The deposit on the floor of waggons or tanks shall be removed either by flushing with water without entering the tank itself, or if the tank be entered the deposit is to be scooped out without addition of water or dilute soda solution.
Flushing out shall only be done after the workmen have got out.
Workmen are to be warned every time cleaning is undertaken that poisonous gases are developed when the deposit on the floor is diluted.
Acid eggs, further, are to be provided with a waste pipe and manhole to enable cleaning to be done from outside.
The poisoning likely to arise is partly due to arsenic impurity (development of arseniuretted hydrogen gas) in the sulphuric acid used. Unfortunately arsenic free acid is very difficult to obtain.
Hydrochloric Acid—Saltcake and Soda Industries
(See also pp. [15-23] and [170])
Preventive measures here depend upon observance of the general principles already discussed.
The saltcake pan and reverberatory furnace require to be accurately and solidly constructed and the process carefully regulated. Regulations indeed were drawn up at an early date in England as to their working to prevent escape of gases when adding the acid, raking over in the reverberatory furnace, and withdrawal of the still fuming saltcake.
The following are the most important of these recommendations: