ANTIDOTE TO PRUSSIC ACID. 
227 
extent for the moisture and impurities of the salt of tartar, 
instead of using 15.7 grains, which is the correct quantity 
when in a pure state, twenty grains should be used. We 
would not recommend more than this, as an excess of alkali 
would so far prevent or redissolve the precipitate, causing 
the production of prussiate of potash ; which, although it 
has been found to have no poisonous action on the human 
body, yet it seems better that the poison should be separated 
in an insoluble form. 
To render our meaning more precise and clear, and less 
likely to be misunderstood, we will briefly state the course 
which we think ought to be adopted. On the one hand, 
dissolve ten grains of sulphate of protoxide of iron, or green 
vitriol, in an ounce of water, using a mortar to hasten solu- 
tion, and adding one drachm of the tincture of muriate of 
iron. Put this liquid into a phial, and in another phial dis- 
solve twenty grains of carbonate of potash, or, according to 
its common name, salt of tartar, in another ounce or two of 
water, and to prevent delay— the serious consequences of 
which cannot be two strongly impressed on the mind, as 
every moment bears a swift message of life or death to a 
human being — dispense with labelling, and let the person 
who prepares the antidote, if possible, go at once and give 
it himself. 
The action of the antidote forms of itself a very pretty 
and interesting experiment, which may be shown in the 
following way: — Dissolve in one glass, containing a little 
water, eight grains of carbonate of potash, adding twenty 
or thirty drops of medicinal prussic acid, and in another 
glass, five grains of green vitriol in half an ounce of water, 
adding half a drachm of tincture of muriate of iron. Mix 
the two liquids together. As there is too small a quantity 
of prussic acid present to convert the whole of the iron into 
Prussian blue, the colour of this is masked by oxide of iron 
thrown down at the same time; but on adding a sufficient 
