320 ANNUAL OF SCIENTIFIC DISCOVERY. 



The specimen was a white crystalline solid, formed by the union of two 

 layers of salt, as often results from the evaporation of a saline solution, when 

 the pellicle formed on the surface falls to the bottom. Along the line of 

 junction crystal facets are seen, but the forms are indistinct. These crystals 

 readily scratch calc spar and dissolve without residue in water, affording a 

 solution, which, by evaporation at 150 deg. F., leaves the salt, with some of 

 the original physical characters. In this climate, the specimen attracts 

 moisture, and therefore has not a fixed amount of water constituent. 



It consists of water, sulphuric acid, soda, magnesia, chlorine ; mixed with 

 it, are traces of crenate of iron and lime, with sand and grains of earth. 



Three fragments from different masses were taken, and the following sub- 

 stances found : 



I. II. III. 



Water 1642 18-84 19-60 



Sulphate of Soda 48-00 45-82 45'74 



" Magnesia 34-20 3319 33'31 



Chloride Sodium 1'21 1-79 1-16 



Crenates Lime and Iron with Silicic Acid 0-17 0-30 013 



Sand 0-00 0'06 0'C6 



100- 100- 100- 



The varying amounts of water given are illustrative of the absorptive power 

 of the salts, in the atmosphere of this place. Dried at 90 F., the amount of 

 water was 15'20 in 100 parts, which exceeds by 4 parts the proportion neces- 

 sary to form proto-hydrates of the two salts present. 



Analysis does not show the two sulphates to be in definite proportions in 

 the masses, but the crystals may be a double salt, composed of one equivalent 

 of sulphate of soda and one equivalent of sulphate of magnesia ; each retaining 

 an equivalent of water. In the masses, the closest approximation is 42 parts 

 of sulphate of magnesia found, instead of 46 parts, required. 



The communication of Mr. Bishop embraces interesting facts. These saline 

 deserts cover extended areas in different parts of South America, and so far as 

 he has been able to learn, the saline matter differs in kind at the different 

 points. The tendency of saline matter contained in any soil is to rise through 

 the aid of moisture to the surface, when, the water escaping, the salt is depo- 

 sited. This effect, contrary to the gravitating influence, is the most common 

 cause of deserts, and may be exerted everywhere, when the evaporation of 

 water from a given surface becomes much greater in amount than that surface 

 received in the form of rain and clew. The cultivation of saline deserts by 

 washing down the saline matter, exhibits the opposite action of water in 

 restoring fertility, and it is by no means essential that the water should con- 

 tain organic matter to ensure the full effect, as the soil of deserts generally 

 contains all the organic matter of many years' accumulation. 



ON THE DISCOVERY OF VOLCANIC CINDERS AT THE BOTTOM 



OF THE ATLANTIC. 



The specimens from the bottom of the Atlantic obtained by the U. S. steamer 

 Arctic, in her recent deep-sea sounding expedition, between the coasts of 



