Jan., 191 7. Annual Report of the Director. ioi 



stone and iron-stone meteorites were placed, the specimens being 

 grouped so as to bring those of the same class together. At the same 

 time the opportunity was improved to definitely group all the meteor- 

 ites, the grouping being on the basis of a classification founded on 

 structural features. In Hall 31a number of series have been rearranged 

 with or without the addition of new material. One of these is a collec- 

 tion of volcanic products which has been so reorganized as to exhibit 

 the characteristic products of each locality in groups. At present, 

 good series of the products of the volcanoes of Vesuvius, Popocatepetl, 

 Kilauea, Sakurijima, the Auvergne region and many localities in the 

 western United States are shown. A special addition made to the 

 products of Vesuvius was a series of specimens of volcanic ash thrown 

 out during the eruption of April, 1906. These specimens show the 

 changes in the character of the ash during successive days of the erup- 

 tion. Photographs of a recent eruption of Sakurijima were installed 

 among the products of that volcano. Other additions made to the 

 series of dynamical geological products in Hall 31 include six splendid 

 specimens of zonal weathering which were collected by the Curator in 

 Maine, specimens of dendrites similarly collected, a number of speci- 

 mens of cone-in-cone structure, stylolites, etc., collected by the Curator 

 in Illinois, and a number of specimens showing several varieties of 

 weathering. Another change made in the installation of this hall was 

 the removal to storage of the series of New York rocks and the installa- 

 tion in its place of collections illustrating the uses of lime and of borax. 

 In the collection illustrating lime and its uses, a number of varieties of 

 limestone and lime from various localities are shown and following these, 

 illustrations of chemical and agricultural uses of lime and limestone, uses 

 of lime for paints, plasters, and cements, medical uses of lime, etc. In 

 the borax collection are shown various borax minerals, various refined 

 boraxes, and illustrations of the uses of borax in the arts. Another 

 collection prepared and installed in this hall was one illustrating sources 

 and uses of potash. Various rocks and minerals containing potash in 

 appreciable quantities are exhibited in this collection and many of the 

 finished products from these rocks, including not only potash but 

 alumina, sulphuric acid, etc. The collection illustrating magnesia and 

 its uses was considerably enlarged and rearranged, additions of Indian 

 and Grecian magnesite, raw and calcined, being made, also of metallic 

 magnesium, hydraulic cements, magnesia packing, etc. To the sulphur 

 collection were added some interesting specimens of molded sulphur 

 received from China. Some additions were also made to the economic 

 barite and fluorite collections. A magnetic compass was installed in 

 connection with the large specimen of lodestone in Hall 30, the compass 



