2'22 Mk Gay-Lassac on the Chloride of Lime. [Sept. 



Part II. 



Description of the Chlorometer, and of the Method of proceeding 

 in the Assay of the Chloride of Lime. 



A. (Plate XXXI.) Small balance. 



B. Weight of 5 grammes. 



C. Mortar to pulverize the chloride of lime ; by this opera- 

 tion we ensure greater accuracy in the assay, as the chloride 

 often contains lumps which dissolve slowly. 



D. Jar, with a foot, containing exactly half a litre when filled 

 to the circular line m, terminated by two opposite arrows ; the 

 surface of the water must coincide with this line, and not its 

 upper edge, which is indicated in the figure by the dotted line. 



The jar must be placed on a horizontal table. 



E. Stirrer, to stir the solution of the chloride and make it 

 homogeneous : it is to be plunged down into the liquor, and 

 raised up again, alternately, without being taken out of it. 



F. Small measure, or tube, of 2l T cubic centimetres, which is 

 unvarying for the chlorometer in question ; it is intended to 

 measure the solution of chloride of lime. To fill this tube, it 

 is plunged into the chloride to just above the circular line n, 

 which terminates its capacity, and the chloride made to rise in 

 it by suction ; when filled, the fore finger, which should neither 

 be too dry nor too wet, is placed on the upper orifice, the tube 

 raised out of the liquid, and its lower extremity supported 

 against the margin of the jar, as seen at G, or against the finger. 

 By a little management of the pressure, and a slight alternate 

 circular motion of the stem between the fingers, the liquid de- 

 scends slowly, and when the lower part of the concave curve 

 which terminates it is in the plane of the little circular line, 

 the stream is immediately stopped, by increasing the pressure 

 and the tube emptied into the drinking glass H.* 



H. Large drinking glaes for mixing the indigo proof tincture 

 with the chloride. It should be placed on a sheet of white 

 paper, in order more easily to observe the changes of colour 

 which the indigo undergoes by the action of the chlorine. 



I. Tube for measuring the proof tincture: each great divi- 

 sion, or degree, is equal to the capacity of the small tube F, 

 and is divided into 5 parts, which is sufficient for practice ; 

 but for calculation, the fifths are reduced to tenths. This tube 

 is filled with the proof tincture up to the degree 0, which is 

 easily accomplished, by putting into it rather more tincture 

 than is necessary, and pouring oft' the excess, drop by drop, by 

 the beak, the extremity of which should be covered by a slight 

 layer of wax or tallow, to assist the running off' in drops. 



* When the tube becomes opaque, it is cleared by dipping it in muriatic acid, or 

 vinegar. 



