071 the New Jersey Marls. 19 



0.294 grammes on 3 grammes, or 9.80 per 100. To 

 prove that the loss by calcination was occasioned by 

 moisture, a portion of the mineral was calcined in a glass 

 retort, and drops of water were thus obtained. 



B. The residue of the preceding calcination (A.) was 

 boiled with concentrated muriatic acid, the solution was 

 of a reddish yellow colour, and the insoluble portion be- 

 came gelatinous ; the mixture was evaporated to dry- 

 ness ; it was then treated with water acidulated with mu- 

 riatic acid, and again moderately evaporated, more water 

 was then added, and the solution was filtered : the silica 

 remaining on the filter, after edulcoration and calcination, 

 weighed 1.495 grammes on 3 grammes, or 49.833 per 

 100. 



C. After the separation of the silica, the liquor (B.) was 

 treated with an excess of subcarbonate of ammonia, which 

 produced a precipitate of a reddish brown colour ; this 

 precipitate, after being perfectly washed and strongly cal- 

 cined, weighed 0.90 grammes ; it was repeatedly calcin- 

 ed with caustic potash, until the alumina was completely 

 separated ; the alcaline liquor, being of a light yellow co- 

 lour, indicated the presence of a trace of protoxide of 

 chrome. After the entire separation of the alumina, the 

 peroxide of iron weighed 0.72 grammes, but as the mi- 

 neral is of a green colour, the iron must be estimated as a 

 protoxide, and the 0.72 grammes of peroxide are equiva- 

 lent to 0.646 grammes of protoxide on 3 grammes, or 

 21.533 per 100. — The peroxide of iron was mixed with 

 a trace of lime ; when calcined with caustic potash, it 

 gave no cameleon, and, therefore, contained no manga- 

 nese. On estimating the alumina by difference we have 

 0.18 grammes on 3 grammes, or 6.0 per 100. 



D. The liquor (C.) when treated with oxalate of potash, 

 was found to have retained no lime ; it was then treated 



