Whirlwinds produced by the burning of a Cane-Brake. 181 
medicinal powers from the others, which contain chlorids of cal- 
____ cium and magnesium ; the medicinal action of these two salts, and 
___ especially of the chlorid of calcium, is so well marked that their 
presence ought not to be disregarded in estimating the therapeutic 
value of a minéral water ; the distinction here drawn is therefore 
one to which I would call the attention of the medical profession, 
and it may also be found that the presence of such active agents . 
as the salts of baryta and strontia, imparts peculiar medicinal vir- 
tues to the waters of Varennes and St. Léon. ; 
Montreal, May, 1849. 
Arr. XIX.— Whirlwinds produced by the Burning of a Cane- 
Brake; by Avexanper Fisuer Oiustep, A.M.—With a Plate. 
canes in an incredibly short period. They form dense thickets, 
the stems often standing but an inch or two apart, although rising 
thirty-five or forty feet. They thus constitute a barrier impen- 
etrable by man and lar 
there are occasional assages due to streamlets or some variation 
of soil. There are occasional large trees here and there in a cane- 
en ee ee ee 
* Arundinaria macro of Michaux, Ludolfia macrosperma of Wildenow. 
re is a smaller kind of cane that grows in Georgia and the neighboring states 
and forms cane-brakes equally impassable. 
+ The sugar-cane y grows from eight to ten feet. 
