670 



SCIENCE 



[N. S. Vol. XXVIII. No. 724 



to distribute the water by gravity through- 

 out the building. 



OXYGEN AND HYDROGEN" 



Hoods in which hydrofluoric acid is to be 

 generated, or silica is to be driven off by 

 that acid, should be lined with thin sheet 

 lead. The front windows may be paraf- 

 fined. 



Oxygen and hydrogen can now be con- 

 veniently produced electrolytieally in suit- 

 ably placed tanks in which the gases are 

 collected as generated, and stored. Both 

 of these gases can be laid on to the lecture 

 table and in the spectroscopic room. It is 

 also desirable to have the oxygen laid on 

 to the combustion room adjoining the or- 

 ganic laboratory. In this connection it 

 may be stated that a good safety device is 

 necessary to prevent back flash and possible 

 explosions in these pipes. This can be 

 readily accomplished by inserting a device 

 built on the principle of the Davy lamp. 

 About a meter from the final outlet the 

 pipe is increased to double its bore for 

 250 cm. and then reduced again to its nor- 

 mal size. By inserting a loose roll of cop- 

 per gauze in this enlarged portion of the 

 pipe the striking back of the flame is 

 avoided. 



LECrtlRE THEATER 



The lecture theater should be lighted by 

 skylight and provided with a horizontal 

 black curtain, electrically operated, for 

 darkening the room. On dingy days or in 

 the evenings, this room should be illumi- 

 nated by diffused light from overhead re- 

 flection of electric bulbs hidden along the 

 cornices of the room. If chandelier light- 

 ing be used, the Zalinski diffusion reflector 

 made by the Halophane Company should 

 be installed, as the best results are obtained 

 from them. 



The esthetic sense has been appealed to 

 in our lecture room and museum by placing 



in each of these large rooms four plaster 

 cornices. In the lecture room the four give 

 a mythical representation of the realms of 

 solid, liquid, gaseous and unknown forms 

 of matter. In the museum we have the 

 unknown of the past typified, the period of 

 alchemy, the period of chemistry, and the 

 celestial. A magnificent mural painting 

 pleases the eye of one who sits in the grand 

 lecture theater at the Sorbonne in Paris. 

 In our theater, one looks not at the blank 

 walls, but on the left-hand side he sees a 

 framework which carries the names of the 

 accepted chemical elements and the inter- 

 national atomic weights on movable panels. 

 In this manner, as new elements are dis- 

 covered, the panels may be shifted. As the 

 atomic weights are changed as the result of 

 our increased knowledge and more accurate 

 work, the values can be changed. It may 

 be interesting to call your attention to the 

 fact that provision has not been made for 

 more than one hundred elements, although 

 I am aware that three hundred or more 

 have been suggested. 



On the right side of the wall we have the 

 periodic arrangement of the elements in 

 panels. Immediately underneath these 

 panels are chart hangers, ammeters and 

 voltmeters thirty-six inches in diameter 

 (with illuminated scales) for both alter- 

 nating and direct currents for electric fur- 

 nace and other demonstrations. Imme- 

 diately underneath these are glass black- 

 boards with marked squares, the lines of 

 which are not plainly visible at a distance 

 in the room itself, but may be used with 

 ease by the lecturer in plotting curves. 



A suitable and separate system of illu- 

 mination for the blackboards should be 

 provided. 



In my opinion, a lecture room should not 

 be constructed to seat more than 250. The 

 size of the room is so great when a larger 

 niimber is taken care of that those sitting 



