106 PROCEEDINGS OF THE ACADEMY OF [1894. 



of the material, as revealed under the microscope, are atoms. It 

 possesses no dichroism. Specific gravity 2.566. 



When heated in a Buusen flame it slightly decrepitates and emits 

 the yellow light due to sodium. When heated in a test tube it 

 gradually becomes dark gray, indicating some carbonaceous matter 

 and, when heated strongly, an oily matter and water having an acid 

 reaction are emitted. Heated with the blowpipe on charcoal with 

 carbonate of soda it effervesces and finally produces a white enamel. 

 Heated by itself, on the charcoal, it produces an intense white incan- 

 descence and, reheated with cobalt solution, a fine blue is obtained. 



It is not soluble in Avater, sulphuric, hydrochloric or nitric acids, 

 but if boiled with a caustic alkali it dissolves. If, however, the 

 substance is brought to a red heat and there maintained for some 

 time, it is then dissolved by any of the above named acids. 



The chemical analysis, made in duplicate, resulted as follows: 



Alumina (AL.Oa) 33.40 per cent. 



Sulphate alumina (AL^O^SO;;) 7.18 " 



Sulphate potassium (K2 SO4 ) 17.00 " 

 Sulphate sodium (NA., SO, ) 4.91 " 



Water (H, 6) 31.57 " 



Carbonaceous matter, difference 5. 94. 



The carbonaceous matter was not especially determined in the be- 

 lief that in all probability it is an accidental admixture foreign to the 

 composition of the original substance. 



From the analysis above given it is evident that the compound is 

 a highly basic sulphate, and, eliminating the percentage of carbona- 

 ceous matter and finding the oxygen ratios between the sulphur triox- 

 ide, the alumina and all the monoxides, the composition determined 

 is as follows: 



Alumina (AL. O;; ) 39.79 per cent. 18.68 per cent. Oxygen. 



Potassium oxide (Ko O) 7.37 " " 1.25 " " 



Sodium oxide (NA.. O) 1.72 " " 0.44 " " 

 Water (H, 6) 33.56 " " 29.82 " " 



Sulphur trioxide (SO.) 17.55 " " 10.52 " " 



The ratios of the SO3 , ALo O3 , R^ are nearly as : 

 1, 2,' 8 



which may be represented by the formula: 



(ALo O, ) ., - SO, - (Ro 0)3 . 



Here R2 represents Ko , NA2 , H^ . 



There are a number of basic sulphates recorded, all of which seem 



