Davy — On Properties possessed by Salts of Fulminic Acid. 183 



XXYII. Ox SO^E KEWLT OBSERVED PnOPEETIES POSSESSED BY CEKTATN- , 



Salts of FrLiiixic Acid. By Edmuxd W. Davy, A. M., M. D., Pro- v 

 lessor of Forensic Medicine, Royal College of Surgeons, Ireland. 



[Eead January 11, 1875.] 



The salts of fulminic acid, or the fulminates, have not received the 

 attention which the interest arising fi^om their extraordinary proper- 

 ties would lead us to expect. Tliis is, no doubt, clue in a great mea- 

 snre to their being such highly explosive and consequently dangerous 

 compounds, which have already occasioned several serious and even 

 fatal accidents to individuals whilst making them objects of research ; 

 they are, therefore, considering the amount of personal danger attend- 

 ant on a study of their properties, not veiy inviting subjects of 

 inquiry, and necessitate the exercise of much caution on the part of 

 those engaged in their investigation. 



The compound which is known to chemistB under the name of ful- 

 minic acid, and which is expressed by the empirical formula HaColS'sOs, 

 though it has never yet been isolated or obtained in the free state, is 

 capable, as is well known, of forming a number of simple and com- 

 pound salts, which are endowed with more or less explosive proper- 

 ties. Of those salts, by far the most important is the fulminate of 

 mercury, which constitutes, as is well known, the active constituent 

 of the percussion caps, and of the detonating matters which are used to 

 fire the charges in our guns and pieces of ordnance ; and for those 

 purposes it is now manufactured in large quantities, and forms a veiy 

 important instrument of modern warfare, since by its employment the 

 use of flint and steel, matches, and other rude means of firing small and 

 large guns have been quite abandoned, at least among all civilized 

 nations. 



"\\Tiilst making some experiments on the fulminate of mercury, I 

 observed that when that salt and the fcrrocyanide of potassium, both 

 in aqueous solution, arc gently heated together, the mixture at first 

 acquires a faint reddish yellow tint, which quickly passes into a port- 

 wine or deep purple colour, without the separation apparently, at 

 least at first, of any gas or solid matter. The development of this 

 coloration, under the circumstances stated, being considered very 

 singular, and hitherto unnoticed (as far as I have been able to ascer- 

 tain), led me to study the matter more closely, to determine the nature 

 of this coloured compound, and of the changes taking place in its for- 

 mation. 



On prosecuting this inquiry, I further ascertained that when the 

 purple compound was fully developed, if the heat was continued for 

 some time, or more quickly if the temperature was raised to, and 

 maintained at the boiling point, the purple colour gradually dis- 

 appeared, the liquid acquiring a light yellow tint, whilst more and 

 more of a reddish brown solid matter (which was ascertained to be the 



