ANALYSIS OF LITHOMARGE. 



perfluous acid being poured off, and the refidu- 

 um throughly wafhed in diftilled water, and af- 

 terwards dried, it weighed 47 pounds; one fourth 

 of which was u fine white iiliccous powder, and 

 the reil, a powder rather courier, and of a co- 

 lour inclining to purple. The colour was poili- 

 b!y obtained from the muriatic acid, and owing 

 lo a portion of iron. 



That the folution, containing argillaceous 

 c;uth, calcined iron, magneiia, and chalk, re- 

 quired an excefs of acid, is evident from the 

 few former experiments. 



But that thcfe fubltances might bci procured 

 fcparate, and their weight afcertained, the fo- 

 lution was divided into two equal parts. The 

 firft was employed for the inveiligation of the 

 chalk and magneiia, the other icterved to exa- 

 mine the argillaceous and ferruginous matter. 



The firfl being made very warm, was gradu- 

 ally faturatcd with aerated chalk, with fuch 

 prcciiion, that neither too much nor too little of 

 the precipitant was ufed; fo that the argillace- 

 ous earth and the iron only being alVecled by it, 

 the whole of the magncfia, which burnt lime, not 

 aerated chalk, precipitates, might remain un- 

 diiturbed. The fcdimtnt was then collected in- 

 to a nitre, and was wafhed with warm water, 

 until all the gypfum was diflolved. The iolu- 

 tion being evaporated to dryncfs, difcovered 

 yjtriolated chalk and mugnclia, which were fe- 



