CHEJIICAL SELECTIOX OF MOTHERS. 81 



c. c. and the subsequent covering with diluted sulphu- 

 ric acid, or the heating in the sand bath, were as usual. 

 The latter, however, is composed of two circular 

 plates, A and B (Fig. 30), of sheet iron covered with 

 sand. To these plates a rotary movement is given; to 

 one of them direct from a train of wheels like a clock 

 movement, and to the other by means of an endless 

 chain; both move with the same velocity. Underneath 

 these circular disks is arranged a series of gas jets; 50 

 flasks can be at once heated in this manner. The work 

 is so conducted that the flasks upon one of the disks 



FIG. 30. Heating flask revolving machine. 



are nearly empty, while those on the other are almost 

 full. Each flask, as may be imagined, is numbered. 



The analyzing apparatus is composed of a stand 

 with a central vertical support, upon and around which 

 five horizontal arms can revolve. These arms serve 

 for holding the test tubes and burettes, the former con- 

 taining the copper solutions, etc., and the latter the 

 invert-sugar solutions. The lower horizontal arms 

 just mentioned are covered with wire gauze, upon 

 which rest the ends of test tubes; each arm can 

 hold five tubes. In the second series of arms are holes 

 in which the test tubes are placed, and held in vertical 

 position. The upper series of arms hold the burettes 

 directly over the tubes containing the Violette solu- 

 tion. The operator places in front of him one of the 



6 



