246 Chloride of Aluminium and its Analysis. 



The crucible and alumina, when cool, (the cover having been 

 retained in its place to prevent the access of damp air,) weighed 

 16.4755 grammes. 



The crucible weighed 16.1780 grammes. 



The alumina, is equal to the difference of these weights, =0.2975 

 grammes. 



On removing the alumina from the crucible, it was observed to be 

 very slightly stained gray, where it had been in contact with the 

 platinum. This was caused by the formation of a little muriate of 

 platinum, which was decomposed during the subsequent ignition. 

 This source of error might have been avoided, by decomposing the 

 nitric acid by means of a greater excess of muriatic acid. The error 

 was probably so slight that it would have made no sensible difference 

 in the result, and its tendency is to counteract the shght source of 

 error before noticed, (a visible trace of the nitrate and muriate of 

 alumina not being added to that in the crucible.) 



As a check upon the weight obtained above for alumina, it was 

 weighed, ten minutes afterwards, separate from the crucible, but in 

 the mean time it had been exposed to the air of the room. The 

 room had had a fire made in it but a short time, so that the air was 

 rather damp. The alumina then weighed 0.306 grammes, and 

 twenty minutes after it weighed 0.312 grammes. 



The chlorine in 0.646 grammes of the chloride of aluminium has 

 been found to be 0.5068118. The aluminium is then equal, by dif- 

 ference, to 0.646 cl. al.-0.5068118cl. = 0.1391882 grammes. 



From what precedes, the chloride of aluminium obtained by 

 Wohler's process is composed of 



Chlorine, - . - 0.5068118 or 78.4538 

 Aluminium, - - - 0.1391882 " 21.5462 



0.6460000 100.0000 



Admitting the weights obtained in the preceding analysis as accu- 

 rate, the following numbers are chemical equivalents. 



Second, some hydrate of alumina was dissolved in muriatic acid, and when 

 the solution was evaporating-, nitric acid was added. The solution was evapora- 

 ted to dryness, put in a tube hermetically closed at one end, then drawn down to a 

 narrow neck, communicating with the wider part of the tube, to serve as a re- 

 ceiver, and the tube beyond drawn down to a long narrow neck. The heat was 

 raised very gradually, as in the experiment of heating the muriate in the platinum 

 crucible, but muriatic acid and some fumes of nitrous acid only were evolved. 



