129 



Mr. E. A. Parnell on the composition of Inulin. 



drogen 2*44 per cent., with 62*43 per cent, of oxide of lead ; 

 while the other contains carbon 22*46, hydrogen 2*94, with 

 51*23 per cent, of oxide of lead. The following formula? are 

 the nearest which can be given to these numbers: 



24 Carbon 1834*4 



21 Hydrogen . . . 262*0 



21 Oxygen 2100*0 



5 Oxide of lead. . 6972*5 



11168*9 



and 



24 Carbon 1834*4 



18 Hydrogen . . . 224*6 



18 Oxygen 1800*0 



3 Oxide of lead. . 4183*5 



Calculated. 



16*42 



2*35 



18*81 



62*42 



100*00 



Calculated. 



22*81 



2*79 



22*38 



52*02 



Found. 

 16*65 

 2*44 

 18*48 

 62*43 



100*00 



Found. 

 22*46 

 2*94 

 23*37 

 51*23 



8042*5 100*00 100*00 



As first precipitated in the cold, these inulates are hy- 

 drated; they retain this water if dried in the air, give it off 

 slowly by being kept over sulphuric acid, and readily to air at 

 212°. The one which contains 5 PbO gave only 2*00 per cent., 

 the other gave 7*00. This last, with allowance for hygrome- 

 tric moisture, approaches 6*4, which is the calculated number 

 for five equivalents, making the formula C 24 H 18 18 + 3 PbO 

 -f 5 H O. Thus, it would appear, that anhydrous inuiine is 

 C 24 H 18 18 (isomeric with anhydrous cane sugar), which, in 

 the case of inulin dried at common temperatures, is combined 

 with 3 H O. With this water it does not part without decom- 

 position. In the two lead compounds inulin is combined, in 

 one with 3 H O + 5 P b O, and in the other with 3 P b O 

 + 5 H O. It is also possible that inulin in solution may be 

 combined with eight equivalents of water, thus making the 

 series 



C 24 H 18 O i8 + 3HO + 5HO? inulin in solution. 



+ 3 H O inulin dried at common temperature. 



+3PbO + 5HO. 



+3 PbO. 



+3HO + 5PbO. 



That the group of three atoms of water is more strongly 

 attached than the group of five atoms, is proved, first, by dry 

 inulin containing three, and not five atoms of water, in 

 combination with C 24 H 18 18 ; and secondly, by the compound 

 C 24 H 2l 21 + 5 P b O giving off no water without destruc- 



fflk Mag. S. 3. Vol. 17. No, 108. Aug. 1840. K 



