14 
N. C. AGRICULTURAL EXPERIMENT STATION. 
Alumina .—The combined weight of ferric oxide and alumina, 
minus the ferric oxide obtained, gives the weight of alumina. 
Chlorine .—Weigh 5 grams of ash into a beaker, add 100 c. c. of water 
and a little nitric acid, let stand lor one hour, filter, wash, neutralize 
the filtrate with sodium carbonate, and determine the chlorine with 
a standard solution of silver nitrate, with the aid of yellow chro¬ 
mate of potash. 
Carbonic acid .—One gram of the ash is weighed into a Shepard 
alkalimeter, a little water added, and the carbonic acid freed with 
dilute nitric acid, with the aid of a gentle heat, the loss being the 
carbon dioxide. This method, if properly manipulated, is highly 
satisfactory. 
Insoluble silica , or sand .—Weigh 1 gram into a beaker, add a small 
quantity of water and hydrochloric acid in excess, heat for some 
time on a water-bath, filter through a tared iGooch crucible, ignite, 
and weigh as Si 02 or sand. 
Soluble silica .—The total silica obtained by bringing the solution 
to dryness before filtering, minus the insoluble silica, gives the 
soluble silica. 
