NATURAL SCIENCES OF PHILADELPHIA. 93 



i\uently stirred for several days in order that the water should be in frequent 

 contact with the j)articles ; it was then collected on a weighed filter and washed 

 with cold water until the filtrate showed no trace of Sulphuric Acid ; the excess 

 of filtrate was evaporated to dryness, and a thorough analysis made of it, the 

 result of which is the following; : — 



There was in this analysis a loss of Lime or Magnesia, also, of the insoluble 

 residue. 



Selections were made from other specimens which resembled very nearly that 

 above described, it was treated in the same manner as (II.), but the results 

 show a marked difference, there being a smaller percentage of Phosphate of 

 Lime dissolved from (11.) than from (III.) and ajiroportional amount of Chloride 

 of Sodium. To this fact I shall again refer. 



The following is the result of analysis : 



(III.) 



The residue before weighing was carefully dried at 100° C. 

 2.7271 grammes left, residue of 2.3177 gram. 



" " 0.0095 grams. Ag g 



" " 0.3603 " BaO, SO3 



" " 0.2536 " CaO, SO3 



" " 0.0083 " 2MgO, PO5 



" " 0.0600 " 2MgO, PO5 



" " 0.0201 " Na CI 



Chlorine, 0.11 percent. 



Sulphuric Acid, 4.91 " " 



Phosphoric Acid, 1.58 " " 



Lime, 3.84 " " 



Magnesia, 0.11 '• " 



Soda, 0.40 " " 



From another portion of the rock the black portion were selected for analysis, 

 tlie quantity of sulphate of lime is very inconstant. The result of analyses were 

 as follows : 



(IV.) 



0.9170 grammes, .0536 gram. BaO, SO3 gave Sulphuric Acid, 2.01 per ct. , 



" " 0.0510 " CaO, CO2 " Lime, 3.13 '« 



" " 0.1532 " Fe203 " Sesquioxide of Iron, 16.71 " 



" " 0.1123 " AI2O3 " Alumina, 12.25 " 



2.0741 grams, lost by heating, 0.3254 ' 15.69 " 



" " insoluble residue, 0.1314 6.13 " 



Owing to an accident to the platinum crucible just before weighing, the Phos- 

 phoric Acid, was not determined. 

 1857.] 



