ON CYANIDE OF POTASSIUM. 
137 
Third, That when prepared in the best manner it is con- 
stantly liable to change, from causes that cannot be avoided, 
in dispensing it. 
Fourth, That the process of the U. S. Pharmacopoeia 
modified by evaporation in a water-bath is the best process 
yet proposed for preparing it. 
Fifth, That its only value with reference to prussic acid 
is the facility with which cyanide of silver is formed by its 
decomposition, as indicated in the assay of the above sam- 
ples. Moreover, I may remark that the necessity for a sub- 
stitute for prussic acid has ceased, — since the merest tyro 
can prepare that acid extemporaneously of invariable 
strength, without any apparatus except a glass vial, by the 
beautiful process of the last Pharmacopoeia.* 
Maryland Med. <§• Surg. Journal. 
* Should the muriatic acid used in the process referred to be in excess, 
(in the absence of a specific gravity measure,) it will only tend to pre- 
serve it ; and if the chloride of silver is lost, the result is less expensive 
than the commercial prussic aci<J, 
