1820.] Oxi/muriate of Lime. 403 



the lime is decomposed, giving out its oxygen ; wliile the chlo- 

 rine uniting to the calcium constitutes chloride of calcium. I 

 suppose him aware likewise that an atom of oxygen is equivalent 

 to half a volume, and an atom of chlorine to a whole volume. 

 Hence in the above process, for every volume of chlorine that 

 imites to the calcium, half a volume of oxygen gas is disengaged. 

 We can, therefore, easily determine how much chlorine exists in 

 chloride of calcium, provided we know the quantity of oxygen 

 gas disengaged from the lime during the formation of chloride of 

 calcium ; for the bulk of the chlorine will be just double that of 

 the oxygen gas. 



Now when chloride of lime is exposed to heat, the lime is 

 decomposed, in consequence of the superior affinity of the chlo- 

 rine for calcium at a high temperature. The lime gives out its 

 oxygen, and the chloride of lime is converted into chloride of 

 calcium. This is what happened in the preceding experiment. 

 It is obvious, therefore, that in order to determine the volume of 

 chlorine contained in the 2714 grs. of bleaching powder, we have 

 only to double the volume of oxygen gas disengaged. We have 

 seen that the oxygen amounted to 333-48 cubic inches ; there- 

 fore, the chlorine must have amounted to 66ti"96 cubic inches ; 

 but the specific gravity of chlorine gas is 2"500, and 100 cubic 

 inches of it under the mean temperature and pressure Aveigh 

 76-25 grs. Of consequence, 666-96 cubic inches of chlorine gas 

 are equivalent to 508-557 grs. 



Having thus determined the quantity of water and of chlorine 

 which the bleaching powder contained, it still remained neces- 

 sary to ascertain whether any muriatic acid was present in it. 

 For this purpose I digested the matter which remained in the 

 retort in repeated portions of distilled water till all the muriate of 

 lime (chloride of calcium) in it was dissolved ; but as there was 

 obviously an excess of lime in the bleaching powder, part of 

 which would be dissolved by the water along with the muriate of 

 lime, I caused a current of carbonic acid gas to pass through it 

 till the lime was all si^-parated in the state of carbonate. The 

 liquid was then freed tiom this carbonate by the filter. The 

 liquid which passed through the filter was a solution of muriate 

 of lime in water. It weighed 34,343-75 grs. and its specific 

 gravity was 1-026: 100 grs. of it, being evaporated to dryness, 

 left 3-4 grs. of chloride of calcium dried in the temperature of 

 510°; therefore the quantity contained in the whole hquid 

 amounted to 1167-6875 grs. 



Now when this chloride of calcium is dissolved in water, it is 

 converted into muriate of lime; and 1167-6875 grs. of chloride 

 of calcium is equivalent to 1352-0592 grs. of muriate of lime. 

 Now muriate of lime is a compound of one atom muriatic acid 

 (4-625) + one atom lime (3-625) ; therefore, 1352-0592 grs. of 

 muriate of lime contain 757-973 grs. of muriatic acid, and 

 691-0862 grs. of lime. 



2 c 2 



