98 Morey onMineral Waters, &¢. 
tion of the pulverized marble. The best mode I have 
tried as yet, is to cause the vessel to revolve, say a stone 
jug, on an axis and end over end: and to have a portion of 
the marble coarse. As the sulphate of lime forms on ‘the 
surface of these lumps, by their friction in rolling over each 
other, it appears to be worn off, presenting continually fresh 
surface for the acid to act upon, and thereby continuing ve- 
ry regularly, its operation ever so long. These vessels may 
be made to revolve (very slowly if necessary) by weights, 
springs, or a part. of the water—or may. ee be 
moved by hand. The gas presses out at one end of this 
axis. A very cheap, quick, and agreeable mode of pre- 
paring the water, where we have (or have not) an aqueduct 
or head to resort to, is to take four or five, or more decan- 
ters, say of the capacity of a quart; fill them with fragments 
of marble—set them in a row or other form, each with a 
good cork; let a tin tube screw upon the axis to receive 
the gas, and press pieces of cork or other stuffing to the 
vessel, to make it tight around the axis. This tube, near 
the other end, is of a conical form, and turned down at a 
right angle far enough to be inserted through the cork of 
the first bottle: another tube, turned down at each end, so 
that one leg shall pass through the cork also, to the bottom 
of the first decanter, and the other through the cork of the 
second decanter; and so on with as many as are to be used. 
mall reservoir is to be placed as many feet above as 
convenient, and the first vessel, with a small pipe leading 
down and through the first cork, with an opening at ‘the 
lower end about one-thirtieth of an inch in diameter. A 
quantity of pulverized lime and water may be put into the 
revolving vessel ; then more water, containing a small quan- 
tity of clay or sulphate of lime. This will be deposited on 
the lime, so as to prevent the action of the acid when pour- 
ed in, which may now be added, and this vessel corked. 
It is now ready foruse. Put cool water into the reservoir, 
turn the vessel moderately a very little, if the gas is not al- 
ready forming fast enough. The water strikes on the first 
fragments of stone, is thrown over. them, and passes over 
the surface, from one to another, to the bottom, where it is 
continually taken up by the tube with a pertion of the gas, 
and discharged just below the cork of the second vessel ; 
or thrown out in a spray by and with the gas; or else dis- 
