m. schonbein’s test for hydrocyanic acid. 
593 
the leaflets smooth, very slightly petiolate, ovate with a crenate margin, the 
crenations being larger at the apex, and ceasing towards the base, and about 
an inch and a half long, the terminal one being the largest. These I have 
compared with the two species of Amyris notified by Heller, as yielding the 
Lignaloe oil, but they do not agree. They are, however, clearly those of a 
species of JEla/phrium (Bursera), and M. U. Baillon, to whom Professor Oliver, 
of Kew, referred them, remarks that they have the appearance of those of 
JE. graveolens, of Kunth. I trust, however, before long to obtain flowering 
specimens of the tree or trees, and as soon as they have been determined, to 
communicate the result. 
DESTRUCTIVE EXPLOSION OE PICRATE OF POTASH IN 
PARIS. 
An explosion of a most disastrous character occurred in Paris on Tuesday, 
the 16th of March, in the laboratory of M. Fontaine, manufacturing- 
chemist, the successor of Messrs. Robiquet and Pelletier. It appears, from 
what is known on the subject, that a quantity, equal to about 56 lbs., of picrate 
of potash was being packed for transmission to Toulon, to be used in charging 
marine torpedoes, when, from some unknown cause, an explosion took place 
which destroyed the premises, and caused also destruction of human life, in¬ 
stantly killing all those who were present, and who might have explained the par¬ 
ticular circumstances of the case. 
The explosive compound which occasioned this great calamity was a salt of 
picric acid, which has frequently been used as a dye, imparting a yellow colour 
to silk or wool without requiring any mordant or previous preparation of the 
fabric to be dyed. 
It has long been known that the salts of picric acid are explosive, the acid 
itself being a compound having a similar constitution to gun-cotton, and being 
usually made by the action of nitric acid on carbolic acid. Some years ago a 
factory in Berlin was destroyed, and three men killed, by the explosion of 
40 lbs. of picrate of soda. This salt is said to explode with four times the force 
of gunpowder. 
The application of salts of picric acid for the production of implements of 
war appears to have been of recent date, and the terrific nature of the explo¬ 
sion which has now occurred in Paris fully justifies the opinion formed of their 
applicability for that purpose. It is stated that a few pounds of picrate of 
potash, enclosed in a torpedo, explodes with sufficient violence to destroy an 
iron-clad frigate. The order that was being executed by M. Fontaine was re¬ 
ceived from the Minister of Marine ; and it is surprising that the Government, 
knowing the dangerous nature of the material, should have allowed such an 
order to be executed in Paris, where an accident could hardly fail to prove fatal 
to many persons. The victims on this occasion were M. Fontaine’s son, M. 
Bal, a chemist, and two other persons employed in the establishment, but be¬ 
sides these, most of whom were literally blown to atoms, there were several 
other persons more or less seriously injured, and a great deal of property de¬ 
stroyed or damaged. 
REMARKS ON M. SCHONBEIN’S TEST FOR HYDROCYANIC 
ACID. 
BY MR. GEORGE WELBORN. 
I have made some experiments with papers, pr 
YOL. X. 
epared according to M. Schon- 
% 2 s 
