510 Observations on Chloric Acid and the Chlorates, 



refracting crust. This is^ in itself, a very natural supposition, 

 seeing that the fluid may have discharged its gaseous portion, 

 and left behind it the matters which it held in solution. The 

 cavities however, of this kind, which I have described in a 

 former paper, have no depolarizing action ; and I find that 

 those now under consideration have regular axes of double 

 refraction. Hence the matter which covers them must be a 

 regular crystalline shell, with optical and crystallographic 

 axes — a phaenomenon which has no parallel in mineralogy. 



St. Leonard's College, St. Andrew's, 

 February 15, 1845. 



LXXIV. Observations on Chloric Acid and the Chlorates. 

 By Lewis Thompson. 



To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, 

 A N easy and oeconomical mode of preparing chloric acid 

 -^^*- and some of the chlorates has not been described in any 

 chemical work that I am aware of: the following will be fonnd 

 to answer extremely well. 



Dissolve in two separate portions of boiling water one atom 

 (122-81) of chlorate of potash, and one atom (168-34) of bi- 

 tartrate of ammonia; mix the two solutions together, and set 

 the whole aside in order that the bitartrate of potash may 

 crystallize; then mix the clear solution with an equal bulk of 

 alcohol, and filter or pour off the alcoholic solution of chlorate 

 of ammonia, which must now be boiled in a flask or other 

 narrow-necked vessel, with an excess of recently-precipitated 

 carbonate of baryta, until the ammonia is expelled, water being 

 occasionally added ; then filter the fluid, evaporate, and cry- 

 stallize. In dissolving the chlorate of potash and bitartrate of 

 ammonia, as little water must be used as possible. 



The chlorates of strontla and lime may be prepared in a 

 similar manner; and the metallic chlorates are easily prepared 

 by decomposing the chlorate of baryta by means of asulphatef 

 of the base required. 



Chloric acid is best obtained by dissolving a given weight 

 of chlorate of baryta, and adding no more sulphuric acid than 

 is sufficient to combine with the base ; several hours or eveif 

 days, however, appear necessary to effect this decomposition 

 in the cold ; after which the whole may be filtered and care- 

 fully evaporated at a low heat. When sulphuric acid is added 

 to a solution of the chlorate of baryta, as long as it gives ^ 

 precipitate, I have always found an excess of it in the chloric 

 acid. 



