32 On the Composition of Zeolite, 



lutions of carbonate of ammonia and oxalic acid, did not 

 aflTord the least precipitate, which would have happened had 

 the zeolite contained any lime, as the muriate of lime* 

 would not have been decomposed by the ignition. 



The remaining matter, from which this muriate of soda 

 had been extracted, was repeatedly digested with marine 

 acid, till all that was soluble was dissolved. What remained 

 was silica, and, after being made red hot, weighed 4-^ 

 grains. 



The muriatic solution, which had been decanted off from 

 the silica, was exhaled to a dry state, and the matter left 

 made red hot. It was alumina. 



To discover whether any magnesia was contained amongst 

 this alumina, it was dissolved in sulphuric acid, the solution 

 evaporated to a dry state, and ignited. Water did extract 

 some saline matter from this ignited alumina, but it had not 

 at all the appearance of sulphate of magnesia, and proved 

 to be some sulphate of alumina which had escaped decom- 

 position ; for on an additi(m of sulphate of ammonia to it, 

 it produced crystals of compound sulphate of alumina and 

 ammonia, in regular octahedrons. 



This alum and alumina were ao;ain mixed and digested 

 m ammonia, and the whole dried and made red hot. The 

 alumina left, weighed 3*1 grains. 



Being suspected to contain still some sulphuric acid, this 

 alumina was dissolved in nitric acid, and an excess of ace- 

 tate of barytes added. A precipitate of sulphate of barytes 

 fell, which, after being edulcorated and made red hot, 

 weighed ,1-2 grains. If we admit one-third of sulphate of 

 barytes to be sulphuric acid, the quantity of the alumina 

 will be = 31 — 4 = 2-7 griins. 



From the experiments of Dr. Marcet f, it appears that 

 3-15 grains of muriate of soda afford \•^ grains of soda. 



fience, according to the foregoing experiments, the ten 

 grains of zeolite analysed, consisted of 



Silica 4't)0 



AluiTiina 2*70 



Soda 1-70 



Ice 0-93 



10'25 



* These names are retained for the present, as being familiar, though, 

 since Mr. Davy's important discovery of the nature of what was called oxy- 

 muriatic acid, the substances to which they are applied are known not to 

 be salts, but metallic compound- analogous to oxides. 



\ Philosophical Tr^nsjctiona, 1807. 



As 



