﻿Geology and Mineralogy. 233 



acicl, by which a residue of metallic silver was generally left. 

 The dissolved silver was precipitated with hydrochloric acid, and 

 in the filtrate the ammonia was determined as platino-chloride. 

 The results of sixteen analyses gave ratios which were very close 

 to three atoms of silver for one of nitrogen ; leading to the 

 formula NAg 3 . Other samples of the substance prepared by 

 warming the ammonia solution of the silver oxide on the water 

 bath, or by precipitating it with alcohol, gave the same ratio on 

 analysis. It exploded by the slightest concussion when dry and 

 requires great caution in handling even when moist. It is soluble 

 in ammonia and in potassium cyanide. — Liebig^s Ann., cxxxiii, 

 93-101, April, 1886. G. f. b. 



4. Formation of Anhydrite or anhydrous Calcium Sulphate. 

 — The formation of anhydrite has recently been held to re- 

 quire pressure — a pressure of ten atmospheres, which is that 

 of the sea at a depth of about 350 feet. Professor G. Spezia, of 

 Turin, publishes (in the Atti of the Turin Academy, vol. xxi, 

 1886) the following results of experiments by him. The action 

 of aluminum sulphate on powdered apophyllite under a pressure 

 of 300 atmospheres for three months produced gypsum instead of 

 anhydrite. The same was the result from a piece of calcite kept 

 in a solution of copper sulphate under 95 atmospheres for three 

 months. He obtained from the reaction of magnesium sulphate 

 with calcium nitrate diffused in water, and in another trial dif- 

 fused in a saturated solution of sodium chloride, under pressures 

 of 100 and 500 atmospheres, in both cases only gypsum. From 

 these and other similar experiments here mentioned he concludes 

 that some condition besides that of pressure is required to produce 

 anhydrite. The author alludes to methods of obtaining anhydrite, 

 citing G. Rose's results, that gypsum heated to 120°-130° C. in 

 a saturated solution of sodium chloride changed to anhydrite, 

 and that at a lower temperature the reverse took place. 



II. Geology and Minekalogy. 



1. Volcanoes of Japan ; by John Milne (Trans. Seism. Soc, 

 Japan, ix, Part II. Yokohama, 1886. 184 pages, 12mo, with 

 maps and plates). — Mr. Milne gives, in this long and valuable 

 memoir, an account of the many volcanoes of Japan and the ad- 

 joining islands, from historical documents and to some extent 

 from personal observations, and illustrates the subject by a map 

 showing their distribution, and by plates containing views of 

 many of the volcanic cones. The highest of them is the noted 

 Fuji-san (=Mount Fuji), by outsiders usually called Fujiyama, 

 near Yokohama. The altitude, deduced from many observa- 

 tions, is between 12,400 and 12,450 feet. It is generally reported 

 to be extinct; but Mr. Milne in an ascent in 1880 saw some 

 steam issuing just outside of the pit of the crater. Of the other 

 volcanic peaks, one (Norikurayama) is 10,447 feet high; Mitake 

 is 10,000 feet; three are between 9,000 and 10,000 ; two between 



