Chemical Science. 



183 



coloured by one volume of chlorine. Hence on dissolving ten 

 grammes of chloride of lime iti water, so as to form one litre 

 of solution, the number of volumes of proof liquor discoloured 

 by one volume of the solution will indicate the number of tenths 

 of a litre of chlorine, which the ten grammes contained ; con- 

 sequently a kilogramme of chloride of lime which has, by such 

 examination given 7°. 6 or 76-hundredths will contain seventy- 

 six litres of chlorine. Each degree, therefore, is equal to 

 ten litres per kilogramme of chloride, and each tenth to one litre. 

 Supposing the sub-chloride of lime perfectly pure, it would contain 

 101.21 litres of chlorine per kilogramme. Generally the niost 

 accurate results are obtained with a weak solution of chlorine, 

 one, for instance, which marks four or five degrees ; if therefore it 

 is found that a solution much surpasses 10° it is well to dilute it 

 with an equal quantity of, or twice as much water, and then double 

 or triple the number of degrees found by the instrument. 



As oxide of manganese varies in quality, it requires to be ex- 

 amined. Pure peroxide is formed of manganese 3.5578 grammes 

 and oxygen two grammes ; it will produce 4.4265 gr., or 1.3963 

 litres of chlorine, at the temperature and pressure before-mentioned ; 

 so that 3.98 gr.wili produce one litre of chlorine, and one kilogramme, 

 21.23 litres of chlorine. In the examination therefore 3.98 gr. of 

 the oxide to be examined are to be treated at a moderate heat 

 with muriatic acid in excess, and the chlorine received into a little 

 less than one litre of milk of lime. Towards the end of the ope- 

 ration the mixture in the retort is to be boiled to expel all the 

 chlorine from the vessel, the milk of lime is to be made up to a 

 litre with water, and this chloride tested as before, will give the 

 value or power of the oxide of manganese. 



The chlorometer consists of a small balance ; a weight of five 

 grammes ; a mortar to pulverize the chloride of lime, which is neces- 

 sary to ensure exactness ; a jar A. containing half a litre up 

 to the circular line 7n., terminated 

 by two arrows ; the surface of 

 the water should be made to coin- 

 cide with this line and not the 

 upper edge ; an agitator B. to 

 mix the solution of the chloride, 

 it is to be passed up and down, 

 through the liquid. A small 

 C. measure of two and a half 

 cubic centimetres, intended to 

 measure the solution of the chlo- < , 

 ride ; it is to be immersed below n (^ 

 and filled by applying the mouth ^ 

 to the top; then placing the finger \l 



on the top it is easy, in the usual ^ 



manner, to allow the escape of 



