Читать книгу Industrial Poisoning from Fumes, Gases and Poisons of Manufacturing Processes - Josef Rambousek - Страница 13

Chlorine is used for the production of a number of organic chlorine compounds, and in the manufacture of bromine and iodine, processes which give rise to the possibility of injury to health and poisoning by chlorine; further, several of the substances so prepared are themselves corrosive or irritating or otherwise poisonous. Nevertheless, severe poisoning and injurious effects can be almost entirely avoided by adoption of suitable precautions. In the factory to which Leymann’s figures refer, where daily several thousand kilos of chlorine and organic chlorine compounds are prepared, a relatively very favourable state of health of the persons employed was noted. At all events the preparation of chlorine by the electrolytic process takes place in closed vessels admirably adapted to avoid any escape of chlorine gas except as the result of breakage of the apparatus or pipes. When this happens, however, the pipes conducting the gas can be immediately disconnected and the chlorine led into other apparatus or into the bleaching powder factory.

As such complete precautionary arrangements are not everywhere to be found, we describe briefly the most important of the industries in question and the poisoning recognised in them.

Chlorides of phosphorus.—By the action of dry chlorine on an excess of heated amorphous phosphorus, trichloride is formed (PCl₃), a liquid having a sharp smell and causing lachrymation, which fumes in the air, and in presence of water decomposes into phosphorous acid and hydrochloric acid. On heating with dry oxidising substances it forms phosphorus oxychloride (see below), which is used for the production of acid chlorides. By continuous treatment with chlorine it becomes converted into phosphorus pentachloride (PCl₅), which also is conveniently prepared by passing chlorine through a solution of phosphorus in carbon bisulphide, the solution being kept cold; it is crystalline, smells strongly, and attacks the eyes and lungs. With excess of water it decomposes into phosphoric acid and hydrochloric acid: with slight addition of water it forms phosphorus oxychloride (POCl₃). On the large scale this is prepared by reduction of phosphate of lime in the presence of chlorine with carbon or carbonic oxide. Phosphorus oxychloride, a colourless liquid, fumes in the air and is decomposed by water into phosphoric acid and hydrochloric acid.

In the preparation of chlorides of phosphorus, apart from the danger of chlorine gas and hydrochloric acid, the poisonous effect of phosphorus and its compounds (see Phosphorus) and even of carbon disulphide (as the solvent of phosphorus) and of carbonic oxide (in the preparation of phosphorus oxychloride) have to be taken into account.

Further, the halogen compounds of phosphorus exert irritant action on the eyes and lungs similar to chloride of sulphur as a result of their splitting up on the moist mucous membranes into hydrochloric acid and an oxyacid of phosphorus.4

Unless, therefore, special measures are taken, the persons employed in the manufacture of phosphorus chlorides suffer markedly from the injurious emanations given off.5

Leymann6 mentions one case of poisoning by phosphorus chloride as having occurred in the factory described by him. By a defect in the outlet arrangement phosphorus oxychloride flowed into a workroom. Symptoms of poisoning (sensation of suffocation, difficulty of breathing, lachrymation, &c.) at once attacked the occupants; before much gas had escaped, the workers rushed out. Nevertheless, they suffered from severe illness of the respiratory organs (bronchial catarrh and inflammation of the lungs, with frothy, blood-stained expectoration, &c.).7

Chlorides of sulphur.—Monochloride of sulphur (S₂Cl₂) is made by passing dried, washed chlorine gas into molten heated sulphur. The oily, brown, fuming liquid thus made is distilled over into a cooled condenser and by redistillation purified from the sulphur carried over with it. Sulphur monochloride can take up much sulphur, and when saturated is used in the vulcanisation of indiarubber, and, further, is used to convert linseed and beetroot oil into a rubber substitute. Monochloride of sulphur is decomposed by water into sulphur dioxide, hydrochloric acid, and sulphur. By further action of chlorine on the monochloride, sulphur dichloride (SCl₂) and the tetrachloride (SCl₄) are formed.

In its preparation and use (see also Indiarubber Manufacture) the injurious action of chlorine, of hydrochloric acid, and of sulphur dioxide comes into play.

The monochloride has very irritating effects. Leymann cites an industrial case of poisoning by it. In the German factory inspectors’ reports for 1897 a fatal case is recorded. The shirt of a worker became saturated with the material owing to the bursting of a bottle. First aid was rendered by pouring water over him, thereby increasing the symptoms, which proved fatal the next day. Thus the decomposition brought about by water already referred to aggravated the symptoms.

Zinc chloride (ZnCl₂) is formed by heating zinc in presence of chlorine. It is obtained pure by dissolving pure zinc in hydrochloric acid and treating this solution with chlorine. Zinc chloride is obtained on the large scale by dissolving furnace calamine (zinc oxide) in hydrochloric acid. Zinc chloride is corrosive. It is used for impregnating wood and in weighting goods. Besides possible injury to health from chlorine and hydrogen chloride, risk of arseniuretted hydrogen poisoning is present in the manufacture if the raw materials contain arsenic. Eulenburg considers that in soldering oppressive zinc chloride fumes may come off if the metal to be soldered is first wiped with hydrochloric acid and then treated with the soldering iron.

Rock salt.—Mention may be made that even to salt in combination with other chlorides (calcium chloride, magnesium chloride, &c.) injurious effects are ascribed. Ulcers and perforation of the septum of the nose in salt-grinders and packers who were working in a room charged with salt dust are described.8 These effects are similar to those produced by the bichromates.