512 SEC. 13. CHEMISTRY. 



2456. Apparatus used in the Analysis of Drinking 

 Water. E. Frankland, F.R.S. 



For full particulars, see Journ. of Chem. Soe. for March 1868 

 and June 1876. 



1. Determination of total solid constituents or total solid im- 

 purity. 



Platinum capsule in which half a litre of the water is evaporated to dry- 

 ness, and the residue weighed. 



2. Determination of organic carbon and organic nitrogen. 



A. Apparatus in which one litre of the water is first heated to boiling with 



sulphurous acid, and then evaporated to dryness. 



B. Steel spatula for scraping out the dry residue from the glass capsule. 



C. Cupric oxide for the combustion of the organic matter in the dry 



residue. 



D. Piece of hard glass tube ready to receive the mixture of dry residue, 



cupric oxide, and metallic copper for combustion. 



E. Combustion tube charged and drawn out ready to be placed in furnace. 



F. Sprengel mercurial pump for extracting air from combustion tube before 



the ignition of the mixture of dry residue and cupric oxide, and for 

 extracting the gases from the same tube after ignition. 



G. Hofmann's gas furnace, containing a pair of charged tubes ready for 



combustion. 

 H. Pair of inverted glass tubes for the collection of the gases produced 



by the combustion of the organic matter and ammonia in the solid 



residue. 

 I. Apparatus for the analysis of the gases collected in the tubes H. 



3. Determination of nitrogen in the form of nitrates and nitrites. 

 This is effected by dissolving, in a small quantity of distilled water, the 



solid constituents obtained in determination No. 1, and adding a slight excess 

 of argentic sulphate to convert the chlorides into sulphates. The filtered 

 liquid is then concentrated to a small bulk, mixed with rather more than its 

 own volume of concentrated sulphuric acid, and then introduced over mercury 

 into the tube K, through the cup and stop-cock. The lower end of the tube 

 is now firmly closed by the thumb, and the contents violently agitated by a 

 simultaneous vertical and lateral movement, in such a manner as always to 

 leave an unbroken column of mercury, at least an inch long, between the acid 

 liquid and the thumb. In about a minute from the commencement of the 

 agitation a strong pressure begins to be felt against the thumb of the operator, 

 and mercury spurts out in minute streams as nitric oxide gas is evolved. In 

 from three to five minutes the re-action is completed, and the nitric oxide 

 evolved must then be transferred for measurement to the apparatus No. 2 I. 

 The volume of the nitric oxide so measured is exactly equal to that of the 

 nitrogen as nitrates and nitrites contained in one litre of the water. 



24r56a. Apparatus for Analysis of Gases. Modification 

 of that described by Frankland and Ward. For full description 

 see Journ. of Chem. Soc. 1869, II., vii., 313. 



Professor H. McLeod. 



2456b. McLeod's modification of Frankland's Apparatus 

 for the Analysis of Gases. E. Cctti $ Co. 



