Mr. E. A. Parnell on the composition of Inulin. 1 29 



clrogen 2-44 per cent., with 62-43 per cent, of oxide oflead ; 

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

 51-23 per cent, of oxide oflead. The following formulae are 

 the nearest which can be given to these numbers : 



Calculated. Found. 



24 Carbon 1834-4 16'42 16-65 



21 Hydrogen . . . 262-0 2'35 2-44 



21 Oxygen 2100*0 18-81 18'48 



5 Oxide of lead. 6972-5 62-42 62-43 



and 



11168-9 



24 Carbon 1834-4 



18 Hydrogen . . . 224'6 



18 Oxygen 1800-0 



3 Oxide oflead. 4183-5 



8042-5 



100-00 



Calculated. 



22-81 



2-79 



22-38 



52-02 



100-00 



100-00 



Found. 

 22-46 

 2-94 

 23-37 

 51-23 



100-00 



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

 d rated; 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 O 18 + 3 PbO 

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

 C 24 H 1S O, 8 (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 



seres 



C H O 



24 



18 18 



+ 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 f>f 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 O 18 ; and secondly, by the compound 



. m 



^"t T T S~* *"* 1818' */ w ^ 1 



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



Phil. Mag. S, 3, Vol. 17. No, 108. dug. 1840. K 



