50 EEPOET OF THE SECRETARY. 



has also prepared a catalogue of tbe building stone collection uow in tbe 

 Museum, which will be published in the Museum report for the coming 

 year. He has also in preparation a general work on economic petrog- 

 raphy for the use of students, quarry men, architects, and builders. 

 The curator calls especial attention to the desirability of allowing the 

 head of the department annually a certain sum of money to be ex- 

 pended in filling ga^js in the exhibition series. 



The total number of rock specimens in the collection is given as 

 20,647, 17,647 of which belong to the reserve series. Of the latter 

 number, 5,313 are on exhibition, 2,730 of which are building and orna- 

 mental stones, and 1,829 belong to the educational series and rock- 

 forming minerals. 



XVIII. Department of Metallurgy and Economic Geology. — The atten- 

 tion of Prof. F. P. Dewey, curator of this department, has been devoted 

 to classifying and arranging the mass of unassorted material which has 

 been referred to in previous reports, especially the material received 

 from the Institute of Mining Engineers, part of which was received 

 during the year. It has not been the policy of the department to solicit 

 accessions, owing to the fact that there is so much material already on 

 hand which, owing to the lack of space, it has been impossible to bring 

 under control. During the year work upon the preparation of the ex- 

 hibition series has gone steadily forward, and as soon as the exhibition 

 cases shall have been provided a large amount of material can be dis- 

 played. A preliminary display has been made of a portion of this collec- 

 tion, especially the systematic collection, the beginnings of which were 

 exhibited at I^ew Orleans. This material exhibited at New Orleans 

 was intended to illustrate (1) the geological distribution of the ores of 

 the United States and (2) the processes used in the extraction of the 

 metals from the ores. A descriptive catalogue of the systematic col- 

 lections has been jjrepared by the curator for publication in the Mu- 

 seum report during the coming year as a guide for visitors and as a 

 foundation for future collections. 



The curator has for three years been engaged upon the investigation 

 of the physical properties of coke, and has already published a paper 

 upon the porosity and specific gravity of different kinds of coke. In 

 the prosecution of this work the department is aided by Maj. Jed. 

 Hotchkiss, who has provided necessary apparatus. In connection with 

 this work especial attention has been paid to the devolopment of the 

 Museum collection of the ookes of the world, which is already of con- 

 sidrable extent and constantly increasing. 



The curator called attention to the especial need of the Museum for 

 special systematic collections gathered with reference to showing, first 

 the nature and the methods of occurrence of the various ores in diifor- 

 ent portions of the United States ; second, the methods of mining, and 

 third, the methods and processes of smelting. In connection with 



