of dust the results were not
so satisfactory. A non-corrosive disinfectant or deodoriser could be
added to the water. If all the air could be made to pass through
such screens in sufficient volume, it would probably be one of the best
methods.
12. Kingzett** suggests a wick with one end embedded in a block
of plaster or other absorbent substance, the other dipping into a
reservoir of a disinfectant so that the evaporating surface is increased.
This device is also suggested as a means of supplying liquids to
surgical dressings or bandages.
Water for drinking and cooking is in London and several large
towns supplied of very indifferent quality. As obtained from deep
wells it has been naturally filtered, is free from germs, and almost
* J. Stanley, Patent No. 3,705, 1880. + Patent No. 2,781, 188.3.
t Patent No. 5,379, 1883. § Patent No. 22,258, 1881.
II Patent No. 8,629, 1891. TT Hygiene, May 13, 1893.
** Patent No. 3,830, 1893.
248 -
DISINFECTION AND DISINFECTANTS.
devoid of organic nitrogenous matter (which has been oxidised into
nitrates), but is of considerable hardness. River water is stored in
settling tanks, where, by oxidatfon and subsidence, the microbes are
mostly removed (see p. 15) ; then it is filtered by two methods —
(1) Natural filtration ; large reservoirs are dug parallel with the
banks of the river, being filtered through the ground in transit.
(2) Artificial filter beds, composed of layers of sand, gravel, and stones,
through which the water passes into the mains. In most districts it
is intermittently delivered into house cisterns ; some have a constant
supply (see p. 237).
feit/jifi/^ ?* !'
Fig. 23.— The Equifex Water Heat-steriliser.
Occasionally the water supplied is turbid, showing that the filter-
beds are not acting properly; it always contains micro-organisms,
greatly reduced in number, and usually non-pathogenic. It may also
be contaminated on its way to the consumer, from the ground through
leaky joints in the pipes (even full pipes carrying a current of water
will draw in surface drainage from the soil) or from the atmosphere
in the cisterns. Absolute safety can only be attained by boiling, or
by filtration through a Pasteur-Chamberland filter. A temperature
of 100° 0. does not kill all the germs {Tyndall, Koch, and others)
unless continued for a long time; hence it has been proposed to
sterilise water by heating under pressure.*
* Society Geneste, Herscher & Co., Paris. J. Y. Johnson's Patent No. 2,051,
Feb., 1891. Also J. Soc. Chem. Ind., May 31, 1892.
PRACTICAL METHODS. 249
Under the name of Equifex water heat-sterilisers, the Geneste-
Herscher patent has been recently introduced into this country. It
is shown in Fig. 23, and continuously sterilises water, and cannot
work unless the temperature for which it is set is applied for the
necessary time.
This control is effected by means of a valve which only lifts and
permits the passage of sterilised water at the necessary pressure and
temperature. The sterilising vessel is kept for fifteen minutes at the
required temperature, and by means of a cock the discharge pipe is
then opened. The capacity of the sterilising vessel and its discharge
orifice, and the pressure for which the safety valve is set, determine
the minimum time in which the vessel can empty itself; and the
control valve ensures that no part of this time can be occupied in
passing water below the desired temperature.
By allowing the sterilised water to heat the incoming water,
economy is effected, and the sterilised water may be delivered within
2" to 3° C. of the temperature of the service water. The high pressure
at the same time prevents the loss of dissolved gases, except in so far
as they re-act with dissolved organic matter on the water, and reduces
to some extent the precipitation of dissolved salts. The sterilised
water is passed through sand, and is discharged from the apparatus
cool. The course taken by the water is shown in the diagram, in
which the feathered arrows represent sterilised, and the others un-
sterilised, water.
The form shown in the diagram is that of an apparatus used in the
operating rooms of hospitals, and supplying about 8 gallons cold and
8 gallons hot sterilised water per hour. When heated by gas it
consumes about 45 cubic feet of gas per hour.
KUhn of Paris uses a similar sterilising plant for beer and other
organic liquids.*
Boiled water is not palatable ; filtration afterwards aerates it and
restores the proper taste ; hence, as it is proved that boiling does not
completely sterilise, boiling first and filtration afterwards through a
good and clean filter may be recommended. Water after boiling must
be kept in very clean vessels, and should not be exposed to air long
before drinking, as the multiplication of bacteria goes on far more
rapidly even than in unboiled water. f Boiled water may be artificially
aerated with carbonic acid in a gazogene apparatus. Dr. Altehoefer's
suggestions as to the use of hydrogen peroxide have been already referred
to (p. 85). Water in cisterns with constant supply lying stagnant
while families are away for the holidays may be a source of danger.
• Joum. Soc. Chem. Ind., 1894, p. 1133.
t Miquel, Analyse Bad&rioL des Eatix, Paris, 1891, p. 146.
250 DISINFECTION AND DISINFECTANTS.
The recent report of the Royal Commission on Metropolitan Water
Supply (1893) has drawn attention to the present unsatisfactory nature
of our bacteriological knowledge of river waters. Although there are
abundant opportunity for pathogenic organisms to enter the Thames,
hitherto investigators have failed to detect their presence in the water
supplied by the London companies. This result may be partially due
to the filtration which the water receives, but is probably mainly to
be attributed to their rapid attenuation and death when introduced
into a river water containing numerous non-pathogenic organisms.
It must not, however, be forgotten that the fate of these pathogenic
organisms has not been properly studied, and it is quite possible that
they may be present in such filtered water in a modified form, and
capable of giving rise to the original pathogenic forms so soon as they
are brought into a suitable medium. It seems, therefore, essential
that adequate precautionary methods of boiling and filtration should
be adopted by householders in towns possessing a river-water supply,
especially in warm weather and when there are any indications of
epidemic disease.
Preservation of Timber. — Although not strictly hygienic, attention
may be drawn to the use of antiseptics for preventing the decay of
wood. Two methods are in use : in the first, hydraulic pressure is
employed for injecting the preservative liquid into the lower end of
the log; in the second, the liquid is drawn in by vacuum pumps at
the upper end, the logs being encased at the end by india-rubber or
leather. These processes equally saturate the tissues, if thoroughly
cai'ried out, with the antiseptic, and prevent the penetration of the
disintegrating mycelium of fungi such as Merulius lachrymmts (dry
rot). The first method is the quicker. Either of them presupposes
the driving or sucking out of the natural juices, and replacement of
them by the antiseptic solution. Both of them are analogous to the
injection of corpses by preservatives.
Copper Sulphate (Kyanizing) was the earliest agent used, and is still
found eflfectual, although the corrosion by galvanic action of any iron
nails, screws, or bolts embedded in the wood is a serious disadvantage.
Mercuric chloride is precluded by the expense.
Creosote Oils are now commonly used. Well-seasoned timber is
placed in a vessel so constructed that a more or less perfect vacuum
can be obtained by an air-pump. The creosote oil, previously heated
from 35° to 50° C, is allowed to enter the exhausted receiver, and pres-
sure is then applied by pumps in order to efiect the better penetration of
the antiseptic fluid. In S. B. Boulton's improved process, the exhaus-
tion is continued after the entrance of the creosote, which is heated to
a temperature somewhat above 100° C. By this method the moisture
PRACTICAL METHODS. 251
contained in the pores of the wood is volatilised and removed by the
pump, and the oil subsequently penetrates the wood very thoroughly.
A great advantage of this process is that wet timber can be at once
treated without being previously seasoned. The amount of creosote
oil taken up by the timber varies considerably, but is usually about
1 gallon per cubic foot of wood. The smell of creosote oil is much
disliked by the lower animals (white ants, <fec.), while certain of the
constituents have a powerful antiseptic action. S. B, Eoulton and
Ooisne, on behalf of the Belgian Government, have proved that in the
course of a few years the tar-acids (phenol, &c.) in railway sleepers, &c.,
completely disappear by dissolving and by volatilisation, whereas the
semi-solid constituents, such as naphthalene, and the higher boiling
oils (above 315° 0.) remained, and could preserve the wood for sixteen
to thirty-two years.* Hence the phenoloid bodies of high boiling
point and slight solubility are probably of more value for creosoting
timber than carbolic or cresylic acids themselves. But the lower
phenols are doubtless of value in coagulating the organic matter
present in the sap, and should be present in creosote oils in sufficient
quantity to effect this.
* Allen's Commercial Org. Analysis, 1886, vol. xi., p. 552; S. B. Boulton, Froc.
Inst. Civ. Engineers, M&y, 1884.
252 DISINFECTION AND DISINFECTANTS.
CHAPTER XIII.
PERSONAL AND INTERNAL DISINFECTION—
POOD PRESERVATION.
Personal Disinfection : Sachets and Lockets practically useless — Cleansing the
Hands — Soloids — Gloves — Caustics — Snake-Bites — Burns and Scalds. Disin-
feotion of Cavities of the Body : (a) By Washing out— (6) By Spray — (c)
Gargles — (d) Injections of Gases or Vapours — (e) Inhalations. Antiseptic
Dressings : Sulphocarbolate of Zinc — Salufer Cubes — Sozal — Gauzes and
Wools — Antiseptic Paper — Rinsing Surgical Instruments. Hypodermic In-
jections. Antiseptic Soaps : Mouth Washes — Ointments. Respirators :
"Sanitary Wool" Clothing. Internal Disinfection: Charcoal — Sodium
sulphethylate — Chlorinated Soda— Oxygen — Sulphides. Internal Antisepsis :
Phenol — Creosote — Essential Oils — Mineral Waters — Acids — Sulphuric Lem-
onade — The Vienna Mixture — Betol, &c. — Quinine — Benzosol — Phenosalyl —
Vaccination. Preservatiox of Food : Causes of Change in Foods — (1)
Oxidation — (2) Reduction — (3) Metallic Contamination — (4) Organisms —
Methods of Exclusion of the Latter — Drying — Smoking — Necessity of Proper
Cooking — Curing by Wood Vinegar — Danger of Poisoning by Stale Fish.
Infection by Milk : Tyrotoxicon in Cheese, Milk, &c. — Infection of Food
by Bacteria in Air — Precautions. Preservation by Cold : Does not Kill all
Bacteria — Downward Draught — Methods of Freezing Meat — Large Refriger-
ators — Hydrocarbonic System. Preservation by Chemicals : Not Successful
— Sulphites, &c. Preservation by Heat : Canning Processes — I. Chloride of
Calcium Process — II. Aberdeen Process — III. Jones' Vacuum Process — IV.
Salzer's Baltimore Process — V. Budenberg's Steriliser — VI. Hartmann's
Method. Milk : A Common Vehicle for Contagion — Precautions — Heating
under Pressure — Preservatives. Condensed Milk : The Anglo-Swiss (Borden)
Process — Hooker's Cream Milk — Condensed Beer. Butter : Conditions affect-
ing Rancidity. Cheese : Aseptic Wrappers — Pickling and Cleansing Grain.
Bread : A Means of carrying Infection.
PERSONAL DISINFECTION.
Thk "last line of defence" includes the precautions taken by the
private individual. These may be considered to include cleanliness of
the home, cleanliness of the person, and purification of the clothing.
The first and third have been discussed, and it has already been
pointed out that individual immunity cannot be ensured by carrying
about the person camphor, aromatic vinegar, eucalyptus, or other
chemical substances, which in former times found favour as charms,
since these agents cannot reach an effective proportion in the atmo-
sphere. Many devices of little value have, however, been patented
for personal protection in even recent years. Thus Woodthorpe and
PERSONAL AND INTERNAL DISINFECTION. 253
others* suggest an ingenious arrangement like a vesta-box, with a
sliding perforated case, to be kept in the pocket, and a mixture of
bran 4 ounces, camphor 1 ounce, eucalyptus oil 2 drachms, hydro-
naphthol 1 drachm, carried in a linen sac, has been seriously
recommended to ensure wearers against infection in houses.
In fever cases it is now generally customary to sterilise the hands
by washing in a 1 per mille solution of mercuric chloride with a little
salt and hydrochloric acid (p. 138), and rinsing them with plain water
before washing with soap. In cases of very great danger the clothes
are afterwards disinfected by steam. Notwithstanding the fact that
many other antiseptics have been proposed for the hands, mercuric
chloride seems still to be the best. A few ounces are quite sufficient,
and should not be diluted beyond 1 in 1,000. The same solution
should also be used by nurses and attendants when leaving the room ;
a convenient way of preparing the solution is to dissolve one " soloid "
in a pint of water, taking care to stir well till all has dissolved. One
of the soloids in a pint of water makes a 1 in 1,000 solution. They
are characteristically coloured and shaped to avoid mistakes. In-
fectious matter is particularly liable to remain under the nails.
It is well known that any cut or abrasion of the skin when handling
septic matter inevitably causes blood-poisoning, which, if not fatal,
leaves dangerous after-effects ; also that specific diseases can be inocu-
lated in the same way. Waterproof gloves are manufactured for
operations involving such risk, but as they very much deaden the
delicacy of touch, they are seldom used. If a cut or wound has been
accidentally produced, cauterising with nitrate of silver, nitric acid,
phenol, permanganate, or osmic acid is frequently recommended, but the
eschar left is often very painful and troublesome to heal, besides not
being thoroughly safe against inoculation. Covering with lead or court
plaster, or with collodion ; painting with iodine or iodoform tincture ;
thoroughly drying the cut and painting with a solution of Stockholm
tar or Burgundy pitch in alcohol, ether, or acetone, are among the
other treatments suggested. None of these methods give absolute
immunity, so that, in case of accidental puncture during a post-mortem
or operation, or in handling contagious matter such as dead meat,
skins, or evacuations, it is probably safest to wash immediately with
mercuric chloride, dry, and at once cauterise, and thus combine the
two precautionary measures. "When, unfortunately, the abrasion has
not been noticed at the time, this treatment should still be resorted to.
Afterwards, hypodermic injections of an antiseptic have been recom-
mended, and cinnamic acid, styrol, phenyl-propionic acid, /3-naphthol,
and betol are used for this purpose ; phenol or any other reagent
* Patent No. 2,770, 1891.
254 DISINFECTION AND DISINFECTANTS.
which coagulates the blood is of course inapplicable. For ordinary
bites and scratches similar treatment may be adopted ; the part should
be afterwards protected by antiseptic gauze or wadding, iodoform
powder, or, failing these, by lead plaster, an ointment, or flour paste.
Snake-bites are considered to owe their virulence to an ill-defined
poison of an albuminoid nature (a " leucomaine," Selmi and others),
or to the crystalline cobric acid of Blyth. Filtration, which removes
micro-organisms, does not afiect the potency of snake-venom. Hypo-
dermic injections of diluted ammonia, after sucking out the poison
(it is almost inert internally), seems the best remedial treatment.
Burns and scalds are liable to septic poisoning if the epidermis is
broken, so that they also should be protected, but not cauterised.
Wasp-stings and insect-bites have caused death. The best remedies
are liquor plumbi subacetatis (p. 134) or Goulai'd's extract, and the
old-fashioned hartshorn and oil.
Disinfection of Cavities of the Body. — Cavities of the body, such as
the lungs, larynx, nasal passages, throat, urethra, bladder, and uterus,
are peculiarly liable to the attacks of microbes, causing inflammatory
and purulent conditions, and even absorption and specific diseases.
Several modes of treatment are in use, and have been several times
alluded to in the chemical section. They may be thus summarised : —
(a) Washing out by inflow and outflow tiibes with lukewarm water,
then with a weak solution of an antiseptic, which should not be one
with a strongly poisonous action on the system. Phenol, resorcin,
and mercuric chloride have been absorbed with dangerous, and even
fatal, effects. Iodine is very irritant. lodol has been recommended,
likewise betol and phenyl-propionic acid.* Salicylic acid is dangerous,
irritant, and not effective. A solution of silver nitrate in distilled
water has been tried with great success : the objection to it is that if
weak (1 in 1,000) it is almost wholly precipitated by the chloride of
sodium in the fluids of the body, and if stronger (1 in 200) it has on
some occasions caused sloughing. Sulphocarbolate of zinc, 1 in 1,000,
has the advantage of being mildly astringent, and seems to be safe.
A sulphocresylate would probably be still safer, and is a stronger
antiseptic. Alumnol (p. 179) is a useful and powerful astringent.
Glycerine is irritant to mucous membranes, but it is useful when it is
necessary to keep surfaces moist. On boric solutions see p. 101. A
number of the newer antiseptics are advocated for this special branch
of antisepsis, but they await more extended and impartial surgical
trials, as many of the earlier statements have not been verified by
recent experiments.
(6) Spraying. — Any of the former may be used in the form of spray,
* Klein, in Stevenson and Murphy's Hygiene, p. 261.
PERSONAL AND INTERNAL DISINFECTION. 255
the advantages being that stronger solutions may be used, that only
the affected parts are treated, that the irritating and depressant action
of large volumes of water are avoided, that a local refrigerant effect
may with safety be produced, that much less of the medicament is
required, and that the action can be watched, and the process repeated
with facility and without shock. The various spray-producers nearly
all act on the same principle ; a current of air is blown by an india-
rubber ball, with a second ball to render the blast steady, across the
narrowed orifice of a vertical tube dipping into the liquid in the bottle.
The strength and fineness of the spray are regulated by the relative-
size and position of the orifices, and the amount of liquid delivered is
known by the graduations on the bottle. The use of chlorine water,
with or without cocaine hydrochloride, has already been alluded to
(p. 59), and boric sprays are frequently used for the throat. Solutions
in ether were recommended by Philip Sterne, as far back as 1767,*
as antiseptic spray. Sprays are much used in Vienna on the ground
that they more easily penetrate parts covered with hair — e.g., mercuric
chloride, 1 to 2 per cent,, for mucous membranes, and chrysarobin,
10 per cent., for mycosis of the skin, f In hooping-cough, 2 per cent,
resorcinol in water, sprayed on the nose, pharynx, and larynx every
two hours, is said to give speedy relief.
(c) Gargles are a form of washing out only applicable to the throat.
Honey and borax, tannin, and alum have been used from time im-
memorial. This method is easily used by unskilled persons, but is
inferior to that of spray, as there is no certainty that the parts affected
will be reached. It is evident that no drug which will be poisonou»
if swallowed can be employed.
(d) Injections of Gases or Vapours. — It is a familiar fact that if
an abdominal cavity be wounded, septic poisoning and peritonitis is
almost certain to supervene, and that washing out may be dangerous,
owing to the intense irritation, and may even cause the above
disastrous result. In these cases spraying is also interdicted. Life
has frequently been saved by gaseous injections, and sulphur dioxide
seems to be the best remedy to employ. This is most readily obtained
by blowing a current of air through a tube containing some fragments
of sulphur, and allowing the gas produced to enter the cavity. The
part of the tube containing the sulphur is heated by a spirit lamp,
taking care that the end of the tube is kept cool. Blowing air through
a saturated solution of sulphurous acid or through a mixture of a
sulphite with acid is inferior to the above, as the quantity delivered
is uncertain. Liquefied sulphurous acid from a Boakes' bottle cannot
be used for this purpose, as the cold produced is intense and would
• Advice to the Consumptive. J Pharm. Jcum., voL xxi., p. 1040.
266 DISINFECTION AND DISINFECTANTS.
produce shock. Unfortunately sulphurous acid, by being absorbed
into the system, is recorded to haye produced fatal effects in one or
two cases. Baxter experimented specially on its effect on the virus
of peritonitis * with favourable results. Chlorine, bromine, and iodine
vapoui's are irritant and dangerous. Many others, such as chloroform,
ether, phenol, &c., are excluded by their narcotic action. Iodoform
vapour has caused poisonous effects. Carbonic acid is very soothing,
and rapidly subdues inflammation, but for this purpose the gas must
be thoroughly washed. It is only a feeble antiseptic, but would be a
better medium for other antiseptics, such as eucalyptol, than air.
(e) Inhalatiotis. — Chloride of ammonium is beneficial in bronchitis
and asthma. The simple breathing of the vapour of vinegar and hot
water also gives relief. Koch proved that a number of essential oils
when inhaled with steam are inhibitory to tubercle, f
Antiseptic Dressings usually include cotton-wool, wood-wool, or
gauze, which act as germ excluders ; they are [kept moist with
diluted soda chlorinata (p. 63), or with boric acid solution (p. 99) ;
sometimes phenol 2\ per cent., or mercuric chloride 1 in 1,000, are
used, but they are liable to produce ill effects on absorption. A large
number of other preparations have been already described in the
chemical section. Sulphocarbolate of zinc is one of the best. There
is a great advantage in changing the agent every few days ; even the
most innocuous are liable to become irritating if continuously used.
Diluted cresol and Sanitas fluid are useful in rotation with boric and
with chlorinated lotions. Glycerine is objectionable. Salufer cubes
(see Silicojluoride, p. 79) are portable and convenient. One cube
dissolved in a quart of water is used for dressings, or with a pint of
water for washing the hands. Sozal, aluminium sulphocarbolate, is a
strong astringent and antiseptic lotion (p. 158). Diaphtherin (p. 193)
in 1 per cent, solution has been much used in Germany. Tichborne
recommends J zinc sulphite as non-poisonous and not irritating.
Gauzes and Wools are described under iodoform, boric, and salicylic
acids, and zinc-mercuric cyanide (p. 142). Hydronaphthol gauze (p. 179)
has recently been much praised. Salicylic gauze is irritating. Thymol
or eucalyptus gauze would seem to be the best and safest. Benzoated
gauze, 5 per cent, has also been recommended.
Mr. Duquaire, of Lyons, has invented an ingenious antiseptic paper.
The material is asbestos with about 5 per cent, of ordinary paper pulp,
worked into soft paper and soaked in a petroleum-benzene solution of
beeswax. The solvent having been evaporated off in the open air, the
* Appendix to the Report of Med. Off. of the Privy Council, 1875.
t Marshall Ward, Journ. Soc. Chem. Ind., 1893, p. 943.
Z Brit. Med. Journ., 1890, p. 1064.
PERSONAL AND INTERNAL DISINFECTION. 257
tissue is ready for use. When required it is set on fire, and is so
made aseptic, and may be employed at once for dressing wounds.*
Unfortunately many of the antiseptic wools and dressings met with
commercially are of uncertain composition, and insufficient attention
has hitherto been paid to the importance of storing these articles in
such a way that the antiseptic present shall not be volatilised.
In France their sale, except by duly qualified pharmacists, is for-
bidden, but the question does not seem to have been discussed in
England.
Surgical instruments must be rinsed in a disinfectant which does
not corrode steel ; the various cresol preparations are much used for
this purpose. Those that turn turbid with water have the disadvan-
tage that the instruments cannot be so well seen (see p. 163). A good
preparation seems to be potassio-mercuric iodide, 1 in 4,000, or two of
the soloids to a pint, for hands or instruments.
Antiseptic Hypodermic Injections. — Several of these have been
much employed recently in France, particularly for phthisis; the
basis is olive oil, and all the ingredients are carefully sterilised by
heating to 120° 0.
Picot uses guaiacol 5, iodoform 1, olive oil to 100 ; Morel-Lavallees'
solution consists of eucalyptol 12, guaiacol 5, iodoform 4, olive oil
to 100.
Also solutions in olive oil of creosote 1 in 15, and eucalyptol 2 to
4 in 10 have been suggested.!
A number of mercurial compounds are used specially in syphi-
litic affections. They have been already enumerated and described
(p. 143).
Antiseptic Soaps. — The incorporation of a suitable antiseptic with
soap has long been recommended by medical men as being a con-
venient method for ensuring a regular use of an antiseptic. Coal tar
was one of the earliest materials used in this manner, and coal-tar
soaps, containing, however, mainly the phenoloid derivatives of tar, are
frequently employed. At the present time many other bodies are
utilised. The Sanitas Company since 1888 have incorporated their
" Sanitas fluid " with an ordinary soap, and advocate this preparation
for a variety of uses. These soaps are prepared as follows : — Resin or
crude turpentine is dissolved in alcohol, and sufficient potash added
to saponify the resin, and to leave an excess to combine with some
fatty acid which is subsequently added in alcoholic solution. Soap,
essential oils, or any disinfectant can also be added at the same time,
and the alcohol recovered for a second operation.
* Chem. and Drug., 1890, p. 36.
t Vicario, Amer. Druggist, June 15, 1891.
17
258 DISINFECTION AND DISINFECTANTS.
The Jeyes' patent covered the use of gas tar from which the light oil
has been distilled off. To the heavy oil an equal weight of caustic
soda and twice its weight of cocoanut oil are added, and the mixture
saponified in a jacketted pan. The addition of rosin, sulphate, and
carbonate of soda is also provided for, if deemed desirable. Quibell's
disinfectant soap and powder belong to this class ; they are made from
a liquid which seems to be a mixture of cresol and pine oil.* Calvert's
carbolic soap and Wright's coal-tar soap have long been recognised as
proprietary articles. The manganates have also been suggested for
rendering soap antiseptic. The salts must be mixed with the cold dry
soap. They cannot be recommended, as besides being poor disinfec-
tants, they are liable to leave a brown stain on the hands.
Eucalyptus, thymol, and terebene soaps are very pleasant prepara-
tions, and are, of course, antiseptic, but only feebly disinfectant.
Terebene and glycerine jelly decrease inflammation. Perhaps more
satisfactory than any of the foregoing are those soaps which contain a
salt of mercury, of which mercuric iodide is the best (p. 141). It is
dissolved in potassium iodide, and added to the soap in the proportion
of from 1 in 10,000 to 1 per cent., according to the purpose. Resorcin
and salicylic acid soaps are used by Hebra in his clinic at Vienna, and
are said to be powerfully bactericidal. Max Jolles has recently shown
that ordinary soaps without any added antiseptic have marked disin-
fectant properties.
Mouth washes and Tooth powders. — These are too numerous to be
discussed here. They are chiefly empirical mixtures which owe their
reputation to custom or advertisement. Some people use only water
with a little soap in it to clean the teeth, but it is of advantage to
assist the friction with a powder, and also to use an antiseptic which
will penetrate the crevices which cannot be reached by the brush.
Wood-charcoal powder is excellent, but rather disagreeable. The
best is said to be Areca nut ; it should not be used constantly, as it is
apt to scratch and wear away the enamel. Prepared chalk is the best
foundation for tooth powders, as it neutralises any acid, and being
softer than the enamel, it polishes but does not scratch. Powdered
myrrh, Peruvian bark, quinine, and other ingredients are frequently
added. Honey, borax, varioiis scents, such as orris and rose, are
among other substances which are commonly found in dentifrices.
As a mouth wash, where there is decay and the breath is offensive,
one of the best applications is chlorinated soda diluted to about
1 per cent., and used occasionally. It is not very pleasant, but it
removes all odour. Saccharin, sodium bicarbonate, oil of peppermint,
benzoic and boric acids, tannin, tincture of iodine, and tincture of
myrrh are also occasionally met with.
* Lancet, 1889, vol. xi., p. 701.
PERSONAL AND INTERNAL DISINFECTION. 259
Ointments. — With the exception of vaseline, which in itself is
decidedly somewhat disinfectant, and to a certain extent the prepara-
tions of glycerine such as " glycerinum saponatum," described at
p. 227, the bases of ointments are only antiseptic in the sense that
they exclude air and moulds and bacteria from the surface covered.
Otherwise their virtues are simply emollient, or depend on the drug,
such as mercury or zinc, which is incorporated with them.
G. H. Fox* recommends sulpholeate of sodium as having a remark-
able power of dissolving antiseptic drugs and of yielding them to the
skin.
Respirators for asthma, &c., are made of thicknesses of silvered
copper gauze. The air is warmed and filtered before entering the
lungs. Almost all microbes are removed by the moist sides of the
little tubes formed by the gauze, which has to be occasionally cleared
from the dust. Several patents have had for object the introduction
of a disinfectant into the respirator. Only one that is non-volatile
would be permissible, as the constant inhalation of any medicated
vapour would be injurious. Permanganate, charcoal, and various
tissiies have been tried, but Avithout success, as they obstruct the
breathing. Every arrangement for filtering air by the action of- the
lungs must obviously place an additional burden on the muscles of
respiration, and the supply of air will almost certainly be lessened.
Hence the use of respirators has become much less frequent. Tyndall
is credited with suggesting that the human frame should be encased
in cotton wool to keep out germs. Many of the patents are quite as
impracticable. Wool clothing comes near to this ideal, permitting
free egress to perspiration, while excluding dust and microbes. Its
film of air keeps the body warm, like a respirator. Pasteur, in 1879,
recommended cotton wool respirators for doctors and attendants in
fever wards, in the same way that Alphonse Guerin in France, and
Lister in England, protect wounds.
Internal Disinfection. — In the alimentary canal, and sometimes in
other parts of the body, there are always present large numbers of
micro-organisms, and it is probable that the process of digestion
itself may be assisted by certain microbes. Even pathogenic bacilli
•may enter in limited numbers without producing disease. They
are not destroyed by the gastric juice, but rarely survive in the
struggle for existence with the far more numerous non-disease-
producing organisms. They only produce dangerous results when,
multiplying beyond control, they penetrate the blood and tissues,
interfere with nutrition, set up irritation by their presence, or poison
the system by their products of excretion. If they are present
* Therapeutic Gazette, 1891.
260 DISINFECTION AND DISINFECTANTS.
largely in food, water, or air, it is impossible to exclude them from the
body, and equally impossible to kill them when they have entered,
since, as has been insisted on before, any chemical agent of suflicient
power to destroy the germs would also be noxious, or might even be
fatal, to the higher animal. All disinfectants must necessarily be
more or less poisonous.
The removal of bacteria may, however, be brought about by hasten-
ing their elimination by purgatives, or by entangling them and their
products by inert substances like wood-charcoal, which is known to
have proved most beneficial in indigestion and flatulency, states which
are probably due to, or at least intensified by, organisms promoting
abnormal fermentations. Charcoal biscuits are not so efiectual as a
large dose of fresh charcoal in water. Opinions difier as to whether
bacteria are eliminated by the skin in profuse perspiration ; there is
no doubt that the latter frequently gives great relief in fevers, &c.
Saline purgatives are specially indicated. One of the best for this
special purpose is sodium sulphethylate, which has been much used in
Prance, but rarely in England. The alcohol basis which it contains
renders it slightly stimulant and antiseptic. It is distinctly worthy
of an extended trial.
It has been hoped that oxidising agents like chlorinated soda,
peroxide of hydrogen, potassium permanganate, and even potassium
•chlorate would be capable of attacking bacteria in the alimentary
canal. But the last-mentioned passes right through the system into
the urine without change, while the others not only disturb digestion,
but are rapidly used up by the easily oxidisable organic matters
present — i.e., they act on the food before afiecting the far more stable
bacteria. Much was expected from hydrogen peroxide, but results
have been disappointing. An oxygenated milk, also an effervescing
water saturated with the gas under pressure, have also been intro-
duced, under the idea that the free gases would destroy bacteria.
Sulphuretted hydrogen water and sulphites were formerly given
with the object of destroying organisms. They are unpleasant, dis-
turb digestion, and do not seem to bring about the desired effect.
Internal Antisepsis. — Although it is impossible to kill the bacteria
within the body, it is quite feasible to hinder their growth and the
development of spores by an inhibitory or antiseptic treatment, and
so at the same time to lessen their irritant and poisonous action. If
the contents of the stomach were undergoing fermentation by the
action of yeast, &c., it would be quite possible to stop the process by
means of phenol, creosote, or an essential oil, with a dose so small as
not to injure the coats of the stomach. But the same dose would also
stop or at least impede salivary, pancreatic, and gastric digestions.
PERSONAL AND INTERNAL DISINFECmON. 261
Therefore these powerful agents, though occasionally given in capsules,
are not in general favour. It has been suggested in a previous chapter
that the use of condiments such as salt, vinegar, pepper, mustard, and
spices is really an instinct founded on their antiseptic action, since
many animals resemble man in this respect. The effect of mineral
waters, too, depends in a large measure on the antiseptic action of
carbonic acid, and not on the alkali, since soda water generally does
not contain soda.
It has been already pointed out that acids are antagonistic to most
bacteria (p. 69). Dilute sulphuric acid has been preferred in many
diseases, especially cholera, on account of the additional advantage of
its astringent action. Sulphuric lemonade, made by the addition of
the acid, which should be perfectly pure, to sweetened and sterilised
■water in quantities sufficient to give a marked, but pleasant, acidulous
flavour, may be employed freely, and according to all experience with
much benefit. Dr. Waller Lewis, the late General Medical Officer of
the Post Office, attributed excellent effects to the habitual and free
supply of a pleasant-flavoured sulphuric orangeade among the employes
of the Post Office during several cholera seasons. It is cheap and
innocuous, and is vefy likely to do much good. Although ordinary
lemonade contains citric acid, it is more costly, and is inferior to
sulphuric for this special purpose.
The Vienna mixture for choleraic diarrhoea consists of 15 drops of
aromatic sulphuric acid (sulphuric acid 1 in 12, with rectified spirit,
cinnamon, and ginger) to 1 ounce of sweetened water ; to this is often
added, under medical advice, 5 or 10 drops of ether and 5 drops of
laudanum. The mixture has been much used and highly thought of
in Austria, Germany, and France, and by the English Local Govern-
ment Board.
For intestinal antisepsis neither phenol nor creosote can be em-
ployed, being too poisonous and irritating. Betol, however (p. 179),
has been successfully used, the ]8-naphthol produced by its decom-
position being comparatively non-injurious. Resorcinol, thymol, and
sodium benzoate are sometimes used as internal antiseptics, but they
have mostly the same objection to their use as phenol. Sodium
sulphocarbolate (p. 158), on the other hand, is safe and is much
used.
Quinine and its source, cinchona bark, probably owe a great deal of
their power in fevers to their antiseptic action. None of the substi-
tutes for quinine are equal to it in general utility, and many of them,
such as kairine, have proved very dangerous.
Several of the derivatives of guaiacol, such as benzosol, have been
highly recommended, and are described under their respective heads.
262 DISINFECTION AND DISINFECTANTS.
Pheno-salyl (p. 200) is a good preparation for washing out the bladder
and urethra.
Vaccination. — Vaccination and other preventive measures of inocu-
lation are at present foreign to the scope of the present work, but may
properly be regarded as precautionary measures relating to personal
disinfection. Modern research seems to indicate that the toxines
produced by the micro-organisms of infectious disease are the natural
disinfectants for combating the disease, and there seems good ground
for believing that progress on these lines will be rapid in the near
future. The present absence of definite chemical knowledge as to the
nature of these remedies for phthisis, hydrophobia, diphtheria, and
similar diseases, renders the subject unsuitable for treatment here,
although their investigation from a bacteriological point of view has
yielded, without doubt, some of the most valuable and suggestive
results obtained in recent years.
Natural immunity is produced either by dissolved alexines or from
the resistance of the tissues, whilst acquired immunity is due to the
presence of modified bacterial products. Roux has shown that the
serum of animals vaccinated against cholera and pneumonia has no
antitoxic properties, although it is germicidal on the microbe. With
diphtheria and tetanus the antitoxin is properly so called, as it is
destructive to the toxines secreted by the micro-organisms.*
PRESERVATION OF FOOD.
Among the principal food preservatives are boracic acid (p. 99),
glycerine (p. 22G), salicylic acid (p. 198), bisulphites (p. 96), carbonic
acid (p. 104), creosote (p. 161), acetic acid (p. 225), and formaldehyde
(p. 220). The changes which food substances may undergo before
consumption may be classified under the following heads : —
Causes of Change in Food. — 1. By Oxidation. — This is comparatively
rare and slow in the absence of microbes. Dilute alcohol is trans-
formed into acetic acid by air when in contact with platinum black,
but the process is quicker under the action of the vinegar fungus,
Mycoderma aceti. As far as is known, simple oxidation never renders
substances injurious.
2. JBy Reduction. — The only reducing agent that could naturally
occur in this connection would be sulphuretted hydrogen, which would
involve putrefaction in the substance or in the neighbourhood, and
■would therefore presuppose the presence of bacteria. It has been
suggested that the peculiar taste of certain canned foods depends on
the reduction of the fluids by the metal, on the ground that its degree
* Buchner, Amer. Journ. Med.Sci,,J&n., 1895; Roux, Med. Week, Sept. 14, 1894;
Pagano, Brit. Med. Journ., Dec. 1, 1894.
PRESERVATION OF FOOD. 263
is out of proportion with the traces of metal dissolved, and that it is
caused with such extreme rapidity, as, for example, when an apple or
fish is cut with a steel knife. In this latter case the taste is often
imaginar}', as blindfold experiments with apples and fish show that
the majority of persons are unable to detect which was cut with clean
steel and which with silvei-. Of course if the metal is allowed time to
become acted upon, a ferrugiuous taste is imparted. Zinc gives a
different flavour. Magnesium gives none. Hence the cause would
seem to be the metal, not reduction. There is no evidence that a
slight reduction would be at all injurious. Sulphites and formalde-
hyde, if used for preserving, would cause some reduction in unstable
constituents of the food.
3. By Metallic Contamination. — Vegetable substances coming iu
contact with iron are blackened and their flavour spoilt. This has led
to the use of copper vessels for preparing jams and syrups ; even
pickles were formerly made in copper vessels. The employment of
this metal for vinegar or very acid juices is most reprehensible, as
even if the surface is clean, an unknown and often considerable amount
of metal finds its way into the food. Mainly through Dr. Hassal and
Messrs. Crosse & Blackwell, apparatus of wood, stoneware, and evea
silver and platinum have displaced copper in making pickles. Enam-
elled iron should be used for making jams. The presence of copper in
preserved peas has been defended on the ground that (a) it improved
the colour ; (h) being antiseptic, it increased the keeping properties ;
(c) it was not poisonous in small quantities, but acted as a bene-
ficial tonic. The best authorities regard it as irritant ; it is probably
cumulative, and it should certainly be prohibited. Lead may be
present from the solder, and Hehner has drawn attention to the fact
that almost all canned provisions contain tin in solution. Superior
goods are put up with oiled paper linings, so as not to come in contact
with the metal. The irritant efiects of some tinned goods have been
attributed to chloride of zinc, which had entered in the soldering;
this, and also the dropping in of particles of solder containing lead,
have been since prevented by a guard-plate underneath the hole, or
by the use of resin for soldering instead of zinc chloride. W. Reuss*
has noticed the presence of lead in preserves contained in tinned-
iron canisters. The latter were constructed by bending some sheet-
metal together, thereby avoiding contamination with lead by means
of solder, and hermetically sealed by india-rubber bands. He subse-
quently traced the lead to these bands, which owed their colour to red
lead. On examining red india-rubber bands of French, German, and
English manufacture, he found them to contain as much as 60 per cent.
. * Chem. Zeitung, 1891, pp. 1522 and 1583.
264 DISINFECTION AND DISINFECTANTS.
of red lead. Many of the india-rubber bands used for sealing pickles,
jams, meats, and preserves owe their red colour to sulphide of antimony,
and are free from lead, but antimony has not been found in the food
itself. In New York, glass vessels have been tried to overcome these
difficulties; but, owing to the expense, breakage, and unsightly
appearance of some forms of soups and meats, have not met v/ith
much success. For brawn and potted meats earthenware is used.
Its weight and fragility are the only disadvantages.
Attempts have been made to coat the inside of the tin with varnish,
paraffin, &c., but have not been successful.
If the inside of the tin be much discoloured, or if tinned fruits show
a strongly marked crystalline appearance on the interior surface they
are unsafe to be eaten. Any discoloration of the contents, or any
peculiar odour or taste, should also be distrusted.
4. By Organisms. — Yeast, moulds, and bacteria of all kinds can be
carried in the dust of the air, on to the surface of any exposed food.
There they develop their mycelium, which ramifies throughout the
substance and accomplishes fermentative and putrefactive changes.
It would be supposed, therefore, that exclusion of air and dust would
suffice to preserve changeable bodies. With this object receptacles
exhausted by an air pump and afterwards hermetically sealed have
been patented. Pasteur and Tyndall's experiment?, which proved
that air purified from germs by filtration through cotton-wool caused
no alteration in urine, beef tea, milk, or sugar solutions, showed
also that these must be previously collected so as to exclude the
microbe, or must be sterilised by sufficient heat. It is impossible,
however, to preserve most alimentary substances in the raw state
without the addition of spices or chemicals, because the air con-
tained in them, and the few germs which it is impossible to keep
out, are sufficient to bring about their decomposition. However,
eggs can be preserved for months by keeping them in a pan of lime
water, or by dipping them in a cream of slaked lime and water ; in
each case the shell is rendered impervious by a coating of carbonate
of lime, and the albuminous inner lining of the shell is coagulated
and rendered aseptic, as can be proved by breaking and examining.
Smearing with fat or varnishing gives a bad flavour. Paraffin wax
easily peels off", and is expensive. Fruit has been kept from decay by
a coating of melted wax, when gathered fresh and not quite ripe.
Jams are usually covered with parchment paper sealed down by white
of egg. This membrane does not necessarily exclude air, but its tiny
holes must be small enough to exclude bacteria and spores of mould.
Generally a disc of tissue paper is laid on the jam, when hot, as
an additional precaution. It will be found sometimes that mould
PRESERVATION OF FOOD. 265
has grown on the top of this, but has not penetrated to the pre-
serve.
Coating with glue, gelatine, or melted fat has been tried for meat
without success. Meat is preserved to a certain extent by membranes
such as sausage skins.
L. Smith, of Chicago,* proposes to store the goods in air-tight vessels
from which the air can be exhausted, while by a three-way tap
carbonic acid is admitted in its place. This gas is antiseptic, has
no eflfect on the foods or containing vessels, and does not alter the
flavour.
Drying alone is the subject of a large number of patents, differing
only in mechanical details. Expression of water and desiccation leave
the fibre and dried juices incapable of putrefaction, but the flavour
and digestibility are much impaired. Charqui, South American dried
beef, and pemmican are well known. Dried vegetables are manufac-
tured by several firms. Soup-tablets and desiccated soup are generally
made with vegetables and meat extract, with very little fibre ; many
of them are wholesome and palatable, and keep well in closed tins.
Smoking is accomplished properly by hanging up in peat or wood
smoke. The surface .becomes dried, and also impregnated with acetic
acid, wood spirit, and creosote. Although the two former eventually
volatilise from the food, the surface retains a good deal of the
creosote, and undergoes no change except that the fat in time
may become rusty or rancid. A great part of this rankness may
be removed by putting about half a dozen lumps of freshly-burnt, or
re-heated, charcoal in the water in which the meat is boiled. The
charcoal removes the odour, but does not thereby render the article
wholesome, hence the change must not have gone too far. Smoking
has only a surface preservative action, and does not reach the interior,
so that the ova of trichina, tapeworm, ic, remain undestroyed. In
countries like Germany, where smoked sausages are consumed raw,
or nearly so, the ravages of these parasites are frequently severe. In
England, where thorough cooking is the rule, such epidemics are very
rare. Still it must be remembered that neither di'ying, smoking, nor
salting secures safety against the ova of parasites. To save time, hams,
haddocks, «kc., are often cured by dipping in pyroligneous acid, or
crude wood-vinegar, with or without brine, or even by being merely
brushed over with this solution. Kippers and haddocks are often
prepared under most unsanitary conditions, and as the treatment is
often far from complete, may be a source of danger. Very slight
evidences of decomposition in fish are suflficient to indicate the possi-
bility of an extremely poisonous] product in the body of the animal,
• Patent No. 2,444, A, 1891.
266 DISINFECTION AND DISINFECTANTS.
SO that fish must never be trusted in. the same way as high game
and mutton sometimes are. The faintest trace of decomposition in
fish forbids its use as an article of food.
B. Pifiard* prepares an antiseptic liquid by burning wood in a
suitable furnace and conducting the smoke into a tube or chimney
through which steam is propelled from a boiler ; the vapours are then
condensed in a suitable apparatus. The woods employed vary according
to the nature of the food and the flavour it is required to impart. The
patentee uses oak for pork, peat for fish, birch for tongues, and so on.
The length of time during which the food is immersed in the liquor
varies according to the nature of the article and the strength of the
antiseptic. When the liquor is of a dark straw colour, the time is
from three to six days for pork, a few hours for fish, and one minute
for imported preserved meat, which is thereby much improved in
flavour and keeping properties.
It must not be forgotten that as, in the first instance, micro-
organisms settle on the surface of foods, such food may often present
a normal appearance, and consequently be passed by inspectors and
■others as suitable for consumption.
Milk has been shown to be a frequent source of danger, and many
epidemics have been traced to its pollution, either through the water
supply of the cows, carelessness in the dairy, or in the conditions
obtaining between the time when it is supplied by the farmer and
■when it reaches the house of the consumer. Vaughan has further
shown that in addition to the danger of milk containing pathogenic
organisms, under certain conditions tyrotoxicon, a ptomaine produced
by a non-pathogenic form, is produced which gives rise to summer and
infantile cholera. As the poison is destroyed by boiling, its absence
may be assured by this precaution. Vaughan has also demonstrated
its presence in cheese, ice creams, and stale fish.
Cold. — It has already been shown that most micro-organisms are
not killed by cold. Nevertheless, various methods of refrigeration are
largely employed for preservative purposes. In Russia and Canada
carcases are buried in frozen earth from November to May. Fish and
poultry are constantly brought to town packed in ice. Ships fitted
with refrigerating apparatus bring meat from Australia and America.
One of the earlier forms of cooling plant is the downward draught
method of Kent, in which the cooled air being denser descends from
the ice-chambers and passes round the meat. It has been found in
practice that it is not absolutely necessary that the meat should be
perfectly frozen, a low temperature approaching freezing point is all
that is required for temporary preservation. In Gamgee's process the
* Patent No. 21,305, 1891.
PBESEBVATION OP FOOD. 267
rapid evaporation of sulphurous acid, aided by pumps, produces intense
cold, circulating by glycerine and water through pipes' Liquid am-
monia is also used in a similar way.
At the Victoria Docks there are twenty-one refrigerating chambers,
holding at times 200,000 carcases of sheep. At Smithfield Market
the refrigerating space is equal to 250,000 cubic feet, in addition to
the cold rooms in the basement of the building. The walls and roof
are insulated by an inch of hair-felt between two thicknesses of deal
boards joined very closely and with an air-space separating them from
the building. The floor is rendered a non-conductor of heat by two
layers of deal separated by a layer of finely-divided charcoal. Re-
frigerating machinery on the hydrocarbonic system is erected in the
basement. In this system carbonic acid gas, produced by the com-
bustion of coal or otherwise, is forced by a pressure of several atmo-
spheres into cooled water. On removing the pressure by means of
reversible air pumps the gas escapes rapidly, thereby abstracting heat
from a reservoir of brine (which stands a low temperature without
freezing) ; the brine circulates by pipes throughout the building, and
also cools the inlets of fresh air. The gas is forced again into another
cooled condenser, and when the excess has been transferred, the
apparatus is reversed, and the gas escapes back again, cooling another
reservoir of brine, in the second vessel. By a couple, or a series, of
these twin vessels, and a system of valves for the brine tubes, the cold
is kept constant, using the same carbonic acid and the same brine.
The apparatus is safer in case of leakage or accident than those using
sulphurous acid and ammonia, and does not involve such high pressures
as when liquefied carbonic acid is employed. A leak is discovered by
the hissing sound, or by a light being extinguished when applied. It
is obvious that in case of emergency the solution of carbonic acid
could be used like the ordinary fire extincteur. Arrangements are
provided by which the temperature of the various sections of the
building may be regulated to requirements, and special precautions
have been taken for the ventilation of the building, and for changing
the air very rapidly if need be, so that in the event of a carcase going
bad from any cause, the risk of its tainting the rest may at once be
obviated.
Preservation by Chemicals has not hitherto been successful. Either
the food has acquired a peculiar flavour, or has lost a great deal of its
nutriment and digestibility with its juices, as in ordinary salting.
Sugar-curing aims chiefly at excluding air, as the antiseptic properties
of sugar are very feeble, but where it is employed for preserving
jams and candies, it is the heat that is the real agent, since a solution
of sugar boils at a much higher temperature than water. Protection
268 DISINFECTION AND DISINFECTANTS.
from air is also an effect here, since the viscosity opposes resistance
to the penetration of germs. Saltpetre, ammonium acetate, acid sul-
phate of potash, ammonium chloride, lactic, tartaric and citric acids,
&c., have appeared in several patents, but have not been successful.
When using these preservatives it is to be noted that (1) if the food
be directed to be merely dipped, or to have the antiseptic rubbed on,
so that it can be cut, washed, or rubbed off before cooking, the surface
only is kept sterile ; (2) if it were possible to permeate the whole mass
with the antiseptic, the result would be the presence of a quantity of
the chemical that would certainly be unpalatable and injurious to
health if frequently consumed.
Gamgee invented a chemical process to be iised before the death of
the animal. Having noticed that carbonic oxide when it combined
with the blood rendered it almost imputrescible, he caused the animal
to inhale this gas for two minutes. They were thereby rendered
insensible. After slaughtering, they were hung up in chambers filled
with the gas (produced by passing carbon dioxide from burning coke
through layers of red-hot charcoal), and containing boxes of charcoal
saturated with sulphur dioxide. After twenty-four to forty-eight
hours' exposure the treated meat kept for many months. The process
appears to have been unsuccessful on the commercial scale, owing to
the expense. Injection of various fluids into the veins has been also
a failure.
It is said that in the salt mines of Cheshire the atmosphere con-
taining salt dust preserves the miners against cold, rheumatism,
neuralgia, and infectious diseases, without being injurious to the
lungs, and that raw meat will keep for a very long time.* This
effect may, however, be due to the comparative absence of bacteria
in still air, as the salt mines are not artificially ventilated. In France
the use of boric acid, borax, and bisulphate of soda for the preservation
of food has been adversely reported upon by M. Nocard, and the Seine
Council of Hygiene have prohibited their use in consequence.
Preservation by Heat. — The conditions under which heat alone, or
heat with steam, will sterilise have already been discussed (p. 29).
Articles of food always contain moisture, so that the conditions
present here are heat and steam. While the exterior of a joint
reaches the boiling point, the interior does not attain that tempera-
ture, so that the germs or ova that may be present are not raised to a
sterilising temperature. In most canned meats it is probable that the
whole of the food is raised to the temperature of the water, and, when
of good quality, they are probably as wholesome, nourishing, and
digestible as meat that has been cooked in the ordinary way.
* Manley, Brit. Manuf. Industries, 1878, p. 10.
PRESERVATION OP POOD. 269
M. Appert, of Paris, in 1810, first introduced the process of heating
provisions in vessels which could be hermetically closed, so that the
steam should drive out the air and a vacuum be produced. This is
clearly seen by the fact that the ends of tins which are in proper con-
dition are concave, that they often collapse, and that there is an inrush
of air when they are opened. Unless these signs are observed, the tin
is bad and must not be eaten. All tins are examined in the warehouse,
and such as are blown, i.e., convex at the ends, owing to gases from
decomposition inside, are rejected. Collapsed or crushed tins (which
are sometimes offered cheap) are also dangerous, as in the sharp
bending of the tin holes are apt to be formed. There are three
principal processes for canning foods : —
1. The Chloride of Calcium Process. — The tins after being filled have
the lids soldered on, leaving a pin-hole for escape of steam. They are
immersed to two-thirds of their depth in a bath of calcium chloride
solution, which boils at a higher temperature than water, heated from
260° to 270° F. for one to three hours, and the hole closed by a drop
of solder.
2. The Aberdeen Process. — The tins are placed in a bath as before,
but they are entirely closed. During the heating they are raised at
times by a frame, opeiied to let out air and vapour, so that the tin
does not burst, closed again and the heating continued. This is re-
peated two or three times, according to the size and substance. The
pressure within is judged by the forcing out of the ends. Superheated
steam is used by some firms instead of salt baths ; it is rather more
difficult to manage, but leaves the tins clean. This process, which is
known by the tins having two or three blow-holes, presents the advan-
tage that more of the natural moisture and flavour are retained. It
has superseded the former process in Scotland, Australia, South
America, and New Zealand.
3. Joneses Vacuum Process. — The tins are packed quite full, and
soldered up except a small hole, with a little quill tube, in the top.
The bath contains ninety-six 2-lb. tins. Along the centre of the bath
runs a tube with twelve taps, each of which carries eight stuffing boxes
connected with the tubes. By a fan or pumps a vacuum is created,
and the bath is heated gradually to 212° F. The fluid in the tins,
under the diminished pressure, boils at about 100° F., so that the steam
and air are carried off" at a low temperature. After a time the exhaust
taps are turned off. The tins then contain no air, and are full of steam.
The cooking is continued for two hours at 250° F., letting ofiF the
steam occasionally as the pressure increases.
4. Salzer's Baltimore Process. — Meat is subjected to dry steam and
compressed in moulds, then wrapped in paper or other material, coated
270
DISINFECTION AND DISINFECTANTS.
PRESERVATION OP FOOD. 271
■with plaster of Paris, embedded in a heated fat such as suet or lard,
in a can or in metallic foil, with certain precautions.*
5. In Germany, and to a certain extent in Italy and France, the
dangerous and objectionable custom is prevalent of eating meat in the
uncooked state, simply smoked or pickled. Raw hams and bacon only
smoke-dried, Gotha sausages, and even chopped raw steak with bread
crumbs and onions are commonly consumed. This practice necessi-
tates that the meat in the markets should be rigidly inspected, and
hundreds of carcases are seized and destroyed. With the idea of
saving this confiscated diseased meat for food, W. Budenberg, of
Dortmund, has invented a flesh steriliser, in which the disease germs
are killed by steam under pressure.
It consists of a large iron cylinder, one end of which opens on hinges
and closes hermetically against packing. Steam at a pressure of half
an atmosphere (112° C.) is injected at the top, circulates round the
movable iron shelves on which the pieces of meat are placed, and
escapes to a condenser through a tube at the bottom, or can be led
into a fireplace to burn any unpleasant vapours from the meat. The
temperature can now be raised to 127° 0. by letting in steam of 2^
atmospheres ; after two or three hours' heating all germs of disease
are destroyed. The fat and liquor are drawn ofi" separately below.
The fat can be used, the liquor is thrown away. At a higher tempera-
ture the meat is much disintegrated and dried, but is still digestible
and fit for the food of animals, dog biscuits, <kc. The temperature of
the interior of the largest lumps of flesh, as registered by a maximum
thermometer, remains steady at some degrees over 100° C. The loss
of weight is from 40 to 50 per cent.
In some cases, where the apparatus is only used as a meat-steamer
to save large quantities of meat from being lost by putrefaction in
summer, it can be worked throughout at half an atmosphere of steam
pressure. At this lower temperature the meat is as juicy and savoury
as in ordinary cooking. The interior of the pieces reaches a tem-
perature of 100° to 120° C, so that it can be sold for eating without
hesitation. The inventor states that the sterilisation at the higher
temperature was found by experiment to be perfect.
6. G. Ilartmann^s process t dispenses with the use of antiseptics,
and consists of three steps — preliminary sterilisation, germinating
period, and final sterilisation. The first step consists in subjecting
the preserves to a temperature of 100° to 120° for a short time; the
second in keeping them for some days at a temperature of 20° to 30°,
when any germs which have not been destroyed in the primary
* Patent No. 11,988, 189'^. t Patent No. 14,601, 1892.
272 DISINFECTION AND DISINFECTANTS.
sterilising process develop. They are then completely destroyed by
a final sterilisation process.
7. Process for Preserving Organic Substances hy Formaldehyde. — The
remarkable antiseptic properties of formaldehyde are said to render
it a suitable substance to employ. Meat and similar substances are
immersed for a few seconds in an aqueous solution of formaldehyde,
liquids are mixed with ^-g-^xnr P^''* ^^ ^*- Solid substances may also
be exposed to the formaldehyde vapour. Considering the "minute
quantity employed, there seems not the slightest objection to its use ;
moreover, meat, vegetables, and similar articles of food, when treated
with it, do not lose anything of their appearance or freshness, or sufier
in any other respects.
Milk. — Bacterium lactis, the organism which turns milk sour, is not
the only one which finds a favourable place of growth in milk. Infec-
tion of difierent kinds apparently can be carried by it, and several
epidemics have been traced to this cause. Hence the strong recom-
mendations that milk should in all cases be boiled, and that dairies
should be kept scrupulously clean, and well-ventilated. All cases of
infectious diseases occurring on the farm must, under heavy penalties,
be instantly reported, and the supply of milk discontinued until the
case has been removed and the buildings properly disinfected. Milk
cans should be washed out as soon as possible after use, and finally
scalded with boiling water, and turned upside down, in a place free
from dust, to drain and dry ; then they should be covered till wanted.
Removing any stale smell by charcoal is not a safe proceeding, as the
odour is a sign that the cleaning has not been thorough ; in such a
case the can should be thoroughly steamed, and then washed. Water
from ponds or contaminated wells should never be used for washing
vessels that are intended for milk, as this has originated many cases
of typhoid, scarlet fever, and other zymotic diseases. Strongly smelling
disinfectants cannot be employed for dairies, since milk is so particu-
arly absorbent of odours. Probably peroxide of hydrogen would be
the best agent for this purpose, if it were cheaper. Formaldehyde is
now largely used in this country and Australia. It is to be regretted
that jets of steam are not more extensively used for cleaning milk
vessels ; it would be easy to fit up an apparatus for this treatment at
railway stations, where the cans could be systematically cleansed before
going to the farms.
Milk can be kept for an indefinite time by heating it under pressure
to 120° C, closing it whilst hot with corks or stoppers, and storing it
in a jool place. If exposed in a warm situation after this, the casein
is apt to undergo some molecular change, by which it clots into
granules, or even sets almost solid, but no putrefaction ensues. It
PRESERVATION OF FOOD. 273
does not usually pay to preserve milk ' without concentration, on
account of the bulk. The usual methods for milk-preservation may
be divided into two groups — (1) those based on the addition of a
foreign ingredient ; (2) sterilisation by heat.
1. Boric and salicylic acids, borax, formaldehyde, cane and milk
sugars, glucose, sodium carbonate, potassium nitrate, and glycerine
have been added. Some of these preservatives are obviously likely to
be prejudicial to the health of young children, and should not be
used.*
2. Bethell in 1848 patented a process for preserving milk, which
consisted in boiling it to expel all the air, and then saturating with
carbonic acid ; by this means, milk can be kept fresh for weeks.
Duclaux kept milk for five years in a vessel from which he had
previously exhausted the air and heated the contents to 120° 0.
Sterilised milk is now supplied, in many of the larger towns, in
bottles which are hermetically sealed. Such sterilised milk is valuable
for voyages and for invalids.
In GromAJoaldJs patent sterilising apparatus for fluids f the fluid is
sterilised in the vessel used for storage ; it can be closed without
admitting air, and allows the vessel to be filled to any desired height
without any risk of the fluid being deteriorated, or the bottle bursting
through an increase of temperature.
Condensed Milk. — The process was invented by De Leinac in 1852,
and modified later by Borden of New York, who introduced vacuum
pans for concentrating the milk without burning. In 1866 the Anglo-
Swiss Company started Borden's process on a large scale. The milk
is brought in every morning by farmers, who are kept under very
careful supervision as to cleanliness of surroundings, and absence of
disease. It is tested, mixed, and heated in a bath, pure white sugar
is added, generally beetroot, then run into the vacuum pans (closed
copper vessels from which the air and steam are exhausted), and
evaporated rapidly at a low heat for two or three hours, till it is of
the consistence of honey.
It has been kept in this way for upwards of twenty years. Great
cleanliness is of course necessary in the process. The tins must be
sterilised by scrubbing, then a jet of steam, and finally pure cold water.
If there be any imperfection in the process, or if the tin be not properly
sealed, the milk becomes solid and cheesy. If too highly concentrated,
the milk-sugar crystallises, and the preparation becomes gritty.
Condensed milk is perfectly wholesome, but the balance of its food-
value is disturbed by the enormous proportion of sugar, about 50 per
cent. For this reason it is unsuitable for infants. The directions on
* See the article on Bor\c acid, p. 99. t Patent No. 1,910, 1890.
18
274 DISINFECTION AND DISINFECTANTS.
the tin as to dilutions are frequently misleading — 1 in 5 or 6 for
adults, and 1 in 12 for infants^ras the concentration is only 1 to 3
or3i.
A condensed milk containing no added sugar and sterilised in tins
has recently been introduced. By diluting with twice its volume of
boiled water a fluid of the composition of ordinary milk is obtained.
Butter. — The production of sterilised butter has not been entirely
successful, owing to the fact that the proper sterilisation of the cream
is prevented by the necessary changing of the receptacles during the
manufacture. The cream is in consequence brought in contact with
numerous surfaces, and is necessarily subjected for a considerable
time to the action of the air. E. E. Ritsert* points out that notwith-
standing the occurrence of most diverse micro-organisms in rancid fats,
both aerobic and anaerobic germs die when added to the fresh unde-
composed fat, from which it is inferred that the change is not initiated
by them. He also found that xinder the influence of sunlight, which
killed the germs, the rancidity was produced more rapidly. Experi-
ments were therefore made with sterilised lard — (1) protected from
access of air, but exposed to sunlight, to diff'used daylight, and kept in
the dark; (2) with access of air, exposed to the sunlight, and kept in
the dark; (3) in atmospheres of moist and dry oxygen, carbonic acid,
nitrogen, and hydrogen. As a general result it may be stated that
the result favourable to the production of rancidity proved to be the
action of light during contact with air, the change being induced the
more rapidly the more intense the light. Thus it was found that
sterilised lard, either moist or dry, when kept from contact with air
in sealed tubes, remained free from rancidity for two months, even
though exposed to sunlight and warmth. Oxygen, both dry and
moist, was absorbed freely in the light, the fat becoming strongly
rancid in one month ; but none was absorbed in the dark, the fat
remaining quite fresh. Nitrogen and hydrogen were not absorbed in
any case, and the fat remained unchanged. Carbonic acid was absorbed
in the light, and to a less extent in the dark, but the lard only acquired
a tallow-like taste, and no odour.
G. Mullerf has invented an apparatus by which the whole process
of butter-making is conducted in the same vessel with the most com-
plete precautions. The cream is first sterilised by high-pressure steam
at about 103° 0. Any air which may enter on cooling is sterilised by
a cotton-wool filter. The churning is then proceeded with in the same
vessel, the butter-milk being run out at the bottom, sterilised air
entering at the top. Sterilised water is then added to wash the butter,
salt and colouring matter (sterilised) is added if desired, and finally
* Pharm. ZeUung, Sept. 13, 1890, p. 579. t Patent No. 8,264, 1892.
PRESERVATION OF FOOD. 27o
the butter is churned dry to remove excess of water. The product
is free from microbes, and will keep for a considerable time.
Butter that has once been churned cannot be melted without losing
its character as butter. If sterilised butter from Muller's process
above could be delivered by a screw pug mill into sterilised tins, so as
to fill them as nearly as possible, and then soldered up, avoiding
exposure, the ideal conditions would be fulfilled, and the butter ought
to keep for an almost unlimited time. It would be free from germs,
and would be secured from access of either light or oxygen.
Lactacidine, p. 202, is recommended for butter preservation, to be
removed by washing before use. Since butter entangles about 10 per
cent, of water, containing part of the butter-milk which in practice
cannot be thoroughly removed, and can only be partially preserved by
salt, no external application — neither this, nor boric, nor even salicylic
acid — can be depended on.
Cheese, as is well known, soon undergoes putrefactive changes,
without apparently rendering it unwholesome. Antiseptic, or, better,
aseptic, wrappers of close canvas, soaked in boric acid and boroglyceride
(p. 101) are here of value, and unobjectionable, as the rind is not eaten.
They may prevent the access of the organism producing ''tyrotoxicon"
(p. 266), which is the cause of poisonous cheese.
Wheat and other kinds of grain are subject to the attacks of numerous
fungi, such as ergot, mildew, etc, which render the flour prepared from
them unwholesome. The common remedy is to pickle with sulphate
of copper before sowing. Although the quantity of copper which
passes into the food is infinitesimal, it would be better if a less poison-
ous disinfectant could be found. Chloride and acetate of aluminium
have been well spoken of; they must be used very dilute, say 1 in 500,
or germination is checked.
Bread acquires from the air germs of all kinds, and under certain
conditions becomes poisonous. Hence the use of a covered bread-pan,
kept scrupulously clean and free from stale crusts, «fec., should be in-
sisted on. In the early part of 1894 Dr. Waldo drew attention to the
unsanitary state of London bakehouses. Filth, communication with
drains, privies in direct proximity, and personal contamination from
the work-people were discovered in a number of cases. Places where
the food of the people is prepared should be above ground, in strong
daylight (the fatal eflfects of light on bacteria have been before men-
tioned), well-ventilated, and clean. Much more supervision should be
exercised. It is almost useless to combat bacteria when they are
allowed to multiply in the daily food. The London County Council
has issued regulations on the subject, and legislation from Parliament
is awaited. Dr. Waldo and Mr. Welsh have also shown that organisms
276 DISINFECTION AND DISINFECTANTS.
and their spores are not destroyed by the ordinary proQess of baking.
By plate cultivation they succeeded in obtaining thirteen different
species of micro-organisms from the centre of recently baked loaves
from bakeries in different parts of London. The results show the
necessity of having proper regulations for bakehouses, as sewage
pollution of such places would mean that bread might be sent out to
customers charged with specific organisms. Microbes withstand a long
exposure to a much higher temperature than that to which the centre
of the loaf is exposed, without being destroyed, and there is no reason
to believe that even the greater number of the bacteria in the loaf are
killed. They also found that tinned and small loaves were often sterile,
and conclude that the number of bacteria in loaves seemed to bear a
direct relation to the dirtiness of the bakehouses. It is also important
that the flour, which undergoes in unsuitable warehouses a rapid
change, should be kept dry and sterile. Dr. Brown has suggested that
the use of flour has been the cause of many cases of outbreaks of
diseases, especially sporadic outbreaks of intestinal complaints. In
Bristol the number of such cases in the district has directly diminished
pari passu with the recent activity of sanitary interference with the
dirty bakehouses of the town.
CHAPTER XIV.
LEGAL STATUTES AND REGULATIONS.
Duties of a Medical Officer of Health, and of Sanitary Inspectors. Public Health
Act, 1875 : Clauses relating to Infection — Hospitals for Infectious Diseases —
Prevention of Epidemics — Mortuaries — Port Sanitary Authorities. General
Order of Local Government Board on Cholera, 1883: Regulations as to
Detention. Dairies, Cowsheds, and Milk Shops Order of 1885: Regu-
lation of Bakehouses — Housing of the Working Classes Act, 1890 — Public
Health (Water) Act, 1878 — Vaccination Acts — Burial Regulations — Merchant
Shipping Acts— Canal Boats Acts — Infectious Diseases (Notification) Act, 1889
— Infectious Disease (Prevention) Act, 1890. Public Health Amendment
Act, 1890. Public Health (London) Act, 1891: Rules for Hospitals for
Infectious Diseases, Local Government Board. Circular of the Medical
Officer of Health: Local Government Board Remarks on the Clauses.
Suggestions of the Society of Medical OfBcers of Health. Model Bye-
Laws of the Local Government Board : As to Cleaning, &c. — As to Nuisances
of Animals — As to Buildings. Metropolitan Asylums Board. Systems in
Other Countries : Brussels : Waggon Sluices — Rules as to Meat. Paris.
Germany. Berlin. Leipzig : The Suvern Mixture. Vienna. Complete
Regulations in Denmark. Report of American Public Health Association.
Quarantine: English System. Italy.
An outline may be here given of the Sanitary Regulations that
apply to our subject.
LEGAL STATUTES AND REGULATIONS. 277
Duties of a Medical OflBcer of Health (revised order of Local
Government Board, 1891) — Rule 6. — On receiving information of the
outbreak of any contagious, infectious, or epidemic disease of a dan-
gerous character within the district, he shall visit without delay the
spot where the outbreak occurred, and inquire into the causes and
circumstances of such outbreak, and in case he is not satisfied that all
due precautions are being taken, he shall advise the persons competent
to act as to the measures which may appear to him to be required to
prevent the extension of the disease, and take such measure for the
prevention of disease as he is legally authorised to take under any
statute in force in the district, or by any resolution of the sanitary
authority.
7. Subject to the instructions of the sanitary authority, he shall
direct or superintend the work of the inspector of nuisances, in the
way, and to the extent, that the sanitary authorities shall approve.
15. He shall give immediate information to us of any outbreak of
dangerous epidemic disease within the district, and shall transmit to
us a copy of each annual report and of any special report.
Sanitary Inspectors — Rule 9. — He shall give immediate notice to
the Medical Ofiicer of Health of the occurrence within the district of
any contagious, infectious, or epidemic disease.
10. He shall, subject to the directions of the sanitary authority,
attend to the instructions of the Medical Officer of Health with respect
to any measure which can be lawfully taken by an Inspector of
Nuisances under the Public Health Act, 1875, or under any statute
or statutes for preventing the spread of any contagious, infectious, or
epidemic disease of a dangerous character.
Public Health Act, 1875. — Earth-closets may be substituted for
water-closets if the local authority approves, and the local authority
may themselves undertake or contract with any person to supply dry
earth or other deodorising substance to houses within their district
for use in earth-closets (section 37).
The keeper of a common lodging-house, in the first week of the
months of April and October in each year, is required to limewash its
walls and ceilings (section 82), and to give immediate notice to the
Medical Officer of Health of any case of fever or infectious disease
occurring in the house (section 84), and to give any officer of the
local authority free access to every part of the house at all times
when required (section 85).
Similar regulations may be applied to houses let in lodgings.
The following are the provisions against infection : —
Where the Medical Officer of Health or any other legally qualified
medical practitioner certifies that the cleansing and disinfection of any
278 DISINFECTION AND DISINFECTANTS.
house or part thereof, or of any articles therein, would tend to prevent
or check infectious disease, it is the duty of the local authority to
give notice to the owner or occupier of the house in question requiring
him to do the necessary work within a specified time. The person on
whom the notice is served is liable on default to a penalty of Is. to
10s. for every day during which he continues to make default, and
the Local Authority is required to execute the necessary work, and
recover the expenses incurred from the responsible party.
If from poverty or other reason the person responsible is unable to
carry out the requirements of the local authority, the latter may,
with his consent, carry out the necessary work at their own expense
(section 120).
Any local authority may direct the destruction of any bedding,
clothing, &c., which have been exposed to infection from any danger-
ous infectious disease, and may give compensation for the same
(section 121).
The local authority may provide a proper place with all necessary
apparatus and attendance for the disinfection of bedding, &,c., and
may there disinfect any articles free of charge (section 122).
They may also provide and maintain a carriage suitable for the
conveyance of infectious patients, and pay the cost of conveyance of
such patients to a hospital or elsewhere (section 123).
Any person suffering from a dangerous infectious disorder who is
without proper lodging or accommodation, or lodged in a room
occupied by more than one family, or is on board any ship or vessel,
or who is lodged in any common lodging-house, may, on the certificate
of a legally qualified medical practitioner, be removed by order of any
justice to any suitable hospital or place provided within a certain
convenient distance. Any person wilfully disobeying or obstructing
the execution of this order is liable to a penalty not exceeding £10
(section 124).
Regulations may also be made by any local authority for removing
to a hospital persons brought within their district by any ship or
boat, who are infected by a dangerous infectious disorder (section 125).
Any person who —
1. While sufiering from any dangerous infectious disorder, wilfully
exposes himself without proper precautions in any street, public place,
shop, inn, or public conveyance, or enters any public conveyance
without previously notifying it to the owner, conductor, or driver,
that he is so sufiering ; or,
2. Being in charge of any person so sufiering, so exposes such
sufierer ; or,
3. Gives, lends, sells, transmits, or exposes, without previous dis-
LEGAL STATUTES AND REGULATIONS. 279
infection, any bedding, clothing, rags, or other thiiigs which have
been exposed to infection —
Is liable to a penalty not exceeding £5, and must also pay the
amount of any loss or expense incurred in disinfecting the public con-
veyance which lias been entered.
Every owner or driver of a public conveyance must immediately
provide for its disinfection after it has been used, to his knowledge,
by an infectious person, or is liable to a penalty not exceeding £o
(section 127).
Any person knowingly letting for hire any house or part thereof,
in which has been any person suffering from infectious disease, without
proper disinfection to the satisfaction of a qualified medical practi-
tioner, is liable to a penalty not exceeding £20 (section 128).
Any person who, when letting a house or part thereof for hire,
knowingly makes a false answer as to the occurrence of a case of
infectious disease within six weeks previously, is liable to a jienalty
not exceeding £20, or to imprisonment not exceeding one month
(section 129).
The Local Government Board may make or modify regulations for
the treatment of persons affected with cholera or any other epidemic
disease, and for the prevention of their spread, whether on water or
land, and may prescribe by what authorities it may be enforced.
Publication of such regulations in the London Gazette shall be regarded
as conclusive evidence of such regulations (section 130).
Hospitals for Infectious Diseases. — Any local authority may build
hospitals or temporary places for the reception of the sick belonging
to their district, or may contract with any person for the reception of
the sick. Two or more authorities may combine in providing a
common hospital (section 131).
The expenses incurred in maintaining a patient, who is not a
pauper, in such a hospital, may be recovered from the patient at any
time within six months of his discharge (section 132).
Any local authority may, with the sanction of the Local Govern-
ment Board, provide, or contract with any person to provide a
temporary supply of medicine, of course including disinfectants or
antiseptics, and medical assistance for the poorer inhabitants of their
district (section 133).
Prevention of Epidemic Diseases. — Whenever any part of England
appears to be threatened, or is affected by any formidable infectious
disease, the Local Government Board may make and modify regula-
tions for —
1. The speedy interment of the dead.
2. House-to-house visitation.
280 DISINFECTION AND DISINFECTANTS.
3. The provision of medical aid and accommodation, the promotion
of cleansing, ventilating, and disinfection, and guarding against the
spread of disease —
And may declare these regulations to be in force in any district,
and to apply to any waters within English jurisdictions (section 134).
The local authority within whose district the above regulations are
in force shall see to their execution, and appoint the necessary officers
for this purpose (section 136).
The local authority and their officers shall have power of entry on
all premises or vessels for the purpose of executing such regulations
(section 137).
The Local Government Board may, if they think fit, require two or
more local authorities, to act together for the purposes of these provi-
sions relating to the prevention of epidemic diseases (section 139).
A penalty not exceeding £5 is incurred by any person who wilfully
violates any of the regulations issued by the Local Government
Board, or wilfully obstructs the carrying out of these regulations
(section 140).
Mortuaries. — Where the body of any one who has died of any
infectious disease is retained in a room in which persons live or sleep,
or where any dead body is in such a state as to endanger the inmates
of the house or room in which it is retained, any justice may, on the
strength of a certificate signed by a legally qualified medical practi-
tioner, order the body to be removed, at the cost of the local authority,
to any mortuary provided by them, and order its burial within a
specified time. If the friends or relations of the deceased do not
undertake the burial of the body within the time specified, it is the
duty of the relieving officer to bury the body, but the expense may be
recovered from the person legally liable to pay the expense of the
burial (section 142).
Port Sanitary Autlwrities. — The Local Government Board appoints
the Sanitary Authorities of Ports from the neighbouring local
authorities (section 287). The port sanitary authority may delegate
its powers to any riparian authority within or bordering on their
district. The Lord Mayor and Common Council of the City of London
form the port sanitary authority of the Port of London (section 291).
The General Order of Local Govemment Board for Preventing the
Spread of Cholera, July 12, 1883, contains the following regulations : —
1. Every ship is deemed infected with cholera in which there is, or
has been during the voyage, or during the stay of the ship in a port
in the course of the voyage, any case of cholera.
Regulations as to Detention. — 2. If any officer of customs, on the
arrival of a ship, ascertain, or has reason to suspect, that the ship is
LEGAL STATUTES AND REGULATIONS. 281
infected with cholera, he shall detain the ship and order it to be
moored or anchored in such a position as he may direct.
3, No person must leave the ship while thus detained.
4, The oflBcer thus detaining any ship must give immediate notice to
the sanitary officer of the place where the ship is detained.
5, Such detention shall cease as soon as the ship has been duly
visited and examined by the Medical Officer of Health, or if the ship
is found to be infected with cholera, as soon as it has been moored and
anchored in pursuance of Article 10 of this order. The examination
must be commenced within twelve hours of the giving of the notice as
aforesaid, otherwise the ship shall be released from detention.
10. The master of any ship so certified to be infected with cholera,
shall moor his vessel at the place fixed for that purpose under Article 6,
and she shall remain there until the requirements of this order have
been duly fulfilled.
17. All articles soiled with cholera discharges must be destroyed,
and all clothing and bedding shall be destroyed or disinfected.
18. The ship must be disinfected and every article therein, according
to the directions of the Medical Officer of Health.
Dairies, Cowsheds, and Milk Shops Order of 1885. — All dairies and
cowsheds, whether new or not, can only be occupied as long as the
lighting, ventilation, including air space, and the cleansing, drainage,
and water supply are such as are necessary or proper —
(a) For the health and good condition of the cattle therein ; and
(b) For the cleanliness of all milk vessels used therein ; and
(c) For the protection of the milk against infection or contamination.
It is unlawful for any person following the trade of a cowkeeper or
dairyman, or purveyor of milk, or being the occupier of a milk store
or milk shop —
(a) To allow any person suffering from a dangerous or infectious
disorder, or having recently been in contact with such a person, to
milk cows or handle milk vessels, or in any other way to help in con-
nection with the preparation or sale of milk ; or (6) still less himself to
offend in a similar way.
No water-closet, privy, urinal, &c., is allowed to communicate with
any dairy or milk store, and the milk store must not be used as a
sleeping apartment, nor for any other purpose incompatible with the
cleanliness of the milk. Pigs are not allowed to be kept in a cowshed.
Local authorities may make regulations for prescribing precautions to
be taken against infection or contamination. The milk of a diseased
cow shall (a) not be mixed with other milk, nor (b) sold or used for
human food, and shall not (c) be used for the food of swine or other
animals until it has been boiled.
282 DISINFECTION AND DISINFECTANTS.
Regulation of Bakehouses (Factory and Workshops Acts of 1878
and 1883). — Where a bakehouse is situated in a town containing over
5,000 persons at the last census, all the inside walls and ceilings of its
rooms, and all the passages and staircases shall be painted with oil and
varnished with three coats, to be renewed once at least in every seven
years, and washed with hot water and soap once at least in every six
months (section 38, Act of 1878).
1. No water-closet, privy, or ashpit shall communicate directly with
the bakehouse.
2. Any cistern for supplying water to the bakehouse shall be sepa-
rate and distinct from the cistern supplying water to the water-closet.
3. No drain or pipe for carrying off sewage matter shall have an
opening within the bakehouse (section 15, Act of 1883).
The occupier of any bakehouse whatever is liable to a penalty if the
inspector of a local authority satisfies the court of summary jurisdiction
that the bakehouse is, on sanitary grounds, unfit for a bakehouse
(section 16, Act of 1883).
The medical officer of health, for the purposes of these sections,
has all the powers of an inspector under the Factory and Workshop
Act, 1878.
The Housing of the Working Classes Act, 1890, contains a number
of regulations as to unhealthy areas. The medical officer of health is
required, on complaint from ratepayers, to report on the condition of
any area complained of as being unhealthy (section 5). Part II. relates
to closing orders, demolition, re-housing, and re-building.
Public Health (Water) Act, 1878.— It is the duty of every rural
sanitaiy authority, from time to time, to ascertain the condition of the
water supply within their district, and to take all the necessary steps
for this purpose (section 7).
The Vaccination Acts, 1867, 1871, 1874, prescribe measures to be
taken for the vaccination or re-vaccination of unprotected persons.
Burial Regulations. — Burials within any place of worship built since
1848 are not allowed. No new burial ground can be opened within
a,ny city or town, and burials within any existing one may be prohibited
by order of the Queen in Council.
Merchant Shipping Acts, 1854 to 1876; Passengers Act, 1855. —
These contain orders as to the disposition of berths and air space
allowed per person carried.
The ventilation must be sufficient, no nuisances allowed, the drinking
water of good quality and sufficient in amount. On long voyages each
person must drink a daily allowance of lime juice, against scurvy.
Every passenger vessel on a voyage of eighty days for a sailing vessel,
or forty-five days for a steamer, when the number of passengers exceeds
LEGAL STATUTES AND REGULATIONS. 288
fifty, or of one day when the passengers exceed three hundred, must
carry a medical man. In the absence of a doctor, instructions are
given for the captain's guidance in cases of sickness. Captains are
required to destroy the clothing and bedding of cholera patients before
the ship enters an English port. Every passenger vessel must have at
least two properly arranged water-closets, and sufficient space allotted
for a hospital.
Canal Boats Acts, 1877 and 1884. — Rules as to air space, cleanliness,
and infectious diseases.
The Infectious Diseases (Notification) Act, 1889. — Both the house-
holder and the medical practitioner are responsible for the notification
of each case of infectious disease to the medical officer of health for the
district. This applies to any building, ship, boat (English or foreign),
any tent, van, shed, or similar structure, whether belonging to Her
Majesty or not. Penalty, forty shillings. The infectious diseases
specified are : — Smallpox, cholera, diphtheria, membranous croup,
erysipelas, scarlatina, scarlet fever, typhus, typhoid, enteric, relapsing,
continued, or puerperal fever, and also any infectious disease to which
the Act has been applied by the local authority.
The Infectious Diseases (Prevention) Act, 1890. — Increased control
over milk supply is given in section 4, which enacts that if the medical
officer of health is in possession of evidence that any person in the
district is sufiering from infectious disease attributable to milk supplied
to a dairy within or without the district, or that the consumption of
milk from such dairy is likely to cause infectious disease to any person
residing in the district, such officer shall, after receiving the authority
of a Justice for this purpose, have power to inspect the dairy in question,
and, if accompanied by a veterinary surgeon, to inspect the animals in
it. If on such inspection the medical officer of health is of opinion
that infectious disease is caused from consumption of the milk supplied
therefrom, he shall report thereon to the local authority, who shall
give notice to the dairyman to appear before them, and to show cause
why an order should not be made requiring him to discontinue supply-
ing the milk. If in the opinion of the local authority he fails to show
such cause, the order may be made, and shall hold good until they are
satisfied that the cause of infection has been removed.
Sees. 5 and 6 give increased powers of disinfection to the officers
of the local authority. It is generally admitted that domestic disin-
fection is of a most unsatisfactory character ; by section 6, power is
given to remove bedding, &c., for the purpose of disinfection by the
local authority at the cost of the latter.
It is forbidden to retain the body of any person who has died of an
infectious disease elsewhere than in a public mortuary, or in a room
284 DISINFECTION AND DISINFECTANTS.
not used as a dwelling place, sleeping-place, or work-room, longer than
forty-eight hours (sec. 8).
By order of a Justice of the Peace, any person suffering from
infectious disease, and then in a hospital for infectious disease, may,
although unwilling, be detained there until free from infection, if it
can be shown that he is without proper means of isolation and lodging
elsewhere (sec. 12).
The throwing of infectious rubbish into ashpits, &c., is forbidden
(sec. 13).
The local authority is required to provide free temporary shelter
with the necessary attendance to the members of any family who have
been compelled to leave their houses to enable them to be disinfected
by the local authority (sec. 15).
The bodies of persons dying of infectious diseases in . hospitals are
only allowed to be removed for the purpose of being forthwith buried
(sec. 9).
The Public Health Amendment Act, 1890, does not apply to the
metropolis. It forbids the discharge of injurious matter into the
sewers (sec. 16), gives power to regulate public conveniences, and
those in lodging houses, factories, or workshops. Rooms over privies,
middens, or ashpits, are not allowed to be used as dwelling or sleeping
rooms (sec. 24). It is not lawful to erect a new building on any
ground filled up with offensive matter, unless the latter is removed by
excavation, or has become innocuous.
Urban authorities may make bye-laws for prescribing the times for
removal through the streets of offensive or noxious matters, and for
providing that the vessels or carts be properly constructed and covered
(sec. 26). The section of the Public Health Act relating to un-
sound meat is made to apply to articles which have been already
sold (sec. 528).
The Public Health (London) Act, 1891, consolidates and amends all
previous sanitary enactments. Section 15 says — Any person damaging
or destroying any drain, water-closet, or Avater-supply apparatus, is
liable to a fine of £5 (sec. 15).
It is compulsory on the sanitary authorities and County Council to
make bye-laws for the cleansing of streets and prevention of nuisances
from rubbish, offal, &c., and as to paving of open spaces about houses ;
and on the County Council to make bye-laws for the removal of filth,
&c., in properly covered vessels, and as to the filling up of cess-
pools, &c.
The petty sessional court may prohibit the using of any place for
the keeping of any animal, if it is proved to the satisfaction of the
court that the place is unfit for this purpose (sec. 18). (This
LEGAL STATUTES AKO REGULATIONS. 285.
section applies to fowl-houses, pigeon-houses, rabbit-hutches, <kc., and
the keeping of cats and dogs.)
By section 22 the removal of house refuse and street refuse is placed
under the same category as offensive trades under private control, and
the sanitary authority are liable to be proceeded against for any in-
fringement of the bye-laws made by the County Council in this behalf.
The regulation of dairies and cowsheds is placed under the control of
the County Council (sees. 23 to 28). It is made the duty of the
sanitary authority not only to keep the streets swept and cleaned, but
also to secure the regular periodic removal of house refuse. If after
forty-eight hours written notice, when the house refuse has not been
removed from any premises at the proper period, the sanitary authority
fail without reasonable cause to comply with this notice, they are liable
to a fine not exceeding £20 (sees. 29, 30).
Sec. 48 constitutes a dwelling-house without a proper supply of
water unfit for habitation; and by section 49 makes any Water
Company liable to a fine of .£10 if within twenty-four hours after
cutting off the water supply to any house for non-payment of water-
rates they do not give notice to the sanitary authority. Every sanitary
authority is required to make bye-laws for the cleansing of receptacles
for storage of water for drinking or domestic purposes.
Sees. 55 to 57, on the notification of infectious diseases, make it
compulsory on Medical Officers of Health to send a copy of the
certificate to any school attended by any child who is an inmate of
the infected house.
Sees. 58 to 81 make compulsory the provision of disinfecting apparatus
and carriages for carrying infected materials, free of charge, by the
Sanitary Authority.
Every Sanitary Authority is required to provide and fit up a public
mortuary (sec. 88).
Memorandum on Hospital Accommodation— Local Government Board.
— When two contagious diseases break out at the same time, they
should each be separately isolated. In towns, and for several villages
of smaller size, there should be provided at least two special wards
with four beds in each, in order that the sick may be isolated from
the commencement. Proposed plans and ■ sections accompany the
Memorandum.
In rural districts without a hospital, a trustworthy married couple
without children may be charged with the isolation and care of cases
of infectious disease. In the event of a more serious epidemic several
lodgings may be hired, or the sick may be isolated in temporarily
erected tents or barracks. Fever hospitals in urban districts ought to
have one bed for every 1,000 inhabitants. In a manufacturing town
286 DISINFECTION AND DISINFECTANTS.
with a very dense population, the proportion oxight to be even greater.
Permanent fever hospitals are built on the system of separate pavilions.
Illustrations and details are given in the Memorandum, which cites
as examples St. Thomas's Hospital, the Herbert Hospital, and the
Royal Infirmary at Edinburgh. The laundries and mortuaries should
be in separate buildings.
In wards for infectious diseases there should be openings for
admission of fresh air between each bed, a little above the floor, so
that pure air bathes the patient's bed. They should be furnished
with a grooved fastening, so that the admission of air can be gradu-
ated. The openings for the extraction of foul air should be near
the ceiling, and as remote as possible from those admitting fresh air.
They should, unless entering into the chimney breast, be cai'ried
vertically to the roof, and be pi-ovided with an aspirating cowl.
2,500 cubic feet of fresh air should be supplied for each patient per
hour. The openings should be easily cleansed and freed from dust,
and protected by an outside grating. Every hospital should possess
a disinfecting apparatus.
Memorandum on Ambulances.— In the construction, special regard
should be had to the fact that after each \ise, it has to be cleaned and
disinfected to the satisfaction of a Medical Officer.
Bules for Hospitals for Infectious Diseases (Local Government
Board). — Among these are : —
(3) No person is admitted without the permission of the Medical
Officer.
(4) No patient is permitted to leave until discharged by him.
(5) The patient's clothes must be disinfected before being given up
to him at his discharge.
(6) Officers and servants are not allowed to leave without authority
of the Medical Officer, and they must first change their clothes.
Circular of the Medical Officer (Local Government Board). — After
insisting on the proper ordering of houses, drains, &c., the circular
contains : —
"Sec. 4. In the removal of filth during epidemic disease, it is
commonly necessary to employ chemical agents for reducing and
removing the ofience or harm which may be involved in the disturb-
ance of the filth. In the removal of privy contents these agents are
more particularly wanted if the disease be cholera or enteric fever.
The chemical agent should be used liberally over all exposed surfaces
from which filth has been removed. Unpaved earth close to dwellings,
if it be sodden with slops or filth, ought to be treated in the same
way."
" Sec. 5. Sources of water supply should be well examined. Water
LEGAL STATUTES AND REGULATION'S. 287
from sources which can in any way be tainted by animal or vegetable
refuse, especially those in which there may be any leakage or filtration
from sewers, drains, cesspools, or foul ditches, ought no longer to be
drunk, above all where the disease is cholera, diarrhoea, or enteric
fever. If unfortunately such is the only water to be got for the time,
it must be boiled, and then not drunk later than twenty-four hours after
boiling. Filtering of the ordinary kind cannot by itself be trusted to
purify the water (see p. 15). It cannot be too distinctly understood
that dangerous qualities of water are not obviated by the addition of
wine or spirits."
Sec. 6 (after remarks about dairies). ..." Even apart from
any apprehension of milk being concerned in a particular outbreak of
disease, it is desirable that English people should adopt the custom,
which is always followed in some Continental countries, of boiling all
milk at once upon its reception into a house."
Sees. 7 and 8 deal with washing, lime-whiting, overcrowding, and
ventilation.
Sec. 9 enjoins cleanliness, rapid removal or destruction of refuse,,
and avoidance of delay in disinfecting.
Sec. 10 gives directions as to discharges from the sick (see p. 233).
" In enteric fever and cholera the evacuations should be looked upon
as capable of communicating an infectious quantity to any night-soil
with which they are mixed in privies, drains, or cesspools, and after
such disinfection of them as is practicable they should be disposed of
without delay and under the safest conditions the local circumstances
permit." (It is quite impossible for this to be done by private effort ;
the evacuations can only be securely sterilised by heat, and this would
involve either a s'team apparatus or a dust-destructor. The local
authorities must arrange to remove the evacuations daily in sealed
iron receptacles, which must be heated for several hours in steam
ovens, or steam passed through them, the gases being led into a fire
and burnt. A small quantity, about 1 in 500, of phenol, or a cresol
preparation (see p. 170) should be added ; it has been proved that dis-
infectants, when hot, act with much more energy than when cold ; or
mercuric chloride may be used. The residue is then safe.)
"Sec. 17. Provision by the public authority for disinfection by
heat of bulky articles, and of those which cannot without injury be
exposed to chemical agencies, ought always to be in readiness." (Such
provision could be associated with the arrangements for the sterilisation
of excreta described above. Many of the existing apparatus are not
large enough.) "Without such provision no complete disinfection can
be eflfected. Partial and nominal disinfection, besides being wastefui,
may be mischievous, as giving rise to false security."
288 DISINFECTION AND DISINFECTANTS,
Sec. 18. This rule commends a system of domestic disinfection to
sanitary authorities "who have already provided adequate public means
for the disinfection and for the disposal of infected matters and things."
Soiled linen is treated with mercuric chloride solution.
"In places provided with proper systems of excrement disposal,
excrements of cholera and enteric fever, after having been treated in
detail with the same disinfecting solution (acidified mercuric chloride
in ample quantity), may be safely put into the ordinary closet ; but
special care as to the flushing of drains and sewers, and special frequency
in the removal and exchange of excrement receptacles, must be insisted
upon. Where the closet is one that communicates with the cesspool
or privy pit, the best arrangement for the disposal of infected stools
that under these improper local circumstances may be found practicable
will have to be adopted." This rule ought to be reconsidered. Koch
has proved that mercuric chloride may easily be insufficient even in
larger amount than is here recommended (p. 137). The throwing of
cholera excreta, even " disinfected " as here described, into closets, to
pass thence into rivers and streams, might spread the disease through
an entire neighbourhood. Nothing short of the sterilisation by heat,
as detailed above, is at all certain.
"A substance generally available in the removal of filth from privies
and ashpits, and for application to foul earth and the like, is sulphate
of iron (green copperas), either in a strong solution made by stirring
crystals of the salt with five or ten times their bulk of hot water, or in
the form of powder, to which form the crystals may easily be brought
by desiccation. This agent should be used in quantity sufficient to
destroy all odour, and in the removal of filth accumulations it should
be well mixed with successive layers of the matter to be removed.
The dry form of application is to be preferred where masses of wet or
solid filth have to be dealt with." (But Dr. Thome himself says : " It
cannot confidently be stated that either the iron salt or any available
substance will effect a true disinfection of such masses of filth as are
here in question. The removal of dangerous filth is here the object to
be attained." It is strongly to be hoped that a protest will be made
against the recommendation of a plan admittedly inefficient, since
removal without exposure," and the subsequent action of heat, are the
only courses eff'ectual. Even for temporary removal of stench, there
are better remedies than sulphate of iron; for instance, a cresol powder,
or liquids of the Sanitas type, or saprol, or other pyridine-containing
disinfectant.)
"For the disinfection of the air of rooms . . . sulphurous acid
, , . is ordered, and wall paper should be stripped." . . .
Suggestions of the Society of Medical Officers of Health. — Most of
I
LEGAL STATUTES AMD REGULATIONS. 289
these have been previously noticed. The following are the chief
points : —
" 1. Hang up a sheet outside the door of the sick room, and keep it
wet with a quarter of a pint of carbolic acid, No. 4, or a pound of
chloride of lime, with a gallon of water. The floor should be sprinkled
. . . and the cloths hung up."
" 2. Everything that passes from the sick person should be received
into ^ pint of green copperas, 1 lb. to the gallon. A like quantity to
be added before emptying."
" 3. Every sink, closet, or privy should have a quantity of one of
the above-named disinfectants poured into it daily, and the greatest
care should be taken to prevent the contamination of well or drinking
water by any discharges from the sick person."
" 4. All cups, glasses, spoons, &c., used by the sick person should he
first washed in the above-named solution of carbolic acid, and after-
wards in hot water, before being used by any other person," (It
would be better to insist that the utensils used by the sick person
should not be used by any one else. At the end of the illness,
they are better destroyed, but if they must be used, they should be
boiled for an hour or two with water and washing soda, and then
wiped dry. No carbolic acid is necessary.)
" 5. All the bed and body linen . . . before being taken from
the room, should be first put into a solution of carbolic acid . . ."
6. Prescribes linen garments for nurses, and washing the hands
with carbolic soap.
7. Visitors should not be allowed, as their clothing is apt to carry
away infection.
" 8. The scales and dusty powder which peel from the skin in scarlet
fever, and the crust in small-pox, being highly infectious, their escape
may be prevented by smearing the body of the sick person all over
every day with camphorated oil. This and the after use of warm
baths and carbolic soap are most essential. The sick person must not
be allowed to mix with the rest of the family until the peeling has
entirely ceased and the skin is perfectly smooth ; clothes used during
the time of illness, or in any way exposed to infection, must not be
worn again until they have been properly disinfected " (p. 283).
9. Directions for final disinfection of the room by burning sulphur,
and bedding, &c., by heat. The amount prescribed is not sufficient
(see p. 94).
10. Children from an infected house not to attend school until
they obtain a certificate from the medical attendant.
11. In case of death the body should not be removed from the
room except to a mortuary ; a pound or two of carbolic powder should
19
290 DISINFECTION AND DISINFECTANTS.
be put into the coflBn, which should be fastened down and buried
■without delay. (Cremation is here to be advocated).
Model Bye-Laws of Local Goverament Board as to Cleansing, &c
The following pertain to our subject (the wording is slightly con-
densed) : —
Sec. 1. The occupier of any premises abutting on a street shall clean
the adjoining pavements at least once a day, except on Sundays.
Sec. 2. He shall remove house refuse from his premises at least once
a week.
Sec. 3. He shall at least once in three months cleanse earth-closets
provided with a fixed receptacle and supply dry earth ;
Sec. 4. Those with a movable receptacle, at least once every week ;
Sees. 5 and 6. Privies of either kind, at least once a week ;
Sees. 7 and 8. Ashpits, whether mixed with faecal matter ornot; and
Sec. 9. Cesspools.
Model Bye-Laws as to Nuisances and Animals. — Sec. 3. Salt and
snow must be effectually removed.
Sec. 4. Ashes, &c., must not be deposited on paths or roads, must be
swept up, and must be removed in a covered receptacle, instead of in
open pails.
Sec. 4a. Privies, cesspools, <tc., must be emptied within special
hours (p. 240).
Sees. 5 to 8. Ashes, &c., must be removed in covered carts, to
special depdts, 100 yards distant from houses, every twenty-four hours.
Sec. 9. When filth is deposited for agricultural purposes, the distance
from the nearest inhabited premises must be at least 100 yards, and
the filth must be forthwith ploughed in or covered with mould
(ordinary earth does not sterilise it, see p. 238).
Sec. 10. Pigs must not be kept, nor swine dung deposited, within
100 yards of a house, nor so as to pollute a water supply.
Sec. 11. Cattle and their dung must not endanger any water used
for drinking, domestic, or dairy purposes.
Sec. 1 2. Regulations as to manure from stables, &c.
As to Buildings. — Sees. 55 to 59. Rooms and public buildings must
have proper ventilation according to specified details.
Sec. 60. Drains and water pipes must be disconnected from the
sewer by ventilated traps.
Sec. 62. Regulates the material, diameter, setting, jointing, and
course of drain pipes ; and
Sees. 63, 64, and 65. The traps, gratings and ventilating shafts
which should be carried to the top of the house.
Sec. 66. No inlets to drains are allowed within houses. The soil
pipe must be at least 4 inches in diameter and be fixed outside the
LEGAL STATUTES AND REGULATIONS (OTHER COUXTRIES). 291
building and continued upwards without bends or angles to a height
above the top windows. All waste and overflow pipes must be taken
through an external wall of the house, and discharge in the open air.
Sees. G8 and 69. Water-closets within houses shall have at least
one of their sides to an outer wall, must be ventilated, have a special
cistern and sufficient flush, must not have a "container," or "D-trap."
Sees. 70, 71, and 72 relate to earth-closets.
Sees. 73 to 79. Privies must be 6 feet from a house, 40 to 50 feet
from any source of drinking water (not sufficient — Neicalwlme), easily
accessible, ventilated, the floor non absorbent, raised above the ground
level, and sloping towards the door (to prevent stagnant water).
The receptacles must not be exposed to rainfall or drainage.
• Sees. 80 to 85. Ashpits must be 6 feet from a house, 30 to 40 feet
from any well, &c., roofed, cemented, and easily cleaned.
Sees. 86 to 89. Cesspools must be 50 feet from a house, 60 to
80 feet from any well, &c., easily emptied without passing through
the house, properly cemented, unconnected with a sewer, covered,
and adequately ventilated (cesspools should be forbidden where
there are sewers).
The model bye-laws as to lodging-houses resemble those of the
Public Health Act, 1875, with many additions and improvements.
Those as to slaughter-houses are in considerable detail.
Metropolitan Asylum's Board. — The disinfection of ambulance car-
riages and steamers is done by washing with carbolic acid.
The hospital linen is soaked in carbolic solution, and then boiled
and washed (it requires not less than 1 in 20 carbolic to disinfect
linen ; the solutions usually employed are not as strong as this — e.g.,
the one recommended by the Society of Medical Officers of Health
(p. 153) is only \ pint to a gallon, or 1 in 32. This means that
carbolic disinfection as commonly carried out is imperfect. In the
new hospitals clothing is disinfected by steam).
Legislation as to Vagrants.— On July 19, 1894, a conference of
Medical Officers of Health and others was held at the hall of the
London County Council to consider whether means could be adopted
to prevent the spread of infectious diseases by vagrants. The matter
is still under discussion.
SYSTEMS IN OTHER COUNTRIES.
In some respects the sanitary administration of Brussels is superior
to ours, and compulsory notification has been enforced since 1824.
Slaughtering is only allowed in the town abattoirs. The meat is
inspected and stamped, and the name and address of the owner, and
destination of the meat, are recorded, with the date and hour; this
292 DISINFECTION AND DISINFECTANTS.
arrangement has secured almost perfect protection against diseased
meat, and also that it should be fresh. Even " offal " must be dressed
at the abattoir and stamped. During transport the stamp and certifi-
cate must be shown when demanded. The control of other foods is
also much more satisfactory than ours.
The Waggon Sluices used to clean deposits from the sewers travel
along rails throughout their length. The deposits being continually
removed, cannot decompose and produce foetid gases, and the air of the
sewer is comparatively pure.
The corpses of persons having died of an infectious disease are
wrapped in linen clothes soaked in carbolic acid. The body is then at
once conveyed to the observation chamber of the mortuary outside the
town, and is interred as soon as certain signs of death have appeared.
Special clothes are worn by the undertaker's men, and these are re-
turned after use to the station for steam disinfection.
Germany has necessarily instituted compulsory inspection of pork
(see p. 271), and authorised inspectors are appointed for this purpose.
If infested with trichinosis, the fat only can be used, after being
cooked for three hours ; the rest of the meat is buried. Tuberculosis
is also keenly looked after.
The rules as to corpses and burials are very explicit (see p. 280).
Corpses must not be exposed in the churches. Midwives are forbidden
to wash or lay out corpses.
In Berlin only water-closets and movable tubs are allowed. Steam
disinfection is carried out at the Reichemberger Strasse station.
Mercuric chloride is not used as in Paris, but the walls of rooms are
rubbed with bread and then washed with 2| to 5 per cent, carbolic
acid. Various chemical methods of disinfection of excreta are used in
Leipzig. "The Suvern Mixture" is made by soaking 42*5 grammes of
quicklime with 102 of water, and adding thereto 8*5 kilos, of coal-tar
and 8 '5 of magnesium chloride in an equal quantity of water; it is
diluted with water when used. Half a kilo, is used for each person
per day. It is mixed with the excreta when removed ; the mixture
then flows into settling reservoirs, the liquids run off into the sewers,
and the solid deposit is cleared out about once a year. Palmberg
states that both the solid and liquid matters are rendered inoffensive.
The theory is that the carbonic acid developed by the fermentation of
the organic matters combines with the lime to cause a deposit of car-
bonate of lime which encrusts or petrifies the microbes ; the spores as
they develop are destroyed in the same way. The ammonia generated
by putrefaction is fixed by the magnesium chloride, the sulphuretted
hydrogen by the lime. " The deposit consists of carbonate of lime
mixed with organic matters ; it is greyish in colour, inodorous, and
LEGAL STATUTES AND REGULATIONS (OTHER COUNTRIES). 293
aseptic."* It is useless for manure. The process of Friedrich and
Glass is also much used. The composition of the disinfecting powder
is not given.
In Vienna, 5 per cent, carbolic acid (the least eflfective strength),
sulphurous acid fumigation, and steam are the legal disinfectants.
In Denmark very elaborate regulations are in force, and the follow-
ing summary may therefore be useful as a model for further legislation
in this country. The rules were proposed by the Royal Board of
Health for disinfection, and were carried out in pursuance with the
Act of April 20, 1888, on measures against the spread of infectious
diseases, and are now established in Denmark in virtue of the authority
vested in the Minister of Justice by the said Act. It rests with the
Boards of Health to supervise the proper carrying out of public disin-
fection ; the Boards must also see that the necessary staff and appli-
ances are at hand, and that the former are properly instructed in their
duties. It is the duty of the medical man sending in the requisition
for disinfection to state what rooms or things are to be disinfected.
Disinfectants. — (1) Boiling in water for at least twenty minutes.
(2) Steam under or without pressure in "disinfecting ovens"; those most
generally used are Reek's and Geneste & Herscher's (see pp. 45, 47).
(3) Carbolic acid in 5 per cent, solution, " strong carbolic water," or in
2 per cent, solution, "weak carbolic water," according to the purpose
for which it is used. (4) Chloride of lime is used partly as a powder
mixed with twice the quantity of clean dry sand, for covering excreta,
dung-heaps, and such like ; partly in strong solution, viz., 4 parts to
100 parts. To be thoroughly efficient, chloride of lime must meet the
requirements of the Danish Pharmacopoeia, and contain 20 per cent, of
available chlorine, and must be kept in the dark in corked glass recep-
tacles, which is also the case with the solutions. The solutions are
prepared best in the following manner : — The chloride of lime is made
with a little (clean) water to a smooth paste, after which the rest of
the water is gradually stirred in for thirty minutes. An insoluble
residue will remain, which may be removed by filtration, but this is
not necessary when the solution is only to be used for disinfecting the
patients' excreta, «kc. The solutions are most efficient when freshly
made. (5) Mercuric chloride (corrosive sublimate) in a solution of
1 part to 1,000 parts of boiled water should, on account of its poisonous
nature, be only used under the supervision of the sanitary authorities
or of medical men ; on this account also no vessels should be used in
the preparation of the solution from which either man or beast drink
or eat, nor such in which drink or food is kept. Further, the solution
of mercuric chloride must not be thrown away in places where such
* Pcdmberg, p. 409.
294 DISINFECTION AND DISINFECTANTS.
may give rise to poisoning ; should the solution be used in the disin-
fection of any utensil, it must, when the disinfection is finished, be
carefully removed from the object disinfected by repeated rinsing or
washing with clean water that has been boiled. A solution of soda
should be employed for the same purpose in rooms which have been
disinfected with mercuric chloride (see below). As mercuric chloride
is decomposed by metals, metallic vessels must not be used in the
preparation of the solution, neither must any articles made of metal
be disinfected with this agent.
To prevent mistakes the solution of mercuric chloride may l)e
coloured with any dye which does not injure the objects to be disin-
fected (especially woollens, or silks which easily take dyes), for instance
the aniline dye, which is at present manufactured in Germany and
known as Wasserblau, which can be obtained from C. A. Kahlbaum,
Berlin. A little acetic acid is recommended to be added to preserve
the colour. (6) Aeration may be employed to second any of the other,
agents, or when it is impossible to disinfect in any other way, in which
case it must be continued for three or four weeks. (7) All worthless
articles (straw, hay, or seaweed mattress stuffing, old clothes, cloths
which have been used for wiping away infectious discharges, &c.)
should be burnt as soon as possible, the necessary precautions being
taken to prevent the spread of the disease.
Special Rules for Disinfection.— 1. The o?isc/tar^es of patients (dejec-
tions, vomited mattei", sputa, urine) must be immediately mixed with
the strong solution of chloride of lime, or with strong carbolic water.
It is advisable to pour a little of these disinfectants into the vessel
before it receives the discharge. The total quantity of the agent
employed must be at least equal to that of the discharge. The mix-
ture should be immediately poured into a tight, well-covered vessel,
specially used for that purpose, and placed in an isolated place; in
this vessel the mixture is to remain until the disinfectant has acted —
viz., one hour when a solution of chloride of lime is iised ; four hours
when carbolic water is used. This vessel should be emptied daily,
preferably into a pit, dug especially for that purpose ; if this is not
possible, into a privy, the contents of the pit or privy to be imme-
diately covered with a layer of the mixture of chloride of lime and
sand, should circumstances necessitate the immediate emptying of the
mixture into the pit or privy.
It should be carefully stirred with a stick, and the stick left in it.
If the mixture is emptied into a tub, this must be changed daily.
2. Privies. — Excreta contained in privy pits or tubs should be
covered with a thick layer of a mixture of 1 part of chloride of lime and
2 parts of sand. Privy tubs should be frequently emptied, and after-
LEGAL STATUTES AND BEGULATIONS (OTHEB COUNTRIES). 295
•wards disinfected with a 4 per cent, solution of chloride of lime and
6 per cent, carbolic water ; the seat and floor of the privy should be
washed with one of these disinfectants at least twice daily. The pan
and pipe in water-closets, as also urinals, should be cleansed at least
twice daily with one of these disinfectants.
3. Clothing. — Dirty clothes, bed-clothes, pocket handkerchiefs,
towels, cloths, and such like, should not be shaken or brushed pre-
vious to disinfecting. In Denmark the rules in force are as follows : —
Everything which can be washed without injury should immediately
be put into boiling water for thirty minutes, or into 2 per cent,
carbolic water, or the solution of mercuric chloride, for at least four
hours ; after being wrung out, the articles should be placed in a vessel
full of water, in which they remain until they can be washed. If the
articles cannot be placed in the above-mentioned disinfectants in the
sick room itself, they must only be taken from it wrapped up in a
sheet or sack saturated with 2 per cent, carbolic water. Clothes
should not be sent to the wash from infected places, unless they have
been subjected to the treatment above mentioned, and should not be
washed until they have been boiled for thirty minutes in soap and
water. Hay and straw mattresses should be opened after being
moistened in such a way that their opening causes no dust ; the hay
or straw should be removed or burnt, the covers treated in the manner
above mentioned. Persons employed in washing the articles above
mentioned should, on the completion of their work, disinfect them-
selves according to the rules given below for the persons engaged in
disinfection. Everything which cannot stand boiling water or wash-
ing should be taken in the manner above described to the disinfecting
oven, to be disinfected with steam. If this is impossible, the articles
should be brushed with a brush dipped in strong carbolic water; after
which they should be aired for three or four weeks in a dry place pro-
tected from rain — places where there is a draught being preferred.
Spots of blood or matter must be removed by soaking in a cold disin-
fecting fluid, previous to disinfection, either with boiling water or
steam. Leather, morocco, or indiarubber articles (boots and shoes,
boxes, bags, <fec.), which would be injured by steam, should be carefully
washed over several times with 5 per cent, carbolic water.
4. Upholstered furniture, carpets, curtains, and such like, when
circumstances permit, should be disinfected with steam ; they should
not be beaten or brushed previous to disinfection, and should be taken
to the place for disinfection wrapped in sheets or sacks saturated with
2 per cent, carbolic water. When it is not possible to employ steam,
the articles must be brushed with a brush dipped in 5 per cent,
carbolic water (if they can stand it), after which they should be aired
296 DISINFECTION AND DISINFECTANTS.
for three or four weeks in a dry place, protected from rain; a
draughty place being preferred.^ Polished or carved furniture, pic-
tures, and articles which cannot stand strong carbolic water, should
be wiped with soft cloths dipped in 2 per cent, weak carbolic water
and wrung out; they should then be immediately dried with a clean,
dry cloth. Any parts of the above-mentioned articles which are not
polished or stained, should be washed twice with 5 per cent, carbolic
water ; they must be first washed with hot soap and water, should
they be very dirty. The cloths washed in the cleaning should be
washed or burnt immediately. All articles which can be placed in a
fluid without injury, should be boiled or put into a strong or weak
carbolic water for four hours, according to their nature. Articles of
no value should be burnt.
5. Rooms, Carriages, &c. — The sweeping or dusting of such is not
permissible. Whitewashed or oil-painted walls, floors, ceilings,
windows, doors, wainscotting, and other woodwork, should be dis-
infected with 5 per cent, carbolic water or solution of mercuric
chloride; the latter only under supervision (see above). "With
these disinfectants the surfaces should be wiped with cloths or,
(when they can stand it) should be scrubbed with a scrubbing brush,
or sprinkled by means of a syringe or spray apparatus constructed
for that purpose. Plaster walls may also be disinfected by giving
them a coating of a mixture of 1 part chloride of lime and 2 parts
water. Such surfaces as cannot stand washing or scrubbing, for
instance wall papers, covers, or fixed cushions, should be sprinkled
with the disinfectant fluids above mentioned (which do not injure
many wall papers) or carefully rubbed with pieces of soft bread,
the crumbs being swept up and burnt. Surfaces disinfected with
the solution of mercuric chloride should be washed over or sprinkled
with a solution of soda (1 part to 100 boiled water), at least thirty
minutes after disinfection. Care should be taken that all parts of
the surfaces to be disinfected are thoroughly exposed to the dis-
infectants, and that these latter penetrate into all cracks and holes,
which, if necessary, should be scraped free from all dirt and dust,
this being wiped away with cloths dipped in a disinfectant fluid,
the cloths to be afterwards burnt. Special care should be taken
in cleansing such parts of the floors or walls as have been soiled
by the patient's discharges ; wall paper thus soiled, after having
been moistened with one of the above-mentioned solutions should
be taken off or burnt. Disinfection being completed, the room,
carriage, &c., should be left for twelve hours ; after which time the
surfaces disinfected should be thoroughly washed with warm water
and soap. Finally, they should be exposed to a thorough draught.
LEGAL STATUTES AND REGULATIOKS (OTHER COUNTRIES). 297
if possible for at least a week. In ships, special care should be taken
as to the disinfection of the bilge. Ships in harbour are disinfected
according to special rules, under the supervision of the authorities
in question. In ships at sea, the bilge water should be pumped
out, and the bilge thereafter rinsed out with salt water at least
twice.
6. Persons] who have been in contact with patients suffering with
infectious diseases, should first wash their hands, arms, and face in
weak carbolic water or a weak solution of chloride of lime, then in
warm soap and water. Their clothes and hair should be brushed with
brushes dipped in weak carbolic water. Persons devoting themselves
to the nursing of patients, or constantly staying in the sick room,
should, when their task is completed, thoroughly disinfect themselves
before visiting healthy persons or dwellings. This disinfection should
consist of thorough washing of the whole body, and brushing of the
hair with weak carbolic water, or weak solution of chloride of lime ;
after which a warm bath should be taken, if possible ; finally, clothes
free from infection should be put on. Clothes worn while nursing
should be left in the infected place. Nurses should carefully wash
their hands, first with carbolic water, or the weak solution of chloride
of lime, and afterwards in warm soap and water, every time they
have reason to believe that infectious germs have stuck to them.
Nail brushes should be used for brushing the nails. Convalescents
should be washed all over the body (hair included) with weak
carbolic water, or the weak solution of chloride of lime, after which
they should take a warm bath, and put on a suit of clothes free from
infection, before they mix with healthy persons. The clothes worn
during illness should be disinfected according to the regulations laid
down above. Persons employed in disinfecting rooms, furniture, &c.,
should wear a linen suit consisting of a blouse, trousers, and cap with
a brim in front and behind, which suit should be disinfected after
having been used. The persons who have been engaged in disinfect-
ing should cleanse their hands, arms, and faces as above prescribed.
7. Drinking water, milk, beer, provisions, &c., which have been
exposed to infection, should be rendered harmless in the most eflfective
manner possible. In no case should they be consumed unless they
have been thoroughly boiled a short time before. Any scraps left
should be boiled before being eaten.
The Report of tlie Committee on Disinfection of the American Public
Health Association, Baltimore, 1885, recommends : —
For spore-bearing bacteria {e.g., anthrax) —
1. Combustion wherever possible. 2. Steam under pressure at
110° C. for ten minutes (not long enough). 3. Boiling for an hour.
298 DISINFECTION AND DISINFECTANTS.
4. Chloride of lime, 4 per cent, solution (almost inert unless acidified,
see p. G4). 5. Mercuric chloride-, 1 in 500.
For non-spore-bearing bacteria {e.g., cholera) —
1. 'Five. 2. Boiling half an hour. 3. Dry heat at 110° for two
hours. 4. Chloride of lime, 1 to 4 per cent. 5. Soda chlorinata (p. G3),
5 to 20 per cent, (also almost inert unless an acid is added). 6. Mer-
curic chloride, 1 in 1,000 to 1 in 4,000. 7. Phenol, 2 to 5 per cent.
8. Sulphur dioxide for twelve hours, until there is 4 per cent, in the
air, preferably moist (see p. 92). 9. Cupric sulphate, 2 to 5 per cent.
10. Zinc chloride, 4 to 10 per cent.
Quarantine. — The arguments for and against quarantine, as compared
with our system of port sanitary inspection, cannot be discussed at
length here. Quarantine has been described as an elaborate system of
leakiness, and our English method seems to be as effective, without its
hardships. In a commercial country, rigid quarantine regulations
would be fatal to all interchange of commodities, whilst, if partial
measures are adopted, there is danger to be feared from laxity on the
part of the local authorities, who may rely on these partial measures
ii% being complete. With infectious diseases like cholera, in which the
period of incubation is about fifteen days, it is possible for a person to
arrive in this country from the Continent and pass the port inspection
before any symptoms of the disease are manifest. It is therefore im-
portant that the local authorities throughout the country should have
adequate provision for dealing with such sporadic cases, and medical
officers of health receive special instructions from the Local Government
Board when there is any likelihood of such cases reaching this country.
In August, 1894, special regulations of this character were issued,
and diarrhoea was scheduled as an infectious disease which might be
reportable to the local sanitary authority. Special beds at such times
are arranged for by the Metropolitan Asylums Board and other author-
ities, and instant removal of suspected cases to the various hospitals is
enforced.
At the international conference held in Paris in 1894, the following
precautions were agreed upon : — The convention regulates the pilgrim
ships from India and Oceania, and the sanitary and police rules under
which they shall be ; it provides for the watching and care of pilgrims
in the Bed Sea, and for the protection and sanitary rules of the places
of traffic in the Persian Gulf. The carrying out of the regulations are
to be entrusted to a commission, sitting in Constantinople, to which
very great powers are committed. The internal sanitation of Mecca
itself is left for the present to the management of the Sultan, to whom
strong representations have been made.*
♦ Brit. Med. Joum., April 28, 1894.
METHODS OF ANALYSIS. 299
Prof. De Chaumont, of Netley Hospital, held that quarantine regu-
lations were absolutely useless, interrupted business, and delayed
travellers, without doing any real good.*
The French quarantine legislation is very prolix, although confined
to three maladies — plague, yellow fever, and cholera. Among the
precepts is frontier quarantine. For the regulation of maritime quar-
antine, which apparently is the only form possible at the present day,
the coast is divided into eleven districts, each with a medical officer
and proper staff'. Each port has an office with agents and subordinates.
The control is in the hands of district sanitary councils, who, with the
prefects, prepare reports for the Minister of the Interior.
Italy is the country in which quarantine is most rigid, being in the
highway to the Levant and India, although cholera almost always
travels in one well-marked course — through Russia and Germany to
Hamburg, and thence to England and France. The chief difference
between the English system and strict quarantine is that ours is only
rigidly enforced in times of special danger. It has therefore a chance
of being loyally carried out, whereas quarantine is a continual vexatious
obstruction and is frequently evaded*
CHAPTER XV.
METHODS OP ANALYSIS.
A. Bacteriological Methods : Errors to which these methods are exposed —
Conditions to be observed — Detennmation of the Antiseptic Value — L Of
Antiseptics in Solution — Wynter Blyth's Method for Sewage Antiseptics —
Precautions necessary in these Tests — II. Of the Vapours of Volatile Liquids
— Chamberland and Klein's Methods — III. of Gaseous Antiseptics. Deter-
mination of the Germicidal Value : Relative Value of the Culture and
Inoculation Tests — Examination of Disinfectants in Solution — Dilution
Methods of Sternberg and Wynter Blyth — Thread Methods — Examination
of Gases and Vapours — Fischer and Proskauer's Apparatus. B. Chemical
Methods : Necessity of Analysis — Requirements. Chloride of Lime : Pre-
paration of Standard Solutions and Titration. Sulphurous Acid and
Sulphites. Peroxide of Hydrogen. Boric Acid. Metals. Permanganate.
Phenol : Estimation of Water— Of Phenol by Bromine— Of Cresol — Examina-
tion of Tar Oils — Carbolic Powders — Hager's Glycerine Test — Carbolic Soaps
— Salicylic Acid and other Preservatives in Foods— Tests for Thymol, Naph-
thol, &c. — Medicated Wools.
In order to ascertain the antiseptic or disinfectant value of a given
substance it is necessary to ascertain its effect upon known organisms
* Sanitary Congress, Glasgow, 1883.
300 DISINFECTION AND DISINFECTANTS.
under known conditions. In dealing with commercial products it is
always desirable to ascertain their chemical composition and the rela-
tive amount of the active ingredients present. A full analysis is in
many cases of value, since there is abundant evidence for the belief
that when an active substance is mixed with others the germicidal
value of the mixture is modified. It is impossible to explain the
extraordinary results which have been obtained when two or more
chemical substances have been used together in any other way. The
probable cause of this phenomenon is the selective afiinity which
different micro-organisms exhibit towards different chemical com-
pounds, so that, in addition to the cumulative effect of the several
constituents present, there is a further toxic effect produced by their
simultaneous action.
A. BACTERIOLOGICAL METHODS.
The principles which underlie the methods employed in the bac^
teriological investigation of the value of antiseptics and disinfectants
are of extreme simplicity. The conditions under which the deter-
minations of efficiency are made have, however, a very great influence
in modifying the results obtained, and unfortunately sufficient care
has not, in the past, been taken to specify the conditions of experi-
ment with exactness, nor has it been recognised that the relative
values given for the efficiency of antiseptics and germicides are only
to be accepted for the given experimental conditions. While the
experimental methods employed have had general resemblance, they
have varied infinitely in details, so that the results obtained by different
observers are very rarely strictly comparable. The danger of neglect-
ing the conditions is especially evident when attempts are made to
apply certain experimental results to the actual practice of disinfection.
The earliest investigations were chiefly directed to ascertain the
antiseptic value of various agents by observing their preservative
action on putrescible animal and vegetable infusions. To the in-
fusions, sterilised by boiling, various proportions of the antiseptic
were added, and the dose necessary to prevent putrefaction, or the
period during which putrefaction was averted, was noted. The in-
fusions were exposed to the air and compared with similar infusions
untreated with the antiseptic. The materials used as tests were very
various such as beef-broth, milk, urine, infusions of hay and turnip,
or pastes made of bread, potato, <fec. The occurrence of smell and
turbidity indicated the failure of the antiseptic to prevent decomposi-
tion. The converse experiment, which was a crude attempt to
determine the germicidal value of the disinfectant, was also employed.
A fluid in which putrefaction was already well established was treated
METHODS OF ANALYSIS. 301
with the antiseptic in known proportions for a known time, and drops
of the putrescent fluid were then used to infect fresh sterile, but
putrescible, media. If these materials decomposed it was evidence
that the antiseptic had failed to sterilise the original fluid. The errors
to which these methods are exposed are —
1. An unknown mixture of micro-organisms is experimented with.
It has been abundantly shown that an antiseptic has very varying
effects on varying microbes. 2. The presence or absence of spores in
the inoculating mixture is unknown. 3. When the inoculation is left
to aerial contamination the time of infection is not known. 4. The
infecting mixture may not be identical in the experimental and control
media, 5. Odour and turbidity cannot always be relied upon to
indicate the first occurrence of microbic growth. 6. In conducting
experiments in which the already putrescent fluid is used to inoculate
fresh media it is impossible, since it is not known what varieties of
organisms are present in the inoculating fluid, to be sure whether the
secondary growths are caused by the inoculation or are the result of
accidental contamination. Koch in his classical researches on the
value of antiseptics pointed out these objections, and insisted that the
experiments should be made with pure cultures of microbes, whose
condition as to spore formation was accurately known and which could
be used to artificially inoculate the test fluids with a known organism.
Many pitfalls have since been discovered, but accurate experimental
work dates from these researches.
The bacteriological examination of antiseptics and disinfectants is
directed to ascertain —
1. What retarding or inhibitory influence the agent exercises on
the growth of a specific micro-organism — i.e., what is its antiseptic
power. 2. What effect it has in diminishing the virulence of patho-
genic germs. 3. In what dose and in what time it will cause the
death of the microbe ; what is its germicidal value. Modifications of
virulence under the action of antiseptics, though most important, have
only been determined for a small number of micro-organisms. For
practical purposes the desirable end is to cause the death of the
infective agent, not simply to modify it. The experimental methods
vary according to the physical condition of the disinfectant, whether
it is employed as a solution or as a gas. Though solid antiseptics aro
employed it is only after solution that they are effective. The relative
efficiency of antiseptics and disinfectants is expressed in terms of the
dose and the time of action required to produce a given effect.
302 DISINFECTION AND DISINFECTANTS.
DETERMINATION OP THE ANTISEPTIC VALUE.
I. Examination of Soluble Antiseptics in Solution. — (a) A series of
flasks or test-tubes containing suitable culture fluids is prepared. To
certain of these flasks known quantities of the antiseptic to be tested
are added, while others are left as control flasks. After sterilisation
the flasks are inoculated with the test organism and placed under
suitable and similar conditions of temperature, aeration, &g. If the
maximum antiseptic power is to be measured, then the conditions
under which the flasks are placed must be those most favourable to
the growth of the organism. As the only variable factor in the two
series of flasks is the presence or absence of the antiseptic, any retarda-
tion or inhibition of growth must be due to this variant. The
occurrence of growth is determined by changes in the appearance
of the media and by microscopic examination. (6) Wynter Blyth *
suggested a method, intended chiefly to gauge the value of an,
antiseptic for sewage purification, in which the proportion of microbes
remaining alive after a given time of action of the antiseptic is esti-
mated by culture and enumeration of colonies. Sewage or sewage-
contaminated water is treated with a known proportion of the
antiseptic, and at varying periods known volumes of the mixture are
withdrawn and inoculated into definite volumes of liquefied gelatine
medium. After thorough mixing plate cultures are made in Petri
capsules. The capsules are placed under suitable conditions, and the
number of colonies which develop are counted. If parallel experi-
ments are made with two or more antiseptics the relative efficiency is
in inverse proportion to the number of colonies found in the cultures.
In this method it is assumed that the number of organisms inoculated
is approximately equal. The plan has the usual disadvantages attach-
ing to the gelatine plate method.
Precautions. — If the antiseptic is volatile the culture fluids must be
first sterilised by heat, and then the antiseptic added by means of a
sterilised pipette. It must not be assumed that because growth does
not appear so readily in the flasks containing the antiseptic as in the
control, that therefore the proportion of antiseptic is sufficient to
arrest growth. The flasks should be kept for not less than two weeks
{Sternherg), as after long periods of retardation the restraining power
often breaks down and copious growth takes place. The principal
factors which cause variations in the efficiency of the antiseptics are —
(1) Change in tlie Microbes experimented with. — Certain microbes
have a peculiar tolerance towards certain antiseptics— e.<7., B. typhosus
and iodine trichloride. Others are much aflTected by the acidity or
* Proc. Roy. Soc, 1886.
METHODS OP ANALYSIS. 303
alkalinity of the medium, and the change in reaction due to the added
antiseptic may be the cause of variation.
(2) Change in the Medium. — A diminution in the nutritive value of
the medium will apparently increase the antiseptic power. The chief
eflfect of change of medium is, however, due to changes which occur
in the chemical reactions between the antiseptic and the constituents
of the medium. All antiseptics which form precipitates with albumens
have their efficiency diminished when an albuminous fluid is employed
— e.g., HgClj, AglsTOg, &c.; and, similarly, any substance which by
precipitation diminishes the available amount of soluble antiseptic
present — e.g., NaCl with AgNO^, or HoS with HgClo — will greatly
diminish the apparent activity of the agent.
(3) Change of Temperature. — This factor acts in two opposite direc-
tions. An increase in temperature up to the optimum temperature
of growth of the microbe is favourable to the micro-organism, but
the rise of temperature also increases the activity of the antiseptic.
Which factor will prove most active can only be determined ex-
perimentally.
II. Examination of the Vapours of Volatile Fluids. — The principle of
the methods employed is similar to that described for solutions.
(a) Chamberland's Method.* — A U-tube similar to those used for
anaerobic cultures is employed. Into one limb the volatile fluid is
aspirated, into the other the inoculated culture medium. The tubes
are then sealed. The space above the fluid becomes saturated with
the antiseptic vapour. The occurrence of growth is determined as
before.
(h) Klein's Met/iod.i — Short and wide tubes are prepared containing
sterile agar medium with the usual sloping surface. The volatile
antiseptic is placed on the side of the tube opposite the agar, and the
excess runs to the bottom of the tube. The agar is then inoculated in
its upper part, well away from the fluid and the tubes, tightly plugged
and, if necessary, capped with an india-rubber cover, and kept at a
suitable temperature. The efficiency of the antiseptic is evidenced by
the absence of growth.
III. Examination of Gaseous Antiseptics. — The methods will be
described when dealing with the germicidal value of disinfectants.
DETERMINATION OF THE GERMICIDAL VALUE.
Principle of the Methods. — The disinfectant is allowed to act for a
known time in a known strength on a pure culture of a micro-organism.
The disinfectant is then removed, and the death or continued vitality
* Ann. Inst. Pasteur, vol. L, p. 163.
t BrU. Med. Joum., 1894, vol. i., p. 375.
304 DISINFECTION AND DISINFECTANTS.
of the organism determined by (1) the capacity to produce fresh cul-
tures, or (2) the power to produce a pathogenic effect when inoculated
into susceptible animals. The objects to be attained are : — (1) The
perfect exposure of the organisms to the action of the disinfectant.
In order to ensure this condition the organisms should be in suspension
or exposed in a very thin layer, and care should also be taken that
the microbes are not coated with any layer, such as oil, which would
mechanically prevent the action of the disinfectant. (2) The perfect
removal of the disinfectant from the organisms whose vitality is to be
tested. The various modifications in the experimental methods are
chiefly directed to this end. Seppert has shown the great difficulty
that there is in freeing the organisms from adherent material, and also
the enormous influence that infinitesimal doses of disinfectant may
have in retarding or hindering growth. This is especially marked
with regard to the germination of spores. Seppert experimented with
anthrax spores and mercuric chloride, and demonstrated the different
results obtained according as the mercuric chloride was simply washed
away or removed by precipitation with ammonium sulphide. He also
showed that the amount of mercuric chloride required to prevent the
development of spores which had been exposed to the action of the
disinfectant was very much less (only 1 : 2,000,000) than the proportion
required to produce the same effect on spores which had not been so
exposed, and that the longer the exposure the less was the amount
required.
Relative Value of the Culture and Inoculation Tests in the Deter-
mination of the Vitality of the Disinfected Organisms. — Opinions differ
very considerably on this point. There can be little doubt that for
the determination of the continued vitality of the organism the culture
test is the more delicate, and for this reason, as well as for the con-
siderations of economy and convenience, it is the one usually employed.
For determining alterations in the virulence of the microbes, the in-
oculation test is the only one available. The great objection to the
animal inoculation test is the fact that exposure to the disinfectant so
modifies the virulence of the organisms that they no longer produce
their pathogenic effect, though they retain their vitality. There is
no certainty that these non-virulent organisms may not give rise on
germination to virulent growths, and therefore, for practical purposes,
the death rather than the alteration of the organisms is to be desired.
An animal which has been used for an inoculation test cannot be
employed a second time even if it has apparently not suffered any ill
effects, as a condition of insusceptibility, a vaccination, may have been
produced by the first inoculation.
Examination of Disinfectants in Solution. — Dilution Methods. — There
METUODS OF ANALYSIS. " 305
are several methods, varying in detail, in which, after exposure of the
organisms to the action of the disinfectant, a small portion of the cul-
ture is removed and inoculated into a relatively large volume of a
nutrient medium. The dilution thus brought about is trusted to
reduce the amount of the disinfectant carried over below the amount
which would cause inhibition of the growth. If thought advisable, a
second inoculation, with consequent further dilution, may be made
from a primarily infected culture. It is obviously important that
fluid media should be used for the culture test, or otherwise the re-
moval of the disinfectant is not secured.
(a) Sternberg's Method. — A known volume (5 c.c.) of the standardised
disinfectant is added to an equal volume of a fluid (bouillon) culture of
the micro-organism. After exposure for a given time a small portion
of the mixed culture is withdrawn and inoculated into a suitable
culture medium. The results are calculated as produced by a disin-
fectant of one half the strength of the solution added to the culture.
Either the time of exposure or the strength of the solution can be
made the variable factor.
(6) The Drop Method ( Wynter Blyth). — Sterilised distilled water is
infected with the test organism, and measured volumes of the infected
water are added to known volumes of the disinfectant. After a given
time a drop of the mixture is added to 10 to 20 grammes of liquefied
gelatine medium, and the growth watched. Bouillon is a more suit-
able medium, as many pathogenic germs grow slowly at temperatures
at which gelatine remains solid and retains its distinctive advantages.
Bouillon has also been shown in Miquel's experiments to give greater
opportunity for the growth of organisms whose vitality has been re-
duced than the solid media. If it is desired to use micro-organisms
from cultures in solid media, the growth is scraped off with a wire
And suspended in sterile distilled water. Such suspensions, filtered to
remove flocculi, are employed advantageously, because the disturbing
effects of varying media and the presence of precipitates are avoided.
The Thread Metliod. — This is often known as Koch's metliod, as it
was employed by him in examining the action of antiseptics on the
spores of Bacillus anthracis. Sterilised silk threads were soaked in
cultures containing anthrax spores (or, better, suspensions of spores
in sterile water) and dried. The threads were allowed to hang in the
disinfectant for the desired time and afterwards withdrawn, washed
in sterile water, and inoculated either into animals or fresh nutrient
media. Koch employed solid media for his inoculations. This method
ias been much used, and possesses the advantage that the disinfectant
can be got rid of by washing. If fluid media are employed for the
test cultures it possesses also the advantages of the dilution methods.
20
306 DISINFECTION AND DISINFECTAllTS.
When employed for non-spore-bearing organisms the intermediate
drying should be omitted, as that itself will diminish the vitality
of many organisms in the vegetative form. Suspensions in sterile
water are preferable to fluid cultures in which to soak the threads, as
the (often albuminoid) medium forms a coating when dry which
protects the organisms. In all cases control experiments must be
made in which threads are treated^ just as are the test threads, except
that sterile water is substituted for the disinfectant. Instead of
threads platinum wires have been employed, and Blyth has suggested
the use of small plugs of sterilised cotton wool attached to capillary
glass rods by means of sealing wax. There must be some difliculty
in securing efficient sterilisation of these mops.
Examination of Gases and Vapours. — The method of Chamberland
described above is equally convenient for the determination of the
germicidal action of the vapour of essences, volatile oils, &c. Instead
of an inoculated medium a suspension of a given microbe is aspirated
into one limb of the tube, and after exposure for the desired time a
drgp of the culture is withdrawn for inoculation. It must be remem-
bered that unless the gas or vapour is soluble in water only the surface
is exposed to the action of the disinfectant. When it is not required
that the proportion of a gaseous disinfectant present should be known,
or when the eflfect of a saturated atmosphere is to be tested, the micro-
organisms, either on threads, or in very thin layers on sterile cover
glasses, or on sterile filter paper which has been dipped into cultures
or water suspensions and allowed to dry, may be exposed under a bell
jar to the action of vapour evolved from a capsule of the volatile
disinfectant also placed under the jar. Test-tubes Avitli bulbous ends,
such as are used for potato culture:-;, may also be conveniently employed,
the disinfectant being placed in the bulb. The threads, cover glasses,
&c., are used to inoculate culture media either directly or after
washing.
Fischer and Froskauer^s Method* — These two observers made a
series of very complete investigations on the action of several gaseous
disinfectants, including sidpliurous acid and the halogens. Their
apparatus consisted of a 20-litre very wide-mouthed jar, through
whose stopper tubes for the delivery and exit of gas were passed.
Both tubes were provided with taps, and the exit tube was furnished
with a series of absorption bulbs. A thermometer also passed through
the stopper. The centre of the stopper was itself perforated and
fitted with a large india-rubber cork, through which passed a glass
rod, carrying a series of glass shelves on which the objects to be
disinfected could be placed. Such an apparatus permits of the ex-
• Milt, ausdem K. Gesund., Bd. II., 1884.
METHODS OF ANALYSIS. 807
posure of test objects to the action of the disinfecting gas under the
most diverse conditions, and also allows the amount of the gas present
in tlie apparatus to be determined.
Most of the conditions wliich affect the determinations of anti-
septic and germicidal values have been already considered, but
there is one factor which is not under experimental control, and
which imparts an element of uncertainty into the results. This
factor is the variation in vitality and resistance of different specimens
of the same micro-organism. In any culture there is a rather wide
range of variability in the individual organisms, and this range of
variability is increased if the cultures are not of the same age and
grown under the same conditions on the same medium. The age
and nature of the culture should always be specified, and this
element of variability eliminated so far as possible by multiplying the
experiments. It is obvious that the methods detailed above must be
varied as the problems to be solved differ ; but the principles to be
kept in view, and which have been insisted upon, are constant ; while
the errors to be avoided are also very similar in every investigation.
B. CHEMICAL METHODS.
As already pointed out, a full chemical analysis of a given disin-
fectant is desirable, owing to the influence of foreign substances upon
its germicidal value. In many cases in which the active ingredient is
volatile, it is necessary to test from time to time the chemical strength
of the material, as there have been several instances in which neglect
of this precaution has allowed the use of a disinfectant which has been
found to be of no valne in preventing the spread of the infection
through deficiencies in its activity having arisen either by storing or
the culpability of the vendor. The methods of analysis obviously
depend on the kind of substance to be employed, and may frequently
involve much labour and skill. It is extremely important, however,
that all disinfectants should be purchased on analysis, and that samples
should be taken from bulk after the order has been executed, in order
that the medical ofiicer may be assured that the material is equal in
strength to that which has been prescribed. It would exceed the
scope of this chapter if all the methods which might be of service were
described at length. A selection has therefore been made of some of
the quantitative tests which may be of use in identifying an unknown
disinfectant.
For any exact analysis, a laboratoxy, and such special skill, know-
ledge, and training as no engineer or medical man can possess, is
indispensable; hence such questions should be referred to a competent
chemist. But there is always an advantage in being able to quickly
308 DISINFECTION AND DlSINFECTANl^.
and roughly determine factors like the strength of chloride of lime, «kc.
It has already been pointed out that disinfection in ignorance is almost
worse than no disinfection at all.
In the following sketch for the simplest processes for testing the
most important disinfectants, a knowledge of elementary quantitative
analysis is assumed. Further details will be found in the various
manuals on analysis. The following is a typical example of methods
of procedure : —
Chloride of Lime. — As already explained (p. 63), the available
chlorine is that existing as hypochlorite, Ca(C10)o ; this easily breaks
up into chloride, CaClo, and free oxygen, O^. The usual way of esti-
mating it is by standard solutions of iodine and arsenlous acid, using
starch as an indicator. The latter is not permanently blued until all
the arsenious acid has been oxidised to arsenic acid.
All volumetric solutions are usually made decinormal — i.e., one-tenth
equivalent in grammes of the active agent in one litre ; then 1 c.c. is
equivalent to 1 c.c. of another.
Iodine Solution. — Dissolve 12 "65 grammes of iodine, mixed with
about 20 grammes of potassium iodide, in a litre of water.
Arsenious Solution. — 4*942 grammes of pure arsenious oxide and
20 grammes of sodium bicarbonate are dissolved in a litre of water.
Take 10 grammes of chloride of lime, triturate it in a mortar with
successive small quantities of water, and transfer the whole gradually
through a funnel into a stoppered litre flask. For each determination
take out 10 c.c. of the well-shaken turbid fluid (to decant the clear
solution gives a lower result — Fresenius), equal to a decigramme of the
powder. Add from a burette the arsenious solution in slight excess —
i.e., until a drop ceases to produce a blue spot on ozone paper (KI and
starch). Then add fresh starch paste, and run in iodine solution from
another burette until there is a slight permanent blue colour. The
number of cubic centimetres of iodine solution required gives the
number of c.c. of arsenious solution that have been added in excess ;
subtract this from the total added, and the number of c.c. of the
standard arsenious solution which are equivalent to a decigramme of
the chloride of lime is obtained.
Each c.c. of the decinormal arsenious acid is equal to yj^^tj- of
an equivalent of available chlorine, or -00354 gramme.
The iodine solution should have its strength determined by the
arsenious acid before each series of experiments. It keeps fairly well
in the dark.
The same method can be used for the examination of chlorinated
soda and potash, Hermite liquid (p. 67), bromine and iodine water,
tincture of iodine, chlorine water, and indeed most oxidants.
METHODS OP ANALYSIS. 309
Sulphites and Sulphurous Acid. — The solution must be very dilute
containing not more than 0'05 per cent, of SOg {Bun8en)y then iodine
converts sulphurous acid into sulphuric. If sulphite powders are
examined the method is exactly as with chloride of lime, omitting the
arsenious solution, but adding starch paste and running in iodine
solution until the permanent blue tint is obtained. 1 c.c. of iodine
= -0032 gramme of SOo.
The same process answers for most reducing agents, such as sul-
phuretted hydrogen, &c., but not for ferrous sulphate, which should
be determined by standard permanganate.
To test for the presence of sulphites in food, two portions should be
strongly acidified by dilute pure sulphuric acid, and over each a piece
of paper moistened with lead acetate should be suspended. To one
should be added some pure granulated zinc, so as to obtain a slow
evolution of hydrogen. If much frothing occurs, water must be added.
The two are left for half an hour in a warm place. If the lead paper
be blackened only over the one containing the zinc, it proves the pre-
sence of sulphite ; if both papers be blackened, the blackening is due
to other sulphur compounds, and the test is worthless.
Peroxide of Hydrogen is marked in commerce " 10 or 20 volumes,"
meaning the number of times its volume of oxygen that is given off
when it is treated with peroxide of manganese. An easy way of
ascertaining this is as follows : —
A flask with cork and delivery tube is arranged to deliver the gas
into a graduated measuring tube holding 200 c.c. filled with water
and inverted in a basin or pneumatic trough. 10 c.c. of the hydrogen
peroxide solution are measured into the flask. About a gramme of
finely-powdered manganese dioxide is wrapped in a piece of paper,
slipped into the flask, and the cork at once replaced. On shaking, the
available oxygen is evolved. By warming the flask the last of the
oxygen is removed, and is then measured. It can, of course, be calcu-
lated into weight. A rough idea of the quantity may also be obtained
by adding to the diluted solution in a test-tube a few drops of
potassium dichromate, then dilute sulphuric acid and ether. The
intensity of the purple colouration of the ether layer is compared with
that produced by a sample of known strength. This cannot be recom-
mended except as a qualitative test.
Boric Acid. — A quantitative determination is tedious, but its pre-
sence in milk, &c., may be ascertained as follows : — Evaporate a large
measured quantity (say 250 c.c), rendered alkaline by lime water to
dryness, and burn to ash. Warm the ash for some time with a little
water containing a drop of ammonium chloride, and filter. Acidulate
the filtrate just faintly with hydrochloric acid, and spread it on a sheet
310 DISINFECTION AND DISINFECTANTS.
of turmeric paper specially made as follows : — Digest turmeric root
with rectified spirit, filtei', float a» sheet of writing paper oa the extract,
then drain and dry it so that it has a uniform clear yellow coating.
The spot is carefully dried over a water-bath ; if boric acid be present
there will be a rose-red colouration, turned dark dull blue by weak,
soda solution.
A few metals can be determined by volumetric processes, but as a
rule, methods of precipitation and weighing are adopted. It will be
rarely necessary or feasible to undertake these, as solutions of known
strength can easily be made by dissolving the calculated quantities of
the salts bought on a guarantee or on the analysis of a chemist.
Permanganate (Condy's Fluid). — A known volume of a decinormal
solution of oxalic acid is placed in a beaker or porcelain dish, rendered
strongly acid with dilute sulphuric acid, and the permanganate solu-
tion, properly diluted, run in from a burette until a permanent pink
tinge is produced. The reaction is —
5H2C2O4 + KgMnaOs + H2SO4 = K2SO4 + 2MnS04 + IOCO2 + 8H2O.
Therefore 5 equivalents of oxalic acid require for oxidation 1 equi-
valent of permanganate, equal to 5 atoms of aA'ailable oxygen.
Phenol. — Water is estimated by shaking the sample in a graduated
tube with half its volume of a saturated solution of common salt.
The diminution of volume of the phenol indicates the amount of water
present. "Calvert's No. 1" contains none, crude acids often contain
10 to 17 per cent. Anhydrous cresol shaken up with three volumes of
brine gives an increase of volume of about 5 per cent. If the cresol
contains water, its volume either does not alter, or decreases slightly.
To Determine the Phenol. — Shake up bromine with water at 20° C*
To determine the phenol-equivalent of the bromine water, a sample of
Calvert's No. 1 acid (crystals) is boiled for a short time to remove
traces of moisture, 0-25 gramme weighed into a well-stoppered flask
and dissolved in 100 c.c. of water, the bromine water run in from a
stoppered burette, with constant shaking, until there is a good excess,
as shown by the colour. After half an hour's standing, if the excess
has disappeared, more bromine must be added, and the mixture again
shaken and allowed to stand ; the total amount added must be care-
fully noted, excess of potassium iodide is added, and the amount of
liberated iodine ascertained by standard thiosulphate and starch in the
well-known manner. This free iodine corresponds to the bromine in
excess ; deduct this from the total bromine added, and the amount of
bromine water necessary to precipitate 0*25 gramme of pure phenol is
* Such a solution keeps better than water saturated with bromine in the cold,
and may be preserved in well- stoppered bottles in the dark.
METHODS OF ANALYSIS. 311
obtained. It is then easy to calculate the phenol-equivalent of each,
cubic centimetre of the bromine solution.
CeHs.OH + 3Br2 = CcHaBrg.OH + 3HBr.
The operation repeated with the sample under examination gives the
phenol strength.
Samples containing cresol and higher phenols would require pro-
portionately less bromine, so the result would be lower than the
truth, if the bromine equivalent is calculated to phenol. Another
process consists in determining the solidifying point of a mixture by
cooling it in a narrow tube and adding a minute crystal of pure
phenol to aid the solidification. The melting point is then compared,
with ready-made mixtures of known composition (or with a table).
It is possible to collect the tribromo-precipitate on a filter paper.
Tribromophenol is crystalline, tribromocresol and the others are liquid ;
hence the latter soaks into the paper, and the two can be separately
weighed. The liquid portion should be calculated as cresol and higher
homologues.
Fractional distillation of the phenoloids gives doubtful results as
their boiling points are too near one another.
Tar Preparations. — The ingredients of these may be divided into
four groups : —
1. Neutral bodies not combining with acids or alkalies,, divided
into —
(a) Light oils, containing benzene and the homologues.
{h) Heavy oils, containing naphthalene, anthracene, &c.
The antiseptic value of these is slight. They are classed as neutral
tar oils.
2. Basic bodies, combining with acids — e.g., aniline, pyridine, <fec.
As their antiseptic value is high they may with advantage be present
in disinfectant fluids. The commercial importance of aniline has led
to this group being extracted in making phenol and cresol prepara-
tions. Hence there has been a reaction in favour of crude coal-ttir
preparations, instead of the purely phenol compounds that were
formerly almost exclusively in vogue, although the neutral bodies in
the former are undoubtedly of little value.
3. Pitenols, soluble in alkalies, but not really acid bodies (p. 149).
The valuation of these preparations is based on the proportions of
these constituents.
A. 10 c.c. of the oil are taken in a graduated tube, 20 ac of 10 per
cent, caustic soda added, and the whole well shaken, and allowed to
stand. The phenoloids dissolve, while the neutral (and basic) sub-
stances collect as an oily layer; below, if they are heavy oils; at the
312 DISINFECTION AND DISINFECTANTS.
top, if they are light oils. If they will not separate distinctly, which
often happens, add 10 c.c. of petroleum ether and shake, measure the
amount of the mixture and subtract the ether. The result is only
approximate, but for ordinary purposes this method is considered
sufficient, the volume obtained being returned as the neutral tar oils
present.
B. For a more exact examination a larger quantity must be taken,
50 or 100 grammes of the original liquid, treated with soda as
above, and the two liquids separately examined, after measuring their
quantity.
(a) The portion insoluble in soda is evaporated below 100° C. to
remove the ether ; naphthalene and anthracene may crystallise out on
standing, and may be identified by their melting and boiling points.
The liquid which will not crystallise is washed in a graduated tube with
20 per cent, sulphuric acid to remove the bases as sulphates. Notice
again the diminution of volume (result only approximate). The acid
solution is distilled with aqueous potash ; the bases (aniline, pyridine,
&c.) come over and can be tested. If the quantity allows, dry them
by fused calcium chloride, determine their boiling and melting points,
their chemical reactions, and the nature of their platinum double salts.
The portion insoluble in all reagents can be tested by its physical
properties.
(b) The fraction soluble in soda, containing the phenoloids, is frac-
tionally precipitated by successive small quantities of dilute sulphuric
acid, whereby the carbolic acid is concentrated in the first fraction ;
then the melting points of the several fractions are taken, as above
described.
Caxbolic Powders. — In the case of powders made with lime, or others
in which the phenol exists in combination, neither direct distillation,
nor extraction with ether, give a correct result unless the powder is
first acidified. Allen mixes 50 grammes in a large mortar with 5 c.c.
of water, and drops in gradually with constant stirring, so as to keep
down the heat, 50 per cent, sulphuric acid. The addition, which takes
some hours, is continued till a fragment of the powder shows an acid
reaction when moistened with water. If the mixture be pasty, it
must be triturated with sand to make a granular powder. After
standing covered for two hours, it is transferred to a large Soxhlet
tube and extracted with ether or benzene. On distilling ofi" the
solvent below 110° C, the crude tar products are left, and can be
further tested.
To distinguish between preparations made from wood-tar and from
coal-tar is comparatively easy ; in mixtures the identification of the
source (shale oil, blast furnace oil, «kc.) becomes more difficult.
METHODS OF ANALYSIS. 313
1. Coal-tar acids coagulate collodion, B.P., wood creosote does not.
2. A neutral aqueous solution of ferric chloride gives with phenol a
deep violet colour, with wood-creosote a yellowish or greenish-brown tint.
3. Hager's Test. — Thirteen volumes glycerine are diluted with 1
volume water. One volume of the sample to be tested is well shaken
in a stoppered burette with 3 of the diluted glycerine, and allowed to
stand. If the creosote be pure, the volume will remain unchanged.
If reduced, the glycerine layer is drawn off and the reinaining creosote
again shaken with 3 volumes of the dilute glycerine, and the volume-
again observed. The undissolved portion includes the wood-creosote,
but may also contain products from shale or blast-furnace oil ; the
chief distinction lies in the odour. The soluble portion may be diluted?
with water, the coal-tar acids extracted with chloroform, and the latter
separated and distilled off. So separated, the phenoloids from blast-
furnace and shale oils give with ferric chloride a violet-blue colour
changing to brown, instead of a permanent deep violet, as with ordi-
nary phenol.
Sulphuretted hydrogen should be tested for with dilute sulphuric
acid and lead paper. Powders containing it emit an offensive odour,
and are usually excluded by the terms of the contract. Sulphites and
hypochlorites can be determined as at p. 308. With lime bases, the
determination of sulphurous acid is difl&cult. As sulphurous acid
powders oxidise on keeping, it is important to ascertain not only the
"available" sulphurous acid, but also the quantity oxidised to sul-
phuric acid.
It is impossible to give a general process for the detection or esti-
mation of the multitude of organic bodies that have been introduced
for sanitary purposes. It may be mentioned that in the above division
of the tar preparations into acid, basic, and neutral bodies, the follow-
ing substances will appear in the places indicated : —
(o) With the neutral oils : Benzene, naphthalene, anthracene, vase-
line, paraffins, pyrrol, essential oils, thymol, camphors, alcohol, ether,
and neutral bodies generally.
(6) With the bases : Aniline, pyridine, quinoline, ammonia, compound
ammonias, and volatile alkaloids such as trimethylamine, nicotine, &c.
(c) With the acids : Phenol, cresol, &c., resorcin, benzoic, and other
aromatic acids, fatty and resin acids (distinguished by non-volatility
and other physical characters ; resin soap gives a brown colour and is
not coagulated by strong soda solution, thus differing from a fatty
soap).
The specific gravity of crude carbolic acid should be between 1 -05 to
1-065; if it is less it is most likely adulterated with light tar-oil, in
which case the specific gravity is often between 1 04 and 1 04:5.
314 DISINFECTION AND DISINFECTANTS.
Carbolic Acid in Soaps. — Five grammes of the soap are dissolved in
warm water, and 20 or 30 c.c. of 10 per cent, caustic soda added. After
cooling, the solution is shaken witli ether to remove any hydrocarbons
(terebene, camphor, <kc.). The alkaline liquid is next mixed with
saturated brine, which precipitates the soap and leaves the phenols in
solution. It is then filtered, the soap again shaken up with brine
and the washings added to the filtrate, and the liquid made up to
1 litre. 100 c.c. of the solution ( = 0*5 gramme of the soap) are placed
in a separator, acidulated with dilute sulphuric acid, and titrated with
bromine water as at p. 310.
Salicylic Acid and other Preservatives in Foods. — The articles are
cut up if necessary, and extracted, first with two portions of cold, then
with about three of boiling water, separating any fat by passing through
a wet filter, or in some cases by allowing the whole to cool and removing
the layer of fat. The volume of the aqueous liquid should not be un-
duly large. Milk must be coagulated by a little acetic acid and gentle
warming, then filtered and the whey examined. Solutions containing
gummy or viscous matters, or colouring matters soluble in ether, can
be precipitated by neutral acetate of lead filtered, the filtrate freed
from lead by sulphuretted hydrogen, and the latter expelled by
warming. The prepared filtrates should then be neutralised by soda,
evaporated to a convenient bulk, acidified with hydrochloric acid, and
extracted with ether in a separator. The ethereal solution, besides
salicylic acid, will contain any phenol, cresol, benzoic and other aro-
matic acids, thymol, essential oils, ethers, glycerine, perhaps bitter
principles, resins, glucosides, alkaloids, and sugars in traces, lactic and
vegetable acids. If acetate of lead has been used, the resins and
bitters will have been removed. Distil oft' the ether, evaporate the
residue at a gentle heat, dissolve in a measured volume of water, and
divide into several portions. Notice the odour, taste, and appearance,
a,nd apply special tests. If glycerine be sought for, neutralise with
soda, again extract with ether, distil off the ether and evaporate; the
nearly pure glycerine can be weighed and afterwards tested.
In an aliquot part the salicylic acid can be determined by adding
neutral ferric chloride cautiously (iron alum is more convenient), and
imitating the colour in another tube by a standard solution of salicylic
acid.
If phenol or resorcin be present, the comparison must be effected in
alcoholic solution (absolute), with alcoholic ferric chloride. Thus even
1 part of salicylic acid with 800 of phenol may be estimated.* In
testing for resorcin H. Bodde f adds a few drops of sodium hypochlorite
• A. Fajans, Chem. Zeitung, 1893, vol. v., p. 69.
f Nederl. Tydschr. v. Pharm., May, 1889.
METHODS OP ANALYSIS.
(p. 63) to a watery or alcoholic solution of resorcin ; a violet colour,
i-apidly changing to yellow, is produced. On wanning or adding excess,
the liquid becomes dark brown. One part of resorcin in 10,000 of
water will still show this reaction. Carbolic, salicylic, benzoic, and
other allied acids do not give it, but may turn the liquid slightly
yellow on warming. Pyrocatechol (p. 172) turns green, hydroquinone
yellow and red. Another test is to first add liquor ammonite and then
a few drops of the hypochlorite, when the liquid will give a reddish-
violet colour, turning green on boiling. The colour is not taken up
by benzene. The reaction is not shared by salicylic nor benzoic acid,
nor by antifebrin (p. 185), but phenol gives a greenish-blue, partly
soluble in benzene. The colours are changed to red by dilute sulphuric
acid.
Messenger and Vortmann have found that strongly alkaline solutions
of phenol, thymol, /S-naphthol, and salicylic acid admit of estimation
by means of a decinormal thiosulphate solution, using starch as an
indicator in the ordinary way. Each molecule of phenol consumes
6 atoms of iodine, therefore the iodine consumed multiplied by
„^- ^, ,- — ; — ' ^ . ,. K or 0-1235, gives the quantity of phenol. The
759-24 (6 atoms iodine) * ^ J r
process is as follows : — 2 grammes of the phenol are dissolved in water
with about 3 grammes of caustic soda, and the solution diluted to 250
or 500 c.c. 5 or 10 are measured into a flask, warmed to 60° C, and
iodine solution added till the liquid is strongly yellow. On agitation
a bright red precipitate will fall. After cooling, the liquid is acidulated
with dilute normal thiosulphate to ascertain the excess of iodine.
Thymol gives a brownish-red precipitate, and requires no heat. It
requires 4 atoms of iodine, hence the multiplier is 0-2957. From 0-1
.to 0-3 gramme is taken.
^Naphtlwl gives a dirty-green precipitate ; the factor is 0*3784.
The solution must be heated to 60° C.
Salicylic Acid. — At 60° C. the bright red precipitate should not be
formed until the iodine is in excess, and should be increased by acidu-
lation. If too little alkali be present, a yellowish-white precipitate is
formed ; in this case more soda must be added. The multiplier is
0-1813.*
In a mixture of two of these bodies, if the sum of their weights is
known, as well as the iodine equivalent of the mixture, the amounts
of the two constituents can be calculated.
Formalin can be recognised in foods by distilling and proving the
presence of a volatile aldehyde in the distillate by means of a magenta
solution bleached by sulphurous acid.
• Berichte, 1890, p. 2753.
316 DISINFECTION AND DISINFECTANTS.
Medicated Wools. — Mr. Hoseason, in a recent paper on medicated
cotton wool dressings,* drew attention to the immense variation in
the strength of these preparations as found in commerce. The method
of analysis consists in shaking weighed quantities (10 grammes) of the
wools with water (1 litre), and determining the amount of the effective
constituent in the following way : —
1. PJienol, by the volumetric bromine process (p. 311).
2. Boric Acid, by evaporating one-fortieth (25 c.c.) of the solution
to dryness with 5 c.c. of a strong solution of sodium carbonate, the
latter being previously standardised. The loss of carbonic acid was
estimated by weight in a modification of the usual COg apparatus.
The boric acid was thus determined by difference.
3. Mercuric CMoride. — Scherer's method with hydrochloric acid and
decinormal thiosulphate is inapplicable if the quantity of mercury is
small. A colorimetric method based on the depth of the brown colour
with sulphuretted hydrogen may be used. Some results obtained with
commercial antiseptic wool dressings are as follow: —
Carbolic, in five samples : 1-06, 1"07, 0*69, 0*25, 5*08 per cent.
Boric, in five specimens : 36, 21 "6, 27*1, 15"8, 14-4 per cent.
Corrosive Sublimate, in two : none, and 1 in 8,000 to 9,000.
* Chem. and Drug., Feb. 18, 1893.
317
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Proskauer. Ueber SchwefeligsUure. Mittheil a. d. kais. Gesund., i., 234.
Fischer. Ueber Chlor und Brom. Jbid., ii., 228.
■Wolfrhiigel and Proskauer. On SO2. Chem. Centralblait, xiii., 334.
R^veil. On Charcoal. Archives gdndrales de 3Ied., 1S63.
Slater. Investigation of Artificial Mineral Waters. /. 0/ Path, and Bad., I.,
468, 1893.
ORGANIC BODIES.
Andeer. Ueber das Resorcin. Wiirtzburg, 1880.
Fraenkel. Die desinfizirenden Eigenschaften der Kresole. Zeitschri/t fur
Hygiene, vi.
Declat. Manuel de M^d. Antiseptique. L'Acide Ph^nique et ses Composes.
Paris, 1890.
Helbing. Modern Materia Medica. London, 1891.
Shoemaker. Ointments and Oleates, especially in Diseases of the Skin. London,
1890.
Frankland and Ward. Report on the Cresols, 1893 (abridged in J. Soc. Chem.
Industry, 1,051, 1893).
Allen. Commercial Organic Analysis.
Th. Wehl. A Sanitary Investigation of the Coal-tar Colours, translated-.
London, 1892.
Farquharson. Ptomaines and Other Animal Alkaloids. London, 1892.
Wernicke. Effect of Tobacco on Bacteria. Centr.f. Bakteriol., xv., 898, 1894.
Salicylic and Benzoic Acids.
Salkowski. Ueber die Antiseptik Wirkung, &c. Berlin, klin. Wochenschrift, 22,
1875.
British Medical Journal, II., 1,438, 1887.
Portele. Landiv. Versuchs. Stat., xxvii., 143.
Dunstan and Block. /. Chem. Society, April, 1891.
Prohlich. Salophen and dessen Therap. Anwendung. Berlin, 1892.
BIBLIOORAPHlf. 321
LIGHT.
Downes and Blunt. Researches on the effect of Light on Bacteria. Proc. Boy.
Soc, xxvi., 184, 1877.
Downes and Blvint. Influence of Light on Protoplasm. Ibid., xxviii., 199, 1878.
Tyndall. Influence of Light on Organic Infusions. Ibid., xxviii., 1878.
Tjrndall. Arrestation of Infusorial Life. Nature, xxiv., 466, 1881.
Jamieson. Infl. of Light on Bacteria, /ftfrf., xxvi., 1882.
Duclauz. Infl. de la Lumi^re du Soleil. Comptea Rendua, c. 119, and ci. Aug. 5,
1885.
Arloing. Infl. de la Lumi^re sur Bacillus Anthracis. Ibid., Feb. 9, Aug. 24,
and Aug. 31, 1885.
Downes and Blunt. Answer to Criticisms. Ibid., xl., 242, 1886.
Roux. Action de la Lumiere et de I'Air. Ann. Inst. Pasteur, i. , 455, 1887.
Gaillard. Influence de la Lumifere. Lyon, 1888.
UflFelmann. Hyg. Bedeutung des Sonnenlichtes. 1889.
FanzinL Azione della Luce. Rivista d'Igiene, 1889.
Santori. La Luce. Boll. d. Accad. Med. di Roma, xvi., 1889-90.
Momont. Ann. de I' Inst. Pasteur, vi., 21, 1892.
Geissler. Wirkung des Lichtes. Cenlr./iir Bakteriol, xii., 161, 1892.
Buchner. Einfluss des Lichtes. /bid., xi., 781 ; xii. 217, 1892; and Archiv. f.
Ihjg., 1893.
Marshall Ward. Proc. Roy. Soc, liii., 310, 1893.
Procacci. Influenza della Luce Solare. Annali della Inst. d'Igiene di Roma, iii.,
437, 1893.
Palermo. Azione della Luce Solare sulla Colera. Ibid., iii., 463., 1893.
Khmelevsky. Influence of Light on Pyogenic Microbes. Brit. Med. Joum.
No. 1,740, p. 71, 1894.
HEAT.
Rapport de Commission sur les Appareils i disinfection par I'Air chaud. Revue
d" Hygiene. Paris, 1881.
Parsons. Disinfection by Heat. Report Med. Officer of Health to London Oovem-
ment Board, 1881.
Parsons. Extracts from do., 1886.
FOOD.
H. Vogel. Food Preservatives. Deutsche Viertel.f. 6^. Ges., 402, 1880.
Weber. On Food Preservatives. J. Amer. Chem. Soc, xiv., 1892.
Bouvier. Le Lait. Paris, 1893.
WATER.
{Besides numerous references under Bacteriology.)
Rivers Pollution Commission Reports, from 1868.
Percy Frankland. Water Purification, its Biological and Chemical Basis. Tran».
Inst. Civ. Engineers, 1886.
Local Government Reports. London Water Supply: Effect of Filtration. 188&
and following years.
P. Frankland. Filtration of Water for Town Supply. Trans. Inst. Civ. E., 1886.
Sir F. Bolton. Manual of London Water Supply.
21
322 DISINFECTION AND DISINFECTANTS.
Plagge and Proskauer. Sand Filtration. Zdt. f. Hyg., ii., 401, 1887.
Gartner. Hygienische BeschaffenheiJ des Trinkwassers. International Congress
of Vienna, 1887.
J. Koenig. Reinigung der Abwasser. Ibid.
Fraenkel and Piefke. Filtration. Zeit.f. Hyg., viil, 1, 1890.
Ste ilisation of Water. New York Med. Record, No. 1,023, p. 680, 1890.
Lefftnann and Beam. Examination of Water for Sanitary and Technical Pur-
poses. London, 1891.
Floyd Davis. Handbook on Potable Water. New York, 1891.
Eoux. -Analyse Microbiologiqne des Eaux. Paris, 1891.
F. Fischer. Das Wasser. Berlin, 1891.
Leeds. Potable Water. Boston, 1891.
Crookes, Odling, and Tidy. Reports on London Water Supply.
A W. Bennett. Vegetable Gi'owths as evidence of the Purity or Impurity of
Water. Reprinted from St. Thomas's Hospital Reports, 1892.
Lankester. Evidence on Royal Commission on Metropolitan Water Supply, 1892.
Buchner. On River Water. Arch. /. Hygiene, 184, \892.
Schmidt. Ditto, ditto, xiii., 247, 1892.
V. & A. Babes. Filtration. Centr.f. BakterioL, xii., 132, 1892.
Koch. Wasserfiltration and Cholera. Zeit.f. Hyg., xiv., 393, 1893.
Koch. Cholera in I )eutschlaud. Ibid., xv., 89, 1893.
DuclatLx. On River Water. Ann. de Vlnst. Pasteur, Feb. 25, 1894.
Guinochet. iSpuration, Filtration, et Sterilisation des Eaux potables. Paris, 1894.
SEWAGE.
G. P. Brown. Sewer Gas. Chicago, 1881.
R. Warington. Nitrification and the Purification of Sewage by Soil. J. Soc.
Arts, April, 1882.
R. Warington. Same subject. British Association Meeting, 1884.
Stevenson. Sewage Disposal. Soc. of Med. Off. of Health, 1884-5.
Corfield and Parkes. Treatment and Utilisation of Sewage. London, 1887.
E. Frankland. Report on the Purification of Sewage in England. International
Congress of Hygiene, Vienna, 1887.
Massachusetts State Board of Health. Experimental Investigations on the
Purification of Sewage. Boston, 1888-90.
Lepsius. Frankfort Commission on Sewage, 1891.
Reports of Royal Commission on Metropolitan Sewage Discharge.
Rawlinson (Sir H.) London Sewage. J. Soc. Arts, xxxviii., 65.
Massachusetts State Board of Health. 24th Annual Report, 1893.
Santo Crimp. Sewage Disposal Works, 2nd edition, 1894.
Rafter and Baker. Sewage Disposal in the United States, 1894.
MISCELLANEOUS.
Vaughan. "Tyrotoxicon." Report Michigan State Board of Health. Chicago,
1886.
Squire. Companion to the British Pharmacopoeia with Supplement, 1890.
Dolan. Pasteur and Rabies. London, 1890.
■Williams. Antiseptic Dressings. Chemist and Druggist, 1892.
Burdett. Hospitals and Asylums of the World, vol. iv., 1893.
323
INDEX.
ABC process, 128.
Aberdeen process for preservation, 269.
Absynthol, 212.
Acetanilide, 185.
Acetate of aluminium, 132.
,, of copper, 115.
„ of lead, Basic, 134.
,, of zinc, 113.
Acetoarsenite of copper, 133.
Acid, Acetic, 225.
„ Anisic, 204.
• ,, Arsenic, 134.
„ Arsenious, 133.
„ Benzene sulphonic, 159.
,, Benzoboracic, 102.
,, Benzoic, 195.
,, Boric or Boracic, 99.
„ Carbolic, 149, 316.
,, Carbonic, 104.
„ Chromic, 132.
„ Cinnamic, 204.
„ Cresylic, 160.
„ Formic, 225.
,, Gallic, 205.
,, Hydrochloric, 69, 105.
,, Hydrocyanic, 105.
,, Hydronaphthoic, 180.
,, Naphthalene-sulphonic, 177.
,, Nitric, 87.
,, Oleic, 227.
,, Osmic, 144.
„ Phenyl-propionic, 205.
„ Picric, 181.
,, Pyrogallic, 172.
„ Pyroligneous, 173, 226.
,, Salicylic, 198, 314.
„ Sulpliobenzoic, 197.
„ Sulphuric, 97.
,, Sulphurous, 91, 234.
Acids, Vegetable, 227.
Air, Disinfeetion of, 245.
Alcohol, 223.
Alkalies, Salts of the, 106.
Allen's fluid, 168.
Altona, Sand filtration at, 14.
Aliiminium, 127.
,, acetate, 132.
,, chloride, 131.
,, sulphites, 132.
Alumnol, 179, 254.
Ambulances, 286.
Amido- benzene, 184.
Aminol, 184.
Ammonia, 109, 182.
Ammonium borate, 101.
,, carbonate, 109.
Amylamine, 184.
Analysis, Methods of, 301.
Andeer's lotion, 171.
Anderson's patent, 117.
,, process, 129.
Aniline, 184.
,, dye-s, 185.
Animal charcoal, 10.
Annidaline, 209.
Anthracene, 148.
Antipyrin, 188.
Antisepsin, 102.
,, Radlauer's, 112.
Antiseptic, Definition of, 2.
„ paper, 102, 140, 204, 255.
,, tablets, 204.
, , value. Determination of, 302.
Antiseptol, 194.
Antitoxine, 6.
Apyonin, 187.
Aristol, 209.
Arsenic, 13.3.
Arsenious solution, 308.
,, sulphide, 134.
Arsenite of potash, 133.
,, of soda, 133.
Asbestos, 13.
Aseptic, Definition of, 2.
Aseptol, 158.
Ashes and cinders, 13.
Ashpits, 231.
Australian salt, 102.
B
Baeillite, 162.
Bacteria, Methods of dealing with, 5.
Bacteriological methods of testing, 300.
Bakehouses, 243, 282.
Barlow's ventilator, 246.
Barmenite, 102.
Benzene, 148.
Benzoic aldehyde, 197.
Benzo-naphthol, 198.
„ -paracresol, 198.
Benzosol, 197.
Berlinite, 102.
Betol, 179, 199.
Bichromate of potash, 132.
324
INDEX.
Bird's process, 128.
Bismuth, 144.
,, subgallate, 144.
Black ash waste, 128.
Bleaching powder, 64.
Blue vitriol, 115.
Blyth's method of disinfection, 128.
Bond's pellets, 140.
Bone black, 10.
Borates, 100.
Tests for, 103, 309.
Borax, 100.
Bomeol, 212.
Boroglyceride, 101, 227.
Bradford's hot-air apparatus, 26.
Bread, 275.
,, Use of, for disinfecting walls, 292.
Brockmann's salt, 102.
Brom-acetanilide, 185.
Bromidine, 72.
Bromine, 70.
Bromo-camphor, 211.
Bromoform, 76.
Bromo-naphthalene night lights, 72.
Bromum solidifactum, 72.
Budenberg's flesh steriliser, 271.
Burnett's fluid, 110.
Butter, 274.
Bye-laws, Model, 290, 291.
Cadaverine, 97.
Calcium carbonate, 107.
„ hydrate, 107.
„ hypochlorite, 63.
,, sulphate, 107.
Calvert's powder, 154.
Camphoid, 213.
Camphor, 211.
Candles, Iodine, 73.
,, Sulphur, Kingzett's, 93.
,, ,, Seabury's, 93.
Carbide of iron, 117.
Carbolic powders, 154, 312.
,, soaps, 156.
Carbolised gauze, 155.
,, oil, 155.
,, solution, 155.
,, wool, 155.
Carbon, 10.
,, bisulphide, 98.
,, dioxide, 104.
Carbonate of ammonium, 109.
„ of lime, 107.
„ of soda, 108.
Carbostyrile, 193.
Carferal, 117.
Caryophyllin, 212.
Cats, 243.
Cattle markets, 243.
Cesspools, 240.
Chamberland filter, 14.
Charcoal, Animal, 10.
Charcoal, Vegetable, 11.
Cheese, 275.
Chemical methods of analysis, 307.
Chinese preservative powder, 102.
Chloralum, 131.
Chlorates, 69.
Chlorides, 70.
Chloride of aluminium, 131.
,, of copper, 114.
,, of lime, 63, 308.
„ of zinc, 109.
Chlorine, 57, 234.
Chloroform, 76, 219.
Chloronaphthalene, 180.
Chlorophenol, 157.
Chlorozone, 65.
Cholera, Prevention of, 280.
Chromium, 132.
Cisterns, 237.
Clark's method, 15.
Clay, 13.
Coal dust, 12.
Coke, 12.
Condensation in steam disinfectors, 27.
Candy's fluid, 310.
„ „ Red, 123.
„ ,, Green, 123.
,, powder, 126.
Conine, 190.
Copper, 113.
,, acetate, 115.
,, acetoarsenite, 133.
„ chloride, 114.
,, sulphate, 115.
Corrosive sublimate, 135.
Cowsheds, 243.
' ' Creo " disinfecting powder, 75.
Creolin, 166.
Creosol, 176.
Creosote, 161.
Cresol, 160.
Cresyl salicylate, 199.
Crimson salt, 125.
Culture and inoculation tests, 304.
"Cupralum," 116, 132.
Cyanogen, 142.
Dairies, 243.
Daudenant's patent. 111.
Deodorant, Definition of, 2.
Deodorisation, 7.
Desiccation, 16.
Destruction, 7.
Diamine, 183.
Diaptherin, 193.
Dimethylamine, 183.
Disinfectant, Definition of, 1.
Disinfectants, Bacteriological examin>
ation of, 300.
„ Chemical, 307.
Disinfecting, Primitive methods of, 2.
INDEX.
325
Disinfection, Definition of, 1.
„ by heat, 23.
,, by steam, 29.
„ Internal, 259.
,, in the middle ages, 3.
„ Personal, 252.
Rules for, 295-298.
Disinfectol, 156.
IMsinfector, Budenberg's, 51.
,, Equifex, 45.
,, Goddard's, 36.
„ house. Plan of, 52.
,, Manlove's, 38.
„ M'Lautlin's, 52.
„ plant for U.S. marine, 54.
„ Portable steam, 39.
„ Reek's, 47.
„ Schimmel's, 49.
• „ Thursfield's, 43.
„ Washington Lyon's, 34.
Downes and Blunt's experiments, 8.
Drains, 229.
Dressings, Antiseptic, 256.
Dust holes, 231.
Duclaux's experiments, 16.
Earth closets, 238.
Eau de Javelle, 63.
,, Labarraque, 63.
„ St. Luc, 111.
Eau Larnaudes, 112.
Epidemics, Prevention of, 279.
Equifex disinfectant sprayer, 235.
,, water steriliser, 248.
Essence of hops, 210.
Essential oils, 213.
Esset's fluid, 166.
Ether, Nitrous, 39.
Ethyl-amine, 184.
,, bromide, 78.
„ iodide, 78.
,, nitrite, 89.
Eucalyptol, 211.
Eucalypto-resorcin, 212.
Europhene, 78, 171-
Exclusion of infected persons, 5.
Fairs, 243.
Ferric chloride, 121.
,, sulphate, 120.
Ferro-manganese, 122,
Ferrous sulphate, 117.
Filter, Berkefeld's, 15.
„ Bischof's, 117.
,, Pasteur-Chamberland, 14, 248.
„ Stone, 15.
Filtration, Sand, 14.
Fluorides, 78.
Fluorine, 78.
Fluosilicates, 78.
Food, Preservation of, 262.
Formalin, 219, 272, 315.
Formic aldehyde or formalin, 219, 272.
Foreign systems, 291.
Fowler's solution, 133.
Furfurane, 187.
Furfurol, 187.
Furniture, 232.
Furs, 244.
Gannal's solution, 133.
Gargles, 255.
Gases, Influence of, on preservation, 104.
Gases and liquids. Purification of, 10.
Gases and vapours, 306.
Gauze, Carboliued, 155.
,, Iodoform, 77.
Sublimate, 140.
Germicidal value. Determination of, 303.
Gibbsite, 131.
Glacialin, 102.
Glycerine, 226.
Goddard's disinfecting chamber, 36.
Gold compounds, 144.
,, cyanide, 144.
Goulard's extract, 134.
Guaiacol, 175.
„ carboxylate, 176.
Gypsum, 13.
H
Haddan'S patent, 88.
Hager's test, 313.
Hair, 244.
Halogens, 57.
Hartmann's process, 271.
Heat as a disinfectant, 19.
" Hermite " process, 67.
Heydrich's salt, 102.
Hille's method of disinfection, 128.
Holden's process, 128.
Hospitals, Rules for, 286.
Hot air disinfection, 27.
Houses, 231.
Hydrazine, 183.
Hydrocarbons, 148.
Hydrogen peroxide, 84, 86, 309.
Hydronaphthol, 179.
Hydroxylamine, 183.
Hygienic wall papers, 231.
Hypochlorites, 63.
Hypodermic injections, 257.
I
IneinePatOP, Dr. Sergeant's, 53.
Indole, 192.
Infusorial earth, 13.
326
INDEX.
Infectious diseases, 279.
lodantipyrin, 189.
lodates, 75.
Iodine, 73.
„ candles, 73.
„ solution, 308.
,, trichloride, 74.
lodo-camphor, 211.
Iodoform, 76.
„ gauze, 77.
lodol, 78, 188.
lodophenol, 157.
Iron, 116.
,, carbide, 117.
,, perchloride, 121.
,, persulphate, 120.
,, sulphate, 117.
Izal, 169.
Jaeobsen'S mixture, 86.
Jeyes' automatic distributor, 241.
Johnson's patent, 86, 247.
Johnson and Saladin's patent, 96.
Jones' process for preservation, 267.
K
Keelin'S patent, 246.
Key's screen, 247.
Kieselguhr, 13.
Kingzett's patent, 247.
Kriiger's experiments, 129.
Laetacidine, 202.
Lano-creolin, 166.
Lawes' fluid, 171.
"Laurallene,"148.
Lavallee's fluid, 176.
Lead, 134.
,, acetate, Basic, 134.
,, nitrate, 134.
Leather's process, 247.
Leveson and Slater's process, 115.
Light, action on bacteria, 8.
Lime carbonate, 107.
,, slaked, 107.
,, sulphate, 107.
Listerine, 102, 197, 209.
Little's "soluble phenyle," 176.
Loretin, 193.
Lysol, 162.
M
Magdeburgr preservative salt, 102.
Magnetic carbide of iron, 117.
Magnetic spongy iron, 1 17.
Manganate of soda, 123.
Manganates, 123.
Manganese, 122.
,, peroxide, 122.
Manganous salts, 122.
Mayor's powder, 155.
M'Dougall's powder, 154.
Medical ofiicer of health, Duties of< 277.
Menthol, 209.
Mercuric albuminate, 141.
„ benzoate, 143.
,, carbolate, 143.
„ chloride, 135, 316.
,, chloro-amide, 143.
,, cyanide, 142.
„ imidosuccinate, 143.
,, iodide, 141.
„ naphtholacetate, 143.
,, naphtholate, 143.
,, nitrate, 135.
,, oxide, 135.
,, peptonate, 143.
,, salicylate, 143.
„ sulphocarbolate, 143.
,, tannate, 143.
,, thymolate, 143.
Mercurous nitrate, 135.
Metallic salts, 145.
Methane, 219.
Methyl alcohol, 219.
,, chloride, 219.
,, guaiacol, 176.
„ violet, 186.
Methylamine, 183.
Microcidine, 179.
Milk, 272.
,, Condensed, 273.
Mortuaries, 280.
Mouth M'ashes, 258.
Mur's patent, 247.
Myrtol, 212.
N
Naphthalene, 148, 177.
„ tablets, 148.
Naphthol, 177, 315.
,, salicylate, 179.
Naphtholeum, 180.
New Kiver Co. 's settling reservoirs, 16.
Nicotine, 189, 192.
Night-lights, Bromonaphthalene, 72.
,, Sussex patent, 73, 77.
Nitrate of lead, 134.
„ of mercury, 135.
,, of silver, 144.
,, of zinc. 111.
Nitric peroxide, 88.
Nitrites, 88.
Nitroantipyrin, 189.
Nitrobenzene, 89, 181.
Nitrocellulose, 182.
INDEX.
327
Nitrogen trioxide, 88.
Nitroglycerine, 182.
Nitrophenol, 181.
Nitro-toluene, 181.
Nitrous ether, 89.
Nunn's patent, 117.
Odamine, 171.
Oil, Carbolised, 155.
,, Carraway, 210.
,, Cinnamon, 210.
„ Cloves, 209.
,, Wintergreen, 199.
Ointments, 259.
Oxygen, 79.
Oxyquinoline, 193.
Ozone, 81.
Ozonisers, 81.
Pail system, 239.
Paper, Antiseptic, 102, 140, 204, 255.
Pasini's experiments, 9.
Payen's patent, 88.
Peat, 12.
,, charcoal, 12.
Perchloride of iron, 121.
,, of mercury, 135.
Periodates, 75.
Permanganate of potash, 124, 310.
Permanganates, 123.
Persulphate of iron, 120.
Petroleum, 148.
jelly, 227.
Phenol, 149, 310, 316, 234.
Phenolith, 155.
Phenosalyl, 200.
Picot's fluid, 176.
Piffard's patent, 266.
Pigeon and fowl houses, 243.
Pignol's fluid, 176.
Pinol, 218.
Piperidine, 189.
Piperine, 190.
Pixene, 163.
Pixol, 163.
Potassium arsenite, 133.
,, bichromate, 132.
„ borotartrate, 102.
„ dinitro-ortho-cresol, 182.
,, permanganate, 124.
Port sanitary authorities, 280.
Poudre de Come et Desneaux, 1.3.
Preservatives, Influence of, on digestion,
103.
Privies, 239.
Propylamine, 184.
Public Health Act, 277.
Pumice, 13.
Purvis's patent, 93.
Pyoctanin, 187.
Pyridine, 190.
Pyrocatechol, 173.
Pyrogallol, 172.
Pyrrol, 188.
Quarantine, 298.
Quicklime, 107.
Quinine, 194.
Quinoline, 192.
R
Rademann's patent, 156.
Radlauer's antisepsin, 112.
Rags, 244.
Raymond's disinfectant, 112.
Resol, 174.
Resopyrin, 189.
Resorcinol, 171.
Respirators, 259.
Retinol, 174.
Rotter ine, 113.
Roylat disinfector, 126.
Saeeharin, 197.
Salicylated gauze, 204.
Salicylate of zinc, 1 13.
Salipyrin, 189, 199.
Salbromanilide, 199.
Salol, 199.
Salophen, 199.
Salts of the alkalies, 106.
Salufer, 78.
Salzer's process, 269.
Sand filtration, 14.
Sanitary acts, 277-284.
,, carbon, 11.
,, inspectors, 277.
Sanitas, 86, 213.
Saprol, 167.
Sawdust, 13.
Sewers, 229.
Shale, 13.
Shilton's iodine solution, 73.
Sick rooms, 232.
Silver compounds, 144.
,, nitrate, 144.
Sinks, 232.
Skins, 244.
Slag, 13.
Slaughter houses, 243.
Smith's carbolated fluid, 166.
Soap, Antiseptic, 257.
„ Carbolic, 156, 314,
Society of medical officers of health.
Suggestions by, 289.
328
INDEX.
Soda, 108.
Sodium arsenite, 133.
,, carbonate, 108.
,, chloro-borosum, 102.
,, dithiosalicylate, 205.
,, manganate, 123.
„ parapheuol sulphonate, 158.
,, peroxide, 86.
,, sulphobenzoate, 197.
Soluble tartar, 102.
Soot, 12.
Sozal, 158.
Sozo-iodol, 78, 158.
,, mercury, 158.
Spencer's patent, 247.
Spiegeleisen, 122.
Stables, 243.
St. Bede disinfectant, 139.
Steam, Penetrating power of, 33.
Stothert's process, 1 28.
Streets, 241.
Strock's antiseptic paper, 204.
Styracol, 205.
Styrone, 205.
Sublimate gauze, 140.
Sulphate of copper, 1 15.
,, of iron, 117.
,, of lime, 107.
„ of zinc. 111.
Sulphates, 98.
Sulphide of arsenic, 134.
,, of carbon, 98.
Sulphite of aluminium, 132.
,, of zinc, 113.
Sulphites, 93.
Sulphocarbolate of zinc, 1 13.
Sulphur, 89.
,, candles, Kingzett's, 93.
,, ,.. Seabury's, 93.
,, dioxide, 91.
Sulphuretted hydrogen, 90.
Sulphurous acid, 91.
Tablets, Naphthalene, 148.
Talc, 13.
Tannin, 205.
Tar, 147, 311.
,, acids, 149.
,, oils, Neutral, 148.
,, Stockholm, 173.
Taylor's Eoylat disinfector, 126.
Terebene, 210.
Terpin hydrate, 212.
Terpinol, 212.
Thallene, 193.
Thiocamf, 94.
Thiophene, 148, 187.
Thymol, 208, 315.
Timber, Preservation of, 250.
Tin protochloride, 144.
Tobacco smoke, 191.
Toluene, 148.'
Tooth powders, 258.
Toxines, 6.
Tribromophenol, 157.
Tricresol, 164.
Trinitrophenol, 181.
Trimethylamine, 183.
Turpentine, 207.
Tuson's disinfectant, 112.
,, patent, 93.
Tweedie's powder, 155.
Tyndall's experiments, 21.
Tyrosine, 192.
Urinals, 242.
Vaccination, 262.
Vegetable charcoal, 11.
Vehicles, 244.
Verdigris, 115.
Victoria carbolic powder, 149..
w
Washing soda, 108.
Water, 247.
,, closets, 237.
Wheat, 275.
Wilson's disinfectant, 139.
Wimbledon process, 129.
Wintergreen oil, 199.
Wood creosote, 174.
„ paving, 242.
,, tar, 173.
„ work, 232.
Wool, 244.
,, Carbolised, 155.
,, Medicated, 316.
Zinc, 109.
,, acetate, 113.
„ chloride, 109.
„ mercury cyanide, 142.
,, nitrate. 111.
„ oxide, 109.
„ paraphenol sulphonate, 158.
,, salicylate, 113.
„ sulphate. 111.
,, sulphite, 113.
,, sulphocarbolate, 113, 158.
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