III. ANALYSIS. 623 



2456r. Apparatus for compression of Liquids by 

 Regnault's Piezometer. 



Golaz, 24 Rue des Fosses, St. Jacques, Paris. 



This apparatus, constructed by the exhibitor for M. Regnault, consists of a 

 thick copper cylinder closed at its upper part by a copper plate .bolted to the 

 circumference and provided with three tubes. To the central tube is cemented 

 the glass stem of the piezometer. The right hand tube has a stop-cock which 

 opens into the atmosphere and serves for relieving the pressure ; the left- 

 hand tube has also a stop- cock which is attached by a leaden tube to a block 

 fitted with two other stop -cocks at right angles to it, and which is cemented 

 at the other end to the stem of the piezometer ; the other branch is connected 

 with a compression pump or a pressure reservoir. The cylinder is first filled 

 with water by means of the two upper stop-cocks, and pressure can then be 

 applied under all the conditions indicated by M. Regnault. " Mem. de PAcad." 

 t. 21. 



III. APPARATUS USED IN ANALYSIS. 



2456. Apparatus used in the Analysis of Drinking 

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



For full particulars, see Journ. of Chem, Soc. 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. 

 JP\ 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. Hofmanu'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 



