AQ6 Determination of Cellulose in Drinking- Water. 



to use a considerable excess ; and finally lie titrates back 

 with the standard permanganate, and thus becomes provided 

 with numerical data expressing how much oxygen has been 

 used up by the litre of water. 



We have just directed that 1 litre of water should be taken 

 for an operation ; and that quantity will be found convenient ; 

 but, as will strike the chemical reader who reflects on the con- 

 ditions which limit the accuracy of analytical processes, there 

 is nothing to forbid resort to a much larger scale if the highest 

 degree of delicacy and accuracy were desired. In such a case 

 ten litres successively introduced into the same retort would be 

 advantageous. 



We have worked on 4 litres successively introduced. 



On applying the process, we have obtained the following 

 results :— 



Oxj'gen consumed 

 per litre of water, 



Excellent distilled water 0*13 milligrm. 



Thames water by a Water Company . 2*30 „ 



which show a striking difference between common drinking- 

 water and water of the purest description. 



Experiments on dilute solutions of cane-sugar have given 

 results approximating very well to theory. Cane-sugar, in- 

 deed, we have subjected to a course of oxidations ranging over 

 a very varied scale — from 5 milligrms. to upwards of 10 grms., 

 at a single operation. The reaction is precise, viz. : — 



(1) C 12 H 22 O 11 + O 20 =ll(H 2 O) + 4(CO 2 ) + 4(C 2 O 3 ): 



(2) C 12 H 22 O n + 24 =11 (H 2 0) + 12(C0 2 ). 



Equation (1) is valid if the action be restricted to the alka- 

 line solution ; and equation (2) is valid when the oxidation has 

 been carried forward so as to be finished in the acid liquid. 

 We postpone the publication of the experiments, and content 

 ourselves with the general statement that we can by means of 

 solution of permanganate effect perfect combustions of a num- 

 ber of organic compounds, the combustions taking place 

 whilst the organic matter remains in aqueous solution. 



Westminster. May 1878. 



