20 On the New Jersey Marls, 



with phosphate of soda and ammonia, which produced a 

 precipitate of ammoniacal phosphate of magnesia. This 

 precipitate, on exposure to a strong heat, yielded 0.15 

 grammes of phosphate of magnesia, equivalent to 0.055 

 grammes of magnesia on 3 grammes, or 1.833 per 100. 



E. In recapitulating the above results, the great loss 

 induced me to believe, that this mineral contained a con- 

 siderable proportion of alkali ; in order to ascertain this, 

 3 grammes, in the state of a fine powder, were boiled 

 with muriatic acid ; and, after the entire decomposition 

 was effected, the mixture was evaporated to dryness, the 

 residue was treated with water, and the solution filtered 

 to separate the silica. It was then treated with an excess 

 of subcarbonate of ammonia, and again filtered to sepa- 

 rate the precipitate. The filtered liquor was proved by ox- 

 alate of ammonia to be free from lime : it w?=s evaporated 

 to dryness, and the saline mass was exposed to a mode- 

 rate red heat. After the volatilisation of the ammoniacal 

 salts, the fixed residue entered into fusion, and it weighed 

 0.55 grammes : it was boiled with water, and the solu- 

 tion was filtered to separate the magnesia resulting from 

 the decomposition of the muriate: it weighed 0.07 gram- 

 mes. The liquor was then evaporated slowly, and small 

 regular, and well defined cubic crystals were thus obtain- 

 ed, which, after being dried and exposed to the air, did 

 not deliquesce. They were dissolved in water, and the 

 concentrated solution treated with muriate of platina, gave 

 a yellow precipitate of muriate of potash and platina, 

 which, owing to its abundance, induced me to believe 

 that the alkali in question was entirely potash. On de- 

 ducting the 0.07 grammes of magnesia from the 0.55 

 grammes of muriate of potash and magnesia, we have 

 0.48 grammes of muriate of potash, equivalent to 0.3036 

 grammes of potash on 3 grammes, or 10.12 per lOOo 



