104 Cellulose 



sary to note that the gas disappearing in combination is a 

 volume observed under the conditions of the experiment ; it is 

 corrected therefore for temperature, barometric pressure, and 

 the partial pressure of aqueous vapour, and the corrected 

 number reduced to the weight of the chlorine taking part in 

 the reaction. This weight is 16-17 p.ct. of the weight of the 

 fibre-substance. 



The quantity of the latter which may be conveniently taken 

 is 1-2 grms. ; the quantity of gas, measured under ordinary 

 conditions, required for 2 grms. of the lignocellulose is TOO- 

 120 c.c. It is advisable to take a reaction bottle, of capacity 

 equal to twice this volume. 



The errors of experiment in such a determination are not 

 very considerable ; they may be minimised by keeping the 

 reaction bottle submerged in water of constant temperature, 

 and shielding it from the light, to prevent interaction of 

 the chlorine and water ; also by observing the precautions 

 usual in the measurement of gas volumes. 



(2) Determination of HCl formed in the reaction. The 

 quinone chloride formed in the reaction is slightly soluble in 

 water, but almost insoluble in a solution of common salt (20 

 p.ct. NaCl). By washing the chlorinated fibre with a neutral- 

 ised salt solution, the hydrochloric acid may be removed. The 

 reaction bottle being disconnected, the salt solution is poured 

 down the sides, the fibre and bottle being further washed once or 

 twice with the salt solution. Residues of chlorine are removed 

 by passing a current of air for a minute or two through the solu- 

 tion, which is then treated with standard alkali in the usual way. 



The chlorine converted into hydrochloric acid is, in the 

 case of jute, approximately one half the total chlorine entering 

 into reaction, i.e. from 8-8-5 P- ct - The reaction appears, 

 therefore, to be one of simple substitution of hydrogen. In 

 the case of other lignocelluloses, yet to be examined, it is 



