44 WRITINGS OF JAMES SMITHSON. 



made slightly red hot. It then weighed 3.15 grains. It 

 was muriate of soda. 



The solution of this muriate of soda being tried with 

 solutions of carbonate of ammonia and oxalic acid, did not 

 afford 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 4.9 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 addition of sulphate of ammonia to it, it 

 produced crystals of compound sulphate of alumina and 

 ammonia, in regular octahedrons. 



This alum and alumina were again mixed and digested in 

 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 J of sulphate of barytes to be sul- 

 phuric acid, the quantity of the alumina will be 3.1 

 0.4 ~ 2.7 grains. 



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

 since Mr. DAVY'S important discovery of the nature of what was called 

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

 to be salts, but metallic compounds analogous to oxides. 



