Dr. Ure on Chloride of Lime. 27 



ric acid, sp. gr. 1.846 (or rather its equivalent of dilute acid, 

 1.65), and 14 of manganese. Others employ a great deal less 

 manganese; about 70 or 80 to 100 of salt. It is easy, however, 

 to get good approximate proportions for practice. My expe- 

 riments on the quantity of chlorine, producible from a certain 

 weight of good English manganese, gave 59 grains of the 

 former for 100 of the latter. But 59 parts of chlorine are 

 equivalent to 98-i- of common salt; hence in round numbers 

 100 parts of such manganese would have required 100 parts of 

 common salt. Therefore the true proportions become 100 of com- 

 mon salt, 100 of manganese ; 8 If oil of vitriol for saturating the 

 soda in the common salt, and 95f oil of vitriol for saturating 

 the 86 of metallic oxide in 100 of manganese ore; constituting 

 of the liquid acid 177.4 parts, to 100 of each of the other arti- 

 cles. As oxide of iron, so often mixed with manganese, has 

 nearly the same prime equivalent, we reckon its saturating 

 power the same in the above calculation. To add a quantity 

 of salt beyond what is equivalent to the manganese and oil of 

 vitriol is impolitic ; it occupies the alembic unnecessarily, and 

 obstructs the mutual action of the muriatic acid and manganese. 

 And, if the oil of vitriol be not adequate to separate from the 

 salt, as much muriatic acid as the manganese present can 

 change into chlorine, the process is injudicious and wasteful. 

 The approximate value of manganese for this manufacture may 

 be readily ascertained by the recurved glass tube, described 

 above, for the analysis of bleaching powder. The film soon 

 formed of dense muriate of manganese, protects the mercury. 

 Or the chlorine disengaged from 100 grains of manganese 

 covered with muriatic acid in a matrass, may be conducted by 

 a glass tube into a dilute solution of a known sulphate of 

 indigo. 



From the preceding computation, it is evident that 1 ton 

 of salt with 1 ton of the above native oxide of manganese pro- 

 perly treated, would yield 0.59 of a ton of chlorine, which 

 would impregnate 1.41 tons of slaked lime, producing 2 tons 

 of bleaching powder, stronger than the average of the com- 

 mercial specimens; or allowing for a little loss, which is 



