Oct., 1904. 



Annual Report of the Director. 



271 



of lines connecting the specimens, after the manner previously em- 

 ployed with much success in the metallurgical collections. Adjoining 

 cases contain specimens of the larger groups of clays, such as fire clays, 

 white-burning clays, red-burning clays, and calcareous clays. These 

 are in turn sub-divided according to localities and varieties. Since 

 the most important uses of clays depend upon the properties of 

 the burnt material, there was prepared from each clay, so far as 

 possible, a burnt briquette about two inches square and one-fourth- 

 of an inch thick. These show color and texture of the burnt product, 

 shrinkage, warping, and other important phenomena. They are ex- 

 hibited in each case in connection with the corresponding clays, thus 

 enabling the properties of the burnt and raw material to be studied at 

 the same time. The number of briquettes prepared for this purpose 

 was 140. Acknowledgments are due Mr. John J. Moroney of Chi- 

 cago for assistance in their preparation. Occupying another case 

 in the hall are substances allied to clay in composition, including 

 especially ochers, fuller's earths, talcs, and meerschaum. Another 

 collection illustrates the effect of various ingredients upon clays. The 

 collection of soils shown in the same hall has been much improved and 

 enlarged, especially by the addition of a classified series of about 

 forty soils and subsoils donated by the United States Department of 

 Agriculture. With this addition the collection illustrating varieties 

 of soils has become a fairly complete one. The composition of 

 soils, their origin, and plant foods are also illustrated by collections. 

 The collections of sands and cements have not been especially 

 enlarged, since the space available for them is limited at present. 

 In Hall 72, devoted to ores of the precious metals, a complete re- 

 arrangement of the upright floor cases has been made in order to pro- 

 vide additional exhibit space and give better lighting of the specimens. 

 This has been accomplished by turning the cases at right angles to 

 their former positions, thus making alcoves in which the material has 

 been installed. A considerable rearrangement of specimens and 

 photographs was performed in connection with this work. A case of 

 abrasives has been added to Hall 78, and an additional large wall case 

 provided in the same hall for exhibiting the series of salts of soda, 

 potash, lime, etc., which had outgrown its former space. The abra- 

 sives shown include the extensive series of garnets and corundums 

 collected by the Assistant Curator in the Southern States, and 

 specimens of tripoli, silica, chalk, etc., obtained from various sources. 

 In Hall 64, the interiors of all the wall cases have been painted, and the 

 specimens which occupied them cleaned and reinstalled. A collec- 



