140 
ON AN ANTIDOTE AT ONCE EOll 
The dogs that got the poison without the antidote died. The dogs that got 
the antidote after the poison, lived and did well. In all cases, a much larger 
dose than a merely dangerous one was given, and no prussic acid could be 
leeovered, by distillation, from the stomachs of the dead dogs. Cases of 
poisoning by prussic acid are frequent enough; but death takes place with 
such frightful rapidity, that this antidote is almost sure to be unattainable 
within the brief period in which it could be at all of any service; and that 
more especially, because the antidote requires to be expressly prepared; its 
being in readiness for a contingency which may never occur, not being likely, 
except v ith ouiselves, and, perhaps, one or two others. "While thinking over 
this matter, it has occurred to us, that in liquor ferri percliloridi of the British 
Pliai macopceia, a remedy may be found for the obstacles that have hitherto 
existed to the use of the prussic acid antidote. "We proceed to show that the 
time taken to supply the antidote need not be greater than would be necessary 
1 and measure two or three articles always at hand. The principle 
of the action of the antidote is exceedingly simple and easily understood ; at 
least, if certain theoretical views be put aside, and the reaction with prussic 
acid be merely considered as a simple case of double decomposition, which 
results in the formation, in the stomach, of the harmless compound kno’ftfti 
as Prussian blue. The formula of Prussian blue is 2 (Fe 2 , Cy 3 ) + 3 (Fe, Cy); 
showing that 7 equivalents of iron and 9 equivalents of cyanogen are con¬ 
tained in one equivalent of the compound. To produce this compound with 
the prussic acid there are required 7 equivalents of iron in the form of a solu¬ 
ble compound, of which four equivalents must be in the state of persalt, and 
o equivalents in the state of protosalt. The ready means of obtaining this 
solution are supplied in the liq. ferri perchloridi, and protosulphate of iron or 
gi.een vitriol. It is easy to find the quantity of the perchloride solution, con¬ 
taining m grains, 4 equivalents of iron. 2 ounces, or 875 grains, are con¬ 
tained in 10 fluid ounces of the solution. Iveeping now in mind that 4 equi- 
a alents of iron must be in the state of peroxide, or perchloride, which is equi- 
■valent; the quantity of perchloride solution required in the production of an 
equiT alent ot 1 russian blue, may be found without any difficulty, thus :— 
Grs. Iron. FI. oz. Sol. 4 eq. Iron FI. oz Sol. 
. 8/5 : 10 : : 112 : P28, or 614 minims. 
. J-he o equivalents of iron in the form of protosalt, required for the forma¬ 
tion of Prussian blue, are supplied as sulphate of protoxide of iron, the equi¬ 
valent of which is 139 ; multiplying that number by 3, gives 417 grains. 
It must be quite clear, therefore, that 614 minims of solution of perchloride 
of iion, and 417 grains of green vitriol, supply the iron in the form and quan- 
tify necessary for the production of Prussian blue ; and as these ingredients 
contain, respectively, 6 equivalents of chlorine and 3 equivalents of sulphuric 
acid (which in Prussian blue are replaced by 9 equivalents of prussic acid), it 
is evident, as the equivalent of prussic acid is 27, that 9 times that sum is 
gi^ins of prussic acid can, consequently, be destroyed by the above 
quantities; therefore, the hundredth of that quantity, or 2’4 grains (a good 
deal more than 100 minims of medicinal prussic acid), can be destroyed as a 
poison by 6T4 minims of solution of perchloride of iron, and 4T7 grains of 
green vitriol; but we need hardly say that prussic acid can take the place of 
neither hydrochloric nor sulphuric acid, unless, at the same time, an equiva¬ 
lent quantity of a strong base is supplied, to take the strong acid from the 
iion, the ahinity of which is comparatively weak. Under such circumstances, 
tiie iron at once seizes on the prussic acid, and the desired result is obtained,— 
rni 1J ? atl0I S a ^ iarm ^ ess an d stable compound. The effect is instantaneous. 
Ihe base that appears the most suitable for use with the antidote is carbo¬ 
nate of soda, or common washing soda,—but in clean crystals. This sub- 
