XVII 



MOLECULAR ARCHITECTURE 



391 



substances were all neutral. Five acids (mucic, oxalic, 

 tartaric, citric, acetic) contained an excess of oxygen. Four 

 resinous and oily substances (resin, copal, wax, olive-oil) 

 contained an excess of hydrogen. 



5 DECIMETRES 



FIG. 49. GAV-LUSSAC AND THENARD'S APPARATUS FOR THE COMBUSTION OF 

 ORGANIC COMPOUNDS. 



The tube A A', of hard glass, 20 cm. long and 8 mm. wide, carried a side-tube 

 JSB', leading into a trough of mercury. A copper cap CC', cemented to the top 

 of the tube A A', carried a glass tap DD' (shown on a larger scale as an inset) 

 and a cup of broken ice Ff, to prevent the grease on the tap from melting down 

 into the hot tube. The tap DD' was not pierced in the usual way, but had a 

 small cavity, in which a pellet could be inserted, and dropped into the hot tube 

 without opening it to the air. Several pellets were burnt to displace the air 

 from the apparatus, and the gases set free by burning a known weight of the dry 

 pellets were then collected, measured and analysed. 



Berzelius (1815) assigns formulas to organic compounds. 



In 1815 Berzelius described a new series of organic analyses 

 which he carried out " in order to determine how far the 

 laws which I had established in inorganic nature could be 



