January 15, 1886.] 



SCIENCE. 



61 



heat received in twenty-four hours from the sun 

 on the summer solstice is not greatest at latitude 

 23£°, where the sun is vertical, but has two 

 maxima farther north, — one at 43° ; the other 

 and greater at the pole, with a faint minimum 

 at 66° ; because the sunshine at the pole through 

 twenty-four hours, at a constant altitude of 23£°, 

 is greater than the sunshine in the twelve- hour 

 day at the tropic, with the sun vertical only at 

 noon. But this gives a very erroneous idea of the 

 temperatures at these latitudes. Now, on the as- 

 sumption that two or three tenths of a vertical 

 ray are absorbed by the atmosphere, An got finds 

 the maximum of heat received at the bottom of the 

 atmosphere on the solstice has its maximum at 

 35°; farther north, the heat received diminishes 

 continuously to the pole, rapidly at first, then 

 slowly beyond the polar circle ; and this is fairly 

 conformable to the distribution of temperature. 

 An interesting calculation shows, that, on account 

 of our less distance from the sun in December 

 than in June, the latitude circle about 24° north, 

 and not the equator, receives the same amount of 

 heat on the two solstices : the equator, therefore, 

 belongs in this respect to the southern hemisphere. 

 The memoir is illustrated by an instructive series 

 of curves showing the distribution of heat over 

 the earth at numerous dates. W. M. D. 



SODA AND POTASH IN THE FAR WEST. 



In view of the large quantities of soda and pot- 

 ash in various forms that are imported into this 

 country, it is surprising that the abundant sup- 

 plies of these alkalies within our own borders are 

 not more extensively utilized. 



It is probably known to all American geologists 

 that there are extensive deposits of the chloride, 

 sulphate, anc 1 carbonate of soda at many points in 

 the arid regions of the far west, which may be 

 had for the trouble of gathering. These deposits 

 occur in the desiccated beds of ancient lakes in 

 Nevada, Arizona, western Utah, and portions of 

 California and New Mexico. There are certain 

 lakes, also, which are valuable brines. 



In the basins where evaporation has been nearly 

 or quite complete, the alkaline salts occur either 

 at the surface, when they appear like fields of 

 snow frequently many square miles in extent, or 

 they may be concealed beneath the layers of fine 

 mud known as playa deposits. Again, large areas 

 in Nevada and Arizona are white with alkaline 

 salts that have been brought to the surface in solu- 

 tion, and deposited when the waters evaporated. 

 These efflorescences are frequently rich in sodium 

 carbonate, sulphate, and borate, and have been 

 utilized to a limited extent at a few localities. 



The lakes of the far west which are likely to 

 become of commercial value on account of the 

 alkaline salts they contain are Great Salt Lake, 

 Utah ; the Soda Lakes, near Ragtown, Nevada ; 

 Mono and Owen's lakes, California ; and Summer 

 and Abert lakes, in Oregon. All of these are 

 without outlet, and owe then high percentage of 

 mineral matter to the concentration by evapora- 

 tion of the waters of streams and springs with 

 which they are supplied. Their chemical compo- 

 sition is shown in the following table : — 



Constituents. 



Sodium (Na) 



Potassium (K) 



Calcium (Ca) 



Magnesium (Jig) 



Lithium (Li) 



Chlorine (Cl) 



Bromine (Br) 



Carbonic acid(C0 3 ). 



Sulphuric " 

 Phosphoric" 

 Nitric " 

 Boracic " 

 Silica (Si0 2 ) , 

 Alumina (Al o 0„) 



Total parts per thousand 149.936 113.647 



(S0 4 ).... 

 (HP0 4 ). 

 (N0 3 )... 

 (B 4 7 ).. 



Z 



49.690 

 2.407 

 0.255 

 3.780 

 traee 



83.946 

 trace 



40.919 

 2.357 



0.245 

 40.851 



16.854 

 11.857 



0.286 

 0.278 



18.100 

 1.111 

 0.278 

 0.125 



11.610 



11.465 

 6.520 



0.153 

 0.268 



bo 



il 



21 650 

 2.751 

 trace 

 trace 

 trace 



13.44'J 



13.140 

 9.362 

 trace 

 trace 

 trace 

 0.164 

 trace 



2.773 

 10.637 



0.(02 

 8.220 



4,547 

 0.49"' 



60.507 26.740 



1 Analysis bv Prof. O. D. Allen, U. S. geol. explor. of the 40th 

 par., vol. ii. p. 435. 



2 Analysis by Dr. T. M. Chatard, Bull. No. 9, U. S. geol. surv., p. 25. 



3 Ibid., p. 26. 



4 Analysis by Dr. Oscar Loew, Ann. rep. chief of eng., U.S.A., 

 1876, p. 190. 



5 Analysis by Dr. F. W. Taylor, Fourth ann. rep., TJ. S. geol. 

 survr., 1882-83, p. 454. 



It is safe to predict that Great Salt Lake will 

 not only be of great value in the near future on 

 account of the immense quantities of common 

 salt it is capable of producing, but also for the 

 sodium sulphate it contains. When the temper- 

 ature of the lake-water is reduced to 20° F., the 

 separation of sodium sulphate takes place as a 

 flocculent precipitate, which increases in quantity 

 with decrease of temperature. This should sug- 

 gest to manufacturers a method of obtaining the 

 salt in a pure state and on a large scale. When 

 the temperature of Great Salt Lake is lowered on 

 the approach of winter, its waters become opales- 

 cent, owing to the precipitation of sodium sul- 

 phate in an extremely finely divided state. During 

 the winter months the temperature cf the air in the 

 region of the lake sometimes falls to 20° or more 

 below 0° F., and at such times the separation of 

 sodium sulphate takes place on an immense scale, 

 and it is thrown up on the shore in thousands 



