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This page contains a formula or preparation using substances now known to be dangerously toxic, such as arsenic, mercury, lead, or cyanide compounds. Exposure to these substances can cause severe poisoning, permanent injury, or death.
In addition, this page describes trade processes that use dangerously toxic materials such as cyanide solutions, mercury amalgams, or strong acids. These processes require training, equipment, and precautions far beyond what the text describes.
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Pure Sulphurous Acid
In order to prepare sulphurous acid from sulthem and the other bases, forming salts called NITRATES. Two strengths of this acid occur in the arts, known as double and single aqua-fortis. Double aqua-fortis has usually a specific gravity of 1.36, and single, or ordinary aqua-fortis 1.22. Both are frequently sold at lower strengths. This can easily be ascertained by acidimetry. (See No. 78.) 3873. Το Obtain Nitric Acid. The usual method adopted for obtaining this acid is to add to nitrate of potassa in coarse powphuric acid and charcoal, it is better to em- der, contained in a glass retort, an equal ploy an acid of .74 per cent., or 1.825 specific weight of strong sulphuric acid, poured in gravity. If we take a stronger acid, a part of through a funnel, so as not to wet the neck of it is entirely deoxidized to sulphur, and if the retort. The materials should not exceed weaker acid be employed, sulphuretted hy-two-thirds of the capacity of the retort. A drogen is evolved. To obtain absolutely pure moderate heat is at first applied, increasing as sulphurous acid, it is well to put sulphite of the materials begin to thicken. Red vapors lead and coarse charcoal in the wash bottle. will at first arise and pass over into the re- With these precautions, it is possible to obtain pure sulphurous acid from sulphuric acid and charcoal.