88 The Mickoscope. 



the sea level. In Spain, 16 leagues from Barcelona, there is a 

 mountain of salt three miles in circumference and 500 feet high. 

 It is quite pure. No gypsum is found with it. This mineral has 

 been found also in considerable quantities in New South Wales. 



It has long been known that rock salt existed in very large 

 quantities in Nevada and Arizona. On Holt's map of Calfornia and 

 Nevada, published in 1876 a deposit in Lincoln county, Nevada, is 

 described as being five miles long and 600 feet high. This locality 

 lies 53 miles, by the scale of the map, a little west or north from 

 Callville, on the great bend of the Colorado Rivei*. Some years ago 

 I examined specimens and found them to be very pure. 



In Cleveland's " Mineralogy," published in 1816, I find a state- 

 ment that " rock salt is found in California in very solid masses." 

 The writer probably referred to the peninsula of Lower California. 



In the sink of the Colorado desert in San Diego county, deposits 

 of salt have been discovered, and are rather extensively worked, but 

 this salt is probably the result of the evaporation of the waters of an 

 ancient inland sea, cut off from the great ocean by the delta of the 

 Colorado River, or by an upheaval of land, gradual or otherwise. 

 The water, under the influence of the sun and the dry climate of the 

 locality, became less, until a resulting small lake of concentrated 

 seawater finally dried and left the deposit of salt. This is a good 

 theory until a more thorough study of the deposit is made. It is 

 now covered by silt and debris washed down over it during many 

 winters of rain-storm and cloud-liurst. 



The associate minerals often found with rock salt have also 

 great value. Chloride of potassium in very large quantities is 

 extracted from beds overlying the salt deposits at Stassfurt, in Sax- 

 ony. Some idea of the quantity may be inferred when the state- 

 ment is made that in 1863-64, 400 tons of carnallite were raised. 

 The yield increased annually until 1875, when the production was 

 494,414 tons. Carnallite contains theoretically 26.88 per cent, of 

 chloride of potassium. 



If a deposit of this character should be discovered in connection 

 with one of our great salt deposits, its importance to California and 

 the Pacific Coast can scarcely be estimated. 



Mr. Hanks illustrated his essay with specimens which were 

 examined under the microscope, and found to bear out well the 

 descriptions in the paper. The study of the specimens led to an 

 interesting discussion of the subject. 



Edward J. Wickson, 



Recording Secretary. 



