Scientific Intelligence . — Botany. 19$ 
after the eruption, are exhaled in great quantity, and act dele- 
teriously on animals and vegetables, but at length entirely disap- 
pear. The permanent moffettes, again, are known to have con- 
tinued for ages, as is the case in the Grotto del Cane near Ve- 
suvius. Similar permanent exhalations occur in other quarters. 
In the great stream of lava, which extends from Clermont to 
Royat in Auvergne, there are many caves and caverns, of which 
the most celebrated are the caves of Montjoly. In many of 
these, the same phenomena occur as in the Grotto del Cane at 
Naples. Similar caves occur in volcanic hills in the Vivarais ; 
and it is probable, that the irrespirable gases, which occur in 
the caves of Ribar, near Newsohl in Hungary, are of the same 
general nature. 
16. Brown Hematitic iron-ore found around Cast-iron Pipes . 
— On examining a set of cast-iron pipes, which had lain for some 
years in the line of one of the streets in the New Town of Edin- 
burgh, we were surprised to find the sand in which they had been 
laid, where in contact with the pipes, very compact and brown 
in colour. On breaking some of the masses, we found the con- 
necting matter to be brown iron-ore, and in cavities of the com- 
pacted sand, this brown iron-ore exhibiting that particular lustre 
approaching to adamantine, and the reniform shape with the 
granulated surface of brown hematite. Here, then, we have an 
instance of the formation by the action of percolating water on 
the iron of the pipes, of an ore of iron which some observers ar- 
range with the igneous mineral formations. 
BOTANY. 
17. Presence of Oxalate of Lime in the Mineral Kingdom ; 
and the Existence cf the same Salt in great quantity in 
Lichens. — M. Braconnot, some time ago detected, in a yellow 
mineral substance which he found in the cavity of a limestone 
rock near to Nancy, a considerable portion of oxalic acid ; and 
M. Rivero has described a mineral under the name Humboldtine, 
which is a compound of 53.56 protoxide of iron, and 46.14 
oxalic acid. Braconnot had already shewn that lichens abound 
in calcareous earths, which he supposed was, in them, combined 
with a particular vegetable substance. Very lately, however, he 
VOL. XIII. NO. 25. JULY 1825. N 
