28 CHEMICAL DISCOVERY AND INVENTION 



narrow lead pipe to several places where it is required in other 

 rooms. 



This is an appliance of a different character from the mercury 

 pumps, which are capable of giving a really high vacuum, such as 

 would be necessary in experiments on the electric discharge 

 through gases and for other purposes to be described later in the 

 book. 



In the laboratory for organic chemistry the chief modification 

 in the arrangements of the working tables is in the direction of 

 giving more space to each student. Instead of 5 feet from side 

 to side as in the analytical laboratory, 7 feet are allowed, and 

 between each block of work tables there is a narrow operation 

 table, covered with lead, and supplied with gas, water, and steam 

 taps. Here distillations may be conducted as well as any other 

 operation which requires an extended train of apparatus. The 

 operation table has a raised edge so that in the event of accident 

 any liquid spilt will not run to the ground, but may be swept 

 down a central channel to the drain. This is necessary in view 

 of the fact that volatile and inflammable liquids are so frequently 

 used in this class of work. 



In this laboratory, the floor of which is about 35 feet from the 

 ground, reduced atmospheric pressure is obtained (for distilla- 

 tions or filtration) by the use of Sprengel water-pumps ; the fall 

 pipes consisting of narrow composition gas-pipe, and necessarily 

 more than 30 feet long, are carried down outside the building to 

 the ground, where they discharge into the drain. 



The fume chambers in this room are similar to those in the other 

 laboratories, with the addition of cupboards below closed by sliding 

 iron doors. In these spaces are placed the iron boxes in which 

 sealed glass tubes can be safely heated. If an explosion occurs 

 rom the bursting of one of these tubes no damage will be 

 done. 



Another everyday requirement in the organic chemistry 

 laboratory is a supply of ice and an ice chest. For the former a 

 means of crushing it will be necessary where there are many 

 workers, and one of the machines designed somewhat like a large 

 coffee mill serves the purpose. 



The staff of the CHEMICAL DEPARTMENT at South Kensington 

 is as follows : 



1 Professor of General Chemistry. 

 1 Professor of Organic Chemistry. 



