The Project Gutenberg EBook of Industrial Poisoning, by Joseph Rambousek This eBook is for the use of anyone anywhere in the United States and most other parts of the world at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.org. If you are not located in the United States, you'll have to check the laws of the country where you are located before using this ebook. Title: Industrial Poisoning From Fumes, Gases and Poisons of Manufacturing Processes Author: Joseph Rambousek Translator: Thomas M. Legge Release Date: November 1, 2019 [EBook #60605] Language: English Character set encoding: UTF-8 *** START OF THIS PROJECT GUTENBERG EBOOK INDUSTRIAL POISONING *** Produced by Suzanne Lybarger, Brian Janes and the Online Distributed Proofreading Team at http://www.pgdp.net INDUSTRIAL POISONING FROM FUMES, GASES AND POISONS OF MANUFACTURING PROCESSES BY THE SAME AUTHOR LEAD POISONING AND LEAD ABSORPTION: THE SYMPTOMS, PATHOLOGY AND PREVENTION, WITH SPECIAL REFERENCE TO THEIR INDUSTRIAL ORIGIN AND AN ACCOUNT OF THE PRINCIPAL PROCESSES INVOLVING RISK. By THOMAS M. LEGGE M.D. (Oxon.), D.P.H. (Cantab.), H.M. Medical Inspector of Factories; Lecturer on Factory Hygiene, University of Manchester; and KENNETH W. GOADBY, D.P.H. (Cantab.), Pathologist and Lecturer on Bacteriology, National Dental Hospital. Illustrated. viii+308 pp. 12s. 6d. net. London: EDWARD ARNOLD. INDUSTRIAL POISONING FROM FUMES, GASES AND POISONS OF MANUFACTURING PROCESSES [i] [ii] [iii] BY DR. J. RAMBOUSEK PROFESSOR OF FACTORY HYGIENE, AND CHIEF STATE HEALTH OFFICER, PRAGUE TRANSLATED AND EDITED BY THOMAS M. LEGGE, M.D., D.P.H. H.M. MEDICAL INSPECTOR OF FACTORIES JOINT AUTHOR OF ‘LEAD POISONING AND LEAD ABSORPTION’ WITH ILLUSTRATIONS LONDON EDWARD ARNOLD 1913 TRANSLATOR’S PREFACE I undertook the translation of Dr. Rambousek’s book because it seemed to me to treat the subject of industrial poisons in as novel, comprehensive, and systematic a manner as was possible within the compass of a single volume. Having learnt much myself from Continental writings on industrial diseases and factory hygiene, I was anxious to let others also see how wide a field they had covered and how thorough were the regulations for dangerous trades abroad, especially in Germany. A praiseworthy feature of Dr. Rambousek’s book was the wealth of references to the work of foreign writers which is made on almost every page. To have left these names and references, however, in the text as he has done would have made the translation tedious reading, and therefore for the sake of those who desire to pursue inquiry further I have adopted the course of collecting the great majority and placing them all together in an appendix at the end of the volume. Dr. Rambousek as a medical man, a chemist, and a government official having control of industrial matters, is equipped with the very special knowledge required to describe the manufacturing processes giving rise to injurious effects, the pathology of the lesions set up, and the preventive measures necessary to combat them. In his references to work done in this country he has relied largely on abstracts which have appeared in medical and technical journals published on the Continent. I have only thought it necessary to amplify his statements when important work carried out here on industrial poisoning,—such as that on nickel carbonyl and on ferro-silicon—had been insufficiently noted. Such additions are introduced in square brackets or in footnotes. In his preface Dr. Rambousek says ‘the book is intended for all who are, or are obliged to be, or ought to be, interested in industrial poisoning.’ No words could better describe the scope of the book. The work of translation would never have been begun but for the assistance given me in Parts II and III by my sister, Miss H. Edith Legge. To her, and to Mr. H. E. Brothers, F.I.C., who has been to the trouble of reading the proofs and correcting many mistakes which my technical knowledge was insufficient to enable me to detect, my best thanks are due. I am indebted to Messrs. Davidson & Co., Belfast, for permission to use figs. 46 and 48; to Messrs. Locke, Lancaster & Co., Millwall, for fig. 27; to Mr. R. Jacobson, for figs. 30, 33, 37, 38, and 43; to Messrs. Siebe, Gorman & Co., for figs. 32, 39, and 40; to Messrs. Blackman & Co. for fig. 47; to Messrs. Matthews & Yates for fig. 54; to H.M. Controller of the Stationery Office for permission to reproduce figs. 52, 53, and 54, and the diagrams on p. 284; and lastly to my publisher, for figs. 41, 42, 43, and 49, which are taken from the book by Dr. K. W. Goadby and myself on ‘Lead Poisoning and Lead Absorption.’ T. M. L. Hampstead, May 1913. CONTENTS PAGE Introduction xiii Part I.—Description of the industries and processes attended with risk of poisoning: incidence of such poisoning Chemical Industry 1 [iv] [v] [vi] [vii] Sulphuric acid industry (sulphur dioxide): use of sulphuric acid 4 Its effects on health 9 Hydrochloric acid, saltcake and soda industry 14 Their effects on health 20 Use of sulphate and sulphide of soda 22 Ultramarine 22 Sulphonal 22 Diethyl sulphate 23 Chlorine, chloride of lime and chlorates 23 Their effect on health 26 Other chlorine compounds and their use as well as bromine, iodine and fluorine 29 Chlorides of phosphorus 30 Chlorides of sulphur 31 Zinc chloride 32 Rock salt 32 Organic chlorine compounds 32 Carbon oxychloride (phosgene) 32 Carbon chlorine compounds (aliphatic) 33 Methyl chloride 33 Methylene chloride 34 Carbon tetrachloride 34 Ethyl chloride 34 Monochloracetic acid 34 Chloral 34 Chloroform 34 Chloride of nitrogen 35 Cyanogen chloride 35 Chlorobenzene 35 Benzo trichloride, benzyl chloride 35 Nitro- and dinitro-chlorobenzene 35 Iodine and iodine compounds 36 Bromine and bromine compounds 36 Methyl iodide and methyl bromide 36 Fluorine compounds 37 Hydrofluoric and silicofluoric acids 38 Manufacture and uses of nitric acid 39 Its effect on health 40 Nitric and nitrous salts and compounds 44 Barium nitrate 44 Ammonium nitrate 44 Lead nitrate 44 Mercurous and mercuric nitrate 44 Silver nitrate 45 Sodium nitrite 45 Amyl nitrite 45 Manufacture of explosives and their effects 45 Fulminate of mercury 46 Nitro-glycerin 46 Dynamite 47 Gun cotton 48 Collodion cotton, smokeless powder 48 Manufacture of phosphorus and lucifer matches and their effects 49 Other uses of phosphorus and compounds of phosphorus 52 Phosphor-bronze 52 Sulphide of phosphorus 52 Phosphoretted hydrogen 52 Superphosphate and artificial manure 53 Basic slag 54 Chromium compounds and their uses 55 Sodium and potassium bichromate 55 Lead chromate and chrome colours 55 [viii] Their effect on health 56 Manganese compounds and their effects 58 Mineral oil industry and the use of petroleum and benzine 59 Chemical cleaning 61 Their effect on health 61 Recovery and use of sulphur 64 Its effect on health 65 Sulphuretted hydrogen and its effect 65 Preparation and use of carbon bisulphide in vulcanising, &c. 68 Its effect on health 69 Preparation of illuminating gas 71 Its effect on health 74 Coke ovens and risk from them 77 Other kinds of power and illuminating gas 80 Producer gas 80 Blast furnace gas 82 Water gas 82 Dowson and Mond gas 82 Suction gas 83 Acetylene (calcium carbide) 85 Their effect on health 87 Ammonia and ammonium compounds 90 Use of ammonia and its effects 92 Cyanogen compounds 93 Use of cyanide, and their effects 95 Coal tar and tar products 96 Their effects on health 101 Artificial organic dye stuffs (coal tar colours) 107 Their effects on health 112 Recovery and use of metals 120 Lead poisoning in general 120 Lead, silver and zinc smelting 122 Spelter works 125 Lead poisoning in lead smelting and spelter works 126 White lead and other use of lead colours 131 Lead poisoning in the manufacture and use of white lead and lead paints 132 Manufacture of electric accumulators 134 The ceramic industry 135 Coarse ware pottery 136 Manufacture of stove tiles 137 Stoneware and porcelain 138 Lead poisoning in letterpress printing 138 Lead poisoning in filecutting, polishing precious stones, musical instrument making, &c. 140 Mercury (poisoning in its recovery and use) 141 Mercurial poisoning in water-gilding, coating mirrors, in felt hat making, &c. 142 Arsenic (poisoning in its recovery and in use of arsenic and arsenic compounds) 143 Recovery of arsenic and white arsenic 143 Poisoning by arseniuretted hydrogen gas 145 Antimony 146 Extraction of iron 146 Ferro-silicon 149 Zinc 151 Copper, brass (brassfounders’ ague) 151 Metal pickling 152 Other Industries 153 Treatment of stone and earths; lime burning, glass 153 Treatment of animal products 154 Preparation of vegetable foodstuffs 154 Poisonous woods 154 Textile industry 156 [ix] Part II.—Pathology and treatment of industrial poisoning Industrial poisons in general 157 Channels of absorption, classification, susceptibility, immunity 158 Fate of poisons in the body—absorption, cumulative action, excretion 162 General remarks on treatment 163 Industrial poisons in particular 169 Group: mineral acids, halogens, inorganic halogen compounds, alkalis 169 Hydrochloric acid 170 Hydrofluoric and silico-fluoric acids 171 Sulphur dioxide and sulphuric acid 171 Nitrous fumes, nitric acid 172 Chlorine, bromine, iodine 173 Chlorides of phosphorus, sulphur and zinc 174 Ammonia 175 Alkalis 176 Group: Metals and metal-compounds 176 Lead and its compounds 177 Zinc and its alloys 182 Mercury and its compounds 183 Manganese and its compounds 184 Chromium and its compounds 185 Nickel salts (nickel carbonyl) 186 Copper 188 Silver and its compounds 188 Group: Arsenic, Phosphorus 189 Arsenic and its oxides 189 Phosphorus 190 Phosphoretted hydrogen 191 Group: Sulphuretted hydrogen, carbon bisulphide, and cyanogen (nerve poisons) 192 Sulphuretted hydrogen 192 Carbon bisulphide 193 Cyanogen compounds 195 Group: Arseniuretted hydrogen and carbonic oxide (blood poisons) 197 Group: Hydrocarbons of the aliphatic and aromatic series and their halogen and hydroxyl substitution products 202 Sub-group: Hydrocarbons of mineral oils and their distillation products (benzine, paraffin, &c.) 202 Sub-group: Hydrocarbons of the aromatic series 204 Benzene and its homologues 204 Naphthalene 208 Sub-group: Halogen substitution products of the aliphatic series (narcotic poisons) 208 Sub-group: Halogen substitution products of the benzene series 209 Sub-group: Hydroxyl substitution products of the fatty series 210 Group: Nitro- and amido-derivatives of the aliphatic and aromatic series 211 Sub-group: Nitro-derivatives of the aliphatic series 212 Sub-group: Nitro- and amido-derivatives of the aromatic series 212 Turpentine, pyridene, alkaloids, nicotine, poisonous woods 215 Part III.—Preventive measures against industrial poisoning General preventive measures 217 International action, notification of poisoning, schedules of poisons 218 Special preventive measures for workers—selection, periodical medical examination, co-operation of workers, &c. 226 Rescue appliances 230 Washing accommodation and baths 237 Removal of dust and fumes by exhaust ventilation 242 Preventive Measures in Particular Industries 256 Sulphuric acid industry 256 Hydrochloric acid and soda industries 257 Chlorine, bleaching powder, chlorine compounds 259 Manufacture of nitric acid and explosives 260 [x] [xi] Artificial manures, basic slag 261 Chromium and its compounds 265 Petroleum, benzine 267 Phosphorus, lucifer matches 268 Bisulphide of carbon 271 Illuminating gas, tar production 275 Gas power plant 276 Acetylene gas installations 278 Ammonia 279 Cyanogen, cyanogen compounds 280 Coal tar, tar products 280 Organic dye-stuffs, coal tar colours 285 Recovery and use of metals 288 Iron 289 Lead 292 Lead smelting 299 Electric accumulators 305 White lead and lead colours 310 Letterpress printing 316 Ceramic industry 319 File cutting 321 Other uses of lead 322 Zinc smelting 323 Brass casting, metal pickling 325 Recovery and use of mercury 326 Arsenic and its compounds 328 Gold and silver 329 Preventive Measures in other trades 329 Manufacture and use of varnishes 330 Production of vegetable foods 332 Wood working 335 Paper manufacture 336 Textile industries 336 Appendix 339 Index 355 INTRODUCTION The attempt to systematise from the scientific standpoint the mass of material that has been collected about poisons is a very heavy task, even for the toxicologist who desires to treat his subject comprehensively. How much greater is the difficulty of writing a systematic book on industrial poisoning keeping practical application in the forefront! Technical considerations which are decisive in the causation and prevention of industrial poisoning are here of especial moment, and must naturally influence classification of the subject-matter when the object is to assist those concerned in factory hygiene. Bearing this in mind, I have divided the subject into three parts. The arrangement of the first, which gives as complete a statement as possible of the occurrence of industrial poisoning, into industries and processes was determined on technical grounds. The second, which amplifies the first, attempts to summarise the pathology or symptoms of the various forms of poisoning. The references to the literature of the particular subjects—as exhaustive as I could make them—will lighten further study. To these two parts, following on knowledge of causation and symptoms, the third, in which preventive measures are outlined, is linked. The apparent drawback in use of the book is that one form of poisoning has often to be referred to in three places. But, I hope, this is more than counterbalanced by the completeness of the scheme which results from the subdivision of the subject. The pathology of industrial poisoning necessitates frequent repetition when describing the branches of industry giving rise to the intoxication, as one and the same form can occur in the most varied processes. The numerous instances of actual cases of poisoning quoted must therefore be regarded as conforming to the same pathological type. Similarly, preventive measures require separate systematic treatment in order to avoid constant repetition which would otherwise obscure the general survey. Quite a number of means of prevention apply equally to several industries in which the same cause is at work. The success attained by thus simplifying the issues is the greater because such common measures are the easier to carry through and to supervise. [xii] [xiii] [xiv] The method therefore has been adopted only after serious reflection and has been directed mainly by practical considerations. Recent cases which have either been reported or come to the knowledge of the author have been given, with particulars as exact as possible. Cases dating back some time have been omitted intentionally so as to exclude everything which did not correspond with the present conditions of industry and trade. Historical facts only receive consideration in so far as they are fundamentally important and necessary for the sake of completeness. The details given in Part I of actual instances will supply material for fresh efforts, renewed investigation, and new points of attack. INDUSTRIAL POISONING PART I DESCRIPTION OF THE INDUSTRIES AND PROCESSES ATTENDED WITH RISK OF POISONING; INCIDENCE OF SUCH POISONING I. THE CHEMICAL INDUSTRY GENERAL CONSIDERATIONS AS TO INCIDENCE OF INDUSTRIAL POISONING The chemical industry offers naturally a wide field for the occurrence of industrial poisoning. Daily contact with the actual poisonous substances to be prepared, used, stored, and despatched in large quantity gives opportunity for either acute or chronic poisoning—in the former case from sudden accidental entrance into the system of fairly large doses, as the result of defective or careless manipulation, and, in the latter, constant gradual absorption (often unsuspected) of the poison in small amount. The industry, however, can take credit for the way in which incidence of industrial poisoning has been kept down in view of the magnitude and variety of the risks which often threaten. This is attributable to the comprehensive hygienic measures enforced in large chemical works keeping abreast of modern advance in technical knowledge. A section of this book deals with the principles underlying these measures. Nevertheless, despite all regulations, risk of poisoning cannot be wholly banished. Again and again accidents and illness occur for which industrial poisoning is responsible. Wholly to prevent this is as impossible as entirely to prevent accidents by mechanical guarding of machinery. Owing to the unknown sources of danger, successful measures to ward it off are often difficult. The rapid advance of this branch of industry, the constant development of new processes and reactions, the frequent discovery of new materials (with properties at first unknown, and for a long time insufficiently understood, but nevertheless indispensable), constantly give rise to new dangers and possibilities of danger, of which an accident or some disease with hitherto unknown symptoms is the first indication. Further, even when the dangerous effects are recognised, there may often be difficulty in devising appropriate precautions, as circumstances may prevent immediate recognition of the action of the poison. We cannot always tell, for instance, with the substances used or produced in the processes, which is responsible for the poisoning, because, not infrequently, the substances in question are not chemically pure, but may be either raw products, bye-products, &c., producing mixtures of different bodies or liberating different chemical compounds as impurities. Hence difficulty often arises in the strict scientific explanation of particular cases of poisoning, and, in a text-book such as this, difficulty also of description. A rather full treatment of the technical processes may make the task easier and help to give a connected picture of the risks of poisoning in the chemical industry. Such a procedure may be especially useful to readers insufficiently acquainted with chemical technology. We are indebted to Leymann1 and Grandhomme2 especially for knowledge of incidence of industrial poisoning in this industry. The statistical data furnished by them are the most important proof that poisoning, at any rate in large factories, is not of very frequent occurrence. Leymann’s statistics relate to a large modern works in which the number employed during the twenty-three years of observation increased from 640 in the year 1891 to 1562 in 1904, giving an average of about 1000 yearly, one-half of whom might properly be defined as ‘chemical workers.’ The factory is concerned in the manufacture of sulphuric, nitric, and hydrochloric acids, alkali, bichromates, aniline, trinitro-phenol, bleaching powder, organic chlorine compounds, and potassium permanganate. These statistics are usefully complemented by those of Grandhomme drawn from the colour works at Höchst a-M. This large aniline works employs from 2600 to 2700 workers; the raw materials are principally benzene and its homologues, naphthalene and anthracene. The manufacture includes the production of coal-tar colours, nitro- and dinitro-benzene, aniline, rosaniline, fuchsine, and other aniline colours, and finally such pharmaceutical preparations as antipyrin, dermatol, sanoform, &c. Of the 2700 employed, 1400 are chemical workers and the remainder labourers. These two series of statistics based on exact observations and covering allied chemical manufacture are taken together. They seek to give the answer to the question—How many and what industrial poisonings are found? The figures of Leymann (on an average of 1000 workers employed per annum) show 285 cases of poisoning reported [1] [2] [3] between the years 1881 and 1904. Of these 275 were caused by aniline, toluidine, nitro- and dinitro-benzene, nitrophenol, nitrochloro and dinitrochloro benzene. Three were fatal and several involved lengthy invalidity (from 30 to 134 days, owing to secondary pneumonia). Included further are one severe case of chrome (bichromate) poisoning (with nephritis as a sequela), five cases of lead poisoning, three of chlorine, and one of sulphuretted hydrogen gas. In the Höchst a-M. factory (employing about 2500 workers) there were, in the ten years 1883-92, only 129 cases of poisoning, of which 109 were due to aniline. Later figures for the years 1893-5 showed 122 cases, of which 43 were due to aniline and 76 to lead (contracted mostly in the nitrating house). Grandhomme mentions further hyperidrosis among persons employed on solutions of calcium chloride, injury to health from inhalation of methyl iodide vapour in the antipyrin department, a fatal case of benzene poisoning (entering an empty vessel in which materials had previously been extracted with benzene), and finally ulceration and perforation of the septum of the nose in several chrome workers. The number of severe cases is not large, but it must be remembered that the factories to which the figures relate are in every respect models of their kind, amply provided with safety appliances and arrangements for the welfare of the workers. The relatively small amount of poisoning is to be attributed without doubt to the precautionary measures taken. Further, in the statistics referred to only those cases are included in which the symptoms were definite, or so severe as to necessitate medical treatment. Absorption of the poison in small amount without producing characteristic symptoms, as is often the case with irritating or corrosive fumes, and such as involve only temporary indisposition, are not included. Leymann himself refers to this when dealing with illness observed in the mineral acid department (especially sulphuric acid), and calls attention to the frequency of affections of the respiratory organs among the persons employed, attributing them rightly to the irritating and corrosive effect of the acid vapour. Elsewhere he refers to the frequency of digestive disturbance among persons coming into contact with sodium sulphide, and thinks that this may be due to the action of sulphuretted hydrogen gas. Nevertheless, the effect of industrial poisons on the health of workers in chemical factories ought on no account to be made light of. The admirable results cited are due to a proper recognition of the danger, with consequent care to guard against it. Not only have Grandhomme and Leymann[A] rendered great services by their work, but the firms in question also, by allowing such full and careful inquiries to be undertaken and published. SULPHURIC ACID (SULPHUR DIOXIDE) Manufacture.—Sulphur dioxide, generally obtained by roasting pyrites in furnaces of various constructions, or, more rarely, by burning brimstone or sulphur from the spent oxide of gas-works, serves as the raw material for the manufacture of sulphuric acid. Before roasting the pyrites is crushed, the ‘lump ore’ then separated from the ‘smalls,’ the former roasted in ‘lump-burners’ or kilns (generally several roasting furnace hearths united into one system), and the latter preferably in Malétra and Malétra-Schaffner shelf-burners (fig. 1) composed of several superimposed firebrick shelves. The pyrites is charged on to the uppermost shelf and gradually worked downwards. Pyrites residues are not suitable for direct recovery of iron, but copper can be recovered from residues sufficiently rich in metal by the wet process; the residues thus freed of copper and sulphur are then smelted for recovery of iron. FIG. 1.—Pyrites Burner for Smalls (after Lueger) Utilisation for sulphuric acid manufacture of the sulphur dioxide given off in the calcining of zinc blende (see Spelter works), impracticable in reverberatory furnaces, has been made possible at the Rhenania factory by introduction of muffle furnaces (several superimposed), because by this means the gases led off are sufficiently concentrated, as they are not diluted with the gases and smoke from the heating fires. This method, like any other which utilises the gases from roasting furnaces, has great hygienic, in addition to economical, advantages, because escape of sulphur dioxide gas is avoided. Furnace gases, too poor in sulphur dioxide to serve for direct production of sulphuric acid, can with advantage be made to produce liquid anhydrous sulphur dioxide. Thus, the sulphur dioxide gas from the furnaces is first absorbed by water, driven off again by boiling, cooled, dried, and liquefied by pressure. The gaseous sulphur dioxide obtained by any of the methods described is converted into sulphuric acid either by (a) the chamber process or (b) the contact process. In the lead chamber process the furnace gases pass through flues in which the flue dust and a portion of the arsenious [4] [5] [6] acid are deposited into the Glover tower at a temperature of about 300° C., and from there into the lead chambers where oxidation of the sulphur dioxide into sulphuric acid takes place, in the presence of sufficient water, by transference of the oxygen of the air through the intervention of the oxides of nitrogen. The gases containing oxides of nitrogen, &c., which are drawn out of the lead chambers, have the nitrous fumes absorbed in the Gay-Lussac tower (of which there are one or two in series), by passage through sulphuric acid which is made to trickle down the tower. The sulphuric acid so obtained, rich in oxides of nitrogen, and the chamber acid are led to the Glover tower for the purpose of denitration and concentration, so that all the sulphuric acid leaves the Glover as Glover acid of about 136-144° Tw. Losses in nitrous fumes are best made up by addition of nitric acid at the Glover or introduction into the first chamber. The deficiency is also frequently made good from nitre-pots. The lead chambers (fig. 2) are usually constructed entirely—sides, roof, and floor—of lead sheets, which are joined together by means of a hydrogen blowpipe. The sheets forming the roof and walls are supported, independent of the bottom, on a framework of wood. The capacity varies from 35,000 to 80,000 cubic feet. The floor forms a flat collecting surface for the chamber acid which lutes the chamber from the outer air. The necessary water is introduced into the chamber as steam or fine water spray. The Glover and Gay-Lussac towers are lead towers. The Glover is lined with acid-proof bricks and filled with acid-proof packing to increase the amount of contact. The Gay-Lussac is filled with coke over which the concentrated sulphuric acid referred to above flows, forming, after absorption of the nitrous fumes, nitro-sulphuric acid. FIG. 2A.—Lead Chamber System—Section through X X (after Ost) FIG. 2B.—Lead Chamber System—Plan A Pyrites Burner B Glover Tower C Draft Regulator D, D´ Lead Chambers E Air Shaft F, F,´ F,´´ F´´´ Acid Reservoirs G Acid Egg H Cooler J Gay-Lussac Tower [7] As already stated, two Gay-Lussac towers are usually connected together, or where there are several lead-chamber systems there is, apart from the Gay-Lussac attached to each, a central Gay-Lussac in addition, common to the whole series. The introduction of several Gay-Lussac towers has the advantage of preventing loss of the nitrous fumes as much as possible—mainly on economical grounds, as nitric acid is expensive. But this arrangement is at the same time advantageous on hygienic grounds, as escape of poisonous gases containing nitrous fumes, &c., is effectually avoided. The acids are driven to the top of the towers by compressed air. The whole system—chambers and towers—is connected by means of wide lead conduits. Frequently, for the purpose of quickening the chamber process (by increasing the number of condensing surfaces) Lunge-Rohrmann plate towers are inserted in the system—tall towers lined with lead in which square perforated plates are hung horizontally, and down which diluted sulphuric acid trickles. To increase the draught in the whole system a chimney is usual at the end, and, in addition, a fan of hard lead or earthenware may be introduced in front of the first chamber or between the two Gay-Lussac towers. Maintenance of a constant uniform draught is not only necessary for technical reasons, but has hygienic interest, since escape of injurious gases is avoided (see also Part III). The chamber acid (of 110°-120° Tw. = 63-70 %) and the stronger Glover acid (of 136°-144° Tw. = 75-82 %) contain impurities. In order to obtain for certain purposes pure strong acid the chamber acid is purified and concentrated. The impurities are notably arsenious and nitrous acids (Glover acid is N free), lead, copper, and iron. Concentration (apart from that to Glover acid in the Glover tower) is effected by evaporation in lead pans to 140° Tw. and finally in glass balloons or platinum stills to 168° Tw. (= 97 %). The lead pans are generally heated by utilising the waste heat from the furnaces or by steam coils in the acid itself, or even by direct firing. Production of sulphuric acid by the contact method depends on the fact that a mixture of sulphur dioxide and excess of oxygen (air) combines to form sulphur trioxide at a moderate heat in presence of a contact substance such as platinised asbestos or oxide of iron. The sulphur dioxide must be carefully cleaned and dried, and with the excess of air is passed through the contact substance. If asbestos carrying a small percentage of finely divided platinum is the contact substance, it is generally used in the form of pipes; oxide of iron (the residue of pyrites), if used, is charged into a furnace. Cooling by a coil of pipes and condensation in washing towers supplied with concentrated sulphuric acid always forms a part of the process. A fan draws the gases from the roasting furnaces and drives them through the system. The end product is a fuming sulphuric acid containing 20-30 per cent. SO₃. From this by distillation a concentrated acid and a pure anhydride are obtained. From a health point of view it is of importance to know that all sulphuric acid derived from this anhydride is pure and free from arsenic. The most important uses of sulphuric acid are the following: as chamber acid (110°-120° Tw.) in the superphosphate, ammonium sulphate, and alum industries; as Glover acid (140°-150° Tw.) in the Leblanc process, i.e. saltcake and manufacture of hydrochloric acid, and to etch metals; as sulphuric acid of 168° Tw. in colour and explosives manufacture (nitric acid, nitro-benzene, nitro-glycerine, gun-cotton, &c.); as concentrated sulphuric acid and anhydride for the production of organic sulphonic acids (for the alizarin and naphthol industry) and in the refining of petroleum and other oils. Completely de-arsenicated sulphuric acid is used in making starch, sugar, pharmaceutical preparations, and in electrical accumulator manufacture. Effects on Health.—The health of sulphuric acid workers cannot in general be described as unfavourable. In comparison with chemical workers they have, it is said, relatively the lowest morbidity. Although in this industrial occupation no special factors are at work which injure in general the health of the workers, there is a characteristic effect, without doubt due to the occupation—namely, disease of the respiratory organs. Leymann’s figures are sufficiently large to show that the number of cases of diseases of the respiratory organs is decidedly greater in the sulphuric acid industry than among other chemical workers. He attributes this to the irritating and corrosive effect of sulphur dioxide and sulphuric acid vapour on the mucous membrane of the respiratory tract, as inhalation of these gases can never be quite avoided, because the draught in the furnace and chamber system varies, and the working is not always uniform. Strongly irritating vapours escape again in making a high percentage acid in platinum vessels, which in consequence are difficult to keep air-tight. Of greater importance than these injurious effects from frequent inhalation of small quantities of acid vapours, or employment in workrooms in which the air is slightly charged with acid, is the accidental sudden inhalation of large quantities of acid gases, which may arise in the manufacture, especially by careless attendance. Formerly this was common in charging the roasting furnaces when the draught in the furnace, on addition of the pyrites, was not strengthened at the same time. This can be easily avoided by artificial regulation of the draught. Accidents through inhalation of acid gases occur further when entering the lead chambers or acid tanks, and in emptying the towers. Heinzerling relates several cases taken from factory inspectors’ reports. Thus, in a sulphuric acid factory the deposit (lead oxysulphate) which had collected on the floor of a chamber was being removed: to effect this the lead chambers were opened at the side. Two of the workers, who had probably been exposed too long to the acid vapours evolved in stirring up the deposit, died a short time after they had finished the work. A similar fatality occurred in cleaning out a nitro-sulphuric acid tank, the required neutralisation of the acid by lime before entering having been omitted. Of the two workers who entered, one died the next day; the other remained unaffected. The deceased had, as the post mortem showed, already suffered previously from pleurisy. A fatality from breathing nitrous fumes is described fully in the report of the Union of Chemical Industry for the year 1905. The worker was engaged with two others in fixing a fan to a lead chamber; the workers omitted to wait for the arrival of the foreman who was to have supervised the operation. Although the men used moist sponges as respirators, one of them inhaled nitrous fumes escaping from the chamber in such quantity that he died the following day. Similar accidents have occurred in cleaning out the Gay-Lussac towers. Such poisonings have repeatedly occurred in Germany. Fatal poisoning is recorded in the report of the Union of Chemical Industry, in the emptying and cleaning of a [8] [9] [10] [11] Gay-Lussac tower despite careful precautions. The tower, filled with coke, had been previously well washed with water, and during the operation of emptying, air had been constantly blown through by means of a Körting’s injector. The affected worker had been in the tower about an hour; two hours later symptoms of poisoning set in which proved fatal in an hour despite immediate medical attention. As such accidents kept on recurring, the Union of Chemical Industry drew up special precautions to be adopted in the emptying of these towers, which are printed in Part III. Naturally, in all these cases it is difficult to say exactly which of the acid gases arising in the production of sulphuric acid was responsible for the poisoning. In the fatal cases cited, probably nitrous fumes played the more important part. Poisoning has occurred in the transport of sulphuric acid. In some of the cases, at all events, gaseous impurities, especially arseniuretted hydrogen, were present. Thus, in the reports of the German Union of Chemical Industry for the year 1901, a worker succumbed through inhalation of poisonous gases in cleaning out a tank waggon for the transport of sulphuric acid. The tank was cleaned of the adhering mud, as had been the custom for years, by a man who climbed into it. No injurious effects had been noted previously at the work, and no further precautions were taken than that one worker relieved another at short intervals, and the work was carried on under supervision. On the occasion in question, however, there was an unusually large quantity of deposit, although the quality of the sulphuric acid was the same, and work had to be continued longer. The worker who remained longest in the tank became ill on his way home and died in hospital the following day; the other workers were only slightly affected. The sulphuric acid used by the firm in question immediately before the accident came from a newly built factory in which anhydrous sulphuric acid had been prepared by a special process. The acid was Glover acid, and it is possible that selenium and arsenic compounds were present in the residues. Arseniuretted hydrogen might have been generated in digging up the mud. Two similar fatalities are described in the report of the same Union for the year 1905. They happened similarly in cleaning out a sulphuric acid tank waggon, and in them the arsenic in the acid was the cause. Preliminary swilling out with water diluted the remainder of the sulphuric acid, but, nevertheless, it acted on the iron of the container. Generation of hydrogen gas is the condition for the reduction of the arsenious acid present in sulphuric acid with formation of arseniuretted hydrogen. In portions of the viscera arsenic was found. Lately in the annual reports of the Union of Chemical Industry for 1908 several cases of poisoning are described which were caused by sulphuric acid. A worker took a sample out of a vessel of sulphuric acid containing sulphuretted hydrogen gas. Instead of using the prescribed cock, he opened the man-hole and put his head inside, inhaling concentrated sulphuretted hydrogen gas. He became immediately unconscious and died. Through ignorance no use was made of the oxygen apparatus. Another fatality occurred through a foreman directing some workers, contrary to the regulations against accidents from nitrous gases, to clean a vessel containing nitric and sulphuric acids. They wore no air helmets: one died shortly after from inhalation of nitrous fumes. Under certain circumstances even the breaking of carboys filled with sulphuric acid may give rise to severe poisoning through inhalation of acid gases. Thus a fatality1 occurred to the occupier of a workroom next some premises in which sulphuric acid carboys had been accidentally broken. Severe symptoms developed the same night, and he succumbed the next morning in spite of treatment with oxygen. A worker in the factory became seriously ill but recovered. A similar case is described2 in a factory where concentrated sulphuric acid had been spilt. The workers covered the spot with shavings, which resulted in strong development of sulphur dioxide, leading to unconsciousness in one worker. The frequent observation of the injurious effect of acid gases on the teeth of workers requires mention; inflammation of the eyes of workers also is attributed to the effects of sulphuric acid. Leymann’s statistics show corrosions and burns among sulphuric acid workers to be more than five times that among other classes. Such burns happen most frequently from carelessness. Thus, in the reports of the Union of Chemical Industry for 1901, three severe accidents are mentioned which occurred from use of compressed air. In two cases the acid had been introduced before the compressed air had been turned off; in the third the worker let the compressed air into the vessel and forgot to turn off the inlet valve. Although the valves were provided with lead guards, some of the acid squirted into the worker’s face. In one case complete blindness followed, in a second blindness in one eye, and in the third blindness in one eye and impaired vision of the other. Besides these dangers from the raw material, bye-products, and products of the manufacture, lead poisoning has been reported in the erection and repair of lead chambers. The lead burners generally use a hydrogen flame; the necessary hydrogen is usually made from zinc and sulphuric acid and is led to the iron by a tube. If the zinc and sulphuric acid contain arsenic, the very dangerous arseniuretted hydrogen is formed, which escapes through leakages in the piping, or is burnt in the flame to arsenious acid. Further, the lead burners and plumbers are exposed to the danger of chronic lead poisoning from insufficient observance of the personal precautionary measures necessary to guard against it (see Part III). Those who are constantly engaged in burning the lead sheets and pipes of the chambers suffer not infrequently from severe symptoms. Unfortunately, the work requires skill and experience, and hence alternation of employment is hardly possible. Finally, mention should be made of poisoning by arseniuretted hydrogen gas from vessels filled with sulphuric acid containing arsenic as an impurity, and by sulphuretted hydrogen gas in purifying the acid itself. In the manufacture of liquid sulphur dioxide, injury to health can arise from inhalation of the acid escaping from the apparatus. The most frequent cause for such escape of sulphur dioxide is erosion of the walls of the compressor pumps and of the transport vessels, in consequence of the gas being insufficiently dried, as, when moist, it attacks iron. Sulphur dioxide will come up for further consideration when describing the industrial processes giving rise to it, or in which it is used. HYDROCHLORIC ACID, SALTCAKE, AND SODA [12] [13] [14] Manufacture.—The production of hydrochloric acid (HCl), sodium sulphate (Na₂SO₄), and sodium sulphide (Na₂S) forms part of the manufacture of soda (Na₂CO₃) by the Leblanc process. The products first named increase in importance, while the Leblanc soda process is being replaced more and more by the manufacture of soda by the Solvay ammonia process, so much so that on the Continent the latter method predominates and only in England does the Leblanc process hold its ground. Health interests have exercised an important bearing on the development of the industries in question. At first, in the Leblanc process the hydrochloric acid gas was allowed to escape into the atmosphere, being regarded as a useless bye- product. Its destructive action on plant life and the inconvenience caused to the neighbourhood, in spite of erection of high chimneys, demanded intervention. In England the evils led to the enactment of the Alkali Acts—the oldest classical legislative measures bearing on factory hygiene—by which the Leblanc factories were required to condense the vapour by means of its absorption in water, and this solution of the acid is now a highly valued product. And, again, production of nuisance— inconvenience to the neighbourhood through the soda waste—was the main cause of ousting one of the oldest and most generally used methods of chemical industrial production. Although every effort was made to overcome the difficulties, the old classical Leblanc process is gradually but surely yielding place to the modern Solvay process, which has no drawback on grounds of health. We outline next the main features of the Leblanc soda process, which includes, as has been mentioned, also the manufacture of hydrochloric acid, sodium sulphate and sulphide. The first part of the process consists in the production of the sulphate from salt and sulphuric acid, during which hydrochloric acid is formed; this is carried out in two stages represented in the following formulæ: 1. NaCl + H₂SO₄ = NaHSO₄ + HCl. 2. NaCl + NaHSO₄ = Na₂SO₄ + HCl. The first stage in which bisulphate is produced is carried out at a moderate heat, the second requires a red heat. The reactions, therefore, are made in a furnace combining a pan and muffle furnace. This saltcake muffle furnace is so arranged that the pan can be shut off from the muffle by a sliding-door (D). The pan (A) and muffle (E) have separate flues for carrying off the hydrochloric acid developed (B, F). First, common salt is treated with sulphuric (Glover) acid in the cast-iron pan. When generation of hydrochloric acid vapour has ceased, the sliding-door is raised and the partly decomposed mixture is pushed through into the muffle, constructed of fire-resisting bricks and tiles, and surrounded by the fire gases. While the muffle is being raised to red heat, the sulphate must be repeatedly stirred with a rake in order, finally, while still hot and giving off acid vapour, to be drawn out at the working doors into iron boxes provided with doors, where the material cools. The acid vapour given off when cooling is drawn through the top of the box into the furnace. FIG. 3.—Saltcake Muffle Furnace—Section (after Ost) A Pan; B, F Pipes for hydrochloric acid vapour; D Shutter; E Muffle, O Coke fire. Mechanical stirrers, despite their advantage from a health point of view, have not answered because of their short life. The valuable bye-product of the sulphate process, hydrochloric acid, is led away separately from the pan and the muffle, as is seen, into one absorption system. The reason of the separation is that the gas from the pan is always the more concentrated. The arrangement of the absorbing apparatus is illustrated in fig. 4. FIG. 4A.—Preparation of Hydrochloric Acid—Plan (after Lueger) A, A´ Earthenware pipes B, B´ Sandstone cooling towers C, C Series of Woulff’s bottles D, E Condenser wash towers [15] [16] FIG. 4B.—Elevation The gases are led each through earthenware pipes or channels of stone pickled with tar (A´), first into small towers of Yorkshire flags (B), where they are cooled and freed from flue dust and impurities (sulphuric acid) by washing. They are next led through a series (over fifty) of Woulff bottles (bombonnes) one metre high, made of acid-resisting stoneware. The series is laid with a slight inclination towards the furnace, and water trickles through so that the gases coming from the wash towers are brought into contact with water in the one case already almost saturated, whilst the gas which is poorest in hydrochloric acid meets with fresh water. From the bombonne situated next to the wash tower the prepared acid is passed as a rule through another series. The last traces of hydrochloric acid are then removed by leading the gases from the Woulff bottles up two water towers of stoneware (D and E), which are filled partly with earthenware trays and partly with coke; above are tanks from which the water trickles down over the coke. The residual gases from both sets of absorbing apparatus now unite in a large Woulff bottle before finally being led away through a duct to the chimney stack. Less frequently absorption of hydrochloric acid is effected without use of Woulff bottles, principally in wash towers such as the Lunge-Rohrmann plate tower. In the purification of hydrochloric acid, de-arsenicating by sulphuretted hydrogen or by barium sulphide, &c., and separation of sulphuric acid by addition of barium chloride, have to be considered. Another method for production of sulphate and hydrochloric acid, namely, the Hargreaves process, is referred to later. We return now to the further working up of the sodium sulphate into sulphide and soda. The conversion of the sulphate into soda by the Leblanc method is effected by heating with coal and calcium carbonate, whereby, through the action of the coal, sodium sulphide forms first, which next with the calcium carbonate becomes converted into sodium carbonate and calcium sulphide. The reactions are: Na₂SO₄ + 2C = Na₂S + 2CO₂ Na₂S + CaCO₃ = Na₂CO₃ + CaS CaCO₃ + C = CaO + 2CO. The reactions are carried out in small works in open reverberatory furnaces having two platforms on the hearth, and with continuous raking from one to the other which, as the equations show, cause escape of carbonic acid gas and carbonic oxide. Such handworked furnaces, apart from their drawbacks on health grounds, have only a small capacity, and in large works their place is taken by revolving furnaces—closed, movable cylindrical furnaces—in which handwork is replaced by the [17] [18] mechanical revolution of the furnace and from which a considerably larger output and a product throughout good in quality are obtained. The raw soda thus obtained in the black ash furnace is subjected to lixiviation by water in iron tanks in which the impurities or tank waste (see below) are deposited. The crude soda liquor so obtained is then further treated and converted into calcined soda, crystal soda, or caustic soda. In the production of calcined soda the crude soda liquor is first purified (‘oxidised’ and ‘carbonised’) by blowing through air and carbonic acid gas, pressed through a filter press, and crystallised by evaporation in pans and calcined, i.e. deprived of water by heat. FIG. 5.—Revolving Black Ash Furnace—Elevation (after Lueger) A Firing hearth; B Furnace; C Dust box. Crystal soda is obtained from well-purified tank liquor by crystallising in cast-iron vessels. Caustic soda is obtained by introducing lime suspended in iron cages into the soda liquor in iron caustic pots, heating with steam, and agitating by blowing in air. The resulting clear solution is drawn off and evaporated in cast-iron pans. As already mentioned, the tank waste in the Leblanc process, which remains behind—in amount about equal to the soda produced after lixiviation of the raw soda with water—constitutes a great nuisance. It forms mountains round the factories, and as it consists principally of calcium sulphide and calcium carbonate, it easily weathers under the influence of air and rain, forming soluble sulphur compounds and developing sulphuretted hydrogen gas—an intolerable source of annoyance to the district. At the same time all the sulphur introduced into the industry as sulphuric acid is lost in the tank waste. This loss of val...