174 
ON A NEW BORATE OF SODA. 
gaseous current and the ignited matter ; and further, spongy 
platinum becomes incandescent behind the paper, in the 
path of the current, if the paper be three or four centime- 
tres from the orifice, provided the metal is placed against the 
paper, or, at least a very slight distance from it. The pres- 
sure under which the phenomenon is produced does not ex- 
ceed from ten to twelve centimetres of water. To my great 
surprise, M. Louyet adds, I have established that hydrogen 
gas traverses with equal facility gold leaf and beaten silver. 
Thus surround spongy platinum with several folds of gold 
or silver leaf, and direct against it a current of hydrogen, the 
platinum will become incandescent, and the gold or silver 
will adhere to its surface. Behind leaf tin also, spongy 
platinum is, in like manner, strongly heated. Through a 
thin membrane of gutta percha, such as is obtained by 
evaporating a slight layer of it from a solution in chloroform, 
hydrogen likewise passes; but hydrogen gas does not sen- 
sibly pass through pellicles of blown gas, however thin they 
may be. — Literary Gazette. 
ART. XXXVI.— ON A NEW COMPOUND OF BORACIC ACID 
WITH SODA, AND ON THE PROBABLE MODE OF FORMA- 
TION OF BORACIC ACID. 
By Dr. P. Bolley. 
I was led to this inquiry from having frequently observed 
that, on mixing solutions of borax and chloride of ammo- 
nium, ammoniacal gas is disengaged. This fact, of which 
I could find no mention in any work, probably from its 
apparent unimportance, may be explained in two ways, 
either an exchange of bases and acids may take place, and 
borate of ammonia and chloride of sodium be formed from 
