DESK ARRANGEMENTS. 25 



vacuum connections, so that materials may be distilled in vacua 

 as well as under atmospheric pressure, and a double stopcock for 

 the extraction of samples without interfering with the vacuum is 

 attached. Xext to this still stands a large extraction apparatus 

 consisting of a boiler of 140 liters' capacity for the solvent. From 

 this and extending to the extreme top is the exit tube connect- 

 ing with the condenser, which is at the highest point; below this 

 and between it and the still is mounted a receiving drum for the 

 condensed solvents, and farther down and to one side is the extrac- 

 tion apparatus proper. This consists of a large kettle of 100 liters' 

 capacity, steam jacketed to use heat if necessary, containing bas- 

 kets for the placing of materials, and mounted on trunnions so 

 that it may be tilted to empty and clean it. The entire apparatus 

 is fitted with vacuum which is connected with the condenser above 

 and the trunnions are so arranged that steam may be admitted 

 through them into the extractor, which is fitted with the necessary 

 safety valves to prevent accidents. A smaller still of 15 liters' 

 capacity, on the same model as the large one, is also provided. All 

 of this apparatus is of the make of Gustav Christ, of Berlin. In the 

 alcove of this room besides the apparatus given above there are 

 mounted a porcelain ball mill for the pulverizing of refractory 

 materials and a drug mill for grinding, both operated by a one-half- 

 horsepower motor with shafting and belting, a hydraulic press and 

 a vacuum drying apparatus, the latter of the make of the American 

 Vacuum Drying Company. 1 



Crossing the hall and immediately to the west of the room for 

 physics is the assay laboratory. This is provided with a large fire- 

 brick table mounted on a pier and holding the main assay furnace 

 from Braun & Co., Los Angeles, CaL, supplied with Gary hydro- 

 carbon burners, the gasoline tank being placed in the ground outside 

 the building so as to avoid all danger from fire. On each side 

 of the main furnace are smaller ones, both muffle and crucible, of 

 the Hoskins type. The main assay flue extends from these up to 

 the roof and 15 feet above the latter. The corner of the assay 

 room next the furnaces is occupied by a Braun crusher and pul- 

 verizer and a Bonnot ball mill, both operated by a 1-horsepower 

 motor with shafting and belt. In the center of the room is a pier 

 for the rolls and a large table for general work with samples. The 



1 PI. XVIII is a photograph of the commercial apparatus described above. 



