238 Experiments on the Oxygenated 
a grain of the salt, produced a number of successive 
denotations. The sulphuric acid produced flame 
with some explosions. 
EXPERIMENT XIII. WITH ROSIN. 
One part of this substance with two parts of the 
salt detonated successively when well rubbed toge- 
ther. The sulphuric acid inflamed this mixture, 
but the nitrous acid did not. 
EXPERIMENT XIV. WITH GUM ARABIC, 
- The detonations were very slight. It was mixed 
with twice its weight of the salt. .The sulphuric 
acid set fire to the mixture, but the nitrous acid 
would not. 
EXPERIMENT XV. WITH PRUSSIAN BLUE. 
No detonations whatever were produced by fric- 
tion, nor did the acids inflame a mixture of this 
substance with the salt.* 
EXPERIMENT XVI. WITH INDIGO. 
Half a grain of fine Spanish Indigo, rubbed with 
a grain of the salt, detonated successively, like the 
* Chaptal, (Elements of Chemistry, vol. ii. page 377) 
says, ‘“ Prussian blue takes fire more easily than sulphur, 
and detonates strongly with the oxygenated muriat of pot- 
ash, (Quere, did he not make use of indigo here ?) 
