184 Dr. Thomson on Oxymuriate of Lime. [Marcn, 
7. From the preceding experiments, it follows (supposing 
what is called oxymuriate of lime to be a chloride of lime), that 
the composition of the bleaching powder which I examined was 
as follows : 
1. Undissolved portion ; viz. lime....... CLG Bs 0: 
2. Dissolved portion: 1. Chlorine. .......... 13°56 
2. Combined lime. .... 10°92 
3. Uncombined lime . 2°31 
38°47 
Hence the water and the impurities in 50 gr. of the bleaching 
powder, which I examined, amounted to 11-53 gr. or somewhat 
more than th of the total weight. ; 
§. The uncombined lime in the specimen which I examined, 
which was newly prepared, amounted to 15°87 gr.; while the 
orion united to the chlorine was 10°92 gr.; so that the uncom- 
ae lime was to the combined nearly in the proportion of three 
to two. In the experiments which Mr. Dalton published on this 
salt, in the first number of the Annals of Philosophy, he found 
one half the lime united to the chlorine. I made some attempts 
to repeat his mode of analysis, but did not succeed. When 
protosulphate of iron was added to the solution of the bleaching 
salt, it acquired a deep red colour from a few drops, and it 
speedily became impossible for me to determine whether I had 
added a sufficient quantity of protosulphate or not. Mr. Dalton 
has not been explicit enough in his description of his mode of 
analysis, to enable other chemists to repeat his process. Of 
course I am unable to state, whether the difference between Mr. 
Dalton’s results and mine be owing to the different modes of 
analysis which we followed, or to a difference in the composition 
of the bleaching powders which we examined. I think it very 
likely that both causes contributed to produce the difference 
which exists between us. 
It. Nature of Oxymuriate of Lime. 
But the principal object of my experiments on the bleaching 
powder was to ascertain the nature of the compound formed 
. when chlorine is made to pass through hydrate of lime. 
1, 1160 gr. of the dry powder were put into a glass retort, the 
beak of which was luted to a bent tube, the end of which was 
plunged into a water trough, and a glass jar full of water was 
inverted above it. . The retort being heated on a sand bath, gas 
came over, and continued to come over for some hours. The 
whole quantity thus extricated measured 164 cubic inches, and 
was pure oxygen gas. The dry salt in the retort had lost its 
smell and its action on vegetable colours; and when digested 
in water, a solution of common muriate of lime was obtained. I 
conclude from this experiment that, in the bleaching salt, the 
