1074 Scientific News. [December, 
on an arm which is clamped under the collar of the draw-tube, 
and carries a second movable arm resting in a collar to support 
the camera. This armis held in place by a thumb-screw, and it 
may be set at any point on the vertical rod. When the Zeiss a.a. 
objective is used, and the camera is lowered as much as possible, 
an image magnified about three diameters is projected on to the 
paper, and any amplification greater than three diameters may be 
obtained by varying the height of the camera, and by the use of 
the higher objectives. 
SCIENTIFIC NEWS. 
— One of the most remarkable salt formations in the world is 
located on the Isle of Petit Anse, Southwestern Louisiana, 125 
miles due west from New Orleans. It is owned by the Avery 
family. This singular salt deposit is sufficiently unknown to 
bear the light of a more thorough investigation than it has had. 
The deposit is pure crystal salt. So far as it has been traced, 
there are 150 acres of unknown depth, explored 140 feet down. 
The surface of the bed undulates from one foot above to six be- 
low tide-level. The earth covering the salt ranges from ten to 
points, tomahawk heads, paint pots, mortar and pestle and_pot- 
tery of all kinds. The dip of the salt is eight degrees. There 
is a deposit of pink sandstone quite decomposed, a coal forma- 
tion thirteen to seventeen feet thick and seventy-two per cent 
carbon, the lignite cropping out a hundred feet above the sea. 
Over the salt come pink and yellow clay beds, then the sand- 
stone and then the clay, each stratum trending towards the 
no ere are also sulphur springs. The salt is a con- 
glomerate mass of crystallizations, which in the mine look like 
dark salt, but when exposed to the light are seen to be wai 
By analyses the salt is 99,48; per cent pure; the remaining 35 1S 
made up of sulphate and chloride of calcium. The position 
of the salt shows it to be older than the coal and sandstone 
mporary pre- 
1862 while a 
n Davis and 
by a N 
l 
