VIII. TEACHING (PURE). 671 



2442. Drawings, two, illustrating the making of coal-gas, 

 used for teaching chemistry in the Secondary Schools. 



I. Coal-gas factory. 



II. Regulator of coal-gas factory. 



Dr. I), de Loos, Director of the Secondary Toicn School, 

 Lei/den. 



2452. Model of the Chemical Laboratory of the Secondary 

 Town School, Leyden. Constructed by J. Noest, custodian of 

 the building. 



Dr. D. de Loos, Lecturer on Chemistry, and Director of the 

 Secondary Toivn School, Leyden. 



A. Forcing-pump. The pump fills a large cistern in the upper part of the 

 building. This cistern discharges its contents into the white pipes, and 

 supplies the laboratory and the other parts of the building with water. The 

 red pipes carry off the drainage from the laboratory into a sink constructed 

 below the surface. The large black pipes, as also the small ones over the 

 pupils' work-tables, are the gaspipes. 



B. Register-school. 



C. Chimney with three passages ; one to conduct off the smoke of the 

 stove, the others to carry off the bad gases disengaged in chemical operations. 



D. Pump for rain-water and well-water. 



E. Cupboards for twenty-two pupils, in which they keep the re-agents ; the 

 largest, which is open, is for the use of the lecturer on chemistry. 



F. Drawer for small apparatus, as spoons, glass tubes, &c. 



G. Small cupboards for the use of the pupils, in which to keep chemical 

 preparations still in progress. 



H. Bunsen's pump to filter under a lesser pressure. The water, running 

 through the red pipe from the top to the bottom of the laboratory, carries the 

 air from the bottle along with it. 



I. Entrance to the balance-room. 



K. Collection of implements for performing chemical experiments. 



L. Large cupboard for chemical preparations and apparatus. 



M. Table with apparatus for blowing glass. 



2455b. Case containing five stands and a collection of 

 spheres made to demonstrate the structure of chemical 



combinations according to the theories of A. W. Hofmann. 



Manuel Gonzalez, Madrid. 



2453. Diagram of Carre's Ice-making Machine, by Mr. 



Hubertus Sattler. Dr. Alexander Bauer, Vienna. 



Adapted to be used for making experiments at lectures on technical chemistry 

 to small audiences. 



24O8. Apparatus for exhibiting in the lecture room the con- 

 traction which takes place when oxygen is changed into ozone. 

 It is a modified Siemens' tube ; the contraction being shown by 

 the ascent of the sulphuric acid in which the open end of the tube 

 is immersed. Dr. Andrews, F.R.S 



