xxiv GENERAL SUMMARY OF SCIENTIFIC AND 



provemcnts to be made known, but we shall in the end find 

 ourselves richer for the hard labor of the French chemists 

 during their time of need. A marked change has taken place 

 in the source of potash, iodine, and bromine. The Stassfurt 

 mines now yield the greater part of the potash and bromine 

 salts required by the world, and the Chile saltpetre appears 

 likely to compete with sea-weed as a store-house for the ex- 

 traction of iodine. 



Such are some of the most notable indications of progress 

 in the department of Chemistry, the details of which will be 

 found embodied, in a greater or less degree, in our annual re- 

 port for the year. 



In the departments of Geology and Mineralogy the princi- 

 pal progress in America has been in the way of information 

 respecting the geology of particular sections of the country 

 by the publication of various reports, such as the explora- 

 tions of Clarence King, Dr. Ilayden, Professor Marsh, and oth- 

 ers, prosecuted over a wide range of country ; by the reports 

 of geologists of certain states, as those of Michigan, Ohio, 

 New Jersey,, etc. 



From Dr. Ilayden we have a detailed report of operations 

 in Wyoming Territory, and partial accounts, to be completed 

 hereafter, of the structure of the wonderful regions in the 

 vicinity of the head waters of the Yellowstone, where, in an 

 area of about fifty by sixty miles, we have one of the most re- 

 markable exhibitions of hot springs, geysers, mud volcanoes, 

 etc., to be found on the face of the globe. 



Papers by Dr.T. Sterry Hunt on the geognosy of the Ap- 

 palachians and the origin of crystalline rocks; by Professor 

 Dana on the glacial system of the New England States and 

 Canada ; accounts of the geology of the diamond fields in 

 Africa, and new views in regard to the geology of New Zea- 

 land, are all in the list of communications for the year. 



The visit of the Swedish expedition to Greenland for the 

 purpose of bringing back a large number of meteorites has 

 been crowned with success, and a number were brought home, 

 one of them of the enormous weight of over 40,000 pounds. 

 Unfortunately, these giant specimens have been found very 

 difficult of preservation, exposure to the air of cities seeming 

 to cause them to crumble into fragments, and to render futile 

 all means employed to prevent their entire disintegration. 



