252 ANALYSIS OF NITRE. 



of lime would have contained 1.111 grms. of chlorine, 

 or 22.22 per cent. 



Perfectly pure chloride of lime (Ca C1 + CaO, CIO), 

 which is never met with in commerce, contains 48.9 

 per cent, of available chlorine. 



II. A weighed quantity of chloride of lime is mixed 

 with water, in a flask, an excess of protochloride of 

 iron, free from sesquichloride, added, and afterwards 

 some hydrochloric acid. Several bright weighed strips 

 of copper are then introduced, and the solution boiled 

 until the protochloride at first formed is converted into 

 subchloride; the copper is then withdrawn, washed, 

 dried, and weighed. The calculation is effected as in 

 No. 121. 



124. ANALYSIS OF NITRE. 



In order to determine the amount of moisture in 

 crude nitre, from 5 to 10 grms. of the specimen, pre- 

 viously reduced to powder and dried by exposure to 

 air, are heated to about 150. 



The determination of the quantities of the foreign 

 salts present in the specimen, such as sulphates and 

 chlorides, lime and magnesia, by the ordinary methods, 

 would occupy too much time ; it would be preferable 

 to estimate them by means of standard solutions of the 

 reagents, i. e., by measuring the quantities of the latter 

 required to effect complete precipitation. 



The appearance of the fracture is regarded as an 

 indication of the quality of the nitre ; in pure nitre, 

 the fracture is lustrous, and exhibits a well-defined 

 crystalline appearance; but if not more than 2 per 

 cent, of common salt be present, it is granular and 

 dull. An admixture of nitrate of soda (Chili salt- 

 petre) has the same effect. 



Another method, which is likewise, however, inac- 



