PHYSICAL AND LITERARY, i^ 



^d $' grains of unlolublc matter, which 

 acquired little cohefion by drying, and 

 confided in a great meafurc of a very 

 jfine fand. 



These are tte jnoft remark.ible dif- 

 ferences that have hitherto occurred to' 

 me in examining the reftdua of different 

 jnarles. I thought it neceffary to give a 

 .detail of them, both becaufe the compo- 

 fition of the unloluble part of our fub- 

 jenSl: is thereby dem.onftrated, and becaufe 

 the preceeding experiments w^ill after- 

 w^ardb ferve to explain a difficulty which 

 tvould not otherwife admit of an eafy 

 folution. 



SECTION IV. 



WE muft now return to the pellu-* 

 cid liquor which pafTed thro' the filter 

 in Expe'imeat 3. As this liquor con- 

 tains, ID an invilible ftate, the lubllance 

 which, in combination with the part 

 examined in Se(fl:ion 3 compofed the o- 

 riginal raarle j if we can difcover the 



nature 



