ON A NEW BORATE OF SODA. 
177 
plain the formation of boracic acid from the behaviour of 
borax towards chloride of ammonium. 
Among recent chemists, Payen has especially devoted 
attention to the formation of native boracic acid. As is 
well known, it has hitherto only been found in Tuscany, in 
the neighbourhood of Sienna, near Castelnuovo and Sasso, 
and on the island Volcano; in both places in a volcanic 
district, and at both localities accompanied with hot vapours 
which rise from the earth. Payen explains the formation 
of the boracic acid by assuming that strata of sulphuret of 
boron occur at some depth, which are decomposed by the 
percolating water of the ocean, producing boracic acid and 
sulphuretted hydrogen. Part of the boracic acid sublimes, 
forms precipitates, and reaches the lagoons; part of it decom- 
poses the salts contained in the sea water, and the carbo- 
nate of lime of the rock thereby liberating carbonic and 
muriatic acids, &c. This is one hypothesis founded upon 
another; it assumes the existence of a substance, sulphuret 
of boron, which has never been found hitherto ; and the 
possibility of its being formed in nature, to judge of its arti- 
ficial preparation, presupposes a rare coincidence of favour- 
able conditions. 
I have found that boracite and datolite, which are borates 
of magnesia and lime, behave precisely like borax towards 
chloride of ammonium, liberating ammonia. But there are 
several minerals besides these and tinkal which contains 
boracic acid, for instance tourmaline, axinite, &c. Now, 
in a volcanic district, where the occurrence of native sal- 
ammoniac is quite usual, it merely requires the presence of 
any such mineral, and the conditions requisite for the pro- 
duction of boracic acid are given. When an excess of 
chloride of ammonium is present, the borax is entirely de- 
composed into chloride of sodium and boracic acid; and the 
same is undoubtedly the case with the other compounds of 
boron. The ascent of the boracic acid with the hot va- 
pours is readily explained, from the known property of 
