_PREVENTIVE MEASURES AGAINST INDUSTRIAL POISONING_
I
_GENERAL MEASURES_
In discussing preventive measures against industrial poisoning the
deductive method from the general to the particular will be followed. The
numerous instances of poisoning mentioned in Part I afford a practical
basis on which to formulate general rules before passing on to describe
special measures. Technical details will be omitted, as they must be left
to the technical expert whose business it is to draw up the plans as a
whole and to modify them according to the requirements of individual
cases.
In the effort to control industrial poisoning and disease it is necessary
to insist absolutely on the concerted action of all concerned. In this
co-operation every one is called who through his knowledge and sphere of
activity is in a position to assist.
The medical man comes in with his special knowledge of the action of
poisons as toxicologist, as practising physician (especially as works
surgeon and doctor of the sick insurance society), and also in an
official capacity as appointed surgeon or medical officer of health; the
technical expert comes in as engineer, as manager, as foreman, and as
factory inspector. But above all the interest and active co-operation of
employers and employed are needed as well as the organisations of both.
That the workers should understand and co-operate is essential for the
success of preventive measures, and subsequently it will be shown in what
direction this co-operation is most necessary.
To make possible such co-operation interest must be aroused and
suitable information and teaching supplied to the parties concerned.
Medical men and practical workers require to receive instruction in
industrial hygiene, and teaching on this subject should be arranged
for in secondary and technical schools. Medical men and others who, as
officials and insurance doctors, are brought constantly into touch with
industrial workers should have opportunity—by means of special courses
and lectures—to keep pace with advancing knowledge in this direction.
Beside these there are, as educative organisations, special Institutes
of Industrial Hygiene and special hospitals for treatment of diseases
of occupation which bring together the patients and the teaching staff
and so facilitate pursuit of knowledge and research. A beginning of
this kind has already been made by the Industrial Hygiene Institute,
Frankfurt a.-Main, and the hospital for diseases of occupation at Milan,
showing that the ideas are attainable. International agencies which unite
all circles interested in the subject irrespective of profession or
nationality in common interchange of thought and discussion are of great
significance for uniform development of needful preventive measures;
international congresses, often in connection with exhibitions, have
given valuable stimulus and have been the starting-point of permanent
international societies, unions, and organisations. The significance
for our inquiry of these international efforts will be more closely
considered in the following pages.
II
_GENERAL CONSIDERATIONS ON SOCIAL AND LEGISLATIVE MEASURES_
INTERNATIONAL PREVENTIVE MEASURES, NOTIFICATION OF INDUSTRIAL POISONING,
LISTS AND SCHEDULES OF INDUSTRIAL POISONS
Experience and inquiry in the field of industrial poisoning led to a
series of demands which, supported as they were by a general movement
for the protection of workers, were soon followed by regulations and
legislative action. For a long time efforts have been directed to treat
industrial disease and poisoning in the same way as has been done in
the case of industrial accidents. The question, however, is attended
with much greater difficulty. On the other hand, uniform international
regulation of questions affecting prevention of disease is called for
both on humanitarian and economic grounds.
The idea of international legislation for the protection of workers
was first mooted about the year 1870. The possibility and need of such
intervention was much discussed and interest in it kept constantly alive,
especially in Switzerland, until the organisations of the workers took
up the idea. Several attempts failed. In France in 1883 a proposal of
the Socialist party aiming at international agreement on the subject
of protection of the workers was rejected. In 1885 (in opposition
to Hertling) Prince Bismarck expressed himself strongly against the
possibility of such international protection. But the stone, once set
rolling, could not be stayed. In the years 1886, 1887, and 1888 the
French and English trade unions, as well as the Swiss Federal Council,
took up the question afresh. These endeavours at last took tangible shape
in the first International Conference for the protection of workers held
in Berlin in March 1890. This date remains a landmark in the history of
the subject, but not until ten years later—1900—did the Congress held
in Paris for the international legal protection of workers lead to the
establishment of what had been repeatedly urged, namely, creation of an
International Bureau. This was inaugurated at Basle in 1901 and forms the
headquarters of the National Associations for Labour Legislation called
into being in various countries.
This International Association meets regularly in conference, as in
Cologne (1902), Berne (1905), Lucerne (1908), Lugano (1910), and Zurich
(1912). The questions raised in the International Labour Bureau,
which receives financial aid from a number of States, are fully and
scientifically discussed with the object of finding a basis on which to
bring into agreement the divergent laws of the different countries. A
further task of this strictly scientific institution is the collection
and publication of literature bearing on the protection of workers in
one and another country, distribution of information, and the editing of
reports and memoranda. The question of prevention of industrial poisoning
has always taken a foremost place in the programme of the International
Association and in the agenda of the International Labour Bureau. At its
first meeting a resolution was adopted advocating the prohibition of the
use of white phosphorus and white lead, and the Labour Bureau in Basle
was instructed to take the necessary steps. Special, if not prohibitive,
economical considerations foreshadowed difficulties—all the greater
because the matter at issue concerned prohibition of articles playing
a part in the markets of the world. Just on that account international
treatment of such questions is necessary, since a peaceful and orderly
solution can only be arrived at on such lines. International effort
endeavours here to press with equal weight on the countries competing
with one another commercially, so that in the protection of the workers
economic adjustment is sought in order that efforts based on humanitarian
grounds shall not at the same time cause economic disadvantages, the aim
being to produce general welfare and not merely protection of one class
at the expense of another.
Through these international agreements between various countries success
in the direction aimed at is hopeful, and indeed to a certain extent—as
in the phosphorus and lead questions—actually attained. Thus, for
example, Germany and Italy were in a position to enforce prohibition of
the use of white phosphorus early, while their neighbour Austria, on
account of commercial and political considerations and the conditions of
the home lucifer match industry, has only recently decided on prohibition.
As international agreement for the protection of workers is advisable
on economic grounds, so also is it reasonable and just from purely
humanitarian reasons that workers, without reference to civil condition
or nationality, should be equally protected. On this point it is proposed
to take a vote and to press only for those reforms which are thoroughly
sound and recognised as necessary.
The first step in such a comprehensive attack is precise knowledge of
the extent and source of origin of the particular forms of industrial
poisoning and disease and the collection of reliable statistics. This
suggested the obligation to notify such cases to the proper authorities
in the same way as is now done in the case of infectious disease. A
motion to this effect had already been passed at the Conference of the
International Association for Labour Legislation held in Basle, and a
request was made to the Labour Bureau to prepare a list of the diseases
and poisonings in question. To them we shall refer later, but a schedule
is necessary as a basis to work upon. Yet even when this is done there
are obviously great difficulties to be overcome in carrying out the
requirement of notification when the aim is kept in mind of collecting
complete statistical data for controlling the conditions giving rise
to industrial disease. The proposal of the International Association
seeks to make notification obligatory on the part both of the medical
practitioner in attendance and the occupier, and in connection with
this to secure the co-operation of the Sick Insurance Society.[D] The
proposal to require the appointed surgeons and surgeons of the Insurance
Society to notify all cases is hardly feasible in view of their dependent
position. Nor can the obligation on the occupiers lead to the desired
result because of their lack of medical knowledge and the fact that
by notifying they might be forced to act to their own disadvantage. A
successful effort in this direction is recorded in Saxony, where lead
poisoning was first made a notifiable disease, and later the general duty
of notification of industrial poisoning was prescribed by Order dated
March 4, 1901.
+-----------------------+-----------------------------------------------+
| | Reported Cases.[E] |
| Disease and Industry. +-------+-------+-------+-------+-------+-------+
| | 1912. | 1911. | 1910. | 1909. | 1908. | 1907. |
| (1) | (2) | (3) | (4) | (5) | (6) | (7) |
+-----------------------+-------+-------+-------+-------+-------+-------+
|Lead Poisoning |587 (44|669 (37|505 (38|553 (30|646 (32|578 (26|
| 1. Smelting of metals| 56 (7| 48 (3| 34 (5| 66 (5| 70 (2| 28 (2|
| 2. Brass works | 5 | 9 (1| 7 | 5 | 6 | 9 (1|
| 3. Sheet lead and | | | | | | |
| lead piping | 6 | 12 | 4 | 9 (2| 14 | 6 |
| 4. Plumbing and | | | | | | |
| soldering | 35 (5| 37 (2| 25 (1| 28 | 27 | 20 (2|
| 5. Printing | 37 | 32 (2| 33 (4| 21 (1| 30 (2| 26 (3|
| 6. File cutting | 13 | 18 (2| 9 (1| 8 | 9 (2| 10 |
| 7. Tinning | 15 (11| 13 | 17 | 22 | 10 | 25 |
| 8. White lead | 23 | 41 (2| 34 (1| 32 (2| 79 (3| 71 |
| 9. Red lead | 3 | 13 (1| 10 | 10 | 12 | 7 |
| 10. China and | | | | | | |
| earthenware | 80 (14| 92 (6| 77 (11| 58 (5|117 (12|103 (9|
|10a. Litho-transfers | 1 (1| 1 | 1 | 1 | 2 | 10 |
| 11. Glass cutting and | | | | | | |
| polishing | 1 (1| 5 | — | 4 (2| 3 (1| 4 |
| 12. Vitreous | | | | | | |
| Enamelling | 5 | 19 (1| 17 | 7 | 7 | 6 |
| 13. Electric | | | | | | |
| accumulators | 38 (1| 24 (1| 31 | 27 (2| 25 (1| 21 |
| 14. Paints and colours| 19 | 21 | 17 (1| 39 (2| 25 | 35 (1|
| 15. Coach building | 84 (7|104 (5| 70 (6| 95 (6| 70 (3| 70 (3|
| 16. Ship building | 34 (2| 36 (6| 21 (2| 27 (1| 15 | 22 (1|
| 17. Paint used in | | | | | | |
| other industries| 48 (3| 56 (1| 51 (3| 42 | 47 (1| 49 (2|
| 18. Other industries | 84 (2| 88 (4| 47 (3| 52 (2| 78 (5| 56 (2|
| | | | | | | |
|Phosphorus Poisoning | — | — | — | 3 | 1 | 1 (1|
| | | | | | | |
|Arsenic Poisoning | 5 | 10 (1| 7 | 4 | 23 (1| 9 (2|
| | | | | | | |
|Mercurial Poisoning | 17 | 12 | 10 (1| 9 | 10 | 7 |
| | | | | | | |
|Anthrax | 47 | 64 (11| 51 (9| 56 (12| 47 (7| 58 (11|
| Wool | 31 (6| 35 (10| 28 (3| 28 (3| 18 (3| 23 (3|
| Horsehair | 7 | 8 (1| 6 (1| 8 (2| 10 | 17 (4|
| Handling of hides and | | | | | | |
| skins | 8 | 20 | 14 (3| 18 (6| 13 (1| 12 (2|
| Other industries | 1 | 1 | 3 (2| 2 (1| 6 (3| 6 (2|
+-----------------------+-------+-------+-------+-------+-------+-------+
+--------------+-------+-------+-------+-------+-------+-------+--------+
| | 1906. | 1905. | 1904. | 1903. | 1902. | 1901. | 1900. |
| | (8) | (9) | (10) | (11) | (12) | (13) | (14) |
+--------------+-------+-------+-------+-------+-------+-------+--------+
|Lead |632 (33|592 (23|597 (26|614 (19|629 (14|863 (34|1058 (38|
| 1. | 38 (1| 24 (1| 33 (1| 37 (2| 28 | 54 (3| 34 (1|
| 2. | 11 | 5 (1| 10 (1| 15 | 5 | 6 (1| 3 |
| 3. | 7 | 9 | 7 | 11 | 12 | 17 | 17 (1|
| 4. | 16 (4| 24 (2| 21 (3| 26 | 23 (1| 23 | 9 |
| 5. | 16 (2| 19 (4| 15 | 13 (2| 19 | 23 (1| 18 (2|
| 6. | 15 | 12 | 20 (4| 24 (2| 27 (1| 46 (7| 40 (3|
| 7. | 18 (1| 14 (1| 10 | 14 | 11 | 10 | 5 |
| 8. |108 (7| 90 |116 (2|109 (2|143 (1|189 (7| 358 (6|
| 9. | 6 | 10 | 11 | 6 | 13 | 14 | 19 |
| 10. |107 (4| 84 (3|106 (4| 97 (3| 87 (4|106 (5| 200 (3|
| 10a. | 5 | 5 | 3 | 3 | 2 | 7 | 10 |
| 11. | 4 (1| 3 | — | 4 | 8 (2| 11 (3| 7 |
| 12. | 4 | 2 | 3 | 4 | 3 (1| 9 | 11 |
| 13. | 26 | 27 (1| 33 | 28 | 16 (1| 49 (1| 33 |
| 14. | 37 | 57 (1| 32 (1| 39 (1| 46 | 56 | 56 (1|
| 15. | 85 (7| 56 (3| 49 (4| 74 (5| 63 (1| 65 (4| 70 (5|
| 16. | 26 (1| 32 (2| 48 | 24 (1| 15 (1| 28 (1| 32 (2|
| 17. | 37 (3| 49 (2| 27 (3| 46 (1| 44 (1| 61 | 50 (5|
| 18. | 66 (2| 70 (1| 53 (3| 40 | 64 | 89 (1| 86 (4|
| | | | | | | | |
|Phosphorus | — | 3 (1| 1 (1| — | 1 (2| 4 | 3 |
| | | | | | | | |
|Arsenic | 5 | 1 | 5 | 5 | 5 | 12 (1| 22 (3|
| | | | | | | | |
|Mercurial | 4 | 8 | 3 | 8 | 8 | 18 | 9 |
| | | | | | | | |
|Anthrax | 67 (22| 59 (18| 50 (10| 47 (12| 38 (9| 39 (10| 37 (7|
| Wool | 24 (8| 34 (12| 12 (1| 20 (5| 12 (2| 6 (4| 9 (2|
| Horsehair | 10 (4| 7 (1| 12 (4| 7 (1| 10 (2| 9 (1| 12 (3|
| Hides | 19 (7| 17 (4| 18 (3| 12 (1| 11 (5| 20 (5| 9 (1|
| Other | 14 (3| 1 (1| 8 (2| 8 (5| 5 | 4 | 7 (1|
+--------------+-------+-------+-------+-------+-------+-------+--------+
My own experience does not lead me to expect much in elucidation of
industrial diseases from the Sick Insurance Societies. In Austria they
make a statistical return as to the causation of illness to the central
authorities. I have myself—in my capacity as an official of the State
Central Board—examined these in order to try and gain knowledge of
the extent of industrial disease in Bohemia. In spite of the returns
drawn up by the district surgeon who visits the factories in question,
it was impossible for me to obtain a complete picture of the extent
of industrial sickness. The reports only give valuable data on which
to base action in particular cases, and from this standpoint I do not
under-estimate their value. But so far as the expressed wish of the
International Association is concerned they appear to fulfil it, inasmuch
as for specially dangerous trades special reports are issued, the
Austrian law for sick insurance requiring such industries to institute
separate sick insurance funds with separate statistics. Hence, under
present conditions, I do not see how the duty of notification will be
effective. There remains the endeavour to secure insurance and the
right to claim compensation for industrial disease in the same way as
is provided for accidents. This point was fully discussed at the eighth
International Congress for Workmen’s Insurance held in Rome in 1908.
There is no valid ground for granting compensation only for _sudden_
disturbance of health arising in the course of employment by accident or
acute poisoning, and withholding it in the case of _gradual_ disturbance
of health caused equally by the trade, as the effects of such chronic
indisposition weigh often no less heavily on the sufferer. Inclusion
of industrial disease in the same category as accident insurance, as
indeed has been done in France, Switzerland and Great Britain, has,
apart from the fact that it is dictated by fairness and humanity, the
advantage of removing existing hardship and of solving doubtful cases.
Correct statistics, further, would thus be obtainable for the first
time, and the employer by insurance would be freed from the legal
proceedings now frequently brought against him for injury due to chronic
industrial poisoning. And it seems the more right and just course to
institute a general scheme of insurance against industrial disease than
to have recourse to an Employer’s Liability Act in this or that case,
particularly as the question often arises in regard to a disease which
develops gradually—In whose employment was the disease contracted?
Clearly in such a scheme of insurance against both accident and
industrial disease only specific industrial diseases would be included,
i.e. diseases in which the connection with the industry can be clearly
established as due to causes inherent in the industry, and traceable to
definite materials used. Such diseases as tuberculosis and the effects
of dust inhalation (bronchitis, &c.), which as industrial diseases occur
only too often, cannot be called specific, because they arise outside
the industry and make decision impossible as to whether or not in a
particular case the disease owed its origin to the occupation. In order
to determine what should be regarded as specific industrial poisons it
was deemed necessary to draw up a schedule. For one such list Sommerfeld
(in collaboration with Oliver and Putzeys) is responsible, Carozzi of
Milan for a second, and Fischer[F] for a third, published in 1910. Those
by Sommerfeld and Fischer are constructed in similar fashion—enumeration
of (1) the poisonous substance, (2) the industries in which it is made
or used, (3) the channel of absorption, and (4) the symptoms produced.
Sommerfeld enumerates the poisons in alphabetical order, noting against
each the requisite preventive measures, while Fischer adopts a chemical
classification, confining himself to general introductory remarks as to
prevention.
Sommerfeld proposes to limit notification to poisoning sharply
defined as to the symptoms set up, such as lead, phosphorus, mercury,
arsenic, chromium, carbonic oxide, aniline, benzene, nitrobenzene,
carbon bisulphide, and nitrous fumes. This simplifies the obligation
to notify, but does not dissipate the fears expressed above as to the
difficulty, because in the present development of the chemical industries
new substances involving new danger to the persons handling them are
constantly being discovered, and thus there can be no finality as to
which industrial poisonings should entitle to compensation. And if
recourse were had from time to time to additions of new substances to
the schedule, reliance would have to be placed on experience with regard
to each substance added, and thus the actual individual who had suffered
would not benefit. Fischer, indeed, acknowledges that any schedule must
be incomplete, and emphasises the fact that continual additions would
be necessary; otherwise it would be better to refrain altogether from
publication of a list. Such lists may be valuable guides, but no sure
foundation for insurance legislation. The only possible way to do this
is to give as far as possible a correct definition of the industrial
diseases entitling to compensation and, in isolated cases, to leave the
decision to the expert opinion of competent judges.
Extension of workmen’s insurance to cover chronic industrial poisoning
is, however, most desirable in the interest of employers and employed,
and also of science. The German accident insurance legislation is
especially suited to do this, since the trade organisations direct their
attention not only to the prevention of accidents but of industrial
diseases also.
III
_SPECIAL PREVENTIVE MEASURES FOR WORKERS_
SELECTION, CHOICE OF TRADE, ALTERNATION OF EMPLOYMENT, MEDICAL CONTROL,
SAFETY APPLIANCES, INSTRUCTION AND CO-OPERATION OF WORKERS, CLOTHING,
ATTENTION TO CLEANLINESS, FOOD, GENERAL WELFARE
As a practical measure in protection against trade risk selection of
those capable of resisting danger has to be considered. It is obviously
desirable to select for employment in a dangerous trade persons
possessing powers of resistance, because predisposition and resistance
to the action of poisons differ markedly in individuals. To some extent
such a selection comes of itself, as those who are very susceptible
are obliged by repeated attacks to give up the work. The social and
physical misery, undeserved loss of employment, illness, and perhaps
early death following on this kind of selection might be checked by
timely medical examination so as to weed out the unfit. But medical
examination prior to admission into a dangerous trade (actually practised
in many industries involving risk of poisoning) inflicts hardship on
those seeking employment, and recruits the ranks of the unwillingly
unemployed. It would be much better were it possible to meet the need
of selection by pertinent direction and guidance in choice of calling.
There should be insistence in technical schools especially on the
dangers inherent in certain industries, school medical examination as to
physical qualifications for certain industries, and careful note made of
individual suitability in labour bureaus, apprentice agencies, and the
like.
Young female workers, naturally less able to resist, should be excluded
from work involving risk of poisoning—a principle which has been acted on
in the legislation of civilised countries.
Further, workers engaged in industries involving risk should not be
exposed to the pernicious influence for too long a time. Hence the
hours of employment should be shortened in occupations proved to be
injurious to health. An important aid in this respect is alternation of
employment. Change of occupation is particularly recommended where the
nature of the poisoning of which there is risk is cumulative in action,
because in the intervals from the work the system will rid itself of the
accumulated store. In this way a number of skilled resistant workers,
familiar with the risk and knowing how to meet it, will be maintained.
Casual labour works in a vicious circle—increase of fresh workers
increases the danger and the number of cases of poisoning, and, _vice
versa_, these augment again the need of change in the personnel, so that
the number of cases of poisoning rises very high. Thus the industry
itself may be endangered, since its prosperity depends mainly upon the
existence of a skilled staff of workers. In dangerous trades, therefore,
Hermann Weber’s words, ‘Change of work instead of change of workers,’
have much force.
Periodical medical examination in these industries cannot well be omitted
in order to weed out the physically unfit, and to suspend from work those
who show early symptoms. Note should be kept of the state of health of
the workers, the results of the periodical medical examination, the
duration of symptoms, and the treatment of any illness that occurs.
Medical supervision presupposes special training and experience in the
medical man entrusted with the task.
Further, in some industries in which poisonous materials are used,
especially such as set up acute sudden poisoning, there should be a
trained staff competent to recognise the first symptoms of poisoning and
to render first aid, and having at its disposal adequate means of rescue.
Apart from the rescue appliances generally needed in dangerous trades,
stress must be laid on the value of oxygen apparatus as a means of
saving life. In addition to what is needed for the sufferer there must
be defensive apparatus at hand for the rescuers (breathing helmets,
&c.), to facilitate and make safe their rescue work when in a poisonous
atmosphere. Without such defensive equipment rescuers should never
venture into gas conduits, or into any place where presumably a poisonous
atmosphere is to be met with. It hardly requires to be said that in
dangerous industries medical aid should be within easy reach; in large
works actual medical attendance may be necessary.
In acute as well as in chronic cases of poisoning early medical
intervention is advisable. Hence medical aid should be sought on the
earliest appearance of symptoms, and the worker, therefore, should
know the nature and action of the poison with which he comes into
contact. This brings us to the subject of the education of the worker
and particularly observance of all those rules and regulations in which
his co-operation is necessary. This co-operation of the workers is
indispensable; it is the most important condition of effective defence.
The best regulations and preventive measures are worthless if the worker
does not observe them. He must be taught their aim, the way of using the
means of defence; he must be admonished to use them, and, if necessary,
compelled to do so. The co-operation of workmen’s organisations in this
matter can avail much, since a workman most readily follows the advice of
a fellow-worker.
Teaching of the kind suggested can be done in different ways. Apart from
lectures and practical courses, concise instructions, either in the
form of notices or as illustrated placards, should be posted up in the
workrooms or handed in the form of leaflets particularly to the newly
employed. Distribution of such leaflets might well be placed as a duty on
the employer.
Of preventive measures applying to the individual those are of prime
importance which serve to protect the worker, as far as is practicable,
from coming into contact with the poison. Protection of this kind is
attained by wearing suitable clothing, use of respirators, and careful
cleanliness—especially before partaking of food. It cannot be too
strongly urged that these precautions are a very potent defence against
the danger of industrial poisoning, especially of the chronic forms,
and in teaching workers their importance must be insisted on. It is not
sufficient merely to put on overalls over the ordinary clothes. The
ordinary clothes must be taken off before the commencement of work, and
working suits put on, to be taken off again before the principal midday
meal and before leaving work. They should be made of smooth, durable,
washable material, and be properly washed and dried not less often than
once a week. They must be plainly cut without folds or pockets.
Direct handling of the poisonous substances is to be avoided, but where
this is necessary impervious gloves may have to be worn, especially in
the case of poisons which can be absorbed through, or act injuriously on,
the skin. If there is risk of splashing or spilling of poisonous liquids
on to the clothes, impermeable or partly impermeable overalls (aprons,
&c.) should be worn. The obligation of providing the overalls or working
suits falls naturally on the employer in industries where poisonous
substances are used, and there is equally obligation on the employee to
use the articles provided.
Suitable cloakroom accommodation is essential, by which is meant room not
only to change clothes with cupboards or hooks on one side for clothing
taken off on commencement of work and on the other the working suits,
but also ample washing accommodation. These cupboards should be double,
that is, be divided by a partition into two parts, one serving for the
ordinary and the other for the working clothes.
[Illustration: FIG. 35.—Aluminium Respirator]
Protection of the respiratory organs can to some extent be obtained by
so-called respirators worn over the mouth and nose. Often they consist
simply of a moist sponge or folds of cloth, or again may be complicated
air-proof affairs enclosing mouth and nose, or the whole face like a
mask, or even the head like a helmet; they fit close, and the aperture
for respired air is provided with filtering material (cotton wool, &c.)
placed between two layers of wire gauze. The outer layer of the gauze
moves on a hinge, so that the filtering material can be renewed after
each time that it has been used. The construction of respirators is
extraordinarily varied. One form is illustrated. They must be light, and
in order not to obstruct breathing seriously they are often provided
with valves—closing during inspiration and opening during exhalation.
Generally the respirators in common use do not quite satisfactorily
fulfil the conditions required. After a time the pressure becomes
irksome, the face becomes hot, breathing more difficult, and discomfort
from wearing them unbearable.
Respirators are only to be regarded in the light of secondary aids and
for occasional use.
During temporary exposure to an atmosphere charged with poisonous dust
the wearing of an efficient apparatus—preferably one protecting the
head—is very desirable.
[Illustration: FIG. 36.—Smoke Helmet, Flexible Tubing, and Foot Bellows
(_Siebe, Gorman & Co._)]
Respirators afford no protection, or a very imperfect one, against
dangerous gases or fumes. If soaked with an absorbing or neutralising
fluid they can scarcely be worn for any length of time.
In an atmosphere charged with poisonous gas recourse should be had either
to a smoke helmet with flexible tubing and bellows or to an oxygen
breathing apparatus so constructed that the workman carries the necessary
supply of oxygen with him in a knapsack on his back. In the latter case
oxygen from a compressed cylinder of the gas is conveyed to the breathing
mask, so that respiration is independent of the surrounding atmosphere.
[Illustration: FIG. 37.—Diagram of Draeger 1910-11, Pattern H (_R.
Jacobson_)
P Alkali cartridges; K Cooler; C Aspirating pipe; L₁ Purified air; L₂
Expired air.]
The mode of working is represented diagrammatically in figs. 37 and 40.
After putting on the helmet, the bag is first filled with fresh air, the
air valve is then closed, and the valve of the oxygen cylinder unscrewed
so as to permit of the flow of the oxygen which, mixes with the air in
the bag, and begins to circulate; the expired air passes through the
caustic potash pellets P, which free it of carbonic acid gas, so that,
with a fresh supply of oxygen from the cylinder through the pipe C, it
is regenerated and made fit for breathing again. The pressure in the
cylinder is measured by a manometer, which indicates also when the supply
of oxygen gives out.
[Illustration: FIG. 38.—Showing the Potash Cartridge No. 2 with Change
Mechanism X; No. 2 Oxygen Cylinder with Spanner V; and on the Left a
Hexagonal Socket U, for unscrewing the Locking Nuts of Reserve Cylinders
(_R. Jacobson_)]
[Illustration: FIG. 39.—‘Proto’ patent self-contained breathing apparatus
(_Siebe, Gorman & Co._)]
Another apparatus—the ‘Proto’ patent self-contained breathing
apparatus (Fleuss-Davis patents)—is also illustrated in fig.
39. Illustration 40 gives a diagrammatic view of the principle
upon which it is designed. The instructions for using the
‘Proto’ apparatus are as follows:
_The oxygen cylinders_ (B, B), having been charged with oxygen
through the nipple at (H) to a pressure of 120 atmospheres
(about 1800 lbs. per square inch), are to be re-attached to
the belt as shown, and the reducing valve, with its tubes,
&c., is to be connected to the nipple at (H). This supply is
sufficient for fully two hours.
_Charging the breathing bag._—Put 4 lbs. of stick caustic
_soda_ into the bag (D), i.e. 2 lbs. into each compartment,
and immediately fasten the mouth of the bag by means of the
clamps and wing nuts (O). If the apparatus is not to be used
at once, but is to be hung up for use at some future time, the
indiarubber plug which is supplied with the apparatus should be
tightly fitted into the mouthpiece in order to prevent access
of air to the caustic soda, and to preserve it until required
for use.
See that the inlet and outlet valves (T and S) and the
connection (N) are screwed up tightly.
The small relief valve (K) is only to be opened (by pressing
it with the finger) when the bag becomes unduly inflated
through excess of oxygen. This may occur from time to time,
as the reducing valve is set to deliver more than the wearer
actually requires.
_Equipment._—The whole apparatus is supported upon a broad belt
which is strapped round the body. The bag is also hung by a
pair of shoulder braces.
The wearer having put the equipment over his shoulders, fastens
the belt and takes the plug out of the mouthpiece. The moment
the mouthpiece is put into the mouth or the mask is adjusted,
the main valve (H) is to be opened not more than one turn and
the necessary supply of oxygen will then flow into the bag. It
is advisable to open the by-pass (I) to inflate partially the
breathing bag (D) for a start, but this valve should again be
screwed up quite tight and not touched again, except in the
case of emergency as previously described should the bag become
deflated. Breathing will then go on comfortably.
Should the by-pass (I) on the reducing valve (C) get out of
order then the wearer should turn on the by-pass (I) from time
to time to give himself the necessary quantity of oxygen, but,
as stated above, this is only to be done in case of deflation
of the bag. The best guide as to the quantity of oxygen to
admit _in the above circumstances_ is the degree of inflation
of the breathing bag. It will be found to be quite satisfactory
if the bag be kept moderately distended.
_After using the apparatus._—The caustic soda should _at once_
be thrown away, but if it is neglected and the soda becomes
caked, it must be dissolved out with warm water before putting
in a fresh supply. Caustic soda will not damage vulcanised
indiarubber, but it will damage canvas and leather, and will
burn the skin if allowed to remain upon it.
If the apparatus is to be used again at once, it can be
recharged with caustic soda at once, but if it is only to be
charged ready for use at some future time the indiarubber bag
should be thoroughly washed out with warm water and dried
inside with a cloth or towel.
When emptying or recharging the rubber bag with caustic soda,
it must always be removed from the canvas bag. After use each
day, it is advisable to wash the rubber mouthpiece (or mask,
as the case may be) with yellow soap and water. This acts as a
preservative to the indiarubber.
Every man who is to use the apparatus should have his own
mouthpiece and noseclip, or mask, as the case may be, under
his own special care, both for sanitary reasons and so that he
may shape and adjust the mask to fit himself comfortably and
air-tightly, to such an extent that if the outlets are stopped
up by the hands while the mask is held in position by its bands
no breath can pass in or out.
[Illustration: FIG. 40.—‘Proto’ Patent Self-breathing Apparatus (_Siebe,
Gorman & Co._)]
[Illustration: FIG. 41.—Arrangement of Cloak-room, Washing and Bath
Accommodation, and Meal-room in a White Lead Factory]
Where poisonous substances giving off dust or fumes are used, regular
washing and rinsing the mouth (especially before meals and on leaving)
is of great importance. Naturally the washing conveniences (basins,
soap, brushes, towels) must be sufficient and suitable, and the workers
instructed as to the importance of cleanliness by the foreman. They
should be urged to bath in rotation, and time for it should be allowed
during working hours.
The taking of meals and use of tobacco in the workrooms must be
prohibited. Meal rooms should be so arranged as to be contiguous to the
cloakroom and washing accommodation, the worker gaining access to the
meal room through the cloakroom and bathroom. The arrangement described
is illustrated in fig. 41. The meal room serves also the purpose of a
sitting-room during intervals of work, and it goes without saying that
cloakroom and lavatory accommodation are as necessary in small as in
large premises.
Simple lavatory basins of smooth impervious surface fitted with a waste
pipe and plug, or tipping basins, are recommended in preference to
troughs which can be used by several persons at once. Troughs, however,
without a plug, and with jets of warm water, are free from objection.
The douche bath has many advantages for workmen over the slipper bath.
The initial cost is comparatively small, so that it can be placed at the
disposal of the workers at very small outlay. Maintenance and cleanliness
of douche baths are more easily secured than of other kinds, where
changing the water and keeping the bath in good order involve time and
expense. A dressing-room should form part of the douche or slipper bath
equipment. Walls and floors must be impervious and, preferably, lined
with smooth tiles or cement. It is better that the shower bath should be
under the control of the worker by a chain rather than be set in motion
by means of mechanism when trodden upon. The arrangement of baths is
illustrated in fig. 43. In many large works large bath buildings have
been erected. Fig. 44 is a plan of the splendid bath arrangements at the
colour works of Messrs. Lucius, Meister & Brüning of Höchst a.-M.
[Illustration: FIG. 42.—Good Washing and Bath Accommodation in a Lead
Smelting Works]
[Illustration: FIG. 43.—Washing Trough, Douche Baths, and Clothes
Cupboards, Type common on the Continent]
[Illustration: FIG. 44A.—Baths in the Höchst Aniline Works (_after
Grandhomme_)]
[Illustration: FIG. 44B.—Ground Floor]
[Illustration: FIG. 44C.—First Floor. _a_, _c_, Baths (slipper and
douche) for workmen; _b_, Washing accommodation for workmen; _d_, _e_,
Baths for officials; _g_, Attendant’s quarters; _f_, Hot air (Turkish)
baths; _i_, Warm water reservoir.]
Naturally maintenance of the general health by good nourishing diet is
one of the best means of defence against onset of chronic industrial
poisoning. Over and over again it has been noticed that ill-fed workers
speedily succumb to doses of poison which well-nourished workers can
resist. It is not our province here to discuss fully the diet of a
working-class population. We merely state that it is a matter of vital
importance to those employed in dangerous trades. The question of a
suitable drink for workers to take the place of alcohol calls for special
attention, as, when complicated with alcoholism, both acute and chronic
poisonings entail more serious results than they otherwise would do.
Over-indulgence in alcohol, owing to its effect on the kidneys, liver,
digestion, nervous system, and power of assimilation generally, requires
to be checked in every way possible. Apart from good drinking water,
milk, coffee, tea, fruit juices and the like, are excellent. Milk is
especially recommended, and should be supplied gratis to workers in
dangerous trades, notably where there is risk of lead poisoning.
Lastly, other features such as games and exercise in the open air,
which help to strengthen bodily health, must not be forgotten. In this
connection much good work has already been done by employers’ and
workers’ organisations.
IV
_GENERAL REMARKS ON PREVENTIVE MEASURES_
GENERAL PRINCIPLES, SUBSTITUTES FOR DANGEROUS MATERIALS, CLEANLINESS OF
WORKROOMS, CUBIC SPACE, VENTILATION, REMOVAL OF DUST AND FUMES
Preventive measures against industrial poisoning aim at an unattainable
goal of so arranging industrial processes that employment of poisonous
substances would be wholly avoided. Such an ideal must be aimed at
wherever practicable. Prohibition of direct handling of poisonous
substances is also sometimes demanded, which presupposes (although it is
not always the case) that this is unnecessary or can be made unnecessary
by suitable mechanical appliances. We have to be contented, therefore,
for the most part, with removal of injurious dust and fumes as quickly
as possible at the point where they are produced, and regulations
for the protection of workers from industrial poisoning deal mainly
with the question of the prevention of air contamination and removal
of contaminated air. Substitution of non-injurious for injurious
processes is only possible in so far as use of the harmless process
gives technically as good results as the other. If such a substitute
can be found let it be striven for. Mention has already been made of
international prohibition of certain substances, and attention has been
drawn to economical considerations affecting this point.
Prohibition obviously may paralyse branches of industry and hit heavily
both employers and employed. The skilled trained workers are just the
ones to suffer, since they are no longer in a position to take up another
equally remunerative trade.
Judgment has to be exercised before enforcing new regulations in order
that good and not harm may follow. If a satisfactory substitute be
discovered for methods of work injurious to health, then ways and
means will be found to make the alteration in the process economically
possible. It may, however, demand sacrifice on the part of employers and
employed, but the progress is worth the sacrifice.
The following are instances of substitution of safe processes for those
involving risk: generation of dust can sometimes be avoided by a ‘wet’
method (watering of white lead chambers, grinding pulp lead with oil,
damping of smelting mixtures, &c.); the nitrate of silver and ammonia
process has replaced the tin and mercury amalgam used in silvering of
mirrors; electroplating instead of water gilding (coating objects with
mercury amalgam and subsequently volatilising the mercury); enamelling
with leadless instead of lead enamels; use of air instead of mercury
pumps in producing the vacuum in incandescent electric lamps.
Dealing further with the sanitation of the factory and workshop after
personal cleanliness, the next most important measure is cleanliness of
the workroom and purity of the air. Workrooms should be light and lofty;
and have floors constructed of smooth impervious material easily kept
clean. The walls should be lime-washed or painted with a white oil paint.
Angles and corners which can harbour dirt should be rounded. Cleansing
requires to be done as carefully and as often as possible, preferably by
washing down or by a vacuum cleaner. Saturation of the floor with dust
oil is recommended by some authorities in trades where poisonous dust is
developed and is permitted as an alternative to the methods described. I
refrain from expressing an opinion on this method of laying dust, since
by adoption of the practice insistence on the need for removal of the
poisonous material from the workrooms loses its force—a thing, in my
opinion, to be deprecated.
The necessity of keeping the atmosphere of workrooms pure and fresh
makes it essential that there should be sufficient cubic space per
person and that proper circulation of the air should be maintained. The
minimum amount of cubic space legally fixed in many countries—10-15
cubic metres—is a minimum and should be greatly exceeded where possible.
Natural ventilation which is dependent upon windows, porosity of building
materials, cracks in the floors, &c., fails when, as is desirable for
purposes of cleanliness, walls and floors are made of smooth impermeable
material, and natural ventilation will rarely supply the requisite cubic
feet of fresh air quickly enough. Ordinarily, under conditions of natural
ventilation, the air in a workroom is renewed in from one to two hours.
Artificial ventilation therefore becomes imperative. Natural ventilation
by opening windows and doors can only be practised in intervals of work
and as a rule only in small workrooms. During work time the draught and
reduction of temperature so caused produce discomfort.
_Artificial ventilation_ is effected by special openings and ducts
placed at some suitable spot in the room to be ventilated and arranged
so that either fresh air is introduced or air extracted from the room.
The first method is called propulsion, the latter exhaust ventilation.
Various agencies will produce a draught in the ventilating ducts, namely,
difference of temperature between the outside and inside air, which can
be artificially strengthened (_a_) by utilising the action of the wind,
(_b_) by heating the air in the exhaust duct, (_c_) by heating apparatus,
and (_d_) by mechanical power (use of fans).
Where advantage is taken of the action of the wind the exit to the
ventilating duct must be fitted with a cowl.
The draught in pipes is materially increased if they are led into furnace
flues or chimneys; in certain cases there is advantage in constructing
perpendicular ventilating shafts in the building extending above the roof
and fitted with cowls. Combination of heating and ventilation is very
effective.
[Illustration: FIG. 45.—Steam Injector (_after Körting_), showing steam
injector and air entry]
In workrooms, however, where there is danger of poisoning by far the
most effective method of ventilation is by means of fans driven by
mechanical power. All the means for securing artificial ventilation
hitherto mentioned depend on a number of factors (wind, difference of
temperature, &c.), the influence of which is not always in the direction
desired. Exact regulation, however, is possible by fans, and the quantity
of air introduced or extracted can be accurately calculated beforehand
in planning the ventilation. In drawing up such a plan, detailing the
arrangement, proportions of the main and branch ducts, expenditure of
power, &c., a ventilating engineer should be consulted, as it is his
business to deal with complicated problems of ventilation depending
entirely for success on the design of the ventilation.
Injectors are usually only employed for special technical or economical
reasons. A jet of steam or compressed air which acts on the injector
creates a partial vacuum and so produces a powerful exhaust behind. Fig.
45 shows the mechanism of an injector. They are used for exhausting acid
fumes which would corrode metal fans and pipes, and for explosive dust
mixtures where fans are inadmissible.
[Illustration: FIG. 46.—Propeller Fan coupled to Electromotor (_Davidson
& Co., Ltd._)]
In the industries described in this book fans are most commonly used.
These are, in the main, wheels with two or more wing-shaped flattened
blades. Some are encased, others are open and fitted by means of annular
frames in the ducts according to the intended effect and kind of fan.
Fans are of two kinds, propeller and centrifugal, and, according to the
pressure they exert, of low, medium, or high pressure. They are now often
driven electrically, in which case there is advantage in coupling them
directly with the motor.
_Propeller fans_ have curved screw-shaped blades and are set at
right angles in the duct upon the column of air in which they act by
suction. The air is moved in the direction of the axis of the fan, and
generally it is possible, by reversing the action, to force air in
instead of extracting it. The draught produced is a low-pressure one
(generally less than 15 mm. of water). The current of air set in motion
travels at a relatively slow speed, yet such fans are capable, when
suitably proportioned, of moving large volumes of air. Propeller fans
are specially suitable for the general ventilation of rooms when the
necessary change of air is not being effected by natural means.
[Illustration: FIG. 47.—The Blackman (Belt-driven) Fan.]
_Centrifugal_ or _high-pressure fans_ (see figs. 48A and 48B) are always
encased in such a way that the exhaust ducts enter on one or both sides
of the axis. The air thus drawn in is thrown by the quickly rotating
numerous straight blades to the periphery and escapes at the outlet.
The centrifugal fan travels at a great speed, and the air current
has therefore great velocity and high pressure. When the pressure is
less than 120 mm. it is described as a medium, and when greater, a
high-pressure fan. For the former a galvanised iron casing suffices;
for the latter the casing requires to be of cast iron. Medium pressure
centrifugal fans are used to exhaust dust or fumes locally from the point
at which they are produced. They play a great part in industrial hygiene.
[Illustration: FIG. 48A.—‘Sirocco’ Centrifugal Fan]
[Illustration: FIG. 48B.—Showing exhaust aperture and fan blades]
High-pressure fans are used mainly for technical purposes, as, for
example, the driving of air or gas at high pressure. Localised
ventilation is needed to limit diffusion of dust and fumes, which
is attained in a measure also by separation of those workrooms in
which persons come into contact with poisonous materials from others.
Separation of workrooms, however, is not enough, as it is the individual
who manipulates the poison for whom protection is desired. To enclose or
hood over a dusty machine or fume-producing apparatus completely, or to
close hermetically a whole series of operations by complicated technical
arrangements, is only possible when no opening or hand feeding is
required. Dangerous substances can only be wholly shut in by substitution
of machinery for handwork.
[Illustration: FIG. 49.—Localised Exhaust Ventilation in a Colour Factory
(_Sturtevant Engineering Co., Ltd._)]
[Illustration: FIG. 50A.
FIG. 50B.
Ball Mills]
Where, however, absolute contact is unavoidable the dust or fume must
be carried away at its source. This is done by exhaust ventilation,
locally applied, in the following manner: A suitable hood or air guide
of metal or wood is arranged over the point where the dust is produced,
leaving as small an opening as possible for necessary manipulations. The
hood is connected with a duct through which the current of air travels.
An exhaust current dependent upon heat will only suffice in the case
of slight development of dust or fumes. As a rule exhaust by a fan is
necessary. Where exhaust ventilation has to be arranged at several
points all these are connected up by branch ducts with the main duct
and centrifugal fan. Where the ducts lie near the floor it is advisable
to fix adjustable openings in them close to the floor to remove the
sweepings.
[Illustration: FIG. 51.—Ventilated Packing Machine (_after Albrecht_)
_A_ Worm; _B_ Collector; _D_ Fan; _E_ Filter bag; _J_, _F_ Movable
shutters; _H_ Jolting arrangement]
It is important for the exhaust system of ventilation to be designed
in general so that the dust is drawn away from the face of the worker
downwards and backwards. Many horrible arrangements are found in which
the dust is first aspirated past the mouth and nose before it is drawn
into a hood overhead. The proportions of the branch pipes to the main
duct require to be thought out, and friction and resistance to the flow
must be reduced as far as possible by avoidance of sharp bends. Branch
pipes should enter the main duct at an angle of thirty degrees. A
completely satisfactory system requires very special knowledge and often
much ingenuity when the apparatus is complicated.
Disintegrators and edge runners can generally be covered in and the cover
connected with an exhaust. Ball mills, when possible, are best as the
rotating iron cylinder containing the steel balls and the material to be
pulverised is hermetically closed.
Powdered material can be carried mechanically from one place to another
by worms, screws, endless bands, or be driven in closed pipes by means
of compressed air. The inevitable production of dust in packing can be
avoided by the use of ventilated packing machines, which are especially
necessary in the case of white lead, bichromates, basic slag, &c.
[Illustration: FIG. 52.]
The difficulty is great in preventing dust in sieving and mixing, since
this is mainly done by hand. Still here, for example, by use of cases
with arm-holes and upper glass cover, injury to health can be minimised.
Benches with a wire screen and duct through which a downward exhaust
passes are useful in sorting operations (fig. 52).
Fig. 53 illustrates a grinding or polishing wheel fitted with localised
exhaust.
[Illustration: FIG. 53.—Removing Dust from Bobs and Mops (_James Keith
& Blackman Co., Ltd. By permission of the Controller of H.M. Stationery
Office_)]
To prevent escape of injurious gases all stills and furnaces must be kept
as airtight as possible and preferably under a slight negative pressure.
Agitators must be enclosed and should be fitted with arrangements for
carrying on the work mechanically or by means of compressed air and, if
necessary, exhaust ventilation applied to them. The aim should be to
enclose entirely drying and extracting apparatus.
[Illustration: FIG. 54.—‘Cyclone’ Separator (_Matthews & Yates, Ltd._)]
An important question remains as to what shall be done with the dust and
fumes extracted. In many cases they cannot be allowed to escape into
the atmosphere outside, and in the interests of economy recovery and
utilisation of the waste is the thing to aim at. This vital subject can
only receive barest mention here. The dust or fumes extracted require to
be subjected to processes of purification with a view to recovery of the
often valuable solid or gaseous constituents and destruction of those
without value.
[Illustration: FIG. 55A. FIG. 55B.
Dust-filter of Beth-Lübeck (_after Albrecht_)]
[Illustration: FIG. 56.—Dust-filter of Beth-Lübeck—Detail]
Collection of dust may take place in settling chambers as in a cyclone
separator in which the air to be purified is made to travel round the
interior of a cone-shaped metal receptacle, depositing the dust in its
passage (see fig. 54).
[Illustration: FIG. 57.—Arrangement for Precipitating Dust (_after
Leymann_)
_A_ Entry of dust laden air; _B_ Fan; _C_ Purified air; _D_ Pipe carrying
away water and last traces of dust; _E_ Worm carrying away collection of
dust.]
The most effective method, however, is filtration of the air through
bags of canvas or other suitable fabric as in the ‘Beth’ filter (see
figs. 55 and 56). In the ‘Beth’ filter a mechanical knocking apparatus
shakes the dust from the bag to the bottom of the casing, where a worm
automatically carries it to the collecting receptacle. In the absence of
mechanical knocking the filtering material becomes clogged and increases
the resistance in the system. Contrivances of the kind unintelligently
constructed become a source of danger to the workers. Dust of no value
is usually precipitated by being made to pass through a tower down which
a fine spray of water falls. If the gases and fumes can be utilised they
are either absorbed or condensed—a procedure of the utmost importance for
the protection of the workers.
Condensation of the gases into a liquid is effected by cooling and is
an essential part of all processes associated with distillation. The
necessary cooling is effected either by causing the vapours to circulate
through coils of pipes surrounded by cold water or by an increase in the
condensing surface (extension of walls, &c.), and artificial cooling of
the walls by running water.
Absorption of gases and fumes by fluids (less often by solid substances)
is effected by bubbling the gas through vessels filled with the absorbing
liquid or conducting it through towers (packed with coke, flints, &c.),
or chambers down or through which the absorbent flows. Such absorption
towers and chambers are frequently placed in series.
The material thus recovered by condensation and absorption may prove to
be a valuable bye-product. Frequently the gases (as in blast furnace gas,
coke ovens, &c.) are led away directly for heating boilers, or, as in the
spelter manufacture, to make sulphuric acid.
V
_PREVENTIVE REGULATIONS FOR CHEMICAL INDUSTRIES_
Sulphuric Acid Industry
(See also pp. 4-14 and 171)
Danger arises from escape of acid gases or in entering chambers, towers,
containers, &c., for cleaning purposes. The whole chamber system,
therefore, requires to be impervious and the sulphur dioxide and nitrous
gases utilised to their fullest extent—a procedure that is in harmony
with economy in production. The pyrites furnace must be so fired as to
prevent escape of fumes, which is best attained by maintenance of a
slight negative pressure by means of fans. The cinders raked out of the
furnace because of the considerable amount of sulphur dioxide given off
from them should be kept in a covered-in place until they have cooled.
Any work on the towers and lead chambers, especially cleaning operations,
should be carried out under strict regulations. Such special measures
for the emptying of Gay-Lussac towers have been drawn up by the Union
of Chemical Industry. Before removal of the sediment on the floor they
require a thorough drenching with water, to be repeated if gases are
present. Perfect working of the Gay-Lussac tower at the end of the
series of chambers is essential to prevent escape of acid gases. In a
well-regulated sulphuric acid factory the average total acid content of
the final gases can be reduced to 0·1 vol. per cent. Under the Alkali
Works Regulation Act of 1881 the quantity was limited to 0·26 per cent.
of sulphur dioxide—and this should be a maximum limit.
_Entering and cleaning out chambers and towers_ should only be done, if
practicable, by workmen equipped with breathing apparatus, and never
without special precautionary measures, as several fatalities have
occurred at the work. Towers, therefore, are best arranged so as to allow
of cleaning from the outside; if gases are noticed smoke helmets should
be donned. The same holds good for entering tanks or tank waggons. After
several cases of poisoning from this source had occurred in a factory the
following official regulations were issued:
The deposit on the floor of waggons or tanks shall be removed
either by flushing with water without entering the tank itself,
or if the tank be entered the deposit is to be scooped out
without addition of water or dilute soda solution.
Flushing out shall only be done after the workmen have got out.
Workmen are to be warned every time cleaning is undertaken that
poisonous gases are developed when the deposit on the floor is
diluted.
Acid eggs, further, are to be provided with a waste pipe and
manhole to enable cleaning to be done from outside.
The poisoning likely to arise is partly due to arsenic impurity
(development of arseniuretted hydrogen gas) in the sulphuric acid used.
Unfortunately arsenic free acid is very difficult to obtain.
Hydrochloric Acid—Saltcake and Soda Industries
(See also pp. 15-23 and 170)
Preventive measures here depend upon observance of the general principles
already discussed.
The _saltcake pan_ and reverberatory furnace require to be accurately and
solidly constructed and the process carefully regulated. Regulations
indeed were drawn up at an early date in England as to their working
to prevent escape of gases when adding the acid, raking over in the
reverberatory furnace, and withdrawal of the still fuming saltcake.
The following are the most important of these recommendations:
The saltcake pan must not be charged when overheated.
Sulphuric acid shall be added only after all the salt has been
charged and the door shut.
If hydrochloric acid fumes escape at the door when the Glover
acid flows in the flow must be interrupted.
All doors must be closed while work is in progress.
Definite times shall be fixed for withdrawal of the saltcake in
order to try and ensure that it be not still fuming, but should
this be the case cold sulphate of soda shall be sprinkled over
it.
The general principle should be observed of maintaining a slight negative
pressure in the furnace by insertion of a fan in the gas conduit so as to
avoid possible escape of gas. The fuming saltcake is best dealt with by
depositing it at once to cool in ventilated receptacles or chambers.
On grounds of economy and hygiene as complete an absorption as possible
of the hydrochloric acid gas developed in the saltcake and soda ash
process is to be aimed at, by conveying it through impervious conduits
to the bombonnes and lofty absorption tower filled with coke or flints
down which water trickles. The entire loss of hydrochloric acid should
not amount to more than 1·5 per cent. of the whole. Under the Alkali Act
at first 5 per cent. was allowed, but this is excessive now in view of
improved methods of condensation.
In the _Leblanc_ process the revolving furnace is on health grounds to
be preferred to the hand furnace. Such a furnace occupies the space
of but three hand furnaces and can replace eighteen of them. The vast
accumulation of waste, consisting mainly of calcium sulphide, and
generating sulphuretted hydrogen gas in such amount as to constitute
a nuisance, is only partially prevented by the Chance-Claus and other
methods of recovery, and makes it most desirable to adopt the Solvay
ammonia process.
_Note._—_Sulphonal, Oxalic acid, Ultramarine, Alum._—The production of
_sulphonal_ is intensely unpleasant owing to the disagreeable smell (like
cats’ excrement) of the mercaptan developed. All work therefore must be
carried on in air-tight apparatus under negative pressure and careful
cooling. Any escaping fumes must be absorbed in solution of acetone and
fine water spray.
Preparation of _oxalic acid_ unless carried on in closed-in vessels gives
rise to injurious and troublesome fumes. If open pans are used, hoods and
ducts in connection with a fan should be placed over them.
Grinding of _ultramarine_ and _alum_ requires to be done in closed-in
mills, and any dust drawn away by locally applied ventilation and
filtered. The gases given off in the burning process contain 3 per cent.
of sulphur dioxide, which requires to be absorbed—a procedure most easily
effected in towers where the upstreaming gas comes into contact with a
dilute solution of lime or soda.
Chlorine, Bleaching Powder, Chlorine Compounds
(See also pp. 23-9 and 173)
What has been said as to imperviousness of apparatus, negative pressure
maintained by the tall chimney stack or earthenware or fireclay fan,
&c., applies equally here. The exhaust ventilation is also required to
aspirate the gas into the bleaching chambers.
At the end of the system there must be either a tower packed with
quicklime to absorb the last traces of chlorine or such a number of
bleach chambers into which the gas can be led that no chlorine escapes.
Production of chlorine gas electrolytically is to be preferred to other
processes on hygienic grounds.
Careful cleanliness is the best prophylactic against occurrence of
_chlorine rash_ among persons employed in the electrolytic production of
chlorine. In some factories attempt has been made to use other substances
(magnetite) instead of carbon for the anode, and the success attending
their adoption is further proof that the tar cement at the anode helped
to cause the acne.
In the _Weldon_ process care must be taken that the water lutes are
intact, and the stills must not be opened before the chlorine has been
drawn off. All processes in which manganese dust can arise (grinding
of manganese dioxide and drying of Weldon deposit) should be done
under locally applied exhaust. The _bleaching powder_ chambers must be
impervious and care taken that they are not entered before the chlorine
has been absorbed. Usually the number of lime chambers connected up with
each other is such that no chlorine escapes free into the air. Emptying
of the finished product should not be done by hand, as considerable
quantities of chlorine escape and make the work extremely irksome.
Mechanical methods of emptying should be adopted in substitution for hand
labour, and of these the Hasenclever closed-in apparatus is the best.
Nitric Acid and Explosives
(See also pp. 39-49 and 172)
In the production of _nitric acid_ complete imperviousness of the system
and as complete condensation of the gases as possible by means of
tourilles, cooling condensers, and the requisite number of towers are
necessary. The method suggested by Valentine of manufacture of nitric
acid in apparatus under a partial vacuum has advantages from a hygienic
standpoint. Earthenware fans are used to force the nitric acid gases
onwards and have the advantage of creating a negative pressure. Great
care is needed in handling, emptying, packing, conveying, and storing the
acid in consequence of the danger from breaking or spilling. The bottles
used must be in perfect condition and must be well packed. No greater
stock of nitric acid should be allowed in a room than is absolutely
necessary, and care must be exercised in the event of a carboy breaking
that the spilt acid does not come into contact with organic substances,
as that would increase development of nitrous fumes.
Workers must be warned not to remain in rooms in which acid has been
spilt. They are only to be entered by workers equipped with breathing
apparatus (smoke helmets).
Among the special regulations on the subject may be mentioned those
of the Prussian Ministerial Decree, dated January 8, 1900, concerning
nitrous fumes and means of protection for workers employed with the acid.
What has been said on p. 257 in regard to the transport of sulphuric acid
applies equally to nitric acid.
In the _nitrating_ process in the manufacture of explosives (see p.
47) it is essential that the apparatus is hermetically closed, that
agitation is done mechanically, or better still by means of compressed
air, and that any fumes developed are exhausted and condensed. In the
preparation of _nitro-glycerin_ (see p. 46) the gases developed in the
nitration of the waste acid require to be carefully condensed. Contact
of nitro-glycerin with the skin has to be avoided and the attention
of the workers drawn to the danger. Preparation of _gun cotton_ (see
p. 48) takes place in machines which are at the same time nitrating
and centrifugalising machines. The apparatus is first filled with
the nitrating acid and the cotton added; the fumes are drawn off by
earthenware ducts and fans, and lastly the bulk of the acid is removed by
centrifugal action. Such machines carry out effectually the principles of
industrial hygiene.
In the preparation of _fulminate of mercury_ nitrous fumes, cyanogen
compounds, and acetic acid compounds are developed by the action of
the nitric acid on mercury, and require to be dealt with by exhaust
ventilation.[G]
Artificial Manures, Fertilizers
(See also pp. 53 and 54)
In grinding phosphorite and superphosphates, corrosive dust is produced.
All grinding operations must, therefore, be carried out automatically
in closed apparatus (ball mills, disintegrators, &c.). In making the
phosphorite soluble by treatment with sulphuric acid, and subsequent
drying of the product, corrosive hydrofluoric acid gas is developed,
which requires to be carried away by an acid proof exhaust fan, and
condensed in a tower by water (see fig. 58). The modern revolving drying
machines are especially serviceable.
[Illustration: FIG. 58.—Washing tower for hydrofluoric acid (_after
Leymann_.)]
In the production of _basic slag_ corrosive dust is given off, causing
ulceration of the mucous membrane. Grinding and other manipulations
creating dust must be carried on in apparatus under local exhaust
ventilation. The following—somewhat shortened—are the German Imperial
Regulations, dated July 3, 1909, for basic slag factories.
BASIC SLAG REGULATIONS
1. Workrooms in which basic slag is crushed, ground, or stored
(if not in closed sacks) shall be roomy and so arranged as to
ensure adequate change of air. Floors shall be of impervious
material allowing of easy removal of dust.
2. Preliminary breaking of the slag by hand shall not be done
in the grinding rooms, but either in the open air or in open
sheds.
3. Slag crushers, grinding mills, and other apparatus shall be
so arranged as to prevent escape of dust as far as possible
into the workrooms. They shall be provided with exhaust
ventilation and means for collecting the dust if this cannot be
done in the absence of dust.
4. Arrangements shall be made whereby barrows conveying
material to the grinding mills shall be emptied directly into
partially hooded hoppers provided with exhaust ventilation so
as to prevent escape of dust into the workrooms.
5. The casing and joints of the grinding mills, ducts, dust
collectors and sieves shall be airtight; if leaks are noticed
they must be repaired forthwith.
6. Ducts, dust collectors and sieves shall be so arranged as to
enable periodical cleansing to be undertaken from the outside.
7. Repairs of the plant mentioned in Para. 5 in which workers
are exposed to inhalation of slag dust shall be entrusted by
the occupier only to such workers as wear respirators supplied
for the purpose or other means of protecting mouth and nostrils
such as wet sponges, handkerchiefs, &c.
8. Emptying of slag powder from the grinding mills and dust
collectors and transference to the store rooms shall only
be done in accordance with special regulations designed to
minimise dust.
9. Filling slag powder into sacks from the outlets of the
mills, elevating and discharging it into receptacles shall only
be done under efficient exhaust ventilation.
10. Sacks in which the powder is transported and piled in heaps
shall be of a certain defined strength to be increased in the
case of sacks to be piled in heaps more than 3½ metres in
height. Special rooms separated from other workrooms shall be
provided for storage of slag powder in sacks. Only the sacks
representing the previous day’s production may be stored in the
grinding rooms.
Basic slag in powder and not in sacks shall be kept in special
storage rooms shut off entirely from other workrooms. No person
shall enter such storage rooms when they are being filled or
emptied. Discharging the contents of the sacks into them shall
be done under exhaust ventilation.