Chapter XV: Part III: Preventive Measures Against Industrial Poisoning (2)

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.

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.

11. The floors of the workrooms described in Para. 1 shall be
cleaned before the commencement of each shift or in an interval
during each shift. No person except those engaged in cleaning
shall be present during the operation. If cleaning is effected
by sweeping, the occupier shall require the persons doing it to
wear the respirators provided or other protection for the mouth
and nose.

12. The occupier shall not permit the workers to bring spirits
into the factory.

13. A lavatory and cloakroom and, separated from them and in
a part of the building free from dust, a meal room shall be
provided. These rooms shall be kept clean, free from dust, and
be heated during the winter.

In the lavatory and cloakroom water, soap, and towels shall be
provided and adequate arrangements shall be made for keeping
the clothing taken off before commencing work.

The occupier shall give the persons employed opportunity to
take a warm bath daily before leaving work in a bathroom
erected inside the factory and heated during the winter.

14. No woman or male young person under eighteen years of age
shall work or remain in a room into which basic slag is brought.

Persons under eighteen years of age shall not be employed in
beating sacks which have contained basic slag.

15. No person employed in breaking or grinding, emptying,
packing, or storing basic slag, shall work more than ten hours
daily.

There shall be intervals during working hours amounting in the
aggregate to two hours, one of them lasting at least an hour.
If duration of employment daily is limited to seven hours with
never longer than four hours’ work without an interval, only
one interval of at least one hour is required.

16. For work mentioned in Para. 15 no person shall be employed
without a certificate from an approved surgeon stating that he
is free of disease of the lungs and not alcoholic. The occupier
shall place the supervision of the health of the workers under
a surgeon who shall examine them at least once a month for
signs of disease of the respiratory organs and alcoholism.
Workers engaged in the operations mentioned in Para. 15 shall
be suspended from employment when the surgeon suspects such
illness or alcoholism. Those showing marked susceptibility to
the effect of basic slag dust shall be permanently suspended.

17. A health Register shall be kept in which shall be entered
the precise employment, duration of work, and state of health
of the persons employed.

18. The occupier shall obtain a guarantee from the workers that
no alcohol or food shall be taken into the workrooms.

Preparation of Hydrofluoric Acid

(See also pp. 37 and 171)

The fumes given off in the preparation of hydrofluoric acid require to be collected in leaden coolers and vessels; that which escapes requires to be absorbed by a water spray in towers. The apparatus must be impervious and kept under a slight negative pressure.

Chromium Compounds

(See also pp. 55-8 and 185)

The German Imperial Decree, dated May 16, 1907, contains the preventive measures necessary in bichromate factories. According to this, workers suffering from ulceration of the skin (chrome holes, eczema) are not to be employed except on a medical certificate that they are free from such affections, and daily examination for signs of ulceration is enjoined, so that those affected may receive prompt treatment. Further, periodical medical examination of the workers is required at monthly intervals. Respirators (for work in which dust cannot be avoided), with lavatory, cloakroom, and meal room accommodation, are to be provided, and also baths. In handling bichromates wearing of impervious gloves may be necessary, and smearing the hands and face with vaseline is recommended. In addition diffusion of dust and fumes must be minimised; machines in which mixing, crushing, and grinding are done must be impervious, and provided with exhaust ventilation. Charging of the furnaces, where possible, should be effected mechanically and the fumes developed both in manipulation of the furnaces and from hot bichromate liquor removed by an exhaust.

A leaflet containing directions for workers coming into contact with chromium compounds in chemical factories, dyeing, tanning, wood staining, calico printing, wall paper printing, painting, &c., has been drawn up by Lewin. It contains a list of the poisonous chrome compounds and of the industries in which chrome poisoning occurs, information as to the action of chrome upon the skin and mucous membrane, and the preventive measures necessary. Among the last named are: smearing the skin with oil, use of impervious gloves, respirators in work where dust arises, necessity of cleanliness, and periodical medical examination.

For the _chrome tanning industry_ the following leaflet was drawn up by the Imperial Health Office in Berlin, which succinctly states the measures against chrome poisoning in these industries and contains much practical information for the workers:

In chrome tanning by the two bath process, the first bath
containing potassium bichromate and hydrochloric acid has a
corroding effect upon broken surfaces of the skin (scratches,
chapped hands, eruptions, &c.). In consequence, they develop
into round ulcers (chrome holes) with hard raised edges which
are difficult to heal and go on increasing in size unless work
at the process is temporarily given up. In persons with very
sensitive skin, even though the surface may be intact, handling
the liquor brings on sometimes an obstinate rash (eczema) on
the hands and forearms.

The solution used in the one bath process has no corrosive
action, but it is a strong poison, just as is the solution of
potassium bichromate of the two bath process. If swallowed, the
solutions cause vomiting, diarrhœa, kidney trouble, and even
death. Chromium compounds can also enter the body through skin
wounds and cause illness.

_Prevention._—In order to prevent the occurrence of chrome
ulceration, workers employed with chrome or chrome solutions
must be especially careful in avoiding injury to the skin of
the hands or forearms. This applies especially to workers who
carry the vessels containing bichromate, who weigh and dissolve
the potassium bichromate, or who come into contact with the
tanning liquor or with undressed skins and hides which have
lain in the liquor.

If, in spite of precautions, eruptions, rashes, or ulceration
occur, all work necessitating contact with corrosive tanning
liquors should be suspended until they are healed.

In order to reduce risk of action of the liquor on the skin,
workers employed in the process described would do well if,
before commencing work, they carefully smeared hands and
forearms with unsalted lard, vaseline, or the like, and during
work avoided, as much as possible, soiling the bare hands and
arms with the liquor.

If, nevertheless, a worker has contracted a chrome hole, or
eruption, he should consult a medical man, informing him at the
same time of the nature of his work.

To avoid internal absorption of chrome, workers preparing the
baths must carefully avoid inhaling the dust of chromium salts.
These and all other workers engaged with the liquors containing
chromium must not take food and drink while at work. Working
suits should be taken off and face and hands washed with soap
before eating or drinking, and before leaving the factory.

Petroleum, Benzine

(See also pp. 59-64 and 222-4)

As crude petroleum and the higher fractions first distilled from it affect the skin injuriously, wetting the skin should be avoided, and careful cleanliness on the part of the workers enjoined. Workers exposed to the influence of gases escaping from naphtha springs and wells should be equipped with breathing apparatus (smoke helmets); this applies to those who have to enter stills and other apparatus connected with the distillation of petroleum.

In the preparation of petroleum by sulphuric acid sulphur dioxide in great quantity is developed, constituting a distinct danger to the workers. This process, therefore, should be carried on in closed vessels furnished with mechanical stirrers or compressed air agitators. The most suitable apparatus is that illustrated in fig. 13.

Petroleum tanks must be thoroughly aired before they are cleaned and should be entered only by workers equipped with breathing apparatus. Apparatus containing petroleum and benzine requires, as far as possible, to be closed in and air tight (as, for example, in the extraction of fat from bones and oil seed, in the rubber industry, and in chemical cleaning establishments); where benzine fumes develop they should be immediately drawn away by suitably applied exhaust ventilation. This is necessary, on account of the danger of fire, in chemical cleaning establishments where purification is effected by means of benzine in closed drums.

Regulations for benzine extraction plants are contained in the Prussian Ministerial Decree, dated January 5, 1909, for benzine extraction works, and also in that of August 3, 1903, for dry-cleaning premises, to which last were added ‘Directions for safety,’ containing important regulations as to risk from fire. From our standpoint the following points are of interest: care is to be taken to provide and maintain exhaust ventilation directly across the floor. The air, however, must not be allowed to pass near any fire. Drying rooms especially are to be lofty and airy, and separated from other workrooms. In factories with mechanical power the authorities may require provision of artificial ventilation for the drying rooms. Washing machines, centrifugalising machines, and benzine rinsing vessels should be furnished with well-fitting covers to be removed only for such time as is absolutely necessary for putting in and taking out the articles to be cleaned, shaken, or rinsed. The vessels named are to be examined as to their imperviousness at least once every quarter by a properly qualified person. The condition in which they are found is to be noted in a book to be shown to the Factory Inspector and police authorities on demand.

Lastly, substitution for benzine of other less poisonous substances such as carbon tetrachloride has been urged.

Phosphorus, Lucifer Matches

(See also pp. 49-53 and 190)

In view of the danger of the lucifer match industry, measures were taken at an early date in almost all civilised states to guard against phosphorus poisoning, and in many countries have led to the prohibition of the use of white phosphorus. Complete prohibition of its manufacture and use was first enacted in Finland (1872) and in Denmark (1874). Prohibition was decreed in Switzerland in 1879 (in January 1882 this was revoked, but again enacted in 1893), and in the Netherlands in 1901. In Germany the law prohibiting the use of white phosphorus came into force in January 1908, and runs as follows:

1. White or yellow phosphorus shall not be employed in the
production of matches and other lighting substances. Lighting
substances made with white phosphorus shall not be kept for
sale, or sold, or otherwise brought on the market. Provided
that this shall not apply to ignition strips which serve for
the lighting of safety lamps.

2. Persons wilfully infringing this law shall be punished
by a fine of 2000 marks. If the infringement occurs through
ignorance the fine shall consist of 150 marks.

In addition to the fine, all prohibited articles produced,
imported, or brought into the trade shall be confiscated,
as well as the implements used in their production, without
reference to whether they belong to the person convicted or
not. If prosecution or conviction of the guilty party cannot be
brought home, confiscation nevertheless is to be carried out
independently.

Roumania and France have a state monopoly of matches; in these states no white phosphorus matches have been produced since 1900 and 1898 respectively. France, by the Law of December 17, 1908, signified concurrence with the International Convention in regard to the prohibition of the use of white phosphorus.

In Sweden and Norway the prohibition of white phosphorus is in force only for the home trade. A Swedish Decree, dated December 9, 1896, permitted factories carrying on the manufacture for export to use white phosphorus, and almost precisely similar provisions are contained in the Norwegian Decree. The Swedish Decree, dated March 30, 1900, permits white phosphorus matches to be exported, but not to be sold in the country. In Austria difficulties in regard to prohibition of white phosphorus arose owing to trade conditions (especially in the East), and the attitude of the states competing in the lucifer match trade, particularly Italy and Japan. Austria, therefore, made agreement with international prohibition of white phosphorus, dependent on the attitude of Japan; since Japan did not concur, the decision of Austria fell through. When, however, Italy in the year 1906 joined the Convention, the difficulties were also overcome in Austria, and by a law similar to that of Germany, dated July 13, 1909, prohibition of the manufacture and sale of white phosphorus matches dates from the year 1912.[H]

Belgium has refrained from prohibition of white phosphorus, but on the other hand has passed a series of enactments relating to the match manufacture, of which the most essential are here cited, since they characterise the measures which come into consideration for factories in which white phosphorus is still employed.

_Royal Decree, dated March 25, 1890, modified by the Royal
Decree, dated February 12, 1895, and November 17, 1902,
concerning employment in lucifer match factories._

1. In match factories where white phosphorus is used, mixing
the paste and drying the dipped matches shall be carried on in
a place specially set apart for the purpose.

2. Mixing the paste shall be carried on in an entirely closed
vessel or in one connected with an efficient exhaust draught
locally applied.

The proportion of white phosphorus in the paste shall not
exceed in weight 8 per cent. of the total material, not
including water.

3. Hoods and ducts communicating with an exhaust draught shall
be installed at the level of the plates for dipping white
phosphorus matches, and over the vessels containing the paste.

4. Drying rooms for white phosphorus matches, if entered by the
workers, shall be mechanically ventilated.

5. Rooms in which phosphorus fumes can arise shall be lofty and
well ventilated, preferably by an exhaust at the level of the
work benches, communicating with the main chimney stack.

The workrooms shall be kept clean. No food or drink shall be
taken in them.

6. In every match factory the workers shall have at their
disposal a special cloak room and suitable and sufficient
washing accommodation, so as to be able to change clothes
before commencing, and at the end of, work, and to wash the
hands and face on leaving.

Cleanliness will be obligatory upon the workers manipulating
phosphorus paste or matches.

7. Workers coming into contact with phosphorus paste or matches
shall be examined monthly by a surgeon appointed by the
Minister of Industry, who shall be paid by the occupier.

Workers having decayed, unstopped teeth, or exhibiting symptoms
of gingivitis or stomatitis, or in poor health at the time of
examination, shall be temporarily suspended from work.

The surgeon shall enter the results of his monthly examinations
in a prescribed register.

This register shall be shown to the Factory Inspector on demand.

These decrees are supplemented by further orders regarding the taking of samples of paste in match factories and store houses (Royal Orders of March 25, 1890; February 12, 1895; April 18, 1898; November 17, 1902).

As is evident from the Belgian enactment, in states where prohibition of white phosphorus is not in force, palliative measures only are possible and even then they can only be enforced in large factories when automatic machinery is used to eliminate hand labour in dangerous operations. In this respect the introduction of closed, ventilated, mechanical mixing apparatus provided with mechanical stirrers, closed and ventilated mechanical dipping and drying apparatus, are especially important. Certain modern American machines carry through the whole complicated process of the phosphorous match industry automatically. Seeing that prohibition of white phosphorus is an accomplished fact and that matches free from risk in their manufacture answer every purpose, the universal enforcement of the prohibition of white phosphorus should be striven for in civilised states.

Carbon bisulphide

(See also pp. 68-71 and 193-5)

Use of carbon bisulphide in the vulcanising of indiarubber goods by dipping them into the liquid and subsequently drying them (usually in a current of hot air) causes development of carbon bisulphide fumes in considerable quantity, especially if the articles to be dried are laid on shelves or hung up in the workroom, a procedure which should never be permitted. Drying must be carried out under local exhaust ventilation.

All vessels holding carbon bisulphide used for dipping can be placed in a wooden channel above the dipping vessels, provided with openings for manipulation, and connected with an exhaust system.

The following are the German Imperial Regulations, dated March 1, 1902, for vulcanising of indiarubber by means of carbon bisulphide:

VULCANISING BY MEANS OF CARBON BISULPHIDE

(Notice concerning the erection and management of industrial
premises in which indiarubber goods are vulcanised by means of
carbon bisulphide or chloride of sulphur.)

The following regulations shall apply in accordance with
paragraph 120 (_e_) of the Industrial Code:

1. The floor of such rooms as are used for the vulcanising
of indiarubber goods by means of carbon bisulphide shall not
be lower than the surrounding ground. The rooms shall have
windows opening into the outer air, and the lower halves shall
be capable of being opened so as to render possible sufficient
renewal of air.

The rooms shall be ventilated by fans mechanically driven. With
the approval of the higher authorities permission to dispense
with mechanical draught may be allowed, provided that in other
ways powerful change of air is secured. With the approval of
the higher authorities special ventilating arrangements can be
dispensed with if the fumes of carbon bisulphide are removed
immediately, at the point where they are produced, by means
of a powerful draught, and in this way purity of the air be
secured.

2. The vulcanising rooms shall not be used as a dwelling, or
for sleeping in, or for preparing food in, or as a store,
or drying room, nor shall other processes than those of
vulcanising be carried on in them. No persons, except those
engaged in vulcanising processes, shall be allowed in the rooms.

There shall be at least 20 cubic meters (700 cubic feet) of air
space allowed for each person employed therein.

3. Only such quantities of carbon bisulphide shall be brought
into the vulcanising rooms as shall serve for the day’s supply.
Further storage shall be made in a special place separate from
the workrooms. Vessels to hold the vulcanising liquid shall be
strongly made, and when filled and not in use shall be well
covered.

4. Vulcanising and drying rooms shall be warmed only by steam
or hot-water pipes.

These rooms shall be lighted only by means of strong
incandescent electric lamps.

Exceptions from paragraphs 1 and 2 may be allowed by the higher
authorities.

5. Machines intended for vulcanising long sheets of cloth shall
be covered over (_e.g._, with a glass casing) so as to prevent
as far as possible the entrance of carbon bisulphide fumes into
the workrooms, and from the casing the air shall be drawn away
effectually by means of a fan mechanically driven. Entrance to
the space which is enclosed shall only be allowed in case of
defects in the working.

In cases where a covering of the machine is not practicable
for technical reasons the higher authorities can, if suitable
means of protection are used (especially when the machine is
placed in an open hall, and provided that no person works at
the machine for more than two days a week), allow of exception
to the above arrangement.

6. Vulcanising of other articles (not mentioned in par. 5),
unless carried out in the open air, shall be done in covered-in
boxes into which the worker need only introduce his hands, and
so arranged as to keep the fumes away from the face of the
worker.

The air must be drawn away from the box by means of a powerful
draught.

7. Rule 6 shall apply in vulcanising both the outside and
inside of indiarubber goods. In vulcanising the inside no
worker shall be allowed to suck the fluid through with the
mouth.

8. The goods after their immersion in the vulcanising fluid
shall not lie open in the room, but shall either be placed
under a ventilated cover or at once be carried into the drying
chamber.

The drying chamber or drying rooms in which the wares are
exposed to artificial heat immediately after vulcanising
shall be so arranged that actual entrance into them for the
putting in or taking out of the vulcanised goods shall not
be necessary. No person shall be allowed to enter the drying
chamber while work is going on. The higher authorities can
permit of exceptions to this rule in the case of the drying of
long rolls if sufficient protecting arrangements are made.

9. When vulcanisation is effected by means of chloride of
sulphur the vessels or chambers used for holding it shall be so
arranged that escape of the fumes is prevented.

No person shall enter the vulcanising chamber until the air in
the chamber has been completely changed; it shall not be used
for purposes other than vulcanising.

10. Employment in vulcanising with carbon bisulphide or in
other work exposing the workers to carbon bisulphide vapour
shall not be allowed without a break for more than two hours
and in no case for more than four hours in one day; after two
hours a pause of at least one hour must be allowed before
resumption.

No person under 18 years of age shall be employed.

11. The occupier shall provide all workers employed in work
mentioned in paragraph 10 with proper and sufficient overalls.
By suitable notices and supervision he shall see that when not
in use they are kept in their proper place.

12. Separate washing accommodation and dressing-rooms for each
sex shall be provided, distinct from the workrooms, for all
persons employed as stated in paragraph 11.

Water, soap, and towels and arrangements for keeping the
clothes put off before the commencement of work shall be
provided in sufficient amount.

13. The occupier shall appoint a duly qualified medical
practitioner (whose name shall be sent to the Inspector of
Factories) to supervise the health of those exposed to the
effects of carbon bisulphide. He shall examine the workers once
every month with a view to the detection of poisoning by carbon
bisulphide.

By direction of the medical practitioner workers showing signs
of carbon bisulphide poisoning shall be suspended from work
and those who appear peculiarly susceptible shall be suspended
permanently from work in processes mentioned in paragraph 10.

14. The occupier shall keep a book, or make some official
responsible for its keeping, of the changes in the personnel in
the processes mentioned in paragraph 10 and as to their state
of health. The book shall contain—

(1) The name of the person keeping the book;

(2) The name of the appointed surgeon;

(3) Surname, Christian name, age, residence, date of first
employment, and date of leaving of every worker mentioned in
paragraph 10, and the nature of the employment;

(4) The date of any illness and its nature;

(5) Date of recovery;

(6) The dates and results of the prescribed medical examination.

15. The occupier shall require the workers to subscribe to the
following conditions:—

No worker shall take food into the vulcanising rooms;

The workers shall use the protection afforded in paragraphs 5-7
and use the overalls in the work named;

The workers shall obey the directions of the occupier given in
accordance with Rule 5, paragraphs 1 and 2, Rule 8, paragraphs
1 and 2, and Rule 9, paragraph 2. Workers contravening these
orders shall be liable to dismissal without further notice.

If in a factory regulations already exist (paragraph 134(a) of
the Industrial Code) the above shall be included.

16. In the vulcanising rooms mentioned in Rule 1 there shall be
posted up a notice by the police stating—

(_a_) The cubic capacity of the rooms;

(_b_) The number of workers who may be employed.

Further, in every vulcanising room there shall be posted up in
a conspicuous place and in clear characters Rules 1-15 and the
conditions in paragraph 15.

Reference should be made also to the Prussian Ministerial Decree, dated February 23, 1910, on the preparation, storing, and manufacture of carbon bisulphide, and to the French Ministerial Circular, dated January 20, 1909 (Manufacture of Indiarubber).

Employment of benzine and chloride of sulphur for vulcanising is, from a hygienic standpoint, to be preferred to that of the much more dangerous carbon bisulphide. The same applies also to the process of the extraction of fat.

In the references made to general arrangements for the protection of workers dealing with poisons, stress was laid on the complete enclosing of extraction apparatus. This applies, of course, to extraction by means of carbon bisulphide, both on grounds of economy, health, and risk from fire.

On account of the risk to health, efforts have been made to substitute other means of equal efficiency, free from danger. Such a substitute may be found in _carbon tetrachloride_. This extracts well, and dissolves grease spots (like benzine), is not explosive, is scarcely inflammable, and is less poisonous than the substances commonly used for extraction. Its employment is to be recommended on hygienic grounds, but the relatively high price may stand in the way of its use.

Illuminating Gas Industry. Production of Tar and Coke

(See also pp. 71-90 and 199)

In illuminating gas factories imperviousness of the whole working system is especially important from an economical and hygienic standpoint, since only in this way can danger to the working staff be avoided. This applies especially to the retorts, from which no gas should be allowed to escape. If the exhaust is working satisfactorily this should not be possible, as the pressure of the gas in the retorts during distillation will be a negative one. Correct regulation of pressure is thus of the greatest importance in the prevention of poisoning in gas works.

Further, special precaution is necessary in operations with gas purifying material containing cyanogen, since otherwise the workers suffer from the gases developed from the gas lime.

Work with gas purifying material should be so arranged that injurious gases are carried away by suitable ventilating arrangements. Consideration for the neighbourhood forbids their discharge into the open air, and forbids also operations with the gas purifying material in the open air; therefore non-injurious removal of these gases is necessary.

Quenching of the coke also should, on account of the annoyance to the working staff and to lessen nuisance to the neighbourhood, be carried out so that the fumes are drawn into the main chimney stack.

In coke ovens escape of tarry constituents and of poisonous emanations are prevented by imperviousness of the apparatus, by sufficiency of the exhaust draught, and especially by passing the products of distillation, which cannot be condensed, under a fire, or by absorbing them either with water or oil.

Special precautionary measures are needed further in the distillation of the washing oil, and generally escape of poisonous emanations must be prevented by the greatest possible imperviousness of the distillation system and corresponding regulation of pressure.

Gas Motors (Power Gas Stations)

(See also pp. 80-5)

The following points, taken from an Austrian Ministerial Decree (dated December 2, 1903), for the prevention of poisoning in power gas works, may be useful:

POWER GAS INSTALLATIONS

In mixed gas installations (Dowson, water gas) of the older
system, the way in which the gas is produced causes the whole
apparatus and pipes to be under slight negative pressure,
because the steam required for the process must be blown into
the generator. In these works, therefore, a small special steam
boiler is required and a gas receiver to store the gas.

In more modern suction generator gas installations the piston
is used to suck in steam and air as well as the gases arising
in the generator and to draw them into the motor cylinder. Thus
the whole system is kept in a condition of slight negative
pressure during the process. While the suction generator gas
system is working, only so much gas is produced as the motor
uses for the time being, so that with this system there is no
greater store of gas than is requisite.

In such an installation the following rules should be borne in
mind:

1. All the apparatus (gas pipes, valves, &c.) must be
constructed and maintained in a completely impervious
condition. Any water seals especially which may be in use must
receive attention.

2. Precautions must be taken to prevent the gases from the
generator passing into the coolers and purifiers when the
engine is at rest.

3. Care is to be taken when the apparatus is at rest to prevent
any possible subsequent escape of gas into the room where the
apparatus is installed.

4. The return of explosive gas out of the gas engine into the
gas pipe by failure to ignite or other accident, must be made
impossible.

5. The apparatus through which the generator is charged must
possess a tightly fitting double valve to prevent escape of gas
into the room during charging.

6. The pipes for conducting away the unpleasantly smelling
bituminous constituents in the water mixed with sulphuretted
hydrogen from the scrubbers must not communicate with the
workroom.

7. Precautions must be taken to minimise the danger during the
cleaning of the generator (removal of ashes and slag).

8. All stop-cocks and valves are to be so arranged that their
position at any time (open or shut) is clearly visible from
outside.

9. Purifiers with a capacity greater than two cubic meters
must be provided with appliances which make possible thorough
removal of the gas before they are opened.

10. The gas washing and cleaning apparatus and pipes are to be
fitted with gauges indicating the pressure existing in them at
any moment.

11. When a suction gas plant is first installed and also at
times when there is no gas in the pipes and plant between the
generator and the engine, gas must be blown in until all air is
expelled before the engine is set going.

12. During the cleaning of apparatus and pipes which, when in
action, contain gas, the rooms must be thoroughly ventilated.

13. Rooms in which suction gas plant is installed must be of
such a height that all the plant and its connections can be
easily reached for cleaning, &c., and be capable of such free
ventilation as to render impossible an accumulation of gas.

14. These rooms must be separated from living rooms by a wall
without any openings in it. Emanations also must be prevented
as far as possible from entering into living or working rooms
situated over the gas engine.

15. Erection of apparatus for generating and purifying suction
gas in cellars shall only be allowed if specially effective
ventilation is provided by natural or mechanical means.

Other Regulations are those of the Prussian Ministerial Decree, dated June 20, 1904, as to the arrangement and management of suction gas premises.

ACETYLENE GAS INSTALLATIONS

(See also pp. 85-7)

The following regulations for the protection of workers in acetylene gas installations are taken from the Prussian Ministerial Decree, dated 2 November, 1897:

1. Preparation and condensation of acetylene on the one hand,
and liquefaction on the other, must be carried on in separate
buildings.

2. If the pressure employed for condensation of the gas exceeds
eight atmospheres, this work must take place in a room set
apart for the purpose.

3. Rooms in which acetylene is prepared, condensed, or
liquefied shall not be used as, nor be in direct connection
with, living rooms. They must be well lighted and ventilated.

4. The carbide must be kept in closed watertight vessels, so
as to ensure perfect dryness and only such quantities shall
be taken out as are needed. The vessels must be kept in dry,
light, well-ventilated rooms; cellar rooms may not be used for
storage purposes.

5. Crushing of carbide must be done with the greatest possible
avoidance of dust. Workers are to be provided with respirators
and goggles.

6. Acetylene gasometers must be fitted up in the open air or in
a well-ventilated room, separated from the gas generator. Every
gas receiver must have a water gauge showing the pressure in
the receiver.

7. Between the gasometer and receiver a gas purifier must be
provided so as to remove impurities (phosphoretted hydrogen,
arseniuretted hydrogen, carbon bisulphide, ammonia, &c.).

8. Condensation of acetylene gas at a pressure exceeding ten
atmospheres shall only be done in combination with cooling.

DISTRIBUTION AND USE OF POWER AND ILLUMINATING GAS

The Austrian Gas Regulations (of July 18, 1906) contain general provisions as to impermeability and security of the gas pipes and the precautions to be observed in their installation. Special directions follow as to main flues, material, dimensions, branches, and connections, valve arrangements, testing of the pipes against leakage, directions for discovering leaks, and other defects; also the nature of the branch pipes (dimensions and material), valves, cocks, syphons, water seals, and pressure gauges. In addition there are directions as to testing pipes and how to deal with escape of gas, freezing of pipes, and other mishaps.

Ammonia

(See also pp. 90-3 and 175)

In the production of ammonia and ammonium salts (ammonium sulphate) combination of the ammoniacal vapour with the sulphuric acid is accompanied with the formation of volatile dangerous gases containing sulphuretted hydrogen and cyanogen compounds, which produce marked oppression and sometimes endanger the health of the workers. Drawing-off these fumes into the furnace (practised sometimes in small industries) is not advisable, as the sulphuretted hydrogen is burnt to sulphur dioxide; if it is burnt absorption of the sulphur dioxide should follow, or working it up into sulphuric acid (Leymann). Often these gases are freed from cyanogen compounds and sulphuretted hydrogen by means of gas purifying materials, such as are used in gas works. The whole apparatus must be impervious. Where liquids containing ammonia are used exhaust ventilation is necessary.

Cyanogen, Cyanogen Compounds

(See also pp. 93-5 and 195-7)

Processes in which cyanogen gas can develop, require to be done under a powerful exhaust draught.

In the production of cyanogen compounds possibility of the escape of hydrocyanic acid (prussic acid) has to be borne in mind. Such escape is possible in its production from raw animal products.

The most careful cleanliness and observance of general measures for personal hygiene are necessary in factories in which cyanogen compounds are manufactured or handled. In crushing cyanide of potassium the workers should wear indiarubber gloves and respirators. The products should be stored in closed vessels in dry store rooms set apart for the purpose.

Modern cyanide of potassium factories which work up molasses, from which the sugar has been removed, and also residuary distillery liquors, so far conform with hygienic requirements that all the apparatus is under negative pressure, so that poisonous gases cannot escape into the workrooms.

Coal Tar, Tar Products

(See also pp. 96-119)

Care must be taken for the removal of injurious gases developed in the manipulation and use of tar (tar distillation) and in the processes of cleaning connected therewith. This can be most effectively done by carrying on the processes in closed apparatus. Hofmann describes such a factory where all mixing vessels in which the distillation products are further treated are completely closed in, so that even in mixing and running off, no contact is possible with the material.

The vessels for holding tar, tar-water, &c., must be impervious and kept covered. Only the cold pitch and asphalt should be stored in open pits. The cooling of the distillation products and residues, so long as they give off poisonous and strongly-smelling fumes, should be carried out in metal or bricked receivers. Such directions find a place in the ‘Technical Instructions’ appended to the German Factory Code. Without doubt, tar is, because of its smell and for other reasons, unpleasant to handle, and the danger to health from contact with it is not a matter of indifference. Spilling of small quantities of tar during transport and other manipulations can hardly be avoided. Careful cleanliness, therefore, on the part of workers is strongly urged. It may be mentioned that if tar is covered with a layer of tar-water, treatment with acid fluids develops sulphur and cyanogen compounds, which may affect the workers. Tar water should, therefore, be separated carefully from the tar and used for the preparation of ammonia.

The same remarks as to cleanliness, &c., apply in the manufacture of felt, lamp-black, and briquettes, with use of tar. Saturation of felt, and manufacture of tar plaster should be done in closed apparatus. In the production of lamp-black, even with a great number of soot chambers, there is escape of soot causing nuisance to workers and the neighbourhood. Complete avoidance of this seems to be difficult, so that measures for personal hygiene must be assured. In briquette factories it has been found useful to heat the tar by means of steam instead of by direct fire, which renders possible the use of a closed apparatus and mechanical stirring.

In the distillation of tar, during the first distillation period (first runnings) unpleasant and injurious gases containing ammonia and sulphur escape from the stills. These should (according to Leymann) be carried away through closed pipes branching off from the lower end of the running-off pipe, either into the furnace (in doing which a possible back flash of flame is to be guarded against) or be subjected to purification by lime or oxide of iron (similar to that in the case of illuminating gas) with a view to recovery of ammonia and sulphur. The lower end of the distillation pipes should be U-shaped so as to form a liquid seal—the pipes for the drawing off of the gases branching off before the curve. In the later stages of distillation risk can be checked by careful cooling and imperviousness of the apparatus.

Very unpleasant yellow fumes develop in great quantity when pitch is run off from the hot still. Hence hot pitch should not be run off into open pitch receptacles, but be cooled first in closed receptacles.

The crude products obtained by distillation (light oil, creosote oil) are subjected to purification consisting in treatment on the one hand with alkali and on the other with acid and followed by fractional distillation. In these processes injurious fumes may develop, therefore they must—as already mentioned—be carried on in closed vessels provided with means of escape for fumes and appliances for mechanical stirring; the fumes drawn off must be led into the chimney stack.

In the distillation of brown coal, of tar, and of resin, it is necessary, as in the distillation of coal tar, to insist above all on careful cooling and condensation, and thorough absorption of uncondensed gases in washing towers. Special precautionary rules are necessary to guard against the danger of entering tar stills for cleaning purposes. Such directions were approved in Great Britain in 1904 in view of accidents which occurred in this way:

TAR DISTILLING

The following directions[I] are approved by the Home Office
and are applicable to factories in which is carried on the
distillation of tar for the production of naphtha, light oil,
creosote oil, and pitch.