Fig. 10.—Preparation of Nitro-glycerin. Nitrating Vessel (after Guttmann)
A Glycerine reservoir; C Fume flue; D Acid supply pipe; E, G Compressed air supply; H, J Cooling coil.
A fatal case in a nitro-glycerin factory was reported in 1902 where, through carelessness, a separator had overflowed. The workman who tried to wash away the acid with water inhaled so much of the nitrous fumes that he succumbed sixteen hours later.
Other cases of poisoning by nitrous fumes occurring in the denitrating department are described in detail in the section on the use of nitric acid.
One of these occurred to a man forcing dilute nitric acid from an earthenware egg by means of compressed air into a washing tower. The egg burst and broke an acid tank. The workman died on the following day.
A fatal case occurred in a dynamite factory in cleaning out a storage tank for waste acid in spite of previous swilling and ventilation.
Gun cotton (pyroxyline) and its use.—Pyroxyline is the collective name for all products of the action of nitric acid on cellulose (cotton wool and similar material); these products form nitric acid ester of cellulose (nitro-cellulose).
Gun cotton is formed by the action of strong nitric acid on cellulose (cotton wool). A mixture of sulphuric and nitric acids is allowed to act on cotton wool (previously freed from grease, purified, and dried), with subsequent pressing and centrifugalising. In the nitrating centrifugal machine (in the Selvig-Lange method) both processes are effected at the same time.
The interior of this apparatus is filled with nitric acid, cotton wool is introduced, the acid fumes exhausted through earthenware pipes, and the remainder of the acid removed by the centrifugal machine; the nitrated material is then washed, teazed in teazing machines, again washed, neutralised with calcium carbonate, again centrifugalised, and dried. Since drying in drying stoves is a great source of danger of explosion, dehydration is effected with alcohol, and the gun cotton intended for the production of smokeless powder carried directly to the gelatinising vessels (see Smokeless Powder).
Gun cotton, apart from its use for smokeless powder, is pressed in prisms and used for charging torpedoes and sea mines.
Collodion cotton is a partially nitrated cellulose. It is prepared generally in the same way as gun cotton, except that it is treated with a more dilute acid. It is soluble (in contradistinction to gun cotton) in alcohol-ether, and the solution is known as collodion (as used in surgery, photography, and to impregnate incandescent gas mantles). Mixed with camphor and heated collodion forms celluloid.
In Chardonnet’s method for making artificial silk collodion is used by forcing it through fine glass tubes and drawing and spinning it. The alcohol-ether vapours are carried away by fans and the spun material is de-nitrated by ammonium sulphide.
Smokeless powder is a gun cotton powder—that is gun cotton the explosive power of which is utilised by bringing it into a gelatinous condition. This is effected by gelatinising the gun cotton with alcohol-ether or acetone (sometimes with addition of camphor, resin, &c.). A doughy, pasty mass results, which is then rolled, washed, dried, and pressed into rods. Nobel’s nitroleum (artillery powder) consists half of nitro-glycerin and half of collodion cotton. In the production of gun cotton and collodion cotton the workers are affected and endangered by nitric and nitrous fumes unless the nitrating apparatus is completely airtight.
Erosion of the incisor teeth is general, but use of the new nitrating apparatus, especially of the nitrating centrifugal machines already described, has greatly diminished the evil. In making collodion, celluloid and artificial silk, in addition to the risks referred to in the production of gun cotton, the vapour from the solvents, ether, alcohol, acetone, acetic-ether, and camphor, comes into consideration, but there is no account of such poisoning in the literature of the subject.
Other explosives which belong to the aromatic series are described in the chapter on Tar Derivatives, especially picric acid.
The total production of phosphorus is not large. Formerly it was prepared from bone ash. Now it is made from phosphorite, which, as in the super-phosphate industry, is decomposed by means of sulphuric acid, soluble phosphate and calcium sulphate being formed; the latter is removed, the solution evaporated, mixed with coal or coke powder, distilled in clay retorts, and received in water.
Phosphorus is also obtained electro-chemically from a mixture of tricalcium phosphate, carbon, and silicic acid, re-distilled for further purification, and finally poured under water into stick form.
Red phosphorus (amorphous phosphorus) is obtained by heating yellow phosphorus in the absence of air and subsequently extracting with carbon bisulphide.
Phosphorus matches are made by first fixing the wooden splints in frames and then dipping the ends either into paraffin or sulphur which serve to carry the flame to the wood. Then follows dipping in the phosphorus paste proper, for which suitable dipping machines are now used. The phosphorus paste consists of yellow phosphorus, an oxidising agent (red lead, lead nitrate, nitre, or manganese dioxide) and a binding substance (dextrine, gum); finally the matches are dried and packed.
Safety matches are made in the same way, except that there is no phosphorus. The paste consists of potassium chlorate, sulphur, or antimony sulphide, potassium bichromate, solution of gum or dextrine, and different admixtures such as glass powder, &c. These matches are saturated with paraffin or ammonium phosphate. To strike them a special friction surface is required containing red phosphorus, antimony sulphide, and dextrine. In the act of striking the heat generated converts a trace of the red phosphorus into the yellow variety which takes fire.
Danger to health arises from the poisonous gases evolved in the decomposition of the calcined bones by sulphuric acid. When phosphorus is made from phosphorite the same dangers to health are present as in the production of super-phosphate artificial manure, which is characterised by the generation of hydrofluoric and fluosilicic acids. In the distillation of phosphorus phosphoretted hydrogen and phosphorus fumes may escape and prove dangerous.
Industrial poisoning from the use of white phosphorus in the manufacture of matches has greater interest than its occurrence in the production of phosphorus itself. Already in 1845 chronic phosphorus poisoning (phosphorus necrosis) had been observed by Lorinser, and carefully described by Bibra and Geist in 1847. In the early years of its use phosphorus necrosis must have been fairly frequent in lucifer match factories, and not infrequently have led to death. This necessitated preventive measures in various States (see Part III); cases became fewer, but did not disappear altogether.
Especially dangerous is the preparation of the paste, dipping, and manipulations connected with drying and filling the matches into boxes. According to the reports of the Austrian factory inspectors there are about 4500 lucifer match workers in that country, among whom seventy-four cases of necrosis are known to have occurred between the years 1900 and 1908 inclusive.
Teleky1 considers these figures much too small, and from inquiries undertaken himself ascertained that 156 cases occurred in Austria between 1896 and 1906, while factory inspectors’ reports dealt with only seventy-five. He was of opinion that his own figures were not complete, and thinks that in the ten years 1896 to 1905 there must have been from 350 to 400 cases of phosphorus necrosis in the whole of Austria. Despite strict regulations, modern equipment of the factories, introduction of improved machinery, and limitation of the white phosphorus match industry to large factories, it has not been possible to banish the risk, and the same is true of Bohemia, where there is always a succession of cases. Valuable statistics of phosphorus necrosis in Hungary are available.2 In 1908 there were sixteen factories employing 1882 workers of whom 30 per cent. were young—children even were employed. The industry is carried on in primitive fashion without hygienic arrangements anywhere. It is strange that, notwithstanding these bad conditions, among a large number of the workers examined only fourteen active cases were found, in addition to two commencing, and fifteen cured—altogether thirty-one cases (excluding fifty-five cases in which there was some other pathological change in the mouth). Altogether ninety-three cases since 1900 were traced in Hungary, and in view of the unsatisfactory situation preventive measures, short of prohibition of the use of white phosphorus, would be useless.
In England among 4000 lucifer match workers there were thirteen cases in the years 1900 to 1907 inclusive. Diminution in the number was due to improved methods of manufacture and periodical dental examination prescribed under Special Rules.
Phosphorus necrosis is not the only sign of industrial phosphorus poisoning, as the condition of fragilitas ossium is recognised.3 From what has been said it is evident that preventive measures against phosphorus poisoning, although they diminish the number, are not able to get rid of phosphorus necrosis, and so civilised States have gradually been driven to prohibit the use of white phosphorus (for the history of this see Part III).
Use of chrome salts (especially potassium bichromate) in the preparation of the paste causes risk of poisoning in premises where ‘Swedish’ matches are made. Attention has been called to the frequency of chrome ulceration.4 The paste used consists of 3-6 per cent. chrome salt, so that each match head contains about ½ mg. Wodtke found among eighty-four workers early perforation of the septum in thirteen. Severe eczema also has been noted.
It is even alleged that red phosphorus is not entirely free from danger. Such cachexia as has been noted may be referable to the absorption of potassium chlorate.
Isolated cases of phosphorus poisoning have been observed in the manufacture of phosphor-bronze. This consists of 90 parts copper, 9 parts tin, and 0·5 to 0·75 phosphorus.
Sulphides of phosphorus (P₂S₅, P₄S₃, P₂S₃) are made by melting together red phosphorus and sulphur. They make a satisfactory substitute for the poisonous yellow phosphorus and are considered non-poisonous, but the fact remains that they give off annoying sulphuretted hydrogen gas.
Phosphoretted hydrogen gas (PH₃) rarely gives rise to industrial poisoning. It may come off in small amounts in the preparation of acetylene and in the preparation of, and manipulations with, white phosphorus. It is stated that in acetylene made of American calcium carbide 0·04 per cent. of phosphoretted hydrogen is present, and in acetylene from Swedish calcium carbide 0·02 per cent.; Lunge and Cederkreutz found an acetylene containing 0·06 per cent. These amounts might cause poisoning if the gas were diffused in confined spaces. Poisoning, in part attributable to phosphoretted hydrogen gas, is brought about through ferro-silicon (see under Ferro-silicon).
Superphosphate, an artificial manure, is prepared from various raw materials having a high proportion of insoluble basic calcium phosphate (tricalcium phosphate), which by treatment with sulphuric acid are converted into the soluble acid calcium phosphate (monocalcium phosphate) and calcium sulphate. Mineral substances such as phosphorites, coprolites, guano, bone ash, &c., serve as the starting-point. Chamber acid, or sometimes the waste acid from the preparation of nitro-benzene or purification of petroleum, are used in the conversion. The raw materials are ground in closed-in apparatus, under negative pressure, and mixed with the sulphuric acid in wooden lead-lined boxes or walled receptacles. The product is then stored until the completion of the reaction in ‘dens,’ dried, and pulverised in disintegrators.
In the manufacture of bone meal extraction of the fat from the bones with benzine precedes treatment with acid.
A further source of artificial manure is basic slag—the slag left in the manufacture of steel by the Gilchrist-Thomas method—which contains 10-25 per cent. of readily soluble phosphoric acid. It requires, therefore, only to be ground into a very fine powder to serve as a suitable manure.
Owing to the considerable heat generated by the action of the sulphuric acid when mixed with the pulverised raw materials (especially in the conversion of the phosphorites) hydrofluoric and silicofluoric acid vapours are evolved in appreciable amount, and also carbonic and hydrochloric acid vapours, sulphur dioxide, and sulphuretted hydrogen gas. These gases—notably such as contain fluorine—if not effectually dealt with by air-tight apparatus and exhaust ventilation—may lead to serious annoyance and injury to the persons employed. Further, there is risk of erosion of the skin from contact with the acid, &c.
A case is described of pustular eczema on the scrotum of a worker engaged in drying sodium silicofluoride, due probably to conveyance of irritating matter by the hands. After the precaution of wearing gloves was adopted the affection disappeared.
A marked case of poisoning by nitrous fumes even is recorded in the manufacture of artificial manure from mixing Chili saltpetre with a very acid superphosphate.
Injurious fumes can be given off in the rooms where bones are stored and, in the absence of efficient ventilation, carbonic acid gas can accumulate to an amount that may be dangerous.
The fine dust produced in the grinding of basic slag has, if inhaled, a markedly corrosive action on the respiratory mucous membrane attributed by some to the high proportion (about 50 per cent.) in it of quicklime. As a matter of fact numerous small ulcers are found on the mucous membranes of basic slag grinders and ulceration of the lung tissue has been observed. The opinion is expressed that this is due to corrosive action of the dust itself, and not merely to the sharp, jagged edged particles of dust inhaled. And in support of this view is cited the frequency with which epidemics of pneumonia have been noted among persons employed in basic slag works. Thus in Nantes thirteen cases of severe pneumonia followed one another in quick succession. And similar association has been noted in Middlesbrough, where the action of the basic slag dust was believed to injure the lung tissue and therefore to provide a favourable soil for the development of the pneumonia bacillus. Statistics collected by the Imperial Health Office showed that in the three years 1892, 1893, and 1894, 91·1 per cent., 108·9 per cent., and 91·3 per cent. respectively of the workers became ill, the proportion of respiratory diseases being 56·4 per cent., 54·4 per cent., and 54·3 per cent. respectively. A case of severe inflammation of the lungs is described in a labourer scattering basic slag in a high wind which drove some of it back in his face.
Lewin has described a case in which a worker scattering a mixture of basic slag and ammonium superphosphate suffered from an eczematous ulceration which, on being scratched by the patient, became infected and led to death from general blood poisoning. Lewin regarded the fatal issue as the sequela of the scattering of the manure.
Inflammation of the conjunctiva and of the eyelids has been recorded.
Chrome ironstone, lime, and soda are ground and intimately mixed. They are next roasted in reverberatory furnaces, neutral sodium chromate being formed. This is lixiviated and converted into sodium bichromate (Na₂Cr₂O₇) by treatment with sulphuric acid. Concentration by evaporation follows; the concentrated liquor is crystallised in cast-iron tanks. The crystals are centrifugalised, dried, and packed. Potassium bichromate may be made in the same way, or, as is usually the case, out of sodium bichromate and potassium chloride.
The bichromates are used in the preparation and oxidation of chrome colours, but their principal use is in dyeing and calico printing, bleaching palm oil, purifying wood spirit and brandy, in the preparation of ‘Swedish’ matches, in the manufacture of glass, in photography, in dyeing, in tanning, and in oxidation of anthracene to anthraquinone.
Chrome yellow is neutral lead chromate (PbCrO₄). It is obtained by precipitating a solution of potassium bichromate with lead acetate or lead nitrate, or by digesting the bichromate solution with lead sulphate, and is used as a paint and in calico and cloth printing. With Paris or Berlin blue it forms a chrome green. Chrome orange, i.e. basic lead chromate (PbCrO₄Pb(OH)₂) is made by adding milk of lime to lead chromate and boiling.
Chromium and chromic acid salts are widely used in dyeing and printing, both as mordants and oxidising agents and as dyes (chrome yellow, chrome orange). In mordanting wool with potassium chromate the wool is boiled in a potassium chromate solution to which acids such as sulphuric, lactic, oxalic, or acetic are added.
In dyeing with chrome yellow, for instance, the following is the process. Cotton wool is saturated with nitrate or acetate of lead and dried, passed through lime water, ammonia, or sodium sulphate, and soaked in a warm solution of potassium bichromate. The yellow is converted into the orange colour by subsequent passage through milk of lime.
Chrome tanning.—This method of producing chrome leather, first patented in America, is carried out by either the single or two bath process.
In the two bath process the material is first soaked in a saturated solution of bichromate and then treated with an acid solution of thiosulphate (sodium hyposulphite) so as to reduce completely the chromic acid. The process is completed even with the hardest skins in from two to three days.
In the single bath method basic chrome salts are used in highly concentrated form. The skins are passed from dilute into strong solutions. In this process also tanning is quickly effected.
Effects on Health.—Among the persons employed in the bichromate factory of which Leymann has furnished detailed particulars, the number of sick days was greater than that among other workers.
Further, erosion of the skin (chrome holes) is characteristic of the manufacture of bichromates. These are sluggish ulcers taking a long time to heal. This is the main cause of the increased general morbidity that has been observed. The well-known perforation of the septum of the nose without, however, causing ulterior effects, was observed by Leymann in all the workers in the factory. This coincides with the opinion of others who have found the occurrence of chrome holes, and especially perforation of the septum, as an extraordinarily frequent occurrence. Many such observations are recorded,1 and also in workers manufacturing ‘Swedish’ matches. Thus of 237 bichromate workers, ulcers were present in 107 and perforation in 87. According to Lewin, who has paid special attention to the poisonous nature of chromium compounds, they can act in two ways: first, on the skin and mucous membrane, where the dust alights, on the alimentary tract by swallowing, and on the pharynx by inhalation. Secondly, by absorption into the blood, kidney disease may result.
The opinion that chromium, in addition to local, can have constitutional effect is supported by other authorities. Leymann describes a case of severe industrial chrome poisoning accompanied by nephritis in a worker who had inhaled and swallowed much chromate dust in cleaning out a vessel. Regulations for the manufacture of bichromates (see Part III) have no doubt improved the condition, but reports still show that perforation of the septum generally takes place.
It must be borne in mind that practically all chromium compounds are not alike poisonous. Chrome ironstone is non-poisonous, and the potassium and sodium salts are by far the most poisonous, while the neutral chromate salts and chromic oxide are only slightly so. Pander found that bichromates were 100 times as poisonous as the soluble chromium oxide compounds, and Kunkel is of opinion that poisonous effect shown by the oxides is attributable to traces of oxidation into chromic acid.
Lewin, on the other hand, declares in a cautionary notice for chrome workers generally that all chromium compounds are poisonous, and therefore all the dyes made from them.2
In the manufacture of bichromates, chance of injury to health arises partly from the dust, and partly from the steam, generated in pouring water over the molten mass. The steam carries particles of chromium compounds with it into the air. In evaporating the chromate solutions, preparation of the bichromate, breaking the crystals, drying and packing, the workers come into contact with the substance and the liquors. Chrome ulceration is, therefore, most frequently found among those employed in the crystal room and less among the furnace hands.
From 3·30 to 6·30 mg. of bichromate dust have been found in 1 c.m. of air at breathing level in the room where chromate was crushed, and 1·57 mg. where it was packed. Further, presence of chromium in the steam escaping from the hot chrome liquors has been proved.3
Poisoning from use of chrome colours is partly attributable to lead, as, for example, in making yellow coloured tape measures, yellow stamps, and from the use of coloured thread. Gazaneuve4 found 10 per cent. of lead chromate in such thread, in wool 18 per cent., and in the dust of rooms where such yarn was worked up 44 per cent.
Use of chrome colours and mordants is accompanied by illness which certainly is referable to the poisonous nature of the chrome. In France use of chromic and phosphoric acid in etching zinc plates has caused severe ulceration.
Bichromate poisoning has been described among photographers in Edinburgh in the process of carbon printing, in which a bichromate developer is used.5
There is much evidence as to occurrence of skin eruptions and development of pustular eczema of the hands and forearms of workers in chrome tanneries.6 In a large leather factory where 300 workers were constantly employed in chrome tanning nineteen cases of chrome ulceration were noted within a year. Injury to health was noted in a chrome tannery in the district of Treves, where the two bath process was used, from steam developed in dissolving the chromate in hot water.
Finally, I have found several records in 1907 and 1908 of perforation of the septum in Bohemian glass workers.
The raw material of the manganese industry is hausmannite (manganese dioxide, MnO₂). This is subjected to a crushing process, sorted, sieved, finely ground, washed, and dried. The pure finely ground manganese dioxide is much used in the chemical industry, especially in the recovery of chlorine in the Weldon process and in the production of potassium permanganate, which is obtained by melting manganese dioxide with caustic soda and potassium chlorate or nitre, lixiviation and introduction of carbonic acid, or better by treatment with ozone.
Manganese is also used in the production of colours: the natural and artificial umbers contain it; in glass works it is used to decolourise glass, and also in the production of coloured glass and glazes; in the manufacture of stove tiles, and in the production of driers for the varnish and oil industry. Manganese and compounds of manganese are dangerous when absorbed into the system as dust.
Already in 1837 nervous disorders had been described in workmen who ground manganese dioxide.1 The malady was forgotten, until Jaksch2 in Prague in 1901 demonstrated several such cases in persons employed in a large chemical factory in Bohemia, from the drying of Weldon mud. In the same year three similar cases were also described in Hamburg.3 In 1902 Jaksch observed a fresh case of poisoning, and in the factory in question described a condition of manganophobia among the workers, obviously hysterical, in which symptoms of real manganese poisoning were simulated. In all some twenty cases are known. Jaksch is of opinion that it is manganese dust rich in manganese protoxide that is alone dangerous, since, if the mud has been previously treated with hydrochloric acid, by which the lower oxides are removed, no illness can be found. The most dangerous compounds are MnO and Mn₃O₄.
Occurrence and Uses.—Crude petroleum flows spontaneously from wells in consequence of high internal pressure of gas or is pumped up. In America and Russia also it is conveyed hundreds of miles in conduits to the ports to be led into tank steamers.
The crude oil is a dark-coloured liquid which, in the case of Pennsylvanian mineral oil, consists mainly of a mixture of hydrocarbons of the paraffin series, or, in Baku oil, of those of the naphtha series. There are in addition sulphur compounds, olefines, pyridin, &c. The crude oil is unsuitable for illuminating purposes and is subjected to a distillation process. It is split up into three fractions by a single distillation, namely, (a) benzines (boiling-point 150° C.), (b) lighting oil (boiling-point 150°-300° C.); at a temperature of 300° C. the distillation is stopped so that (c) the residuum boiling above 300° C. remains. Distillation is effected (in America) in large stills, in which periodically benzine and lighting oil up to 300° C. is distilled and the residuum run off. In Baku continuously working batteries of so-called cylindrical boilers are used, into which the crude oil streams. In the first set of boilers, the temperature in which rises to 150° C., the benzine is distilled off, and in the succeeding ones, heated to 300° C., the illuminating petroleum oils (kerosine), the residuum flowing continually away.
The mineral oil residues are used as fuel. Heating by this means, tried first only in Russia, is spreading, especially for the heating of boilers, in which case the liquid fuel is blown in generally as a spray. The combustion if rightly planned is economical and almost smokeless.
The American oil residuum, rich in paraffin, is distilled, the distillate is cooled and separated by pressure into solid paraffin and liquid oil. The latter and the Russian mineral oil residues which are free from paraffin are widely used as lubricants. In the production of lubricants the residues are distilled at low temperature (in vacuo or by aid of superheated steam) and separated into various qualities by fractional cooling, are then purified with sulphuric acid, and finally washed with caustic soda solution.
In the preparation of vaseline the residum is not distilled, but purified only with fuming sulphuric acid and decolourised with animal charcoal.
The illuminating oil is next subjected to a purifying process (refining); it is first treated with sulphuric acid and well agitated by means of compressed air. The acid laden with the impurities is drawn off below, and the oil freed from acid by washing first with caustic soda and subsequently with water. It is then bleached in the sun. For specially fine and high flash point petroleum the oil undergoes a further distillation and purification with acid.
The fractions of crude petroleum with low boiling-point (under 150° C.) are known commercially as raw benzine or petrol naphtha. It is used for cleaning, in extraction of fats and oils, and for benzine motors.
Frequently raw benzine is subjected to a purifying process and to fractional distillation. Purification is carried out by means of sulphuric acid and soda liquor and subsequent separation into three fractions and a residue which remains in the retort—(a) petroleum ether (called gasoline, canadol, and rhigoline), which comes over between 40° and 70° C., and serves for carburetting water gas and other similar gases, as a solvent for resin, oil, rubber, &c.; (b) purified benzine (70°-120° C.) is used as motor spirit and in chemical cleaning; (c) ligroine (120°-135° C.), used for illuminating purposes; and (d) the residual oil (above 135° C.) serves for cleaning machinery and, especially, as a solvent for lubricating oil, and instead of turpentine in the production of lacquers, varnishes, and oil colours.
In chemical cleaning works benzine is used in closed-in washing apparatus, after which the clothes are centrifugalised and dried. In view of the risk of fire in these manipulations, originating mainly from frictional electricity, various substances are recommended to be added to the benzine, of which the best known is that recommended by Richter, consisting of a watery solution of oleate of sodium or magnesium.
Effects on Health.—Industrial poisoning in the petroleum industry is attributable to the gases given off from crude petroleum or its products and to inhalation of naphtha dust. Poisoning occurs principally in the recovery of petroleum and naphtha from the wells, in storage and transport (in badly ventilated tanks on board ship, and in entering petroleum tanks), in the refinery in cleaning out petroleum stills and mixing vessels, and in emptying out the residues. Further cases occur occasionally from use of benzine in chemical cleaning.
In addition to poisoning the injurious effect of petroleum and its constituents on the skin must be borne in mind. Opinion is unanimous that this injurious action of mineral oil is limited to the petroleum fractions with high boiling-point and especially petroleum residues.
Statistics officially collected in Prussia show the general health of petroleum workers to be favourable. These statistics related to 1380 persons, of whom forty-three were suffering from symptoms attributable to their occupation. Of these forty-three, nine only were cases of poisoning, the remainder being all cases of petroleum acne.
The conditions also in French refineries from statistics collected in the years 1890-1903 seem satisfactory. Eighteen cases of petroleum acne were reported, eleven of which occurred at the paraffin presses, five in cleaning out the still residues, and two were persons filling vessels.
The conditions are clearly less favourable in the Russian petroleum industry.1
The workers at the naphtha wells suffer from acute and chronic affections of the respiratory organs. Those suffer most who cover the wells with cast iron plates to enable the flow of naphtha to be regulated and led into the reservoirs. In doing this they inhale naphtha spray.
Lewin2 describes cases of severe poisoning with fatal issue among American workers employed in petroleum tanks. One man who wished to examine an outlet pipe showed symptoms after only two minutes. Weinberger describes severe poisoning of two workers engaged in cleaning out a vessel containing petroleum residue.
Interesting particulars are given of the effect of petroleum emanations on the health of the men employed in the petroleum mines of Carpathia, among whom respiratory affections were rarely found, but poisoning symptoms involving unconsciousness and cerebral symptoms frequently. These experiences undoubtedly point to differing physiological effects of different kinds of naphtha.
This is supported by the view expressed by Sharp in America that different kinds of American petroleum have different effects on the health of the workers, which can be easily credited from the different chemical composition of crude naphthas. Thus in Western Virginia, where a natural heavy oil is obtained, asphyxia from the gas is unknown, although transient attacks of headache and giddiness may occur, whereas in Ohio, where light oils are obtained, suffocative attacks are not infrequent. And it is definitely stated that some naphtha products irritate the respiratory passages, while others affect the central nervous system.3
The authors mentioned refer to occurrence of cases of poisoning in the refining of naphtha from inhalation of the vapour of the light oils benzine and gasoline. Fatal cases have been recorded in badly ventilated workrooms in which the products of distillation are collected. Workers constantly employed in these rooms develop chronic poisoning, which is reported also in the case of women employed with benzine. Intoxication is frequently observed, it is stated, among the workmen employed in cleaning out the railway tank waggons in which the mineral oils and petroleum are carried.
Foulerton4 describes severe poisoning in a workman who had climbed into a petroleum reservoir, and two similar cases from entering naphtha tanks are given in the Report of the Chief Inspector of Factories for 1908. Two fatal cases are reported by the Union of Chemical Industry in Germany in 1905 in connection with naphtha stills. Such accidents are hardly possible, except when, through insufficient disconnection of the still from the further system of pipes, irrespirable distillation gases pass backwards into the opened still where persons are working. Ordinary cocks and valves, therefore, do not afford sufficient security. Thus, several workers engaged in repairing a still were rendered unconscious by gases drawn in from a neighbouring still, and were only brought round after oxygen inhalation.
Gowers describes a case of chronic poisoning following on frequent inhalation of gases given off from a petroleum motor, the symptoms being slurring speech, difficulty of swallowing, and weakness of the orbicularis and facial muscles. Gowers believed this to be petroleum gas poisoning (from incomplete combustion), especially as the symptoms disappeared on giving up the work, only to return on resuming it again.5
Girls employed in glove cleaning and rubber factories are described as having been poisoned by benzine.6 Poisoning of chauffeurs is described by several writers.7
Recent literature8 tends to show marked increase in the number of cases of poisoning from greater demand for benzine as a motive power for vehicles. Such cases have been observed in automobile factories, and are attributable to the hydrocarbons of low boiling-point which are present as impurities in benzine.
A worker in a paraffin factory had entered an open benzine still to scrape the walls free of crusts containing benzine. He was found unconscious and died some hours later. It appeared that he had been in the still several hours, having probably been overcome to such an extent by the fumes as to be unable to effect his escape.
Attempt to wipe up benzine spilt in the storage cellar of a large chemical cleaning works resulted in poisoning.
A night worker in a bone extracting works having turned on the steam, instead of watching the process fell asleep on a bench. In consequence the apparatus became so hot that the solder of a stop valve melted, allowing fumes to escape. The man was found dead in the morning. In a carpet cleaning establishment three workers lost consciousness and were found senseless on the floor. They recovered on inhalation of oxygen.
One further case reported from the instances of benzine poisoning collected recently9 is worth quoting. A worker in a chemical factory was put to clean a still capable of distilling 2500 litres of benzine. It contained remains of a previous filling. As soon as he had entered the narrow opening he became affected and fell into the benzine; he was carried unconscious to the hospital, his symptoms being vomiting, spastic contraction of the extremities, cyanosis, weak pulse, and loss of reflexes, which disappeared an hour and a half later.
The occurrence of skin affections in the naphtha industry has been noted by several observers, especially among those employed on the unpurified mineral oils. Eruptions on the skin from pressing out the paraffin and papillomata (warty growths) in workers cleaning out the stills are referred to by many writers,10 Ogston in particular.
Recent literature refers to the occurrence of petroleum eczema in a firebrick and cement factory. The workers affected had to remove the bricks from moulds on to which petroleum oil dropped. An eczematous condition was produced on the inner surface of the hands, necessitating abstention from work. The pustular eczema in those employed only a short time in pressing paraffin in the refineries of naphtha factories is referred to as a frequent occurrence. Practically all the workers in three refineries in the district of Czernowitz were affected. The view that it is due to insufficient care in washing is supported by the report of the factory inspector in Rouen, that with greater attention in this matter on the part of the workers marked diminution in its occurrence followed.
Recovery and Use.—Sulphur, which is found principally in Sicily (also in Spain, America, and Japan), is obtained by melting. In Sicily this is carried out in primitive fashion by piling the rock in heaps, covering them with turf, and setting fire to them. About a third of the sulphur burns and escapes as sulphur dioxide, while the remainder is melted and collects in a hole in the ground.
The crude sulphur thus wastefully produced is purified by distillation in cast-iron retorts directly fired. It comes on the market as stick or roll sulphur or as flowers of sulphur.
Further sources for recovery of sulphur are the Leblanc soda residues (see Soda Production), from which the sulphur is recovered by the Chance-Claus process, and the gas purifying material (containing up to 40 per cent.), from which the sulphur can be recovered by carbon bisulphide (see Illuminating Gas Industry).
The health conditions of the Sicilian sulphur workers are very unsatisfactory, due, however, less to the injurious effect of the escaping gases (noxious alike to the surrounding vegetation) than to the wretched social conditions, over exertion, and under feeding of these workers.
Of importance is the risk to health from sulphuretted hydrogen gas, from sulphur dioxide in the recovery of sulphur from the soda residues, and from carbon bisulphide in the extraction of sulphur from the gas purifying material.
Sulphuretted hydrogen gas is used in the chemical industry especially for the precipitation of copper in the nickel and cobalt industry, in de-arsenicating acid (see Hydrochloric and Sulphuric Acids), to reduce chrome salts in the leather industry, &c. In addition it arises as a product of decomposition in various industries, such as the Leblanc soda process, in the preparation of chloride of antimony, in the decomposition of barium sulphide (by exposure to moist air), in the treatment of gas liquors, and in the preparation of carbon bisulphide: it is present in blast furnace gas, is generated in mines (especially in deep seams containing pyrites), arises in tar distillation, from use of gas lime in tanning, and in the preparation and use of sodium sulphide: large quantities of the gas are generated in the putrefactive processes connected with organic sulphur-containing matter such as glue making, bone stores, storage of green hides, in the decomposition of waste water in sugar manufacture and brewing, in the retting of flax, and especially in sewers and middens.
Both acute and chronic poisoning are described.
The following case is reported by the Union of Chemical Industry in 1907: Three plumbers who were employed on the night shift in a chemical factory and had gone to sleep in a workroom were found in a dying condition two hours later. In the factory barium sulphide solution in a series of large saturating vessels was being converted into barium carbonate by forcing in carbonic acid gas; the sulphuretted hydrogen gas evolved was collected in a gasometer, burnt, and utilised for manufacture of sulphuric acid. In the saturating vessels were test cocks, the smell from which enabled the workers to know whether all the sulphuretted hydrogen gas had been driven out. If this was so the contents of the retort were driven by means of carbonic acid gas into a subsidiary vessel, and the vessel again filled with barium sulphide liquor. From these intermediate vessels the baryta was pumped into filter presses, the last remains of sulphuretted hydrogen gas being carried away by a fan into a ventilating shaft. The subsidiary vessel and ventilating shaft were situated in front of the windows of the repairing shop. On the night in question a worker had thoughtlessly driven the contents out of one saturating vessel before the sulphuretted hydrogen gas had been completely removed, and the driving belt of the fan was broken. Consequently, the sulphuretted hydrogen gas escaping from the subsidiary vessel entered through the windows of the workshop and collected over the floor where the victims of the unusual combination of circumstances slept.
In another chemical works two workers suffered from severe poisoning in the barium chloride department. The plant consisted of a closed vat which, in addition to the openings for admitting the barium sulphide liquor and sulphuric acid, had a duct with steam injector connected with the chimney for taking away the sulphuretted hydrogen gas. Owing to a breakdown the plant was at a standstill, as a result of which the ventilating duct became blocked by ice. When the plant was set in motion again the sulphuretted hydrogen gas escaped through the sulphuric acid opening. One of the workers affected remained for two days unconscious.1
The report of the Union of Chemical Industry for 1905 cites a case where an agitating vessel, in which, by action of acid on caustic liquor, sulphuretted hydrogen gas was given off and drawn away by a fan, had to be stopped to repair one of the paddles. The flow of acid and liquor was stopped, and the cover half removed. The deposit which had been precipitated had to be got rid of next in order to liberate the agitator. The upper portion of the vessel was washed out with water, and since no further evolution of sulphuretted hydrogen was possible from any manufacturing process, the work of removing the deposit was proceeded with. After several bucketfuls had been emptied the man inside became unconscious and died. The casualty was no doubt due to small nests of free caustic and acid which the spading brought into contact and subsequent developement of sulphuretted hydrogen afresh. A case is reported of sulphuretted hydrogen poisoning in a man attending to the drains in a factory tanning leather by a quick process. Here, when sulphurous acid acts on sodium sulphide, sulphuretted hydrogen is given off. In cleaning out a trap close to the discharge outlet of a tannery two persons were rendered unconscious, and the presence of sulphuretted hydrogen was shown by the blackening of the white lead paint on a house opposite and by the odour.2
In the preparation of ammonium salts Eulenberg3 cites several cases where the workers fell as though struck down, although the processes were carried on in the open air. They quickly recovered when removed from the spot.
Oliver cites the case where, in excavating soil for a dock, four men succumbed in six weeks; the water contained 12 vols. per cent. of sulphuretted hydrogen.
Not unfrequently acute poisoning symptoms result to sewer men. Probably sulphuretted hydrogen gas is not wholly responsible for them, nor for the chronic symptoms complained of by such workers (inflammation of the conjunctiva, bronchial catarrh, pallor, depression).
In the distillation processes connected with the paraffin industry fatalities have been reported.
Manufacture.—Carbon bisulphide is prepared by passing sulphur vapour over pure coal brought to a red heat in cast-iron retorts into which pieces of sulphur are introduced. The crude carbon bisulphide requires purification from sulphur, sulphuretted hydrogen, and volatile organic sulphur compounds by washing with lime water and subsequent distillation.
Use is made of it principally in the extraction of fat and oil from bones and oleaginous seeds (cocoanut, olives, &c.), for vulcanising, and as a solvent of rubber. It is used also to extract sulphur from gas purifying material and for the preparation of various chemical substances (ammonium sulphocyanide, &c.), as well as for the destruction of pests (phylloxera and rats).
Fat and oil are extracted from seeds, bones, &c., by carbon bisulphide, benzine, or ether, and, to avoid evaporation, the vessels are as airtight as possible and arranged, as a rule, for continuous working.
Vulcanisation is the rendering of rubber permanently elastic by its combination with sulphur. It is effected by means of chloride of sulphur, sulphide of barium, calcium, or antimony, and other sulphur-containing compounds, heat and pressure, or by a cold method consisting in the dipping of the formed objects in a mixture of carbon bisulphide and chloride of sulphur. The process of manufacture is briefly as follows: The raw material is first softened and washed by hot water and kneading in rolls. The washed and dried rubber is then mixed on callender rolls with various ingredients, such as zinc white, chalk, white lead, litharge, cinnabar, graphite, rubber substitutes (prepared by boiling vegetable oils, to which sulphur has been added, with chloride of sulphur). In vulcanising by aid of heat the necessary sulphur or sulphur compound is added. Vulcanisation with sulphur alone is only possible with aid of steam and mechanical pressure in various kinds of apparatus according to the nature of the article produced. In the cold vulcanisation process the previously shaped articles are dipped for a few seconds or minutes in the mixture of carbon bisulphide and chloride of sulphur and subsequently dried in warm air as quickly as possible.
In view of the poisonous nature of carbon bisulphide, benzine is much used now. In the cold method use of chloride of sulphur in benzine can replace it altogether.
Instead of benzine other solvents are available—chlorine substitution products of methane (dichlormethane, carbon tetrachloride). In other processes rubber solvents are largely used, for instance, acetone, oil of turpentine, petroleum benzine, ether, and benzene. Rubber solutions are used for waterproofing cloth and other materials.
Similar to the preparation and use of rubber is that of guttapercha. But vulcanisation is easier by the lead and zinc thiosulphate process than by the methods used in the case of rubber.
Effects on Health of CS₂ and Other Dangers to Health in the Rubber Industry.—In the manufacture of carbon bisulphide little or no danger is run either to health or from fire.
In the rubber trade the poisonous nature of benzine and chloride of sulphur have to be borne in mind, and also the considerable risk of lead poisoning in mixing. Cases of plumbism, especially in earlier years, are referred to.1
Benzine poisoning plays only a secondary part in the rubber industry. No severe cases are recorded, only slight cases following an inhalation of fumes.
Cases of poisoning are recorded in a motor tyre factory in Upsala.2 Nine women were affected, of whom four died. Whether these cases were due to benzene or petroleum benzine is not stated. It is remarkable that two such very different substances as benzene and benzine should be so easily confused.
But that in the rubber industry cases of benzene poisoning do actually occur is proved by the following recent cases: Rubber dissolved in benzol was being laid on a spreading machine in the usual way. Of three men employed one was rendered unconscious and died.3
In a rubber recovery process a worker was rendered unconscious after entering a benzol still, also two others who sought to rescue him. Only one was saved.
Cases of aniline poisoning are reported where aniline is used for extracting rubber.4
Chloride of sulphur, by reason of its properties and the readiness with which it decomposes (see Chloride of Sulphur), causes annoyance to rubber workers, but rarely poisoning.
Much importance attaches to chronic carbon bisulphide poisoning in the rubber industry. Many scientists have experimented as to its poisonous nature (see especially on this Part II, p. 194).
Lehmann’s5 experiments show that a proportion of 0·50-0·7 mg. of CS₂ per litre of air causes hardly any symptoms; 1·0-1·2 mg. slight effects which become more marked on continued exposure; 1·5 mg. produces severe symptoms. About 1·0 mg. per litre of air is the amount which may set up chronic effects. In vulcanising rooms this limit may easily be exceeded unless special preventive measures are adopted.
Laudenheimer6 has made several analyses of the proportion of CS₂ in workrooms. Thus 0·9-1·8 mg. per litre of air were found in a room where pouches were vulcanised; 0·5-2·4 mg. were aspirated one-half metre distant from the dipping vessels; and 0·18-0·27 mg. in the room for making ‘baby comforters.’
In analyses made some years ago proportions of 2·9-5·6 mg. were obtained.
Although literature contains many references to CS₂ poisoning, too much importance ought not to be attached to them now in view of the arrangements in modern well-equipped vulcanising premises. Laudenheimer has collected particulars of 31 cases of brain, and 19 of nervous, diseases among 219 persons coming into contact with CS₂ between 1874 and 1908, all of whom had been medically attended. In the last ten years, however, the psychical symptoms were seven times less than in the preceding period. Between 1896 and 1898 the average proportion of brain disease in the vulcanising department was 1·95 per cent., and of nervous diseases 0·22 per cent., as compared with 0·92 per cent. and 0·03 per cent. in the textile. Moreover, he maintains that practically all workers who come at all into contact with CS₂ must be to some extent affected injuriously by it.
Studies on the injurious nature of CS₂ date from the years 1851-60, when the French writers Pazen, Duchenne, Beaugrand, Piorry, &c., came across cases from the Parkes’ process (cold vulcanisation by means of CS₂ and SCl₂). Delpech7 published in 1860 and 1863 details of twenty-four severe cases in rubber workers, some of which were fatal, and at the same time described the pitiable conditions under which the work was carried on.
In Germany Hermann, Hirt and Lewin, and Eulenberg dealt with the subject, but their work is more theoretical in character; and in Laudenheimer’s work referred to the histories of several cases are given in detail.
Mention should be made of the injury caused to the skin by the fluids used in extraction of fat and in vulcanising—especially by benzine and carbon bisulphide. Perrin considers the effect due partly to the withdrawal of heat and partly to the solvent action on the natural grease, producing an unpleasant feeling of dryness and contraction of the skin.
Illuminating gas is obtained by the dry distillation of coal. The products of distillation are subjected on the gasworks to several purifying processes, such as condensation in coolers, moist and dry purifying, from which valuable bye-products (such as tar, ammonia, cyanogen compounds) are obtained. The purified gas is stored in gas holders containing on an average 49 per cent. hydrogen, 34 per cent. methane, 8 per cent. carbonic oxide, 1 per cent. carbon dioxide, 4 per cent. nitrogen, and about 4 per cent. of the heavy hydrocarbons (ethylene, benzene vapour, acetylene, and their homologues) to which the illuminating properties are almost exclusively due.
The most important stages in its preparation will be shortly described. Distillation is effected in cylindrical, usually horizontal, fireclay retorts placed in a group or setting (fig. 11), which formerly were heated by coke but in modern works always by gas. Charging with coal and removal of the coke takes place about every four hours, often by means of mechanical contrivances.
Iron pipes conduct the products of distillation to the hydraulic main. This is a long covered channel extending the entire length of the stack and receiving the gas and distillate from each retort. In it the greater part of the tar and of the ammoniacal water condense and collect under the water which is kept in the main to act as a seal to the ends of the dip pipes, to prevent the gas from passing back into the retort when the latter is opened. While the liquid flows from the hydraulic main into cisterns, the gas passes into coolers or condensers, tall iron cylinders, in which, as the result of air and water cooling, further portions of the tar and ammoniacal liquor are condensed. To free it still more from particles of tar the gas passes through the tar separator.